This Amendment No. 1 (this “Amendment”) amends and supplements the Tender Offer
Statement on Schedule TO filed by (i) Rothko Merger Sub, Inc., a Delaware corporation (“Purchaser”) and an indirect wholly owned subsidiary of SANOFI, a French société anonyme (“Parent”),
(ii) Parent, and (iii) Aventis Inc., a Pennsylvania corporation and wholly owned subsidiary of Parent and direct parent of Purchaser (“Aventis”) on June 17, 2025 (together with any amendments or supplements thereto,
including this Amendment, the “Schedule TO”), relating to the offer by Purchaser to purchase all of the outstanding shares of common stock, par value, $0.001 per share (each a “Share” and collectively,
“Shares”), of Blueprint Medicines Corporation, a Delaware corporation (the “Company”), for $129.00 per Share in cash, without interest (the “Cash Offer Price”) and subject to any withholding of
taxes required by applicable legal requirements, plus one (1) non-transferable contractual contingent value right (each, a “CVR”) per Share, representing the right to receive
contingent payments of up to an aggregate amount of $6.00 per Share in cash, without interest, upon the achievement of one or both of the milestones on or prior to the expiration of the applicable milestone period set forth in the CVR Agreement to
be entered into with a Rights Agent mutually agreeable to Aventis and the Company (the CVR, together with the Cash Offer Price, or any other amount paid pursuant to the Offer to the extent permitted under the Merger Agreement, the “Offer
Consideration”), on the terms and subject to the conditions set forth in the Offer to Purchase, dated June 17, 2025 (together with any amendments or supplements thereto, the “Offer to Purchase”) and in the accompanying
Letter of Transmittal, which are annexed to and filed with the Schedule TO as Exhibits (a)(1)(A) and (a)(1)(B), respectively.
All information set forth
in the Offer to Purchase, including Schedule I thereto, is incorporated by reference herein in response to Items 1 through 9 and Item 11 of this Schedule TO and is supplemented by the information specifically provided in this Amendment, except as
otherwise set forth below. This Amendment should be read together with the Schedule TO. Capitalized terms used and not otherwise defined in this Amendment have the meanings given to such terms in the Offer to Purchase.
Items 1 through 9 and Item 11.
The Offer to
Purchase and Items 1 through 9 and Item 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 as follows:
| (1) |
The second paragraph of the subsection entitled “Antitrust Compliance” in Section 16 –
“Certain Legal Matters; Regulatory Approvals” is amended and supplemented by deleting the second paragraph and adding the following paragraph: |
“Under the HSR Act, the purchase of Shares may not be completed until the expiration of
a 30-calendar day waiting period following the filing of certain required information and documentary material concerning the Offer with the FTC and the Antitrust Division, unless the waiting period
is earlier terminated by the FTC and the Antitrust Division. The waiting period under the HSR Act expired, effective July 9, 2025 at 11:59 p.m., Eastern Time. Accordingly, the condition to the Offer requiring that the waiting period (or any
extension thereof) applicable to the Offer and the Merger under the HSR Act shall have expired or been terminated has been satisfied.”
| (2) |
The subsection entitled “Austria Merger Control Compliance” in Section 16 – “Certain
Legal Matters; Regulatory Approvals” is amended and supplemented by deleting the last sentence of the paragraph and adding the following sentence at the end of the paragraph: |
“The expiry of the statutory (Phase I) waiting period occurred on July 8, 2025 (24:00 Central European Time).”
