Cidara Therapeutics’ CD388 Cuts Flu Cases 76% in Phase 2b Trial

Cidara Therapeutics (Nasdaq: CDTX) filed an 8-K disclosing positive topline data from its randomized, double-blind, placebo-controlled Phase 2b NAVIGATE study of CD388 for the prevention of seasonal influenza in 18-64-year-old healthy, unvaccinated adults.

Rhea-AI Filing Summary

Cidara Therapeutics (Nasdaq: CDTX) filed an 8-K disclosing positive topline data from its randomized, double-blind, placebo-controlled Phase 2b NAVIGATE study of CD388 for the prevention of seasonal influenza in 18-64-year-old healthy, unvaccinated adults.

The trial’s primary endpoint was met across all three single-dose cohorts, delivering statistically significant prevention efficacy (PE): 57.7% at 150 mg, 61.3% at 300 mg and 76.1% at 450 mg versus a 2.8% infection rate in placebo. All secondary endpoints—including efficacy at ≥37.8 °C and ≥37.2 °C fever thresholds and durability to week 28—also achieved statistical significance. CD388 was well-tolerated; no drug-related serious adverse events or unexpected dose-limiting toxicities were observed, and injection-site reactions were comparable to placebo.

Cidara has requested an End-of-Phase 2 meeting with the FDA to review the data and discuss Phase 3 design and timing. Additional NAVIGATE results will be presented at scientific conferences later in 2025. Management will host a conference call and webcast on 23 June 2025; supporting slides are furnished as Exhibit 99.1.

Positive

• Phase 2b NAVIGATE trial met primary and all secondary endpoints, showing up to 76.1% prevention efficacy versus placebo (p < 0.0001).
• CD388 exhibited a clean safety profile with no drug-related serious adverse events or unexpected toxicities across all dose groups.
• Cidara submitted an End-of-Phase 2 FDA meeting request, advancing CD388 toward a Phase 3 pivotal study.

Negative

• None.

Insights

Event Analyst

TL;DR: Robust efficacy and clean safety data de-risk CD388, positioning CDTX for Phase 3 and potential strategic interest.

The filing signals a material clinical milestone. Prevention efficacy above 60% across doses—peaking at 76%—beats the historical bar set by standard flu vaccines in healthy adults and is clinically meaningful. The absence of serious safety signals mitigates one of the principal development risks for systemic antiviral prophylaxis. A prompt FDA End-of-Phase 2 meeting request indicates management’s intent to accelerate timelines; successful alignment could place Phase 3 enrollment in the 2025-26 flu season. These outcomes strengthen CDTX’s negotiating leverage for partnership or non-dilutive funding and could expand the drug’s addressable market beyond high-risk populations. Investors should monitor cash runway and Phase 3 trial size, but near-term sentiment is clearly positive.

Clinical Trials Specialist

TL;DR: Efficacy across fever thresholds confirmed; safety profile supports larger pivotal studies, but elderly data still absent.

The dataset is technically solid: randomized design, >470 evaluable subjects, and rigorous RT-PCR confirmation elevate reliability. PE confidence intervals remain wide at lower doses, yet the grouped 300 mg + 450 mg analysis (68.6% PE; p<0.0001) underpins dose-selection optionality. Duration of protection to week 28 addresses a key unmet need for long-season coverage. Importantly, the filing does not include immunogenicity correlates or data in adults >65, the group with highest flu morbidity; regulators may require these in Phase 3. Still, the clean tolerability profile—no dose-dependent adverse-event gradient—simplifies pivotal trial risk management. Overall, the clinical risk profile has improved, though commercial upside depends on replicating results in older and co-morbid populations.

8-K Event Classification

Item 8.01 — Other Events

1 item

Item 8.01 Other Events Other

Voluntary disclosure of events the company deems important to shareholders but not covered by other items.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What prevention efficacy did Cidara's CD388 achieve in the Phase 2b NAVIGATE trial?

The filing reports 57.7% (150 mg), 61.3% (300 mg) and 76.1% (450 mg) prevention efficacy against laboratory-confirmed influenza versus placebo.

Were there any serious adverse events related to CD388?

No drug-related serious adverse events were observed; safety and tolerability were comparable to placebo across all doses.

What are Cidara Therapeutics' next steps after the Phase 2b results?

Cidara has requested an End-of-Phase 2 meeting with the FDA to discuss Phase 3 design and aims to start the pivotal trial after regulatory feedback.

When and where will additional NAVIGATE data be presented?

The company expects to present further results at scientific conferences in 2025; exact venues were not specified in the filing.

What secondary fever thresholds were evaluated and what were the results?

At ≥37.8 °C, PE ranged 54.7%-76.1%; at ≥37.2 °C, PE ranged 46.5%-71.1%, all statistically significant versus placebo.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 06/23/2025 - 07:05 AM Learn about SEC filing dates

0001610618false00016106182025-06-232025-06-23

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): June 23, 2025

Cidara Therapeutics, Inc.

(Exact name of registrant as specified in its charter)

Delaware

001-36912

46-1537286

(State or Other Jurisdiction of Incorporation or Organization)

(Commission File Number)

(I.R.S. Employer Identification Number)

6310 Nancy Ridge Drive, Suite 101

San Diego, California 92121

(858) 752-6170

(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligations of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, Par Value $0.0001 Per Share

CDTX

The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01 Other Events.

