Entry into a Material Definitive Agreement. On October 30, 2026, Parabilis Medicines, Inc. (the “Company”) and LS 400/500 CDP, LLC (the “Landlord”) entered into a Third Amendment of Lease (the “Amendment”), which amends certain provisions of that certain Lease Agreement, by and between the Company and 400 Discovery Park, LLC, dated as of April 22, 2019, as amended (the “Lease”), regarding the Company’s corporate headquarters located at 30 Acorn Park Drive, Cambridge, Massachusetts (the “Exist…

Chief Medical Officer — Fawzi Benzaghou, M.D.: The Chief Medical Officer is departing via a mutually agreed transition with severance, representing a genuine loss of a senior executive but not a sudden or forced termination.

Director — Craig Tendler: The filing discloses the appointment of a new independent director to fill a newly created vacancy, which is a routine board composition change rather than an executive departure.

of this Current Report on Form 8-K, including Exhibit 99.1, is being furnished and 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, and shall not be incorporated by reference in any filing under the Securities Act of 1933, as amended (the “Securities Act”), or the Exchange Act, except as expressly set forth by specific reference in such filing.

Entry into a Material Definitive Agreement. On June 9, 2026, Parabilis Medicines, Inc. (the “Company”) entered into a Stock Purchase Agreement (the “Purchase Agreement”) with Regeneron Pharmaceuticals, Inc. (“Regeneron”), for the purchase of an aggregate of 4,166,666 shares (the “Shares”) of its voting common stock, par value $0.0001 (“Common Stock”), at a per share price equal to 90% of the initial public offering (“IPO”) price of $20.00 per share, through a private placement financing (the…

The Shares issued and sold in the Private Placement have not been registered under the Securities Act of 1933, as amended (the “Securities Act”), or applicable state securities laws, and were issued and sold pursuant to Section 4(a)(2) of the Securities Act. Regeneron has represented that it is an “institutional accredited investor” within the meaning of Rule 501 of Regulation D under the Securities Act, and is acquiring the Shares for investment purposes only and not with a view to any publi…