High-dose chemotherapy sensitizes locally advanced esophageal squamous cell carcinoma to PD-1 blockade for a higher pathological complete response rate and survival

PD-1 inhibitor and chemotherapy demonstrated durable antitumor activity with a manageable safety profile as the first-line treatment in patients with advanced esophageal squamous cell carcinoma (ESCC). The present study aimed to evaluate the efficacy of PD-1 inhibitors plus different dose intensity neoadjuvant chemotherapy in the treatment of locally advanced ESCC.Patients with locally advanced but resectable thoracic ESCC, staged as T3 or T4a, N0-3, and M0 or M1 lymph node metastasis (confined to the supraclavicular lymph nodes), were enrolled in this study. The eligible patients received tislelizumab plus different dose intensity chemotherapy for a 21-day cycle with repeated 2-4 cycles before surgery. The primary endpoints are pathological complete response (pCR) and major pathological response (MPR), and the secondary endpoints are objective response rate (ORR), disease control rate (DCR), and disease-free survival (DFS).From November 2019 to February 2022, 122 cases received at least two cycles neoadjuvant chemoimmunotherapy and were evaluated by imaging examination. Subsequently, 99 patients underwent surgery and were evaluated by pathological evaluation. According to chemotherapy dose intensity, the patients were divided into three cohorts: cohort 1 (<80% dose intensity), cohort 2 (80-90% dose intensity), cohort 3 (90-100% dose intensity). All surgery patients underwent minimally invasive esophagectomy (MIE). The average pCR was identified in 22.22%; 16% had pCR in cohort 1, 17.65% had pCR in cohort 2, and 30.00% had pCR in cohort 3. MPR was observed in 9 (36.00%) patients in cohort 1, 18 (52.94%) patients in cohort 2, 22 (55.00%) patients in cohort 3. In univariable and multivariable analysis, dose intensity was significantly associated with MPR (p = 0.048) in patients who underwent esophagectomy. For surviving patients, the median follow-up was 13.76 months after esophagectomy. Compared to cohort 1, cohorts 2 and 3 had better DFS (p = 0.056). In addition, the prognosis of patients with MPR was better than that of patients without MPR (p = 0.014).The robust antitumor activity of neoadjuvant chemoimmunotherapy for locally advanced but resectable thoracic ESCC was confirmed. More than 80% of chemotherapy dose intensity combined with immunotherapy resulted in a high pCR rate and prolonged DFS.