Clinical Evaluation of Immune Cell Therapy in Esophageal Cancer Resistant to Immunochemotherapy.

Background/aim: Immune checkpoint inhibitors (ICIs) have improved cancer therapy outcomes, but effective treatments for ICI-refractory patients remain limited. Our group has investigated αβT cell therapy, which is adoptive immunotherapy, to enhance ICI efficacy. A safety evaluation study conducted in 2017 (UMIN: 000028756) confirmed that αβT cell therapy combined with low-dose ICIs can be administered safely without immune-related adverse events (irAEs). Encouraged by these findings, we launched a clinical trial (jRCTc031190098~031190101) to assess its efficacy. Additionally, a case of renal pelvis cancer achieved complete remission after αβT cell therapy following ICI failure. Given reports showing prolonged PD-1 occupancy post-ICI administration, we hypothesized a similar synergistic effect in ICI-refractory cases.

Case report: Esophageal cancer in a 64-year-old woman progressed despite chemoradiation, chemotherapy, and nivolumab, metastasizing to the lymph nodes, lung, and liver. After standard treatment completion, she was referred to our hospital. She developed uveitis as an irAE, which was controlled with steroid drops. In February 2024, three months after nivolumab therapy, αβT cell therapy was initiated (six biweekly doses). No irAEs occurred, and computed tomography (CT) scans showed slight liver metastasis reduction. Flow cytometry revealed increased CD3⁺ and αβT cells, suggesting an enhanced immune response. The MUSCAT assay revealed increased levels of autoantibodies against DDX53, a tumor-associated antigen.

Conclusion: αβT cell therapy may enhance the immune response even in ICI-refractory cases. Its safety and potential efficacy warrant further investigation, and a clinical trial (jRCTc030220287) is ongoing to evaluate its role in ICI-refractory cancer.