Today’s interim halt for efficacy to sacituzumab govitecan’s Ascent trial is certainly an unexpected bonus for a project mired in disappointments. But what makes this morning’s 100% surge in the share price of Immunomedics, its maker, hard to understand is that lack of clinical data was not one of its shortcomings. Sacituzumab already looked eminently approvable in third-line triple-negative breast cancer based on a phase I/II basket trial in which it yielded a 33% remission rate in what is a population with virtually no treatment options. Rather, its problem was repeated manufacturing failings that had led to a US complete response letter last year. Ascent was a confirmatory study, and was today said to have yielded “compelling efficacy” across several endpoints. Three years ago Seattle Genetics had attempted to license sacituzumab, an anti-Trop-2 antibody-drug conjugate, but amid an activist investor battle the deal was scrapped. Later, in the wake of the CRL Immunomedics lost its chief executive, and a replacement was appointed today. The company is now worth $4bn, and sacituzumab faces a June 2 Pdufa date; the question remains not whether its clinical package is strong enough but whether manufacturing is fit for purpose.
|Selected sacituzumab govitecan trials in triple-negative breast cancer|
|Phase 1/2 basket trial||515 subjects (108 with median 4th-line TNBC)||3CRs, 33PRs, mPFS 5.5mth, mOS 13.0mth|
|Ascent (phase 3 confirmatory)||529 subjects with ≥3rd-line TNBC||"Compelling efficacy" across several endpoints (PFS was primary, OS secondary)|
|Source: clinicaltrials.gov & NEJM.|