Allena Pharmaceuticals (ALNAQ) 10-Q 7 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 01, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	ALNA
Entity Registrant Name	ALLENA PHARMACEUTICALS, INC.
Entity Central Index Key	1,624,658
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		20,761,249

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 70,559	$ 94,494
Prepaid expenses and other current assets	2,178	1,539
Total current assets	72,737	96,033
Property and equipment, net	469	127
Other assets	191	89
Total assets	73,397	96,249
Current liabilities:
Accounts payable	1,779	1,724
Loan payable, net of discount		3,870
Accrued expenses and other current liabilities	3,159	1,949
Total current liabilities	4,938	7,543
Loan payable, net of current portion and discount	9,977	5,516
Other liabilities	37	320
Total liabilities	14,952	13,379
Commitments and contingencies (Note 9)
Stockholders’ equity:
Common stock, $0.001 par value; 125,000,000 shares authorized; 20,756,185 and 20,694,658 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively	21	20
Additional paid-in capital	166,418	164,807
Accumulated deficit	(107,994)	(81,957)
Total stockholders’ equity	58,445	82,870
Total liabilities and stockholders’ equity	$ 73,397	$ 96,249

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) (unaudited) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	20,756,185	20,694,658
Common stock, shares outstanding	20,756,185	20,694,658
Undesignated Preferred Stock
Convertible preferred stock, par value	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	5,000,000	0
Convertible preferred stock, shares issued	0	0
Convertible preferred stock, shares outstanding	0	0

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating expenses:
Research and development	$ 7,316	$ 2,949	$ 19,107	$ 10,758
General and administrative	2,389	1,413	6,706	3,621
Total operating expenses	9,705	4,362	25,813	14,379
Loss from operations	(9,705)	(4,362)	(25,813)	(14,379)
Other income (expense):
Interest income (expense), net	180	(146)	398	(401)
Other income (expense), net	15	(162)	(5)	(193)
Loss on extinguishment of debt			(617)
Other income (expense), net	195	(308)	(224)	(594)
Net loss	$ (9,510)	$ (4,670)	$ (26,037)	$ (14,973)
Net loss per share attributable to common stockholders—basic and diluted	$ (0.46)	$ (3.49)	$ (1.26)	$ (11.19)
Weighted-average common shares outstanding—basic and diluted	20,753,215	1,343,429	20,727,426	1,342,898
Net loss	$ (9,510)	$ (4,670)	$ (26,037)	$ (14,973)
Other comprehensive income (loss):
Unrealized gain on investments				2
Total other comprehensive income				2
Comprehensive loss	$ (9,510)	$ (4,670)	$ (26,037)	$ (14,971)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net loss	$ (26,037)	$ (14,973)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,512	295
Depreciation expense	44	53
Non-cash interest expense	159	264
Loss on extinguishment of debt	617
Amortization of premium on investments		33
Change in fair value of warrant liability		193
Changes in assets and liabilities:
Prepaid expenses and other current assets	(639)	(22)
Other assets	(102)	(89)
Accounts payable	(1)	150
Accrued expenses	1,300	(132)
Other liabilities	18
Net cash used in operating activities	(23,129)	(14,228)
Cash flows from investing activities:
Purchases of property and equipment	(156)	(56)
Purchases of investments		(1,247)
Maturities of investments		24,721
Net cash (used in) provided by investing activities	(156)	23,418
Cash flows from financing activities:
Proceeds from exercise of stock options	87	5
Payments of initial public offering costs	(186)	(571)
Proceeds from loan payable	10,000
Repayment of loan payable	(10,492)
Debt issuance costs paid	(33)
Capital lease payments	(26)
Net cash used in financing activities	(650)	(566)
Net (decrease) increase in cash and cash equivalents	(23,935)	8,624
Cash and cash equivalents, beginning of period	94,494	25,250
Cash and cash equivalents, end of period	$ 70,559	33,874
Supplemental disclosure of non-cash activities:
Accretion of convertible preferred stock to redemption value		$ 52

