This Amendment No. 2 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 (together with any amendments and supplements thereto, the Schedule TO) and relates
to the offer by Adams Merger Sub, Inc. (Merger Sub), 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. (Alpine), 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 (which 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.
The Offer will expire at one minute past 11:59 p.m., Eastern Time, on
May 17, 2024, unless the expiration of the Offer is extended to a subsequent date in accordance with the terms of the Merger Agreement (such date and time or such subsequent time on such subsequent date, the Expiration Time). In the
case of an extension of the Expiration Time, a public announcement of such extension will be made no later than 9:00 a.m., Eastern Time, on the business day after the previously scheduled Expiration Time. The terms and conditions relating to the
Offer, including the procedures regarding the extension of the Expiration Time, are described in the Offer to Purchase.
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.
Amendments to the Offer to Purchase:
Items 1 through 11.
The
information set forth in the Offer to Purchase under Section 16Certain Legal Matters; Regulatory Approvals and Items 1 through 11 of the Schedule TO, to the extent such Items incorporate by reference the information contained
in the Offer to Purchase, are hereby amended and supplemented by adding the following paragraph at the end of the subsection titled Antitrust Compliance which begins on page 47 of the Offer to Purchase:
On April 24, 2024, each of Vertex and Alpine filed its respective HSR Notification Forms with the FTC and the DOJ in connection
with the purchase of Shares pursuant to the Offer. The required waiting period under the HSR Act with respect to the Offer and the Merger expired at 11:59 p.m., Eastern Time, on May 9, 2024. Accordingly, the condition that the waiting period
under the HSR Act applicable to the purchase of Shares pursuant to the Offer and the consummation of the Merger has either expired or been terminated, described in Section 15Conditions of the Offer, has been satisfied.