Alto Neuroscience Expands ALTO-207 Phase 3 Program in Treatment-Resistant Depression, Backed by $100 Million Financing
核心洞察
Alto Neuroscience reported a second-quarter 2026 net loss of $27.6 million and added a Phase 3 monotherapy trial of ALTO-207 (搜索) in treatment-resistant depression (搜索) (TRD).
An independent Nature Medicine publication of the PRIME-PRAXOL trial showed pramipexole significantly reduced anhedonia versus placebo (SHAPS mean difference −4.04; p=0.006).
A July 2026 offering raised approximately $100 million in gross proceeds, bringing pro forma cash to roughly $338 million and extending runway through 2030.
Alto Neuroscience, Inc. (NYSE: ANRO), a clinical-stage biopharmaceutical company focused on precision medicines for neuropsychiatric disorders, reported second-quarter 2026 financial results and announced an expansion of its late-stage development program for ALTO-207 (搜索) in treatment-resistant depression (搜索) (TRD). The company added a planned Phase 3 monotherapy trial to its development plan, supported by a roughly $100 million financing completed in July 2026 and independent data published in Nature Medicine reinforcing the drug's dopaminergic mechanism.
"With enrollment in our potentially registrational Phase 2b trial tracking as planned and pro forma cash of approximately $338 million, we are now positioned to pursue ALTO-207 (搜索) in both the adjunctive and monotherapy settings, broadening the potential label and the commercial opportunity, with expected runway through 2030," said Amit Etkin, M.D., Ph.D., founder and chief executive officer of Alto Neuroscience.
Independent Evidence Reinforces Dopaminergic Mechanism
ALTO-207 (搜索) is a fixed-dose combination of pramipexole, a dopamine D3-preferring D3/D2 agonist with demonstrated antidepressant effect across multiple independent trials, and ondansetron, a selective 5-HT3 receptor (搜索) antagonist. The fixed-dose combination is designed to enable rapid titration to higher pramipexole doses by mitigating the dose-limiting nausea and vomiting associated with pramipexole.
In June 2026, results from PRIME-PRAXOL — an independent, randomized, double-blind, placebo-controlled trial conducted by investigators at Lund University, Sweden — were published in Nature Medicine. Adults with major depressive disorder (搜索) (MDD), dysthymia, or bipolar depression (搜索) and clinically significant anhedonia received flexible-dose pramipexole or placebo added to ongoing treatment for nine weeks, followed by a six-month open-label extension.
The trial met its primary endpoint, with pramipexole reducing anhedonia significantly more than placebo on the Snaith–Hamilton Pleasure Scale (SHAPS) (mean difference −4.04; 95% CI −6.89 to −1.18; p=0.006; Hedges' g=0.62). Significant improvements were also observed on independent measures of anhedonia (DARS; p=0.008) and apathy (AES-S; p<0.001), and improvements were maintained through the six-month open-label period.
In an exploratory analysis included in the publication, an MDD diagnosis was significantly associated with greater SHAPS improvement at week 9 relative to dysthymia (p=0.038). In an additional analysis of the trial data not included in the publication, the MDD subgroup showed a larger effect on SHAPS at week 9 (Hedges' g=0.99) and a larger effect on the Hamilton Depression Rating Scale (HDRS-6) (Hedges' g=0.64).
Consistent with prior studies, adverse events were common in the pramipexole arm despite slow titration, including nausea in approximately 60% of participants — the dose-limiting tolerability constraint that the ALTO-207 (搜索) fixed-dose combination is designed to address.
"The Nature Medicine publication of PRIME-PRAXOL provides another independent, peer-reviewed dataset showing that dopaminergic treatment produces large effects in depression, and, just as importantly, a reminder of the tolerability challenge that ALTO-207 (搜索) is designed to address," said Etkin.
These findings are consistent with the broader body of evidence supporting ALTO-207 (搜索), including the PAX-D study conducted by the University of Oxford and published in The Lancet Psychiatry (Cohen's d=0.87 versus placebo at 12 weeks in TRD) and a meta-analysis of pramipexole in depression (Hedges' g=0.64, p<0.001).
