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. 3)

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. 3 (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, except as otherwise set forth below. This Amendment should be read together with 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, to the extent such Items incorporate by reference the information contained in the Offer to Purchase, are hereby amended and supplemented as follows:

“The Offer and withdrawal rights expired as scheduled at one minute following 11:59 p.m., Eastern Time, on September 25, 2020 (such date and time, the “Expiration Time”), and the Offer was not extended. Purchaser was advised by the Depositary that, as of the Expiration Time, a total of 26,995,086 Shares (not including 3,077,763 Shares tendered by notice of guaranteed delivery for which Shares have not yet been delivered in satisfaction of such guarantee) had been validly tendered into and not validly withdrawn pursuant to the Offer, representing approximately 81.1% of the aggregate number of Shares then outstanding. Accordingly, the number of Shares validly tendered and not validly withdrawn pursuant to the Offer satisfied the Minimum Condition.

Purchaser has irrevocably accepted for payment, and has stated it will promptly pay for, all Shares validly tendered and not validly withdrawn pursuant to the Offer.

As a result of its acceptance of the Shares tendered pursuant to the Offer and in accordance with Section 251(h) of the DGCL, Purchaser owns a number of Shares that is greater than the percentage of Shares that would be required to adopt the Merger Agreement by a vote of the stockholders of the Company. Pursuant to Section 251(h) of the DGCL, subject to the satisfaction of the remaining conditions set forth in the Merger Agreement, Parent and Purchaser intend to complete the acquisition of the Company through the Merger, as promptly as practicable and without a meeting of stockholders of the Company. At the Effective Time and as a result of the Merger, each Share issued and outstanding immediately prior to the Effective Time will be converted into the right to receive an amount in cash equal to the Offer Price, without interest and subject to any withholding of taxes required by applicable legal requirements, other than Shares (i) held by the Company (or in the Company’s treasury), Parent, Purchaser, any other direct or indirect wholly owned subsidiary of Parent, or by stockholders of the Company who have properly exercised and perfected their statutory rights of appraisal under Delaware law, or (ii) irrevocably accepted for purchase in the Offer.

Following the Merger, the Shares will no longer be listed on the NASDAQ Global Select Market and will be deregistered under the Exchange Act.”

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 28, 2020