Low-dose axitinib rechallenge with positive outcomes in a patient with metastatic renal cell carcinoma refractory to interferon α, sunitinib, axitinib, and nivolumab therapies: a case report

BACKGROUND: There is no established treatment after failure of proven therapies for patients with metastatic renal cell carcinoma. CASE PRESENTATION: A 66-year-old Japanese man with metastatic renal cell carcinoma became refractory to interferon α and sunitinib therapies. He started treatment with axitinib at 10 mg/day, and the dose was gradually tapered down to 4 mg/day because of intolerable adverse events. His metastatic lesions shrank; however, he could not continue due to the adverse events. He started fourth-line therapy with nivolumab; however, the metastatic lesions increased. Rechallenge with axitinib 4 mg/day was started, and the dose was reduced to 2 mg/day because of adverse events. Subsequently, the adverse events became controllable, and the metastatic lesions were maintained at reduced size. CONCLUSION: Therapeutic drug monitoring of axitinib could play an important role in the development of safe and effective therapeutic treatment and individualization of these medications.