enGene’s stock tumbled after updated Phase II LEGEND trial data for its nonviral gene therapy candidate detalimogene voraplasmid in high-risk BCG-unresponsive nonmuscle invasive bladder cancer. The updated readout showed lower complete response rates than prior results, with the any-time complete response at 54% and a six-month rate of 43%, down from earlier benchmarks reported for earlier cohorts. The repricing accelerated as investors absorbed concerns about durability and the gap versus expectations set by the November 2025 dataset. enGene said data remain preliminary and that longer-term durability analysis is planned for later in the year, alongside continued discussions with the FDA about potential regulatory pathways. The episode illustrates how quickly investors can recalibrate around clinical readouts in gene delivery, even when programs are still maturing across cohorts.