Cidara Therapeutics Announces Expanded and Accelerated Phase 3 Plan for CD388, a Non-Vaccine Preventative of Seasonal Influenza

- Update based on FDA End-of- Phase 2 meeting outcome

- Phase 3 study start accelerated by six months, in time for the fall 2025 Northern Hemisphere flu season

- A single Phase 3 trial of CD388, if successful, may be sufficient for BLA approval

- Phase 3 study population expanded to include adults over 65 years of age in addition to subjects with high-risk co-morbidities and immune compromised status

SAN DIEGO, Sept. 24, 2025 (GLOBE NEWSWIRE) -- Cidara Therapeutics, Inc. (Nasdaq: CDTX), a biotechnology company applying its proprietary Cloudbreak^® platform to develop drug-Fc conjugate (DFC) therapeutics, today announced updates to its planned Phase 3 registrational trial of CD388 following its End-of-Phase 2 (EOP2) meeting with the U.S. Food and Drug Administration (FDA). Cidara is proceeding with an expanded and accelerated development plan seeking biologics license application (BLA) approval based on a single Phase 3 study. Based on FDA feedback the study population will be expanded to include adults over 65 years of age with no specific co-morbidities in addition to subjects over 12 years of age with high-risk comorbidities or immune compromised status, substantially increasing the initial number of patients potentially eligible to receive CD388 from approximately 50 million to well over 100 million people in the U.S.

The planned Phase 3 study will be a global, multicenter, randomized, double-blind, placebo-controlled study to evaluate the safety and efficacy of a single 450-milligram dose of CD388 administered via subcutaneous injection at the beginning of the flu season. The company intends to begin enrollment by the end of September 2025 in the Northern Hemisphere with continuation into the spring of 2026 in the Southern Hemisphere, with a target enrollment of 6,000 subjects. This represents a six-month acceleration from the prior plan to initiate the Phase 3 study in the spring of 2026 in the Southern Hemisphere. The study will include an interim analysis following the Northern Hemisphere flu season, to assess the trial size and powering assumptions and determine enrollment for the Southern Hemisphere flu season.

“The FDA’s input on our Phase 3 study design was invaluable and we welcome the opportunity to expand the trial to include adults over 65 years of age who are among the most vulnerable to serious complications from influenza,” said Jeffrey Stein, Ph.D., president and chief executive officer of Cidara. “Older adults receive less protection from vaccines because the immune system naturally declines with age. Including them in our trial not only addresses a critical unmet need but will also accelerate enrollment. With the success of our financing earlier this summer, we believe that our planned Phase 3 development program will be fully funded through completion, and we look forward to building on the strong Phase 2b NAVIGATE results as we advance CD388 toward becoming a universal, non-vaccine, long-acting option for flu prevention.”

In Cidara’s planned Phase 3 study, participants will be randomized in a 1:1 ratio to receive either a 450-milligram dose of CD388 or placebo. The primary endpoint will be based on laboratory-confirmed influenza, body temperature ≥ 37.2°C (99°F), and new or worsening of either two respiratory symptoms (cough, sore throat, nasal congestion) or one respiratory symptom and one new systemic symptom (headache, fatigue, feeling feverish, or body aches).

About Cidara Therapeutics

Cidara Therapeutics is using its proprietary Cloudbreak^® platform to develop novel DFCs comprising targeted small molecules or peptides coupled to a proprietary human antibody fragment. Cidara’s lead DFC candidate, CD388, is a long-acting antiviral designed to achieve universal prevention of seasonal and pandemic influenza with a single dose by directly inhibiting viral proliferation. In June 2023, CD388 was granted Fast Track Designation by the FDA. Cidara announced positive top-line results from its Phase 2b NAVIGATE trial in June 2025. Additional DFCs have been developed for oncology and in July 2024 Cidara received investigational new drug application clearance for CBO421 which is intended to target CD73 in solid tumors. Cidara is headquartered in San Diego, California. For more information, please visit .

Forward-Looking Statements

This release contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and such forward-looking statements are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. “Forward-looking statements” describe future expectations, plans, results, or strategies and are generally preceded by words such as “anticipates,” “expect,” “intends,” “believes,” “may,” “plan” or “will”. Forward-looking statements in this release include, but are not limited to, statements related to the potential benefits of and future plans for CD388, the expected timing, study design and target enrollment for the planned Phase 3 registrational trial of CD388, the potential to obtain BLA approval based on a single Phase 3 clinical trial, the accelerated impact on enrollment of the expanded study design, and Cidara’s ability to fully fund the planned Phase 3 development program through completion. Such statements are subject to a multitude of risks and uncertainties that could cause future circumstances, events, or results to differ materially from those projected in the forward-looking statements, such as unanticipated delays in or negative results from Cidara’s clinical trials and other risks related to clinical development, delays in action by regulatory authorities, other obstacles associated with the enrollment of patients or other aspects of CD388 or other DFC development, having to use cash in ways other than as expected and other risks and uncertainties associated with Cidara’s business in general. These and other risks are identified under the caption “Risk Factors” in Cidara’s Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2025 and other filings subsequently made with the Securities and Exchange Commission. All forward-looking statements contained in this press release speak only as of the date on which they were made and are based on management’s assumptions and estimates as of such date. Cidara does not undertake any obligation to publicly update any forward-looking statements, whether as a result of the receipt of new information, the occurrence of future events or otherwise.

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