UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): ~~December 5~~January 23, ~~2019~~2020

Synthorx, Inc.

(Exact name of registrant as specified in its charter)

Delaware	001-38756	46-4709185
(State or other jurisdictionof incorporation)	(CommissionFile Number)	(I.R.S. EmployerIdentification No.)
(State or other jurisdiction of incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)

11099 N. Torrey Pines Road, Suite 190

La Jolla, California

92037

(Address of principal executive offices)

(Zip Code)

Registrant’s telephone number, including area code: (858) 750-4789

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading

Symbol(s)

Name of each exchange

on which registered

Common Stock, par value $0.001 per share

THOR

The Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☒

Item 12.01 ~~Entry~~Completion ~~into~~of aAcquisition ~~Material~~or ~~Definitive~~Disposition ~~Agreement~~of Assets.

As previously disclosed, on December 7, 2019, Synthorx, Inc., a Delaware corporation (“Synthorx” or the “Company”), entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Sanofi, a French société anonyme (“Parent”), and Thunder Acquisition Corp., a Delaware corporation and an indirect wholly owned subsidiary of Parent (“Purchaser”). Aventis Inc., a Delaware corporation and a direct wholly owned subsidiary of Parent (“Aventis”) is the direct parent of Purchaser.

OnPursuant to the Merger Agreement, on December 723, 2019, ~~Synthorx,~~ ~~Inc.,~~Purchaser commenced a ~~Delaware~~tender ~~corporation~~offer ~~(the~~to ~~“Company”~~acquire orall ~~“Synthorx”),~~of ~~entered~~the ~~into~~outstanding anshares ~~Agreement~~of ~~and~~common ~~Plan~~stock of the ~~Merger~~Company, $0.001 par value per share (the “~~Merger Agreement~~Shares”) ~~with Sanofi~~, at a ~~French société~~purchase ~~anonyme~~price of $68.00 per Share in cash (the “~~Parent~~Offer Price”), without interest thereon and ~~Thunder~~net ~~Acquisition~~of ~~Corp.~~any applicable withholding taxes, aupon ~~Delaware~~the ~~corporation~~terms and asubject ~~wholly~~to ~~owned~~the conditions ~~subsidiary~~set offorth ~~Parent~~in the Offer to Purchase, dated December 23, 2019 (as amended or supplemented from time to time, the “~~Purchaser~~Offer to Purchase”)., ~~The~~and ~~board~~in ofthe ~~directors~~related Letter of Transmittal (which, together with the ~~Company~~Offer ~~has~~to Purchase, as ~~unanimously~~each ~~approved~~may ~~the~~be ~~Merger~~amended ~~Agreement~~or supplemented from time to time, constitute the “Offer”).

~~Pursuant~~On toJanuary 23, ~~the~~2020, ~~Merger~~Parent ~~Agreement,~~announced ~~upon~~that the ~~terms~~offering period ~~and~~of ~~subject~~the toOffer ~~the~~had ~~conditions~~expired ~~thereof,~~at ~~Purchaser~~one ~~will commence~~minute apast ~~cash~~11:59 ~~tender~~p.m., ~~offer~~Eastern Time, on January 22, 2020 (the “~~Offer~~Expiration Time”) noand ~~later~~that ~~than~~as ~~December 23~~of such time, ~~2019~~based on the information provided by the depositary for the Offer, 27,443,994 Shares (not including 1,135,448 Shares tendered by notice of guaranteed delivery for which Shares have not yet been delivered in satisfaction of such guarantee) were validly tendered and not validly withdrawn pursuant to ~~acquire~~the ~~all~~Offer prior to the Expiration Time, representing approximately 83.7% of the outstanding ~~shares~~Shares as of ~~common~~such ~~stock~~time, which Shares were sufficient to have met the minimum condition of the ~~Company,~~Offer ~~$0.001~~and ~~par~~to ~~value~~enable ~~per~~the ~~share~~Merger (~~the~~as ~~“Shares”~~defined below), atto occur under Delaware law without a ~~purchase~~ ~~price~~vote of the ~~$68~~Company’s stockholders.00 ~~per~~All ~~Share~~conditions into ~~cash (~~the “Offer ~~Price”)~~having been satisfied, ~~without~~on ~~interest~~January 23, 2020, Purchaser accepted for payment all Shares validly tendered and ~~subject~~not validly withdrawn prior to ~~any~~the ~~required~~Expiration ~~withholding~~Time, and will promptly pay for such Shares in accordance with the terms of ~~taxes~~the Offer.

