Alto Neuroscience, Inc.

Previous wording

ALTO-207 is a fixed-dose combination of pramipexole, a dopamine D3-preferring D3/D2 agonist, approved for the treatment of Parkinson’s disease with demonstrated antidepressant effect through multiple robust randomized, placebo-controlled clinical trials, and ondansetron, an antiemetic, selective 5-HT3 receptor antagonist. As a fixed-dose combination, ALTO-207 is designed to enable rapid titration and higher dosing by mitigating the dose-limiting adverse events typically experienced with pramipexole. ALTO-207 is being developed to address the significant unmet need for patients with TRD. The Phase 2b trial of ALTO-207, which has the potential to serve as a pivotal trial subject to U.S. Food and Drug Administration, or FDA, feedback and review of data, was initiated in April 2026. The Phase 2b trial is a randomized, double-blind, placebo-controlled study evaluating ALTO-207 as an adjunctive treatment in approximately 178 adults with TRD. Eligible participants will have experienced two to five prior treatment failures and have moderate to severe depression symptoms, and will remain on their baseline antidepressant medication. Participants will be randomized 1:1 to receive ALTO-207 or placebo during an eight-week double-blind treatment period, which includes a 12-day dose titration period to reach a target total daily dose of 3.2mg pramipexole/15mg ondansetron. The study will be conducted across clinical sites in the U.S. and U.K. The primary endpoint is change from baseline in MADRS. The Company expects to report topline data from the trial in the second half of 2027. Following an FDA meeting in October 2025, we also expect to initiate a Phase 3 trial by early 2027 following Phase 3 readiness work and alignment with the FDA on the planned trial design.

Current wording

ALTO-207 is a fixed-dose combination of pramipexole, a dopamine D3-preferring D3/D2 agonist, approved for the treatment of Parkinson’s disease with demonstrated antidepressant effect through multiple robust randomized, placebo-controlled clinical trials, and ondansetron, an antiemetic, selective 5-HT3 receptor antagonist. As a fixed-dose combination, ALTO-207 is designed to enable rapid titration and higher dosing by mitigating the dose-limiting adverse events typically experienced with pramipexole. ALTO-207 is being developed to address the significant unmet need for patients with TRD. The Phase 2b trial of ALTO-207, which has the potential to serve as a pivotal trial subject to U.S. Food and Drug Administration, or FDA, feedback and review of data, was initiated in April 2026. The Phase 2b trial is a randomized, double-blind, placebo-controlled study evaluating ALTO-207 as an adjunctive treatment in approximately 178 adults with TRD. Eligible participants will have experienced two to five prior treatment failures and have moderate to severe depression symptoms, and will remain on their baseline antidepressant medication. Participants will be randomized 1:1 to receive ALTO-207 or placebo during an eight-week double-blind treatment period, which includes a 12-day dose titration period to reach a target total daily dose of 3.2mg pramipexole/15mg ondansetron. The study is being conducted across clinical sites in the U.S. and U.K. The primary endpoint is change from baseline in MADRS. The Company expects to report topline data from the trial in the second half of 2027. We are also on track and expect to initiate an adjunctive TRD Phase 3 trial by early 2027 following Phase 3 readiness work and alignment with the FDA on the planned trial design. In July 2026 we announced plans to further accelerate the development of ALTO-207, and we expect to initiate a monotherapy Phase 3 trial in patients with TRD in the second half of 2027. We believe the broad development program has the potential to position ALTO-207 as a treatment option across the broadest potential TRD patient population.

Previous wording

In May 2025, we acquired ALTO-207 (formerly known as CTC-501) from Chase Therapeutics Corporation, or Chase. Prior to the acquisition, Chase completed a randomized, placebo-controlled Phase 2a clinical trial evaluating CTC-501 in 32 patients with depression. CTC-501 met the primary and secondary endpoints in this trial, demonstrating statistically significant and clinically meaningful improvements on the Montgomery Åsberg Depression Rating Scale, or MADRS, compared to placebo. Patients randomized to receive CTC-501 reached a mean dose of 4.1mg per day. Real-world data demonstrate that it is challenging to achieve doses above 1mg per day of pramipexole. CTC-501 was generally well tolerated in the maintenance period of the study with an adverse event rate similar to placebo.

