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): November 46, 2025

RHYTHM PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

Delaware		001-38223		46-2159271
(State or other jurisdiction of incorporation)		(Commission File Number)		(IRS Employer Identification Number)

222 Berkeley Street

12th Floor

Boston, MA 02116

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (857) 264-4280

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
Common Stock, $0.001 par value per share	RYTM	The Nasdaq Stock Market LLC (Nasdaq Global 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 27.0201. ~~Results~~Regulation ofFD ~~Operations and Financial Condition~~Disclosure.

On November 47, 2025, Rhythm Pharmaceuticals, Inc. (the “Company”) ~~announced~~issued ~~its~~a ~~financial~~press ~~results~~release ~~for~~and ~~the~~published ~~third~~a ~~quarter~~presentation ~~ended~~in ~~September~~connection ~~30,~~with ~~2025.~~the ~~The~~matters ~~full~~disclosed ~~text~~in ofItem ~~the~~8.01 ~~press~~of ~~release~~this ~~issued~~Current byReport ~~the~~on ~~Company~~Form in8-K. ~~connection~~A ~~with~~copy of the ~~announcement~~related press release and presentation is furnished as Exhibit 99.1 and Exhibit 99.2, respectively, to this Current Report on Form 8-K ~~(the “Current Report”)~~.

The information contained in Item 27.0201 of this Current Report on Form 8-K (including ~~Exhibit~~Exhibits 99.1 and 99.2 attached hereto) shall not be deemed “filed” for purposes of Section 18 of the Securities 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 (the “Securities Act”), or the Exchange Act, except as expressly provided by specific reference in such a filing.

Item 8.01. Other Events.

On November 6, 2025, the U.S. Food and Drug Administration notified the Company that the Prescription Drug User Fee Act (“PDUFA”) goal date for the supplemental New Drug Application for IMCIVREE® (setmelanotide) for the treatment of acquired hypothalamic obesity has been extended by three months from December 20, 2025 to March 20, 2026.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

The following ~~Exhibit~~Exhibits 99.1 ~~relates~~and ~~to Item 2~~99.022 ~~and~~ shall be deemed to be furnished, and not filed:.

ExhibitNo.		Description

99.1		Press release dated November 4, 2025
Exhibit
104		Cover Page Interactive Data File (embedded within the inline XBRL document)
No.		Description
99.1		Press release dated November 7, 2025
99.2		Presentation dated November 7, 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, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	RHYTHM PHARMACEUTICALS, INC.
Date: November 4, 2025	By:	/s/ Hunter C. Smith
Date: November 7, 2025	By:	/s/ Hunter Smith
		Hunter C. Smith
		Hunter Smith
		Chief Financial Officer

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