~~The~~Following ~~obligation~~the completion of ~~Purchaser~~the toOffer, ~~purchase~~on ~~Shares~~January 23, ~~tendered~~2020, inpursuant to the ~~Offer~~terms isof ~~subject~~the Merger toAgreement ~~the~~and ~~conditions~~in ~~set~~accordance ~~forth~~with inSection 251(h) of the ~~Merger~~General ~~Agreement,~~Corporation ~~including~~Law ~~that~~of the ~~number~~ State of ~~Shares~~Delaware ~~validly~~(the ~~tendered~~“DGCL”), inPurchaser ~~accordance~~merged with and into the ~~terms~~Company of(the “Merger”), with the ~~Offer~~Company continuing as the surviving corporation (the “Surviving Corporation”) and ~~not~~an ~~validly~~indirect ~~withdrawn,~~wholly ~~when~~owned ~~considered~~subsidiary ~~together~~of ~~with~~Parent. ~~all~~In ~~other~~the Merger, Shares ~~(if~~that ~~any)~~were ~~otherwise~~not ~~beneficially~~purchased pursuant to the Offer (other than (i) Shares owned by Purchaser, Parent or any ofother direct ~~its~~or indirect wholly owned ~~subsidiaries~~subsidiary of Parent immediately prior to the Effective Time (~~including Purchaser~~as defined below), ~~would~~(ii) ~~represent~~Shares ~~one~~owned ~~more~~by ~~than~~the ~~50%~~Company of(or held in the ~~total~~Company’s ~~number~~treasury) or (iii) Shares held by any stockholder that is entitled to demand appraisal and who has properly exercised and perfected a demand for appraisal of such Shares ~~outstanding~~pursuant atto, ~~the~~and ~~time~~who has complied in all respects with, Section 262 of the ~~expiration~~DGCL and who, as of the ~~Offer~~Effective ~~(the~~Time, ~~“Minimum~~has ~~Condition”).~~neither ~~Parent~~effectively withdrawn ~~and~~nor ~~Purchaser~~lost such stockholder’s ~~obligations~~rights to ~~consummate~~such appraisal and payment under the ~~Offer~~DGCL ~~are not~~with ~~subject~~respect to asuch ~~condition~~Shares) ~~that~~were ~~any~~converted ~~financing~~into bethe ~~received~~right byto ~~Parent~~receive oran ~~Purchaser~~amount ~~for~~in ~~the~~cash ~~consummation~~equal ofto the ~~transactions~~Offer ~~contemplated~~Price by (the “Merger ~~Agreement~~Consideration”), without any interest thereon and net of any applicable withholding taxes.

