Rechallenge with immune checkpoint inhibitors for advanced esophageal squamous cell carcinoma

Despite the widespread use of immune checkpoint inhibitors (ICIs) in cancer treatment, disease progression remains common in the majority of patients and subsequent therapeutic options for this population are limited. ICI rechallenge has been validated favorably in terms of efficacy and safety in many cancer types, while data in esophageal squamous cell carcinoma (ESCC) are still lacking.

Clinical and pathological characteristics of advanced ESCC patients who received ICI rechallenge were collected retrospectively. The primary outcomes of interest were the disease control rate (DCR) and progression-free survival (PFS). Treatment-related adverse events were also recorded. We categorized patients into primary resistance and secondary resistance based on a 6-month disease control duration following the initial immunotherapy and further conducted exploratory analyses.

A retrospective cohort study spanning January 2018 and October 2023, at Peking University Cancer Hospital, scrutinized 45 advanced ESCC patients undergoing two lines of ICI-based therapies (ICI-1 and ICI-2). The initial therapeutic approach involved combining ICIs with chemotherapy, and the ICI rechallenge primarily comprised ICIs and angiogenesis inhibitors. The median PFS for ICI-1 was 6.7 months with a disease control rate of 88.9 %. Following the ICI rechallenge, the median PFS and disease control rate remained at 3.2 months and 73.3 %, respectively. It is noteworthy that patients with secondary resistance to ICI-1 exhibited a higher 6-month PFS rate (29.6 % v.s. 11.1 %) in the ICI-2 stage. Any grade of treatment-related adverse events was observed in 29 (64.4 %) and 18 (40.0 %) patients at ICI-1 and ICI-2. The incidence of treatment-related adverse events in grades 3-4 was 9.1 % at ICI-1 and 9.1 % at ICI-2.

ICI rechallenge may offer a potential survival benefit and a favorable safety profile for patients with ESCC who have progressed after initial immunotherapy. Patients exhibiting acquired resistance during initial immunotherapy are more likely to achieve prolonged disease control after undergoing rechallenge therapy. Prospective studies are required to further explore the optimal combined therapy and select targeted population.