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Cidara Therapeutics Announces Promising Interim Phase 2a Data Assessing the Safety and Efficacy of a Single Dose of CD388 in an Influenza Challenge Model

By March 1, 2023No Comments
  • A single dose of CD388 decreased influenza viral replication in the upper respiratory tract and lowered influenza incidence rate in a human challenge model when compared to placebo
  • CD388 was generally safe and well tolerated with no adverse events related to study drug reported as of the February 13, 2023 data cut-off
  • Ongoing study being conducted in collaboration with Janssen

SAN DIEGO, March 01, 2023 — Cidara Therapeutics, Inc. (NASDAQ: CDTX), a biotechnology company developing long-acting therapeutics designed to help improve the standard of care for patients facing serious diseases, today announced promising efficacy and safety data from a planned interim analysis of the ongoing Phase 2a trial evaluating the pre-exposure prophylactic activity of CD388 against the H3N2 influenza A virus strain, as of a February 13, 2023 data cut-off. As evidenced by animal efficacy studies, CD388 has the potential to be a long-acting antiviral drug designed to deliver universal prevention of seasonal and pandemic influenza A and B strains. 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.

“This planned interim analysis of our Phase 2a study provides preliminary evidence that CD388 may effectively prevent influenza and supports our belief in the potential of DFCs from our Cloudbreak platform,” said Jeffrey Stein, President and CEO of Cidara Therapeutics. “We are pleased with these interim data and the productive collaboration between the Cidara and Janssen teams and look forward to the availability of final top-line results from this important trial.”

The interim analysis is based on 56 subjects, with 28 receiving a single dose of CD388 (150 mg) and 28 receiving a placebo. The interim data for the primary outcome measure of Area Under the Viral Load-Time Curve (VL-AUC) and for the infection incidence for CD388 versus placebo are shown below in Table 1.

Table 1.

Placebo (n=28) CD388 (n=28)
Area Under the Viral Load-time Curve (VL-AUC)- Mean (SD) 16.1 (11.9) 10.7 (8.0)
PCR confirmed influenza infection– n (%) 14 (50%) 6 (21.4%)

As shown in Table 1, despite the small sample size in this planned interim analysis, a decrease in viral replication in the upper respiratory tract and influenza infection was observed in participants receiving a single dose of CD388 when compared to placebo.

Treatment with CD388 was generally well-tolerated as of the February 13, 2023 data cut-off, with no treatment emergent adverse events leading to study discontinuation or serious adverse events reported in the interim analysis. These promising data establish preliminary clinical proof of concept for the ongoing CD388 development program.

The Phase 2a trial (NCT05523089) is a single-center, randomized, double-blind influenza challenge study in healthy volunteers designed to assess the prophylactic antiviral activity, safety, tolerability and pharmacokinetics of CD388 in healthy volunteers. All participants received either CD388 or placebo and were then challenged with influenza five days later.

About Cloudbreak® DFCs
Cidara is developing a new generation of immunotherapeutic agents from its Cloudbreak platform that couple targeted small molecule and peptide drugs to a human antibody fragment (Fc). These highly potent, long-acting drug-Fc conjugates (DFCs) are designed to inhibit specific disease targets while simultaneously engaging the immune system. In addition to multiple oncology programs, Cidara is advancing its antiviral DFC CD388 through Phase 1 (NCT05285137 and NCT05619536) and Phase 2a (NCT05523089) clinical trials in partnership with Janssen for the universal prevention and treatment of influenza. Cidara is also advancing DFC programs to target other life-threatening viruses, such as SARS-CoV-2.

About Cidara Therapeutics
Cidara is developing long-acting therapeutics designed to help improve the standard of care for patients facing serious diseases. The Company’s portfolio is comprised of new approaches aimed at transforming existing treatment and prevention 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, California. For more information, please visit

About Influenza
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 children, older people and people with certain health conditions, at higher risk for complications.1 While today’s flu vaccines are credited with significant public health benefits and currently offer the best defense against infection, vaccines have only been effective in about 29-39% of people over the past five years in the United States.2 Every year across the globe, there are an estimated 1 billion cases of influenza, resulting in 290,000 to 650,000 influenza-related respiratory deaths.3

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 “expect,” “potential,” or “goal.” Forward-looking statements in this release include, but are not limited to, statements related to the potential for influenza DFCs, including CD388, to prevent influenza by providing universal protection against all influenza strains for an entire season, the potential for CD388 to be an effective, long-acting antiviral drug, and whether the preliminary data presented in the interim analysis of the Phase 2a trial will be consistent with the full data set once the trial is complete. 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 preclinical or clinical trials, delays in action by regulatory authorities due to limitations on inspections and other COVID-19-related effects, and impacts of global and macroeconomic events, including the COVID-19 pandemic, supply chain disruptions and other obstacles on the enrollment of patients or other aspects of CD388 development. These and other risks are identified under the caption “Risk Factors” in Cidara’s most recent Quarterly Report on Form 10-Q 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.

Brian Ritchie
LifeSci Advisors
(212) 915-2578

Patrick Bursey
LifeSci Communications
(203) 430-9545

  1. About Flu. Centers for Disease Control and Prevention. Available at: Last accessed February 2023.
  2. Past Seasons’ Vaccine Effectiveness Estimates. Centers for Disease Control and Prevention. Available at: Last accessed February 2023.
  3. WHO launches new global influenza strategy. World Health Organization. Available at: Last accessed February 2023.

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