Efficacy of the 1<sup>st</sup> generation tyrosine kinase inhibitor sunitinib in the treatment of metastatic renal cell carcinoma in alternative dosing regimens

Abstract

Metastatic renal cell carcinoma accounts for almost 85% of all cases of malignant neoplasms of the kidney. Sunitinib is an anti-angiogenic tyrosine kinase inhibitor, one of the indications is the treatment of mRCC in adults. Sunitinib is an oral tyrosine kinase inhibitor that includes the vascular endothelial growth factor receptor (VEGFR) and the platelet-derived growth factor receptor (PDGFR). Sunitinib is primarily used as a first-line drug at an initial dose of 50 mg. 1 time per day for 4 weeks followed by a 2-week break. Recommendations, if dose modification is necessary, indicate a dose reduction to 37.5 mg per day and, if necessary, a further dose reduction to 25 mg per day. Another promising regimen is to continue the daily dose of 50 mg with more frequent breaks: 2 weeks of treatment followed by a pause of 1 week. The analysis presented in the article shows that patients with mRCC who switched to sunitinib 2/1 regimen due to adverse events from the standard 4/2 regimen do show an improved safety profile. There is evidence of a significant reduction in overall grade 3-4 toxicity, as well as a reduction in the incidence of specific drug toxicity such as fatigue, hypertension, hand and foot syndrome, and thrombocytopenia. The article presents a clinical observation of a patient with advanced renal cell carcinoma who has a contraindication for immunotherapy. The patient underwent cytoreductive laparoscopic resection of the left kidney. Taking into account the existing contraindications to immunotherapy, the patient was prescribed sunitinib monotherapy at the standard dosage in the first line. After two courses of therapy, due to adverse events, the therapy regimen was changed from 4/2 to 2/1. The ongoing therapy in the 2/1 regimen demonstrated a satisfactory safety profile with adequate clinical efficacy.