Venous Thromboembolism and Bleeding with Temozolomide-, Bevacizumab-, and Nitrosourea-Based Therapy in Glioma: A Dual-Database Pharmacovigilance Study

<b>Introduction</b>: Patients with malignant glioma are inherently at high risk of venous thromboembolism (VTE) and bleeding, and systemic therapy may further modify this vascular risk. This study used large spontaneous reporting databases to compare VTE, central nervous system (CNS) bleeding and gastrointestinal (GI) bleeding signals associated with four representative systemic therapies for glioma-temozolomide, bevacizumab and the nitrosourea alkylating agents lomustine and carmustine-and explore bevacizumab-based combination regimens. <b>Methods</b>: We conducted a retrospective pharmacovigilance study using the FAERS and the CVARD, identifying reports of patients with gliomas exposed to temozolomide, bevacizumab, lomustine or carmustine. VTE, CNS bleeding and GI bleeding were defined a priori, and disproportionality was assessed using reporting odds ratios (RORs) with 95% confidence intervals (CIs); a positive signal was defined as a ≥ 3 and a 95% CI lower bound > 1. In bevacizumab-exposed patients, we compared bevacizumab monotherapy with bevacizumab + temozolomide and bevacizumab + lomustine treatments and performed sensitivity analyses on a stricter glioma cohort. <b>Results</b>: Bevacizumab was the only drug that consistently showed positive signals for VTE and GI bleeding, whereas temozolomide showed no clear VTE signal, and nitrosourea agents yielded only sparse, unstable increases. Bevacizumab + temozolomide regimens had higher RORs for VTE and GI bleeding than bevacizumab alone, while bevacizumab + lomustine showed only modest VTE increases and no robust bleeding signals. <b>Conclusions</b>: In real-world pharmacovigilance data, bevacizumab-containing therapy, particularly when combined with temozolomide, carries the greatest disproportionate burden of VTE and GI bleeding among common systemic treatments for malignant glioma, whereas temozolomide alone appears largely neutral, and current evidence supporting nitrosourea-related signals remains inconclusive.