Eloxx Pharmaceuticals (ELOX) 10-K 16 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	ELOX
Entity Registrant Name	ELOXX PHARMACEUTICALS, INC.
Entity Central Index Key	1,035,354
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding	27,527,738
Entity Public Float		$ 7,092,700

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 24,049	$ 2,212
Restricted bank deposit	102	38
Prepaids and other current assets	355	837
Total current assets	24,506	3,087
Property and equipment, net	278	41
Total assets	24,784	3,128
Current liabilities
Accounts payables	1,530	1,899
Accrued expenses	1,893	619
Total current liabilities	3,423	2,518
Commitments and contingencies (Note 9)
Stockholders' equity:
Series A, B-1, B-2 and C Preferred Stock, $0.01 par value 5,000,000 and 19,965,708 shares authorized as of December 31, 2017 and 2016, respectively; 0 and 7,638,263 shares issued and outstanding as of December 31, 2017 and 2016, respectively		76
Common stock, $0.01 par value 500,000,000 and 29,948,562 shares authorized as of December 31, 2017 and 2016, respectively; 27,527,738 and 4,205,278 shares issued and outstanding as of December 31, 2017 and 2016, respectively	274	42
Additional paid-incapital	60,047	18,238
Accumulated deficit	(38,960)	(17,746)
Total stockholders' equity	21,361	610
Total liabilities and stockholders' equity	$ 24,784	$ 3,128

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred Stock, par value	$ 0.01	$ 0.01
Preferred Stock, shares authorized	5,000,000	19,965,708
Preferred Stock, shares issued	0	7,638,263
Preferred Stock, shares outstanding	0	7,638,263
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	29,948,562
Common stock, shares issued	27,527,738	4,205,278
Common stock, shares outstanding	27,527,738	4,205,278

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating expenses:
Research and development, net	$ 16,398	$ 8,986	$ 5,842
General and administrative expenses	3,992	854	442
Total operating expenses	20,390	9,840	6,284
Loss from operations	(20,390)	(9,840)	(6,284)
Financial and other expenses, net	824	7	122
Net loss	$ 21,214	$ 9,847	$ 6,406
Basic and diluted net loss per share	$ 4.75	$ 2.60	$ 1.67
Weighted average number of Common Stock used in computing basic and diluted loss per share	4,976,377	4,205,277	4,148,389

Statements of Changes in Stockh

Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Series A Preferred Stock [Member]	Series B 1 Preferred Stock One [Member]	Series B 1 Preferred Stock [Member]	Series C Preferred Stock [Member]	Preferred Stock	Preferred StockSeries A Preferred Stock [Member]	Preferred StockSeries B 1 Preferred Stock One [Member]	Preferred StockSeries B 1 Preferred Stock [Member]	Preferred StockSeries C Preferred Stock [Member]	Common Stock	Additional paid-in capital	Additional paid-in capitalSeries A Preferred Stock [Member]	Additional paid-in capitalSeries B 1 Preferred Stock One [Member]	Additional paid-in capitalSeries B 1 Preferred Stock [Member]	Additional paid-in capitalSeries C Preferred Stock [Member]	Accumulated deficit
Balance at Dec. 31, 2014	$ 2,775					$ 20					$ 41	$ 4,207					$ (1,493)
Issuance of preferred stock and warrants to purchase preferred stock and common stock			$ 3,022					$ 10						$ 3,012
Balance, shares at Dec. 31, 2014						2,022,493					4,105,449
Issuance of preferred stock and warrants to purchase preferred stock and common stock, shares								1,002,049
Exercise of options into Common Stock											$ 1	(1)
Exercise of options into Common Stock, shares											99,829
Receipt on account of shares	300											300
Stock-based compensation	92											92
Issuance of stock		$ 860					$ 11						$ 849
Issuance of stock, shares							1,073,157
Net loss	(6,406)																(6,406)
Balance at Dec. 31, 2015	643					$ 41					$ 42	8,459					(7,899)
Balance, shares at Dec. 31, 2015						4,097,699					4,205,278
Issuance of preferred stock and warrants to purchase preferred stock and common stock			$ 3,650	$ 5,736				$ 12	$ 19					$ 3,638	$ 5,717
Issuance of preferred stock and warrants to purchase preferred stock and common stock, shares								1,174,138	1,929,676
Exercise of warrants into Series A preferred stock	350					$ 4						346
Exercise of warrants into Series A Preferred Shares, shares						436,750
Stock-based compensation	78											78
Net loss	(9,847)																(9,847)
Balance at Dec. 31, 2016	$ 610					$ 76					$ 42	18,238					(17,746)
Balance, shares at Dec. 31, 2016	4,205,278					7,638,263					4,205,278
Conversion of convertible loan into Series C preferred stock	$ 3,168					$ 8						3,160
Conversion of convertible loan into Series C preferred stock, shares						825,213
Exercise of options into Common Stock	17											17
Exercise of options into Common Stock, shares											16,699
Stock-based compensation	101											101
Issuance of stock	17,006				$ 18,427					$ 63	$ 63	16,943				$ 18,364
Issuance of stock, shares										6,311,076	6,333,333
Conversion of Series A, B-1, B-2 and C preferred stock into common stock with respect to the Reverse Merger						$ (147)					$ 147
Conversion of Series A, B-1, B-2 and C preferred stock into common stock with respect to the Reverse Merger, shares						(14,774,552)					14,774,552
Shares issued with respect to the Reverse Merger	(170)										$ 22	(192)
Shares issued with respect to the Reverse Merger, shares											2,197,876
Provision related to the Technion exit fee	3,416											3,416
Net loss	(21,214)																(21,214)
Balance at Dec. 31, 2017	$ 21,361										$ 274	$ 60,047					$ (38,960)
Balance, shares at Dec. 31, 2017	27,527,738										27,527,738

Statements of Changes in Stock6

Statements of Changes in Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Issuance expenses	$ 494
Series B 1 Preferred Stock One [Member]
Issuance expenses			$ 93
Series B 1 Preferred Stock [Member]
Issuance expenses		$ 264
Series C Preferred Stock [Member]
Issuance expenses	$ 573

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (21,214)	$ (9,847)	$ (6,406)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation and restricted shares	101	78	92
Depreciation	39	8	5
Amortization and revaluation of discount in respect to convertible loan	668
Provision related to the Technion exit fee	3,416
Change in operating assets and liabilities:
Prepaid expenses and other current assets	709	(482)	(276)
Accounts payable	(583)	1,250	529
Accrued expenses	929	149	321
Net cash used in operating activities	(15,935)	(8,844)	(5,735)
Cash flows from investing activities:
Investment in restricted bank deposit	(64)	(14)
Maturity of (investment in) restricted bank deposit			1,496
Purchase of property and equipment	(237)	(36)	(10)
Cash received upon the Reverse Merger	123
Net cash (used in) provided by investing activities	(178)	(50)	1,486
Cash flows from finance activities:
Proceeds from exercise of warrants into Series A preferred stock		350
Proceeds from exercise of options into common stock	17
Proceeds from issuance of Series B-1 preferred stock and warrants to purchase Series B-1preferred stock, net of issuance costs		9,386	3,022
Proceeds from issuance of common stock	17,006
Proceeds from convertible loan and related financial derivative into Series C preferred stock	2,500
Net cash provided by financing activities	37,950	9,736	3,882
Increase (decrease) in cash and cash equivalents	21,837	842	(367)
Cash and cash equivalents at the beginning of the year	2,212	1,370	1,737
Cash and cash equivalents at the end of the year	24,049	$ 2,212	1,370
Supplemental disclosure of non-cash financing activities:
Conversion of convertible loan into Series C preferred stock	3,168
Series A Preferred Stock [Member]
Cash flows from finance activities:
Proceeds from issuance of preferred stock			$ 860
Series C Preferred Stock [Member]
Cash flows from finance activities:
Proceeds from issuance of preferred stock	$ 18,427