Current wording

We acquired ALTO-207 (formerly known as CTC-501) from Chase Therapeutics Corporation, or Chase. The scientific rationale for ALTO-207 is supported by the results from multiple independent clinical trials and a Phase 2a clinical trial conducted by Chase prior to our acquisition. In Chase’s randomized, placebo-controlled Phase 2a clinical trial evaluating CTC-501 in 32 patients with depression, CTC-501 met the primary and secondary endpoints, demonstrating statistically significant and clinically meaningful improvements on the Montgomery Åsberg Depression Rating Scale, or MADRS, compared to placebo. Patients randomized to receive CTC-501 reached a mean dose of 4.1mg per day. Real-world data demonstrate that it is challenging to achieve doses above 1mg per day of pramipexole. CTC-501 was generally well tolerated in the maintenance period of the study with an adverse event rate similar to placebo. In the PAX-D study conducted by the University of Oxford. Results, which were published in The Lancet Psychiatry, showed pramipexole augmentation of antidepressant treatment, at a target dose of 2.5mg, demonstrated a large (Cohen’s d=0.87) reduction in symptoms relative to placebo at 12 weeks (and continuing through 48 weeks), but was associated with a high rate of adverse effects.

Previous wording

Our acquisition of ALTO-207 was motivated by the results from the PAX-D study conducted by the University of Oxford. Results, which were published in The Lancet Psychiatry, showed pramipexole augmentation of antidepressant treatment, at a target dose of 2.5mg, demonstrated a large (Cohen’s d=0.87) reduction in symptoms relative to placebo at 12 weeks (and continuing through 48 weeks), but was associated with a high rate of adverse effects. We believe the profile of ALTO-207 will enable higher dosing of pramipexole while mitigating the significant rates of nausea and vomiting that have limited its use for depression.

Current wording

We believe the profile of ALTO-207 will enable higher dosing of pramipexole while mitigating the significant rates of nausea and vomiting that have limited its use for depression.

Previous wording

Following the topline data readout of the Phase 2 proof-of-concept study, further analyses have been completed and the findings reflect a potential product profile suitable for a range of cognitive disorders. Specifically, further analyses identified large and statistically significant effects of ALTO-101 across the overall study population on multiple EEG markers relevant to cognition. ALTO-101 produced an increase in individual alpha peak frequency (d=0.59, p=0.001), a heritable index of neurophysiological efficiency that tracks a range of cognitive functions, as well as a shift toward greater cortical excitability, evidenced by increases in high frequency power (beta: d=0.70, p<0.001; gamma: d=0.61, p=0.001) and a decrease in low frequency power (theta: d=0.50, p=0.007). These changes resulted in a decrease in the theta/beta ratio (d=0.57, p=0.003), an FDA-cleared measure of attention-deficit/hyperactivity disorder. Significant improvement was also observed in sustained attention, as measured by the Continuous Performance Task (d=0.41, p=0.02), while no significant effects were observed in processing speed or memory.

Current wording

(d=0.59, p=0.001), a heritable index of neurophysiological efficiency that tracks a range of cognitive functions, as well as a shift toward greater cortical excitability, evidenced by increases in high frequency power (beta: d=0.70, p<0.001; gamma: d=0.61, p=0.001) and a decrease in low frequency power (theta: d=0.50, p=0.007). These changes resulted in a decrease in the theta/beta ratio (d=0.57, p=0.003), an FDA-cleared measure of attention-deficit/hyperactivity disorder. Significant improvement was also observed in sustained attention, as measured by the Continuous Performance Task (d=0.41, p=0.02), while no significant effects were observed in processing speed or memory.

