Mersana Therapeutics announces partial clinical hold for XMT-1522 trial
Mersana Therapeutics announced that the U.S. Food and Drug Administration has placed the Phase 1 study of XMT-1522 on partial clinical hold. While the partial clinical hold remains in effect, no new patients will be enrolled in the study, though current study participants in its ongoing dose levels will continue to receive drug and otherwise participate in the trial consistent with its protocol. The partial clinical hold was initiated following Mersana's recent report to the FDA of a Grade 5 Serious Adverse Event, patient death, in dose level 7 of the XMT-1522 Phase I trial, which was classified by the investigator as possibly drug-related. Mersana will be working closely with the FDA and the site investigators to review this event and to seek to resolve this clinical hold. The partial clinical hold does not affect the ongoing clinical development of Mersana's product candidate XMT-1536, currently in Phase 1 clinical trials for NaPi2b-expressing cancers.