Regulus Therapeutics (RGLS) 10-Q 10 Aug 21 2021 Q2 Quarterly report Financial data

Cover

Cover - shares	6 Months Ended
	Jun. 30, 2021	Aug. 06, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	001-35670
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-4738379
Entity Address, Address Line One	4224 Campus Point Court, Suite 210
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	202-6300
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	RGLS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		87,040,335
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Registrant Name	REGULUS THERAPEUTICS INC.
Entity Central Index Key	0001505512
Current Fiscal Year End Date	--12-31

CONDENSED BALANCE SHEETS

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 41,440	$ 31,087
Restricted cash	62	0
Contract and other receivables	194	503
Prepaid materials, net	3,269	3,314
Prepaid expenses and other current assets	1,348	1,826
Total current assets	46,313	36,730
Property and equipment, net	284	472
Intangibles, net	105	125
Right of use asset	2,814	253
Other assets	0	24
Total assets	49,516	37,604
Current liabilities:
Accounts payable	1,393	535
Accrued liabilities	477	581
Accrued research and development expenses	762	1,097
Accrued compensation	1,158	1,743
Current portion of term loan, less debt issuance costs	4,662	4,652
Other current liabilities	1,516	2,970
Total current liabilities	9,968	11,578
Lease liability, less current portion	2,720	0
Total liabilities	12,688	11,578
Commitments and Contingencies	0	0
Stockholders’ equity:
Common stock, $0.001 par value; 400,000,000 shares and 200,000,000 authorized at June 30, 2021 and December 31, 2020, respectively; 87,040,335 and 67,432,712 shares issued and outstanding at June 30, 2021 (unaudited) and December 31, 2020, respectively	87	67
Additional paid-in capital	475,831	453,002
Accumulated deficit	(439,092)	(427,045)
Total stockholders’ equity	36,828	26,026
Total liabilities and stockholders’ equity	49,516	37,604
Class A-1 Convertible Preferred Stock
Stockholders’ equity:
Preferred stock	0	0
Class A-2 Convertible Preferred Stock
Stockholders’ equity:
Preferred stock	1	1
Class A-3 Convertible Preferred Stock
Stockholders’ equity:
Preferred stock	$ 1	$ 1

CONDENSED BALANCE SHEETS (Paren

CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Preferred stock, shares authorized (in shares)	1,330,832
Preferred stock, shares issued (in shares)	1,330,832
Common stock par value (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	400,000,000	200,000,000
Common stock, shares issued (in shares)	87,040,335	67,432,712
Common stock, shares outstanding (in shares)	87,040,335	67,432,712
Class A-1 Convertible Preferred Stock
Preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	256,700	256,700
Preferred stock, shares issued (in shares)	256,700	256,700
Preferred stock, shares outstanding (in shares)	256,700	256,700
Class A-2 Convertible Preferred Stock
Preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)		1,416,453
Preferred stock, shares issued (in shares)		1,416,453
Preferred stock, shares outstanding (in shares)	1,330,832	1,416,453
Class A-3 Convertible Preferred Stock
Preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	258,707	258,707
Preferred stock, shares issued (in shares)	258,707	258,707
Preferred stock, shares outstanding (in shares)	258,707	258,707

CONDENSED STATEMENTS OF OPERATI

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Revenue, Product and Service [Extensible List]	rgls:RevenueUnderCollaborationsMember	rgls:RevenueUnderCollaborationsMember	rgls:RevenueUnderCollaborationsMember	rgls:RevenueUnderCollaborationsMember
Total revenues	$ 0	$ 0	$ 0	$ 6
Operating expenses:
Research and development	4,150	4,242	7,470	7,360
General and administrative	2,488	2,254	4,967	4,676
Total operating expenses	6,638	6,496	12,437	12,036
Loss from operations	(6,638)	(6,496)	(12,437)	(12,030)
Other income (expense):
Interest and other income	821	10	822	89
Interest and other expense	(216)	(461)	(431)	(951)
Loss before income taxes	(6,033)	(6,947)	(12,046)	(12,892)
Income tax (expense) benefit	(1)	0	(1)	8
Net loss and comprehensive loss	$ (6,034)	$ (6,947)	$ (12,047)	$ (12,884)
Net loss per share, basic (in usd per share)	$ (0.08)	$ (0.23)	$ (0.16)	$ (0.48)
Net loss per share, diluted (in usd per share)	$ (0.08)	$ (0.23)	$ (0.16)	$ (0.48)
Weighted average shares used to compute basic net loss per share (in shares)	77,175,831	29,801,974	74,249,631	26,933,173
Weighted average shares used to compute diluted net loss per share (in shares)	77,175,831	29,801,974	74,249,631	26,933,173

CONDENSED STATEMENTS OF CHANGES

CONDENSED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Accumulated deficit	Convertible preferred stock
Beginning balance (in shares) at Dec. 31, 2019		21,018,663			3,704,288
Beginning balance at Dec. 31, 2019	$ 20,015	$ 21	$ 431,305	$ (411,315)	$ 4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon vesting of restricted stock units (in shares)		21,166
Issuance of common stock upon exercise of options (in shares)		468
Issuance of common stock upon exercise of options	0
Issuance of common stock under Employee Stock Purchase Plan (in shares)		1,666
Issuance of common stock under Employee Stock Purchase Plan	1		1
Conversions of convertible preferred stock (in shares)		6,566,820			(656,682)
Conversions of convertible preferred stock	0	$ 7	(6)		$ (1)
Stock-based compensation expense	823		823
Net loss	(5,937)			(5,937)
Ending balance (in shares) at Mar. 31, 2020		27,608,783			3,047,606
Ending balance at Mar. 31, 2020	14,902	$ 28	432,123	(417,252)	$ 3
Beginning balance (in shares) at Dec. 31, 2019		21,018,663			3,704,288
Beginning balance at Dec. 31, 2019	20,015	$ 21	431,305	(411,315)	$ 4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(12,884)
Ending balance (in shares) at Jun. 30, 2020		35,922,916			2,217,963
Ending balance at Jun. 30, 2020	8,584	$ 36	432,745	(424,199)	$ 2
Beginning balance (in shares) at Mar. 31, 2020		27,608,783			3,047,606
Beginning balance at Mar. 31, 2020	14,902	$ 28	432,123	(417,252)	$ 3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon vesting of restricted stock units (in shares)		17,703
Conversions of convertible preferred stock (in shares)		8,296,430			(829,643)
Conversions of convertible preferred stock	0	$ 8	(7)		$ (1)
Stock-based compensation expense	629		629
Net loss	(6,947)			(6,947)
Ending balance (in shares) at Jun. 30, 2020		35,922,916			2,217,963
Ending balance at Jun. 30, 2020	8,584	$ 36	432,745	(424,199)	$ 2
Beginning balance (in shares) at Dec. 31, 2020		67,432,712			1,931,860
Beginning balance at Dec. 31, 2020	26,026	$ 67	453,002	(427,045)	$ 2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon vesting of restricted stock units (in shares)		16,902
Issuance of common stock upon exercise of options (in shares)		26,770
Issuance of common stock upon exercise of options	26		26
Issuance of common stock upon exercise of warrants (in shares)		2,418,681
Issuance of common stock upon exercise of warrants	666	$ 3	663
Issuance of common stock through ATM (in shares)		4,009,585
Issuance of common stock through ATM	5,713	$ 4	5,709
Issuance of common stock under Employee Stock Purchase Plan (in shares)		4,122
Issuance of common stock under Employee Stock Purchase Plan	2		2
Conversions of convertible preferred stock (in shares)		780,360			(78,036)
Conversions of convertible preferred stock	0	$ 1	(1)
Stock-based compensation expense	691		691
Net loss	(6,013)			(6,013)
Ending balance (in shares) at Mar. 31, 2021		74,689,132			1,853,824
Ending balance at Mar. 31, 2021	27,111	$ 75	460,092	(433,058)	$ 2
Beginning balance (in shares) at Dec. 31, 2020		67,432,712			1,931,860
Beginning balance at Dec. 31, 2020	26,026	$ 67	453,002	(427,045)	$ 2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(12,047)
Ending balance (in shares) at Jun. 30, 2021		87,040,335			1,846,239
Ending balance at Jun. 30, 2021	36,828	$ 87	475,831	(439,092)	$ 2
Beginning balance (in shares) at Mar. 31, 2021		74,689,132			1,853,824
Beginning balance at Mar. 31, 2021	27,111	$ 75	460,092	(433,058)	$ 2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon vesting of restricted stock units (in shares)		16,849
Issuance of common stock upon exercise of options (in shares)		958
Issuance of common stock upon exercise of options	0		0
Issuance of common stock upon exercise of warrants (in shares)		250,000
Issuance of common stock upon exercise of warrants	166	$ 0	166
Issuance of common stock through ATM (in shares)		12,007,546
Issuance of common stock through ATM	14,831	$ 12	14,819
Conversions of convertible preferred stock (in shares)		75,850			(7,585)
Conversions of convertible preferred stock	0	$ 0	0		$ 0
Stock-based compensation expense	754		754
Net loss	(6,034)			(6,034)
Ending balance (in shares) at Jun. 30, 2021		87,040,335			1,846,239
Ending balance at Jun. 30, 2021	$ 36,828	$ 87	$ 475,831	$ (439,092)	$ 2

CONDENSED STATEMENTS OF CASH FL

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities
Net loss	$ (12,047)	$ (12,884)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization expense	380	248
Stock-based compensation	1,445	1,452
Gain on PPP Loan forgiveness	(662)	0
Other	22	143
Change in operating assets and liabilities:
Contracts and other receivables	309	467
Prepaid materials	45	0
Prepaid expenses and other assets	501	647
Accounts payable	858	(297)
Accrued liabilities	(105)	(74)
Accrued research and development expenses	(335)	239
Accrued compensation	(585)	(738)
Operating lease right-of-use assets and liabilities, net	275	(72)
Contract liabilities	0	(6)
Other liabilities	(836)	(353)
Net cash used in operating activities	(10,735)	(11,228)
Investing activities
Purchases of property and equipment	(184)	0
Net cash used in investing activities	(184)	0
Financing activities
Proceeds from borrowing under Paycheck Protection Program	0	662
Proceeds from issuance of common stock, net	21,379	1
Proceeds from exercise of common stock options	27	0
Other	0	0
Payments on financing leases	(72)	(137)
Net cash provided by financing activities	21,334	526
Net increase (decrease) in cash and cash equivalents	10,415	(10,702)
Cash and cash equivalents at beginning of period	31,087	34,121
Cash and cash equivalents at end of period	41,502	23,419
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	41,440	23,419
Restricted cash	62	0
Total cash, cash equivalents and restricted cash	41,502	23,419
Supplemental disclosure of cash flow information
Paycheck Protection Program loan forgiveness	662	0
Interest paid	(222)	(728)
Income taxes (paid) refunded	$ (1)	$ 8

