Positive RSV Phase 2b topline results for zelicapavir at Enanta (ENTA)

Rhea-AI Filing Summary

Enanta Pharmaceuticals reported that it has positive topline results from a Phase 2b study of its drug candidate zelicapavir (formerly EDP-938) in high-risk adults with respiratory syncytial virus (RSV). This mid-stage trial focuses on adults who are more likely to develop serious RSV disease, so encouraging data at this stage can be important for deciding whether to move the program into later-stage studies.

To share more detail, the company prepared a slide deck titled “Phase 2b Study of Zelicapavir in High-Risk Adults: RSVHR Topline Results,” which is included as an exhibit to this report. The presentation is being furnished rather than filed, which limits how it is treated under certain securities law liability provisions, but it provides investors with an overview of the initial clinical findings for zelicapavir in RSV.

Positive

• Positive Phase 2b topline results for zelicapavir in high-risk adults with RSV indicate encouraging mid-stage clinical outcomes that can support progression to later-stage development.

Negative

• None.

Insights

Biopharma clinical development analyst

Positive Phase 2b topline RSV data supports ongoing development of zelicapavir.

Enanta states that topline results from its Phase 2b study of zelicapavir in high-risk adults with RSV are positive. Phase 2b is a key proof-of-concept stage where a company evaluates both safety and signals of efficacy in a more targeted patient group. Positive topline data at this point can support decisions to advance into larger and more expensive late-stage trials.

The study focuses on high-risk adults with RSV, a population where prevention and treatment options are limited and clinical need is significant. While this report does not include numerical efficacy or safety data, furnishing a dedicated presentation suggests multiple endpoints or subgroup findings are summarized for investors and clinicians.

The outcome for the program will depend on detailed results, regulatory feedback, and the design of any subsequent trials. Future disclosures in company materials referencing the “RSVHR Topline Results” presentation may clarify the strength and consistency of the effect seen with zelicapavir and how Enanta plans to structure later-phase development.

ENANTA PHARMACEUTICALS INC false 0001177648 0001177648 2025-09-29 2025-09-29

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): September 29, 2025

ENANTA PHARMACEUTICALS, INC.

(Exact name of Registrant as Specified in Its Charter)

Delaware		001-35839		04-3205099
(State or Other Jurisdiction of Incorporation)		(Commission File Number)		(IRS Employer Identification No.)
4 Kingsbury Avenue Watertown, Massachusetts				02472
(Address of Principal Executive Offices)				(Zip Code)

Registrant’s Telephone Number, Including Area Code: (617) 607-0800

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation 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 $0.01 per share		ENTA		Nasdaq Global Select Market

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 7.01 Regulation FD Disclosure.

On September 29, 2025, Enanta Pharmaceuticals, Inc. (“Enanta”) announced positive topline data from its Phase 2b high-risk adults study of zelicapavir (formerly EDP-938) for the treatment of respiratory syncytial virus (“RSV”). In connection with such data release, the Company compiled a presentation entitled “Phase 2b Study of Zelicapavir in High-Risk Adults: RSVHR Topline Results” (the “Presentation”) that includes the topline data from its Phase 2b high-risk adults study of zelicapavir for the treatment of RSV referenced above. A copy of the Presentation is furnished as Exhibit 99.1.

The information in Item 7.01 of this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in any such filing.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit Number		Exhibit Description
99.1		Slide presentation entitled “Phase 2b Study of Zelicapavir in High-Risk Adults: RSVHR Topline Results”
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.

Date: September 29, 2025				ENANTA PHARMACEUTICALS, INC.
				By:		/s/ Jay R. Luly, Ph.D.
						Jay R. Luly, Ph.D.
						President and Chief Executive Officer

FAQ

What did Enanta Pharmaceuticals (ENTA) announce in this 8-K?

Enanta announced positive topline data from a Phase 2b study of its RSV drug candidate zelicapavir (formerly EDP-938) in high-risk adults.

What is zelicapavir in Enanta Pharmaceuticals' pipeline?

Zelicapavir is Enanta’s investigational therapy for treating respiratory syncytial virus (RSV), and it has been studied in a Phase 2b trial in high-risk adult patients.

What stage of clinical development is Enanta's RSV drug in?

Enanta’s RSV candidate zelicapavir has completed a Phase 2b trial in high-risk adults, from which the company reports positive topline results.

How is Enanta sharing details of the zelicapavir Phase 2b RSV results?

Enanta prepared a slide deck titled “Phase 2b Study of Zelicapavir in High-Risk Adults: RSVHR Topline Results”, which is furnished as Exhibit 99.1 to the report.

Is the zelicapavir RSV topline data considered filed with the SEC?

The company states that the information in Item 7.01, including Exhibit 99.1, is furnished and not deemed filed under Section 18 of the Exchange Act.

What is the significance of Enanta studying RSV in high-risk adults?

The Phase 2b trial targets high-risk adults, a group more susceptible to serious RSV complications, making positive topline data in this population particularly important for clinical decision-making.