Sensei Biotherapeutics Reports Favorable Preliminary Dose Expansion Data for Solnerstotug in PD-(L)1 Resistant Tumors

Core Insights - Sensei Biotherapeutics has reported initial clinical activity of solnerstotug in a PD-(L)1 resistant population, showing an overall response rate (ORR) of 14%, which is nearly three times higher than historical response rates for PD-(L)1 rechallenge [1][3][4] - The study included patients with various "hot" tumors and demonstrated durable responses, including a complete response in a Merkel Cell Carcinoma (MCC) patient and partial responses in other patients [1][6][13] - The company plans to initiate a Phase 2 study in Q1 2026, pending sufficient capital, with ongoing analyses to optimize patient selection and trial design [10] Company Overview - Sensei Biotherapeutics is a clinical-stage biotechnology company focused on developing next-generation immunotherapies for cancer, utilizing its TMAb™ platform to create conditionally active therapeutics [14] - The lead product candidate, solnerstotug, targets VISTA to restore T cell activity in tumors resistant to checkpoint inhibitors [14] Clinical Trial Details - The Phase 1 dose expansion trial is evaluating solnerstotug as a monotherapy and in combination with Libtayo (cemiplimab) across various tumor types, including both "hot" and "cold" tumors [4][6] - As of March 17, 2025, the trial has enrolled 60 patients, with 21 evaluable PD-(L)1 resistant "hot" tumor patients showing a 14% ORR and a 62% disease control rate (DCR) [5][6] Safety and Tolerability - Solnerstotug has been well tolerated, with no dose-limiting toxicities reported; the majority of adverse events (AEs) were Grade 1 or 2 in severity [7] - There were four cases (7%) of Grade 1 cytokine release syndrome, all mild and manageable [7] Treatment Landscape - Patients with PD-(L)1 resistant tumors face a poor prognosis, with a ≤5% likelihood of response to PD-(L)1 rechallenge, highlighting a significant unmet medical need [3][8] - Current treatment options for these patients are limited, often involving chemotherapy or experimental therapies [8] Future Directions - The company is preparing for the Phase 2 study, with plans to incorporate biomarker-based patient selection strategies based on ongoing trial results [10]