Cidara Therapeutics Announces Initiation of Phase 2a Human Viral Challenge Trial to Evaluate CD388 for Universal Prevention of Influenza

Cidara Therapeutics, Inc. recently announced the initiation of its Phase 2a trial to evaluate the pre-exposure prophylactic activity of CD388 against influenza virus. CD388 is a highly potent, long-acting antiviral designed to deliver universal prevention of seasonal and pandemic influenza. The study is being conducted under an exclusive worldwide license and collaboration agreement with Janssen Pharmaceuticals, Inc. (Janssen), one of the Janssen Pharmaceutical Companies of Johnson & Johnson, to develop and commercialize Cidara’s Cloudbreak drug-Fc conjugates (DFCs) for the prevention of seasonal and pandemic influenza.

The Phase 2a trial (NCT05523089), which dosed its first healthy volunteer on September 10th, is a single-center, randomized, double-blind, placebo-controlled, proof-of-concept study to assess the prophylactic antiviral activity, safety, tolerability and pharmacokinetics of CD388 against influenza via a human viral challenge (influenza) model, and to explore the impact of dose levels on efficacy. Multiple dose levels of CD388 will be evaluated in volunteers who will receive a single administration of CD388 or placebo prior to influenza viral challenge. The trial is expected to enroll up to 168 healthy adults.

“The initiation of this Phase 2a trial is an important milestone, as it represents the first study in which CD388’s prophylactic potential against influenza will be examined in humans,” said Jeffrey Stein, PhD, President and Chief Executive Officer of Cidara. “Because of its mode of action, CD388 has the potential to enable universal influenza coverage against all viral strains for all people, including those with compromised immune systems. We look forward to announcing the findings next year, and continuing our collaboration with Janssen who will be spearheading late-stage development.”

Cidara’s Cloudbreak DFCs, which stably couple highly potent small molecules or peptides to a proprietary composition of a human antibody fragment (Fc), is a fundamentally novel approach to treat and prevent serious viral infections and cancers. For influenza, the long-acting CD388 DFC is designed to directly inhibit viral proliferation by targeting a conserved region on the viral envelope, potentially conferring universal prevention of Types A and B influenza with a single seasonal dose.

Cidara is developing a new generation of immunotherapeutic antivirals from its Cloudbreak platform that couple potent antivirals to a human antibody fragment (Fc). These highly potent, long-acting, drug-Fc conjugates (DFCs) directly inhibit viral proliferation while simultaneously engaging the immune system. In addition to the clinical-stage CD388 program for seasonal and pandemic influenza, Cidara is advancing DFC programs to target other life-threatening viruses, such as SARS-CoV-2, as well as immuno-oncology targets associated with multiple cancers.

Influenza (“the flu”) is a contagious viral infection that can cause mild to severe illness, sometimes resulting in death. It’s caused by influenza viruses that infect the nose, throat and lungs, and can put people, such as older people, children, and people with certain health conditions, at higher risk for complications. While today’s flu vaccines are credited with significant public health benefits and currently offer the best defense against infection, only about 48% of U.S. adults received a vaccine during the 2019–2020 influenza season. Every year, there are an estimated 1 billion cases of influenza, resulting in 290,000 to 650,000 influenza-related respiratory deaths.

Cidara is developing long-acting therapeutics designed to improve the standard of care for patients facing serious diseases. The company’s portfolio is comprised of new approaches aimed at transforming existing prevention and treatment paradigms, first with its lead Phase 3 antifungal candidate, rezafungin, in addition to drug-Fc conjugates (DFCs) targeting viral and oncology diseases from Cidara’s proprietary Cloudbreak platform. Cidara is headquartered in San Diego, CA. For more information, visit