Nature of Business

Nature of Business	9 Months Ended
	Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Business	1. Nature of Business Allena Pharmaceuticals, Inc. (the “Company”) is a late-stage clinical biopharmaceutical company dedicated to developing and commercializing first-in-class, oral enzyme therapeutics to treat patients with rare and severe metabolic and kidney disorders. The Company is focused on metabolic disorders that result in excess accumulation of certain metabolites that can cause kidney stones, damage the kidney, and potentially lead to chronic kidney disease (“CKD”), and end-stage renal disease. The Company’s lead product candidate, reloxaliase (formerly known as ALLN-177), is a first-in-class, oral enzyme therapeutic that it is developing for the treatment of hyperoxaluria, a metabolic disorder commonly associated with kidney stones, CKD and other serious kidney diseases. The Company was incorporated under the laws of the State of Delaware on June 24, 2011 and is located in Newton, Massachusetts. The Company is subject to risks common to companies in the biotechnology industry, including but not limited to, risks of failure of preclinical studies and clinical trials, the need to obtain marketing approval for any drug product candidate that it may identify and develop, the need to successfully commercialize and gain market acceptance of its product candidates, dependence on key personnel, protection of proprietary technology, compliance with government regulations, development by competitors of technological innovations, reliance on third party manufacturers, ability to transition from pilot-scale manufacturing to large-scale production of products and the need to obtain adequate additional financing to fund the development of its product candidates. The Company has an accumulated deficit of $108.0 million at September 30, 2018, and will require substantial additional capital to fund operations. The future success of the Company is dependent on its ability to identify and develop its product candidates and ultimately upon its ability to attain profitable operations. At September 30, 2018, the Company had $70.6 million of cash and cash equivalents. The Company believes that its cash and cash equivalents as of September 30, 2018 will be sufficient to fund the Company’s operating plan into 2020.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The Company’s unaudited interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (ASU) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2017 and notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 filed with the SEC on March 27, 2018. The unaudited interim consolidated financial statements have been prepared on the same basis as the audited financial statements. In the opinion of the Company’s management, the accompanying unaudited interim condensed consolidated financial statements contain all adjustments which are necessary to present fairly the Company’s financial position as of September 30, 2018, the results of its operations for the three and nine months ended September 30, 2018 and 2017 and cash flows for the nine months ended September 30, 2018 and 2017. Such adjustments are of a normal and recurring nature. The results for the three and nine months ended September 30, 2018 are not necessarily indicative of the results for the year ending December 31, 2018, or for any future period. Principles of Consolidation The consolidated financial statements include the accounts of Allena Pharmaceuticals, Inc. and its wholly owned subsidiaries Allena Pharmaceuticals Security Corporation (“Security Corporation”), which was incorporated in December 2014, and Allena Pharmaceuticals Ireland Limited, which was incorporated in March 2017. All intercompany transactions and balances have been eliminated. Fair Value of Financial Instruments Fair value is defined as the price that would be received upon sale of an asset or paid to transfer a liability between market participants at measurement dates. ASC Topic 820, Fair Value Measurement Level 1 inputs: Quoted prices in active markets for identical assets or liabilities. Level 2 inputs: Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves. Level 3 inputs: Unobservable inputs developed using estimates or assumptions developed by the Company, which reflect those that a market participant would use in pricing the asset or liability. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The remainder of the Company’s significant accounting policies are described in the Annual Report filed on Form 10-K for the year ended December 31, 2017 that was filed with the United States Securities and Exchange Commission on March 27, 2018. Recently Adopted Accounting Pronouncements In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments In May 2017, the FASB issued ASU No. 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) In June 2018, the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting In 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Net Loss per Share	3. Net Loss per Share Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. The Company has computed diluted net loss per common share after giving consideration to all potentially dilutive common shares, including options to purchase common stock, restricted common stock, convertible preferred stock and warrants to purchase convertible preferred stock (that were converted into warrants to purchase common stock in connection with the Company’s IPO in November 2017), outstanding during the period determined using the treasury-stock and if-converted methods, except where the effect of including such securities would be antidilutive. Because the Company has reported net losses since inception, these potential common shares have been anti-dilutive and basic and diluted loss per share have been the same. Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Numerator: Net loss $ (9,510 ) $ (4,670 ) $ (26,037 ) $ (14,973 ) Accretion of convertible preferred stock — (17 ) — (52 ) Net loss attributable to common stockholders $ (9,510 ) $ (4,687 ) $ (26,037 ) $ (15,025 ) Denominator: Weighted-average common shares—basic and diluted 20,753,215 1,343,429 20,727,426 1,342,898 Net loss per share attributable to common stockholders—basic and diluted $ (0.46 ) $ (3.49 ) $ (1.26 ) $ (11.19 ) The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because to include them would be anti-dilutive (in common stock equivalent shares): Nine Months Ended September 30, 2018 2017 Series A convertible preferred stock — 4,400,410 Series B convertible preferred stock — 4,753,536 Series C convertible preferred stock — 4,791,563 Warrants 9,040 43,265 Stock options 2,134,904 1,528,370 Total 2,143,944 15,517,144

