Venous thromboembolism incidence and risk assessment in lung cancer patients treated with immune checkpoint inhibitors

Background: There are scarce data on venous thromboembolism (VTE) rates among non-small cell lung cancer (NSCLC) patients treated with immune-checkpoint inhibitors (ICI). The Khorana Score (KS), used to guide thromboprophylaxis in cancer patients, was validated in patients receiving chemotherapy. Objective: To assess VTE rates and KS performance among NSCLC patients treated with ICI or chemotherapy. Methods: We performed a retrospective cohort study of NSCLC patients starting either ICI or platinum-based chemotherapy. The 6-month cumulative incidence of VTE in the ICI and chemotherapy cohorts and hazard ratios (HR) with 95% confidence intervals (CI) were calculated, using death as a competing risk. Subgroup analysis of low (0-1) and high (≥2) KS risk groups was performed. Results: The study included 345 NSCLC patients receiving single agent ICI (n = 176) or chemotherapy (n = 169). The 6-month cumulative incidence of VTE was 7.1% in the chemotherapy cohort and 4.5% in the ICI cohort (HR for chemotherapy = 1.6, 95% CI 0.66-3.9). Among chemotherapy treated patients, the high-risk KS group had a trend toward a higher VTE incidence, compared with patients with a low-risk KS (HR 3.04, 95% CI 0.82-11.22). Among ICI-treated patients, the high-risk KS group had a trend toward a lower VTE incidence compared with the low-risk group (HR 0.17, 95% CI 0.02-1.36). Conclusions: VTE rates were higher among NSCLC patients treated with platinum-based chemotherapy than those treated with ICI alone, though the precision of the relative estimate is low. The KS did not identify high-risk ICI-treated patients, suggesting that an ICI-specific risk model is warranted.