On June 23, 2025, Cidara Therapeutics, Inc. (the “Company”) announced positive topline results from its randomized, double-blind, placebo-controlled Phase 2b NAVIGATE trial evaluating CD388 for the prevention of seasonal influenza in healthy unvaccinated adults aged 18 to 64. The study met its primary endpoint, demonstrating a statistically significant prevention efficacy (“PE”) for each of three dose groups in individuals who received a single dose of CD388 at the beginning of the flu season and were evaluated for laboratory and clinically confirmed influenza over 24 weeks. The study also met all secondary endpoints, including efficacy at 37.8 and 37.2 degree Celsius temperature thresholds, as well as maintenance of PE up to 28 weeks with statistical significance. Over the same period, CD388 was well-tolerated at all doses with no unexpected dose-limiting treatment-emergent adverse events observed.

Primary Efficacy Analyses:

						150 mg N= 11753 n (%)			300 mg N = 11923 n (%)			450 mg N = 11873 n (%)			Placebo N = 11723 n (%)
Primary Endpoint1			Number of Participants Protocol-Defined ILI2			14 (1.2%)			13 (1.1%)			8 (0.7%)			33 (2.8%)
			Prevention Efficacy			57.7%			61.3%			76.1%			–
			95% CI (%)			21.1, 78.9			27.0, 81.2			49.3, 89.9			–
			p-value			0.0050			0.0024			<0.0001			–
ILI, influenza like illness; CI, confidence interval 1.Statistical significance for grouped 300mg + 450mg dose groups was met (PE = 68.6%, p<0.0001), allowing testing of individual dose groups. 2.ILI event defined as central laboratory-confirmed RT-PCR+ influenza infection (nasopharyngeal swab), new onset of fever (oral temperature ≥38.0°C), and new onset of ≥2 respiratory symptoms (nasal congestion, sore throat, cough) or ≥1 respiratory symptom and ≥1 systemic symptom (headache, feeling feverish, body aches/pains, fatigue). 3.Sample size (N) indicates evaluable population at time of primary analysis data cut (April 30, 2025).

Key Secondary Endpoints:

						150 mg N= 11753 n (%)			300 mg N = 11923 n (%)			450 mg N = 11873 n (%)			Placebo N = 11723 n (%)
Secondary Endpoints			Number of Participants with ≥ 37.8 °C Temp1			15 (1.3%)			15 (1.3%)			8 (0.7%)			33 (2.8%)
			Prevention Efficacy			54.7%			55.3%			76.1%
			95% CI (%)			16.7, 77.4			18.0, 77.8			49.3, 89.9
			p-value			0.0084			0.0073			<0.0001
			Number of Participants with ≥ 37.2 °C Temp2			22 (1.9%)			21 (1.8%)			12 (1.0%)			41 (3.5%)
			Prevention Efficacy			46.5%			49.6%			71.1%
			95% CI (%)			10.2, 69.3			14.8, 71.9			45.8, 86.1
			p-value			0.0148			0.0083			<0.0001
ILI, influenza like illness; CI, confidence interval 1.CDC definition: ILI event defined as central laboratory-confirmed RT-PCR+ influenza infection (nasopharyngeal swab), new onset of fever (oral temperature ≥37.8°C), and new onset of ≥2 respiratory symptoms (nasal congestion, sore throat, cough). 2.ILI event defined as central laboratory-confirmed RT-PCR+ influenza infection (nasopharyngeal swab), new onset of fever (oral temperature ≥37.2°C), and new onset of ≥2 respiratory symptoms (nasal congestion, sore throat, cough) or ≥1 respiratory symptom and ≥1 systemic symptom (headache, feeling feverish, body aches/pains, fatigue). 3.Sample size (N) indicates evaluable population at time of primary analysis data cut (April 30, 2025).

Safety and tolerability data were similar in all arms with no safety signals observed. No drug-related serious adverse events were observed, and treatment-emergent adverse events showed no dose-dependent pattern between CD388 and placebo groups. Injection site reaction rates were similar across all CD388 dose groups and placebo.

The Company expects to present additional results from the NAVIGATE trial at upcoming scientific conferences in 2025.

The Company has submitted an end of Phase 2 meeting request to the U.S. Food and Drug Administration (the “FDA”) to review the Phase 2b results and further discuss the Phase 3 trial design and start time.

On June 23, 2025, the Company will host a conference call and webcast and present certain materials related to the Company (the “Presentation”). A copy of the Presentation is attached hereto as Exhibit 99.1 and incorporated herein by reference.

Forward-Looking Statements

This Current Report on Form 8-K contains forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995, including without limitation statements regarding potential benefits of and future plans for CD388, plans for engaging with the FDA and the impact of such discussions, a planned Phase 3 trial of CD388 and the expected timing for presenting additional results from the NAVIGATE trial. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “target,” “should,” “would,” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Actual results or events could differ materially from the plans, intentions and expectations disclosed in these forward-looking statements as a result of various important factors, including risks and uncertainties associated with the Company’s business and finances in general and those risks described under the caption “Risk Factors” in the Company’s Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2025, filed with the Securities and Exchange Commission (the “SEC”) on May 8, 2025 and other filings that the Company makes with the SEC in the future. Any forward-looking statements contained in this Current Report on Form 8-K speak only as of the date hereof, and the Company expressly disclaims any obligation to update any forward-looking statements, whether because of new information, future events or otherwise.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.						Description
99.1						Presentation Materials of Cidara Therapeutics, Inc.
104						Cover Page Interactive Data File (embedded within the Inline XBRL document).

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

			Cidara Therapeutics, Inc.
Date: June 23, 2025									/s/ Jeffrey Stein, Ph.D.
									Jeffrey Stein, Ph.D.
									President and Chief Executive Officer (Principal Executive Officer)