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In management’s opinion, the accompanying financial statements reflect all adjustments, consisting of normal recurring adjustments, considered necessary for a fair presentation of the results for the interim periods presented. Interim financial results are not necessarily indicative of results anticipated for the full year. These unaudited condensed financial statements should be read in conjunction with the audited financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2020, from which the balance sheet information herein was derived. Liquidity The accompanying financial statements have been prepared on a basis which assumes we are a going concern, and does not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classifications of liabilities that may result from any uncertainty related to our ability to continue as a going concern. Through the date of the issuance of these financial statements, we have principally been financed through proceeds received from the sale of our common stock and other equity securities, debt financings, up-front payments and milestones received from collaboration agreements, totaling $505.6 million. As of June 30, 2021, we had approximately $41.4 million of cash and cash equivalents. Based on our operating plans, we believe our cash and cash equivalents may not be sufficient to fund our operations for the period one year following the issuance of these financial statements. As a result, there is substantial doubt about our ability to continue as a going concern. All amo unts due under the Term Loan (see note 5) have been classified as a current liability as of June 30, 2021 and December 31, 2020, due to the considerations discussed above and the assessment that the material adverse change clause under the Term Loan is not within our control. In the first quarter of 2021, we received a waiver from the Lender (as defined below) with respect to noncompliance with a covenant under the Loan Agreement (as defined below). We are in compliance with all Loan Agreement covenants. We intend to seek additional capital through equity and/or debt financings, collaborative or other funding arrangements with partners or through other sources of financing. Should we seek additional financing from outside sources, we may not be able to raise such financing on terms acceptable to us or at all. If we are unable to raise additional capital when required or on acceptable terms, we may be required to scale back or discontinue the advancement of product candidates, reduce headcount, file for bankruptcy, reorganize, merge with another entity, or cease operations. If we become unable to continue as a going concern, we may have to liquidate our assets, and might realize significantly less than the values at which they are carried on our financial statements, and stockholders may lose all or part of their investment in our common stock. Use of Estimates Our condensed financial statements are prepared in accordance with GAAP, which requires us to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in our financial statements and accompanying notes. An estimated loss contingency is accrued in our financial statements if it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Although these estimates are based on our knowledge of current events and actions we may undertake in the future, actual results may ultimately differ from these estimates and assumptions. Additionally, the impact of the COVID-19 pandemic to our business and operating results presents additional uncertainty. Revenue Recognition Our revenues generally consist of upfront payments for licenses or options to obtain licenses in the future, milestone payments and payments for other research services under license and collaboration agreements. We recognize revenue when we transfer promised goods or services to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligation(s) in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligation(s) in the contract; and (v) recognize revenue when (or as) we satisfy the performance obligation(s). At contract inception, we assess the goods or services promised within each contract, assess whether each promised good or service is distinct and identify those that are performance obligations. We recognize as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Collaborative Arrangements We enter into collaborative arrangements with partners that typically include payment to us of one of more of the following: (i) license fees; (ii) payments related to the achievement of developmental, regulatory, or commercial milestones; and (iii) royalties on net sales of licensed products. Where a portion of non-refundable up-front fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as contract liabilities and recognized as revenue when (or as) the underlying performance obligation is satisfied. As part of the accounting for these arrangements, we must develop estimates and assumptions that require judgment to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligation(s). The stand-alone selling price may include items such as forecasted revenues, development timelines, discount rates, and probabilities of technical and regulatory success. We evaluate each performance obligation to determine if it can be satisfied at a point in time, or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other performance obligations, we use judgment to assess the nature of the combined performance obligation to determine whether it is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), we evaluate whether the milestones are considered probable of being reached and estimate the amount to be included in the transaction price. If it is probable that a milestone event would occur at the inception of an arrangement, the associated milestone value is included in the transaction price. Milestone payments that are contingent upon the achievement of events that are uncertain or not controllable, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received, and therefore not included in the transaction price. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which we recognize revenue as or when the performance obligations under the contract are satisfied. At the end of each reporting period, we evaluate the probability of achievement of such milestones and any related constraint(s), and if necessary, may adjust our estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which could affect license, collaboration or other revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, we have not recognized any royalty revenue resulting from any of our collaborative arrangements. Stock-Based Compensation We account for stock-based compensation expense related to stock options granted to employees and members of our board of directors by estimating the fair value of each stock option on the date of grant using the Black-Scholes option pricing model. We recognize stock-based compensation expense using the accelerated multiple-option approach. Under the accelerated multiple-option approach (also known as the graded-vesting method), we recognize compensation expense over the requisite service period for each separately vesting tranche of the award as though the award was in substance multiple awards, resulting in accelerated expense recognition over the vesting period. For performance-based awards granted to employees (i) the fair value of the award is determined on the grant date, (ii) we assess the probability of the individual milestones under the award being achieved and (iii) the fair value of the shares subject to the milestone is expensed over the implicit service period commencing once management believes the performance criteria is probable of being met. We account for restricted stock units by determining the fair value of each restricted stock unit based on the closing market price of our common stock on the date of grant. We recognize stock-based compensation expense using the accelerated multiple-option approach over the requisite service periods of the awards. Clinical Trial and Preclinical Study Accruals We make estimates of our accrued expenses for clinical trial and preclinical study activities as of each balance sheet date in our financial statements based on the facts and circumstances known to us at that time. These accruals are based upon estimates of costs incurred and fees that may be associated with services provided by clinical trial investigational sites and CROs and for other clinical trial-related activities. Payments under certain contracts with such parties depend on factors such as successful enrollment of patients, site initiation and the completion of clinical trial milestones. In accruing for these services, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If possible, we obtain information regarding unbilled services directly from these service providers. However, we may be required to estimate these services based on other information available to us. If we underestimate or overestimate the activities or fees associated with a study or service at a given point in time, adjustments to research and development expenses may be necessary in future periods. Historically, our estimated accrued liabilities have approximated actual expense incurred. Subsequent changes in estimates may result in a material change in our accruals. Prepaid Materials We capitalize the purchase of certain raw materials and related supplies for use in the manufacturing of drug product in our preclinical and clinical development programs, as we have determined that these materials have alternative future use. We can use these raw materials and related supplies in multiple clinical drug products, and therefore have future use independent of the development status of any particular drug program until it is utilized in the manufacturing process. We expense the cost of materials when used. We periodically review these capitalized materials for continued alternative future use and write down the asset to its net realizable value in the period in which an impairment is identified. Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . Subsequently, in November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments-Credit Losses . ASU 2016-13 requires entities to measure all expected credit losses for most financial assets held at the reporting date based on an expected loss model which includes historical experience, current conditions, an d reasonable and supportable forecasts. ASU 2016-13 also requires enhanced disclosures to help financial statement users better understand significant estimates and judgments used in estimating credit losses. This ASU is effective for smaller reporting companies for fiscal years beginning after December 15, 2022, with early adoption permitted. We are assessing the impact this standard will have on our financial statements and disclosures. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848), which provides guidance around reference rate reform initiatives to identify alternative reference rates that are more observable or transaction-based and less susceptible to manipulation in response to concerns about structural risks of interbank offered rates and the risk of cessation of the London Interbank Offered Rate ("LIBOR"). The amendments in the ASU provide option expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions affected by reference rate reform and apply only if such contracts, hedging relationships and other transactions that reference LIBOR or another reference rate are expected to be discontinued because of reference rate reform. The guidance does not apply to contract modifications made, and hedging relationships entered into or evaluated, after December 31, 2022. We are assessing the impact this standard will have on our financial statements and disclosures. In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, which simplifies accounting for convertible instruments by removing major separation models required under current GAAP. This standard removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and it also simplifies the diluted earnings per share calculation in certain areas. This standard is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020 and adoption must be as of the beginning of the Company’s annual fiscal year. The adoption of this standard on January 1, 2021 did not impact our financial statements or disclosures.

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per ShareBasic net loss per share is calculated by dividing net loss by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by dividing net loss by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method or if-converted method. Dilutive common stock equivalents are comprised of stock options, restricted stock units and convertible preferred stock outstanding. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted net loss per share.Potentially dilutive securities not included in the calculation of diluted net loss per common share, because to do so would be anti-dilutive, were (in common stock equivalent shares) 28,465,276 for the three months and six months ended June 30, 2021, consisting of convertible preferred stock, stock options and restricted stock units, and 28,577,380 for the three and six months ended June 30, 2020, consisting of convertible preferred stock, stock options and restricted stock units.

Investments

Investments	6 Months Ended
	Jun. 30, 2021
Debt Securities, Available-for-sale [Abstract]
Investments	InvestmentsHistorically, we have invested our excess cash primarily in debt instruments of financial institutions, corporations, U.S. government-sponsored agencies and the U.S. Treasury. We generally hold our investments to maturity and do not sell our investments before we have recovered our amortized cost basis. As of June 30, 2021 and December 31, 2020, our cash balance was comprised entirely of cash and cash equivalents (money market funds).