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The following tables present information about the Company’s financial assets and liabilities that have been measured at fair value at September 30, 2018 and December 31, 2017, and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands): Description September 30, 2018 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 63,782 $ 63,782 $ — $ — Total assets $ 63,782 $ 63,782 $ — $ — Description December 31, 2017 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 93,745 $ 93,745 $ — $ — Total assets $ 93,745 $ 93,745 $ — $ — At September 30, 2018 and December 31, 2017, all of the Company’s cash equivalents were comprised of money market funds. There were no changes to the valuation methods during the three and nine months ended September 30, 2018 and the year ended December 31, 2017. There were no transfers within the fair value hierarchy during the three and nine months ended September 30, 2018 and the year ended December 31, 2017. The carrying amounts reflected in the consolidated balance sheets for cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their carrying values. The Company believes the terms of the loan payable reflect current market conditions for an instrument with similar terms and maturity, therefore the carrying value of the Company’s debt approximates its fair value based on Level 3 of the fair value hierarchy.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2018
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	5. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consist of the following (in thousands): September 30, 2018 December 31, 2017 Payroll and employee-related expenses $ 1,422 $ 1,132 Professional fees 237 420 Third-party research and development expenses 1,400 135 IPO-related services — 111 Other 100 151 Total accrued expenses and other current liabilities $ 3,159 $ 1,949

