Sustained Response to Anti-PD-1 Therapy in Combination with Nab-Paclitaxel in Metastatic Testicular Germ Cell Tumor Harboring the KRAS-G12V Mutation: A Case Report.

Introduction: Cisplatin-based standardized therapy has been established for metastatic testicular germ cell tumors (TGCTs). However, the patient prognosis is considerably less favorable if the disease recurs following failure of first-line therapies. There is a need for novel treatment options for patients with recurrent or metastatic TGCTs, notably for those that are not sensitive to first-line chemotherapy. With the development of next-generation sequencing technologies, an increasing number of gene mutations has been identified in TGCTs. Previously published research studies have established a link between KRAS mutations and chemotherapy resistance, and have demonstrated that KRAS mutations are associated with inflammatory tumor microenvironment and tumor immunogenicity, leading to an improved response to inhibition of programmed death (PD-1) protein expression. Previous studies have reported that the tumor immune microenvironment of TGCT influences therapeutic efficacy.

Case presentation: A 65-year-old metastatic patient with TGCT and a KRAS-12 valine-for-glycine gene mutation was described. This patient initially underwent inguinal orchiectomy and received two prior chemotherapeutic regimens. Following the rapid progression of the disease, the patient was treated with anti-PD-1 therapy and nab-paclitaxel chemotherapy, and his condition was successfully controlled by this combination treatment.

Conclusion: To the best of our knowledge, this is the first successful case of KRAS-mutation patient with TGCT who achieved partially and sustained disease remission by combining immune checkpoint inhibitors with chemotherapy. This case provides an excellent example for personalized treatment of metastatic TGCTs.