The PACE Program: Three Late-Stage Trials
The broad development program for ALTO-207 (搜索), collectively the PACE program (Pramipexole-ondansetron Assessment of Clinical Efficacy in depression), remains on track across three large, well-controlled clinical trials.
The PACE-1 Trial (Phase 2b adjunctive TRD trial) is an ongoing, potentially registrational Phase 2b trial of ALTO-207 (搜索) as an adjunctive treatment in approximately 178 adults with TRD. Enrollment is on track with topline data expected in 2H 2027. MADRS is the primary endpoint in the trial, which is aligned with FDA standards in depression and supports the potential for the trial to contribute to a future registrational package alongside the planned Phase 3 trials.
The PACE-2 Trial (Phase 3 adjunctive TRD trial) remains on track to initiate by early 2027, following alignment with the FDA on the planned trial design. The Phase 3 trial is designed to run in parallel with the ongoing Phase 2b trial rather than await its topline data, an approach Alto believes can meaningfully accelerate the path to a potential NDA submission.
The PACE-3 Trial (Phase 3 monotherapy TRD trial) was announced in July 2026 as an additional planned Phase 3 trial evaluating ALTO-207 (搜索) as monotherapy in TRD. The Company believes a monotherapy dataset, alongside the planned adjunctive Phase 3 trial, could support a broader label and expand the addressable population for ALTO-207 if approved. Alto expects to initiate this trial in the second half of 2027 pending alignment with the FDA.
ALTO-207 (搜索) is being developed to address the significant unmet medical need in TRD, which is estimated to affect approximately 7 million adults in the United States.
Financial Position and Corporate Developments
For the quarter ended June 30, 2026, Alto Neuroscience reported a net loss of $27.6 million, compared to a net loss of $17.7 million for the same period in 2025. Research and development expenses were $22.1 million, up from $13.1 million in the prior-year period, while general and administrative expenses were $7.0 million, compared to $5.6 million in 2025.
As of June 30, 2026, the Company had cash, cash equivalents, and restricted cash of approximately $244.2 million, compared to approximately $177.0 million as of December 31, 2025. Giving effect to the net proceeds of the July 2026 offering, the Company's pro forma cash position following the offering was approximately $338 million.
In July 2026, Alto completed an underwritten registered direct offering of 3,776,436 shares of common stock at $26.48 per share, for gross proceeds of approximately $100.0 million and net proceeds of approximately $94.6 million. The Company intends to use the proceeds, together with existing cash, to accelerate and expand the clinical development of ALTO-207 (搜索), including the additional planned Phase 3 monotherapy trial in TRD, and for general working capital purposes.
Alto's patent estate covering ALTO-207 (搜索) includes multiple method-of-treatment patents protecting the use of ondansetron to mitigate pramipexole-related side effects to enable higher pramipexole dosing in the treatment of depression. Together with the Company's broader estate of issued and pending patents, Alto expects patent coverage of ALTO-207 through at least the mid-2040s.
Broader Pipeline and Upcoming Milestones
Enrollment remains ongoing in the Phase 2b trials of ALTO-300 in MDD and ALTO-100 in bipolar depression (搜索) (BPD), conducted under enhanced eligibility review and patient data quality procedures implemented earlier this year. Topline data remain expected in 1H 2027 for the ALTO-300 Phase 2b MDD trial and mid-2027 for the ALTO-100 Phase 2b BPD trial.
Expected upcoming milestones include the ALTO-207 (搜索) PACE-2 (Phase 3 adjunctive TRD) trial initiation in early 2027, ALTO-300 Phase 2b MDD topline data in 1H 2027, ALTO-100 Phase 2b BPD topline data in mid-2027, ALTO-207 PACE-1 (Phase 2b adjunctive TRD) topline data in 2H 2027, and ALTO-207 PACE-3 (Phase 3 monotherapy TRD) trial initiation in 2H 2027.
In June 2026, Alto was added to the Russell 2000 Index and the broad-market Russell 3000 Index, effective June 29, 2026. In May 2026, Alto appointed Andrew Miller, Ph.D., founder of Karuna Therapeutics, to its Board of Directors.