Atara Biotherapeutics, Inc.

Previous wording

We have executed various strategic reductions in force over the past several years. As of March 31, 2026 and December 31, 2025, we had approximately $0.1 million and $0.9 million, respectively, of further separation payments and benefits required for these reductions in force. In the three months ended March 31, 2026 expenses related to reductions in force were $0. In the three months ended March 31, 2025 expenses related to reductions in force were approximately $9.8 million.

Current wording

We have executed various strategic reductions in force over the past several years. As of June 30, 2026 and December 31, 2025, we had approximately $0.8 million and $0.9 million, respectively, of further separation payments and benefits required for these reductions in force. In the three and six months ended June 30, 2026 expenses related to reductions in force were $0.8 million, for each period. In the three and six months ended June 30, 2025 expenses related to reductions in force were approximately $1.5 million and $11.3 million, respectively.

Previous wording

Our net income (loss) was ($4.1) million and $38.0 million for the three months ended March 31, 2026 and 2025, respectively. As of March 31, 2026, we had an accumulated deficit of $2.0 billion. Substantially all of our net losses have resulted from costs incurred in connection with our research and development programs and from general and administrative expenses associated with our operations. As of March 31, 2026, our cash, cash equivalents and short-term investments totaled $8.4 million, which we intend to use to fund our operations.

Current wording

Our net income (loss) was ($9.0) million and $40.4 million for the six months ended June 30, 2026 and 2025, respectively. As of June 30, 2026, we had an accumulated deficit of $2.0 billion. Substantially all of our net losses have resulted from costs incurred in connection with our research and development programs and from general and administrative expenses associated with our operations. As of June 30, 2026, our cash, cash equivalents and short-term investments totaled $9.9 million, which we intend to use to fund our operations.

Previous wording

The largest component of our total operating expenses since inception has been our investment in research and development activities, including the preclinical and clinical development of our product candidates. Research and development expenses consist primarily of compensation and benefits for research and development and regulatory support employees, including stock-based compensation; expenses incurred under agreements with contract research organizations and investigative sites that conduct preclinical and clinical studies; the costs of acquiring and manufacturing clinical study materials and other supplies, including expenses incurred under agreements with CMOs; payments under licensing and research and development agreements; other outside services and consulting costs; and facilities, information technology and overhead expenses. Research and development costs are expensed as incurred.

Current wording

Research and development expenses consist primarily of compensation and benefits for research and development and regulatory support employees, including stock-based compensation; expenses incurred under agreements with contract research organizations and investigative sites that conduct preclinical and clinical studies; the costs of acquiring and manufacturing clinical study materials and other supplies, including expenses incurred under agreements with CMOs; payments under licensing and research and development agreements; other outside services and consulting costs; and facilities, information technology and overhead expenses. Research and development costs are expensed as incurred.

Previous wording

There have been no significant changes to our critical accounting policies and significant judgments and estimates during the three months ended March 31, 2026 from those disclosed in our management’s discussion and analysis of financial condition and results of operations included in our Annual Report on Form 10-K for the year ended December 31, 2025 filed with the SEC on March 16, 2026.

Current wording

There have been no significant changes to our critical accounting policies and significant judgments and estimates during the six months ended June 30, 2026 from those disclosed in our management’s discussion and analysis of financial condition and results of operations included in our Annual Report on Form 10-K for the year ended December 31, 2025 filed with the SEC on March 16, 2026.

Previous wording

Comparison of the Three Months Ended March 31, 2026 and 2025

Current wording

Comparison of the Three and Six Months Ended June 30, 2026 and 2025

Previous wording

Commercialization revenues were $0.5 million for the three months ended March 31, 2026 as compared to $98.1 million in the comparative 2025 period. The revenue in the prior-year period reflects the transfer of tab‑cel manufacturing responsibilities to Pierre Fabre on March 31, 2025, which resulted in a one‑time acceleration of revenue recognized upon satisfaction of substantially all commercialization and transition‑related performance obligations. In the current period, commercialization revenues relate solely to ongoing regulatory activities, resulting in significantly lower revenue recognized during the three months ended March 31, 2026.

Current wording

Commercialization revenues were $0.6 million and $1.1 million for the three and six months ended June 30, 2026 as compared to $17.6 million and $115.7 million in the comparative 2025 period. The revenue in the prior-year period reflects the transfer of tab‑cel manufacturing responsibilities to Pierre Fabre on March 31, 2025, which resulted in a one‑time acceleration of revenue recognized upon satisfaction of substantially all commercialization and transition‑related performance obligations. In the current period, commercialization revenues relate solely to ongoing regulatory activities and clinical vial sales, resulting in significantly lower revenue recognized during the three and six months ended June 30, 2026.

Previous wording

Cost of commercialization revenue was $0.1 million for the three months ended March 31, 2026, as compared to $20.4 million in the comparative 2025 period. The decrease in the 2026 period is primarily due to the recognition of deferred cost of commercialization revenue in the prior-year period upon the transfer of manufacturing responsibilities to Pierre Fabre on March 31, 2025.

