atra-10q_20220331.htm

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

☒	QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended March 31, 2022

☐	TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission file number 001-36548

ATARA BIOTHERAPEUTICS, INC.

(Exact name of Registrant as specified in its Charter)

Delaware		46-0920988
(State or other jurisdiction of incorporation or organization)		(I.R.S. Employer Identification No.)

611 Gateway Blvd., Suite 900 South San Francisco, CA		94080
(Address of principal executive offices)		(Zip Code)

Registrant’s telephone number, including area code: (650) 278-8930

Securities registered pursuant to Section 12(b) of the Act:

Title of Each Class		Trading Symbol(s)		Name of Each Exchange on Which Registered
Common Stock, par value $0.0001 per share		ATRA		The Nasdaq Stock Market LLC

Indicate by check mark whether the Registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	☒	Accelerated filer	☐
Non-accelerated filer	☐	Smaller reporting company	☐
Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

The number of outstanding shares of the Registrant’s Common Stock as of April 25, 2022 was 93,405,726 shares.

ATARA BIOTHERAPEUTICS, INC.

INDEX

		Page
PART I.	FINANCIAL INFORMATION

Item 1.	Financial Statements (Unaudited)

	Condensed Consolidated Balance Sheets	5

	Condensed Consolidated Statements of Operations and Comprehensive Loss	6

	Condensed Consolidated Statements of Changes in Stockholders’ Equity	7

	Condensed Consolidated Statements of Cash Flows	8

	Notes to Condensed Consolidated Financial Statements	9

Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	20

Item 3.	Quantitative and Qualitative Disclosures about Market Risk	30

Item 4.	Controls and Procedures	30

PART II.	OTHER INFORMATION	31

Item 1.	Legal Proceedings	31

Item 1A.	Risk Factors	31
Item 6.	Exhibits	73

	Signatures	74

NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q contains forward-looking statements within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. Such forward-looking statements, which represent our intent, belief or current expectations, involve risks and uncertainties and other factors that could cause actual results and the timing of certain events to differ materially from future results expressed or implied by such forward-looking statements. In some cases you can identify these statements by forward-looking words such as “believe,” “may,” “will,” “estimate,” “continue,” “anticipate,” “intend,” “could,” “would,” “project,” “predict,” “plan,” “expect” or the negative or plural of these words or similar expressions. The forward-looking statements include, but are not limited to, statements about:

•

our expectations regarding the timing of initiating clinical studies, opening client sites, enrolling clinical studies and reporting results of clinical studies for our programs, including in light of the COVID-19 pandemic;

•

the likelihood and timing of regulatory submissions or related approvals for our product candidates, including the initiation, completion and expectations about the timing of approvals for our biologics license application (BLA) and marketing authorization application (MAA) for tab-cel^® for patients with Epstein-Barr virus with post-transplant lymphoproliferative disease (EBV+ PTLD);

•

the potential indications for our product candidates, if approved for commercial use;

•

the potential market opportunities for commercializing our product candidates;

•

our Research, Development and License Agreement with Bayer AG, including potential milestone and royalty payments under the agreement;

•

our Commercialization Agreement with Pierre Fabre Medicament, including potential milestone and royalty payments under the agreement;

•

our Asset Purchase Agreement and related transactions with FUJIFILM Diosynth Biotechnologies California, Inc., including the Master Services and Supply Agreement;

•

our expectations regarding the potential market size and the size of the patient populations for our product candidates, if approved for commercial use;

•

estimates of our expenses, capital requirements and need for additional financing;

•

our expectation regarding the length of time that our existing capital resources will be sufficient to enable us to fund our planned operations;

•

our ability to commercialize our product candidates, if approved for commercial use;

•

our ability to develop, acquire and advance product candidates into, and successfully complete, clinical studies;

•

the initiation, timing, costs, progress and results of future preclinical studies and clinical studies and our research and development programs;

•

our ability to enter into and maintain contracts with clinical research organizations, manufacturing organizations and other vendors for clinical and pre-clinical studies, supplies and other services;

•

the scope of protection we are able to obtain and maintain for the intellectual property rights covering our product candidates;

•

our financial performance;

•

developments and projections relating to our competitors and our industry;

•

our ability to have our product candidates manufactured for our clinical studies, or if approved, for commercial sale;

•

the impact of COVID-19 to our business and operations, as well as the businesses and operations of third parties on which we rely;

•

our ability to sell or have manufactured approved products at commercially reasonable values; and

•

timing and costs related to qualification of our CMOs’ manufacturing facilities for commercial production.

