FDA lifts partial clinical hold for XMT-1522 trial

The US Food and Drug Administration has lifted the partial clinical hold on the Phase I study of XMT-1522 for NaPi2b-expressing cancers.

Shares of the drug’s developer, Mersana Therapeutics (Nasdaq: MRSN), plunged 40% back in July, when the FDA placed the restriction on the trial following a patient death possibly linked to the drug, which is out-licensed to Japan’s Takeda (TYO: 4502) outside the USA and Canada. Surprisingly, the shares in early trading yesterday fell 22.5% to $11.14, but rose 4.9% to $11.69 in after-hours trading.

Mersana and the FDA reached alignment on changes to the protocol, including increased monitoring as well as the exclusion of patients with advanced hepatic impairment.  Although XMT-1536, Mersana’s dolaflexin ADC targeting NaPi2b, was not subject to a clinical hold, Mersana has decided to implement similar modifications to the XMT-1536 protocol.