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We have certain financial assets recorded at fair value which have been classified as Level 1, 2, or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. Accounting standards define fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants as of the measurement date. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact, and (iv) willing to transact. The accounting standards provide an established 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 valuing the asset or liability and are developed based on market data obtained from independent sources. Unobservable inputs are inputs that reflect our assumptions about the factors that market participants would use in valuing the asset or liability. The accounting standards prioritize the inputs used in measuring the fair value into the following hierarchy: • Level 1 includes financial instruments for which quoted market prices for identical instruments are available in active markets. • Level 2 includes financial instruments for which there are inputs other than quoted prices included within Level 1 that are observable for the instrument such as quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets with insufficient volume or infrequent transactions (less active markets) or model-driven valuations in which significant inputs are observable or can be derived principally from, or corroborated by, observable market data. • Level 3 includes financial instruments for which fair value is derived from valuation techniques in which one or more significant inputs are unobservable, including management’s own assumptions. Financial Assets Measured at Fair Value The following table presents our fair value hierarchy for assets measured at fair value on a recurring basis as of June 30, 2021 and December 31, 2020 (in thousands): Fair value as of June 30, 2021 Total Level 1 Level 2 Level 3 Assets: Cash equivalents (money market funds) $ 36,903 $ 36,903 $ — $ — $ 36,903 $ 36,903 $ — $ — Fair value as of December 31, 2020 Total Level 1 Level 2 Level 3 Assets: Cash equivalents (money market funds) $ 26,901 $ 26,901 $ — $ — $ 26,901 $ 26,901 $ — $ —