These statements are only current predictions and are subject to known and unknown risks, uncertainties, including, without limitation, risks and uncertainties associated with the costly and time-consuming pharmaceutical product development process and the uncertainty of clinical success; the COVID-19 pandemic, which may significantly impact (i) our business, research, clinical

development plans and operations, including our operations in South San Francisco and Southern California and at our clinical trial sites, as well as the business or operations of our third-party manufacturers, contract research organizations or other third parties with whom we conduct business, (ii) our ability to access capital, and (iii) the value of our common stock; the sufficiency of our cash resources and need for additional capital, and other factors that may cause our or our industry’s actual results, levels of activity, performance or achievements to be materially different from those anticipated by the forward-looking statements. We discuss many of these risks in this report in greater detail under the heading “1A. Risk Factors” and elsewhere in this report. You should not rely upon forward-looking statements as predictions of future events. New risk factors and uncertainties may emerge from time to time, and it is not possible for management to predict all risks and uncertainties.

In this Quarterly Report on Form 10-Q, unless the context requires otherwise, “Atara,” “Atara Biotherapeutics,” “Company,” “we,” “our,” and “us” means Atara Biotherapeutics, Inc. and, where appropriate, its subsidiaries.

Summary Risk Factors

Our business is subject to numerous risks and uncertainties that may have a material adverse effect on our business, financial condition or results of operations. These risks are more fully described below. These risks include, among others:

•

we have incurred substantial losses since our inception and anticipate that we will continue to incur substantial and increasing losses for the foreseeable future;

•

we currently have no approved products and thus have no revenues from commercialization of any products and may never generate revenues from the commercial sale of products or achieve profitability;

•

we are generally early in our development efforts, have only a small number of product candidates in clinical development, and we will need to successfully complete preclinical and clinical testing of our product candidates before we can seek regulatory approval and potentially generate commercial sales;

•

we will require substantial additional financing to achieve our goals, which may not be available to us on acceptable terms, or at all;

•

our future success depends on our ability to retain our executive officers and to attract, retain and motivate qualified personnel;

•

the results of preclinical studies or earlier clinical studies are not necessarily predictive of future results, and our existing product candidates in clinical studies, and any other product candidates we advance into clinical studies may not have favorable results in later clinical studies or receive regulatory approval;

•

clinical drug development, both in the U.S. and international jurisdictions, involves a lengthy and expensive process with an uncertain outcome and even if our product candidates receive regulatory approval, they may still face future development and regulatory difficulties;

•

our T-cell immunotherapy product candidates and our next-generation CAR T programs represent new therapeutic approaches that could result in heightened regulatory scrutiny and delays in or our inability to achieve regulatory approval, commercialization or payor coverage of our product candidates;

•

there can be no assurance that we will achieve all of the anticipated benefits of the Fujifilm Transaction and we could face unanticipated challenges;

•

the market opportunities for our product candidates may be limited to those patients who are ineligible for or have failed prior treatments and may be small;

•

we may not be able to obtain or maintain orphan drug exclusivity for our product candidates;

•

the COVID-19 pandemic continues to impact our business and operations and could materially and adversely affect our business and operations in the future, as well as the businesses and operations of third parties on which we rely;

•

our success depends upon our ability to obtain and maintain sufficient intellectual property protection for our product candidates, and we may not be able to protect our intellectual property rights throughout the world;

•

our principal stockholders own a significant percentage of our stock and will be able to exert significant control over matters subject to stockholder approval; and

•

we may not be able to obtain and maintain the relationships with third parties that are necessary to develop, commercialize and manufacture some or all of our product candidates.

Atara Biotherapeutics, Inc.