Previous wording

In June 2025, we announced the completion of our exploratory Phase 2 POC trial of ALTO-203 in MDD with elevated levels of anhedonia and the resulting identification of a patient selection biomarker and positive pharmacodynamic results. The exploratory Phase 2 POC trial, which enrolled 69 patients, was conducted in two sequential, double-blind, placebo-controlled periods. The trial was designed to characterize the pharmacodynamic, pharmacokinetic, safety, and tolerability profile of ALTO-203 across two dose levels compared to placebo in a crossover design and was not powered to detect statistical significance on traditional depression outcome scales (e.g., MADRS).

Current wording

An exploratory Phase 2 POC trial, which enrolled 69 patients, was conducted in two sequential, double-blind, placebo-controlled periods and resulted in the identification of a patient selection biomarker and positive pharmacodynamic results. The trial was designed to characterize the pharmacodynamic, pharmacokinetic, safety, and tolerability profile of ALTO-203 across two dose levels compared to placebo in a crossover design and was not powered to detect statistical significance on traditional depression outcome scales (e.g., MADRS).

Previous wording

Since our inception in 2019, we have devoted substantially all of our resources to the research and development of our product candidates by conducting clinical trials and preclinical studies, building our Platform, and recruiting management and technical staff to support these operations. To date, we have funded our operations primarily through the aggregate net proceeds from equity financings (including from our initial public offering, or IPO, private placement transactions, and pre-IPO sales of our convertible preferred stock) and borrowings under our loan and security agreement.

Current wording

Since our inception in 2019, we have devoted substantially all of our resources to the research and development of our product candidates by conducting clinical trials and preclinical studies, building our Platform, and recruiting management and technical staff to support these opera tions. To date, we have funded our operations primarily through the aggregate net proceeds from equity financings (including from our initial public offering, or IPO, private placement transactions, our July 2026 Offering (see “Liquidity and Capital Resources,” below), and pre-IPO sales of our convertible preferred stock) and borrowings under our loan and security agreement.

Previous wording

We have not generated any revenue from product sales and we have incurred recurring losses since our inception. Our net losses were $26.2 million and $15.2 million for the three months ended March 31, 2026 and 2025, respectively. As of March 31, 2026, we had an accumulated deficit of $227.9 million. We expect to continue to generate operating losses and negative operating cash flows for the foreseeable future. We anticipate that our operating expenses and capital expenditures will increase substantially with our ongoing activities, particularly as we:

Current wording

We have not generated any revenue from product sales and we have incurred recurring losses since our inception. Our net losses were $27.6 million and $53.9 million for the three and six months ended June 30, 2026, respectively. Our net losses were $17.7 million and $32.9 million for thethree and six months ended June 30, 2025, respectively. As of June 30, 2026, we had an accumulated deficit of $255.5 million. We expect to continue to generate operating losses and negative operating cash flows for the foreseeable future. We anticipate that our operating expenses and capital expenditures will increase substantially with our ongoing activities, particularly as we:

Previous wording

•continue to progress the clinical development of our product candidates, including ALTO-207 in our Phase 2b clinical trial and planned Phase 3 clinical trial, and ALTO-100 and ALTO-300 in ongoing Phase 2b clinical trials, as well as ALTO-203, and ALTO-208;

Current wording

•continue to progress the clinical development of our product candidates, including ALTO-207 in our Phase 2b clinical trial and planned Phase 3 clinical trials, and ALTO-100 and ALTO-300 in ongoing Phase 2b clinical trials, as well as ALTO-203, and ALTO-208;

Previous wording

As of March 31, 2026, we had cash, cash equivalents and restricted cash of$264.3 million. We believe that our existing cash and cash equivalents, together with the anticipated proceeds under our Convertible Grant Agreement with Wellcome, will be sufficient to fund our operating expenses and capital expenditure requirements for at least the next 12 months. See “—Liquidity and Capital Resources.”