Loan and Security Agreement

Loan and Security Agreement	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Loan and Security Agreement	6. Loan and Security Agreement In August 2014, the Company entered into a Loan Agreement with Silicon Valley Bank (“SVB”) and borrowed $7.0 million under the loan. In May 2016, the Loan Agreement was amended (“Amended Loan Agreement”) to borrow up to $10.0 million with a portion of the proceeds to be used to pay down the outstanding balance of the original $7.0 million of advances. At the time of the Amended Loan Agreement, SVB advanced a gross amount of $7.5 million to the Company. Net proceeds received by the Company were $1.6 million after deducting $5.3 million for repayment of the original advances and $0.6 million for final interest due upon maturity or prepayment of the original advances. In December 2016, upon the achievement of certain milestones, SVB advanced the remaining $2.5 million available under the Amended Loan Agreement. The borrowings were secured by a lien on all Company assets, excluding intellectual property. The May 2016 and December 2016 advances had a floating per annum interest rate of the greater of 4.0% or 0.5% above the prime rate. In December 2016, the interest only period was extended to 18 months. Upon the expiration of the interest only period, amounts borrowed were to be repaid over 30 equal monthly payments of principal and interest. At its option, the Company could prepay all, but not less than all, of the outstanding borrowings subject to a prepayment premium as defined in the Amended Loan Agreement. The Company was also required to make a final payment equal to 8.25% of the total borrowings (“Final Payment”) on the earliest of the loan maturity date, an acceleration of the loan as defined in the Amended Loan Agreement or at the time of prepayment. On June 29, 2018, the Company terminated the Amended Loan Agreement and repaid the $7.7 million outstanding principal balance and the Final Payment to SVB. The Company recorded a loss on extinguishment of debt of $0.6 million in the Statement of Operations, accordingly. On June 29, 2018 the Company also entered into a loan agreement with Pacific Western Bank (“PWB Loan Agreement”) providing up to $12.0 million of borrowings, of which $10.0 million was advanced on June 29, 2018. The remaining $2.0 million of borrowings available under the PWB Loan Agreement are available to the Company through one additional advance request until the end of the interest only period as defined below. Borrowings are secured by a lien on all Company assets, excluding intellectual property, and amounts borrowed have a floating per annum interest rate of the greater of 5.0% or the prime rate. The PWB Loan Agreement has a term of 48 months and an initial interest only period of 18 months. If the Company receives at least $50M of gross proceeds from the sale of its equity securities or upfront cash payment from a strategic partnership prior the expiration of the initial interest only period, the interest only period will be extended an additional six months. Upon the expiration of the initial interest only period on December 31, 2019, amounts borrowed will be repaid over 30 equal monthly payments of principal plus accrued but unpaid interest. If the interest only period is extended an additional six months, amounts borrowed will be repaid over 24 equal monthly payments of principal plus accrued but unpaid interest beginning July 1, 2020. At its option, the Company may prepay all, but not less than all, of the outstanding borrowings subject to a prepayment premium as defined in the Loan Agreement. Upon the closing of one or more financings, in which the Company receives aggregate gross proceeds of at least $25 million, a success fee will be paid to the Lender. If the gross proceeds are received on or before June 30, 2019, the Success Fee is $200,000, and f the gross proceeds are received after June 30, 2019, the Success Fee is $300,000. The Company’s obligation to pay this Success Fee survives termination of the Agreement. The PWB Loan Agreement contains negative covenants restricting the Company’s activities, including limitations on dispositions, mergers or acquisitions, incurring indebtedness or liens, paying dividends or making investments and certain other business transactions. There are no financial covenants associated with the PWB Loan Agreement. The obligations under the PWB Loan Agreement are subject to acceleration upon the occurrence of specified events of default, including a material adverse change in the Company’s business, operations or financial or other condition. The Company has determined that the risk of subjective acceleration under the material adverse events clause is remote and therefore has classified the outstanding principal based on scheduled principal payments. The Company evaluated the PWB Loan Agreement for embedded features that require bifurcation, noting certain features were required to be bifurcated, but were concluded to be de minimis in value at September 30, 2018.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Stockholders' Equity	7. Stockholders’ Equity Common Stock Common stockholders are not entitled to receive dividends, unless declared by the Board of Directors. At September 30, 2018, warrants to purchase up to 9,040 shares of common stock at an exercise price of $11.06 were outstanding. These warrants expire on May 1, 2026. The Company has reserved for future issuances the following shares of common stock as of September 30, 2018 and December 31, 2017: September 30, 2018 December 31, 2017 Warrants 9,040 9,040 Stock options 4,307,693 3,538,345 Employee stock purchase plan 413,230 206,284 Total 4,729,963 3,753,669

