Reactive Cutaneous Capillary Endothelial Proliferation in Esophageal Squamous Cell Carcinoma Patients Treated With Camrelizumab‐Based Therapy: A Pooled Analysis of Two Phase 3 Trials
Jia Liu, Ye He, Mingming He, Fan Chen, Zhiguo Hou, Zhaoqing Zheng, Chaoyu Lin, Aichun Chen, Ruihua Xu, Huiyan Luo,ABSTRACT
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.