Tortugas Neuroscience Reports Positive Phase 2b Results for Schizophrenia Drug

Tortugas Neuroscience has reported positive Phase 2b trial results for obuprazine, an investigational schizophrenia treatment licensed from China’s Hansoh Pharma. The study found statistically significant and clinically meaningful improvements in schizophrenia symptoms across all three tested obuprazine dose groups compared with placebo. The findings also showed an early clinical response and a generally favorable tolerability profile.

Also known as TRTL-107, obuprazine was evaluated in a randomized, double-blind, placebo- and active-reference-controlled study involving 363 Chinese adults with acute schizophrenia who had required hospitalization within two months before screening. Participants were assigned to one of five groups: three obuprazine dose ranges, aripiprazole, an approved antipsychotic, or placebo.

The primary endpoint was the change from baseline in the Positive and Negative Syndrome Scale (PANSS) total score at Day 42. All three obuprazine dose groups achieved statistically significant and clinically meaningful improvements compared with placebo.

Lower Dose Shows Largest Treatment Effect

The 1.5–3.0 mg group recorded the largest treatment effect, with a mean PANSS score reduction of 28.6 points from baseline, compared with 11.9 points in the placebo group. This represented a placebo-adjusted difference of 16.7 points, with a p-value below 0.0001.

The 4.5–6.0 mg and 6.0–9.0 mg groups recorded placebo-adjusted improvements of 13.2 and 14.7 points, respectively. Both results were statistically significant, with p-values below 0.0001.

At Day 42, improvements were also recorded across the PANSS positive and negative symptom subscales and the Marder cognitive factor scores. In the 1.5–3.0 mg group, placebo-adjusted improvements reached 5.3 points for positive symptoms and 4.4 points for negative symptoms. Both results had p-values below 0.0001.

Early Response and Safety Findings

An analysis of PANSS responder rates, defined as a reduction of at least 50% from baseline, found higher response rates in the 1.5–3.0 mg and 4.5–6.0 mg groups than in both the placebo and aripiprazole groups as early as Day 14.

Tortugas also reported numerically greater efficacy for obuprazine than aripiprazole across multiple endpoints, including the primary endpoint.

The drug was generally well tolerated during the study. Treatment discontinuation rates were approximately 2.1% among patients receiving obuprazine, compared with 2.5% in the placebo group.

Company Outlines Drug’s Pharmacological Profile

Al Robichaud, Tortugas Neuroscience’s president and head of research and development, described the findings as consistent with obuprazine’s pharmacological profile.

“We are particularly encouraged by the results observed across dose levels, which may provide physicians flexibility to optimize treatment based on individual patient needs,” Robichaud said.

Obuprazine is a D2/D3 partial agonist and a 5-HT2A antagonist. According to Robichaud, its pharmacological activity also involves functional modulation of dopamine D2, D3 and 5-HT1A receptors. He said this combination may support improvements across multiple symptom domains while potentially addressing tolerability limitations.

U.S. Regulatory Plans and Wider Pipeline

Tortugas plans to submit a U.S. Investigational New Drug (IND) application for TRTL-107. Detailed results from the Phase 2b study are expected to be submitted for publication in a peer-reviewed journal.

The company launched in April with $106 million in funding and a pipeline of four licensed clinical-stage assets. Alongside obuprazine, its programs include a Hansoh compound targeting tinnitus through positive allosteric modulation of GABA receptors, an Eisai-licensed GAT-1 inhibitor for focal epilepsy, and an Eisai-licensed PDE9 inhibitor for reversible encephalopathies. All three additional programs are in Phase 2.

Tortugas was established by former Sage Therapeutics colleagues Jeff Jonas, its chief executive officer, and Robichaud. At launch, the company said its strategy was to develop medicines with clear regulatory paths to approval, focusing on small molecules with derisked mechanisms of action that could be developed as once-daily oral formulations for large, well-defined indications.

Tortugas Neuroscience announced positive Phase 2b clinical trial results on October 12, 2026, for obuprazine (TRTL-107), an investigational treatment being developed for schizophrenia. The study, conducted by its partner Hansoh Pharma, met its primary endpoint and demonstrated statistically significant improvements in schizophrenia symptoms across all three tested dose groups. The results were presented at the 2026 European College of Neuropsychopharmacology (ECNP) Congress.

The announcement represents an important milestone for Tortugas Neuroscience as it works to advance treatments for central nervous system disorders. Schizophrenia remains a significant therapeutic challenge, with patients potentially experiencing persistent symptoms and limitations in daily functioning despite available treatments.

What Makes the Results Important for Tortugas Neuroscience?

