Zynlonta safety signal triggers death spike in confirmatory trial, sending ADC Therapeutics shares tumbling
In the LOTIS-5 Phase 3 trial for relapsed/refractory DLBCL, Zynlonta plus rituximab showed a higher death count (27) versus 9 in the control arm among 440 patients, with deaths characterized as treatment-emergent events and not definitively linked to the drug; safety concerns contributed to a more than 50% drop in ADC Therapeutics’ stock to about $1.44, even as the study met its primary endpoint of improved progression-free survival. There was no clear overall survival benefit, though higher response rates were reported. The company said it will discuss a path forward with the FDA and plans a supplemental filing for full approval in Q4.