Dramatic Responses of Recurrent Upper Urinary Tract Urothelial Carcinoma Harboring FGFR3 and TP53 Activating Mutations to Pembrolizumab in Combination with Erdafitinib: A Case Report

BACKGROUND: Upper tract urothelial carcinoma (UTUC) has a high recurrence rate and is likely refractory to systemic chemotherapy. The long-term outcomes and responses to immunotherapy and retreatment regimen after tumor recurrence for such cases had not yet been well-documented. CASE PRESENTATION: Here we report a unique case of long-term follow-up with a 67-year-old woman, who was diagnosed with advanced UTUC, received radical nephroureterectomy with bladder cuff, and was refractory to chemotherapy with cisplatin and gemcitabine. Positive PD-L1 expression and somatic mutation of Ser249Cys in FGFR3 were identified in the tumor tissue. The patient then received pembrolizumab monotherapy and achieved complete response (CR) after 6 cycles of treatment. She discontinued pembrolizumab treatment thereafter but remained in CR for 3 years and 7 months until the recurrence of tumor in the right mid-ureter. The patient was then retreated with a combination of pembrolizumab and erdafitinib, and achieved CR again after the third cycle of treatment. CONCLUSION: We reported here a rare case of UTUC with concurrent pathogenic mutations in FGFR3 and TP53 with positive PD-L1 expression. The patient archived exceptional therapeutic responses to PD-1 blockade treatment and retreatment with combination of pembrolizumab and erdafitinib. Our results provide new insight into the duration of immunotherapy and the retreatment strategy after tumor recurrence based on individual genomic profiles.