Association of immune checkpoint inhibitors (ICI) and venous thromboembolism (VTE): A single healthcare system experience.

Abstract

e14567 Background: Cancer and some anti-cancer therapies increase risk of VTE. ICIs cause immune activation and inflammation which are known to potentiate VTE formation. The risk of VTE associated with ICI is unclear, with conflicting evidence of association. Our study assessed the risk of VTE in patients treated with ICI compared to those receiving other cancer treatments. Methods: EPIC Slicer Dicer was used to collect data from three university-affiliated hospitals in New Orleans, LA. All patients >17 years of age, with an oncology treatment plan (TP) between January 1 2012 – January 31 2021 were considered the base population (n=6,894) for the study. The base population was divided into two cohorts - those that received ICI (n=794) versus those who did not (n=6,100). ICIs included pembrolizumab, nivolumab, avelumab, atezolizumab, durvalumab, cemiplimab, ipilimumab. An encounter diagnosis of deep venous thrombosis (DVT) or pulmonary embolism (PE) which was preceded by a TP in the last 1 year was used to identify patients with VTE after initiation of a TP. Categorical covariates compared across VTE groups using Chi-squared tests of independence. Two sample t-tests were used to compare continuous covariates based on VTE status. Logistic regression used to predict VTE as a function of ICIs and other potential confounders including age, BMI, gender, race and cancer subtypes. Results: Patients who experienced VTE were significantly more likely to have received ICI (1.43 times odds of VTE (95% CI = 1.12-1.83; p <0.005), be black or African American (p < 0.05 compared with White and Asian races), and have GI cancer (1.82 times odds, 95% CI= 1.41 – 2.36, p< 0.001), GU cancer (1.7 times odds, 95% CI = 1.3 – 2.23; p<0.001). Patients with VTE were significantly less likely to have breast cancer or other cancer types. Males had a decreased odd of VTE (0.73 odds, 95% CI= 0.62 – 0.85, p< 0.001). Conclusions: Based on the above results, there appears to be an increased likelihood of VTE in patients that receive ICI when compared to other types of cancer treatment. This study is a preliminary analysis and has limitations. At this time, it is unclear if prophylactic anticoagulation can reduce risk of VTE after ICI initiation. Further investigation is warranted in the form of individual chart review, or a prospective study.