Current wording

As of June 30, 2026, we had cash, cash equival ents and restricted cash of $244.2 million, and we raised approximately $94.6 million in July 2026 Offering (defined below). We believe that our existing cash and cash equivalents, together with the net proceeds of the July 2026 Offering and the anticipated proceeds under our Convertible Grant Agreement with Wellcome, will be sufficient to fund our operating expenses and capital expenditure requirements for at least the next 12 months. See “—Liquidity and Capital Resources.”

Previous wording

Research and development expenses were $20.3 million for the three months ended March 31, 2026, compared to $10.0 million for the three months ended March 31, 2025. Increases in research and development expenses were due primarily to:

Current wording

Research and development expenses were $22.1 million for the three months ended June 30, 2026, compared to $13.1 million for the three months ended June 30, 2025. Increases in research and development expenses were due primarily to:

Previous wording

•an increase of approximately $4.1 million in expenses related to development of our ALTO-207 program, which we acquired in May 2025. The costs primarily related to clinical and manufacturing activities required to launch the Phase 2b clinical trial, which we announced the initiation of in April 2026.

Current wording

•an increase of approximately $6.4 million in expenses related to development of our ALTO-207 program, whichwe acquired in May 2025. The costs are primarily related to clinical and manufacturing activities required to launch the Phase 2b clinical trial, which we initiated in April 2026.

Previous wording

•an increase of approximately $4.4 million in expenses related to the development of our ALTO-101 program, including our Phase 2 POC trial of ALTO-101 for which we announced top line data on April 1, 2026.

Current wording

•an increase of approximately $1.0 million in expenses related to the development of our ALTO-101 program, including our Phase 2 POC trial of ALTO-101 for which we announced top line data on April 1, 2026.

Previous wording

•an increase of $1.2 million in salary and personnel related costs, which includes $0.5 million of non-cash stock-based compensation.

Current wording

•an increase of $1.4 million in salary and personnel related costs, which includes $0.9 million of increased non-cash stock-based compensation.

Previous wording

General and administrative expenses were $6.8 million for the three months ended March 31, 2026, compared to $5.7 million for the three months ended March 31, 2025. The increase of $1.1 million was primarily due to increases in professional fees.

Current wording

General and administrative expenses were $7.0 million for the three months ended June 30, 2026, compared to $5.6 million for the three months ended June 30, 2025. The increase of $1.5 million was primarily due to increases in professional fees.

Previous wording

Other income, net increased $0.4 million during the three months ended March 31, 2026, compared to the three months ended March 31, 2025. The increase was primarily due to debt extinguishment costs of $0.7 million that were incurred during the three months ended March 31, 2025. This increase was partially offset by a decrease in interest income of $0.3 million during the three months ended March 31, 2026 compared to the three months ended March 31, 2025.

Current wording

Other income, net increased $0.5 million during the three months ended June 30, 2026, compared to the three months ended June 30, 2025. The increase was primarily due to the increase in interest income of $0.4 million during the three months ended June 30,2026 compared to the three months ended June 30, 2025.

Previous wording

We have incurred net losses and negative cash flows from operations since our inception and anticipate we will continue to incur net losses for the foreseeable future. We have not yet commercialized any of our product candidates, which are in various phases of development, and we do not expect to generate revenue from sales of any of our product candidates for several years, if at all. As we progress through the phases of development, we anticipate that we will incur increasing losses in future quarters and years compared to historical periods. To date, we have funded our operations primarily through the aggregate net proceeds from equity financings (including from our IPO, our October 2025 and March 2026 private placement transactions, and pre-IPO sales of our convertible preferred stock) and borrowings under our loan and security agreement.