Condensed Consolidated Balance Sheets

(Unaudited)

(In thousands, except per share amounts)

	March 31,			December 31,
	2022			2021
Assets
Current assets:
Cash and cash equivalents	$	101,669		$	106,084
Short-term investments		200,142			264,984
Restricted cash		146			194
Accounts receivable		668			986
Prepaid expenses and other current assets		11,574			12,373
Assets held for sale		190			—
Total current assets		314,389			384,621
Property and equipment, net		9,109			53,780
Operating lease assets		18,933			26,159
Restricted cash - long-term		1,200			1,200
Other assets		2,220			2,367
Long-term assets held for sale		51,429			—
Total assets	$	397,280		$	468,127

Liabilities and stockholders’ equity
Current liabilities:
Accounts payable	$	11,945		$	17,368
Accrued compensation		16,381			25,150
Accrued research and development expenses		13,990			13,451
Deferred revenue		50,943			40,760
Other current liabilities		8,051			9,057
Liabilities held for sale		252			—
Total current liabilities		101,562			105,786
Deferred revenue - long-term		45,000			55,708
Operating lease liabilities - long-term		17,453			25,518
Other long-term liabilities		616			1,501
Long-term liabilities held for sale		8,333			—
Total liabilities		172,964			188,513

Commitments and contingencies (Note 8)

Stockholders’ equity:
Common stock—$0.0001 par value, 500,000 shares authorized as of March 31, 2022 and December 31, 2021; 93,406 and 91,671 shares issued and outstanding as of March 31, 2022 and December 31, 2021, respectively		9			9
Additional paid-in capital		1,779,026			1,744,695
Accumulated other comprehensive (loss) income		(1,892	)		(368	)
Accumulated deficit		(1,552,827	)		(1,464,722	)
Total stockholders’ equity		224,316			279,614
Total liabilities and stockholders’ equity	$	397,280		$	468,127

See accompanying notes.

Atara Biotherapeutics, Inc.

Condensed Consolidated Statements of Operations and Comprehensive Loss

(Unaudited)

(In thousands, except per share amounts)

	Three Months Ended March 31,
	2022			2021
License and collaboration revenue	$	7,314		$	3,552
Operating expenses:
Research and development		74,963			64,059
General and administrative		20,571			17,738
Total operating expenses		95,534			81,797
Loss from operations		(88,220	)		(78,245	)
Interest and other income (expense), net		115			(90	)
Loss before provision for income taxes		(88,105	)		(78,335	)
Provision for income taxes		—			—
Net loss	$	(88,105	)	$	(78,335	)
Other comprehensive gain (loss):
Unrealized gain (loss) on available-for-sale securities		(1,524	)		(135	)
Comprehensive loss	$	(89,629	)	$	(78,470	)
Net loss per common share:
Basic and diluted net loss per common share	$	(0.87	)	$	(0.86	)

Weighted-average shares outstanding used to calculate basic and diluted net loss per common share		100,726			91,456

See accompanying notes.

Atara Biotherapeutics, Inc.

Condensed Consolidated Statements of Changes in Stockholders’ Equity

(Unaudited)

(In thousands)

								Accumulated
	Common				Additional			Other						Total
	Stock				Paid-in			Comprehensive			Accumulated			Stockholders’
For the Three Months Ended March 31, 2022	Shares		Amount		Capital			Income (Loss)			Deficit			Equity
Balance as of January 1, 2022		91,671	$	9	$	1,744,695		$	(368	)	$	(1,464,722	)	$	279,614
Issuance of common stock through ATM facilities, net of commissions and offering costs of $419		1,320		—		20,516			—			—			20,516
RSU settlements, net of shares withheld		405		—		(616	)		—			—			(616	)
Issuance of common stock pursuant to employee stock awards		10		—		96			—			—			96
Stock-based compensation expense		—		—		14,335			—			—			14,335
Net loss		—		—		—			—			(88,105	)		(88,105	)
Unrealized loss on available-for-sale securities		—		—		—			(1,524	)		—			(1,524	)
Balance as of March 31, 2022		93,406	$	9	$	1,779,026		$	(1,892	)	$	(1,552,827	)	$	224,316

