Mersana Therapeutics, Inc. announced that patient dosing is underway in the expansion portion of its UPGRADE-A clinical trial of UpRi in combination with carboplatin in platinum-sensitive ovarian cancer. UpRi is Mersana's first-in-class NaPi2b-targeting ADC with a novel scaffold-linker-payload designed to enable a high drug-to-antibody ratio and controlled bystander effect. UPGRADE-A is a Phase 1 open-label trial evaluating the combination of UpRi and carboplatin in patients with platinum-sensitive high-grade serous ovarian cancer following one to three prior lines of treatment.

Patients in the trial receive combination treatment every four weeks for six cycles followed by UpRi as a single-agent maintenance therapy. While patients in the trial are not preselected for NaPi2b-positive status, archival or fresh tissue is required for retrospective assessment of expression. The escalation portion of the trial investigated carboplatin combined with UpRi doses up to 36 mg/m2.

There were no dose-limiting toxicities at this dose level. Consistent with Mersana's UP-NEXT Phase 3 clinical trial, a 30mg/m2 dose of UpRi has been chosen for the dose expansion portion of UPGRADE-A. Mersana expects to report interim data from UPGRADE-A in the second half of 2023.