Nature of the Business

Nature of the Business	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business	1. Nature of the Business We are a global biopharmaceutical company focused on discovering and developing novel therapeutics for the treatment of rare and ultra-rare premature stop codon diseases. We are harnessing the science of genetic read-through to develop novel drug product candidates that interact with the ribosome to overcome these premature stop codons. Our revolutionary small molecule approach is designed to unleash the potential to restore production of full length functional proteins with the goal of enabling a return toward normal cellular function. We believe there is a broad application of this approach to the over 1800 rare and ultra-rare diseases where nonsense mutation has been implicated in the cause or pathway of human disease. Our research and development strategy is to target rare or ultra-rare diseases where a high unmet medical need, nonsense mutation bearing, patient population has been identified. We focus on clinical indications where there is a high unmet medical need, established preclinical read-through or personalized medicine experiments that are predictive of clinical activity, and a definable path for Orphan Drug development, regulatory approval, patient access and commercialization. We believe patient advocacy to be an important element of patient focused drug development and seek opportunities to collaborate with patient advocacy groups throughout the discovery and development process. Our current clinical focus is on cystic fibrosis and cystinosis where we are advancing our lead drug product candidate ELX-02. Eloxx is headquartered in Waltham, MA with research and development operations in Rehovot, Israel. Eloxx Pharmaceuticals Ltd. (“Eloxx Limited”) was incorporated in Israel on September 17, 2013. The Company focuses its activity on the discovery, development and commercialization of compounds for the treatment of genetic diseases caused by nonsense mutations. In 2013, the Company entered into a license agreement (the “Technion Agreement”) with the Technion Research and Development Foundation Ltd. (“TRDF”). Reverse Merger On December 19, 2017, Sevion Therapeutics, Inc. (“Sevion”) acquired Eloxx Pharmaceuticals, Limited (“Private Eloxx” or “Eloxx Limited”) pursuant to a merger between the companies (the “Transaction” or “Reverse Merger”). Upon consummation of the Transaction (the “Closing”), Sevion adopted the business plan of Private Eloxx and discontinued the pursuit of Sevion’s business plan pre-Closing. In connection with the Transaction, Sevion agreed to acquire all of the outstanding capital stock of Private Eloxx in exchange for the issuance of an aggregate 20,316,656 shares of the Sevion’s common stock, par value $0.01 per share (the “Common Stock”), after giving effect to a 1-for-20 reverse split effected immediately prior to the Transaction. As a result of the Transaction, Private Eloxx became a wholly-owned subsidiary of Sevion. While Sevion was the legal acquirer in the transaction, Private Eloxx was deemed the accounting acquirer. Immediately after giving effect to the Transaction, on December 19, 2017, Sevion changed its name to Eloxx Pharmaceuticals, Inc. (“Eloxx” or the “Company”). The annual consolidated financial statements of the Company reflect the operations of Private Eloxx as the acquirer for accounting purposes, together with a deemed issuance of shares, equivalent to the shares held by the stockholders of the legal acquirer, Sevion, prior to the Transaction, and a recapitalization of the equity of the accounting acquirer. The annual consolidated financial statements include the accounts of the Company since the effective date of the reverse merger and the accounts of Private Eloxx since inception. Upon closing of the Reverse Merger, the Company assumed the obligations under outstanding warrants previously issued by Eloxx Limited to purchase its share capital and, in connection therewith, issued warrants to purchase 346,307 shares of the Company’s common stock to certain warrant holders of Eloxx Limited. In addition, upon closing of the Reverse Merger, Eloxx Limited assumed all of the outstanding obligations under the Eloxx 2013 Share Ownership and Option Plan (the “2013 Plan”) and, accordingly, the Company has reserved 2,307,738 shares of the Company’s common stock for issuance upon the exercise of such options. As part of the Company’s assumption of the outstanding options under the 2013 Plan, the Company also assumed the 2013 Plan and accordingly reserved 189,751 shares of the Company’s common stock for future grants. Immediately prior to the closing of the Reverse Merger the Company raised gross proceeds of $13.5 million at a price per share of $0.15 from accredited investors as a private placement. The amount was raised pursuant a share purchase agreement dated May 31, 2017, as amended between Eloxx Limited and a group of accredited investors, (“Eloxx SPA”). Under the Eloxx SPA and the first joinder thereunder executed on June 29, 2017, Eloxx Limited received gross proceeds of $15.0 million from the group of accredited investors. In accordance with the terms of the Eloxx SPA, each of the investors executed a separate subscription agreement with the Company for the total investment of an additional $15.0 million in exchange for the Company’s shares of common stock at a price per share of $0.15 immediately prior to the consummation of the Reverse Merger. With the consent of the parties, an amount of $1.5 million was invested by an accredited investor under the subscription agreement into Sevion. On August 2, 2017, Eloxx Limited raised under a second joinder to the Eloxx SPA, an additional aggregate amount of $8.0 million, half of the amount was invested in Eloxx Limited on August 2, 2017 and the remainder was invested in Eloxx Limited immediately prior to the consummation of the Reverse Merger but was deemed an investment in the Company’s share capital for the purpose of the exchange ratio under the Agreement. This private placement was made solely to “accredited investors,” as that term is defined in Regulation D under the Securities Act of 1933, as amended (the “Securities Act”), and was conducted in reliance on the exemption from registration afforded by Section 4(2), Rule 506 of Regulation D and Regulation S under the Securities Act, as amended, and corresponding provisions of state securities laws. Following the Reverse Merger and reverse stock split, and commencing December 20, 2017, the Company’s Common Stock symbol on OTCQB marketplace changed to “SVOND”, and subsequently changed to “ELOX” on January 19, 2018. Effective with the Reverse Merger each member of the Board of Directors of Eloxx Limited prior to the Reverse Merger was appointed to the Company’s Board of Directors. In addition, each officer of Eloxx Limited was reappointed as an officer of the Company. Also effective with the Reverse Merger, the Company’s Board affirmed its financial year end as December 31, 2017 to align with the fiscal year end of Eloxx Limited. Taurus Sublicense Agreement On December 18, 2017, the Company executed a binding term sheet with Taurus Biosciences Inc. (“Taurus”) pursuant to which the Company grants Taurus a worldwide exclusive, sublicensable, license to the antibody SVN-001 Liquidity As reflected in the accompanying audited consolidated financial statements, the Company has not generated revenue from the sale of any product and does not expect to generate significant revenue unless and until obtaining marketing approval and commercialization. As of December 31, 2017, the Company had cash and cash equivalents of $24.0 million. The Company expects its cash and cash equivalents will fund operations at least through the end of the first quarter of 2019 based on its current operating plans. The Company incurred a loss for the year ended December 31, 2017 of $21.2 million and had a negative cash flow from operating activities of $15.9 million during the year ended December 31, 2017. The accumulated deficit as of December 31, 2017 was $39.0 million. If we are unable to obtain funding, we could be forced to delay, reduce or eliminate our research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect our business prospects, or we may be unable to continue operations. The Company reported cash of $13.5 million in its September 30, 2017 balance sheet, and its use of cash in operations in Q4 2017 was $6.3 million. Q4 2017 research and development expense totaled $8.4 million which included $3.4 million in non-cash expense related to the Technion Agreement. Q4 2017 general & administrative expense totaled $2.2 million, transaction related costs were $0.7 million, and net loss was $10.6 million. The Company received net proceeds of $16.8 million in Q4 2017 related to completing its Series C financing.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”). Principles of Consolidation The consolidated financial statements include the accounts of the Company and its subsidiaries. Intercompany balances and transactions have been eliminated upon consolidation. Use of Estimates The preparation of the financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions. The Company’s management believes that the estimates, judgments and assumptions used are reasonable based upon information available at the time they are made. These estimates, judgments and assumptions can affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the dates of the financial statements, and the reported amounts of expenses during the reporting period. The Company evaluates estimates on an ongoing basis. Actual results could differ from those estimates. Foreign Currency Translation The functional currency of the Company is the U.S. dollar. Accordingly, monetary accounts maintained in currencies other than the dollar are re-measured re-measurement Cash and Cash Equivalents Cash equivalents are short-term highly liquid investments that are readily convertible to cash with original maturities of three months or less at the date of purchase to be cash equivalents. Restricted bank deposits At December 31, 2017, and 2016, restricted bank deposits consisted of guarantees related to the Company’s credit card and corporate facilities leases. Concentrations of credit risk Financial instruments that subject us to significant concentrations of credit risk consist primarily of cash. Substantially all of the Company’s cash is held at financial institutions that management believes to be of high-credit quality. Deposits with these financial institutions may exceed the amount of insurance provided on such deposits; however, these deposits may be redeemed upon demand and, therefore, bear minimal risk. The Company has no off-balance-sheet Property and Equipment Property and equipment are recorded at cost, less accumulated depreciation. Costs associated with maintenance and repairs are expensed as incurred. Depreciation expense is recognized using the straight-line method over the estimated useful lives: Useful Life (Years) Computers and software 3 years Office furniture and equipment 5 – 12 years Laboratory equipment 5 years Leasehold improvement Over the shorter of the expected lease term or estimated useful life Impairment of long-lived assets Property and equipment subject to amortization are reviewed for impairment in accordance with ASC Topic 360, “Accounting for the Impairment or Disposal of Long-Lived Assets,” whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted cash flows expected to be generated by the assets. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. The Company has not recorded any impairment losses to date. Legal and Other Contingencies The Company accounts for its contingent liabilities in accordance with ASC Topic 450 “Contingencies”. A provision is recorded when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. With respect to legal matters, provisions are reviewed and adjusted to reflect the impact of negotiations, estimated settlements, legal rulings, advice of legal counsel and other information and events pertaining to a particular matter. For the years ended December 31, 2017 and 2016, the Company was not a party to any litigation that could have a material adverse effect on the Company’s business, financial position, results of operations or cash flows (see also Note 9). Legal costs incurred in connection with loss contingencies are expensed as incurred. Severance Pay Eloxx Limited’s liability for severance pay is pursuant to Section 14 of the Severance Compensation Act, 1963 (“Section 14”) under Israeli law, pursuant to which all Eloxx Limited’s employees are included under Section 14, and are entitled only to monthly deposits, at a rate of 8.33% of their monthly salary, made in the employee’s name with insurance companies. Under Israeli employment law, payments in accordance with Section 14 release Eloxx Limited from any future severance payments in respect of those employees. The fund is made available to the employee at the time the employer-employee relationship is terminated, regardless of cause of termination. The severance pay liabilities and deposits under Section 14 are not reflected in the consolidated balance sheets as the severance pay risks have been irrevocably transferred to the severance funds. Severance expenses for the years ended December 31, 2017, 2016 and 2015 amounted to $64,000, $44,000 and $35,000, respectively. Research and Development Costs Research and development costs are expensed as incurred except royalty-bearing participation from the Israeli Innovation Authority (previously known as Office of the Chief Scientist) of the Ministry of Economy (“IIA”), as described in “Government Grants”. Research and development expenses are comprised of costs incurred in performing research and development activities, including salaries, stock-based compensation and benefits, facilities costs, depreciation, third-party license fees, and external costs of outside vendors engaged to conduct preclinical development activities and clinical trials. Research and development expenses include the Company’s costs of performing services in connection with its collaboration agreements and research grants. Nonrefundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are recognized as an expense as the goods are delivered or the related services are performed, or until it is no longer expected that the goods will be delivered, or the services rendered. Government Grants The Company receives royalty-bearing grants, which represents participation of IIA in approved programs for research and development. These amounts are recognized on the accrual basis as a reduction of research and development expenses as such expenses are incurred. Fair value of financial instruments: ASC Topic 820, “Fair Value Measurements and Disclosures” (“ASC 820”), defines fair value as the price that would be received to sell an asset or paid to transfer a liability (i.e., the “exit price”) in an orderly transaction between market participants at the measurement date. In determining fair value, the Company uses various valuation approaches. ASC 820 establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability developed based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the inputs as follows: Level 1 — Valuations based on quoted prices in active markets for identical assets that the Company has the ability to access. Level 2 — Valuations based on one or more quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3 — Valuations based on inputs that are unobservable and significant to the overall fair value measurement. The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The carrying amounts of cash and cash equivalents, restricted bank deposits, prepaids and other assets, trade payables and accrued expenses approximate their fair value due to the short-term maturities of such instruments. Stock-Based Compensation The Company accounts for stock-based compensation in accordance with ASC Topic 718, “Compensation-Stock Compensation”, (“ASC 718”), which requires companies to estimate the fair value of equity-based payment awards on the date of grant using an option-pricing model. The Company recognizes compensation expenses for the value of its awards granted based on the straight-line method over the requisite service period of each of the awards or over the implicit service period when a performance condition affects the vesting, and it is considered probable that the performance condition will be achieved. The Company estimates the fair value of stock options granted using the Binomial Option-Pricing Model (“Binomial Model”) which requires a number of assumptions, of which the most significant are the fair market value of the underlying Ordinary Shares, expected stock price volatility, suboptimal exercise factor and the expected option term. Expected volatility was calculated based upon historical volatilities of similar entities in the related sector index. The expected option term represents the period that the Company’s stock options are expected to be outstanding and is determined based on the simplified method until sufficient historical exercise data will support using expected life assumptions. The suboptimal exercise factor is estimated using historical option exercise information. The suboptimal exercise factor is the ratio by which the stock price must increase over the exercise price before employees are expected to exercise their stock options. The risk-free interest rate is based on the yield from U.S. treasury bonds with an equivalent term. The Company has historically not paid dividends and has no foreseeable plans to pay dividends. The fair value of ordinary shares underlying the options was determined by the Company’s Board of Directors with the assistance of an independent valuation firm. Because there has been no public market for the ordinary shares, the Board of Directors has determined fair value of the ordinary shares at the time of grant by considering a number of objective and subjective factors including data from other comparable companies, sales of series preferred shares to unrelated third parties, operating and financial performance, the lack of liquidity of capital stock and general and industry specific economic outlook, amongst other factors. The fair value of the underlying ordinary shares shall be determined by management until such time as the ordinary shares are listed on an established stock exchange, national market system or other quotation system. The Company determined that the Option Pricing Method (“OPM”) was the most appropriate method for allocating its enterprise value to determine the estimated fair value of its ordinary shares for valuations performed since its inception date and until June 30, 2017. Commencing June 30, 2017 and until the Closing of the Reverse Merger, the Company began using the Hybrid Method by combining the OPM and M&A scenario to determine the fair value of its ordinary shares. Following the closing of the Reverse Merger, the fair value of the Company’s common stock is determined based on the closing price on the OTCQB. Income taxes The Company account for income taxes in accordance with ASC Topic 740, “Income Taxes” (“ASC 740”) which prescribes the use of the liability method whereby deferred tax assets and liability account balances are determined based on differences between financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company provides a valuation allowance, if necessary, to reduce deferred tax assets to their estimated realizable value if it is more likely than not that a portion or all of the deferred tax assets will be realized. Based on ASC 740, a two-step Net Loss per Share The Company applies the two-class Topic 260-10, (“ASC 260-10”), No dividends were declared or paid during the reported periods. According to the provisions of ASC 260-10, Basic loss per share is computed by dividing the loss for the period applicable to ordinary shareholders by the weighted average number of ordinary shares outstanding during the period. In computing diluted income per share, basic earnings per share are adjusted to reflect the potential dilution that could occur upon the exercise of share options granted to grantees and upon conversion of shares and warrants issued to investors and service providers using the “treasury stock method”. For the years ended December 31, 2017, 2016 and 2015, all outstanding preferred stock, stock options, stock warrants and restricted stock have been excluded from the calculation of the diluted net loss per share as all such securities are anti-dilutive for all years presented (see Note 13). Recent Accounting Pronouncements adopted On March 30, 2016, the FASB issued ASU 2016-09, Recent Accounting Pronouncements not adopted yet In February 2016, the FASB issued ASU No. 2016-02, Leases. 2016-02 In November 2016, the FASB issued ASU 2016-18, 2016-18), beginning-of-period end-of-period In January 2017, the FASB issued ASU 2017-01 2017-01 2017-01 In July 2017, the FASB issued ASU 2017-11, which 2017-11