								Accumulated
	Common				Additional			Other						Total
	Stock				Paid-in			Comprehensive			Accumulated			Stockholders’
For the Three Months Ended March 31, 2021	Shares		Amount		Capital			Income (Loss)			Deficit			Equity
Balance as of January 1, 2021		83,372	$	8	$	1,586,616		$	296		$	(1,124,581	)	$	462,339
Issuance of common stock through ATM facilities, net of commissions and offering costs of $139		146		—		2,382			—			—			2,382
RSU settlements, net of shares withheld		449		—		(1,231	)		—			—			(1,231	)
Issuance of common stock pursuant to employee stock awards		108		—		1,749			—			—			1,749
Stock-based compensation expense		—		—		12,268			—			—			12,268
Net loss		—		—		—			—			(78,335	)		(78,335	)
Unrealized loss on available-for-sale securities		—		—		—			(135	)		—			(135	)
Balance as of March 31, 2021		84,075	$	8	$	1,601,784		$	161		$	(1,202,916	)	$	399,037

See accompanying notes.

Atara Biotherapeutics, Inc.

Condensed Consolidated Statements of Cash Flows

(Unaudited)

(In thousands)

	Three Months Ended March 31,
	2022			2021
Operating activities
Net loss	$	(88,105	)	$	(78,335	)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense		14,335			12,268
Depreciation and amortization expense		1,591			2,222
Amortization of investment premiums		498			360
Non-cash operating lease expense		627			373
Asset retirement obligation accretion expense		7			21
Changes in operating assets and liabilities:
Accounts receivable		318			(8,360	)
Prepaid expenses and other current assets		609			1,828
Other assets		51			38
Accounts payable		(4,588	)		9,555
Accrued compensation		(8,769	)		(7,672	)
Accrued research and development expenses		539			(5,158	)
Other current liabilities		(570	)		1,510
Deferred revenue		(525	)		6,058
Operating lease liabilities		(645	)		(406	)
Other long-term liabilities		98			—
Net cash used in operating activities		(84,529	)		(65,698	)
Investing activities
Purchases of short-term investments		(26,427	)		(94,055	)
Proceeds from maturities and sales of short-term investments		89,247			109,751
Purchases of property and equipment		(2,605	)		(2,197	)
Net cash provided by (used in) investing activities		60,215			13,499
Financing activities
Proceeds from issuance of common stock through ATM facilities, net		20,539			2,457
Proceeds from employee stock awards		96			1,749
Taxes paid related to net share settlement of restricted stock units		(616	)		(1,231	)
Principal payments on finance lease obligations		(64	)		(66	)
Other financing activities, net		(104	)		(17	)
Net cash provided by financing activities		19,851			2,892
Decrease in cash, cash equivalents and restricted cash		(4,463	)		(49,307	)
Cash, cash equivalents and restricted cash at beginning of period		107,478			201,798
Cash, cash equivalents and restricted cash at end of period	$	103,015		$	152,491
Non-cash investing and financing activities
Property and equipment purchases included in accounts payable and other accrued liabilities	$	1,188		$	1,245
Accrued costs related to underwritten public offering	$	—		$	176
Accrued costs related to ATM facilities	$	23		$	75
Supplemental cash flow disclosure
Cash paid for interest	$	5		$	10
Cash paid for income taxes	$	14		$	8

See accompanying notes.

Atara Biotherapeutics, Inc.

Notes to Condensed Consolidated Financial Statements

(Unaudited)

1.	Description of Business

Atara Biotherapeutics, Inc. (“Atara”, “we”, “our” or “the Company”) was incorporated in August 2012 in Delaware. Atara is a pioneer in T-cell immunotherapy, leveraging its novel allogeneic Epstein-Barr Virus (“EBV”) T-cell platform to develop transformative therapies for patients with serious diseases, including solid tumors, hematologic cancers and autoimmune disease.

