Usefulness of Biopsy Specimens for Evaluating CD103+Tumor-resident Memory T Cells in Esophageal Cancer

Background/Aim: CD103+ tissue-resident memory T cells (TRM) in tumor sites are associated with a favorable prognosis and predict the effectiveness of immune checkpoint inhibitors. The detection of CD103+ TRM infiltration in biopsy samples could be beneficial for patients without surgical indications. However, the usefulness of TRM detection in biopsy tissue and the difference in TRM status between biopsy and surgical specimens' post-neoadjuvant chemotherapy have not been elucidated. In the present study, we aimed to elucidate whether we can detect TRM in biopsy specimens and the impact of chemotherapy on TRM infiltration. Materials and Methods: Tissue sections were obtained from 46 patients with esophageal cancer who received neoadjuvant chemotherapy and underwent radical esophagectomy in 2017. Immunohistochemistry was performed using an anti-CD103 antibody for biopsy and surgical specimens. We examined the relationship between CD103 expression, clinicopathological features, and prognosis for each patient.Results: TRM infiltration was detected in the biopsy specimens. CD103 expression in biopsy specimens correlated with that in surgical specimens. Although there was no statistical significance in clinicopathological findings between CD103high and CD103low, patients with CD103high biopsy specimens exhibited favorable prognosis. The number of CD103+ cells was increased by chemotherapy: though with no survival benefit.Conclusion: Regardless of surgical indication, we were able to determine the TRM status even in biopsy specimens. CD103 evaluation at biopsy may be more useful and practical than evaluation in surgical specimens, enabling prediction of prognosis and response to immune therapy.