The interim Phase 1b dataset included eight efficacy-evaluable patients at cutoff, with post-cutoff confirmation lifting the reported rate to 89 percent in nine evaluable patients
REDWOOD CITY, California, October 28, 2026. Coherus Oncology reported interim Phase 1b results for tagmokitug with toripalimab and chemotherapy in previously untreated advanced or metastatic esophageal squamous cell carcinoma. At the October 14 cutoff, eight patients were efficacy evaluable and six had confirmed responses, producing a 75 percent confirmed objective response rate.
The company said two further partial responses were confirmed after the cutoff, increasing the rate to eight of nine evaluable patients, or 89 percent. Among patients classified as PD-L1 positive, the confirmed response rate was reported as 100 percent. Enrollment is continuing, and the primary endpoint of the cohort is safety rather than a definitive comparison of efficacy.
Tagmokitug is an investigational cytolytic antibody directed at CCR8, a marker associated with suppressive regulatory T cells in tumors. The development hypothesis is that depleting these cells may reduce local immune suppression and allow checkpoint blockade to work more effectively. Toripalimab targets PD-1, while chemotherapy contributes direct tumor-cell killing and immune effects.
The four-drug first-line regimen makes attribution difficult. A response cannot be assigned to tagmokitug without a randomized control because toripalimab and chemotherapy are active components. The result can establish a clinical signal and support expansion, but it cannot prove that adding the CCR8 antibody improves survival or response beyond an appropriate standard regimen.
The difference between six of eight and eight of nine illustrates why data cutoffs and denominators must accompany percentages. Post-cutoff updates can be informative, but mixing observation dates can make comparisons unstable. Future releases should preserve the prespecified cutoff, distinguish confirmed and unconfirmed responses and provide confidence intervals, follow-up and duration of response.
One confirmed complete response was reported at cutoff. The clinical importance will depend on durability, progression-free survival and overall survival. Early response rates in a small cohort may be influenced by patient selection, imaging timing and baseline disease burden. Randomized evidence is needed before the regimen can be described as better than current care.
In second-line esophageal squamous cell carcinoma, six patients were efficacy evaluable at the selected 700 milligram dose. Coherus reported one confirmed response, a 33.3 percent clinical-benefit rate and median progression-free survival of 5.5 months. The numbers are too small for reliable cross-study comparison, although they can guide continued enrollment and dose evaluation.
The company also reported activity in HPV-positive head-and-neck cancer, upper gastrointestinal cancers and heavily pretreated microsatellite-stable colorectal cancer. These are biologically and clinically distinct populations. A platform claim should not combine them into one efficacy estimate. Each indication needs its own endpoint, comparator, biomarker strategy and evidence threshold.
Across more than 120 patients treated with tagmokitug plus toripalimab, the company reported immune-related adverse events in 40 percent at any grade and in 20 percent at Grade 3 to 5. Common treatment-related events included infusion reactions, fatigue and rash. No Grade 5 treatment-related adverse events were reported.
Removing regulatory T cells could improve antitumor immunity but may also alter immune tolerance. Longer follow-up should examine autoimmune toxicity, infections, delayed immune events and whether adverse effects differ by dose or combination. The first-line cohort also requires separation of chemotherapy toxicity from immune-mediated events.
The results give clinical support to a CCR8 strategy and justify a larger esophageal-cancer program. They also demonstrate the risk of overinterpreting a high percentage generated from fewer than ten evaluable patients. The most valuable next step is not another headline response rate but a controlled trial that isolates tagmokitug’s contribution.
Coherus plans to expand first-line and second-line enrollment and evaluate durability, progression-free survival and biomarkers. Tagmokitug remains unapproved. The next development decision should integrate mature follow-up, the Tumor Immune Regulatory Index research and a comparator reflecting regional standards of care.
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