Reverse Merger

Reverse Merger	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Reverse Merger	3. Reverse Merger As described in Note 1: “Nature of the Business”, the Reverse Merger was accounted for as a reverse recapitalization which is outside the scope of ASC Topic 805, “Business Combinations” (“ASC 805”). Under reverse capitalization accounting, Eloxx Limited is considered the acquirer for accounting and financial reporting purposes and acquired the assets and assumed the liabilities of the Company. The assets acquired and liabilities assumed are reported at their historical amounts. The annual consolidated financial statements of the Company reflect the operations of the acquirer for accounting purposes together with a deemed issuance of shares, equivalent to the shares held by the former stockholders of the legal acquirer and a recapitalization of the equity of the accounting acquirer. The annual consolidated financial statements include the accounts of the Company since the effective date of the reverse capitalization and the accounts of Eloxx Limited since inception. The following summarizes the estimated fair value of the assets and liabilities assumed at the date of the Reverse Merger (in thousands): December 19, 2017 Cash and cash equivalents $ 123 Prepaid expenses and other current assets 220 Property, plant and equipment, net 39 Restricted bank deposits 6 Total assets acquired 388 Accounts payable (215 ) Accrued expenses (343 ) Total liabilities acquired (558 ) Total net liabilities acquired $ (170 ) Additionally, the Company incurred approximately $1.3 million in professional fees related to the Reverse Merger.

Prepaids and other current asse

Prepaids and other current assets	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Prepaids and other current assets	4. Prepaids and other current assets Prepaids and other current assets consisted of the following (in thousands): December 31 2017 2016 Government grants from IIA — 605 Other governmental agencies 88 221 Prepaid expenses 267 11 $ 355 $ 837

Property and Equipment, net

Property and Equipment, net	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment, net	5. Property and Equipment, net Property and equipment, net consisted of the following (in thousands): December 31 2017 2016 Cost: Computers and software $ 124 $ 54 Office furniture and equipment 118 2 Laboratory equipment 37 — Leasehold improvement 53 — 332 56 Accumulated depreciation 54 15 54 15 Property and equipment, net $ 278 $ 41 Depreciation expense was $39,000, $8,000 and $5,000 for the years ended December 31, 2017, 2016 and 2015, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued Expenses	6. Accrued Expenses Accrued expenses consisted of the following (in thousands): December 31, 2017 2016 Accrued payroll and related expenses $ 402 $ 393 Accrued research and development expenses 704 119 Accrued professional services 787 107 $ 1,893 $ 619

Convertible Loan

Convertible Loan	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Convertible Loan	7. Convertible Loan On January 26, 2017 (the “Closing Date”), the Company entered into a Convertible Loan Agreement (the “Agreement”) with five of its shareholders (the “Lenders”), pursuant to which the Company raised an aggregate amount of $2.5 million (the “Convertible Loan”). The Convertible Loan shall bear a 5% annual interest rate. According to the Agreement, the outstanding portion of the Convertible Loan (without accrued interest) should be automatically converted upon the consummation of equity investment by a third party of an aggregate amount of at least $5.0 million (the “Qualified Equity Investment”), prior to the lapse of two years from the Closing Date (the “Maturity Date”), into equity securities of the same class issued by the Company in such Qualified Equity Investment, in a conversion price which was equal to 80% of the price per share paid by the third party in such Qualified Equity Investment (the “Automatic Conversion”). In addition, upon the earlier of (i) Maturity Date or (ii) Event of Default as defined in the Agreement, the outstanding portion of the Convertible Loan (including accrued interest) should be converted into an equity investment of the then existing most senior class, at a conversion price per share which was equal to 65% of the original issue price per share applicable to such class. At the end of May 2017, the Lenders signed a waiver agreement pursuant to which they waived the potential discount as described above. In accordance with ASC Topic 815 “Derivatives and Hedging”, features related to convertible loans qualify as embedded derivative instruments at the date of issuance, since these are considered as stock settled debt. In determining fair value, the Company uses various valuation approaches. ASC 820 establishes a hierarchy for inputs used in measuring fair value. The embedded conversion feature is classified under level 3 in the hierarchy. The fair value assigned to the embedded conversion feature on the issuance dates amounted to $0.3 million. The embedded instruments are marked to market in each reporting period and changes are recorded in financial expenses. The discount is amortized using the effective interest over the loan period. On May 31, 2017, the Convertible Loan (without accrued interest) was converted into 825,213 Series C preferred stock, according to the price per share that was paid in the 2017 Share Purchase Agreement (see Note 10). During the year ended December 31, 2017, the Company recorded $0.7 million as financial and other expenses, net, as a result of changes in the embedded instruments. In connection with the conversion, the embedded instrument together with all accrued interest in the amount of $0.7 million and was classified to additional paid in capital. The following table presents reconciliations for the Company’s liabilities measured and recorded at fair value on a recurring basis, using significant unobservable inputs (in thousands): Significant Balance at January 26, 2017 $ (308 ) Amortization and revaluation embedded conversion feature (317 ) Conversion of convertible loan into Series C preferred stock 625 Balance at December 31, 2017 $ —

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Parties	8. Related Parties On August 29, 2013, the Company entered into an agreement (“Technion Agreement”) with TRDF, with respect to certain technology relating to aminoglycosides and the redesign of aminoglycosides for the treatment of human genetic diseases caused by premature stop mutations and further results of the research of the technology, in order to develop and commercialize products based on such technology. Under the agreement, TRDF shall provide the Company research services for an estimated annual payment of $0.1 million, to be agreed exactly by the parties prior to the beginning of each year of the research period. During the years ended December 31, 2017, 2016 and 2015, the Company recorded general and administrative expenses amounting to $7,000, $185,000 and $0, respectively, in relation to the TRDF reimbursement for the preparation, filling, prosecution and maintenance of TRDF patents rights related to Eloxx Limited. In addition, during the years ended December 31, 2017, 2016 and 2015 the Company recorded research and development expenses in relation to the TRDF amounting to $3,465,000, $33,000 and $58,000, respectively. As of December 31, 2017 and 2016, amounts recorded in accrued expenses were $25,000 and $185,000, respectively. In addition, TRDF shall grant the Company a license to use, market, sell or sub-license any non-royalty sub-license sub-licensed Moreover, upon the closing of an Exit Event which is not an Initial Public Offering (“IPO”), as defined in the Technion Agreement, TRDF shall be entitled to an amount equal to 3% of all non-refundable, non-contingent On August 9, 2017 the Company received a legal claims letter from TRDF regarding TRDF’s alleged entitlement to an exit fee in accordance with the Technion Agreement. The parties are in discussion regarding a settlement of the legal claim, whereby the Company would issue shares to TRDF representing approximately 2.1% of the outstanding shares of the Company representing fulfillment of the “exit clause.” Therefore, the Company has recorded a $3.4 million research and development expense with an offsetting adjustment to additional paid-in capital for the year ended December 31, 2017 related to this legal claim.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Operating Leases The Company entered into a lease agreement for office space in Rehovot, Israel for a period of three years commencing March 8, 2017 and until April 30, 2020 with annual lease payments in the amount of $0.1 million. The Company has an option to extend the lease for a term of two years. The Company entered into a lease agreement for laboratory space in Rehovot, Israel for a period of one year commencing March 8, 2017 and until March 8, 2018 with annual lease payments in the amount of $48,000. The Company has an option to extend the lease for a term of one year. The Company entered into a lease agreement for office space in Waltham, MA for a period of 37 months commencing November 15, 2017 and until December 17, 2020 with annual lease payments in the amount of $0.2 million. The Company has an option to extend the lease for a term of three years. Future minimum lease commitments as of December 31, 2017 were as follows: As of December 31, 2017 Total 2018 $ 258 2019 232 2020 186 $ 676 The Company recorded lease expenses in the amounts of $0.2 million for the year ended December 31, 2017 and $0.1 million for the each of the years ended December 31, 2016 and 2015. Royalty Commitments to the IIA Under the research and development agreements with the IIA and pursuant to applicable laws, the Company is required to pay royalties at the rate of 3% on sales to end customers of products developed with funds provided by the IIA, up to an amount equal to 100% of the IIA research and development grants received, linked to the dollar plus interest on the unpaid amount received based on the 12-month The Company received research and development grants from the IIA in the amounts of $0.9 million, $1.2 million, and $0.3 million for the years ended December 31, 2017, 2016 and 2015, respectively. As of December 31, 2017, the Company has not commenced the payment obligation of the royalties and has a contingent obligation with respect to royalty-bearing participation received or accrued, amounting to $2.7 million. Commitments to Scripps The Company assumed a license agreement with Scripps Research Institute through the Reverse Merger pursuant to which the Company is required to pay a 2% royalty of net sales. Commitments to TRDF Since August 29, 2013, the Company has had an ongoing agreement with TRDF. Refer to Note 8: Related Parties for further information.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Stockholders' Equity	10. Stockholders’ Equity For accounting purposes, all common stock, preferred stock, warrants, options to purchase common stock and loss per share amounts have been adjusted to give retroactive effect to the exchange ratio and reverse stock split for all periods presented in these consolidated financial statements. Preferred and Common Stock In April 2015, Eloxx Limited achieved a clinical milestone in connection with the share purchase agreement signed in 2013, pursuant to which, Eloxx Limited issued to investors 1,073,157 shares of Series A preferred stock with a par value of $0.01 for an aggregate amount of $0.9 million. In July 2015, Eloxx Limited entered into a Share Purchase Agreement (the “2015 SPA”) whereby Eloxx Limited issued to existing investors 1,002,049 shares of Series B-1 preferred stock with a par value of $0.01 and 1,503,068 warrants to purchase 1,503,068 shares of Series B-1 preferred stock with an exercise price of $3.11 for an aggregate gross amount of $3.1 million, representing a price per unit of $3.11 per share. In connection with the 2015 SPA, Eloxx Limited paid a contractor cash consideration of $0.1 million as a finder fee and granted 30,563 warrants to purchase 30,563 shares of Series B-1 preferred stock with an exercise price of $3.11 per share. In July 2015, one of Eloxx Limited’s employees exercised their 99,829 options with an exercise price of $0.01 per share to purchase 99,829 shares of common stock. In February 2016, Eloxx Limited entered into Shares Purchase Agreement (the “2016 SPA”) whereby Eloxx Limited issued to existing investors 1,929,676 shares of Series B-1 preferred stock with a par value of $0.01 and 2,894,519 warrants to purchase 2,894,519 shares of Series B-1 preferred stock with an exercise price of $3.11 per share for an aggregate gross amount of $6.0 million. In connection with the 2016 SPA, Eloxx Limited paid a contractor cash consideration of $0.2 million as finder fee and granted 48,242 warrants to purchase 48,242 shares of Series B-1 preferred stock with an exercise price of $3.11 per share. In August 2016, Technion Investment Opportunities Fund L.P (the “TIOF) and TRDF exercised 124,786 and 311,964 warrants, respectively, to purchase shares of Series A preferred stock at an exercise price of $0.80 per share, respectively, for total consideration of $0.4 million. In September 2016, Eloxx Limited achieved a milestone in connection with the Share Purchase Agreement signed in 2014 (“2014 SPA”), pursuant to which, Eloxx Limited paid a $0.1 million milestone payment and issued to investors 1,174,138 shares of Series B-1 preferred stock with a par value of $0.01 and 587,072 warrants to purchase 587,072 shares of Series B-1 preferred stock for an aggregate amount of $3.7 million. In connection with the 2014 SPA milestone, Eloxx Limited paid a contractor cash consideration of $0.1 million as a finder fee and granted 36,593 warrants to purchase 36,593 shares of Series B-1 preferred stock with exercise price of $3.11 per share. On May 22, 2017, Eloxx Limited entered into a Share Purchase Agreement (the “2017 SPA”) (and subsequently on joinder agreements) with certain existing and new investors, whereby, an aggregate gross amount of $21.5 million, which included the conversion of the loan (as detailed in Note 7), was received by Eloxx Limited in exchange for the issuance of 7,136,289 shares of Series C preferred stock with a par value of $0.01 with the initial closing, of which 39,293 were issued as a result of the anti-dilution effect of the Reverse Merger. The related issuance costs were $0.6 million. In connection with the 2017 SPA, the Company granted 142,524 warrants to purchase 142,524 shares of Series C preferred stock to certain service providers of as finder fee compensation. Upon the closing of the Reverse Merger the Company issued 6,333,333 shares of common stock related to the closing of the 2017 SPA with a par value of $0.01 for an aggregate gross amount of $17.5. Additionally, Sevion raised $1.5 million prior to the Reverse Merger. The related issuance costs for these transactions was $0.5 million. Warrants As of December 31, 2017, the Company had 480,049 outstanding warrants to purchase 480,049 shares of the Company’s common stock. The table below summarizes the outstanding warrants as of December 31, 2017: Amount Weighted Expiration Date 64,374 0.800 12/19/2022 59,415 3.030 12/19/2022 60,832 3.000 12/19/2022 22,282 3.029 12/19/2022 151,984 3.109 12/19/2022 48,252 4.664 12/19/2022 68,434 8.000 1/27/2018 4,474 40.000 5/16/2019 2 520.000 11/17/2020 480,049