Debt

Debt	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt	Debt Term Loan On June 17, 2016, we entered into a loan and security agreement ("Loan Agreement") with Oxford Finance, LLC, (the “ Lender ” ), pursuant to which we received $20.0 million in proceeds, net of debt issuance costs, on June 22, 2016 (the "Term Loan"). The outstanding Term Loan will mature on May 1, 2022 (the “Maturity Date”) and bears interest at a floating per annum rate equal to (i) 8.51% plus (ii) the greater of (a) the 30 day U.S. Dollar LIBOR rate reported in The Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue and (b) 0.44%. Under the original Loan Agreement, we were required to make interest-only payments through June 1, 2018, followed by 24 equal monthly payments of principal and unpaid accrued interest. The Loan Agreement was amended eight times between October 2017 through May 2019. On May 1, 2020 we entered into a ninth amendment to the Term Loan with the Lender (the “Ninth Amendment”). Pursuant to the terms of the Ninth Amendment, (i) the approximately $0.7 million of loan proceeds (the "PPP Loan") we received under the Paycheck Protection Program ("PPP") was included as permitted indebtedness under the terms of the Term Loan, (ii) we agreed to apply for forgiveness of the maximum amount of PPP Loan permissible in accordance with the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) and use best efforts to cause not less than $0.5 million of the PPP Loan to be forgiven by the PPP Loan lender on or before September 30, 2020 and (iii) we agreed not to amend any material provision in any document relating to the PPP Loan nor make any prepayment of the PPP Loan unless such prepayment is necessary or advisable due to change in the applicable law or guidance issued by the U.S. Small Business Administration (“SBA”). On A ugust 25, 2020 we entered into a tenth amendment to the Term Loan with the Lender (the "Tenth Amendment"). Pursuant to the terms of the Tenth Amendment, we are eligible for up to an additional seven months of interest only payments in the event we paid down $10.0 million in loan principal before April 30, 2021 (the "Principal Paydown Event"). In the event the Principal Paydown Event did not occur by April 30, 2021, we would make principal and accrued interest payments, in arrears, commencing May 1, 2021, in accordance with the terms of the Eighth Amendment. If the Principal Paydown Event occurred after April 30, 2021 but on or before July 31, 2021, we would recommence an extended interest only payment period through December 31, 2021. In the event we received the additional interest only period, principal and accrued interest payments would recommence on January 1, 2022. We received $1.0 million, $4.0 million and $5.0 million in proceeds from Sanofi (see Note 7) on September 30, 2020, October 8, 2020 and November 30, 2020, respectively. Under the terms of the Tenth Amendment, we prepaid $1.0 million, $4.0 million and $5.0 million of outstanding principal to the Lender on September 30, 2020, October 8, 2020 and November 30, 2020, respectively, for a total of $10.0 million. We also paid the applicable 5.5% final payment fees related to the three prepayments to the Lender. As the Principal Paydown Event occurred by April 30, 2021, we received an additional seven months of interest only payment extension and are not obligated to make principal payments on the Term Loan until January 1, 2022. We used the proceeds from the Term Loan solely for working capital and to fund our general business requirements. Our obligations under the Loan Agreement are secured by a first priority security interest in substantially all of our current and future assets, other than our intellectual property, for which the Lender currently has a positive lien, and certain assets under finance lease obligations. We have also agreed not to encumber our intellectual property assets, except as permitted by the Loan Agreement. The Loan Agreement includes customary events of default, including instances of a material adverse change in our operations, that may require prepayment of the outstanding Term Loan. During the first quarter of 2021, we received a waiver from the Lender with respect to noncompliance with a covenant under the Loan Agreement. As of the date of the filing of this Form 10-Q, we are in compliance with all Loan Agreement covenants as of the date of the filing of this Form 10-Q. As of June 30, 2021, $4.7 million was outstanding under the Term Loan. An additional $1.3 million is also payable at the conclusion of the Term Loan (presented in other current liabilities on our balance sheet at June 30, 2021). We had less than $0.1 million of debt issuance costs outstanding as of June 30, 2021, which are being accreted to interest expense over the life of the Term Loan using an effective interest rate of 8.98%. The exit fees are being accrued over the life of the Term Loan through interest expense. As of June 30, 2021, future principal payments for the Term Loan due under the Loan Agreement are as follows (in thousands): 2021 — 2022 4,681 $ 4,681 Paycheck Protection Program Loan On April 23, 2020, we received the proceeds from the PPP Loan in the amount of approximately $0.7 million from Silicon Valley Bank, as lender, pursuant to the PPP of the CARES Act. The PPP Loan was set to mature on April 23, 2022 and bore interest at a rate of 1.0% per annum. The PPP Loan was evidenced by a promissory note dated April 23, 2020, which contained customary events of default relating to, among other things, payment defaults and breaches of representations and warranties. The PPP Loan was prepayable by us at any time prior to maturity with no prepayment penalties. Under the CARES Act and PPP Flexibility Act, loan forgiveness is available for the sum of documented payroll costs, covered mortgage interest, covered rent payments and covered utilities during the 24 week period beginning on the date of loan disbursement. For purposes of the PPP, payroll costs exclude compensation of an individual employee in excess of $100,000, annualized, prorated for the covered period. Not more than 40% of the forgiven amount may be for non-payroll costs. Forgiveness is reduced if full-time headcount declines during the covered period as compared to specified reference periods, or if salaries and wages for employees with salaries of $100,000 or less annually are reduced by more than 25%, unless certain safe harbors are satisfied. In the event the PPP Loan, or any portion thereof, is forgiven pursuant to the PPP, the amount forgiven is applied to outstanding principal and includes accrued interest.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Stockholders' Equity	Stockholders’ Equity Common Stock As of June 30, 2021, there were 87,040,335 shares of common stock outstanding. Each share of common stock is entitled to one vote. The holders of the common stock are also entitled to receive dividends whenever funds are legally available and when declared by our Board of Directors. 2019 Equity Incentive Plan On June 15, 2019, the Company's board of directors approved, and on August 1, 2019 the Company's stockholders approved, the Company's 2019 Equity Incentive Plan (the "2019 Plan"). The 2019 Plan is intended as the successor to and continuation of the Company's 2012 Equity Incentive Plan . The number of shares authorized for issuance under the 2019 Plan may be increased by (a) the shares subject to outstanding stock awards granted under the Company’s 2009 Equity Incentive Plan (the “2009 Plan”) and the Company’s 2012 Equity Incentive Plan (together the with 2009 Plan, the “Prior Plans”) that on or after the effective date of the 2019 Plan (i) expire or terminate for any reason prior to exercise or settlement; (ii) are forfeited because of the failure to meet a contingency or condition required to vest such shares or otherwise return to the Company, or (iii) are reacquired, withheld (or not issued) to satisfy a tax withholding obligation in connection with an award or to satisfy the purchase price or exercise price of a stock award. No further grants will be made under the Prior Plan s. In addition, on January 22, 2020, an additional 4,166,860 shares of common stock became available for issuance under the 2019 Plan pu rsuant to the Milestone Closing (defined below) of the May 2019 SPA (defined below). Further, on January 1 st of each year, for a period of not more than ten years, beginning on January 1, 2021 and continuing through January 1, 2029, the number of shares authorized for issuance under the 2019 Plan will increase by 5.0% of the total number of shares of our capital stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by our Board of Directors. As of June 30, 2021, 1,023,111 shares of common stock were available for new equity award grants under the 2019 Plan and 10,002,886 shares of common stock are reserved for issuance pursuant to equity awards outstanding as of June 30, 2021. Private Placements of Common Stock, Non-Voting Preferred Stock and Warrants On May 3, 2019, we entered into a securities purchase agreement (the "May 2019 SPA") with certain institutional and other accredited investors, including certain directors, executive officers and employees of the Company (the “Purchasers”), pursuant to which we agreed to sell and issue shares of our common stock, shares of our newly designated non-voting convertible preferred stock, and warrants to purchase common stock, in up to two closings, in a private placement transaction (the “Private Placement”). At an initial closing under the May 2019 SPA that occurred on May 7, 2019 (the “Initial Closing”), we sold and issued to the Purchasers (i) 9,730,534 shares of common stock and accompanying warrants to purchase up to an aggregate of 9,730,534 shares of common stock at a combined purchase price of $1.205 per share, and (ii) 415,898 shares of non-voting Class A-1 convertible preferred stock, in lieu of shares of common stock, at a price of $10.80 per share, and accompanying warrants to purchase an aggregate of 4,158,980 shares of common stock at a price of $0.125 for each share of common stock underlying such warrants. Total gross proceeds from the Initial Closing were approximately $16.7 million, which does not include any proceeds that may be received upon exercise of the warrants. Each share of non-voting Class A-1 convertible preferred stock is convertible into 10 shares of Common Stock, subject to certain beneficial ownership conversion limitations. The warrants are exercisable for a period of five years following the date of issuance and have an exercise price of $1.08 per share, subject to proportional adjustments in the event of stock splits or combinations or similar events. The warrants are exercisable on a net exercise "cashless" basis. An aggregate of 526,083 shares of common stock and warrants to purchase up to 526,083 shares of common stock were purchased for $0.6 million by certain directors and executive officers of the Company under the Initial Closing. Pursuant to the May 2019 SPA, in the event our Board of Directors unanimously resolved to recommence our Phase 1 multiple ascending dose clinical trial of our RGLS4326 product candidate for the treatment of ADPKD (the “Phase 1 Trial”) based on correspondence from the U.S. Food and Drug Administration’s Division of Cardiovascular and Renal Products, and thereafter but on or before December 31, 2019, we made a public announcement of our plan to recommence the Phase 1 Trial (the “Public Announcement”), we would sell and the Purchasers would purchase, at a second closing under the May 2019 SPA (“Milestone Closing”), shares of our non-voting convertible preferred stock and accompanying warrants to purchase shares of Common Stock (collectively, "Milestone Securities"). On December 15, 2019, the Company's Board of Directors unanimously resolved to recommence the Phase 1 Trial based on correspondence from the U.S. Food & Drug Administration’s Division of Cardiovascular and Renal Products and on December 16, 2019, we made the related Public Announcement, triggering the Milestone Closing, which occurred on December 24, 2019. At the Milestone Closing, we sold and issued to the Purchasers 3,288,390 shares of non-voting Class A-2 convertible preferred stock and accompanying warrants to purchase an aggregate of 32,883,900 shares of common stock for an aggregate purchase price of approximately $26.0 million. Net proceeds to the Company from the Milestone Closing were approximately $24.6 million. Each share of non-voting Class A-2 convertible preferred stock is convertible into 10 shares of Common Stock, subject to certain beneficial ownership conversion limitations. The warrants will be exercisable for a period of five years following the date of issuance and have an exercise price of $0.666 per share, subject to proportional adjustments in the event of stock splits or combinations or similar events. The warrants are exercisable on a net exercise “cashless” basis. An aggregate of 121,581 shares of Class A-2 convertible preferred stock and warrants to purchase up to 1,215,810 shares of common stock were purchased for approximately $1.0 million by certain directors and executive officers of the Company under the Milestone Closing. We evaluated the non-voting Class A-1 convertible preferred stock and common stock warrants sold in the Initial Closing and the Class A-2 convertible preferred stock and common stock warrants sold in the Milestone Closing under ASC 480, Distinguishing Liabilities from Equity, and ASC 815, Derivatives and Hedging, and determined permanent equity treatment was appropriate for these freestanding financial instruments. The Initial Closing and Milestone Closing did not include any embedded features that required bifurcation. The non-voting Class A-2 convertible preferred stock and warrants issuable under the Milestone Closing were not subject to accounting recognition until the Milestone Closing occurred, as the terms of the Milestone Closing did not provide a right or an obligation on either the Company nor the Purchasers. On December 1, 2020, we entered into a Securities Purchase Agreement (the "December 2020 SPA") with certain institutional and other accredited investors, including certain directors, executive officers and employees of the Company (the “2020 Purchasers”), pursuant to which we agreed to sell and issue shares of our common stock, shares of newly designated non-voting convertible preferred stock and warrants to purchase common stock (the “2020 PIPE”). At the closing under the December 2020 SPA that occurred on December 4, 2020 (the “2020 Closing”), we sold and issued to the 2020 Purchasers (i) 24,341,607 shares of common stock and accompanying warrants to purchase up to an aggregate of 18,256,204 shares of common stock at a combined purchase price of $0.7464 per share, and (ii) 272,970 shares of non-voting Class A-3 convertible preferred stock, in lieu of shares of common stock, at a price of $6.22 per share, and accompanying warrants to purchase an aggregate of 2,047,276 shares of common stock at a price of $0.125 for each share of common stock underlying such warrants. Total gross proceeds from the 2020 Closing were approximately $19.4 million, which does not include any proceeds that may be received upon exercise of the warrants. Each share of non-voting Class A-3 convertible preferred stock is convertible into 10 shares of common stock, subject to certain beneficial ownership conversion limitations. The warrants are exercisable for a period of five years following the date of issuance and have an exercise price of $0.622 per share, subject to proportional adjustments in the event of stock splits or combinations or similar events. The warrants are exercisable on a net exercise "cashless" basis. An aggregate of 833,208 shares of common stock and warrants to purchase up to 624,906 shares of common stock were purchased for $0.6 million by certain directors and executive officers of the Company at the 2020 Closing. We evaluated the non-voting Class A-3 convertible preferred stock and common stock warrants sold in the 2020 PIPE under ASC 480, Distinguishing Liabilities from Equity, and ASC 815, Derivatives and Hedging, and determined permanent equity treatment was appropriate for these freestanding financial instruments and there were no embedded features that required bifurcation. The following table summarizes preferred stock conversions and warrant exercises (and the related impact on common stoc k) under the 2019 SPA and 2020 SPA for the three and six months ended June 30, 2021 and 2020 ( in thousands): Class A-1 Convertible Preferred Stock Class A-2 Convertible Preferred Stock Class A-3 Convertible Preferred Stock Warrants Common Stock Balance at December 31, 2020 257 1,416 259 66,038 — Conversions/Exercises — (78) — (3,920) 3,199 Balance at March 31, 2021 257 1,338 259 62,118 Conversions/Exercises — (7) — (250) 326 Balance at June 30, 2021 257 1,331 259 61,868 Balance at December 31, 2019 416 3,288 — 46,774 — Conversions/Exercises — (656) — — 6,567 Balance at March 31, 2020 416 2,632 — 46,774 Conversions/Exercises (159) (671) — — 8,296 Balance at June 30, 2020 257 1,961 — 46,774 ATM Offering On December 12, 2018, we entered into a Common Stock Sales Agreement (the “Stock Sales Agreement”) with H.C. Wainwright & Co., LLC (“HCW”), pursuant to which we may sell and issue shares of our common stock from time to time through HCW, as our sales agent (the “ATM Offering”). We have no obligation to sell any shares of common stock in the ATM Offering, and may at any time suspend offers under the Stock Sales Agreement or terminate the Stock Sales Agreement. Subject to the terms and conditions of the Stock Sales Agreement, HCW will use its commercially reasonable efforts to sell shares of our common stock from time to time based upon our instructions (including any price, time or size limits or other parameters or conditions the we may impose, subject to certain restrictions). We pay HCW a commission of 3.0% of the gross sales price of any shares sold under the Stock Sales Agreement. A total of 12,007,546 shares were sold and settled for proceeds of $14.8 million (net of $0.5 million in commissions) under the ATM Offering during the three months ended June 30, 2021. A total of 16,017,131 shares were sold and settled for proceeds of $20.5 million (net of $0.8 million in offering costs) under the ATM Offering during the six months ended June 30, 2021. No shares were sold under the ATM Offering during the three and six months ended June 30, 2020. At June 30, 2021, approximately $13.6 million remained available for sale in the ATM Offering. On August 10, 2021, we increased the amount of common stock available for sale in ATM Offerings under the Stock Sales Agreement to $50.0 million Shares Reserved for Future Issuance The following shares of common stock were reserved for future issuance as of June 30, 2021 (in thousands): Class A-1 convertible preferred stock outstanding (as-converted) 2,567 Class A-2 convertible preferred stock outstanding (as-converted) 13,308 Class A-3 convertible preferred stock outstanding (as-converted) 2,587 2019 PIPE Initial Closing warrants 12,778 2019 PIPE Milestone Closing warrants 30,595 2020 PIPE warrants 18,495 Common stock options outstanding 9,557 RSUs outstanding 446 Common stock available for future grant under 2019 Equity Incentive Plan 1,023 Employee Stock Purchase Plan 267 Total common shares reserved for future issuance 91,623 The following table summarizes our stock option and RSU (together Stock Awards) activity under all equity incentive plans for the six months ended June 30, 2021 (shares in thousands): Number of Weighted Number of Weighted average grant date fair value Stock Awards outstanding at December 31, 2020 6,813 $ 1.10 34 $ 1.50 Granted 2,973 $ 1.51 446 $ 0.95 Exercised (options) or Vested (RSUs) (28) $ 0.96 (34) $ 1.50 Canceled/forfeited/expired (201) $ 1.22 — $ 1.50 Stock Awards outstanding at June 30, 2021 9,557 $ 1.23 446 $ 0.95 Stock-Based Compensation The following table summarizes the weighted average assumptions used to estimate the fair value of stock options and performance stock awards granted to employees under our 2012 Equity Incentive Plan, 2015 Inducement Plan, 2019 Equity Incentive Plan and the shares purchasable under our Employee Stock Purchase Plan during the periods presented: Three months ended Six months ended 2021 2020 2021 2020 Stock options Risk-free interest rate 1.1 % 3.9 % 1.0 % 1.3 % Volatility 96.5 % 95.4 % 95.8 % 95.4 % Dividend yield — — — — Expected term (years) 6.1 6.1 6.1 6.1 Performance stock options Risk-free interest rate — — 1.0 % 1.4 % Volatility — — 95.7 % 95.4 % Dividend yield — — — — Expected term (years) 0 0 6.1 6.1 Employee stock purchase plan shares Risk-free interest rate 0.1 % 0.4 % 0.1 % 0.9 % Volatility 108.9 % 93.7 % 105.1 % 99.8 % Dividend yield — — — — Expected term (years) 0.5 0.5 0.5 0.5 The following table summarizes the allocation of our stock-based compensation expense for all stock awards during the periods presented (in thousands): Three months ended Six months ended 2021 2020 2021 2020 Research and development $ 229 $ 159 $ 410 $ 316 General and administrative 525 470 1,035 1,136 Total $ 754 $ 629 $ 1,445 $ 1,452

