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): April 2, 2020

LANTHEUS HOLDINGS, INC.

(Exact name of registrant as specified in its charter)

331 Treble Cove Road

North Billerica, Massachusetts 01862

(Address of principal executive offices) (Zip code)

Registrant’s telephone number, including area code : (978) 671-8001

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 (see General Instruction A.2. below):

☒    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:

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. ☐

On April 2, 2020, Lantheus Holdings, Inc. (“Lantheus”) and Progenics Pharmaceuticals, Inc. (“Progenics”) announced that they have decided to reschedule their respective special meetings of stockholders to vote on the matters related to the proposed merger of Lantheus and Progenics from April 28, 2020, to June 16, 2020. The rescheduled special meetings will allow both companies the time necessary to respond to the COVID-19 pandemic and its effect on each company’s business and on the combined entity.

A copy of the press release is attached as Exhibit 99.1 and incorporated herein by reference.

(d) The following exhibits are included with this report:

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: April 2, 2020