~~Following~~Pursuant ~~the completion of the Offer and subject~~ to the ~~satisfaction or waiver of certain conditions set forth in the~~ Merger Agreement, ~~Purchaser~~each ~~will~~of ~~merge with and into~~ the Company,’s ~~with~~stock ~~the~~options ~~Company surviving as a wholly owned subsidiary of Parent~~ (the “~~Merger~~Company Options”). ~~Purchaser~~that ~~will~~was ~~effect~~outstanding ~~the~~as ~~Merger after consummation~~ of ~~the~~immediately ~~Offer~~prior ~~pursuant~~ to ~~Section 251(h) of~~ the ~~Delaware General Corporation Law. At the~~ effective time of the Merger (the “Effective Time”), ~~the~~accelerated ~~Shares~~and ~~then~~became ~~outstanding~~fully ~~(other~~vested ~~than~~and ~~Shares~~exercisable ~~(a) held~~effective byimmediately ~~Parent,~~prior ~~Purchaser~~to, ~~any~~and ~~other~~contingent ~~direct or indirect wholly owned subsidiary of Parent~~upon, the ~~Company~~Effective ~~(or~~Time inand ~~the~~has ~~Company’s~~been ~~treasury)~~cancelled orand byconverted ~~stockholders~~into of the ~~Company~~right ~~who~~to ~~have~~receive ~~exercised~~cash ~~and~~in ~~perfected~~an ~~their~~amount, ~~statutory~~net ~~rights~~ of ~~appraisal~~any ~~under~~applicable ~~Delaware~~withholding ~~law~~taxes, orequal to the product of (bi) ~~irrevocably~~the ~~accepted~~total ~~for~~number ~~purchase~~of inShares ~~the~~subject ~~Offer)~~to ~~will~~such ~~each~~vested Company Option beimmediately ~~converted~~prior ~~into~~to the ~~right~~Effective toTime ~~receive~~(taking aninto ~~amount~~account inany ~~cash~~acceleration ~~equal~~of tovesting), multiplied by (ii) the ~~Offer~~excess ~~Price~~of (x) the “Merger Consideration~~”),~~ ~~without~~over ~~interest~~(y) the ~~and~~exercise ~~subject~~price topayable ~~any~~per ~~required~~Share ~~withholding~~underlying ofsuch ~~taxes.~~Company Option.

~~Each~~Pursuant to the Merger Agreement, each of the Company’s restricted stock ~~options~~units (the “~~Company Options~~RSUs”) that iswas outstanding as of immediately prior to the Effective Time ~~shall~~, ~~accelerate~~whether ~~and become fully~~ vested ~~and~~or ~~exercisable effective immediately prior to~~unvested, ~~and~~has ~~contingent~~been ~~upon, the Effective Time. As of the Effective Time, each Company Option that is then outstanding and unexercised shall be~~ cancelled and converted into the right to receive cash in an amount, net of any applicable withholding taxes, equal to the product of (i) the total number of Shares ~~subject~~issuable toin settlement ~~the vested portion~~ of such ~~Company~~RSU ~~Option~~ immediately prior to the Effective Time ~~(taking~~without ~~into~~regard ~~account~~to ~~any acceleration of~~ vesting), multiplied by (ii) the ~~excess,~~Merger ifConsideration ~~any,~~for ofeach ~~(x) the~~Share ~~Merger~~issuable ~~Consideration~~in ~~over~~settlement ~~(y) the~~of ~~exercise~~such ~~price~~RSU ~~payable~~immediately ~~per~~prior ~~Share~~to ~~under~~the ~~such~~Effective ~~Company Option~~Time.

The ~~Merger~~total ~~Agreement~~consideration ~~includes~~paid ~~representations,~~for ~~warranties and covenants of~~ the ~~parties~~Shares ~~customary~~in ~~for a transaction of this nature. From~~ the ~~date~~Offer ofand the Merger ~~Agreement~~ ~~until~~was ~~the~~approximately ~~earlier~~$2.48 billion. ofThese ~~the~~amounts ~~Effective~~exclude ~~Time~~fees and ~~the~~expenses ~~termination~~related to of the ~~Merger~~Offer ~~Agreement,~~and the ~~Company~~Merger. ~~has~~Parent ~~agreed~~provided toPurchaser ~~operate~~with ~~its~~sufficient ~~business~~funds ~~in the ordinary course and has agreed~~ to ~~certain~~purchase ~~other~~all ~~operating~~Shares ~~covenants,~~accepted asfor ~~set~~payment ~~forth more fully~~ in the ~~Merger~~ ~~Agreement.~~offering ~~The~~period ~~Company~~of ~~has~~the ~~also~~Offer ~~agreed~~and ~~not~~all toShares ~~solicit~~purchased orin ~~initiate~~the ~~discussions with any third party regarding acquisition proposals~~Merger.