Collaborations

Collaborations	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborations	Collaborations Revenue recognized from our strategic collaborations was zero for the three and six months ended June 30, 2021, and zero and less than $0.1 million for the three and six months ended June 30, 2020, respectively. Sanofi In July 2012, we amended and restated our collaboration and license agreement with Sanofi to expand the potential therapeutic applications of the micro RNA alliance targets to be developed under such agreement. The following elements were delivered as part of the strategic collaboration with Sanofi: (1) a license for up to four micro RNA targets; and (2) a research license under our technology collaboration. In June 2013, the original research term expired, upon which we and Sanofi entered into an option agreement pursuant to which Sanofi was granted an exclusive right to negotiate the co-development and commercialization of certain of our unencumbered micro RNA programs and we were granted the exclusive right to negotiate with Sanofi for co-development and commercialization of certain miR-21 anti-miRs in oncology and Alport syndrome. In February 2014, we and Sanofi entered into a second amended and restated collaboration and license agreement (the “2014 Sanofi Amendment”) to discover, develop and commercialize micro RNA therapeutics to focus on specific orphan disease and oncology targets. Under the terms of the 2014 Sanofi Amendment, Sanofi had opt-in rights to our clinical fibrosis program targeting miR-21 for the treatment of Alport syndrome, our preclinical program targeting miR-21 for oncology indications, and our preclinical program targeting miR-221/222 for hepatocellular carcinoma (“HCC”). We were responsible for developing each of these programs to proof-of-concept, at which time Sanofi had an exclusive option on each program. If Sanofi chooses to exercise its option on any of these programs, Sanofi would reimburse us for a significant portion of our preclinical and clinical development costs and would also pay us an option exercise fee for any such program, provided that $1.25 million of the $2.5 million upfront option fee paid to us by Sanofi in connection with the June 2013 option agreement will be creditable against such option exercise fee. We are eligible to receive royalties on micro RNA therapeutic products commercialized by Sanofi and will have the right to co-promote these products relating to our preclinical program targeting miR-221/222. As indicated below, we entered into an additional amendment with Sanofi in November 2018, under which Sanofi's opt-in rights to our miR-21 programs under the 2014 Sanofi Amendment were relinquished. Sanofi's opt-in rights with regard to our miR-221/222 preclinical program under the 2014 Sanofi Amendment remained unchanged. We are eligible to receive milestone payments related to the development and commercialization of miR-221/222 for HCC of up to $38.8 million for proof-of-concept option exercise fees (net of $1.25 million creditable, as noted above), $25.0 million for clinical milestones and up to $130.0 million for regulatory and commercial milestones. In addition, we are entitled to receive royalties based on a percentage of net sales of any products from the miR-221/222 program which, in the case of sales in the United States, will be in the middle of the 10% to 20% range, and, in the case of sales outside of the United States, will range from the low end to the middle of the 10% to 20% range, depending upon the volume of sales. If we exercise our option to co-promote a miR-221/222 product, we will continue to be eligible to receive royalties on net sales of each product in the United States at the same rate, unless we elect to share a portion of Sanofi’s profits from sales of such product in the United States in lieu of royalties. In November 2018, we entered into an amendment to the 2014 Sanofi Amendment with Sanofi to modify the parties’ rights and obligations with respect to our miR-21 programs, including our RG-012 program (the “2018 Sanofi Amendment”). Under the terms of the 2018 Sanofi Amendment, we have granted Sanofi a worldwide, royalty-free, fee-bearing, exclusive license, with the right to grant sublicenses, under our know-how and patents to develop and commercialize miR-21 compounds and products for all indications, including Alport Syndrome. Sanofi will control and will assume all responsibilities and obligations for developing and commercializing each of our miR-21 programs, including our obligations regarding the administration and expense of clinical trials and all other costs, including in-license royalties and other in-license payments, related to our miR-21 programs. Under the terms of the 2018 Sanofi Amendment, we have assigned to Sanofi certain agreements, product-specific patents and all materials directed to miR-21 or to any miR-21 compound or product and are required to provide reasonable technical assistance to Sanofi for a period of 24 months after the date of the 2018 Sanofi Amendment. Under the terms of the 2018 Sanofi Amendment, we were eligible to receive approximately $6.8 million in upfront payments for the license and for miR-21 program-related materials (collectively, the “Upfront Amendment Payments”). We were also eligible to receive up to $40.0 million in development milestone payments, including a $10.0 million payment for an interim enrollment milestone (the "Enrollment Milestone"). In addition, Sanofi has agreed to reimburse us for certain out-of-pocket transition activities and assume our upstream license royalty obligations. In 2019, we completed the performance obligations under the 2018 Sanofi Amendment and recognized revenue for the $6.8 million in Upfront Amendment Payments. In August 2020, we entered into an amendment to the 2018 Sanofi Amendment (the "2020 Sanofi Amendment"). Under the terms of the 2020 Sanofi Amendment, we agreed to transfer to Sanofi additional RG-012 development program materials (the “Materials”) in exchange for a payment from Sanofi of $1.0 million (the “Transfer Payment”). In addition, in lieu of the $10.0 million Enrollment Milestone under the 2018 Sanofi Amendment, Sanofi agreed to pay us a $4.0 million milestone upon the completion of the transfer and verification of the Materials, and $5.0 million upon achievement of the Enrollment Milestone. Additionally, we are eligible to receive $25.0 million upon achievement of an additional development milestone related to Sanofi's development of the miR-21 compounds. In September 2020, we received $1.0 million in exchange for the transfer of the Materials to Sanofi, and received an additional $4.0 million in October 2020 as a result of Sanofi's completion and verification of the Materials in September 2020. As the performance obligations associated with both of these payments had been satisfied under Topic 606 as of September 30, 2020, both amounts were recognized as revenue in the third quarter of 2020. In November 2020, we received $5.0 million upon achievement of the Enrollment Milestone. As the performance obligations associated with this payment had been satisfied under Topic 606 as of December 31, 2020, this amount was recognized as revenue in the fourth quarter of 2020. As of June 30, 2021, th e $25.0 million in development milestone payments (variable consideration) is fully constrained and therefore, does not meet the criteria for revenue recognition.

Leases

Leases	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Leases	LeasesAt the inception of a contractual arrangement, we determine whether the contract contains a lease by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration over a period of time. For operating leases with an initial term greater than 12 months, we recognize operating lease right of use assets ("ROU assets") and operating lease liabilities based on the present value of lease payments over the lease term at the commencement date. Operating lease ROU assets are comprised of the lease liability plus any lease payments made and excludes lease incentives. Lease terms include options to renew or terminate the lease when we are reasonably certain that the renewal option will be exercised or when it is reasonably certain that the termination option will not be exercised. For our operating leases, we generally cannot determine the interest rate implicit in the lease, in which case we use our incremental borrowing rate as the discount rate for the lease. We estimate our incremental borrowing rate for our operating leases based on what we would normally pay to borrow on a collateralized basis over a similar term for an amount equal to the lease payments. Operating lease expense is recognized on a straight-line basis over the lease term. Leases with a lease term of 12 months or less are not recorded on the unaudited condensed balance sheet. Instead, we recognize lease expense for these leases on a straight-line basis over the lease term. Our lease agreements do not contain any material variable lease payments, residual value guarantees or restrictive covenants. Certain leases require us to pay taxes, insurance, utilities, and maintenance costs for the building, which do not represent lease components. We elected to not separate lease and non-lease components. On June 19, 2019, we entered into a lease agreement (the “Prior Lease”) with ARE SD Region No.44 LLC ("Landlord") for the lease of approximately 8,727 square feet of rentable area of the building located at 10628 Science Center Drive, Suite 225, San Diego, California 92121 (the “Prior Premises”). The commencement date of the Prior Lease was July 1, 2019 (the “Prior Commencement Date”). We used the Prior Premises as our principal executive offices and as a laboratory for research and development and other related uses. The term of the Prior Lease (the “Prior Initial Term”) was two years, six months, ending December 31, 2021. The base rent payments due for the Prior Premises were $0.4 million in 2020 and $0.4 million in 2021, net of certain rent abatement terms. We were also responsible for the payment of additional rent to cover our share of the annual operating expenses of the building, the annual tax expenses of the building and the annual utilities cost of the building. On July 1, 2019, we recorded a $0.8 million lease liability for the Prior Lease, which was calculated as the present value of future lease payments to be made under the Prior Lease. A $0.6 million ROU asset was also recorded on July 1, 2019, which represents the difference between the lease liability and the remaining $0.2 million deferred credit for the reduction of the lease liability under the operating lease agreement with Landlord dated February 25, 2019. On February 11, 2021, we entered into a lease agreement (the "Campus Point Lease") with ARE-SD Region No. 61, LLC (as successor in interest to ARE-SD Region No. 58, LLC) ("Campus Point Landlord"), for the lease of approximately 13,438 square feet of rentable area located at 4224 Campus Point Court, Suite 210, San Diego, California, 92121 (the "Campus Point Premises"). The commencement date of the Campus Point Lease was April 15, 2021. However, for accounting purposes the lease commencement date was February 11, 2021. We are using the Campus Point Premises as our new principal executive offices and as a laboratory for research and development, manufacturing and other related uses. The term of the Campus Point Lease (“Campus Point Initial Term”) is 60 months, ending April 30, 2026. The aggregate base rent due over the initial term of the Campus Point Lease is approximately $3.8 million. We are also responsible for the payment of additional amounts to cover our share of the annual operating expenses of the building, the annual tax expenses of the building and the utilities costs for the building. On February 11, 2021, concurrently with entry into the Campus Point Lease, we entered into an Assignment and Assumption of Lease (the “Assignment Agreement”) with Turning Point Therapeutics, Inc. (“Assignee”) and a Consent to Assignment (the "Consent") with Landlord. Pursuant to the Assignment Agreement, we will assign all rights, title, and interest under the New Lease to Assignee and delivered the New Premises to Assignee on April 22, 202 1. Pursuant to the Assignment Agreement, Assignee paid us $60,000 in non-refundable assignment consideration. Additionally, the Consent stipulates that we were not required to pay a fee pursuant to the Prior Lease in connection with the assignment. The execution of the Campus Point Lease, Consent, and Assignment Agreement resulted in a modification which was not accounted for as a separate contract. Rather, we accounted for the three contracts with Campus Point Landlord in combination, as they were entered into at the same time and negotiated as a package to achieve the same commercial objective. We accounted for a $0.2 million reduction in the lease liability for the Prior Lease as a deferred credit that is amortized as a reduction to rent expense over the term of the Campus Point Lease. A lease liability of less than $0.1 million and ROU asset of less than $0.1 million remained with respect to the Prior Lease and was fully amortized as of April 30, 2021. On February 11, 2021, we recorded a $3.2 million lease liability for the Campus Point Lease, which was calculated as the present value of future lease payments to be made under the Campus Point Lease. A $3.0 million ROU asset was also recorded on February 11, 2021, which represents the difference between the lease liability and the $0.2 million deferred credit for the reduction of the lease liability under the Prior Lease. Our future lease payments under operating leases at June 30, 2021 are as follows (in thousands): Operating Leases Remaining 2021 $ 341 2022 754 2023 776 2024 800 Thereafter 1,101 Total lease payments $ 3,772 Less: amount representing interest (519) Present value of obligations under leases 3,253 Less: current portion (533) Long-term lease obligations $ 2,720

