A Study of Annual Doses of MK-1406/CD388 in Healthy Adults (MK-1406-006/CD388.SQ.2.07)

A Phase 2, Open-Label, Long-Term Study to Evaluate the Safety, Pharmacokinetics, and Occurrence of Anti-Drug Antibodies in Healthy Participants Following Annual Doses of CD388, a Novel Long-Acting Antiviral Conjugate

The goal of this clinical study is to learn if giving repeated annual doses of MK-1406 (CD388) is safe and how the body reacts to it in healthy adults who have already received one dose without serious side effects. The study aims to determine if the body makes antibodies against MK-1406 after repeated doses, which might affect how the drug works or how safe it is, and to better understand the safety and tolerability of repeated doses. Participants will receive two doses of MK-1406 over two years and be monitored for 18 months. Researchers will check for immune responses against the drug, watch for any side effects, and measure how the drug behaves in the body over time. This study is based on the idea that people who tolerated MK-1406 well before will likely continue to tolerate it safely with repeated annual dosing, and that the risk of immune reactions will remain low.

This is a Phase 2, open-label, long-term study to evaluate the occurrence anti-drug antibodies (ADAs) directed to MK-1406 (CD388) following administration of 2 annual doses of MK-1406 in healthy participants during an 18-month period. All participants previously completed study CD388.SQ.2.05/MK-1406-004, having received a dose of the active drug without experiencing any serious adverse events (SAEs) during that study. This study will also evaluate the safety and tolerability of MK-1406 and the pharmacokinetics (PK) of MK-1406 following repeated annual dosing.

Inclusion Criteria:

The main inclusion criteria include but are not limited to the following:

• Be in stable health
• Has previously completed participation in study CD388.SQ.2.05/MK-1406-004, and received a subcutaneous (SC) CD388/MK-1406 dose of either 150 mg, 300 mg or 450 mg.

Exclusion Criteria:

The main exclusion criteria include but are not limited to the following:

• Have a contraindication to subcutaneous (SQ) injections and venipunctures (eg, bleeding disorders).
• Has a known or suspected allergy or history of anaphylaxis or other serious adverse events (SAEs) to zanamivir (following administration of inhaled or intravenous formulations), monoclonal antibodies, or any of the components of CD388/MK-1406.