Stock Incentive Plan

Stock Incentive Plan	9 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Incentive Plan	8. Stock Incentive Plan On October 31, 2017, the Company adopted the 2017 Stock Option and Incentive Plan (“2017 Plan”). Upon the adoption of the 2017 Plan, no further grants would be made under the 2011 Stock Incentive Plan (“2011 Plan”). The 2017 Plan initially provided for the grant of awards for 2,038,021 shares of common stock. In addition to the shares available for grant under the 2017 Plan, any awards outstanding under the 2011 Plan as of the October 31, 2017 are cancelled, forfeited or otherwise terminated without being exercised, the number of shares underlying such awards will be available for future grant under the 2017 Plan. The 2017 Plan also provides that an additional number of shares will automatically be added to the shares authorized for issuance under the 2017 Plan on January 1 of each year. The number of shares added each year will be equal to the lesser of: (i) 4% of the outstanding shares on the immediately preceding December 31 or (ii) such amount as determined by the Compensation Committee of the registrant’s Board of Directors. On January 1, 2018, the shares available for grant under the 2017 Plan was automatically increased by 827,786 shares. All of the Company’s employees, officers, directors, consultants and advisors are eligible to be granted options, restricted stock units (“RSUs”), and other share-based awards under the terms of the 2017 Plan. As of September 30, 2018, 2,172,789 shares of common stock were available for future grant under the 2017 Plan. All stock option grants are nonstatutory stock options except option grants to employees (including officers and directors) intended to qualify as incentive stock options under the Internal Revenue Code of 1986, as amended. Incentive stock options may not be granted at less than the fair market value of the Company’s common stock on the date of grant, as determined in good faith by the Board of Directors at its sole discretion. Nonqualified stock options may be granted at an exercise price established by the Board of Directors at its sole discretion (which has not been less than fair market value on the date of grant) and the vesting periods may vary. Vesting periods are generally four years and are determined by the Board of Directors or a delegated subcommittee. Stock options become exercisable as they vest. Options granted under both the 2011 Plan and 2017 Plan expire no more than 10 years from the date of grant. Stock-based compensation expense included in the Company’s statements of operations and comprehensive loss is as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Research and development $ 157 $ 30 $ 391 $ 87 General and administrative 438 69 1,121 208 Total $ 595 $ 99 $ 1,512 $ 295 The fair value of each stock option granted to employees and directors was estimated on the date of grant using the Black-Scholes option-pricing model, with the following range of assumptions as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Risk-free interest rate 2.8% 1.9%-2.0% 2.3%-2.8% 1.9%-2.0% Expected dividend yield —% —% —% —% Expected term (in years) 5.6-6.1 5.9-6.3 5.5-6.1 5.6-6.3 Expected volatility 84%-85% 82% 81%-89% 82%-87% A summary of the stock option activity under the 2011 and 2017 Plans is as follows: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2017 1,508,124 1.89 7.9 $ 12,328 Granted 743,674 8.50 Exercised (61,527 ) 1.42 Cancelled (55,367 ) 5.69 Outstanding at September 30, 2018 2,134,904 $ 4.11 7.9 $ 14,554 Exercisable at September 30, 2018 1,101,412 $ 1.91 7.0 $ 9,721 As of September 30, 2018, total unrecognized stock-based compensation expense relating to unvested stock options was $4.6 million. This amount is expected to be recognized over a weighted-average period of 2.9 years.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies The Company has operating leases for office space in Newton, MA (“Newton Lease”) and for laboratory space in Sudbury, MA (“Sudbury Lease”). The Newton lease expires in December 2020 and base rent is $0.3 million annually. In March 2018, the Company amended the Sudbury Lease to reduce the square footage and to extend the term to February 28, 2021. In August 2018, the Company amended the amended Sudbury Lease, adding approximately 2,928 square feet of office space. Base rent for the Sudbury Lease is approximately $0.2 million annually.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s unaudited interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (ASU) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2017 and notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 filed with the SEC on March 27, 2018. The unaudited interim consolidated financial statements have been prepared on the same basis as the audited financial statements. In the opinion of the Company’s management, the accompanying unaudited interim condensed consolidated financial statements contain all adjustments which are necessary to present fairly the Company’s financial position as of September 30, 2018, the results of its operations for the three and nine months ended September 30, 2018 and 2017 and cash flows for the nine months ended September 30, 2018 and 2017. Such adjustments are of a normal and recurring nature. The results for the three and nine months ended September 30, 2018 are not necessarily indicative of the results for the year ending December 31, 2018, or for any future period.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of Allena Pharmaceuticals, Inc. and its wholly owned subsidiaries Allena Pharmaceuticals Security Corporation (“Security Corporation”), which was incorporated in December 2014, and Allena Pharmaceuticals Ireland Limited, which was incorporated in March 2017. All intercompany transactions and balances have been eliminated.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the price that would be received upon sale of an asset or paid to transfer a liability between market participants at measurement dates. ASC Topic 820, Fair Value Measurement Level 1 inputs: Quoted prices in active markets for identical assets or liabilities. Level 2 inputs: Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves. Level 3 inputs: Unobservable inputs developed using estimates or assumptions developed by the Company, which reflect those that a market participant would use in pricing the asset or liability. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The remainder of the Company’s significant accounting policies are described in the Annual Report filed on Form 10-K for the year ended December 31, 2017 that was filed with the United States Securities and Exchange Commission on March 27, 2018.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments In May 2017, the FASB issued ASU No. 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606)
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) In June 2018, the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting In 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Summary of Basic and Diluted Net Loss per Share Attributable to Common Stockholders	Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Numerator: Net loss $ (9,510 ) $ (4,670 ) $ (26,037 ) $ (14,973 ) Accretion of convertible preferred stock — (17 ) — (52 ) Net loss attributable to common stockholders $ (9,510 ) $ (4,687 ) $ (26,037 ) $ (15,025 ) Denominator: Weighted-average common shares—basic and diluted 20,753,215 1,343,429 20,727,426 1,342,898 Net loss per share attributable to common stockholders—basic and diluted $ (0.46 ) $ (3.49 ) $ (1.26 ) $ (11.19 )
Summary of Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss per Share	The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because to include them would be anti-dilutive (in common stock equivalent shares): Nine Months Ended September 30, 2018 2017 Series A convertible preferred stock — 4,400,410 Series B convertible preferred stock — 4,753,536 Series C convertible preferred stock — 4,791,563 Warrants 9,040 43,265 Stock options 2,134,904 1,528,370 Total 2,143,944 15,517,144