Current wording

Cost of commercialization revenue was $0.2 million and $0.3 million for the three and six months ended June 30, 2026, as compared to $0.6 million and $21.0 million in the comparative 2025 periods. The decrease in the 2026 period is primarily due to the recognition of deferred cost of commercialization revenue in the prior-year period upon the transfer of manufacturing responsibilities to Pierre Fabre on March 31, 2025.

Previous wording

Technical operations and quality expenses were $1.0 million in the three months ended March 31, 2026, as compared to $19.3 million in the comparative 2025 period. The decrease in 2026 was primarily due to the transition of tab-cel manufacturing activities to Pierre Fabre as of March 31, 2025 and reduced headcount following the 2025 reductions in force.

Current wording

Technical operations and quality expenses were $0.9 million and $2.0 million in the three and six months ended June 30, 2026, as compared to $2.5 million and $21.8 million in the comparative 2025 periods. The decrease in 2026 was primarily due to the transition of tab-cel manufacturing activities to Pierre Fabre as of March 31, 2025 and reduced headcount following the 2025 reductions in force.

Previous wording

In the three months ended March 31, 2026 medical and safety expenses were approximately ($1.3) million, which reflects a change in estimate of final clinical related costs upon agreement being reached in this period. In the three months ended March 31, 2025 medical and safety expenses totaled $5.3 million. The decrease in 2026 was primarily due to reduced headcount following the 2025 reductions in force, transition of tab-cel clinical trials to Pierre Fabre in July 2025, and termination of the ATA3219 phase 1 trials after decision to pause research and development for CAR T assets in March 2025.

Current wording

Medical and safety expenses were $0.1 million and ($1.2) million in the three and six months ended June 30, 2026, as compared to $3.6 million and $9.0 million in the comparative 2025 periods. The decrease in 2026 was primarily due to reduced headcount following the 2025 reductions in force, transition of tab-cel clinical trials to Pierre Fabre in July 2025, and termination of the ATA3219 phase 1 trials after decision to pause research and development for CAR T assets in March 2025. The decrease in the six month period was also due to a change in estimate of final clinical related costs upon agreement being reached as of March 31, 2026.

Previous wording

General and administrative expenses were $3.6 million in the three months ended March 31, 2026, as compared to $11.5 million in the respective comparative 2025 period. The decrease in 2026 was primarily due to reduced headcount following the 2025 reductions in force and lower general and administrative expenses.

Current wording

General and administrative expenses were $3.8 million and $7.4 million in the three and six months ended June 30, 2026, as compared to $6.5 million and $18.0 million in the respective comparative 2025 periods. The decrease in 2026 was primarily due to reduced headcount following the 2025 reductions in force and lower general and administrative expenses.

Previous wording

Interest income was $54,000 in the three months ended March 31, 2026, as compared to $0.2 million in the comparative 2025 period. The decrease in the 2026 period was primarily due to lower average balances of cash, cash equivalents and available-for-sale securities.

Current wording

Interest income was $0.1 million and $0.1 million in the three and six months ended June 30, 2026, as compared to $0.1 million and $0.4 million in the comparative 2025 periods. The decrease in the 2026 period was primarily due to lower average balances of cash, cash equivalents and available-for-sale securities.

Previous wording

In the past five years, we have entered into two separate sales agreements with Cowen and Company, LLC (Cowen): in November 2021 (2021 ATM Facility) and in November 2023 (2023 ATM Facility). Each ATM facility provides or provided for the sale, in our sole discretion, of shares of our common stock having an aggregate offering price of up to $100.0 million, through Cowen, as our sales agent. We filed a registration statement on Form S-3 registering the offer and sale of these shares under the Securities Act (2023 Registration Statement). Upon the effectiveness of the 2023 Registration Statement, the 2021 ATM Facility was terminated, and no further sales can be made under the 2021 ATM Facility. The issuance and sale of these shares by us pursuant to the ATM facilities are deemed “at the market” offerings defined in Rule 415 under the Securities Act of 1933, as amended (Securities Act), and were registered under the Securities Act. Commissions of up to 3.0% are due on the gross sales proceeds of the common stock sold under each ATM facility.

Current wording

We entered into a sales agreement with Cowen and Company, LLC (Cowen) in November 2023 (2023 ATM Facility). The ATM facility provides or provided for the sale, in our sole discretion, of shares of our common stock having an aggregate offering price of up to $100.0 million, through Cowen, as our sales agent. We filed a registration statement on Form S-3 registering the offer and sale of these shares under the Securities Act (2023 Registration Statement). The issuance and sale of these shares by us pursuant to the ATM facility are deemed “at the market” offerings defined in Rule 415 under the Securities Act of 1933, as amended (Securities Act), and were registered under the Securities Act. Commissions of up to 3.0% are due on the gross sales proceeds of the common stock sold under the ATM facility.

