Coherus Oncology, Inc. filed a Form 8-K on October 28, 2026, disclosing interim clinical data from the TREGCHECK development program evaluating tagmokitug, its investigational cytolytic CCR8 antibody, in combination with toripalimab, with or without chemotherapy, across multiple solid tumor indications.

Key Highlights

  • First-line ESCC confirmed ORR: In 8 efficacy-evaluable patients in TREGCHECK 102 Cohort C, tagmokitug plus toripalimab and chemotherapy achieved a confirmed overall response rate of 75% (6/8) irrespective of PD-L1 status, as of the October 14, 2026 data cutoff.
  • Post-cutoff update: After the data cutoff, two additional partial responses were confirmed, increasing the cORR to 89% (8/9) of the evaluable patient dataset irrespective of PD-L1 status.
  • PD-L1 positive patients: Confirmed overall response rate of 100% in PD-L1 positive first-line ESCC patients was reported as of October 14, 2026.
  • Second-line ESCC mPFS: In the 700 mg tagmokitug arm of TREGCHECK 102 Cohort B, median progression-free survival was 5.5 months, compared to a US standard-of-care benchmark of approximately 3.4 months for chemotherapy, according to the filing.
  • Safety profile: Among more than 120 patients treated with tagmokitug in combination with toripalimab, no Grade 5 treatment-related adverse events were reported, and the overall rate of immune-related adverse events was 40% for all grades, with 20% experiencing Grade 3-5 events.
  • No regulatory approval: The filing states that tagmokitug "has not been approved by the U.S. Food and Drug Administration or any other regulatory authority" and that "its safety and efficacy have not been established."
  • Next steps: The company disclosed plans to expand enrollment in first-line and second-line ESCC cohorts and to advance a planned study evaluating tagmokitug with a T-cell engager in mCRPC.

Interim TREGCHECK Data: Tagmokitug Activity Across Solid Tumor Cohorts

According to the filing, Coherus Oncology reported interim results from the TREGCHECK development program, covering multiple cohorts in esophageal squamous cell carcinoma, head and neck squamous cell carcinoma, upper gastrointestinal cancers, and microsatellite-stable colorectal cancer. The data cutoff for the primary results was October 14, 2026. The company disclosed that tagmokitug-based treatment "demonstrated encouraging anti-tumor activity across multiple solid tumors, including responses and durable disease stabilization in pretreated and immunotherapy-resistant patients."

In the first-line ESCC cohort (TREGCHECK 102 Cohort C), 10 patients were safety evaluable and 8 were efficacy evaluable at the data cutoff. The filing reports a cORR of 75% (6/8) in all comers and 100% in PD-L1 positive patients, with one confirmed complete response. For context, the filing notes that the US standard-of-care benchmark for PD-1 inhibitor plus chemotherapy in PD-L1 positive ESCC carries a cORR of 44% to 59%. In the second-line ESCC cohort (Cohort B), 17 patients were safety evaluable and 8 were efficacy evaluable across both dose arms. The 700 mg arm showed a clinical benefit rate of 33.3% (2/6) and a cORR of 16.7% (1/6), with a median progression-free survival of 5.5 months.

In the head and neck squamous cell carcinoma cohort, the filing reports a cORR of 13.0% (3/23) and a clinical benefit rate of 26.1% (6/23) in HPV-positive efficacy-evaluable patients across both doses. In the upper GI cohort, 4 confirmed partial responses were observed among 17 evaluable patients at the 700 mg dose, yielding a cORR of 23.5%. The 4L-plus non-liver-metastasis microsatellite-stable colorectal cancer cohort showed a 5.9% cORR and 11.8% clinical benefit rate in 17 efficacy-evaluable patients. The filing also noted that in 33 monotherapy patients, no dose-limiting toxicities were observed through the 1200 mg every-three-week dose level. The filing contains forward-looking statements, which the company identifies as subject to the cautionary language of the Private Securities Litigation Reform Act of 1995.

What Was Disclosed

Coherus Oncology filed an 8-K on October 28, 2026, under Items 7.01 and 8.01, furnishing and reporting interim clinical data from the TREGCHECK program for tagmokitug, an investigational CCR8 antibody, across several solid tumor cohorts, with data as of October 14, 2026.