Hyperlipidemia and hypothyroidism among metastatic renal cell carcinoma patients taking sunitinib malate. Related or unrelated adverse events?

Background: In recent years, new-onset hypothyroidism was extensively reported in patients receiving sunitinib for malignancy. Effects of sunitinib on serum lipids are not described, however a hyperlipidemic state is commonly observed in hypothyroid patients. Here we report about the incidence and severity of hypercholesterolemia and hypertriglyceridemia in a cohort of patients receiving sunitinib for metastatic renal cell carcinoma.

Patients And Methods: Thyroid function tests, serum triglycerides, and cholesterol were prospectively evaluated in 39 consecutive metastatic renal cell carcinoma patients, who were receiving sunitinib as a first-line treatment. Incidence of hyperlipidemia, thyroid function impairment, and their possible relationship were investigated.

Results: Thyroid function tests, serum cholesterol, and triglycerides were assessed at baseline and before the beginning of each sunitinib cycle. During treatment, median triglyceride levels increased up to 271.3 mg/dL, and median cholesterol increased up to 234.7 mg/dL (+113% and +22%, respectively). A hyperlipidemic state developed in 27 patients (69.2%) within a mean time of 1.8 six-week cycles (range, 1-5 cycles) and persisted during treatment. Hypothyroidism was observed in 20 patients (51.2%) and usually developed within 2.3 cycles. Because hypothyroidism and hyperlipidemia developed at different time points of treatment and among different patients, our results failed to demonstrate a correlation between these adverse events.

Conclusion: New-onset hyperlipidemia was observed in an increased percentage of patients taking sunitinib. The mechanism of this side effect is still unclear. We recommend careful monitoring of serum lipid levels during sunitinib administration to recognize possible consequences, especially on cardiovascular health.