Current wording

We have incurred net losses and negative cash flows from operations since our inception and anticipate we will continue to incur net losses for the foreseeable future. We have not yet commercialized any of our product candidates, which are in various phases of development, and we do not expect to generate revenue from sales of any of our product candidates for several years, if at all. As we progress through the phases of development, we anticipate that we will incur increasing losses in future quarters and years compared to historical periods. To date, we have funded our operations primarily through the aggregate net proceeds from equity financings (including from our IPO, our October 2025 and March 2026 private placement transactions (described below), our July 2026 Offering, and pre-IPO sales of our convertible preferred stock) and borrowings under our loan and security agreement.

Previous wording

As of March 31, 2026 and December 31, 2025, we had cash, cash equivalents and restricted cash of $264.3 million and $177.0 million, respectively.

Current wording

As of June 30, 2026 and December 31, 2025, we had cash, cash equivalents and restricted cash of $244.2 million and $177.0 million, respectively.

Previous wording

In October 2025, we entered into a Securities Purchase Agreement, or the 2025 PIPE Purchase Agreement, with certain institutional and other accredited investors, or the 2025 PIPE Purchasers, pursuant to which we sold and issued to the 2025 PIPE Purchasers in a private placement transaction, or the 2025 Private Placement: (i) 3,832,263 shares of our common stock, or the 2025 PIPE Shares and (ii) with respect to certain 2025 PIPE Purchasers, pre-funded warrants to purchase 4,622,251 shares of our common stock, or the 2025 Pre-Funded Warrants, in lieu of shares of common stock. The purchase price per share of common stock was $5.9140 per share, or the 2025 PIPE Purchase Price, and the purchase price for the 2025 Pre-Funded Warrants was $5.9139 per 2025 Pre-Funded Warrant. The closing occurred on October 21, 2025. The total gross proceeds to us were approximately $50.0 million, and, after deducting offering expenses payable by us, net proceeds were approximately $49.7 million.

Current wording

In October 2025, we entered into a Securities Purchase Agreement, or the 2025 PIPE Purchase Agreement, with certain institutional or other accredited investors, or the 2025 PIPE Purchasers, pursuant to which we sold and issued to the 2025 PIPE Purchasers in a private placement transaction, or the 2025 Private Placement: (i) 3,832,263 shares of our common stock, or the 2025 PIPE Shares, and (ii) with respect to certain 2025 PIPE Purchasers, pre-funded warrants to purchase 4,622,251 shares of our common stock, or the 2025 Pre-Funded Warrants, in lieu of shares of common stock. The purchase price per share of common stock was $5.9140 per share, or the 2025 PIPE Purchase Price, and the purchase price for the 2025 Pre-Funded Warrants was $5.9139 per 2025 Pre-Funded Warrant. The closing occurred on October 21, 2025. The total gross proceeds to us were approximately $50.0 million, and, after deducting offering expenses payable by us, net proceeds were approximately $49.7 million.

Previous wording

In March 2026, we entered into a Securities Purchase Agreement, or the 2026 PIPE Purchase Agreement, with certain institutional investors, or the 2026 PIPE Purchasers, pursuant to which we sold and issued to the 2026 PIPE Purchasers in a private placement transaction, or 2026 Private Placement: (i) 2,900,000 shares of our common stock, or the 2026 PIPE Shares and (ii) with respect to certain 2026 PIPE Purchasers, pre-funded warrants to purchase 3,100,000 shares of our common stock, or the 2026 Pre-Funded Warrants, in lieu of shares of common stock. The purchase price per share of common stock was $20.00 per share, or the 2026 PIPE Purchase Price, and the purchase price for the 2026 Pre-Funded Warrants was $19.9999 per 2026 Pre-Funded Warrant. The closing occurred on March 17, 2026. The total gross proceeds to us were approximately $120.0 million, and, after deducting offering expenses payable by us, net proceeds were approximately $114.9 million.

