This study is researching 2 different experimental drugs called REGN7508 and REGN9933 (called "study drugs"). The study is focused on people who have a tube placed in a vein to receive treatment (called Peripherally Inserted Central Catheter [PICC]). Patients with PICCs have a higher risk of getting blood clots which can block the veins (this is called Venous Thromboembolism [VTE]) and lead to serious health problems or be life threatening.

The aim of the study is to see how well REGN7508 and REGN9933 prevent blood clots compared to placebo after PICC placement and to see if these medications cause certain types of bleeding.

The study is looking at several other research questions, including:

• What side effects may happen from taking the study drugs
• How much study drug is in the blood at different times
• Whether the body makes antibodies against the study drugs (which could make the drugs less effective or could lead to side effects)
• If the study drugs affect the ability of the blood to clot normally

Key Inclusion Criteria:

1. Is undergoing PICC placement for Intravenous (IV) administration of clinically indicated medications, including chemotherapy, antibiotics, TPN, and/or other indications as described in the protocol
2. Has Eastern Cooperative Oncology Group Performance (ECOG) Status ≤3 or equivalent functional status as described in the protocol
3. Has International Normalization Ratio (INR) and aPTT values no more than 25% above the upper limit as described in the protocol
4. Weighs at least 40 kg during the screening period

Key Exclusion Criteria:

1. Has a history of prior venous thrombosis in the arm and/or ipsilateral thoracic central veins in which the PICC is to be placed
2. Has acute leukemia, myelodysplastic syndrome, or primary and secondary myelofibrosis
3. Has unresected luminal gastrointestinal (GI) (including esophageal) or unresected genitourinary (GU) malignancy
4. Has current or history of known brain tumors or brain metastases
5. Has any major cardiovascular event within approximately the past 30 days prior to study administration
6. Pre-existing central venous catheter or indwelling spinal or epidural catheter during the screening period

Note: Other Protocol Defined Inclusion/ Exclusion Criteria Apply

All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.

When Regeneron has:

• received marketing authorization from major health authorities (e.g., FDA, European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), etc.) for the product and indication or has globally discontinued development of the product for all indications on or after April 2020 and has no plans for future development
• made the study results publicly available (e.g., scientific publication, scientific conference, clinical trial registry)
• the legal authority to share the data, and
• ensured the ability to protect participant privacy

Qualified researchers can submit a proposal for access to individual patient or aggregate level data from a Regeneron-sponsored clinical trial through Vivli. Regeneron's Independent Research Request Evaluation Criteria can be found at: https://www.regeneron.com/sites/default/files/Regeneron-External-Data-Sharing-Policy-and-Independent-Research-Request-Evaluation-Criteria.pdf