Herrmann, Joerg

Background: Immune checkpoint inhibitors (ICIs) have transformed cancer therapy but may increase thrombotic risk through immune-mediated inflammation. While venous thromboembolism is a known complication in cancer, real-world data quantifying the incidence of pulmonary embolism (PE) and deep venous thrombosis (DVT) specifically in ICI-treated patients remain limited. Methods: We conducted a retrospective cohort study of cancer patients treated with ICIs at a tertiary institution from 2011 to 2022. Electronic health records were reviewed to identify cases of PE and DVT, along with baseline characteristics and clinical outcomes at one-year follow-up. Rates of PE and DVT were compared to those reported in the literature. Time-dependent Cox regression analyses were performed to assess associations of PE and DVT with one-year all-cause mortality and heart failure (HF), defined as a new diagnosis and/or HF exacerbation/hospitalization. Results: Among patients treated with ICI, the incidence of PE and DVT was 10.6% and 8.3%, respectively. These rates are higher than those reported in several prior studies, where PE incidence in patients treated with ICI typically ranged from 3% to 6% and DVT incidence from 3% to 5%. A history of valve disease, lung cancer, and treatment with pembrolizumab or durvalumab were more frequently observed among patients with PE, whereas pembrolizumab use was most prevalent among those who developed DVT. In time-dependent Cox regression analyses, PE was significantly associated with increased one-year all-cause mortality (HR: 2.62, 95% CI: 2.12–3.23, p < 0.001) and showed a trend toward increased HF (HR: 1.63, 95% CI: 0.96–2.75, p = 0.070). Similarly, DVT was also associated with significantly higher one-year all-cause mortality (HR: 2.63, 95% CI: 2.10–3.31, p < 0.001) and a significantly greater risk of HF (HR: 1.80, 95% CI: 1.03–3.15, p = 0.040). Conclusion: In this real-world cohort study, PE and DVT were more frequent than previously recognized in ICI-treated cancer patients and were associated with significantly increased risks of all-cause mortality and heart failure. Conditions such as valve disease, lung cancer, and specific ICI therapies (e.g., pembrolizumab or durvalumab) may help identify patients at higher thrombotic risk. These findings underscore the importance of vigilant thrombotic risk assessment and may support the need for proactive monitoring or prevention strategies in high-risk patients receiving ICI therapy.