Current wording

In March 2026, we entered into a Securities Purchase Agreement, or the 2026 PIPE Purchase Agreement, with certain institutional investors, or the 2026 PIPE Purchasers, pursuant to which we sold and issued to the 2026 PIPE Purchasers in a private placement transaction, or 2026 Private Placement: (i) 2,900,000 shares of our common stock, or the 2026 PIPE Shares, and (ii) with respect to certain 2026 PIPE Purchasers, pre-funded warrants to purchase 3,100,000 shares of our common stock, or the 2026 Pre-Funded Warrants, in lieu of shares of common stock. The purchase price per share of common stock was $20.00 per share, or the 2026 PIPE Purchase Price, and the purchase price for the 2026 Pre-Funded Warrants was $19.9999 per 2026 Pre-Funded Warrant. The closing occurred on March 17, 2026. The total gross proceeds to us were approximately $120.0 million, and, after deducting offering expenses payable by us, net proceeds were approximately $114.8 million.

Previous wording

Beginning January 1, 2026, we must maintain, at all times, a cash runway of at least five months based upon a trailing three month cash consumption calculation, provided that this covenant will be waived during any period in which our market capitalization exceeds $700.0 million. The Term Loan is secured by substantially all of our assets, excluding intellectual property.

Current wording

We must maintain, at all times, a cash runway of at least five months based upon a trailing three month cash consumption calculation, provided that this covenant is waived during any period in which our market capitalization exceeds $700.0 million. The Term Loan is secured by substantially all of our assets, excluding intellectual property.

Previous wording

We may use proceeds from the Convertible Loan solely to advance development of ALTO-100 in bipolar depression. In addition, if we do not exploit or develop ALTO-100 (other than for safety or efficacy concerns) within a specified period following the completion of our Phase 2b clinical trial evaluating ALTO-100 in patients with bipolar depression, the Convertible Grant Agreement provides Wellcome with a limited right to exploit ALTO-100, solely in bipolar depression, subject to a revenue share between Wellcome and us of any proceeds arising from Wellcome’s exploitation. Outstanding amounts under the Convertible Loan accrue interest at an annual rate equal to the Sterling Overnight Index Rate plus 2%, subject to potential adjustment if such interest rate equals or exceeds 9% at any time. At any time after the second anniversary of the effective date of the Convertible Grant Agreement or in connection with an event of default, Wellcome has the right, at its election, to convert some or all of the Convertible Loan into shares of our common stock at a price per share equal to a 20% discount to the thirty-day volume-weighted average price of Common Stock on the New York Stock Exchange at the date of such conversion. The Convertible Grant Agreement provides that in no event shall the aggregate number of shares of our common stock issued pursuant to conversion of the Convertible Loan exceed 5,363,326, which is equal to 19.9% of the number of shares of our common stock outstanding as of the date of the Convertible Grant Agreement. At any time after the fifth anniversary of the date of the Convertible Grant Agreement or in connection with an event of default, Wellcome may require repayment of the Convertible Loan in full, together with accrued interest, to the extent not converted as described above.

Current wording

Convertible Grant Agreement provides Wellcome with a limited right to exploit ALTO-100, solely in bipolar depression, subject to a revenue share between Wellcome and us of any proceeds arising from Wellcome’s exploitation. Outstanding amounts under the Convertible Loan accrue interest at an annual rate equal to the Sterling Overnight Index Rate plus 2%, subject to potential adjustment if such interest rate equals or exceeds 9% at any time. At any time after the second anniversary of the effective date of the Convertible Grant Agreement or in connection with an event of default, Wellcome has the right, at its election, to convert some or all of the Convertible Loan into shares of our common stock at a price per share equal to a 20% discount to the thirty-day volume-weighted average price of Common Stock on the New York Stock Exchange at the date of such conversion. The Convertible Grant Agreement provides that in no event shall the aggregate number of shares of our common stock issued pursuant to conversion of the Convertible Loan exceed 5,363,326, which is equal to 19.9% of the number of shares of our common stock outstanding as of the date of the Convertible Grant Agreement. At any time after the fifth anniversary of the date of the Convertible Grant Agreement or in connection with an event of default, Wellcome may require repayment of the Convertible Loan in full, together with accrued interest, to the extent not converted as described above.

