Active not recruitingPHASE2INTERVENTIONAL

A Study to Evaluate the Safety, Pharmacokinetics, and Occurrence of Anti-Drug Antibodies Following Annual Doses of CD388

This study is for healthy adults who have already received one dose of the experimental drug CD388 without any serious issues. It aims to find out if taking CD388 once a year for two years is safe. Researchers will closely watch for any side effects and see how the drug moves through your body. A key part of the study is to check if your body develops 'anti-drug antibodies' — these are substances your immune system might make against the drug, which could change how well it works or if it's still safe. Participants will receive two yearly doses and be monitored for 18 months, with the hope that those who tolerated it well before will continue to do so, and that immune reactions will remain low.

At a glance

Status

Active not recruiting

Phase

PHASE2

Sponsor

Cidara Therapeutics Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA)

Enrolment target

400

Start

29 Oct 2025

Estimated completion

01 Jul 2027

Healthy Participants

What is this study about?

This study is looking at a new drug called CD388. It's designed for healthy adults who have already taken one dose of CD388 in a previous study and didn't have any serious side effects. The main goal is to understand if taking this drug yearly for two years is safe and how your body continues to react to it over time. Think of it like seeing how a familiar journey feels if you take it regularly.

Researchers are particularly interested in whether your body starts to produce something called 'anti-drug antibodies'. These are natural reactions from your immune system that could, in some cases, make the drug less effective or potentially cause new side effects. By carefully monitoring participants for 18 months after two annual doses, the study aims to get a full picture of the drug's safety, how it's handled by the body, and if these antibodies become an issue.

This research is important because it helps scientists understand the long-term effects of CD388. If a new drug is going to be used, it's vital to know it's safe not just after one dose but also with repeated use. The study is built on the idea that if you tolerated CD388 well the first time, you're likely to continue to do so, and that your immune system won't overreact with repeated annual doses.

Key takeaways

This study is for healthy adults who previously tolerated CD388 well.
It tests the safety of taking CD388 yearly for two years.
Researchers will check for side effects and how the drug works in your body.
They also want to see if your body makes substances that fight the drug.
Participation lasts about two and a half years, including monitoring.

Who may be eligible?

This study is looking for healthy adults, aged 18 to 66 years old, who have previously taken part in a specific study (called CD388.SQ.2.05) and received one dose of CD388 (either 150 mg, 300 mg, or 450 mg) without any serious health problems after that dose.

To be considered, you must generally be in good health. This means you shouldn't have serious existing conditions like certain blood disorders, cancer (apart from non-melanoma skin cancer), kidney problems, ongoing heart or lung issues, or autoimmune diseases. You also shouldn't be at high risk for complications from flu infections, based on medical guidelines.

Women who could become pregnant must agree to use highly effective contraception throughout the study and for 40 weeks after their last study injection. Your body mass index (BMI) will also need to be 18 or higher. You must be willing to attend all study visits and follow the study rules.

Quick self-check

I am between 18 and 66 years old.
I have participated in study CD388.SQ.2.05 before and did not have serious side effects from CD388.
I am generally in good health and do not have certain serious medical conditions.
My BMI is 18 or higher.
If I am a woman who could become pregnant, I am willing to use reliable contraception.
I am willing and able to attend all study visits for about two and a half years.

This is a guide only — the research team will confirm whether you can take part.

What does participation involve?

If you decide to join this study, you will receive two doses of the CD388 injection, given once a year over two years. After receiving your second dose, you will continue to be monitored by the study team for a further 18 months. Throughout this period, you will have regular clinic visits where researchers will perform various checks. These include taking blood samples to measure how the drug behaves in your body and to see if you are developing those 'anti-drug antibodies'. They will also carefully watch for any side effects and monitor your overall health. The total duration of your involvement in the study, from your first dose to the end of follow-up, will be about two and a half years.

Potential risks and benefits

Participating in a study like this helps advance medical knowledge and could contribute to developing new treatments in the future. However, there's no guarantee the drug will directly benefit you, and you won't get to continue receiving the drug after the study ends. As with any medication, there are potential risks, including side effects from the drug or reactions at the injection site. There's also the chance your body could develop antibodies against the drug. All procedures in the study carry some risk, such as discomfort from blood draws. You have the right to withdraw from the study at any time, for any reason, without it affecting your medical care.

Locations (3)

Floridian Clinical Research
Miami Lakes, United States
Spartanburg Medical Research
Spartanburg, United States
hVIVO Serviced Limited
London, United Kingdom

Common questions

What is CD388?

CD388 is an experimental drug, meaning it's still being tested to understand its effects and safety. This study is part of that testing process.

Why do I need to have taken CD388 before?

This study specifically looks at continuing to give CD388 to people who have already received one dose and handled it well, to see its effects over a longer period.

What are 'anti-drug antibodies'?

These are substances your immune system might make against the drug. Researchers want to see if your body produces them and if they affect the drug's safety or how it works.

Will I get the flu vaccine during the study?

Yes, you generally can receive the flu vaccine before or during the study, with a few specific exceptions that the study team will explain.

How long will my involvement in the study last?

Your involvement in the study will last about two and a half years, including two yearly doses and 18 months of monitoring afterwards.