The ~~Merger Agreement~~foregoing ~~includes~~description ~~a remedy~~ of ~~specific performance for~~ the ~~Company, Parent and Purchaser. The~~ Merger Agreement ~~also includes customary termination provisions for both the Company~~ and ~~Parent and provides that, in connection with~~ the ~~termination~~related ~~of the~~transactions ~~Merger~~does ~~Agreement~~not ~~under~~purport ~~specified circumstances, including termination by the Company~~ to ~~accept and enter into a definitive agreement with respect to an unsolicited superior offer, the Company will~~ be ~~required~~complete toand ~~pay~~is aqualified ~~termination fee of an amount~~ in ~~cash~~its ~~equal~~entirety by reference to ~~$94,000,000 (~~the ~~“Termination~~full ~~Fee”).~~text ~~Any such termination~~ of the Merger Agreement, bya ~~the~~copy ~~Company~~of which is ~~subject~~filed toas ~~certain~~Exhibit ~~conditions,~~2.1 ~~including~~to the ~~Company’s~~Current ~~compliance~~Report ~~with~~on ~~certain~~Form ~~procedures~~8-K ~~set forth~~filed ~~in the Merger Agreement and a determination~~ by the ~~board of directors of the~~ Company ~~that the failure to take such action would be inconsistent~~ with the ~~board~~U.S. ofSecurities ~~directors’~~and ~~fiduciary~~Exchange ~~duties~~Commission to (the ~~Company’s stockholders under~~“SEC”) ~~applicable~~on ~~law~~December 9, 2019, and ~~the~~is ~~payment~~incorporated ofherein ~~the Termination Fee~~ by ~~the Company~~reference.

~~The~~Item ~~foregoing description of the Merger Agreement is not complete and is qualified in its entirety by reference to the Merger Agreement, which is attached as Exhibit 2~~3.~~1 to this report and incorporated herein by reference~~01. ~~The~~Notice ~~Merger Agreement and the foregoing description~~ of ~~such~~Delisting ~~agreement~~or ~~have~~Failure ~~been included~~ to ~~provide~~Satisfy investors and stockholders with information regarding the terms of such agreements. The assertions embodied in the representations and warranties contained in the Merger Agreement are qualified by information in confidential disclosure schedules delivered by the Company to Parent and Purchaser in connection with the signing of the Merger Agreement. Moreover, certain representations and warranties in the Merger Agreement were made as of a ~~specified~~Continued ~~date,~~Listing ~~may~~Rule ~~be subject to a contractual standard of materiality different from what might be viewed as material to stockholders,~~ or ~~may~~Standard; ~~have~~Transfer ~~been used for the purpose~~ of ~~allocating risk between the parties to the Merger Agreement~~Listing. Accordingly, the representations and warranties in the Merger Agreement should not be relied on by any persons as characterizations of the actual state of facts and circumstances of the Company at the time they were made and investors should consider the information in the Merger Agreement in conjunction with the entirety of the factual disclosure about the Company in the Company’s public reports filed with the SEC. Information concerning the subject matter of the representations and warranties may change after the date of the Merger Agreement, which subsequent information may or may not be fully reflected in the Company’s public disclosures.

~~Item~~On ~~5.02~~January 23, ~~Departure~~2020, the Company notified the Nasdaq Global Select Market (“NASDAQ”) of ~~Directors~~the consummation of the Merger, and requested that NASDAQ (i) suspend trading of the Shares before the opening of trading on January 23, 2020 and (ii) file with the SEC a Notification of Removal from Listing and/or ~~Certain~~Registration ~~Officers;~~under ~~Election~~Section 12(b) of ~~Directors;~~the ~~Appointment~~Securities Exchange Act of ~~Certain~~1934, ~~Officers;~~as ~~Compensatory~~amended ~~Arrangements~~(the “Exchange Act”), on Form 25 to effect the delisting of ~~Certain~~shares ~~Officers~~of the Company’s common stock from NASDAQ and to deregister the Shares under Section 12(b) of the Exchange Act. In addition, the Company intends to file with the SEC a certification on Form 15 under the Exchange Act requesting the Company’s reporting obligations under Sections 13 and 15(d) of the Exchange Act be suspended.

~~Executive~~Item ~~Compensation~~3.03. ~~Arrangements~~Material Modification to Rights of Security Holders.