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Summary of Financial Assets and Liabilities Measured at Fair Value	The following tables present information about the Company’s financial assets and liabilities that have been measured at fair value at September 30, 2018 and December 31, 2017, and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands): Description September 30, 2018 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 63,782 $ 63,782 $ — $ — Total assets $ 63,782 $ 63,782 $ — $ — Description December 31, 2017 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 93,745 $ 93,745 $ — $ — Total assets $ 93,745 $ 93,745 $ — $ —

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2018
Payables And Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following (in thousands): September 30, 2018 December 31, 2017 Payroll and employee-related expenses $ 1,422 $ 1,132 Professional fees 237 420 Third-party research and development expenses 1,400 135 IPO-related services — 111 Other 100 151 Total accrued expenses and other current liabilities $ 3,159 $ 1,949

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Summary of Shares of Common Stock Reserved	The Company has reserved for future issuances the following shares of common stock as of September 30, 2018 and December 31, 2017: September 30, 2018 December 31, 2017 Warrants 9,040 9,040 Stock options 4,307,693 3,538,345 Employee stock purchase plan 413,230 206,284 Total 4,729,963 3,753,669

Stock Incentive Plan (Tables)

Stock Incentive Plan (Tables)	9 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock-based Compensation Expense	Stock-based compensation expense included in the Company’s statements of operations and comprehensive loss is as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Research and development $ 157 $ 30 $ 391 $ 87 General and administrative 438 69 1,121 208 Total $ 595 $ 99 $ 1,512 $ 295
Schedule of Assumptions Used in Black-Scholes Option Pricing Model to Estimate Fair Value of Stock Options	The fair value of each stock option granted to employees and directors was estimated on the date of grant using the Black-Scholes option-pricing model, with the following range of assumptions as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Risk-free interest rate 2.8% 1.9%-2.0% 2.3%-2.8% 1.9%-2.0% Expected dividend yield —% —% —% —% Expected term (in years) 5.6-6.1 5.9-6.3 5.5-6.1 5.6-6.3 Expected volatility 84%-85% 82% 81%-89% 82%-87%
Summary of Stock Option Activity	A summary of the stock option activity under the 2011 and 2017 Plans is as follows: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2017 1,508,124 1.89 7.9 $ 12,328 Granted 743,674 8.50 Exercised (61,527 ) 1.42 Cancelled (55,367 ) 5.69 Outstanding at September 30, 2018 2,134,904 $ 4.11 7.9 $ 14,554 Exercisable at September 30, 2018 1,101,412 $ 1.91 7.0 $ 9,721

Nature of Business - Additional

Nature of Business - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accumulated deficit	$ 107,994	$ 81,957
Cash and cash equivalents	$ 70,559	$ 94,494

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018
Summary Of Significant Accounting Policies [Line Items]
Entity incorporated date	Dec. 31, 2014
Allena Pharmaceuticals Security Corporation
Summary Of Significant Accounting Policies [Line Items]
Entity incorporated date	Dec. 31, 2014
Allena Pharmaceuticals Ireland Limited
Summary Of Significant Accounting Policies [Line Items]
Entity incorporated date	Mar. 31, 2017

Net Loss per Share - Summary of

Net Loss per Share - Summary of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net loss	$ (9,510)	$ (4,670)	$ (26,037)	$ (14,973)
Accretion of convertible preferred stock		(17)		(52)
Net loss attributable to common stockholders	$ (9,510)	$ (4,687)	$ (26,037)	$ (15,025)
Denominator:
Weighted-average common shares—basic and diluted	20,753,215	1,343,429	20,727,426	1,342,898
Net loss per share attributable to common stockholders—basic and diluted	$ (0.46)	$ (3.49)	$ (1.26)	$ (11.19)

