Mersana Therapeutics announces clinical hold on XMT-2056 Phase 1 trial

Mersana Therapeutics announced that the Phase 1 trial of XMT-2056 has been placed on clinical hold by the U.S. Food and Drug Administration. This action follows the company’s communication to FDA that Mersana was voluntarily suspending the trial due to a recent Grade 5 serious adverse event that was deemed to be related to XMT-2056. The SAE and its cause remain under investigation. XMT-2056 is Mersana’s first Immunosynthen STING-agonist ADC product candidate to enter the clinic, and the SAE occurred in the second patient who had been enrolled at the initial dose level in the dose escalation portion of the Phase 1 trial in previously treated patients with HER2+ recurrent or metastatic solid tumors. During the clinical hold, no patients will be enrolled or dosed in the trial.