Metastatic renal cell carcinoma (mRCC) is associated with a high risk of thromboembolism (TE).
We investigated whether immunotherapy (IO) increases the hypercoagulable state in this high-risk population.
Patients with mRCC treated with IO between 1 January 2015 and 31 December 2019 at the Cleveland Clinic were identified. Cumulative incidence analysis calculated TE rates over time and Gray’s test determined differences in TE rates among groups. The Kaplan-Meier method estimated survival, while Cox proportional hazard regression evaluated the impact of TE on OS.
Of 351 patients, 75% were men with clear cell mRCC (81%) and International Metastatic Renal Cell Carcinoma (IMDC) intermediate- to poor-risk disease (77%). Patients received single-agent IO (52%), doublet IO (31%), or IO with non-IO therapy (17%). The median number of IO doses was 8 (range 1-81). At a median follow-up of 12.8 months, 12% of patients (n = 43) had a TE event (venous n = 37 [11%], arterial n = 6 [2%]). The cumulative TE incidence at 6 months was 4.4% (95% confidence interval [CI] 2.6-6.9) and 9.8% (95% CI 6.8-13.4) at 12 months. No factors, including IMDC or Khorana score, were identified to predict TE development. Seventy-two percent of TE resulted in hospitalization (9% TE-related mortality and 21% TE-related dose delay). TE (p < 0.0001), poor IMDC score (p < 0.0001), and Khorana score ≥ 2 (p < 0.0001) were associated with worse OS.
Patients with mRCC treated with IO had a high incidence of TE. TE was associated with risk of treatment delay, hospitalization, and mortality, while TE, IMDC poor risk, and Khorana score ≥ 2 were associated with worse survival. Further investigations into IO-associated TE are needed to identify benefit from primary thromboprophylaxis.

© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.