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	11. Stock-Based Compensation The Company has two equity compensation plans; the Company has a 2008 Plan and Eloxx Limited has a 2013 plan, both are explained in detail below. In December 2008, the Company adopted the 2008 Incentive Compensation Plan (the “2008 Plan”), which provides for the grant of stock options, stock grants and stock purchase rights to certain designated employees and certain other persons performing services for the Company, as designated by the Company’s Board of Directors. Pursuant to the 2008 Plan, an aggregate of 245,884 shares of common stock has been reserved for issuance. On January 1 of each calendar year beginning with the calendar year 2015, the share reserve will automatically increase by 5% of the fully-diluted equity outstanding on the immediately preceding December 31, up to an annual maximum of 75,000 shares of common stock, provided that the aggregate number of shares subject to outstanding awards will not exceed 25% of the fully-diluted equity outstanding. Consequently, the pool of options was increased by additional 126,051 shares of common stock. The terms and vesting schedules for share-based awards vary by type of grant and the employment status of the grantee. Generally, the awards vest based upon time-based conditions or achievement of specified goals and milestones. As of December 31, 2017, 116,466 Common Stock are available for future grant under the 2008 Plan. In December 2013, Eloxx Limited’s Board of Directors adopted the 2013 Share Ownership and Option Plan in accordance with section 102 and 3(i) of the Israeli Income Tax Ordinance (the “2013 Plan”). Under the 2013 Plan, options to purchase ordinary shares of Eloxx Limited or ordinary shares of Eloxx Limited may be granted to employees, officers, directors, service providers and consultants of Eloxx Limited Each option granted can be exercised for one ordinary share of Eloxx Limited. Options granted generally become fully exercisable after a two to four-year vesting period and expire no later than ten years from the date of grant. Any option forfeited or cancelled before expiration becomes available for future grants under the 2013 Plan until the tenth anniversary of the 2013 Plan, after which no further grants under the 2013 Plan are permissible. On April 21, 2015, Eloxx Limited’s Board of Directors adopted the US Share Ownership and Option Appendix under 2013 Plan pursuant to which Eloxx Limited may grant options to purchase its ordinary shares to U.S. grantees of Eloxx Limited or any of its parent or subsidiary companies. Upon the closing of the Reverse Merger, the Company assumed the 2013 Plan and all outstanding options thereunder and thereafter the 2013 Plan and any options or shares previously granted thereunder were replaced with options to purchase or shares of our common stock. As of December 31, 2017, the of the 2013 Plan amounted to 2,473,255 shares of common stock and 119,762 shares of Common Stock were available for future grant under the 2013 Plan. Transactions related to the grant of options to employees and directors under the 2008 Plan during the year ended December 31, 2017, were as follows: Amount Weighted Weighted Aggregate Options outstanding at the closing of the Reverse Merger 215,723 $ 28.93 7.80 $ 61,358 Options outstanding at end of year 215,723 $ 28.93 7.80 $ 338,056 Options exercisable at end of year 215,723 $ 28.93 7.80 $ 338,056 Transactions related to the grant of options to employees and directors under the 2013 Plan during the year ended December 31, 2017, were as follows: Amount Weighted Weighted Aggregate Options outstanding at beginning of year 1,948,154 $ 0.47 7.93 $ 1,571,406 Granted 582,961 5.40 Exercised (16,669 ) 0.96 Forfeited (177,720 ) 0.98 Options outstanding at end of year 2,336,726 $ 1.82 7.12 $ 14,835,970 Options exercisable at end of year 1,624,407 $ 0.36 6.04 $ 12,408,281 The aggregate intrinsic value represents the total intrinsic value (the difference between the deemed fair value of the Company’s Common Stock on the last day of fiscal year 2017 and the exercise price, multiplied by the number of in-the-money The weighted average grant date fair value of the options granted during the years ended December 31, 2017, 2016 and 2015 were $3.68, $0.14 and $0.17, respectively. The following table presents the assumptions used to estimate the fair values of the options granted in the period presented: December 31, 2017 2016 2015 Dividend yield 0% 0% 0% Volatility 87.17%-116.69% 64.46%-105.57% 73.70%-88.72% Risk free interest 1.22%-2.5% 0.47%-2.35% 0.25%-1.87% Contractual term (years) 10 10 10 Forfeiture rate post-vesting 10% 10% 10% Suboptimal exercise 2.3 2.3 2.3 As of December 31, 2017, there was $2.1 million of total unrecognized compensation cost related to non-vested stock The total equity-based compensation expense related to all of the Company’s equity-based awards were recognized as follows: Year ended 2017 2016 2015 Research and development $ 39 $ 61 $ 68 General and administrative (1) 62 17 24 Total stock-based compensation expenses $ 101 $ 78 $ 92 (1) Including expenses of $19,000 in connection with restricted shares that were granted during the year ended December 31, 2017. The Company issued an inducement award outside of the 2008 Plan and 2013 Plan to the Company’s Chief Executive Officer in the form of an option to purchase 22,427 shares of the Company’s common stock with an exercise price per share equal to $8.00, and an award of restricted stock units for 22,427 shares of the Company’s common stock (collectively the “Performance Option Awards”). Subject to continued service through the vesting date, the Performance Option Awards will vest and become immediately exercisable upon the date that marks the first successful completion of a Phase-2B In addition, the Company issued an inducement award outside of the 2008 Plan and 2013 Plan to the Company’s Chief Executive Officer in the form of an option to purchase 640,785 shares of the Company’s common stock with an exercise price per share equal to $8.00, and an award of restricted stock units for 640,785 shares of the Company’s common stock (collectively the “Time-Vesting Awards”). Subject to continued service through the vesting date, 1/3 of the Time-Vesting Awards will vest and become immediately exercisable on the first anniversary of the effective date, with an additional 1/12 of the Time-Vesting Awards vesting on each quarterly anniversary of the effective date, provided that vesting of the Time-Vesting Awards shall be subject to acceleration following the achievement of certain milestones.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes The Company is subject to income taxes in the United States and Israel. In general, the U.S. federal and state income tax returns remain open to examination by taxing authorities for tax years beginning in June 30, 2014 to present. The Israeli income tax returns remain open to examination beginning in 2013 to present. However, if and when the Company claims net operating loss (“NOL”) carryforwards from any prior years against future taxable income, those losses may be examined by the taxing authorities. The United States enacted the Tax Cuts and Jobs Act (“Tax Act”) on December 22, 2017, most provisions of which will take effect starting in years beginning after December 31, 2017. The Tax Act makes substantial changes to U.S. taxation of corporations, including lowering the U.S. federal corporate income tax rate from 34% to 21%. The effect on deferred tax assets and liabilities of a change in law or tax rates is recognized in income in the period that includes the enactment date. The Tax Act also includes a provision designed to currently tax global intangible low-taxed After the enactment of the Tax Act, the SEC issued Staff Accounting Bulletin No. 118 (“SAB 118”) to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Act. We have calculated an estimate of the impact of the Tax Act in our year-end one-year Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. A deferred tax liability or asset shall be recognized for all of the Company’s estimated future tax effects attributable to temporary differences and carryforwards, unless an exception applies. A common exception for businesses that operate in multiple jurisdictions is a temporary difference that is essentially permanent in duration related to the excess of the amount for financial reporting over the tax basis of an investment attributable to unremitted earnings in a foreign subsidiary. However, there are no or trivial unremitted earnings in foreign jurisdictions, so no provision for deferred taxes thereupon is required for the Company. Significant components of the Company’s deferred tax assets are as follows (in thousands): December 31, 2017 2016 Deferred tax assets: Net operation loss carryforward $ 23,689 $ 2,811 Stock-based compensation 1,125 — Reserves and allowances 11 17 U.S. tax credits and other 714 — Research and development 2,604 1,195 Net deferred tax asset before valuation allowance 28,143 4,023 Valuation allowance (28,143 ) (4,023 ) Net deferred tax asset $ — $ — In assessing the realization of deferred tax assets, management considers whether it is more likely than not that all or some portion of the deferred tax assets will not be realized. The ultimate realization of the deferred tax assets is dependent upon the generation of future taxable income during the periods in which temporary differences are deductible and net operating losses are utilized. Based on consideration of these factors, the Company recorded a full valuation allowance at December 31, 2017 and 2016. As of December 31, 2017 and 2016, we have provided a valuation allowance of approximately $28.1 million and $4.0 million, respectively, on U.S. federal and state and Israeli tax jurisdiction deferred tax assets to reduce the amount of these assets to zero. The net change in our valuation allowance was an increase of $24.1 million for the year ended December 31, 2017 of which $30.2 million was related to the Reverse Merger of Sevion on December 19, 2017, that was partially offset by a $10.2 million decrease related to the reduction in the U.S. federal corporate tax rate on December 22, 2017. The remaining $4.1 million increase was primarily related to losses generated in the current period. As of December 31, 2017, we had U.S. federal and state NOL carryforwards of $77.2 million and $27.4 million, respectively, and federal research tax credit carryforwards of $0.7 million. Our U.S. net operating loss carryforwards will begin to expire, if not utilized, beginning in 2019 through 2037, and the research tax credits will expire beginning in 2027 through 2037. These NOL carryforwards could expire unused and be unavailable to offset future income tax liabilities. Under the newly enacted Tax Act, federal net operating losses incurred in 2018 and in future years may be carried forward indefinitely, but the deductibility of such federal net operating losses is limited. It is uncertain if and to what extent various states will conform to the newly enacted federal tax law. In addition, under Section 382 of the Code and corresponding provisions of state law, if a corporation undergoes an “ownership change,” which is generally defined as a greater than 50 percent change, by value, in its equity ownership over a three-year period, the corporation’s ability to use its pre-change pre-change pre-change The components of income (loss) before taxes on income are as follows (in thousands): Year ended December 31, 2017 2016 2015 U.S. $ (21 ) $ 44 $ 16 Israel (21,145 ) (9,883 ) (6,418 ) Income (loss) before taxes on income $ (21,166 ) $ (9,839 ) $ (6,402 ) Taxes on income during the years ended December 31, 2017 and 2016 are comprised from taxes incurred as a result of the implementation of the cost-plus method between the Company and its subsidiary were immaterial. The main reconciling item between the statutory tax rate of the Company and the effective tax rate is the recognition of valuation allowances in respect to deferred taxes relating to accumulated net operating losses carried forward and temporary differences due to the uncertainty of the realization of such deferred taxes.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Loss Per Share	13. Net Loss Per Share The loss and the weighted average number of shares used in computing basic and diluted net loss per share for the years ended December 31, 2017, 2016 and 2015, is as follows (amounts in thousands, except share numbers): Year ended December 31, 2017 2016 2015 Numerator: Net loss $ 21,214 $ 9,847 $ 6,406 Dividends accumulated for the period (1) 2,404 1,100 516 Net loss available to stockholders of Common Stock $ 23,618 $ 10,947 $ 6,922 Denominator: Shares used in computing net loss per share of Common Stock, basic and diluted 4,976,377 4,205,277 4,148,389 Net loss per share of Common Stock, basic and diluted $ 4.75 $ 2.60 $ 1.67 (1) The net loss used for the computation of basic and diluted net loss per share include 8% per share per annum compounded annually which was related to distributions for preferred stockholders of Eloxx Limited. On December 19, 2017 in conjunction with the Reverse Merger all preferred shares were converted to common shares. The total weighted average numbers of shares related to outstanding preferred stock, stock options under the 2008 Plan and 2013 Plan, stock warrants and restricted shares that have been excluded from the calculation of the diluted net loss per share due to their anti-dilutive effect was 19,027,306, 12,746,823 and 6,778,980 for the years ended December 31, 2017, 2016 and 2015, respectively.