Previous wording

On February 3, 2025, we filed a shelf registration statement on Form S-3 with the SEC in relation to the registration of common stock, preferred stock, debt securities, warrants and units or any combination thereof up to a total aggregate offering price of $300.0 million.

Current wording

On February 3, 2025, we filed a shelf registration statement on Form S-3 with the SEC in relation to the registration of common stock, preferred stock, debt securities, warrants and units or any combination thereof up to a total aggregate offering price of $300.0 million. We issued and sold $100.0 million of shares of our common stock pursuant to the shelf registration statement in the July 2026 Offering.

Previous wording

On February 3, 2025, we also simultaneously entered into a Sales Agreement, or the Sales Agreement, with Leerink Partners LLC, or the Sales Agent, pursuant to which we could issue and sell, from time to time at our discretion, shares of our common stock having an aggregate offering price of up to $75.0 million through or to the Sales Agent. We terminated the Sales Agreement effective as of October 30, 2025. We had not sold any shares of common stock under the Sales Agreement prior to termination.

Current wording

On February 3, 2025, we entered into a Sales Agreement, or the Sales Agreement, with Leerink Partners LLC, or the Sales Agent, pursuant to which we could issue and sell, from time to time at our discretion, shares of our common stock having an aggregate offering price of up to $75.0 million through or to the Sales Agent. We terminated the Sales Agreement effective as of October 30, 2025. We had not sold any shares of common stock under the Sales Agreement prior to termination.

Previous wording

Net cash used in operating activities was$27.1 million for the three months ended March 31, 2026, as compared to $16.6 million for the three months ended March 31, 2025. The increase in cash used was the result of an increase in net losses of $11.1 million which was partially offset by increased non-cash stock-based compensation expenses of $0.9 million.

Current wording

Net cash used in operating activities was$46.9 million for the six months ended June 30, 2026, as compared to $30.3 million for the six months ended June 30, 2025. The increase in cash used was the result of an increase in net losses of $21.0 million which was partially offset by increased non-cash stock-based compensation expenses of $2.4 million.

Previous wording

Net cash used in investing activities consisted of purchases of property and equipment that are being used for research and development purposes.

Current wording

Net cash used in investing activities six months ended June 30, 2026 consisted of purchases of property and equipment that are being used for research and development purposes.

Previous wording

The net cash used in investing activities for the three months ended March 31, 2025 was negligible.

Current wording

The net cash used in investing activities for the six months ended June 30, 2025 was negligible.

Previous wording

Net cash provided by financing activities was $114.9 million for the three months ended March 31, 2026, primarily related to the proceeds from our 2026 PIPE Purchase Agreement.

Current wording

Net cash provided by financing activities was $114.7 million for the six months ended June 30, 2026, primarily related to the proceeds from our 2026 PIPE Purchase Agreement.

Previous wording

Net cash provided by financing activities was$9.1 million for thethree months ended March 31, 2025, primarily related to borrowings under our Amended Loan Agreement, offset by the repayment of our original loan and related financing obligations and lender fees.

Current wording

Net cash provided by financing activities was$9.7 million for thesix months ended June 30, 2025, primarily related to borrowings under our Amended Loan Agreement as well as the drawdown of$0.8 million under our Convertible Grant Agreement.

Previous wording

We believe that our existing cash and cash equivalents of $263.8 million as of March 31, 2026, together with the anticipated proceeds under our Convertible Grant Agreement with Wellcome, will be sufficient to fund our operating expenses and capital expenditure requirements for at least the next 12 months. However, our forecast of the period of time through which our financial resources will be adequate to support our operations is a forward-looking statement that involves risks and uncertainties, and actual results could vary materially. We have based this estimate on assumptions that may prove to be wrong, and we could expend our capital resources sooner than we currently expect.

