Five locally advanced anal canal squamous carcinoma patients received 4 cycles of neoadjuvant PD-1 inhibitor toripalimab and Docetaxol and Cisplatin chemotherapy followed by concurrent immunoradiotherapy. Molecular testing revealed that PD-L1 expression (≥1%) in tumor and CD4/CD163 expression in tumor and paracancerous tissue were positively correlated with tumor shrinkage in the neoadjuvant treatment phase...Pretreatment PD-L1 expression is positively correlated with tumor response to PD-1 inhibitor toripalimab and chemotherapy.