Financial and Other Expenses, n

Financial and Other Expenses, net	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Financial and Other Expenses, net	14. Financial and Other Expenses, net Financial and other expenses consisted of the following (in thousands): Year ended 2017 2016 2015 Exchange rate differences 156 7 122 Amortization and revaluation of embedded conversion feature in respect to convertible loan 625 — — Interest expenses in respect to convertible loan 43 — — Total financial and other expense, net 824 7 122

Segment and Geographic Informat

Segment and Geographic Information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment and Geographic Information	15. Segment and Geographic Information Operating segments are defined as components of an enterprise (business activity from which it earns revenue and incurs expenses) about which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the Chief Executive Officer. The chief operating decision maker reviews consolidated operating results to make decisions about allocating resources and assessing performance for the entire company. The Company views its operations and manages its business as one operating segment; however, it operates in two geographic regions: United States (Waltham, MA) and Israel (Rehovot).

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	16. Subsequent Events On January 10, 2018, the Company filed a Registration Statement on Form S-8

Summary of Significant Accoun24

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”).
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its subsidiaries. Intercompany balances and transactions have been eliminated upon consolidation.
Use of Estimates	Use of Estimates The preparation of the financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions. The Company’s management believes that the estimates, judgments and assumptions used are reasonable based upon information available at the time they are made. These estimates, judgments and assumptions can affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the dates of the financial statements, and the reported amounts of expenses during the reporting period. The Company evaluates estimates on an ongoing basis. Actual results could differ from those estimates.
Foreign Currency Translation	Foreign Currency Translation The functional currency of the Company is the U.S. dollar. Accordingly, monetary accounts maintained in currencies other than the dollar are re-measured re-measurement
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents are short-term highly liquid investments that are readily convertible to cash with original maturities of three months or less at the date of purchase to be cash equivalents.
Restricted bank deposits	Restricted bank deposits At December 31, 2017, and 2016, restricted bank deposits consisted of guarantees related to the Company’s credit card and corporate facilities leases.
Concentrations of credit risk	Concentrations of credit risk Financial instruments that subject us to significant concentrations of credit risk consist primarily of cash. Substantially all of the Company’s cash is held at financial institutions that management believes to be of high-credit quality. Deposits with these financial institutions may exceed the amount of insurance provided on such deposits; however, these deposits may be redeemed upon demand and, therefore, bear minimal risk. The Company has no off-balance-sheet
Property and Equipment	Property and Equipment Property and equipment are recorded at cost, less accumulated depreciation. Costs associated with maintenance and repairs are expensed as incurred. Depreciation expense is recognized using the straight-line method over the estimated useful lives: Useful Life (Years) Computers and software 3 years Office furniture and equipment 5 – 12 years Laboratory equipment 5 years Leasehold improvement Over the shorter of the expected lease term or estimated useful life
Impairment of long-lived assets	Impairment of long-lived assets Property and equipment subject to amortization are reviewed for impairment in accordance with ASC Topic 360, “Accounting for the Impairment or Disposal of Long-Lived Assets,” whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted cash flows expected to be generated by the assets. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. The Company has not recorded any impairment losses to date.
Legal and Other Contingencies	Legal and Other Contingencies The Company accounts for its contingent liabilities in accordance with ASC Topic 450 “Contingencies”. A provision is recorded when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. With respect to legal matters, provisions are reviewed and adjusted to reflect the impact of negotiations, estimated settlements, legal rulings, advice of legal counsel and other information and events pertaining to a particular matter. For the years ended December 31, 2017 and 2016, the Company was not a party to any litigation that could have a material adverse effect on the Company’s business, financial position, results of operations or cash flows (see also Note 9). Legal costs incurred in connection with loss contingencies are expensed as incurred.
Severance Pay	Severance Pay Eloxx Limited’s liability for severance pay is pursuant to Section 14 of the Severance Compensation Act, 1963 (“Section 14”) under Israeli law, pursuant to which all Eloxx Limited’s employees are included under Section 14, and are entitled only to monthly deposits, at a rate of 8.33% of their monthly salary, made in the employee’s name with insurance companies. Under Israeli employment law, payments in accordance with Section 14 release Eloxx Limited from any future severance payments in respect of those employees. The fund is made available to the employee at the time the employer-employee relationship is terminated, regardless of cause of termination. The severance pay liabilities and deposits under Section 14 are not reflected in the consolidated balance sheets as the severance pay risks have been irrevocably transferred to the severance funds. Severance expenses for the years ended December 31, 2017, 2016 and 2015 amounted to $64,000, $44,000 and $35,000, respectively.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred except royalty-bearing participation from the Israeli Innovation Authority (previously known as Office of the Chief Scientist) of the Ministry of Economy (“IIA”), as described in “Government Grants”. Research and development expenses are comprised of costs incurred in performing research and development activities, including salaries, stock-based compensation and benefits, facilities costs, depreciation, third-party license fees, and external costs of outside vendors engaged to conduct preclinical development activities and clinical trials. Research and development expenses include the Company’s costs of performing services in connection with its collaboration agreements and research grants. Nonrefundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are recognized as an expense as the goods are delivered or the related services are performed, or until it is no longer expected that the goods will be delivered, or the services rendered.
Government Grants	Government Grants The Company receives royalty-bearing grants, which represents participation of IIA in approved programs for research and development. These amounts are recognized on the accrual basis as a reduction of research and development expenses as such expenses are incurred.
Fair value of financial instruments	Fair value of financial instruments: ASC Topic 820, “Fair Value Measurements and Disclosures” (“ASC 820”), defines fair value as the price that would be received to sell an asset or paid to transfer a liability (i.e., the “exit price”) in an orderly transaction between market participants at the measurement date. In determining fair value, the Company uses various valuation approaches. ASC 820 establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability developed based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the inputs as follows: Level 1 — Valuations based on quoted prices in active markets for identical assets that the Company has the ability to access. Level 2 — Valuations based on one or more quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3 — Valuations based on inputs that are unobservable and significant to the overall fair value measurement. The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The carrying amounts of cash and cash equivalents, restricted bank deposits, prepaids and other assets, trade payables and accrued expenses approximate their fair value due to the short-term maturities of such instruments.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation in accordance with ASC Topic 718, “Compensation-Stock Compensation”, (“ASC 718”), which requires companies to estimate the fair value of equity-based payment awards on the date of grant using an option-pricing model. The Company recognizes compensation expenses for the value of its awards granted based on the straight-line method over the requisite service period of each of the awards or over the implicit service period when a performance condition affects the vesting, and it is considered probable that the performance condition will be achieved. The Company estimates the fair value of stock options granted using the Binomial Option-Pricing Model (“Binomial Model”) which requires a number of assumptions, of which the most significant are the fair market value of the underlying Ordinary Shares, expected stock price volatility, suboptimal exercise factor and the expected option term. Expected volatility was calculated based upon historical volatilities of similar entities in the related sector index. The expected option term represents the period that the Company’s stock options are expected to be outstanding and is determined based on the simplified method until sufficient historical exercise data will support using expected life assumptions. The suboptimal exercise factor is estimated using historical option exercise information. The suboptimal exercise factor is the ratio by which the stock price must increase over the exercise price before employees are expected to exercise their stock options. The risk-free interest rate is based on the yield from U.S. treasury bonds with an equivalent term. The Company has historically not paid dividends and has no foreseeable plans to pay dividends. The fair value of ordinary shares underlying the options was determined by the Company’s Board of Directors with the assistance of an independent valuation firm. Because there has been no public market for the ordinary shares, the Board of Directors has determined fair value of the ordinary shares at the time of grant by considering a number of objective and subjective factors including data from other comparable companies, sales of series preferred shares to unrelated third parties, operating and financial performance, the lack of liquidity of capital stock and general and industry specific economic outlook, amongst other factors. The fair value of the underlying ordinary shares shall be determined by management until such time as the ordinary shares are listed on an established stock exchange, national market system or other quotation system. The Company determined that the Option Pricing Method (“OPM”) was the most appropriate method for allocating its enterprise value to determine the estimated fair value of its ordinary shares for valuations performed since its inception date and until June 30, 2017. Commencing June 30, 2017 and until the Closing of the Reverse Merger, the Company began using the Hybrid Method by combining the OPM and M&A scenario to determine the fair value of its ordinary shares. Following the closing of the Reverse Merger, the fair value of the Company’s common stock is determined based on the closing price on the OTCQB.
Income taxes	Income taxes The Company account for income taxes in accordance with ASC Topic 740, “Income Taxes” (“ASC 740”) which prescribes the use of the liability method whereby deferred tax assets and liability account balances are determined based on differences between financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company provides a valuation allowance, if necessary, to reduce deferred tax assets to their estimated realizable value if it is more likely than not that a portion or all of the deferred tax assets will be realized. Based on ASC 740, a two-step
Net Loss per Share	Net Loss per Share The Company applies the two-class Topic 260-10, (“ASC 260-10”), No dividends were declared or paid during the reported periods. According to the provisions of ASC 260-10, Basic loss per share is computed by dividing the loss for the period applicable to ordinary shareholders by the weighted average number of ordinary shares outstanding during the period. In computing diluted income per share, basic earnings per share are adjusted to reflect the potential dilution that could occur upon the exercise of share options granted to grantees and upon conversion of shares and warrants issued to investors and service providers using the “treasury stock method”. For the years ended December 31, 2017, 2016 and 2015, all outstanding preferred stock, stock options, stock warrants and restricted stock have been excluded from the calculation of the diluted net loss per share as all such securities are anti-dilutive for all years presented (see Note 13).
Recent Accounting Pronouncements adopted	Recent Accounting Pronouncements adopted On March 30, 2016, the FASB issued ASU 2016-09,
Recent Accounting Pronouncements not adopted yet	Recent Accounting Pronouncements not adopted yet In February 2016, the FASB issued ASU No. 2016-02, Leases. 2016-02 In November 2016, the FASB issued ASU 2016-18, 2016-18), beginning-of-period end-of-period In January 2017, the FASB issued ASU 2017-01 2017-01 2017-01 In July 2017, the FASB issued ASU 2017-11, which 2017-11

