Sometimes good news just isn't good enough. ADC Therapeutics SA (ADCT) learned that lesson the hard way on Wednesday when its stock cratered more than 23% despite what looked like genuinely impressive cancer trial data.
The company released updated results from its LOTIS-7 Phase 1b trial testing Zynlonta combined with glofitamab (Columvi) in patients with relapsed or refractory diffuse large B-cell lymphoma. The numbers themselves were strong, but investors apparently focused on other aspects of the announcement that gave them pause.
The Trial Data
As of the November 17, 2025 data cutoff, 49 patients were evaluable with at least six months of follow-up. The headline numbers were striking: the best overall response rate hit 89.8%, with 44 out of 49 patients responding to treatment.
Even more impressive, the complete response rate reached 77.6%, meaning 38 patients saw their cancer essentially disappear. Of those 38 complete responders, 33 remained in complete response at the data cutoff. The five who didn't included two with progressive disease, two who experienced fatal adverse events during their response, and one censored patient.
The combination showed strong performance across different patient populations. Among the 24 relapsed patients, the response rate was a perfect 100% with a 91.7% complete response rate. The primary refractory population, typically harder to treat, still posted an 80% overall response rate and 64% complete response rate.
There were other encouraging details too. Fourteen patients who initially had stable disease or partial responses eventually converted to complete responses over time. And among eight patients previously treated with CAR-T therapy, six achieved complete responses.
What Spooked Investors
Despite the promising efficacy numbers, the stock plunged as concerns about the safety profile and trial timeline emerged. The company noted the combination was "generally well tolerated with a manageable safety profile," but those two Grade 5 adverse events (medical speak for fatal) likely caught attention.
Enrollment in LOTIS-7 continues, with full enrollment of roughly 100 patients at the selected 150 µg/kg dose expected during the first half of 2026. The company plans to present complete data at a medical meeting and submit for publication by the end of 2026.
ADC Therapeutics shares closed down 23.15% at $3.53 on Wednesday, a stark reminder that in biotech investing, even good data doesn't guarantee a positive market reaction.
