PB0927 - Bleeding and thrombosis in patients receiving chimeric antigen receptor T-cell therapy

Background: Chimeric antigen receptor (CAR) T-cell therapy is established for patients with hematologic malignancies. Emerging toxicities associated with CAR T-cell therapy include systemic coagulopathy and potentially increased risk of bleeding and thrombosis.

Aims: We aimed to determine the rates of hemorrhagic and thrombotic events in patients receiving CAR T-cell therapy.

Methods: We performed a retrospective cohort study of patients with hematologic malignancies treated with CAR T-cell therapy at an academic center from 2016-22. Data was manually extracted from CAR T-cell administration through 180 days post-infusion. Bleeding and thrombotic events were reviewed and categorized based on ISTH criteria, stratified at 30 and 180 days. We calculated cumulative incidence and 95% confidence intervals (CI) for thrombotic and bleeding events at 30 and 180 days post-infusion, with death as a competing risk.

Results: The study cohort included 102 patients with a median age of 67 years. Primary malignancies included diffuse large B-cell lymphoma (55.9%) and multiple myeloma (25.5%). Of 99 patients who had coagulopathy testing, 77 (77.8%) developed prothrombin time prolongation and 54 (54.5%) developed partial thromboplastin time prolongation. Forty-eight of 95 patients (50.5%) developed hypofibrinogenemia. Cumulative incidence of thrombotic events at 30 days and 180 days post-infusion was 3.8% (95% CI: 0.2–7.4) and 5.7% (95% CI: 1.3–9.9), respectively. The cumulative incidence of bleeding events at 30 days and 180 days post-infusion was 4.8% (95% CI: 0.7–8.7) and 16.2% (95% CI: 9.7–22.2), respectively (Figure 1). Of the 7 thrombotic events during the 180-day study period, 5 were venous events. Four of the 20 bleeding events were categorized as major hemorrhage, including 2 intracranial bleeds (Table 1).

Conclusion(s): There are significant rates of thrombosis and bleeding following CAR T-cell therapy. Additional investigations are warranted to further characterize risk factors to aid clinical decision making for these patients.