Immune checkpoint inhibitor-associated thrombosis in patients with bladder and kidney cancer: a study of the Spanish Society of Medical Oncology (SEOM) thrombosis and cancer group.

Purpose: Both venous and arterial thrombotic events (VTE/AT) can be associated with immune checkpoint inhibitors (ICI). However, there is a paucity of information apropos patients in routine clinical practice.

Methods/patients: Retrospective, multicenter study promoted by the Thrombosis and Cancer Section of the Spanish Society of Medical Oncology (SEOM). Individuals with kidney or bladder cancer who initiated ICI between 01/01/2015 and 12/31/2020 were recruited. Minimum follow-up was 6 months (except in cases of demise). The primary objective was to calculate the incidence of ICI-associated VTE/AT and secondary objectives included to analyze their impact on survival and identify variables predictive of VTE/AT.

Results: 210 patients with kidney cancer were enrolled. The incidence of VTE/AT during follow-up (median 13 months) was 5.7%. Median overall survival (OS) was relatively lower among subjects with VTE/AT (16 months, 95% CI 0.01-34.2 vs. 27 months, 95% CI 22.6-31.4; p = 0.43). Multivariate analysis failed to reveal predictive variables for developing VTE/ AT. 197 patients with bladder were enrolled. There was a 9.1% incidence rate of VTE/AT during follow-up (median 8 months). Median OS was somewhat higher in patients with VTE/AT (28 months, 95% CI 18.4-37.6 vs 25 months, 95% CI 20.7-29.3; p = 0.821). Serum albumin levels < 3.5 g/dl were predictive of VTE/ AT (p < 0.05).

Conclusions: There appears to be no association between developing VTE/AT and ICI use in patients with renal or bladder cancer. Serum albumin levels are a predictive factor in individuals with bladder cancer.