1. In this phase II randomized clinical trial, treatment of patients with locally advanced esophageal squamous cell carcinoma (ESCC) with socazolimab prior to minimally invasive esophagectomy achieved lower major pathological response (MPR) rates than treatment with placebo, though this difference did not reach statistical significance.
2. The proportion of primary tumours at the ypT0 stage in the socazolimab and cisplatin group was significantly higher than in the placebo and cisplatin group.
Evidence Rating Level: 1 (Excellent)
The prognosis for esophageal cancer is poor, with a 5-year survival rate currently less than 20%. Surgery-based combination therapy is the primary treatment for non-metastatic esophageal squamous cell carcinoma (ESCC), and neoadjuvant concurrent chemotherapy is an essential part of preoperative treatment that can improve resection and survival rates. Programmed cell death ligand 1 (PD-L1) inhibitors are a relatively overlooked checkpoint inhibitor for ESCC; emerging evidence has shown promising results of socazolimab, a novel humanized IgG1 monoclonal antibody against PD-L1, in patients with small-cell lung cancer and cervical cancer. Thus, this multicenter, randomized, double-blind phase II study was designed to assess the feasibility, safety, and efficacy of neoadjuvant socazolimab and chemotherapy followed by minimally invasive esophagectomy in patients with resectable locally advanced ESCC. This study was conducted at six hospitals in China, and patients that were recruited In phase II were randomly divided in a 1:1 ratio between the experimental (socazolimab + nab-paclitaxel + cisplatin (TP)) and control (placebo + TP). All patients underwent video-assisted thoracoscopic esophagectomy between 4 and 6 weeks after neoadjuvant treatment. The main endpoint was the major pathological response (MPR) rate. Overall, 64 patients were recruited in phase II and were equally divided into the two arms, with no significant clinical characteristics found between the two groups. Of patients who underwent surgery, 29 (100.0%) in the Socazolimab + TP group and (96.6%) in the Placebo + TP group reached R0. Furthermore, with respect to the primary endpoint, 20 (69.0%) patients in the Socazolimab + TP group and 18 (62.1%) patients in the Placebo + TP group reached MPR (P=.581). Notably, the proportion of primary tumours at the ypT0 stage in the Socazolimab + TP group was considerably higher than in the Placebo + TP group (37.9% vs. 3.5%; P=.001). Overall, in this randomized controlled trial, treatment with socazolimab, nab-paclitaxel, and cisplatin demonstrated a better antitumour effect than the placebo with cisplatin, though this difference was not statistically significant. However, the proportion of patients achieving complete regression of the primary tumour was significantly higher in the socazolimab and cisplatin group versus the placebo and cisplatin group, indicating the PD-L1 inhibitor approach enhanced regression of the primary tumour. A major limitation of this study is the short follow-up time, as we are not yet able to appreciate any differences between median survival between the two groups. This study is an important addition to the growing body of evidence surrounding PD-L1 inhibitors and their use in ESCC.
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