Yuka Takehara

and 8 more

Background Several good results of clinical trial of nivolumab or involving nivolumab in advanced esophageal squamous cell carcinoma were reported. However, the response rate was still poor. A rare phenomenon called the “abscopal effect” refers to the regression of not only the irradiated tumor but also non-irradiated distant tumors after local radiotherapy. The mechanism is not completely clear, but it is thought that the activation of anti-tumor immunity induced by radiotherapy is the main factor. Case A 66-year-old man with recurred and nivolumab resistant esophageal squamous cell carcinoma in left-side cervical and abdominal para-aortal lymph node metastasis was treated with a total of 40 Gy (10 fractions) of radiotherapy to the left-side cervical lymph node metastasis which caused neck pain as a palliative treatment. Nivolumab was resumed the day after completion of radiotherapy. At 3 months after radiotherapy showed that the irradiated lesion in the left neck had regressed to a scar-like appearance. Notably, the abdominal para-aortal lymph nodes outside the irradiation area, which had previously tended to progress, had also shrunk (abscopal effect). The T cell receptor and B cell receptor (TCR/BCR) repertoire analysis before and after radiotherapy revealed that radiotherapy caused the changes in the TCR/BCR repertoire. Conclusion Changes in the TCR/BCR receptor repertoire repertoires were assumed to be a part of the mechanism of the abscopal effect. The findings in this patient suggest that combination of immune checkpoint inhibitors and radiotherapy can be a promising treatment approach, even for patients with immune checkpoint inhibitors resistant cancer.