Net Loss per Share - Summary _2

Net Loss per Share - Summary of Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss per Share (Details) - shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of loss per share	2,143,944	15,517,144
Series A Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of loss per share		4,400,410
Series B Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of loss per share		4,753,536
Series C Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of loss per share		4,791,563
Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of loss per share	9,040	43,265
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of loss per share	2,134,904	1,528,370

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	$ 63,782	$ 93,745
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	63,782	93,745
Money market funds, included in cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value disclosure	63,782	93,745
Money market funds, included in cash and cash equivalents | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value disclosure	$ 63,782	$ 93,745

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Change in valuation methods or transfers	$ 0	$ 0	$ 0
Transfers within fair value hierarchy	$ 0	$ 0	$ 0

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Payroll and employee-related expenses	$ 1,422	$ 1,132
Professional fees	237	420
Third-party research and development expenses	1,400	135
IPO-related services		111
Other	100	151
Total accrued expenses and other current liabilities	$ 3,159	$ 1,949

Loan and Security Agreement - A

Loan and Security Agreement - Additional Information (Details)	Jun. 29, 2018USD ($)MonthlyPayment	Dec. 31, 2016USD ($)	May 31, 2016USD ($)	Sep. 30, 2018USD ($)MonthlyPayment	Aug. 31, 2014USD ($)
Debt Instrument [Line Items]
Loss on extinguishment of debt				$ 617,000
Loan Agreement | SVB
Debt Instrument [Line Items]
Loan agreement, maximum borrowing capacity			$ 10,000,000		$ 7,000,000
Proceeds from loan agreement		$ 2,500,000	7,500,000
Net proceeds from loan agreement			1,600,000
Repayment under loan agreement			5,300,000
Payment for final interest due upon maturity or prepayment of the original advances			$ 600,000
Loan agreement, stated interest rate			4.00%
Loan agreement, interest rate above prime rate			0.50%
Loan agreement, extended interest only payment period		18 months
Loan agreement, number of monthly payments | MonthlyPayment				30
Loan agreement, frequency of payments				monthly
Percentage of final payment based on total borrowings				8.25%
Repayment of outstanding principal balance	$ 7,700,000
Loss on extinguishment of debt	600,000
Loan Agreement | PWB
Debt Instrument [Line Items]
Loan agreement, maximum borrowing capacity	$ 12,000,000
Loan agreement, interest rate above prime rate	5.00%
Loan agreement, extended interest only payment period	18 months
Loan agreement, number of monthly payments | MonthlyPayment	30
Loan agreement, frequency of payments				monthly
Loan agreement, advanced amount	$ 10,000,000
Loan agreement, remaining borrowing capacity	$ 2,000,000
Loan agreement, term	48 months
Gross proceeds from sale of equity securities or upfront cash payment	$ 50,000,000
Loan agreement, extended additional interest only payment period	6 months
Expiration period	Dec. 31, 2019
Loan agreement, number of additional monthly payments | MonthlyPayment	24
Aggregate gross proceeds for success fee to be paid	$ 25,000,000
Success fee if gross proceeds received before June 30, 2019	200,000
Success fee if gross proceeds received after June 30, 2019	$ 300,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018$ / sharesshares
Stockholders' Equity Note [Abstract]
Warrants exercisable shares | shares	9,040
Exercise price of warrants | $ / shares	$ 11.06
Warrant expiration date	May 1, 2026

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Shares of Common Stock Reserved (Details) - shares	Sep. 30, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Shares of common stock reserved for future issuances	4,729,963	3,753,669
Warrants
Class of Stock [Line Items]
Shares of common stock reserved for future issuances	9,040	9,040
Stock Options
Class of Stock [Line Items]
Shares of common stock reserved for future issuances	4,307,693	3,538,345
Employee Stock Purchase Plan
Class of Stock [Line Items]
Shares of common stock reserved for future issuances	413,230	206,284

