448. PREOPERATIVE PEMBROLIZUMAB COMBINED WITH CHEMOTHERAPY FOR THORACIC ESCC WITH CERVICAL LYMPH NODE METASTASIS (PICC-1): A PROSPECTIVE, PHASE 2 STUDY

Abstract Background Thoracic esophageal squamous cell carcinoma patients with cervical lymph node metastasis have poor prognosis and less effective of first-line therapy. The PICC-1 study aimed to assess efficacy and safety of the pembrolizumab combined with chemotherapy for patients with cervical lymph node metastasis. Methods Preoperative therapy includes pembrolizumab, nab-paclitaxel and cisplatin every three weeks for 2 cycles. The surgery was performed 3-6 weeks after the completion of the preoperative neoadjuvant therapy. Three weeks after surgery, two periods of maintenance therapy were continued with pembrolizumab combined with chemotherapy. Then maintenance treatment was continued with pembrolizumab for a full year. The primary endpoint was the pathologic complete response (pCR) rate. The secondary endpoints included the R0 resection rate, the major pathological response (MPR), recurrence-free survival (RFS), overall survival (OS) and perioperative complications. Results As of December 31, 2023, 22 patients who met the criteria were enrolled. All 22 patients suffered from treatment-related AEs of any grade during the neoadjuvant treatment period. The majority of AEs were lymphopenia (72.7%), anemia (59.1%), neurotoxicity (77.3%), nausea/vomiting (77.3%) and leukopenia (40.9%). In 8 of the 22 patients (36.4%), grade III or higher AEs were observed. All the patients underwent thoraco-laparoscopic esophagectomy without intraoperative conversion to open surgery. R0 resection was achieved in 90.9% of patients (20/22). pCR and mPR were observed in 31.8% (7/22) and 13.6% (3/22) of the resected patients, respectively. No patient died postoperatively. Conclusions Esophagectomy after neoadjuvant immunochemotherapy is a promising radical treatment for thoracic esophageal squamous cell carcinoma patients with cervical lymph node metastasis. R0 resection was achieved in 90.9% of patients, and pCR was observed in 31.8% (7/22) of resected patients.