Current wording

We believe that our existing cash and cash equivalents of $243.7 million as of June 30, 2026, together with both the net proceeds of approximately $94.6 million from the July 2026 Offering and the anticipated proceeds under our Convertible Grant Agreement with Wellcome, will be sufficient to fund our operating expenses and capital expenditure requirements for at least the next 12 months. However, our forecast of the period of time through which our financial resources will be adequate to support our operations is a forward-looking statement that involves risks and uncertainties, and actual results could vary materially. We have based this estimate on assumptions that may prove to be wrong, and we could expend our capital resources sooner than we currently expect.

Previous wording

In addition to ongoing needs to fund our operations, our material cash requirements as of March 31, 2026 consist primarily of obligations under both our Amended Loan Agreement (see Note 4 to our unaudited condensed consolidated financial statements included elsewhere in this Quarterly Report) and our lease commitment for our headquarters office space located in Mountain View, California with an initial lease term of 65 months that terminates in March 2030 for which we currently have a $5.9 million commitment remaining. If the Company elects to terminate the lease after the third lease year, including payments already made, the Company will make payments of approximately $4.0 million over the term of the lease.

Current wording

In addition to ongoing needs to fund our operations, our material cash requirements as of June 30, 2026 consist primarily of obligations under both our Amended Loan Agreement (see Note 4 to our unaudited condensed consolidated financial statements included elsewhere in this Quarterly Report) and our lease commitment for our headquarters office space located in Mountain View, California with an initial lease term of 65 months that terminates in March 2030 for which we currently have a $5.6 million commitment remaining. If the Company elects to terminate the lease after the third lease year, including payments already made, the Company will make payments of approximately $4.0 million over the term of the lease.

Previous wording

On May 31, 2025, we entered into an asset purchase agreement, or Chase Agreement, with Chase Therapeutics Corporation, or Chase, to acquire all patent, know-how and other rights to ALTO-207, ALTO-208, and certain related assets.

Current wording

On May 31, 2025, we entered into an asset purchase agreement, or Chase Agreement, with Chase Therapeutics Corporation, or Chase, to acquire all patent, know-how and other rights to ALTO-207, ALTO-208, and certain related assets. In May 2026, we achieved aclinical milestone under the Chase Agreement related to the initiation of our Phase 2b clinical trial evaluating ALTO-207 and paid $2.0 million to Chase during the three and six months ended June 30, 2026.

Previous wording

We could not estimate when milestones, royalties, and/or other payments due to third parties under our existing license agreements will be due, and none of these events were probable to occur as of March 31, 2026.

Current wording

Other than as described above, we could not estimate when milestones, royalties, and/or other payments due to third parties under our existing license agreements will be due, and none of these events were probable to occur as of June 30, 2026.

Previous wording

We are also a “smaller reporting company” as defined in the Securities Exchange Act of 1934, as amended, or the Exchange Act. We may continue to be a smaller reporting company even after we are no longer an emerging growth company. We may take advantage of certain of the scaled disclosures available to smaller reporting companies and will be able to take advantage of these scaled disclosures for so long as our voting and non-voting common stock held by non-affiliates is less than $250.0 million measured on the last business day of our second fiscal quarter, or our annual revenue is less than $100.0 million during the most recently completed fiscal year and our voting and non-voting common stock held by non-affiliates is less than $700.0 million measured on the last business day of our second fiscal quarter.

Current wording

We are eligible to use the requirements of a “smaller reporting company” as defined in the Securities Exchange Act of 1934, as amended, or the Exchange Act. We may take advantage of certain of the scaled disclosures available to smaller reporting companies and will be able to take advantage of these scaled disclosures for so long as our voting and non-voting common stock held by non-affiliates is less than $250.0 million measured on the last business day of our second fiscal quarter (or the scaled disclosure accommodations otherwise remain available), or our annual revenue is less than $100.0 million during the most recently completed fiscal year and our voting and non-voting common stock held by non-affiliates is less than $700.0 million measured on the last business day of our second fiscal quarter.