Stock Incentive Plan - Addition

Stock Incentive Plan - Additional Information (Details) - USD ($) $ in Millions	Jan. 01, 2018	Oct. 31, 2017	Sep. 30, 2018
2011 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for grant		0
2011 Plan | Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based award, vesting period			4 years
2011 Plan | Stock Options | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based award, expiration period			10 years
2017 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option grant effective date		Oct. 31, 2017
Share based award, description			Upon the adoption of the 2017 Plan, no further grants would be made under the 2011 Stock Incentive Plan (“2011 Plan”). The 2017 Plan initially provided for the grant of awards for 2,038,021 shares of common stock. In addition to the shares available for grant under the 2017 Plan, any awards outstanding under the 2011 Plan as of the October 31, 2017 are cancelled, forfeited or otherwise terminated without being exercised, the number of shares underlying such awards will be available for future grant under the 2017 Plan. The 2017 Plan also provides that an additional number of shares will automatically be added to the shares authorized for issuance under the 2017 Plan on January 1 of each year. The number of shares added each year will be equal to the lesser of: (i) 4% of the outstanding shares on the immediately preceding December 31 or (ii) such amount as determined by the Compensation Committee of the registrant’s Board of Directors. On January 1, 2018, the shares available for grant under the 2017 Plan was automatically increased by 827,786 shares.
Percentage criteria for additional shares granted		4.00%
Additional shares available for grant	827,786
2017 Plan | Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future grant			2,172,789
Stock-based award, vesting period			4 years
2017 Plan | Stock Options | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based award, expiration period			10 years
2017 Plan | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for grant		2,038,021
2011 And 2017 Plans
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense related to unvested employee stock options			$ 4.6
Unrecognized stock-based compensation expense, weighted average period for recognition			2 years 10 months 24 days

Stock Incentive Plan - Summary

Stock Incentive Plan - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 595	$ 99	$ 1,512	$ 295
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	157	30	391	87
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 438	$ 69	$ 1,121	$ 208

Stock Incentive Plan - Schedule

Stock Incentive Plan - Schedule of Assumptions Used in Black-Scholes Option Pricing Model to Estimate Fair Value of Stock Options (Details) - Stock Options - Employees and Directors	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	2.80%
Risk-free interest rate, minimum		1.90%	2.30%	1.90%
Risk-free interest rate, maximum		2.00%	2.80%	2.00%
Expected volatility		82.00%
Expected volatility, minimum	84.00%		81.00%	82.00%
Expected volatility, maximum	85.00%		89.00%	87.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 7 months 6 days	5 years 10 months 24 days	5 years 6 months	5 years 7 months 6 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days	6 years 3 months 18 days	6 years 1 month 6 days	6 years 3 months 18 days

Stock Incentive Plan - Summar_2

Stock Incentive Plan - Summary of Stock Option Activity (Details) - 2011 And 2017 Plans - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Outstanding, Beginning balance	1,508,124
Shares, Granted	743,674
Shares, Exercised	(61,527)
Shares, Cancelled	(55,367)
Shares, Outstanding, Ending balance	2,134,904	1,508,124
Shares, Exercisable	1,101,412
Weighted-Average Exercise Price, Outstanding, Beginning balance	$ 1.89
Weighted-Average Exercise Price, Granted	8.50
Weighted-Average Exercise Price, Exercised	1.42
Weighted-Average Exercise Price, Cancelled	5.69
Weighted-Average Exercise Price, Outstanding, Ending balance	4.11	$ 1.89
Weighted-Average Exercise Price, Exercisable	$ 1.91
Weighted-Average Remaining Contractual Life (in years), Outstanding	7 years 10 months 24 days	7 years 10 months 24 days
Weighted-Average Remaining Contractual Life (in years), Exercisable	7 years
Aggregate Intrinsic Value, Outstanding	$ 14,554	$ 12,328
Aggregate Intrinsic Value, Exercisable	$ 9,721

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	1 Months Ended		9 Months Ended
	Aug. 31, 2018USD ($)ft²	Mar. 31, 2018	Sep. 30, 2018USD ($)
Newton, MA
Operating Leased Assets [Line Items]
Base rent for office space			$ 0.3
Operating lease expiration period			2020-12
Sudbury, MA | Lease Amendment One
Operating Leased Assets [Line Items]
Operating lease extended expiration date		Feb. 28, 2021
Rentable office space under operating lease | ft²	2,928
Base rent for lab space	$ 0.2