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In management’s opinion, the accompanying financial statements reflect all adjustments, consisting of normal recurring adjustments, considered necessary for a fair presentation of the results for the interim periods presented. Interim financial results are not necessarily indicative of results anticipated for the full year. These unaudited condensed financial statements should be read in conjunction with the audited financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2020, from which the balance sheet information herein was derived.
Use of Estimates	Use of Estimates Our condensed financial statements are prepared in accordance with GAAP, which requires us to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in our financial statements and accompanying notes. An estimated loss contingency is accrued in our financial statements if it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Although these estimates are based on our knowledge of current events and actions we may undertake in the future, actual results may ultimately differ from these estimates and assumptions. Additionally, the impact of the COVID-19 pandemic to our business and operating results presents additional uncertainty.
Revenue Recognition	Revenue Recognition Our revenues generally consist of upfront payments for licenses or options to obtain licenses in the future, milestone payments and payments for other research services under license and collaboration agreements. We recognize revenue when we transfer promised goods or services to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligation(s) in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligation(s) in the contract; and (v) recognize revenue when (or as) we satisfy the performance obligation(s). At contract inception, we assess the goods or services promised within each contract, assess whether each promised good or service is distinct and identify those that are performance obligations. We recognize as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Collaborative Arrangements We enter into collaborative arrangements with partners that typically include payment to us of one of more of the following: (i) license fees; (ii) payments related to the achievement of developmental, regulatory, or commercial milestones; and (iii) royalties on net sales of licensed products. Where a portion of non-refundable up-front fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as contract liabilities and recognized as revenue when (or as) the underlying performance obligation is satisfied. As part of the accounting for these arrangements, we must develop estimates and assumptions that require judgment to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligation(s). The stand-alone selling price may include items such as forecasted revenues, development timelines, discount rates, and probabilities of technical and regulatory success. We evaluate each performance obligation to determine if it can be satisfied at a point in time, or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other performance obligations, we use judgment to assess the nature of the combined performance obligation to determine whether it is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), we evaluate whether the milestones are considered probable of being reached and estimate the amount to be included in the transaction price. If it is probable that a milestone event would occur at the inception of an arrangement, the associated milestone value is included in the transaction price. Milestone payments that are contingent upon the achievement of events that are uncertain or not controllable, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received, and therefore not included in the transaction price. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which we recognize revenue as or when the performance obligations under the contract are satisfied. At the end of each reporting period, we evaluate the probability of achievement of such milestones and any related constraint(s), and if necessary, may adjust our estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which could affect license, collaboration or other revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, we have not recognized any royalty revenue resulting from any of our collaborative arrangements.
Stock-Based Compensation	Stock-Based Compensation We account for stock-based compensation expense related to stock options granted to employees and members of our board of directors by estimating the fair value of each stock option on the date of grant using the Black-Scholes option pricing model. We recognize stock-based compensation expense using the accelerated multiple-option approach. Under the accelerated multiple-option approach (also known as the graded-vesting method), we recognize compensation expense over the requisite service period for each separately vesting tranche of the award as though the award was in substance multiple awards, resulting in accelerated expense recognition over the vesting period. For performance-based awards granted to employees (i) the fair value of the award is determined on the grant date, (ii) we assess the probability of the individual milestones under the award being achieved and (iii) the fair value of the shares subject to the milestone is expensed over the implicit service period commencing once management believes the performance criteria is probable of being met. We account for restricted stock units by determining the fair value of each restricted stock unit based on the closing market price of our common stock on the date of grant. We recognize stock-based compensation expense using the accelerated multiple-option approach over the requisite service periods of the awards.
Clinical Trial and Preclinical Study Accruals	Clinical Trial and Preclinical Study Accruals We make estimates of our accrued expenses for clinical trial and preclinical study activities as of each balance sheet date in our financial statements based on the facts and circumstances known to us at that time. These accruals are based upon estimates of costs incurred and fees that may be associated with services provided by clinical trial investigational sites and CROs and for other clinical trial-related activities. Payments under certain contracts with such parties depend on factors such as successful enrollment of patients, site initiation and the completion of clinical trial milestones. In accruing for these services, we estimate the time period over which services will be performed and the level of effort to be expended in each period. If possible, we obtain information regarding unbilled services directly from these service providers. However, we may be required to estimate these services based on other information available to us. If we underestimate or overestimate the activities or fees associated with a study or service at a given point in time, adjustments to research and development expenses may be necessary in future periods. Historically, our estimated accrued liabilities have approximated actual expense incurred. Subsequent changes in estimates may result in a material change in our accruals.
Prepaid Materials	Prepaid Materials We capitalize the purchase of certain raw materials and related supplies for use in the manufacturing of drug product in our preclinical and clinical development programs, as we have determined that these materials have alternative future use. We can use these raw materials and related supplies in multiple clinical drug products, and therefore have future use independent of the development status of any particular drug program until it is utilized in the manufacturing process. We expense the cost of materials when used. We periodically review these capitalized materials for continued alternative future use and write down the asset to its net realizable value in the period in which an impairment is identified.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . Subsequently, in November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments-Credit Losses . ASU 2016-13 requires entities to measure all expected credit losses for most financial assets held at the reporting date based on an expected loss model which includes historical experience, current conditions, an d reasonable and supportable forecasts. ASU 2016-13 also requires enhanced disclosures to help financial statement users better understand significant estimates and judgments used in estimating credit losses. This ASU is effective for smaller reporting companies for fiscal years beginning after December 15, 2022, with early adoption permitted. We are assessing the impact this standard will have on our financial statements and disclosures. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848), which provides guidance around reference rate reform initiatives to identify alternative reference rates that are more observable or transaction-based and less susceptible to manipulation in response to concerns about structural risks of interbank offered rates and the risk of cessation of the London Interbank Offered Rate ("LIBOR"). The amendments in the ASU provide option expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions affected by reference rate reform and apply only if such contracts, hedging relationships and other transactions that reference LIBOR or another reference rate are expected to be discontinued because of reference rate reform. The guidance does not apply to contract modifications made, and hedging relationships entered into or evaluated, after December 31, 2022. We are assessing the impact this standard will have on our financial statements and disclosures. In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, which simplifies accounting for convertible instruments by removing major separation models required under current GAAP. This standard removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and it also simplifies the diluted earnings per share calculation in certain areas. This standard is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020 and adoption must be as of the beginning of the Company’s annual fiscal year. The adoption of this standard on January 1, 2021 did not impact our financial statements or disclosures.
Fair Value Measurement	Fair Value Measurements We have certain financial assets recorded at fair value which have been classified as Level 1, 2, or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements. Accounting standards define fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants as of the measurement date. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact, and (iv) willing to transact. The accounting standards provide an established 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 valuing the asset or liability and are developed based on market data obtained from independent sources. Unobservable inputs are inputs that reflect our assumptions about the factors that market participants would use in valuing the asset or liability. The accounting standards prioritize the inputs used in measuring the fair value into the following hierarchy: • Level 1 includes financial instruments for which quoted market prices for identical instruments are available in active markets. • Level 2 includes financial instruments for which there are inputs other than quoted prices included within Level 1 that are observable for the instrument such as quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets with insufficient volume or infrequent transactions (less active markets) or model-driven valuations in which significant inputs are observable or can be derived principally from, or corroborated by, observable market data. • Level 3 includes financial instruments for which fair value is derived from valuation techniques in which one or more significant inputs are unobservable, including management’s own assumptions.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents our fair value hierarchy for assets measured at fair value on a recurring basis as of June 30, 2021 and December 31, 2020 (in thousands): Fair value as of June 30, 2021 Total Level 1 Level 2 Level 3 Assets: Cash equivalents (money market funds) $ 36,903 $ 36,903 $ — $ — $ 36,903 $ 36,903 $ — $ — Fair value as of December 31, 2020 Total Level 1 Level 2 Level 3 Assets: Cash equivalents (money market funds) $ 26,901 $ 26,901 $ — $ — $ 26,901 $ 26,901 $ — $ —

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt Maturities	As of June 30, 2021, future principal payments for the Term Loan due under the Loan Agreement are as follows (in thousands): 2021 — 2022 4,681 $ 4,681

