PB0960 - Thrombosis and Intracranial Hemorrhage in Patients with Metastatic Brain Tumors Treated with Immune Checkpoint Inhibitors

Background: Immune checkpoint inhibitors (ICI) have emerged as first-line treatments for several metastatic malignancies and are now recognized to have significant thrombotic risk. Patients with metastatic brain cancer are at increased risk of thrombosis and intracranial hemorrhage (ICH).

Aims: We aimed to estimate rates of thrombosis and ICH in patients with brain metastasis receiving ICIs.

Methods: This was a retrospective, IRB-approved single-center cohort study of patients with metastatic brain disease treated with ICIs from 2010 to 2020. The primary endpoints were thrombosis and ICH up to 12 months after initiating ICI. Thrombotic events included venous thromboembolism (VTE) or arterial thrombus confirmed with radiologic imaging and categorized by anatomic location. ICH was classified by a neuro-oncologist blinded to patient details. Fisher’s exact test was used to compare the incidence of thrombotic and bleeding between patients using or not using anticoagulants and/or antiplatelet agents at the time of ICI initiation.

Results: We included 74 patients with a median age of 64.8 years; 56.8% were female. Primary malignancies included non-small cell lung cancer (73.0%), melanoma (12.2%), small cell lung cancer (6.8%), and renal cell carcinoma (5.4%). The 12-month cumulative incidences of thrombosis and ICH were 11.5% (95% CI: 4.1–18.2) and 6.5% (95% CI: 0.8–11.9) respectively (Figure 1). The most common type of thrombosis was pulmonary embolism (44.4%), followed by upper extremity DVT (22.2%) (Table 1). Among patients not anticoagulated at ICI initiation, 15.3% experienced a thrombotic event compared to 0% of patients using anticoagulation (P=0.19). Conversely, the risk of ICH in patients on anticoagulation or antiplatelets at ICI initiation was higher, though not significantly so, than patients not on these therapies (12.5% vs. 2.4%; P=0.16).

Conclusion(s): Patients with brain metastases receiving ICI therapy are at significant risk of thrombosis and ICH. Clinicians need to consider these contrasting risks to optimize management.