Sintilimab-Induced Diabetic Ketoacidosis in a Patient with Radiation and Multichemorefractory Penile Cancer: A Case Report and Literature Review

Penile squamous cell carcinoma (PSCC) is a rare disease. The treatment options for advanced penile cancer are often limited, and the prognosis remains poor. We reported a 52-year-old male recurrent and metastatic PSCC patient with high PD-L1 expression (90%) and TMB (14.4 muts/Mb). He had undergone penectomy, bilateral inguinal lymph node dissection, and excision of the abdominal wall mass. Despite cisplatin-based concurrent chemoradiotherapy and sequential chemotherapy with docetaxel plus cisplatin then being carried out, the carcinoma still progressed. The patient then obtained progression-free survival with continuous sintilimab, although he experienced the new onset of ICI-induced diabetes after 24 cycles of sintilimab and required sustained insulin treatment. He had negative type 1 diabetes-associated autoantibodies and the susceptible HLA genotype DR3-DQ2 haplotype. This is the first patient with radiation and multichemorefractory PSCC who has obtained the remarkable anti-tumor effect of partial regression exceeding 32 months during continuous sintilimab and anlotinib treatment.