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Useful Lives of Principal Classes of Assets	Depreciation expense is recognized using the straight-line method over the estimated useful lives: Useful Life (Years) Computers and software 3 years Office furniture and equipment 5 – 12 years Laboratory equipment 5 years Leasehold improvement Over the shorter of the expected lease term or estimated useful life

Reverse Merger (Tables)

Reverse Merger (Tables)	12 Months Ended
	Dec. 31, 2017
Eloxx Limited [Member]
Estimated Fair Values of the Assets Acquired and Liabilities Assumed	The following summarizes the estimated fair value of the assets and liabilities assumed at the date of the Reverse Merger (in thousands): December 19, 2017 Cash and cash equivalents $ 123 Prepaid expenses and other current assets 220 Property, plant and equipment, net 39 Restricted bank deposits 6 Total assets acquired 388 Accounts payable (215 ) Accrued expenses (343 ) Total liabilities acquired (558 ) Total net liabilities acquired $ (170 )

Prepaids and other current as27

Prepaids and other current assets (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Prepaids and Other Current Assets	Prepaids and other current assets consisted of the following (in thousands): December 31 2017 2016 Government grants from IIA — 605 Other governmental agencies 88 221 Prepaid expenses 267 11 $ 355 $ 837

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and equipment, net	Property and equipment, net consisted of the following (in thousands): December 31 2017 2016 Cost: Computers and software $ 124 $ 54 Office furniture and equipment 118 2 Laboratory equipment 37 — Leasehold improvement 53 — 332 56 Accumulated depreciation 54 15 54 15 Property and equipment, net $ 278 $ 41

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued expenses	Accrued expenses consisted of the following (in thousands): December 31, 2017 2016 Accrued payroll and related expenses $ 402 $ 393 Accrued research and development expenses 704 119 Accrued professional services 787 107 $ 1,893 $ 619

Convertible Loan (Tables)

Convertible Loan (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Reconciliations for Liabilities Measured and Recorded at Fair Value on Recurring Basis, Using Significant Unobservable Inputs	The following table presents reconciliations for the Company’s liabilities measured and recorded at fair value on a recurring basis, using significant unobservable inputs (in thousands): Significant Balance at January 26, 2017 $ (308 ) Amortization and revaluation embedded conversion feature (317 ) Conversion of convertible loan into Series C preferred stock 625 Balance at December 31, 2017 $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments	Future minimum lease commitments as of December 31, 2017 were as follows: As of December 31, 2017 Total 2018 $ 258 2019 232 2020 186 $ 676

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Summary of Warrants Outstanding	The table below summarizes the outstanding warrants as of December 31, 2017: Amount Weighted Expiration Date 64,374 0.800 12/19/2022 59,415 3.030 12/19/2022 60,832 3.000 12/19/2022 22,282 3.029 12/19/2022 151,984 3.109 12/19/2022 48,252 4.664 12/19/2022 68,434 8.000 1/27/2018 4,474 40.000 5/16/2019 2 520.000 11/17/2020 480,049

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Assumptions Used to Estimate Fair Values of Options Granted	The following table presents the assumptions used to estimate the fair values of the options granted in the period presented: December 31, 2017 2016 2015 Dividend yield 0% 0% 0% Volatility 87.17%-116.69% 64.46%-105.57% 73.70%-88.72% Risk free interest 1.22%-2.5% 0.47%-2.35% 0.25%-1.87% Contractual term (years) 10 10 10 Forfeiture rate post-vesting 10% 10% 10% Suboptimal exercise 2.3 2.3 2.3
Summary of Allocated Stock-based Compensation Expense	The total equity-based compensation expense related to all of the Company’s equity-based awards were recognized as follows: Year ended 2017 2016 2015 Research and development $ 39 $ 61 $ 68 General and administrative (1) 62 17 24 Total stock-based compensation expenses $ 101 $ 78 $ 92 (1) Including expenses of $19,000 in connection with restricted shares that were granted during the year ended December 31, 2017.
2008 Plan [Member]
Transactions Related to Grant of Options to Employees and Directors	Transactions related to the grant of options to employees and directors under the 2008 Plan during the year ended December 31, 2017, were as follows: Amount Weighted Weighted Aggregate Options outstanding at the closing of the Reverse Merger 215,723 $ 28.93 7.80 $ 61,358 Options outstanding at end of year 215,723 $ 28.93 7.80 $ 338,056 Options exercisable at end of year 215,723 $ 28.93 7.80 $ 338,056
2013 Plan [Member]
Transactions Related to Grant of Options to Employees and Directors	Transactions related to the grant of options to employees and directors under the 2013 Plan during the year ended December 31, 2017, were as follows: Amount Weighted Weighted Aggregate Options outstanding at beginning of year 1,948,154 $ 0.47 7.93 $ 1,571,406 Granted 582,961 5.40 Exercised (16,669 ) 0.96 Forfeited (177,720 ) 0.98 Options outstanding at end of year 2,336,726 $ 1.82 7.12 $ 14,835,970 Options exercisable at end of year 1,624,407 $ 0.36 6.04 $ 12,408,281

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Deferred Income Tax Assets	Significant components of the Company’s deferred tax assets are as follows (in thousands): December 31, 2017 2016 Deferred tax assets: Net operation loss carryforward $ 23,689 $ 2,811 Stock-based compensation 1,125 — Reserves and allowances 11 17 U.S. tax credits and other 714 — Research and development 2,604 1,195 Net deferred tax asset before valuation allowance 28,143 4,023 Valuation allowance (28,143 ) (4,023 ) Net deferred tax asset $ — $ —
Components of Income (Loss) Before Taxes	The components of income (loss) before taxes on income are as follows (in thousands): Year ended December 31, 2017 2016 2015 U.S. $ (21 ) $ 44 $ 16 Israel (21,145 ) (9,883 ) (6,418 ) Income (loss) before taxes on income $ (21,166 ) $ (9,839 ) $ (6,402 )

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Loss and Weighted Average Number of Shares Used in Computing Basic and Diluted Net Loss Per Share	The loss and the weighted average number of shares used in computing basic and diluted net loss per share for the years ended December 31, 2017, 2016 and 2015, is as follows (amounts in thousands, except share numbers): Year ended December 31, 2017 2016 2015 Numerator: Net loss $ 21,214 $ 9,847 $ 6,406 Dividends accumulated for the period (1) 2,404 1,100 516 Net loss available to stockholders of Common Stock $ 23,618 $ 10,947 $ 6,922 Denominator: Shares used in computing net loss per share of Common Stock, basic and diluted 4,976,377 4,205,277 4,148,389 Net loss per share of Common Stock, basic and diluted $ 4.75 $ 2.60 $ 1.67 (1) The net loss used for the computation of basic and diluted net loss per share include 8% per share per annum compounded annually which was related to distributions for preferred stockholders of Eloxx Limited. On December 19, 2017 in conjunction with the Reverse Merger all preferred shares were converted to common shares.

Financial and Other Expenses,36

Financial and Other Expenses, net (Tables)	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Schedule of Financial and Other Expenses	Financial and other expenses consisted of the following (in thousands): Year ended 2017 2016 2015 Exchange rate differences 156 7 122 Amortization and revaluation of embedded conversion feature in respect to convertible loan 625 — — Interest expenses in respect to convertible loan 43 — — Total financial and other expense, net 824 7 122

Nature of the Business - Additi

Nature of the Business - Additional Information (Detail)	Dec. 19, 2017USD ($)$ / sharesshares	Dec. 18, 2017	Aug. 02, 2017USD ($)	Jun. 29, 2017USD ($)$ / shares	Aug. 29, 2013USD ($)	Jul. 31, 2015shares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2017USD ($)Diseases$ / sharesshares	Dec. 31, 2016USD ($)$ / shares	Dec. 31, 2015USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2014USD ($)
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Number of rare diseases | Diseases								1,800
Common stock, par value | $ / shares							$ 0.01	$ 0.01	$ 0.01
Warrants issued to purchase common stock to certain warrant holders | shares							480,049	480,049
Share issued upon exercise of stock option | shares						99,829
Issuance of Common Stock								$ 17,006,000
Cash and cash equivalents							$ 24,049,000	24,049,000	$ 2,212,000	$ 1,370,000		$ 1,737,000
Net loss							(10,600,000)	(21,214,000)	(9,847,000)	(6,406,000)
Net cash used in operating activities							6,300,000	(15,935,000)	(8,844,000)	(5,735,000)
Accumulated deficit							(38,960,000)	(38,960,000)	(17,746,000)
Cash											$ 13,500,000
Research and development expense							8,400,000	16,398,000	8,986,000	5,842,000
Selling, general and administrative expense							2,200,000	3,992,000	854,000	442,000
Transaction related cost							700,000
Technion Research and Development Foundation Ltd [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Research and development expense					$ 100,000			$ 3,400,000
Share Purchase Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Share price | $ / shares				$ 0.15
Issuance of Common Stock				$ 15,000,000
Subscription Agreement [Member] | Eloxx SPA [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Share price | $ / shares				$ 0.15
Issuance of Common Stock	$ 1,500,000		$ 8,000,000	$ 15,000,000
Taurus Sublicense Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Royalty payment as percentage of net sales		2.00%
Scripps Research Institute License Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Royalty payment as percentage of net sales		2.00%						2.00%
Technion Agreement [Member] | Technion Research and Development Foundation Ltd [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Research and development expense							3,400,000	$ 3,465,000	33,000	58,000
Selling, general and administrative expense								7,000	$ 185,000	$ 0
Private Placement [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Gross proceeds from issuance of shares	$ 13,500,000
Share price | $ / shares	$ 0.15
Series C Preferred Stock [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Issuance of Common Stock								18,427,000
Proceeds from issuance of preferred stock							$ 16,800,000	$ 18,427,000
2013 Plan [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Share issued upon exercise of stock option | shares								16,669
Eloxx Limited [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Reverse stock split	0.05
Issuance of shares in exchange of all outstanding capital stock | shares	20,316,656
Common stock, par value | $ / shares	$ 0.01
Warrants issued to purchase common stock to certain warrant holders | shares	346,307
Eloxx Limited [Member] | 2013 Plan [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Share issued upon exercise of stock option | shares	2,307,738
Shares reserved for future grants | shares	189,751

Significant Accounting Policies

Significant Accounting Policies - Summary of Useful Lives of Principal Classes of Assets (Detail)	12 Months Ended
	Dec. 31, 2017
Computers and software [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of asset	3 years
Office furniture and equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of asset	5 years
Office furniture and equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of asset	12 years
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of asset	5 years
Leasehold improvement [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life of asset, description	Over the shorter of the expected lease term or estimated useful life

