LAUSR

Background: Immune checkpoint inhibitors with or without chemotherapy form the backbone of treatment for patients with advanced NSCLC without an actionable driver mutation. Emerging literature shows that ICIs increase the risk of venous thromboembolism (VTE), which is a major cause of death in patients with NSCLC. The mechanism is yet to be elucidated but is likely secondary to inflammation. Since chemotherapy is immunosuppressive, we sought to understand if the addition of chemotherapy to ICIs impacted the incidence of VTEs. Methods: We performed a retrospective cohort study to evaluate thromboembolic outcomes in patients diagnosed with advanced NSCLC between 2012 and 2018 and treated with either ICIs or chemo immunotherapy at Cleveland Clinic Foundation. Diagnosis of thrombotic events (TE) (arterial/deep vein thrombosis and/or pulmonary embolism) was confirmed by imaging. Overall survival (OS) was estimated by Kaplan-Meier and compared using log rank test. Odds of developing TE was estimated and compared between ICI and ChemoIO groups, using Fisher's Exact Test. Results: A total of 367 NSCLC patients (242 pts on ICI only and 125 pts on ChemoIO regimen), were identified with a median age 65 years ( range 58-72), 52% were men, 82% white, 85.3% smokers, 91.8% had ECOG ≤2, 73 % had adenocarcinoma and 18% had squamous cell carcinoma, 34% with brain metastasis and the distribution of PDL1expression was as follows- <1 (26.4%), 1-49% (48%) and ≥50% (25.6%). Adjusted response rates to treatment were (N, %): Complete Response (CR) (6/367, 1.9%), Partial Response (PR) (96/367, 30%), Stable Disease (SD) (76/367, 24%) and PD (143/367, 45%). TE was detected in 19% of the cohort (n=70) (8.4% DVT, 4.9% PE, 5.2 % both, and 0.5 % arterial TE. Rate of TE in NSCLC pts on ICI alone was 18% (44/242) Vs. 21% (26/125) for those on ChemoIO (OR 1.5, 95% CI 0.66-2.1, P 0.6). Development of TEs was not associated with survival differences with either regimen (P >0.05). Conclusion: Rates of TE were high in patients with advanced NSCLC who received ICI therapy, but no different if treated with ICIs alone or ChemoIO. Further studies to better understand the pathophysiology of TE in patients treated with ICIs might allow us to identify subgroups of patients that are at the highest risk for TEs. Citation Format: Doaa Attia, Ran Zhao, Alok A. Khorana, Prandya Patil. Risk of thromboembolism in patients with non-small lung cancer (NSCLC) treated with immune check point inhibitors (ICIs) versus chemoimmunotherapy (ChemoIO) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3217.