We have several T-cell immunotherapies in clinical development and are progressing multiple next-generation allogeneic chimeric antigen receptor T-cell (“CAR T”) programs. Our most advanced T-cell immunotherapy program, tab-cel^® (tabelecleucel), is currently in Phase 3 development, and in October 2021, we entered into a commercialization agreement (“Pierre Fabre Commercialization Agreement”) with Pierre Fabre Medicament (“Pierre Fabre”), pursuant to which we granted to Pierre Fabre an exclusive, field-limited license to commercialize and distribute tab-cel in Europe and select emerging markets in the Middle East, Africa, Eastern Europe and Central Asia, following regulatory approval. Atara will retain full rights to tab-cel in other major markets, including North America, Asia Pacific and Latin America. See Note 6 for further information. In December 2020, we entered into a research, development and license agreement (“Bayer License Agreement”) with Bayer AG (“Bayer”) pursuant to which we granted to Bayer an exclusive, field-limited license under the applicable patents and know-how owned or controlled by us and our affiliates covering or related to ATA2271 and ATA3271. In March 2021, as contemplated under the Bayer License Agreement and to further advance our collaboration, we entered into (i) a Manufacturing and Supply Agreement; (ii) a Pharmacovigilance Agreement; (iii) a Quality Agreement; and (iv) a Technology Transfer Agreement (collectively, the Bayer License Agreement, the Manufacturing and Supply Agreement and the Technology Transfer Agreement are referred to as the “Bayer Agreements”). See Note 6 for further information.

We have licensed rights to T-cell product candidates from Memorial Sloan Kettering Cancer Center (“MSK”), rights related to our next-generation CAR T programs from MSK and from H. Lee Moffitt Cancer Center (“Moffitt”), and rights to know-how and technology from the Council of the Queensland Institute of Medical Research (“QIMR Berghofer”). See Note 8 for further information.

In January 2022, we entered into an asset purchase agreement with FUJIFILM Diosynth Biotechnologies California, Inc. (“FDB”) and, for certain limited purposes, FUJIFILM Holdings America Corporation, to sell all of the Company’s right, title and interest in and to certain assets related to the Atara T-Cell Operations and Manufacturing facility (“ATOM Facility”) located in Thousand Oaks, California for $100 million in cash, subject to potential post-closing adjustments pursuant to the asset purchase agreement (the “Fujifilm Transaction”). The closing of the Fujifilm Transaction occurred on April 4, 2022, at which time 136 of our ATOM Facility employees transitioned to FDB as part of the transaction. We also entered into a Master Services and Supply Agreement with FDB (the “Fujifilm MSA”) which became effective upon the closing and could extend for up to ten years. Pursuant to the Fujifilm MSA, FDB will supply us with specified quantities of our cell therapy product candidates and any products approved by regulatory authorities, manufactured in accordance with cGMP standards. See to Note 7 for further information.

2.	Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements include the accounts of Atara and its wholly owned subsidiaries and have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and the requirements of the Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These condensed consolidated financial statements have been prepared on the same basis as the Company’s annual consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021. In the opinion of management, the condensed consolidated financial statements reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair presentation of the Company’s consolidated financial statements. The results of operations for any interim period are not necessarily indicative of the results to be expected for the full year or any other future period. The condensed consolidated balance sheet as of December 31, 2021 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete consolidated financial statements.

Liquidity

We have incurred significant operating losses since inception and have relied primarily on public and private equity financings and receipts from license and collaboration agreements to fund our operations. As we continue to incur losses, our transition to profitability will depend on the successful development, approval and commercialization of product candidates and on the achievement of sufficient revenues to support our cost structure. We may never achieve profitability, and unless and until we do, we will need to continue to raise additional capital. We expect that existing cash, cash equivalents and short-term investments as of March 31, 2022 will be sufficient to fund our planned operations for at least the next twelve months from the date of issuance of these financial statements.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates, assumptions, and judgments that affect the amounts reported in the financial statements and accompanying notes. Significant estimates relied upon in preparing these financial statements include estimates related to revenue recognition, clinical study and other accruals, stock-based compensation expense and income taxes. Actual results could differ materially from those estimates.

Recent Accounting Pronouncements

We consider the applicability and impact of any recent Accounting Standards Update (“ASU”) issued by the Financial Accounting Standards Board (“FASB”). Based on our assessment, the ASUs were determined to be either not applicable or are expected to have minimal impact on our condensed consolidated financial statements.

