Fig. 1: Study design.

a, Study schema. CONSORT diagram disposition of all patients who received monotherapy comprising the safety analysis population (b) and of those in the dose-optimization cohorts who were included in the primary efficacy and RP2D analysis (c). This phase 1, open-label, dose-escalation and dose-expansion study of ABBV-706 in patients with advanced solid tumors with potential SEZ6 expression comprised four parts: part 1 was dose escalation of ABBV-706 monotherapy and included all advanced solid tumors; part 2 (a, b and c) was dose optimization/expansion of ABBV-706 monotherapy in R/R SCLC; and part 4 was dose expansion of ABBV-706 monotherapy in R/R CNS tumors (4a) and high-grade NENs (4b). Data from part 3 (ABBV-706 combination therapy) are not reported. ^aIV Q3W in 21-day cycles until disease progression or unacceptable toxicity. ^bPart 2b was not pursued. ^cOne patient in this cohort was ineligible. ^dThe totality of efficacy, safety and PK data from part 1 and part 2 confirmed 1.8 mg kg⁻¹ as the optimal dose for patients with R/R SCLC. ^en = 30 patients were screened and enrolled in the ABBV-706 plus budigalimab combination cohorts, which are not reported here. ^f Part 3b was halted after enrollment of 18 patients; data from this cohort are not reported here. BOIN, Bayesian optimal interval; ES, extensive stage; IV, intravenous.