The positive trial results could help Tortugas Neuroscience advance its clinical development strategy. The company focuses on treatments for neurological and psychiatric conditions, including schizophrenia, tinnitus, focal epilepsy, and certain cognitive disorders.

Obuprazine is its leading clinical candidate. Tortugas Neuroscience holds global commercial development rights outside Greater China, while Hansoh Pharma conducted the reported Phase 2b study.

The company has stated that it plans to submit a U.S. Investigational New Drug (IND) application for TRTL-107. Such an application would support the regulatory process for evaluating the drug in U.S. clinical studies; it would not itself represent marketing approval.

Further development will require additional evidence regarding safety, efficacy, dosing, and the durability of treatment effects.

The Unmet Need for New Schizophrenia Treatments

Schizophrenia is a complex psychiatric condition that can affect perception, thinking, emotional expression, and everyday functioning. Existing antipsychotic treatments can help many patients, but treatment response and tolerability vary, and some individuals continue to experience significant symptoms.

Tortugas Neuroscience is pursuing obuprazine as a potential treatment option that could provide broad symptom improvement while maintaining an acceptable tolerability profile.

The Phase 2b results offer an encouraging early clinical signal. However, independent assessment, peer-reviewed publication, and further trials will be important for determining how consistently these benefits can be reproduced and which patients might benefit most.

Next Steps in Obuprazine Development

Following the positive Phase 2b findings, Tortugas Neuroscience plans to advance the program toward the next stage of development. The planned U.S. IND submission represents an important regulatory milestone, while the publication of detailed trial results could provide additional information for clinicians and researchers.

Future studies will need to clarify the treatment’s safety and efficacy in larger and more diverse populations, evaluate longer-term outcomes, and determine how obuprazine compares with established treatment options.

For the biotechnology sector, the program also illustrates the importance of partnerships in drug development, particularly when clinical assets are advanced across different geographic markets.

Conclusion

The positive Phase 2b results for obuprazine represent a significant development for Tortugas Neuroscience and its efforts to advance new treatments for schizophrenia. The trial met its primary endpoint and reported improvements across several symptom measures, alongside low treatment discontinuation rates due to adverse events.

While the findings offer encouraging evidence for continued research, obuprazine remains investigational. Additional clinical studies and regulatory review will be necessary before its potential benefits and risks can be fully established.

For patients, clinicians, and the biotechnology industry, the next phase of development will determine whether this candidate can become a meaningful addition to schizophrenia treatment options.

Key Findings From the Phase 2b Schizophrenia Trial

The randomized, double-blind, placebo- and active-reference-controlled study enrolled 363 Chinese adults with acute schizophrenia across 24 clinical centers. Participants received one of three obuprazine dose ranges, aripiprazole as an active reference, or placebo.

The primary endpoint measured changes in the Positive and Negative Syndrome Scale (PANSS) total score after 42 days of treatment. All three obuprazine dose groups achieved statistically significant improvements compared with placebo.

Key findings included:

• Low-dose group: The 1.5–3.0 mg group achieved a placebo-adjusted improvement of 16.7 points in PANSS total score.

• Middle-dose group: The 4.5–6.0 mg group demonstrated a placebo-adjusted improvement of 13.2 points.

• High-dose group: The 6.0–9.0 mg group achieved a placebo-adjusted improvement of 14.7 points.

• Broad symptom improvements: The trial reported improvements in positive symptoms, negative symptoms, and the Marder cognitive factor.

• Tolerability: Treatment discontinuation due to adverse events was approximately 2.1% in obuprazine-treated patients, compared with 2.5% for placebo.

These findings are encouraging, but further clinical development is needed to establish the treatment’s longer-term benefits, safety profile, and potential role in clinical practice.

How Obuprazine Could Address Schizophrenia Symptoms

Obuprazine, also known as TRTL-107, is an investigational drug designed to act on several neurotransmitter receptors involved in brain signaling. Its pharmacological profile includes partial agonism at dopamine D2 and D3 receptors, antagonism at serotonin 5-HT2A receptors, and partial agonism at serotonin 5-HT1A receptors.

Tortugas Neuroscience believes this mechanism may support improvements across multiple symptom domains. The Phase 2b results showed benefits beyond the primary endpoint, including measures of positive and negative symptoms and cognition-related functioning.

Positive symptoms can include hallucinations and delusions, while negative symptoms may involve reduced motivation, diminished emotional expression, and social withdrawal. Cognitive difficulties can also affect daily functioning and independence.

Although the reported results suggest potential across these areas, the findings do not establish that obuprazine will be more effective or better tolerated than currently available treatments in broader patient populations.