Prothena (NASDAQ: PRTA) files PRX012 Phase 1 ASCENT clinical update

Rhea-AI Filing Summary

Prothena Corporation plc filed a report stating that it issued a press release on August 27, 2025. The release provides an update on its PRX012 investigational drug and shares results from the Phase 1 ASCENT clinical program. The press release is included as Exhibit 99.1 and is incorporated by reference, meaning the detailed clinical information is contained in that exhibit rather than in this summary document.

PROTHENA CORP PUBLIC LTD CO false 0001559053 0001559053 2025-08-27 2025-08-27

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): August 27, 2025

PROTHENA CORPORATION PUBLIC LIMITED COMPANY

(Exact name of registrant as specified in its charter)

Ireland		001-35676		98-1111119
(State or other jurisdiction of incorporation)		(Commission File Number)		(I.R.S. Employer Identification Number)

77 Sir John Rogerson’s Quay, Block C

Grand Canal Docklands

Dublin 2, D02 VK60, Ireland

(Address of principal executive offices including Zip Code)

011-353-1-236-2500

(Registrant’s telephone number, including area code)

N/A

(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
Ordinary Shares, par value $0.01 per share		PRTA		The 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 8.01 Other Events.

On August 27, 2025, Prothena Corporation plc issued a press release announcing an update on its PRX012 investigational drug and results from the Phase 1 ASCENT clinical program. A copy of that press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits

(d) Exhibits

Exhibit No.		Description
99.1		Press Release dated August 27, 2025
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.

				PROTHENA CORPORATION PLC
Dated: August 27, 2025				By:		/s/ Tran B. Nguyen
				Name:		Tran B. Nguyen
				Title:		Chief Strategy Officer and Chief Financial Officer

FAQ

What did Prothena (PRTA) disclose in this 8-K filing?

Prothena disclosed that it issued a press release announcing an update on its PRX012 investigational drug and results from the Phase 1 ASCENT clinical program, attached as Exhibit 99.1.

Which Prothena drug is mentioned in the August 27, 2025 filing?

The filing refers to PRX012, described as an investigational drug, with an update and Phase 1 ASCENT clinical program results discussed in the attached press release.

What clinical program for PRX012 is referenced by Prothena (PRTA)?

Prothena references the Phase 1 ASCENT clinical program for PRX012 and notes that results from this program are included in the press release filed as Exhibit 99.1.

When did Prothena issue the PRX012 Phase 1 ASCENT update?

Prothena issued the press release providing the PRX012 Phase 1 ASCENT update on August 27, 2025.

Where can investors find details of Prothena’s PRX012 Phase 1 results?

Detailed information is in the press release attached as Exhibit 99.1 to the report, which is incorporated by reference.

Who signed the Prothena (PRTA) 8-K related to PRX012?

The report was signed on behalf of Prothena Corporation plc by Tran B. Nguyen, Chief Strategy Officer and Chief Financial Officer.