This Amendment No. 3 to the Tender Offer Statement on Schedule TO (this “Amendment”) amends
and supplements the Tender Offer Statement on Schedule TO filed with the Securities and Exchange Commission (the “SEC”) on April 22, 2024 (as it may be further amended and supplemented from time to time, the “Schedule TO”)
and relates to the offer by Adams Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Vertex Pharmaceuticals Incorporated (“Vertex”), a Massachusetts corporation, to purchase all of the issued and outstanding shares
of common stock, par value $0.001 per share (the “Shares”), of Alpine Immune Sciences, Inc., a Delaware corporation, 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 described in the Offer to Purchase dated April 22, 2024 (together with any amendments or supplements thereto, the “Offer to Purchase”) and in the accompanying Letter of
Transmittal (together with the Offer to Purchase, as each may be amended or supplemented from time to time, collectively constitute the “Offer”), which are annexed to and filed with the Schedule TO as Exhibits (a)(1)(A) and
(a)(1)(B), respectively.
Except as otherwise set forth in this Amendment, the information set forth in the Schedule TO 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 respective meanings ascribed to them in the Schedule TO.
Items 1 through 9 and Item 11.
The Offer to
Purchase and Items 1 through 9 and Item 11 of the Schedule TO are hereby amended and supplemented as follows:
“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. The Depositary 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and not properly withdrawn pursuant to the Offer, representing approximately 87% of the Shares issued and outstanding as of immediately following the consummation of the Offer.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satisfied, on May 18, 2024, Purchaser irrevocably accepted for payment all the Shares validly tendered and not properly withdrawn pursuant to the Offer prior to the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 Nasdaq, and will be deregistered under the Exchange Act.”