3.	Net Loss per Common Share

Basic net loss per common share is calculated by dividing net loss by the weighted-average number of shares of common stock and pre-funded warrants outstanding during the period, without consideration of common share equivalents. Diluted net loss per common share is computed by dividing net loss by the weighted-average number of shares of common stock, pre-funded warrants and common share equivalents outstanding for the period. The pre-funded warrants are included in the computation of basic and diluted net loss per common share as the exercise price is negligible and the pre-funded warrants are fully vested and exercisable. Common share equivalents are only included in the calculation of diluted net loss per common share when their effect is dilutive.

Potential dilutive securities, which include unvested restricted stock units (“RSUs”), unvested performance-based RSUs and performance-based options to purchase common stock for which established performance criteria have been achieved as of the end of the respective periods, vested and unvested options to purchase common stock and shares to be issued under our employee stock purchase plan (“ESPP”), have been excluded from the computation of diluted net loss per share as the effect is antidilutive. Therefore, the denominator used to calculate both basic and diluted net loss per common share is the same in all periods presented.

The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted net loss per common share, as their inclusion would have an antidilutive effect:

	As of March 31,
	2022		2021
Unvested RSUs		7,932,532		4,900,248
Vested and unvested options		10,857,620		9,030,928
ESPP share purchase rights		220,029		164,954
Total		19,010,181		14,096,130

4.	Financial Instruments

Our financial assets are measured at fair value on a recurring basis using the following hierarchy to prioritize valuation inputs, in accordance with applicable U.S. GAAP:

Level 1:

Quoted prices in active markets for identical assets or liabilities that we have the ability to access

Level 2:

Observable market-based inputs or unobservable inputs that are corroborated by market data such as quoted prices, interest rates and yield curves

Level 3:

Inputs that are unobservable data points that are not corroborated by market data

We review the fair value hierarchy classification on a quarterly basis. Changes in the ability to observe valuation inputs may result in a reclassification of levels of certain securities within the fair value hierarchy. We recognize transfers into and out of levels within the fair value hierarchy in the period in which the actual event or change in circumstances that caused the transfer occurs. There have been no transfers between Level 1, Level 2 and Level 3 in any periods presented.

Financial assets and liabilities are considered Level 2 when their fair values are determined using inputs that are observable in the market or can be derived principally from or corroborated by observable market data such as pricing for similar securities, recently executed transactions, cash flow models with yield curves, and benchmark securities. In addition, Level 2 financial instruments are valued using comparisons to like-kind financial instruments and models that use readily observable market data as their basis. U.S. Treasury, government agency and corporate debt obligations, commercial paper and asset-backed securities are valued primarily using market prices of comparable securities, bid/ask quotes, interest rate yields and prepayment spreads and are included in Level 2.

Financial assets and liabilities are considered Level 3 when their fair values are determined using pricing models, discounted cash flow methodologies, or similar techniques, and at least one significant model assumption or input is unobservable. We have no Level 3 financial assets or liabilities.

The following tables summarize the estimated fair value and related valuation input hierarchy of our available-for-sale securities as of each period end:

		Total			Total		Total			Total
		Amortized			Unrealized		Unrealized			Estimated
As of March 31, 2022:	Input Level	Cost			Gain		Loss			Fair Value
		(in thousands)
Money market funds	Level 1	$	74,767		$	—	$	—		$	74,767
U.S. Treasury obligations	Level 2		93,764			—		(557	)		93,207
Government agency obligations	Level 2		16,082			—		(107	)		15,975
Corporate debt obligations	Level 2		97,559			—		(1,151	)		96,408
Commercial paper	Level 2		10,881			—		—			10,881
Asset-backed securities	Level 2		8,795			—		(77	)		8,718
Total available-for-sale securities			301,848			—		(1,892	)		299,956
Less: amounts classified as cash equivalents			(99,814	)		—		—			(99,814	)
Amounts classified as short-term investments		$	202,034		$	—	$	(1,892	)	$	200,142

		Total			Total		Total			Total
		Amortized			Unrealized		Unrealized			Estimated
As of December 31, 2021:	Input Level	Cost			Gain		Loss			Fair Value
		(in thousands)
Money market funds	Level 1	$	89,738		$	—	$	—		$	89,738
U.S. Treasury obligations	Level 2		111,832			1