Summary of Significant Accoun39

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Line Items]
Impairment losses	$ 0
Liability for unrecognized tax benefits	0	$ 0
Interest or penalties related to uncertain tax positions	0	0
Dividends	0
Payment of dividends	$ 0
Eloxx Limited [Member]
Accounting Policies [Line Items]
Percentage of monthly contribution for severance compensation expenses	8.33%
Severance compensation expenses	$ 64,000	$ 44,000	$ 35,000

Reverse Merger - Estimated Fair

Reverse Merger - Estimated Fair Values of the Assets Acquired and Liabilities Assumed (Detail) - Eloxx Limited [Member] $ in Thousands	Dec. 19, 2017USD ($)
Acquisition Date [Line Items]
Cash and cash equivalents	$ 123
Prepaid expenses and other current assets	220
Property, plant and equipment, net	39
Restricted bank deposits	6
Total assets acquired	388
Accounts payable	(215)
Accrued expenses	(343)
Total liabilities acquired	(558)
Total net liabilities acquired	$ (170)

Reverse Merger - Estimated Fa41

Reverse Merger - Estimated Fair Values of the Assets Acquired and Liabilities Assumed - Additional Information (Detail) $ in Millions	Dec. 19, 2017USD ($)
Eloxx Limited [Member]
Acquisition Date [Line Items]
Professional fees	$ 1.3

Prepaids and other current as42

Prepaids and other current assets - Schedule of Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Government grants from IIA		$ 605
Other governmental agencies	$ 88	221
Prepaid expenses	267	11
Total	$ 355	$ 837

Property and Equipment, net - P

Property and Equipment, net - Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Cost	$ 332	$ 56
Accumulated depreciation	54	15
Property and equipment, net	278	41
Computers and software [Member]
Property, Plant and Equipment [Line Items]
Cost	124	54
Office furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	118	$ 2
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	37
Leasehold improvement [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 53

Property and Equipment, net - A

Property and Equipment, net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation expenses	$ 39	$ 8	$ 5

Accrued Expenses - Accrued Expe

Accrued Expenses - Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued payroll and related expenses	$ 402	$ 393
Accrued research and development expenses	704	119
Accrued professional services	787	107
Total	$ 1,893	$ 619

Convertible Loan - Additional I

Convertible Loan - Additional Information (Detail) - Convertible Notes Payable [Member] $ in Thousands	Jan. 26, 2017USD ($)Lenders	May 31, 2017shares	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Debt Conversion [Line Items]
Debt Instrument, Periodic Payment, Interest			$ 700
Series C Preferred Stock [Member]
Debt Conversion [Line Items]
Stock Issued During Period, Shares, Conversion of Convertible Securities | shares		825,213
Convertible loan agreement [Member]
Debt Conversion [Line Items]
Debt instrument, convertible, latest date	2 years
Qualified equity investment, convertible threshold percentage of stock price trigger	80.00%
Debt Instrument, convertible, threshold percentage of stock price trigger	65.00%
Debt instrument, convertible, terms of conversion feature			According to the Agreement, the outstanding portion of the Convertible Loan (without accrued interest) should be automatically converted upon the consummation of equity investment by a third party of an aggregate amount of at least $5.0 million (the “Qualified Equity Investment”), prior to the lapse of two years from the Closing Date (the “Maturity Date”), into equity securities of the same class issued by the Company in such Qualified Equity Investment, in a conversion price which was equal to 80% of the price per share paid by the third party in such Qualified Equity Investment (the “Automatic Conversion”). In addition, upon the earlier of (i) Maturity Date or (ii) Event of Default as defined in the Agreement, the outstanding portion of the Convertible Loan (including accrued interest) should be converted into an equity investment of the then existing most senior class, at a conversion price per share which was equal to 65% of the original issue price per share applicable to such class. At the end of May 2017, the Lenders signed a waiver agreement pursuant to which they waived the potential discount as described above.
Convertible loan agreement [Member] | Lenders [Member]
Debt Conversion [Line Items]
Number of shareholder as lenders | Lenders	5
Debt Instrument, interest rate, stated percentage	5.00%
Debt Instrument, face amount	$ 2,500
Convertible loan agreement [Member] | Minimum [Member]
Debt Conversion [Line Items]
Qualified equity investment	5,000
Financial and Other Expense [Member]
Debt Conversion [Line Items]
Financial and other expenses, net, as a result of changes in the embedded instruments			$ 700
Fair Value, Inputs, Level 3 [Member]
Debt Conversion [Line Items]
Fair value assigned to the embedded conversion feature on the issuance dates	$ 300			$ 308

Convertible Loan - Reconciliati

Convertible Loan - Reconciliations for the Company's Liabilities Measured and Recorded at Fair Value on a Recurring Basis (Detail) - Fair Value, Inputs, Level 3 [Member] - Convertible Notes Payable [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Debt Conversion [Line Items]
Beginning Balance	$ (308)
Amortization and revaluation embedded conversion feature	(317)
Series C Preferred Stock [Member]
Debt Conversion [Line Items]
Conversion of convertible loan into Series C preferred stock	$ 625

Related Parties - Additional In

Related Parties - Additional Information (Detail) - USD ($)	Aug. 29, 2013	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Related Party Transaction Details [Line Items]
Research and development expense		$ 8,400,000	$ 16,398,000	$ 8,986,000	$ 5,842,000
General and administrative expenses		2,200,000	3,992,000	854,000	442,000
Accrued expenses		1,893,000	1,893,000	619,000
Technion Research and Development Foundation Ltd [Member]
Schedule Of Related Party Transaction Details [Line Items]
Research and development expense	$ 100,000		3,400,000
Aggregate milestone payment			$ 6,100,000
Collaborative arrangement additional consideration receivable as percentage of all non-refundable, non-contingent consideration			3.00%
Collaborative arrangement additional consideration receivable as percentage of non-refundable, non-contingent consideration received			3.00%
Technion Research and Development Foundation Ltd [Member] | Technion Agreement [Member]
Schedule Of Related Party Transaction Details [Line Items]
Research and development expense		3,400,000	$ 3,465,000	33,000	58,000
General and administrative expenses			7,000	185,000	$ 0
Accrued expenses		$ 25,000	$ 25,000	$ 185,000
Shares issued			2.10%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Dec. 18, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Lease expense		$ 200,000	$ 100,000	$ 100,000
Rehovot [Member] | Operating Lease Agreement To Lease Office Space [Member]
Lease agreement term		3 years
Lease period expiry date		Apr. 30, 2020
Extension of lease period		2 years
Annual lease payments		$ 100,000
Rehovot [Member] | Operating Lease Agreement to Lease Laboratory Space [Member]
Lease agreement term		1 year
Lease period expiry date		Mar. 8, 2018
Extension of lease period		1 year
Annual lease payments		$ 48,000
Waltham [Member] | Operating Lease Agreement To Lease Office Space [Member]
Lease agreement term		37 months
Lease period expiry date		Dec. 17, 2020
Extension of lease period		3 years
Annual lease payments		$ 200,000
Research and Development Agreements [Member]
Royalty payment as percentage of net sales		3.00%
Repayment percentage of grants received		100.00%
R&D grants received		$ 900,000	$ 1,200,000	$ 300,000
Royalty received		$ 2,700,000
Scripps Research Institute License Agreement [Member]
Royalty payment as percentage of net sales	2.00%	2.00%

Commitments and Contingencies50

Commitments and Contingencies - Schedule of Future Minimum Lease Payments (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,018	$ 258
2,019	232
2,020	186
Total	$ 676

Stockholder's Equity - Addition

Stockholder's Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	May 22, 2017	Sep. 30, 2016	Aug. 31, 2016	Feb. 29, 2016	Jul. 31, 2015	Apr. 30, 2015	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Preferred stock, shares issued							0	0	7,638,263
Preferred Stock, par value							$ 0.01	$ 0.01	$ 0.01
Number of common stock in warrant							480,049	480,049
Options exercised to purchase of common stock					99,829
Option exercise price per share					$ 0.01
Total consideration									$ 350
Common stock, shares issued							27,527,738	27,527,738	4,205,278
Common stock, par value							$ 0.01	$ 0.01	$ 0.01
Proceeds from issuance of common stock								$ 17,006
Warrant outstanding							480,049	480,049
Sevion Therapeutics Inc [Member]
Equity method investments							$ 1,500	$ 1,500
2017 Share Purchase Agreement [Member] | After Merger [Member]
Stock issuance costs								$ 500
Common stock, shares issued							6,333,333	6,333,333
Common stock, par value							$ 0.01	$ 0.01
Proceeds from issuance of common stock								$ 17,500
Series A Preferred Stock [Member]
Issuance of preferred stock										$ 860
Exercise price of warrants per share			$ 0.80
Series A Preferred Stock [Member] | TIOF [Member]
Warrant exercised			124,786
Series A Preferred Stock [Member] | TRDF [Member]
Warrant exercised			311,964
Series A Preferred Stock [Member] | TIOF and TRDF [Member]
Total consideration			$ 400
Series A Preferred Stock [Member] | 2013 Share Purchase Agreement [Member]
Preferred stock, shares issued						1,073,157
Preferred Stock, par value						$ 0.01
Issuance of preferred stock						$ 900
Series B 1 Preferred Stock [Member] | 2015 Share Purchase Agreement [Member]
Preferred stock, shares issued					1,002,049
Preferred Stock, par value					$ 0.01
Number of common stock in warrant					1,503,068
Exercise price of warrants per share					$ 3.11
Gross amount of warrants					$ 3,100
Warrant granted					1,503,068
Series B 1 Preferred Stock [Member] | 2015 Share Purchase Agreement [Member] | Share Based Contractor Compensation [Member]
Number of common stock in warrant					30,563
Exercise price of warrants per share					$ 3.11
Warrant granted					30,563
Payment to contractor					$ 100
Series B 1 Preferred Stock [Member] | 2016 Share Purchase Agreement [Member]
Preferred stock, shares issued				1,929,676
Preferred Stock, par value				$ 0.01
Number of common stock in warrant				2,894,519
Exercise price of warrants per share				$ 3.11
Warrant granted				2,894,519
Payment to contractor				$ 200
Gross amount of warrants				$ 6,000
Series B 1 Preferred Stock [Member] | 2016 Share Purchase Agreement [Member] | Share Based Contractor Compensation [Member]
Number of common stock in warrant				48,242
Exercise price of warrants per share				$ 3.11
Warrant granted				48,242
Series B 1 Preferred Stock [Member] | 2014 Share Purchase Agreement [Member]
Preferred stock, shares issued		1,174,138
Preferred Stock, par value		$ 0.01
Issuance of preferred stock		$ 3,700
Number of common stock in warrant		587,072
Warrant granted		587,072
Payment to contractor		$ 100
Milestone payment paid		$ 100
Series B 1 Preferred Stock [Member] | 2014 Share Purchase Agreement [Member] | Share Based Contractor Compensation [Member]
Number of common stock in warrant		36,593
Exercise price of warrants per share		$ 3.11
Warrant granted		36,593
Series C Preferred Stock [Member]
Issuance of preferred stock							$ 16,800	$ 18,427
Series C Preferred Stock [Member] | 2017 Share Purchase Agreement [Member]
Preferred stock, shares issued	7,136,289
Preferred Stock, par value	$ 0.01
Issuance of preferred stock	$ 21,500
Stock issuance costs	$ 600
Series C Preferred Stock [Member] | 2017 Share Purchase Agreement [Member] | Share Based Contractor Compensation [Member]
Number of common stock in warrant							142,524	142,524
Warrant granted								142,524
Series C Preferred Stock [Member] | 2017 Share Purchase Agreement [Member] | Sevion Therapeutics Inc [Member]
Shares issued as a result of the anti-dilution effect of the Reverse Merger	39,293