OnThe ~~December 5,~~disclosure ~~2019,~~contained in ~~connection~~Items ~~with~~2.01 ~~the approval of the Merger Agreement, the board of directors of the Company approved~~ and ~~authorized the Company to enter into agreements with each of Dr~~3. ~~Laura~~01 ~~Shawver,~~above ~~the Company’s President~~ and ~~Chief~~in ~~Executive~~Items ~~Officer, Dr~~5. ~~Joseph~~01 ~~Leveque,~~and ~~the Company’s Chief Medical Officer, Dr~~5. ~~Marcos~~03 ~~Milla,~~below ~~the Company’s Chief Scientific Officer, and certain other individuals, which provide that if such individual~~ is ~~subjected~~incorporated toherein ~~the~~by excise tax under Section 4999 of the Internal Revenue Code, the Company will reimburse such individual with respect to the payment for the excise taxes (provided that the Company’s obligation under these agreements cannot exceed $35 million in the aggregate and that such individuals will reasonably cooperate with Parent and the Company to mitigate such excise taxes)reference.

Item 85.01. ~~Other~~Changes ~~Events~~in Control of Registrant.

OnThe disclosure ~~December 8,~~contained ~~2019,~~in ~~the~~Item ~~Company~~2.01 above and ~~Parent~~in ~~issued~~Item ~~a joint press release announcing the execution of the Merger Agreement as described above~~5.02 Abelow ~~copy of the press release~~ is ~~attached as Exhibit 99.1 and~~ incorporated herein by reference.

OnAs ~~December 8,~~a ~~2019,~~result of the consummation of the Offer and the Merger pursuant to Section 251(h) of the ~~Company~~DGCL, ~~sent~~on January 23, 2020, a ~~letter~~change toin ~~its employees~~control ~~announcing~~of the ~~proposed~~Company ~~transaction~~occurred. AAt ~~copy~~the ofEffective Time, the ~~letter~~Company isbecame ~~attached~~a asdirect ~~Exhibit~~wholly ~~99.2~~owned subsidiary of Aventis and ~~incorporated~~an ~~herein~~indirect bywholly ~~reference~~owned subsidiary of Parent.

~~Forward-Looking Statements~~Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

~~This~~Pursuant ~~Current~~to ~~Report~~the onMerger ~~Form~~Agreement, ~~8-K~~effective ~~contains~~immediately ~~forward-looking~~after ~~statements.~~the ~~Forward-looking~~Effective ~~statements~~Time, ~~are~~each ~~statements~~of ~~that~~(i) ~~are~~Vickie ~~not~~Capps, ~~historical~~Jay ~~facts and may include projections and estimates and their underlying assumptions~~Lichter, ~~statements regarding plans~~Ph.D., ~~objectives,~~Peter ~~intentions and expectations with respect to future financial results~~Kolchinsky, ~~events~~Ph.D., ~~operations,~~Andrew ~~services~~Powell, ~~product development and potential, and statements regarding future performance~~J. ~~Forward-looking statements are generally identified by the words “expects”~~D., ~~“anticipates”,~~Pratik ~~“believes”~~Shah, ~~“intends”, “estimates”, “plans”, “will be” and similar expressions~~Ph.D. ~~Although~~Laura ~~Synthorx’s management believes that the expectations reflected in such forward-looking statements are reasonable~~Shawver, ~~investors~~Ph.D. ~~are cautioned that forward-looking information~~ and ~~statements~~Peter ~~are~~Thompson, ~~subject~~M.D. toceased ~~various~~serving ~~risks~~as ~~and~~a ~~uncertainties,~~member ~~many~~ of ~~which are difficult to predict and generally beyond~~ the ~~control~~board of ~~Synthorx,~~directors ~~that~~of ~~could~~the ~~cause~~Company ~~actual results~~ and ~~developments~~each tocommittee ~~differ~~thereof ~~materially~~and ~~from~~(ii) ~~those~~Laura ~~expressed in~~Shawver, or ~~implied~~Ph.D., orTighe ~~projected by~~Reardon, ~~the~~Joseph ~~forward-looking~~Leveque ~~information and statements~~M.D. ~~These risks~~ and ~~uncertainties~~Marcos ~~include among other things~~Milla, ~~risks~~Ph.D. ~~relating~~ceased toserving ~~the~~as ~~ability~~an toofficer ~~complete and the timing~~ of ~~completion of~~ the transactions contemplated by the Merger Agreement including the parties’ ability to satisfy the conditions to the consummation of the Offer and the other conditions set forth in the Merger Agreement and the possibility of any termination of the Merger AgreementCompany. ~~The forward-looking statements contained in~~

