The correlation between the incidence of adverse events and progression-free survival in patients treated with cabozantinib for metastatic renal cell carcinoma (mRCC)

Clinical practice shows significant differences in treatment outcomes across patients treated with cabozantinib for metastatic renal cell carcinoma (mRCC). It is not known whether cabozantinib-induced adverse events are predictive factors of survival as in case of drugs such as sunitinib or axitinib. The study participants were 30 adult patients with mRCC treated with cabozantinib as a second- or further line setting. All adverse events were evaluated using the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0. Progression-free survival (PFS) values were calculated by taking the beginning of cabozantinib treatment as the start date and either disease progression or death as the end date. PFS were estimated using the Kaplan–Meier method, and compared using the log-rank test. We identified independent PFS predictors using multiple Cox proportional hazards models and reported hazard ratios (HR) with 95% confidence intervals. The median observation time cabozantinib treatment was 7.5 months, with a range of 2–15 months. During that time, 11 (37%) of the patients had mRCC progression. Median PFS on cabozantinib was not reached, and lower quartile was 6 months. All patients developed at least one adverse event in the course of cabozantinib therapy. Hypertension, hypothyroidism and HFS were observed most frequently, in about two-thirds of the patients. The co-incidence of multiple adverse events was common. Hypertension, hypothyroidism, diarrhea and liver toxicity were significantly associated with longer PFS values. Patients with three or more side effects had significantly longer PFS than those with two or fewer. Even though this study was conducted in a small patient sample and the observation time was relatively short our results confirm the predictive value of the incidence of adverse events during cabozantinib treatment in mRCC patients. To the best of our knowledge, this is the first study of this kind conducted in this group of patients.