This Amendment No. 3 (this “Amendment”) to Schedule
14D-9 amends and supplements the Solicitation/Recommendation Statement on Schedule 14D-9 previously filed by Alpine Immune Sciences, Inc., a Delaware corporation
(“Alpine”), with the Securities and Exchange Commission (the “SEC”) on April 22, 2024 (together with any amendments and supplements thereto, the “Schedule
14D-9”), relating to the cash tender offer (the “Offer”) by Adams Merger Sub, Inc. (“Purchaser”), a Delaware corporation and wholly owned subsidiary of Vertex
Pharmaceuticals Incorporated, a Massachusetts corporation (“Vertex”), to purchase all of the issued and outstanding shares of Alpine’s common stock, par value $0.001 per share (the “Shares”), at a purchase
price of $65.00 per Share, net to the seller in cash, without interest thereon, and subject to any applicable tax withholding, upon the terms and subject to the conditions set forth in the Offer to Purchase, dated as of April 22, 2024 (as may
be amended or supplemented from time to time, the “Offer to Purchase”) and the related Letter of Transmittal (as may be amended or supplemented from time to time, the “Letter of Transmittal”), and pursuant to the
Agreement and Plan of Merger, dated as of April 10, 2024, by and among Alpine, Vertex and Purchaser (as may be amended from time to time, the “Merger Agreement,” and the transactions contemplated therein, the
“Transactions”).
Except as otherwise set forth in this Amendment, the information set forth in the Schedule 14D-9 remains unchanged and is incorporated herein by reference to the extent relevant to the items in this Amendment. Capitalized terms used but not defined herein have the meanings ascribed to them in the Schedule
14D-9.
Item 8. Additional Information.
Item 8 of the Schedule 14D-9 is hereby amended and supplemented by adding the following section
after the last paragraph:
“Expiration of Offering Period; Completion of Merger
At one minute past 11:59 p.m., Eastern Time, on May 17, 2024 (the “Expiration Time”), the Offer expired and was not further extended. Broadridge
Corporate Issuer Solutions, LLC, the depositary for the Offer, advised Purchaser that, as of the Expiration Time, a total of 60,690,166 Shares were validly tendered and not properly withdrawn pursuant to the Offer, representing approximately 87% of
the Shares issued and outstanding as of immediately following the consummation of the Offer. The number of Shares tendered satisfied the Minimum Tender Condition. As the Minimum Tender Condition and each of the other conditions of the Offer were
satisfied, on May 18, 2024, Purchaser irrevocably accepted for payment all the Shares validly tendered and not properly withdrawn pursuant to the Offer prior to the Expiration Time, and will pay for such Shares as required by the Merger
Agreement.
Following the consummation of the Offer on May 20, 2024, Vertex completed its acquisition of Alpine, pursuant to the terms of the Merger
Agreement, through the merger of Purchaser with and into Alpine without a meeting of the Alpine stockholders in accordance with Section 251(h) of the DGCL, with Alpine continuing as the Surviving Corporation and a wholly owned subsidiary of
Vertex.
As a result of the Merger, the Shares will be delisted from and will cease to trade on The Nasdaq Stock Market, and will be deregistered under
the Exchange Act.”