Sensei Biotherapeutics Reports Favorable Initial Clinical Activity Data For Solnerstotug In Resistant Tumors

Sensei Biotherapeutics Inc. (NASDAQ:SNSE) late Thursday released initial results from the dose expansion portion of its Phase 1/2 trial evaluating solnerstotug (formerly SNS-101) for cancer.

The Phase 1 dose expansion trial is evaluating solnerstotug as monotherapy and in combination with Regeneron Pharmaceuticals Inc.‘s (NASDAQ:REGN) Libtayo (cemiplimab) in both a basket of “hot” tumors that typically respond to immunotherapy but have progressed on prior PD-(L)1 therapy and a single “cold” tumor histology (microsatellite stable (MSS) Colorectal Cancer (CRC) that is typically unresponsive to immunotherapy.

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As of March 17, the study has enrolled 60 patients. Key findings include:

• Among 21 evaluable PD-(L)1 resistant “hot” tumor patients, the combination of solnerstotug + cemiplimab demonstrated a 14% ORR (overall response rate), which is almost 3x higher than historical PD-(L)1 rechallenge response rates (≤5%), and a 62% DCR (disease control rate), suggesting meaningful disease control in resistant tumors.
• One durable complete response in a patient with Merkel Cell Carcinoma (MCC).
• Two partial responses (PRs): one in a second MCC patient and one in a microsatellite instability-high (MSI-H) CRC patient.
• All patients with tumor shrinkage remain on treatment, suggesting potential for prolonged clinical benefit.
• An additional 11 patients have not yet reached the first baseline scan, and an additional eight patients discontinued the study before any post-baseline scan.
• All patients in this cohort had progressed on prior PD-(L)1.

Six PD-(L)1 resistant patients with stable disease remain on treatment past 12+ weeks, with tumor reductions ranging from 0% to 17%, suggesting durable disease control in a subset of patients.

All PD-(L)1 resistant patients on the study with tumor shrinkage remain on treatment, suggesting the potential for prolonged benefit.

None of the MSS CRC patients experienced a CR or PR, consistent with prior checkpoint therapy in this “cold” tumor type.

Solnerstotug continues to be well tolerated, with no dose-limiting toxicities and the majority of AEs Grade 1 or 2 in severity.

Out of 60 patients, there have been four (7%) cases of Grade 1 cytokine release syndrome (CRS), all mild and manageable. Two patients in the combination cohort experienced immune-mediated events.

Price Action: SNSE stock is up 32.31% at $0.57 at the last check Friday.

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