Atezolizumab + Tiragolumab (PD-L1/TIGIT) Shows Index Node pCR Can Miss Melanoma

Atezolizumab is an anti–PD-L1 antibody and tiragolumab is an anti-TIGIT antibody evaluated in a preplanned NeoACTIVATE Arm C substudy (NCT03554083) asking whether clipped index lymph node (ILN) pathology can substitute for full nodal-basin pathology after neoadjuvant doublet immunotherapy in resectable clinical stage III macroscopic nodal melanoma. Among 30 patients who underwent therapeutic lymph node dissection (TLND), ILN and basin pathology were discordant in 2 patients (6.7%); both had ILN pCR but residual non-ILN disease, yielding a 13.3% false-negative rate for ILN pCR as a basin-clearance surrogate. No new safety signal was reported, but the relevant benchmark is surgical adequacy: PRADO-style response-directed surgery after neoadjuvant ipilimumab/nivolumab explored TLND omission only after index-node MPR, while TLND remains the conventional fallback for clinically evident nodal disease.