Previous wording

During the three months ended March 31, 2026, we sold an aggregate of 493,117 shares of common stock under the 2023 ATM Facility, at an average price of $6.08 per share, for gross proceeds of $3.0 million and net proceeds of $2.9 million, after deducting commissions and other offering expenses payable by us.

Current wording

During the six months ended June 30, 2026, we sold an aggregate of 991,017 shares of common stock under the 2023 ATM Facility, at an average price of $7.97 per share, for gross proceeds of $7.9 million and net proceeds of $7.7 million, after deducting commissions and other offering expenses payable by us.

Previous wording

As of March 31, 2026, we had $84.2 million of common stock remaining and available to be sold under the 2023 ATM Facility. Subsequent to March 31, 2026, we sold an aggregate of 497,900 shares of our common stock under the 2023 ATM Facility at an average price of $9.84 per share, for net proceeds of $4.8 million, after deducting commission expenses payable by us.

Current wording

As of June 30, 2026, $79.3 million of common stock remained available to be sold under the 2023 ATM Facility.

Previous wording

As of the date of the filing of our Annual Report on Form 10-K for the year ended December 31, 2025, our public float was less than $75 million. As a result, we are subject to the limitations of General Instruction I.B.6 to Form S-3 until such time as our public float exceeds $75 million, which means we only have the capacity to sell shares up to one-third of our public float under shelf registration statements in any twelve-month period. We will remain constrained by the limitations of General Instruction I.B.6 to Form S-3 until such time as our public float exceeds $75 million, at which time the number of securities we may sell under a Form S-3 registration statement will no longer be limited by limitations of General Instruction I.B.6 to FormS-3. Consistent with a recent SEC Corporation Finance Interpretation, the limitations of General Instruction I.B.6 of Form S-3 do not apply to the 2023 ATM Facility.

Current wording

As of the date of the filing of our Annual Report on Form 10-K for the year ended December 31, 2025, our public float was less than $75 million. As a result, we are subject to the limitations of General Instruction I.B.6 to Form S-3 until such time as our public float exceeds $75 million, which means we only have the capacity to sell shares up to one-third of our public float under shelf registration statements in any twelve-month period. We will remain constrained by the limitations of General Instruction I.B.6 to Form S-3 until such time as our public float exceeds $75 million, at which time the number of securities we may sell under a Form S-3 registration statement will no longer be limited by limitations of General Instruction I.B.6 to Form S-3. Consistent with a recent SEC Corporation Finance Interpretation, the limitations of General Instruction I.B.6 of Form S-3 do not apply to the 2023 ATM Facility under our existing shelf registration statement on Form S-3. Further, our existing shelf registration statement on Form S-3 expires on November 11, 2026. If our public float remains below $75 million, any new or replacement registration statement on Form S-3 that we file will be subject to General Instruction I.B.6, which would limit the aggregate amount we may sell in primary offerings under that registration, including pursuant to the 2023 ATM Facility, in any 12-month period to one-third of our public float.

Previous wording

Our cash and cash equivalents totaled $8.4 million and $8.5 million as of March 31, 2026 and December 31, 2025, respectively.

Current wording

Our cash, cash equivalents and short-term investments totaled $9.9 million and $8.5 million as of June 30, 2026 and December 31, 2025, respectively.

Previous wording

Net cash used in operating activities was $3.1 million in the three months ended March 31, 2026 as compared to $28.1 million in the comparative 2025 period. The decrease of $25.0 million was primarily due to lower compensation-related costs resulting from lower headcount driven by the 2025 reductions in force, as well as transition of tab-cel clinical trials and manufacturing activities to Pierre Fabre in 2025.

Current wording

Net cash used in operating activities was $6.4 million in the six months ended June 30, 2026 as compared to $35.5 million in the comparative 2025 period. The decrease of $29.1 million was primarily due to lower compensation-related costs resulting from lower headcount driven by the 2025 reductions in force, as well as transition of tab-cel clinical trials and manufacturing activities to Pierre Fabre in 2025.

Previous wording

Net cash provided by investing activities in the three months ended March 31, 2026 was $0 as compared to $17.2 million in the comparative 2025 period, primarily reflecting proceeds from maturities and sales of available-for-sale securities.

Current wording

Net cash used in investing activities in the six months ended June 30, 2026 was $6.6 million, primarily reflecting purchases of short-term investments with no offsetting maturities, as compared to net cash provided by investing activities of $12.1 million in the comparative 2025 period, which primarily reflected proceeds from maturities and sales of available-for-sale securities.

Previous wording

Net cash provided by financing activities in the three months ended March 31, 2026 consisted of $3.0 million of net proceeds received from the 2023 ATM Facility. Net cash used in financing activities in the comparative 2025 period primarily consisted of $0.3 million in principal payments on finance lease obligations.

Current wording

Net cash provided by financing activities in the six months ended June 30, 2026 consisted of $7.8 million of net proceeds received from the 2023 ATM Facility. Net cash provided by financing activities in the six months ended June 30, 2025 primarily consisted of $15.3 million in proceeds from the issuance of pre-funded warrants and shares in an underwritten registered direct offering, net of discount.