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Activity of Shares	The following table summarizes preferred stock conversions and warrant exercises (and the related impact on common stoc k) under the 2019 SPA and 2020 SPA for the three and six months ended June 30, 2021 and 2020 ( in thousands): Class A-1 Convertible Preferred Stock Class A-2 Convertible Preferred Stock Class A-3 Convertible Preferred Stock Warrants Common Stock Balance at December 31, 2020 257 1,416 259 66,038 — Conversions/Exercises — (78) — (3,920) 3,199 Balance at March 31, 2021 257 1,338 259 62,118 Conversions/Exercises — (7) — (250) 326 Balance at June 30, 2021 257 1,331 259 61,868 Balance at December 31, 2019 416 3,288 — 46,774 — Conversions/Exercises — (656) — — 6,567 Balance at March 31, 2020 416 2,632 — 46,774 Conversions/Exercises (159) (671) — — 8,296 Balance at June 30, 2020 257 1,961 — 46,774
Common Stock Reserved for Future Issuance	The following shares of common stock were reserved for future issuance as of June 30, 2021 (in thousands): Class A-1 convertible preferred stock outstanding (as-converted) 2,567 Class A-2 convertible preferred stock outstanding (as-converted) 13,308 Class A-3 convertible preferred stock outstanding (as-converted) 2,587 2019 PIPE Initial Closing warrants 12,778 2019 PIPE Milestone Closing warrants 30,595 2020 PIPE warrants 18,495 Common stock options outstanding 9,557 RSUs outstanding 446 Common stock available for future grant under 2019 Equity Incentive Plan 1,023 Employee Stock Purchase Plan 267 Total common shares reserved for future issuance 91,623
Stock Option Activity	The following table summarizes our stock option and RSU (together Stock Awards) activity under all equity incentive plans for the six months ended June 30, 2021 (shares in thousands): Number of Weighted Number of Weighted average grant date fair value Stock Awards outstanding at December 31, 2020 6,813 $ 1.10 34 $ 1.50 Granted 2,973 $ 1.51 446 $ 0.95 Exercised (options) or Vested (RSUs) (28) $ 0.96 (34) $ 1.50 Canceled/forfeited/expired (201) $ 1.22 — $ 1.50 Stock Awards outstanding at June 30, 2021 9,557 $ 1.23 446 $ 0.95
Assumptions Used to Estimate Fair Value of Stock Options and Performance Stock and Employee Stock Purchase Plan	The following table summarizes the weighted average assumptions used to estimate the fair value of stock options and performance stock awards granted to employees under our 2012 Equity Incentive Plan, 2015 Inducement Plan, 2019 Equity Incentive Plan and the shares purchasable under our Employee Stock Purchase Plan during the periods presented: Three months ended Six months ended 2021 2020 2021 2020 Stock options Risk-free interest rate 1.1 % 3.9 % 1.0 % 1.3 % Volatility 96.5 % 95.4 % 95.8 % 95.4 % Dividend yield — — — — Expected term (years) 6.1 6.1 6.1 6.1 Performance stock options Risk-free interest rate — — 1.0 % 1.4 % Volatility — — 95.7 % 95.4 % Dividend yield — — — — Expected term (years) 0 0 6.1 6.1 Employee stock purchase plan shares Risk-free interest rate 0.1 % 0.4 % 0.1 % 0.9 % Volatility 108.9 % 93.7 % 105.1 % 99.8 % Dividend yield — — — — Expected term (years) 0.5 0.5 0.5 0.5
Stock-Based Compensation	The following table summarizes the allocation of our stock-based compensation expense for all stock awards during the periods presented (in thousands): Three months ended Six months ended 2021 2020 2021 2020 Research and development $ 229 $ 159 $ 410 $ 316 General and administrative 525 470 1,035 1,136 Total $ 754 $ 629 $ 1,445 $ 1,452

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Operating Lease, Liability, Maturity	Our future lease payments under operating leases at June 30, 2021 are as follows (in thousands): Operating Leases Remaining 2021 $ 341 2022 754 2023 776 2024 800 Thereafter 1,101 Total lease payments $ 3,772 Less: amount representing interest (519) Present value of obligations under leases 3,253 Less: current portion (533) Long-term lease obligations $ 2,720

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Accounting Policies [Abstract]
Financing from sale proceeds, debt, and agreement revenues	$ 505,600
Cash and cash equivalents	$ 41,440	$ 31,087	$ 23,419

Net Loss Per Share (Details)

Net Loss Per Share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Potentially dilutive securities not included in calculation of diluted net loss per share (in shares)	28,465,276	28,577,380	28,465,276	28,577,380

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	$ 36,903	$ 26,901
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	36,903	26,901
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Cash equivalents (money market funds)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	36,903	26,901
Cash equivalents (money market funds) | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	36,903	26,901
Cash equivalents (money market funds) | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	0	0
Cash equivalents (money market funds) | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets measured at fair value on a recurring basis	$ 0	$ 0

Debt (Narrative) (Details)

Debt (Narrative) (Details)	Nov. 30, 2020USD ($)	Oct. 08, 2020USD ($)	Sep. 30, 2020USD ($)	Aug. 25, 2020USD ($)	Jun. 22, 2016USD ($)	Jun. 17, 2016number_of_payment	Jun. 30, 2021USD ($)prepayments	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)prepayments	Jun. 30, 2020USD ($)	May 31, 2019times	May 01, 2020USD ($)	Apr. 23, 2020USD ($)
Debt Instrument [Line Items]
Number of times | times											8
Total revenues							$ 0	$ 0	$ 0	$ 6,000
Revenue under collaborations
Debt Instrument [Line Items]
Total revenues							0	$ 0	0	$ 100,000
Revenue under collaborations | Sanofi
Debt Instrument [Line Items]
Total revenues	$ 5,000,000	$ 4,000,000	$ 1,000,000
Debt Financing Agreement
Debt Instrument [Line Items]
Proceeds from borrowing under term loan					$ 20,000,000
Stated interest rate, percentage						8.51%
Number of monthly payments | number_of_payment						24
Long-term debt							4,700,000		4,700,000
Debt fee							1,300,000		1,300,000
Debt issuance costs							$ 100,000		$ 100,000
Debt instrument effective rate							8.98%		8.98%
Debt Financing Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate, percentage						0.44%
PPP Loan
Debt Instrument [Line Items]
PPP loan												$ 700,000
Forgiveness threshold amount												$ 500,000
PPP Loan | Other Current Liabilities
Debt Instrument [Line Items]
Long-term debt													$ 700,000
Tenth Amendment
Debt Instrument [Line Items]
Interest-only payment extension				7 months
Prepayment requirement				$ 10,000,000
Term Loan
Debt Instrument [Line Items]
Repayments of debt	$ 5,000,000	$ 4,000,000	$ 1,000,000						$ 10,000,000
Payment fee							5.50%		5.50%
Number of prepayments to lender | prepayments							3		3
Additional extension for interest only payments									7 months

Debt (Future Principal Payments

Debt (Future Principal Payments) (Details) - Debt Financing Agreement Tranche A $ in Thousands	Jun. 30, 2021USD ($)
Debt Instrument [Line Items]
2021	$ 0
2022	4,681
Long-term Debt	$ 4,681

Stockholders' Equity (Narrative

Stockholders' Equity (Narrative) (Details) $ / shares in Units, $ in Millions	Dec. 04, 2020USD ($)$ / sharesshares	Jan. 22, 2020shares	Dec. 24, 2019USD ($)$ / sharesshares	May 07, 2019USD ($)$ / sharesshares	Jun. 30, 2021voteshares	Dec. 31, 2020shares	May 03, 2019closing
Subsidiary, Sale of Stock [Line Items]
Common stock, shares outstanding (in shares)					87,040,335	67,432,712
Common stock voting rights votes | vote					1
Number of years for increase of authorized shares		10 years
Total common shares reserved for future issuance (in shares)					91,623,000
Number of closings | closing							2
Private Placement
Subsidiary, Sale of Stock [Line Items]
Share sold (in shares)	24,341,607			9,730,534
Warrants callable (in shares)	18,256,204			9,730,534
Sale of stock price (in usd per share) | $ / shares	$ 0.7464			$ 1.205
Consideration received | $	$ 19.4			$ 16.7
Shares issued upon conversion (in shares)	10			10
Warrants, term				5 years
Warrant exercise price (in usd per share) | $ / shares				$ 1.08
Milestone Closing
Subsidiary, Sale of Stock [Line Items]
Consideration received | $			$ 24.6
Preferred Class A | Private Placement
Subsidiary, Sale of Stock [Line Items]
Warrants callable (in shares)				4,158,980
Sale of stock price (in usd per share) | $ / shares				$ 10.80
Nonvoting convertible preferred stock issued (in shares)				415,898
Class A-2 Convertible Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Reverse stock split ratio			10
Class A-2 Convertible Preferred Stock | Milestone Closing
Subsidiary, Sale of Stock [Line Items]
Share sold (in shares)			3,288,390
Warrants callable (in shares)			32,883,900
Consideration received | $			$ 26
Warrants, term			5 years
Warrant exercise price (in usd per share) | $ / shares			$ 0.666
Class A-3 Convertible Preferred Stock | Private Placement
Subsidiary, Sale of Stock [Line Items]
Warrants callable (in shares)	2,047,276
Sale of stock price (in usd per share) | $ / shares	$ 6.22
Nonvoting convertible preferred stock issued (in shares)	272,970
Warrants, term	5 years
Warrant exercise price (in usd per share) | $ / shares	$ 0.622
Warrants | Preferred Class A | Private Placement
Subsidiary, Sale of Stock [Line Items]
Sale of stock price (in usd per share) | $ / shares				$ 0.125
Warrants | Class A-3 Convertible Preferred Stock | Private Placement
Subsidiary, Sale of Stock [Line Items]
Sale of stock price (in usd per share) | $ / shares	$ 0.125
Certain Directors and Executive Officers | Private Placement
Subsidiary, Sale of Stock [Line Items]
Share sold (in shares)	833,208			526,083
Certain Directors and Executive Officers | Preferred Class A | Private Placement
Subsidiary, Sale of Stock [Line Items]
Warrants callable (in shares)				526,083
Proceeds from issuance of right to purchase common shares | $				$ 0.6
Certain Directors and Executive Officers | Class A-2 Convertible Preferred Stock | Milestone Closing
Subsidiary, Sale of Stock [Line Items]
Share sold (in shares)			121,581
Warrants callable (in shares)			1,215,810
Consideration received | $			$ 1
Certain Directors and Executive Officers | Class A-3 Convertible Preferred Stock | Private Placement
Subsidiary, Sale of Stock [Line Items]
Warrants callable (in shares)	624,906
Proceeds from issuance of right to purchase common shares | $	$ 0.6
2019 Plan
Subsidiary, Sale of Stock [Line Items]
Number of additional shares authorized (in shares)		4,166,860
Number of additional shares authorized yearly increase		5.00%
Common stock available for future grant (in shares)					1,023,111
Total common shares reserved for future issuance (in shares)					10,002,886