Stockholder's Equity - Summary

Stockholder's Equity - Summary of Warrants Outstanding (Detail)	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Class of Warrant or Right [Line Items]
Amount of outstanding warrants	480,049
Warrants One [Member]
Class of Warrant or Right [Line Items]
Amount of outstanding warrants	64,374
Weighted average exercise price | $ / shares	$ 0.800
Outstanding warrant expiration date	Dec. 19, 2022
Warrants Two [Member]
Class of Warrant or Right [Line Items]
Amount of outstanding warrants	59,415
Weighted average exercise price | $ / shares	$ 3.030
Outstanding warrant expiration date	Dec. 19, 2022
Warrants Three [Member]
Class of Warrant or Right [Line Items]
Amount of outstanding warrants	60,832
Weighted average exercise price | $ / shares	$ 3
Outstanding warrant expiration date	Dec. 19, 2022
Warrants Four [Member]
Class of Warrant or Right [Line Items]
Amount of outstanding warrants	22,282
Weighted average exercise price | $ / shares	$ 3.029
Outstanding warrant expiration date	Dec. 19, 2022
Warrants Five [Member]
Class of Warrant or Right [Line Items]
Amount of outstanding warrants	151,984
Weighted average exercise price | $ / shares	$ 3.109
Outstanding warrant expiration date	Dec. 19, 2022
Warrants Six [Member]
Class of Warrant or Right [Line Items]
Amount of outstanding warrants	48,252
Weighted average exercise price | $ / shares	$ 4.664
Outstanding warrant expiration date	Dec. 19, 2022
Warrants Seven [Member]
Class of Warrant or Right [Line Items]
Amount of outstanding warrants	68,434
Weighted average exercise price | $ / shares	$ 8
Outstanding warrant expiration date	Jan. 27, 2018
Warrants Eight [Member]
Class of Warrant or Right [Line Items]
Amount of outstanding warrants	4,474
Weighted average exercise price | $ / shares	$ 40
Outstanding warrant expiration date	May 16, 2019
Warrants Nine [Member]
Class of Warrant or Right [Line Items]
Amount of outstanding warrants	2
Weighted average exercise price | $ / shares	$ 520
Outstanding warrant expiration date	Nov. 17, 2020

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)CompensationPlan$ / sharesshares	Dec. 31, 2016$ / shares	Dec. 31, 2015$ / shares	Dec. 31, 2008shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity compensation plans | CompensationPlan	2
Weighted average grant date fair value of options granted | $ / shares	$ 3.68	$ 0.14	$ 0.17
2013 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance	2,473,255
Common Stock available for future grant	119,762
Unrecognized compensation cost related to non-vested stock options | $	$ 2.1
Unrecognized compensation cost expected to be recognized over a weighted-average period	2 years 1 month 2 days
Excercise price per share | $ / shares	$ 5.40
2013 Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted become fully exercisable	2 years
2013 Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted become fully exercisable	4 years
Share option expiration period	10 years
2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance				245,884
Rate increase on share reserve	5.00%
Maximum increase on share reserve	75,000
Maximum aggregate rate increase on share reserve	25.00%
Additional shares increased	126,051
Common Stock available for future grant	116,466
Chief Executive Officer [Member] | Performance Option Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase common stock granted	22,427
Excercise price per share | $ / shares	$ 8
Restricted stock unit	22,427
Chief Executive Officer [Member] | Time Vesting Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase common stock granted	640,785
Excercise price per share | $ / shares	$ 8
Restricted stock unit	640,785
Option vesting description	Subject to continued service through the vesting date, 1/3 of the Time-Vesting Awards will vest and become immediately exercisable on the first anniversary of the effective date, with an additional 1/12 of the Time-Vesting Awards vesting on each quarterly anniversary of the effective date

Stock-based Compensation - Tran

Stock-based Compensation - Transactions Related to Grant of Options to Employees and Directors (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Jul. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Amount
Exercised	(99,829)
Weighted average exercise price
Exercised	$ 0.01
2008 Plan [Member]
Amount
Options outstanding at beginning of year		215,723
Options outstanding at end of year		215,723	215,723
Options exercisable at end of year		215,723
Weighted average exercise price
Options outstanding at beginning of year		$ 28.93
Options outstanding at end of year		28.93	$ 28.93
Options exercisable at end of year		$ 28.93
Weighted average remaining contractual life
Options outstanding		7 years 9 months 18 days	7 years 9 months 18 days
Options exercisable at end of year		7 years 9 months 18 days
Aggregate intrinsic value
Options outstanding at beginning of year		$ 61,358
Options outstanding at end of year		338,056	$ 61,358
Options exercisable at end of year		$ 338,056
2013 Plan [Member]
Amount
Options outstanding at beginning of year		1,948,154
Granted		582,961
Exercised		(16,669)
Forfeited		(177,720)
Options outstanding at end of year		2,336,726	1,948,154
Options exercisable at end of year		1,624,407
Weighted average exercise price
Options outstanding at beginning of year		$ 0.47
Granted		5.40
Exercised		0.96
Forfeited		0.98
Options outstanding at end of year		1.82	$ 0.47
Options exercisable at end of year		$ 0.36
Weighted average remaining contractual life
Options outstanding		7 years 1 month 13 days	7 years 11 months 4 days
Options exercisable at end of year		6 years 15 days
Aggregate intrinsic value
Options outstanding at beginning of year		$ 1,571,406
Options outstanding at end of year		14,835,970	$ 1,571,406
Options exercisable at end of year		$ 12,408,281

Stock-based Compensation - Assu

Stock-based Compensation - Assumptions Used to Estimate Fair Values of Options Granted (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Dividend yield	0.00%	0.00%	0.00%
Volatility, minimum	87.17%	64.46%	73.70%
Volatility, maximum	116.69%	105.57%	88.72%
Risk free interest, minimum	1.22%	0.47%	0.25%
Risk free interest, maximum	2.50%	2.35%	1.87%
Contractual term (years)	10 years	10 years	10 years
Forfeiture rate post-vesting	10.00%	10.00%	10.00%
Suboptimal exercise	$ 2.3	$ 2.3	$ 2.3

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Allocated Stock-based Compensation Expense (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses		$ 101	$ 78	$ 92
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses		39	61	68
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses	[1]	$ 62	$ 17	$ 24
[1]	Including expenses of $19,000 in connection with restricted shares that were granted during the year ended December 31, 2017.

Stock-based Compensation - Su57

Stock-based Compensation - Summary of Allocated Stock-based Compensation Expense (Parenthetical) (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses		$ 101	$ 78	$ 92
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses	[1]	62	$ 17	$ 24
Restricted Stock [Member] | General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expenses		$ 19
[1]	Including expenses of $19,000 in connection with restricted shares that were granted during the year ended December 31, 2017.

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	Dec. 22, 2017	Dec. 19, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income tax examination, description				The Company is subject to income taxes in the United States and Israel. In general, the U.S. federal and state income tax returns remain open to examination by taxing authorities for tax years beginning in June 30, 2014 to present. The Israeli income tax returns remain open to examination beginning in 2013 to present. However, if and when the Company claims net operating loss (“NOL”) carryforwards from any prior years against future taxable income, those losses may be examined by the taxing authorities.
U.S. federal corporate income tax rate				34.00%
Deferred tax expense				$ 10,200,000
Undistributed earnings of foreign subsidiaries				0
Provision for deferred taxes				0
Valuation allowance				28,143,000	$ 4,023,000
Net deferred tax asset				0	$ 0
Change in valuation allowance				24,100,000
Valuation allowance deferred tax asset change in amount attributable to business combination		$ 30,200,000
Valuation allowance deferred tax asset change in amount attributable to change in federal tax rate	$ (10,200,000)
Increase in valuation allowance related to losses generated in current period				4,100,000
Federal research tax credit carryforwards		700,000		700,000
Federal [Member]
Net operating loss carryforwards		$ 77,100,000		77,200,000
State [Member]
Net operating loss carryforwards				27,400,000
Israel Tax Authority [Member]
Net operating loss carryforwards				$ 24,900,000
Earliest Tax Year [Member]
Federal research tax credit expiry, beginning period				2,027
Earliest Tax Year [Member] | Federal [Member]
U.S. net operating loss expiry, beginning period				2,019
Latest Tax Year [Member]
Federal research tax credit expiry, beginning period				2,037
Latest Tax Year [Member] | Federal [Member]
U.S. net operating loss expiry, beginning period				2,037
Scenario, Plan [Member]
U.S. federal corporate income tax rate			21.00%

Income Taxes - Deferred Income

Income Taxes - Deferred Income Tax Asset (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets
Net operation loss carryforward	$ 23,689	$ 2,811
Stock-based compensation	1,125
Reserves and allowances	11	17
U.S. tax credits and other	714
Research and development	2,604	1,195
Net deferred tax asset before valuation allowance	28,143	4,023
Valuation allowance	(28,143)	(4,023)
Net deferred tax asset	$ 0	$ 0

Income Taxes - Components of In

Income Taxes - Components of Income (Loss) Before Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S.	$ (21)	$ 44	$ 16
Israel	(21,145)	(9,883)	(6,418)
Income (loss) before taxes on income	$ (21,166)	$ (9,839)	$ (6,402)

Net Loss Per Share - Weighted A

Net Loss Per Share - Weighted Average Number of Shares Used in Computing Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
		Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Net loss		$ 10,600	$ 21,214	$ 9,847	$ 6,406
Dividends accumulated for the period	[1]		2,404	1,100	516
Net loss available to stockholders of Common Stock			$ 23,618	$ 10,947	$ 6,922
Denominator:
Shares used in computing net loss per share of Common Stock, basic and diluted			4,976,377	4,205,277	4,148,389
Net loss per share of Common Stock, basic and diluted			$ 4.75	$ 2.60	$ 1.67
[1]	The net loss used for the computation of basic and diluted net loss per share include 8% per share per annum compounded annually which was related to distributions for preferred stockholders of Eloxx Limited. On December 19, 2017 in conjunction with the Reverse Merger all preferred shares were converted to common shares.

Net Loss Per Share - Weighted62

Net Loss Per Share - Weighted Average Number of Shares Used in Computing Basic and Diluted Net Loss Per Share (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Percentage of dividend rate	8.00%

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Shares excluded from the calculation of the diluted net loss per share	19,027,306	12,746,823	6,778,980

Financial and Other Expenses,64

Financial and Other Expenses, net - Schedule of Financial and Other Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Income and Expenses [Abstract]
Exchange rate differences	$ 156	$ 7	$ 122
Amortization and revaluation of embedded conversion feature in respect to convertible loan	625
Interest expenses in respect to convertible loan	43
Total financial and other expense, net	$ 824	$ 7	$ 122

Segment and Geographic Inform65

Segment and Geographic Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017SegmentRegion
Segment Reporting [Abstract]
Number of operating segments | Segment	1
Number of geographic regions | Region	2

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - $ / shares	Dec. 26, 2017	Jan. 10, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Common stock, par value			$ 0.01	$ 0.01
2013 Plan [Member]
Subsequent Event [Line Items]
Common stock reserved for issuance			2,473,255
2013 Plan [Member] | Chief Executive Officer and Chairman [Member]
Subsequent Event [Line Items]
Options to purchase common stock granted	663,212
2013 Plan [Member] | Chief Executive Officer and Chairman [Member] | Restricted Stock Units [Member]
Subsequent Event [Line Items]
Restricted stock units	663,212
Subsequent Event [Member] | 2013 Plan [Member]
Subsequent Event [Line Items]
Common stock reserved for issuance		2,353,493
Common stock, par value		$ 0.01
Common Stock issuable upon exercise of stock options reserved for issuance		119,762