PRNB Principia Biopharma Inc

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE TO

Tender Offer Statement under Section 14(d)(1) or 13(e)(1)

of the Securities Exchange Act of 1934

(Amendment No. 2)

Principia Biopharma Inc.

(Name of Subject Company (Issuer))

KORTEX ACQUISITION CORP.

AVENTIS INC.

SANOFI

(Names of Filing Persons — Offerors)

Common Stock, Par Value $0.0001 Per Share

(Title of Class of Securities)

74257L108

(Cusip Number of Class of Securities)

Karen Linehan

Executive Vice President Legal Affairs and General Counsel

Sanofi

54, Rue La Boétie, 75008

Paris, France

Telephone: 011 + 33 1 53 77 40 00

(Name, Address and Telephone Number of Person Authorized to Receive Notices and

Communications on Behalf of Filing Persons)

Copies to:

Michael J. Aiello, Esq.

Sachin Kohli, Esq.

Weil, Gotshal & Manges LLP

767 Fifth Avenue

New York, New York 10153

(212) 310-8000

CALCULATION OF FILING FEE

Check the appropriate boxes below to designate any transactions to which the statement relates:

Check the following box if the filing is a final amendment reporting the results of the tender offer:  ☐

If applicable, check the appropriate box(es) below to designate the appropriate rule provision(s) relied upon:

This Amendment No. 2 (this “Amendment”) amends and supplements the Tender Offer Statement on Schedule TO filed by (i) Kortex Acquisition Corp., a Delaware corporation (“Purchaser”) and a wholly owned subsidiary of Sanofi, a French société anonyme (“Parent”), (ii) Parent, and (iii) Aventis Inc., a Delaware corporation and a direct wholly owned subsidiary of Parent and direct parent of Purchaser (“Aventis”) on August 28, 2020 (together with any subsequent 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, $0.0001 per share (the “Shares”), of Principia Biopharma Inc., a Delaware corporation (the “Company”), at a purchase price of $100.00 per Share (the “Offer Price”) net to the seller in cash, without interest and subject to any withholding of taxes required by applicable legal requirements, on the terms and subject to the conditions set forth in the Offer to Purchase, as it may be amended or supplemented from time to time, and in the related Letter of Transmittal, as it may be amended or supplemented from time to time, copies of which are attached to 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.

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:

“The HSR Condition has been satisfied by the expiration of the waiting period under the HSR Act with respect to the Offer effective September 21, 2020 at 11:59 p.m., Eastern Time. The Offer continues to be subject to the remaining conditions set forth in this Offer to Purchase.”

“The HSR Condition has been satisfied by the expiration of the waiting period under the HSR Act with respect to the Offer effective September 21, 2020 at 11:59 p.m., Eastern Time. The Offer continues to be subject to the remaining conditions set forth in this Offer to Purchase.”

“The HSR Condition has been satisfied by the expiration of the waiting period under the HSR Act with respect to the Offer effective September 21, 2020 at 11:59 p.m., Eastern Time. The Offer continues to be subject to the remaining conditions set forth in this Offer to Purchase.”

“On September 21, 2020 at 11:59 p.m., Eastern Time, the waiting period under the HSR Act with respect to the Offer expired. The Offer continues to be subject to the remaining conditions set forth in this Offer to Purchase.”

“Nevertheless, and even though the requisite waiting period under the HSR Act has expired, neither Parent nor the Company can be certain that a challenge to the Offer or the Merger on antitrust grounds will not be made, or, if such challenge is made, what the result will be. If the FTC believes that the Offer may substantially lessen competition in any line of commerce in violation of the U.S. federal antitrust laws, the FTC has the authority to challenge the transaction by seeking a federal court order enjoining the transaction or, if Shares have already been acquired, requiring disposition of such Shares, or the divestiture of assets of Parent, the Company or any of their respective subsidiaries or affiliates. The Antitrust Division, U.S. state attorneys general and private persons may also bring legal action under the U.S. federal and state antitrust laws. See Section 15 —“Conditions of the Offer.””

Item 12. Exhibits.

Item 12 of the Schedule TO is hereby amended and supplemented by adding the following exhibit:

SIGNATURES

After due inquiry and to the best knowledge and belief of the undersigned, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Date: September 22, 2020