Efficacy and Safety of REGN7508 for Primary Prophylaxis of Cancer-Associated Thrombosis in Patients with Solid Tumors Undergoing Cancer Treatment

The primary objective is to evaluate the efficacy of REGN7508, a monoclonal antibody targeting factor XI, compared to placebo in the prophylaxis of cancer-associated thrombosis in participants with solid tumors undergoing cancer treatment. Additionally, the study aims to assess the incidence of clinically important bleeding events. Secondary objectives include:

• Evaluation of efficacy regarding individual components of the primary endpoint.
• Assessment of safety, tolerability, and immunogenicity.

This clinical trial involves 536 patients diagnosed with malignant solid tumors that are locally advanced or metastatic. The study population includes both male and female participants within the age ranges of 18 to 44 and 45 to 64 years. Participants must have an Eastern Cooperative Oncology Group performance status of 0 to 2. Selection is based on a Khorana thromboembolic risk score of 2 or greater or the presence of a documented somatic genetic variant associated with an increased risk of venous thromboembolism. The primary objectives are:

• To evaluate the effect of REGN7508 compared to placebo in the prevention of cancer-associated thrombosis.
• To evaluate the effect of REGN7508 compared to placebo on clinically important bleeding events.

This Phase 3, multicenter, randomized, double-blind, placebo-controlled study is designed to evaluate the efficacy and safety of REGN7508, a monoclonal antibody targeting factor XI, for the primary prophylaxis of cancer-associated thrombosis in individuals with solid tumors undergoing cancer treatment. The investigation focuses on the time-to-first event of centrally adjudicated venous thromboembolism, including deep vein thrombosis, non-fatal pulmonary embolism, or arterial thromboembolism, as well as thromboembolism-related death. Additionally, the study assesses the impact on major bleeding events. The methodology involves a screening visit to confirm histological diagnosis and assess Khorana thromboembolic risk score or specific somatic genetic variants. Participants are assigned to receive either the investigational product or a placebo. The trial is expected to conclude by October 2029.

The experimental treatment consists of REGN7508, a monoclonal antibody targeting factor XI. The specific pharmaceutical form, dosage, and route of administration are not specified in the provided documentation.

The control group receives a placebo as part of a double-blind, placebo-controlled design to evaluate the prevention of cancer-associated thrombosis.

Efficacy is evaluated by comparing the effects of REGN7508 against a placebo in the prevention of cancer-associated thrombosis. The primary endpoint is the time-to-first event of centrally adjudicated venous thromboembolism, which includes deep vein thrombosis, non-fatal pulmonary embolism, arterial thromboembolism, or death related to thromboembolism or arterial thromboembolism. A second primary endpoint is the time-to-first event of major bleeding, as defined by the International Society of Thrombosis and Hemostasis, or clinically relevant non-major bleeding.

Secondary endpoints include:

• Time-to-first event of symptomatic or asymptomatic proximal deep vein thrombosis.
• Time-to-first event of symptomatic or asymptomatic non-fatal pulmonary embolism.
• Time-to-first event of any arterial thromboembolism.
• Time-to-first event of thromboembolism- or arterial thromboembolism-related death.