Cabozantinib-induced serum creatine kinase elevation and rhabdomyolysis: a retrospective case series

Rhabdomyolysis, which is primarily characterized by serum creatine kinase (CK) elevation, is a potentially fatal disease, and it can occur in a variety of etiologies, including drug-induced. Cabozantinib is one of the standard treatments for patients with renal cell carcinoma (RCC). This retrospective case series aimed to investigate the frequency of cabozantinib-induced CK elevation and rhabdomyolysis, and to reveal their detailed clinical features.

To investigate the frequency of cabozantinib-induced serum CK elevation and rhabdomyolysis, we retrospectively reviewed the clinical information and laboratory data of the patients with advanced RCC who received cabozantinib monotherapy at our institution from April 2020 to April 2023. Data were retrieved from the electronic medical records and the RCC database of our institution. Primary endpoint of the current case series was the frequency of CK elevation and rhabdomyolysis.

Sixteen patients were retrieved form the database and 13 were included in the case series (excluded by clinical trial enrollment [n = 2] and short-term administration [n = 1]). Eight (61.5%) patients among them experienced serum CK elevation, including five patients who were classified into grade 1. CK elevation occurred a median of 14 days after initiation of cabozantinib. Two patients with grade 2 or 3 of CK elevation developed rhabdomyolysis with muscle weakness and/or acute kidney injury.

CK elevation may frequently happen during cabozantinib treatment, and in most cases, it may be asymptomatic and may not be clinically problematic. However, medical providers should be aware that symptomatic CK elevations suggestive of rhabdomyolysis may occasionally occur.