Reactive Cutaneous Capillary Endothelial Proliferation in Esophageal Squamous Cell Carcinoma Patients Treated With...

Reactive cutaneous capillary endothelial proliferation (RCCEP) is the most common immune-related adverse event associated with camrelizumab and has been linked to favorable outcomes. We conducted a pooled analysis of two phase III randomized trials, ESCORT (NCT03099382) and ESCORT-1st (NCT03691090), to evaluate the clinical characteristics and prognostic relevance of RCCEP in patients with advanced esophageal squamous cell carcinoma (ESCC) receiving camrelizumab-based therapy. A total of 526 patients treated with camrelizumab, either alone or in combination with chemotherapy, were included. Objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were compared according to RCCEP status. Inverse probability of treatment weighting (IPTW) was applied to adjust for baseline imbalances, and a 2-month landmark analysis was performed to reduce lead-time bias. Overall, 420 patients (79.8%) developed RCCEP, mostly grade 1-2 (99.0%), with no RCCEP-related treatment discontinuations. The median onset was 1.18 months, and the duration was 3.12 months. RCCEP-positive patients showed a higher ORR (52.4% vs. 26.4%), longer PFS (5.55 vs. 1.94 months; HR = 0.45), and OS (13.40 vs. 6.11 months; HR = 0.47), consistent after landmark analysis. These findings suggested that RCCEP was frequent yet manageable and may serve as a potential on-treatment biomarker of camrelizumab benefit in ESCC.