Mersana Therapeutics’ UPLIFT trial ‘failed to replicate’ previous efficacy data

Mersana Therapeutics announced that the UPLIFT clinical trial of upifitamab rilsodotin (UpRi) did not meet its primary endpoint. UpRi is an ADC targeting the sodium-dependent phosphate transport protein NaPi2b and was developed utilizing the company’s Dolaflexin platform. UPLIFT enrolled a total of 268 patients, 141 of whom were determined to be NaPi2b positive. Safety and tolerability data in UPLIFT were generally consistent with prior disclosures. Following the completion of its analyses, the company plans to share detailed efficacy and safety data with the medical and scientific community in an appropriate forum. “We are deeply disappointed that UPLIFT’s efficacy failed to replicate previous data from approximately 100 patients in the dose expansion portion of our Phase 1b clinical trial,” said Dr. Arvin Yang, Senior Vice President and Chief Medical Officer of Mersana Therapeutics. “While the duration of response was longer than that from the dose expansion portion of UpRi’s Phase 1b clinical trial, the lower bound of the confidence interval for the primary endpoint did not meet our goal of excluding a 12% ORR seen with standard-of-care single-agent chemotherapy. We are in the process of conducting an in-depth analysis of various factors to better understand the results as well as the characteristics of patients who responded to UpRi therapy, particularly those whose responses were deep and durable. We extend our deepest gratitude to all of the patients, family members, caregivers and investigators who contributed to UPLIFT.”