AbbVie’s ABBV-706, an antibody-drug conjugate directed at SEZ6 with a topoisomerase inhibitor payload, achieved a 56 percent objective response rate and median overall survival of 12.4 months at its selected Phase 3 dose of 1.8 mg/kg in heavily pretreated relapsed or refractory small cell lung cancer, in updated Phase 1 findings AbbVie summarised for ESMO. The dose cohort held 41 patients treated in second line or later. In the second-line-only subset of 17 patients, the response rate was 82 percent and median survival was 14.4 months. AbbVie said safety was comparable to previously reported data and that biomarker findings support SEZ6 as a therapeutic target.
AbbVie is already testing the drug in a randomised Phase 3 trial against standard of care in relapsed or refractory small cell lung cancer, NCT07365241, which is the correct next step: Phase 1 response rates in selected, heavily pretreated cohorts are not comparable across trials, and the second-line subset here is 17 patients.
The context that makes this more than a pipeline note is timing. Amgen’s Imdelltra plus Imfinzi produced a 58 percent reduction in the risk of death as first-line maintenance in extensive-stage small cell lung cancer in Phase 3 data presented at this same congress and covered on October 24. If both programs advance, small cell lung cancer, a disease with few durable options, gains two mechanistically distinct entrants, a bispecific T cell engager in earlier disease and an ADC in relapsed disease, competing on different lines of therapy rather than head to head.
No new safety figures, response duration or randomised data were in the sponsor’s summary, so this story carries the Phase 1 numbers at the weight they deserve: a reason the Phase 3 exists, not a forecast of its result.