Mersana Therapeutics, Inc. 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 was a single-arm clinical trial that enrolled platinum-resistant ovarian cancer patients with one to four prior treatment regimens.

The primary endpoint for UPLIFT was the investigator-assessed objective response rate (ORR) in the NaPi2b-positive population. NaPi2b-positive status was defined by a tumor proportion score (TPS) of >=75%. Secondary endpoints for the trial included the investigator-assessed ORR among all patients in the trial, duration of response (DOR), and safety and tolerability.

The trial also included an assessment of ORR and DOR by independent radiology review (IRR). UPLIFT enrolled a total of 268 patients, 141 of whom were determined to be NaPi2b positive. The median prior lines of systemic therapy among all patients was three, with 31% of the population having received four prior lines of treatment.

Additionally, 84% of patients received prior bevacizumab and 69% received prior PARP inhibitor treatment.