Stockholders' Equity (Share Act

Stockholders' Equity (Share Activity) (Details) - shares	3 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020
Activity of Shares [Roll Forward]
Common stock, shares outstanding (in shares)		67,432,712
Common stock, shares outstanding (in shares)	87,040,335
Class A-1 Convertible Preferred Stock | 2019 SPA and 2020 SPA
Activity of Shares [Roll Forward]
Preferred stock, shares outstanding (in shares)	257,000	257,000	416,000	416,000
Conversions/Exercises (in shares)	0	0	(159,000)	0
Preferred stock, shares outstanding (in shares)	257,000	257,000	257,000	416,000
Class A-2 Convertible Preferred Stock | 2019 SPA and 2020 SPA
Activity of Shares [Roll Forward]
Preferred stock, shares outstanding (in shares)	1,338,000	1,416,000	2,632,000	3,288,000
Conversions/Exercises (in shares)	(7,000)	(78,000)	(671,000)	(656,000)
Preferred stock, shares outstanding (in shares)	1,331,000	1,338,000	1,961,000	2,632,000
Class A-3 Convertible Preferred Stock | 2019 SPA and 2020 SPA
Activity of Shares [Roll Forward]
Preferred stock, shares outstanding (in shares)	259,000	259,000	0	0
Conversions/Exercises (in shares)	0	0	0	0
Preferred stock, shares outstanding (in shares)	259,000	259,000	0	0
Warrants | 2019 SPA and 2020 SPA
Activity of Shares [Roll Forward]
Warrants outstanding (in shares)	62,118,000	66,038,000	46,774,000	46,774,000
Conversions/Exercises (in shares)	(250,000)	(3,920,000)	0	0
Warrants outstanding (in shares)	61,868,000	62,118,000	46,774,000	46,774,000
Common Stock | 2019 SPA and 2020 SPA
Activity of Shares [Roll Forward]
Common stock, shares outstanding (in shares)		0		0
Conversions/Exercises (in shares)	(326,000)	(3,199,000)	(8,296,000)	(6,567,000)
Common stock, shares outstanding (in shares)

Stockholders' Equity (ATM Offer

Stockholders' Equity (ATM Offering) (Details) - At The Moment - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Aug. 10, 2021	Dec. 12, 2018
Class of Stock [Line Items]
Commission fee rate						3.00%
Share sold (in shares)	12,007,546	0	16,017,131	0
Consideration received	$ 14.8		$ 20.5
Payments for commissions	0.5		0.8
Amount eligible to be drawn down under the ATM	$ 13.6		$ 13.6
Subsequent Event
Class of Stock [Line Items]
Amount eligible to be drawn down under the ATM					$ 50

Stockholders' Equity (Common St

Stockholders' Equity (Common Stock Reserved for Future Issuance) (Details) shares in Thousands	Jun. 30, 2021shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock options outstanding (in shares)	9,557
Total common shares reserved for future issuance (in shares)	91,623
Common stock available for future grant under 2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for future grant (in shares)	1,023
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for future grant (in shares)	267
RSUs outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs outstanding (in shares)	446
Class A-1 convertible preferred stock outstanding (as-converted)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares outstanding (in shares)	2,567
Class A-2 convertible preferred stock outstanding (as-converted)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares outstanding (in shares)	13,308
Class A-3 convertible preferred stock outstanding (as-converted)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares outstanding (in shares)	2,587
2019 PIPE Initial Closing warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding (in shares)	12,778
2019 PIPE Milestone Closing warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding (in shares)	30,595
2020 PIPE warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants outstanding (in shares)	18,495

Stockholders' Equity (Stock Opt

Stockholders' Equity (Stock Option and RSU Activity) (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Number of options
Ending outstanding number (in shares)	9,557
Stock options
Number of options
Beginning outstanding number (in shares)	6,813
Granted (in shares)	2,973
Exercised (options) or Vested (RSUs) (in shares)	(28)
Canceled/forfeited/expired (in shares)	(201)
Ending outstanding number (in shares)	9,557
Weighted average exercise price
Beginning balance (in usd per share) | $ / shares	$ 1.10
Granted (in usd per share) | $ / shares	1.51
Exercised (options) or Vested (RSUs) (in usd per share) | $ / shares	0.96
Canceled/forfeited/expired (in usd per share) | $ / shares	1.22
Ending balance (in usd per share) | $ / shares	$ 1.23
Restricted Stock Units (RSUs)
Number of RSUs
Beginning balance (in shares)	34
Shares granted (in shares)	446
Exercised (options) or Vested (RSUs) (in shares)	(34)
Canceled/forfeited/expired (in shares)	0
Ending balance (in shares)	446
Weighted average grant date fair value
Beginning balance (in usd per share) | $ / shares	$ 1.50
Granted (in usd per share) | $ / shares	0.95
Exercised (options) or Vested (RSUs)(in usd per share) | $ / shares	1.50
Canceled/forfeited/expired (in usd per share) | $ / shares	1.50
Ending balance (in usd per share) | $ / shares	$ 0.95

Stockholders' Equity (Assumptio

Stockholders' Equity (Assumptions Used to Estimate Fair Value of Stock Options and Performance Stock and Employee Stock Purchase Plan) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock options
Weighted average assumptions
Risk-free interest rate	1.10%	3.90%	1.00%	1.30%
Volatility	96.50%	95.40%	95.80%	95.40%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days
Performance stock options
Weighted average assumptions
Risk-free interest rate	0.00%	0.00%	1.00%	1.40%
Volatility	0.00%	0.00%	95.70%	95.40%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (years)	0 months	0 months	6 years 1 month 6 days	6 years 1 month 6 days
Employee stock purchase plan shares
Weighted average assumptions
Risk-free interest rate	0.10%	0.40%	0.10%	0.90%
Volatility	108.90%	93.70%	105.10%	99.80%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (years)	6 months	6 months	6 months	6 months

Stockholders' Equity (Stock-Bas

Stockholders' Equity (Stock-Based Compensation Expense Allocation) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	$ 754	$ 629	$ 1,445	$ 1,452
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	229	159	410	316
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expenses	$ 525	$ 470	$ 1,035	$ 1,136

Collaborations (Details)

Collaborations (Details)

1 Months Ended

3 Months Ended

6 Months Ended

12 Months Ended

Oct. 31, 2020USD ($)

Sep. 30, 2020USD ($)

Aug. 31, 2020USD ($)

Nov. 30, 2018USD ($)

Feb. 28, 2014USD ($)

Jun. 30, 2013USD ($)

Jul. 31, 2012target

Jun. 30, 2021USD ($)

Jun. 30, 2020USD ($)

Jun. 30, 2021USD ($)

Jun. 30, 2020USD ($)

Dec. 31, 2019USD ($)

Nov. 30, 2020USD ($)

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Revenues (less than in 2020)

$ 0

$ 0

$ 0

$ 6,000

Revenue under collaborations

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Revenues (less than in 2020)

0

$ 0

0

$ 100,000

Sanofi

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Number of collaborative areas granted | target

4

Initial upfront option payment

$ 4,000,000

$ 1,000,000

$ 1,000,000

Potential revenue through milestone payments

$ 6,800,000

Agreement period

24 months

Upfront payment non-creditable portion recognized

$ 6,800,000

Enrollment Milestone

10,000,000

Contract with customer, asset

$ 5,000,000

Development milestone not achievable

25,000,000

$ 25,000,000

Sanofi | Minimum | United States

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Royalties based on percentage of net sales

10.00%

Sanofi | Minimum | Outside of the United States

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Royalties based on percentage of net sales

10.00%

Sanofi | Maximum | United States

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Royalties based on percentage of net sales

20.00%

Sanofi | Maximum | Outside of the United States

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Royalties based on percentage of net sales

20.00%

Sanofi | Development Commercialization And License Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Deferred revenue creditable against future milestones

$ 1,250,000

$ 1,250,000

Initial upfront option payment

$ 2,500,000

Sanofi | Proof-of-Concept Trial

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Potential revenue through milestone payments

38,800,000

38,800,000

Sanofi | Clinical

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Potential revenue through milestone payments

25,000,000

25,000,000

Sanofi | Regulatory and Commercialization Milestones

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Potential revenue through milestone payments

$ 130,000,000

$ 130,000,000

Sanofi | Development Milestones

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Potential revenue through milestone payments

25,000,000

$ 40,000,000

Sanofi | Enrollment Milestone

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Potential revenue through milestone payments

$ 10,000,000

Sanofi | Materials Sold

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Potential revenue through milestone payments

4,000,000

Sanofi | Achievement of Enrollment Milestone

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Potential revenue through milestone payments

$ 5,000,000

Leases (Narrative) (Details)

Leases (Narrative) (Details) $ in Thousands	Feb. 11, 2021USD ($)ft²contract	Jun. 30, 2021USD ($)	Apr. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Jul. 01, 2019USD ($)	Jun. 19, 2019USD ($)ft²
Lessee, Lease, Description [Line Items]
Remaining 2021		$ 341
Base rent payments due 2021		754
ROU asset		2,814		$ 253
Operating lease payments due		$ 3,772
Prior Premises
Lessee, Lease, Description [Line Items]
Net rentable area | ft²						8,727
Term of contract						2 years 6 months
Remaining 2021						$ 400
Base rent payments due 2021						$ 400
Initial direct cost liability					$ 800
ROU asset					600
Deferred credit, operating lease liabilities					$ 200
Campus Point Lease
Lessee, Lease, Description [Line Items]
Term of contract	60 months
Initial direct cost liability	$ 3,200		$ 100
ROU asset	3,000		100
Deferred credit, operating lease liabilities	$ 200
Rented area | ft²	13,438
Operating lease payments due	$ 3,800
Nonrefundable lease cost for assignment	$ 60
Number of operating lease contracts | contract	3
Deferred cost of liability			$ 200

Leases (Operating and Finance M

Leases (Operating and Finance Maturities) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Remaining 2021	$ 341
2022	754
2023	776
2024	800
Thereafter	1,101
Total lease payments	3,772
Less: amount representing interest	(519)
Present value of obligations under leases	3,253
Less: current portion	(533)
Long-term lease obligations	$ 2,720	$ 0