~~this~~Further, ~~Current~~pursuant ~~Report on Form 8-K are based on current expectations and assumptions that are subject~~ to ~~risks and uncertainties which may cause actual results to differ materially from~~ the ~~forward-looking~~ ~~statements. Actual results may differ materially from current expectations because of risks associated with uncertainties as to the timing of the Offer or the~~ Merger; ~~the risk that competing offers or acquisition proposals will be~~Agreement ~~made;~~and ~~the~~effective ~~possibility~~immediately ~~that~~after ~~various conditions to~~ the ~~consummation~~Effective ~~of the Offer or the Merger may not be satisfied or waived~~Time, ~~including~~John ~~that~~Reed aand ~~governmental~~Marie ~~entity may prohibit~~Debans, ~~delay or refuse to grant approval for~~ the ~~consummation~~directors of, ~~the~~and ~~Offer~~President ~~or the~~and ~~Merger;~~Treasurer ~~the~~respectively ~~effects~~ of, ~~disruption~~Purchaser ~~from~~immediately ~~the~~prior ~~transactions~~to ofthe ~~Synthorx’s~~Effective ~~business~~Time ~~and~~became the ~~fact~~directors ~~that the announcement~~ and ~~pendency~~officers of the ~~transactions may make it more difficult to establish or maintain relationships with employees or vendors.~~Surviving ~~While the list of factors presented here is representative~~Corporation, noholding ~~list~~the ~~should~~same bepositions. ~~considered~~Information aregarding ~~statement of all potential risks, uncertainties or assumptions that could have a material adverse effect on~~ the ~~companies’~~new ~~consolidated~~directors ~~financial condition~~and orofficers ~~results~~ of ~~operations.~~the ~~The~~Company ~~foregoing~~has ~~factors~~been ~~should~~previously bedisclosed ~~read~~ in ~~conjunction with~~ the ~~risks~~Tender ~~and~~Offer ~~cautionary~~Statement ~~statements~~on ~~discussed~~Schedule orTO, ~~identified~~filed inby inPurchaser, ~~Synthorx’s~~Aventis ~~public~~and ~~filings~~Parent with the ~~United States Securities and Exchange Commission (“~~SEC”) ~~from time to time, including Synthorx’s most recent Annual Report~~ on ~~Form 10-K for the year ended~~ December 3123, ~~2018,~~2019 ~~Quarterly~~(together ~~Reports~~with onthe ~~Form~~exhibits ~~10-Q~~ and ~~Current~~annexes ~~Reports~~thereto onand ~~Form 8-K. Synthorx’s~~as ~~stockholders~~amended ~~and~~or ~~investors~~supplemented ~~are~~from ~~cautioned~~time ~~not~~ to ~~unduly~~time), ~~rely on these forward-looking statements. The forward-looking statements speak only as of the date hereof~~ and, ~~other~~is ~~than~~incorporated asherein ~~required~~ by ~~applicable law, Synthorx does not undertake any obligation to update or revise any forward-looking information or statements~~reference.

~~Additional~~Item ~~Information~~5.03. Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year.

