AbbVie initiated a first-in-human study of ABBV-706, an antibody-drug conjugate targeting SEZ6 in patients with advanced solid tumors. The program represents a new mechanism exploration for ADCs against a neuro-associated antigen target. The article text provided indicates the work is described in a Journal of Clinical Oncology supplement context, with study author and citation metadata included. Key early outcomes—such as dose-escalation tolerability, preliminary response rates, and pharmacokinetics—were not included in the excerpt. For the field, ADC development continues to broaden beyond standard solid-tumor antigen targets. The immediate industry watchpoint will be how ABBV-706 performs on safety and target engagement in early cohorts and whether any signals emerge for specific tumor histologies.