Efficacy and safety of PD-1 inhibitors combined with chemotherapy for the treatment of local recurrence at the primary tumor site of ESCC following definitive chemoradiotherapy or radiotherapy

Objective: Exploring the efficacy and safety of the combination of programmed cell death protein 1 (PD-1) inhibitors with chemotherapy for the treatment of local recurrence at the primary tumor site of esophageal squamous cell carcinoma (ESCC) following definitive chemoradiotherapy.

Methods: Seventy-six patients with local recurrence at the primary tumor site of ESCC following definitive chemoradiotherapy, who were treated at the Cancer Hospital Affiliated with Nanjing Medical University from January 2019 to January 2024. All patients received treatment with a PD-1 inhibitor combined with chemotherapy, and the short-term efficacy, long-term efficacy, and adverse reactions were observed. Univariate and multivariate Cox regression models were employed to identify the factors influencing overall survival (OS) and after-recurrence survival (ARS).

Results: Among the 76 patients, 7 achieved partial response, 35 had stable disease, and 34 experienced progressive disease. The objective response rate was 9.2% (7/76), and the disease control rate was 55.3% (42/76). With a median follow-up time of 23.1 months, 33 out of 76 patients died. The median survival time was 38.5 months (95% CI: 29.6-47.3 months); the 1-year, 2-year, and 3-year OS were 94.5%, 66.6%, and 51.7%, respectively. The median ARS was 14.7 months (95% CI: 10.4-19.1 months); the 6-month, 12-month, and 24-month ARS were 85.8%, 59.6%, and 25.7%, respectively. Univariate analysis showed that the initial radiation dose, the Eastern Cooperative Oncology Group (ECOG) performance status of patients after recurrence, the recurrence-free interval (RFI), and the approach to chemotherapy treatment following local esophageal recurrence were factors affecting OS and ARS (P＜0.05). Multivariate analysis showed that initial radiotherapy dose (HR=0.268, 95% CI: 0.100-0.720), the ECOG performance status after recurrence (HR=4.106, 95% CI: 1.228-13.728), and RFI (HR=0.248, 95% CI: 0.106-0.582) were independent prognostic factors for OS. Additionally, the initial radiation dose (HR=0.289, 95% CI: 0.098-0.853) and the ECOG performance status after recurrence (HR=5.143,95% CI:1.404-18.838) were independent prognostic factors for ARS. The incidence of treatment-related adverse-reactions was 85.5% (65/76). Grade 3 or higher treatment-related adverse reactions primarily included anemia in 4 cases, leukopenia in 8 cases, neutropenia in 9 cases, thrombocytopenia in 2 cases, liver function abnormalities in 4 cases, and elevated troponin T in 2 cases. There were no cases of treatment-related mortality.

Conclusions: The combination of PD-1 inhibitors with chemotherapy is safe and effective for local recurrence at the primary tumor site of ESCC following definitive chemoradiotherapy and can provide survival benefits for patients. This approach can be considered as a therapeutic option for local recurrence at the primary tumor site of ESCC following definitive chemoradiotherapy.