~~The~~Pursuant ~~Offer~~to ~~for~~ the ~~outstanding~~Merger ~~shares~~Agreement, ofeffective ~~Synthorx~~as ~~common stock referenced in this Current Report on Form 8-K has not yet commenced. This communication is for informational purposes only and is neither an offer to purchase nor a solicitation~~ of anthe ~~offer~~Effective ~~to sell securities~~Time, ~~nor~~each isof ~~it a substitute for~~ the ~~tender~~certificate ~~offer~~of ~~materials~~incorporation ~~that~~and ~~will~~the bebylaws ~~filed~~of ~~with~~ the ~~SEC~~Company ~~upon~~was ~~the~~amended ~~commencement~~and restated ofin ~~the~~its ~~Offer~~entirety. AtCopies ~~the~~of ~~time~~ the ~~Offer~~certificate isof ~~commenced,~~incorporation ~~Sanofi~~ and ~~Purchaser~~bylaws ~~will~~are ~~file~~filed aas ~~Tender~~Exhibits ~~Offer~~3.1 ~~Statement~~and on3.2, ~~Schedule TO with the SEC~~respectively, ~~and~~to ~~Synthorx~~this ~~will~~Current ~~file~~Report ~~a Solicitation/Recommendation Statement~~ on ~~Schedule~~Form ~~14D~~8-9K ~~with~~and ~~respect~~are toincorporated ~~the~~herein ~~Offer.~~by reference.

~~THE~~Item ~~TENDER OFFER MATERIALS (INCLUDING AN OFFER TO PURCHASE, A RELATED LETTER OF TRANSMITTAL AND CERTAIN OTHER TENDER OFFER DOCUMENTS) AND THE SOLICITATION/RECOMMENDATION STATEMENT ON SCHEDULE 14D-~~9 ~~WILL CONTAIN IMPORTANT INFORMATION~~.01. ~~SYNTHORX~~Financial ~~STOCKHOLDERS~~Statements ~~ARE~~and URGED TO READ THESE DOCUMENTS CAREFULLY WHEN THEY BECOME AVAILABLE (AS EACH MAY BE AMENDED OR SUPPLEMENTED FROM TIME TO TIME) BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION THAT HOLDERS OF SYNTHORX SECURITIES SHOULD CONSIDER BEFORE MAKING ANY DECISION REGARDING TENDERING THEIR SECURITIES. Exhibits

~~The~~(d) Offer to Purchase, the related Letter of Transmittal and certain other offer documents, as well as the Solicitation/Recommendation Statement, will be made available to all stockholders of Synthorx at no expense to themExhibits. The Tender Offer Statement and the Solicitation/Recommendation Statement will be available free of charge at the SEC’s web site, http://www.sec.gov, or under the “Investors & Media” section of Synthorx’s website, www.synthorx.com. Free copies of these materials and certain other offering documents will be sent to Synthorx’s stockholders by the information agent for the Offer.

In addition to the Solicitation/Recommendation Statement, Synthorx files annual, quarterly and current reports, proxy statements and other information with the SEC. You may read and copy any reports, statements or other information filed by Synthorx at the SEC public reference room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the public reference room. Synthorx’s filings with the SEC are also available to the public from commercial document-retrieval services and the SEC’s website at http://www.sec.gov.


Number		Description

2.1		Agreement and Plan of Merger, dated as of December 7, 2019, by and among the Company, Parent and Purchaser (incorporated by reference to the Company’s Current Report on Form 8-K filed with the SEC on December 9, 2019).

3.1		Amended and Restated Certificate of Incorporation of the Company.

3.2		Second Amended and Restated Bylaws of the Company.

~~Item~~SIGNATURE ~~9.01. Financial Statements and Exhibits~~

~~(d)~~Pursuant ~~Exhibits~~to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Number	Description
		SYNTHORX, INC.
2.1*	Agreement and Plan of Merger, dated as of December 7, 2019, by and among Synthorx, Inc., Sanofi and Thunder Acquisition Corp.
Dated: January 23, 2020
99.1	Joint Press Release of Sanofi and Synthorx, Inc., dated December 8, 2019.
		By:	/s/ John Reed
99.2	Letter to Synthorx, Inc. employees, first made available on December 8, 2019.
			John Reed
			President

* Schedules omitted pursuant to Item 601(b)(2) of Regulation S-K. The Company agrees to furnish supplementally a copy of any omitted schedule to the SEC upon request.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

SYNTHORX, INC.

Dated: December 9, 2019

/s/ Laura Shawver

Laura Shawver, Ph.D.

President and Chief Executive Officer

Filing Compare · Synthorx, Inc.