UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

~~WASHINGTON~~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~~report (Date of ~~Earliest~~earliest ~~Event~~event ~~Reported~~reported): ~~October~~November 27, 2017

DIMENSION THERAPEUTICS, INC.

(Exact ~~name~~Name of ~~registrant~~Registrant as ~~specified~~Specified in its ~~charter~~Charter)

Delaware	001-37601	46-3942159
(State or other jurisdiction of incorporation)	(Commission File Number)	(IRS Employer Identification No.)
(State or Other Jurisdiction of Incorporation)	(Commission File Number)	(IRS Employer Identification No.)
840 Memorial Drive Cambridge, MA		02139
(Address of Principal Executive Offices)		(Zip Code)

840 Memorial Drive Cambridge, MA		02139
(Address of principal executive offices)		(Zip Code)

(617) 401-0011

(Registrant’s telephone number, including area code~~: (617~~) ~~401-0011~~

Not Applicable

(Former name or former address, if changed since last report.)

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:

☐	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))

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~~As 1previously disclosed in the Current Report on Form 8-K filed with the Securities and Exchange Commission (“SEC”) by Dimension Therapeutics, Inc.~~01.~~ ~~Entry~~(the “Company”) on October 2, 2017, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”), dated October 2, 2017, by and among the Company, Ultragenyx Pharmaceutical Inc. (“Ultragenyx”) and Mystic River Merger Sub Inc., a ~~Material~~wholly-owned ~~Definitive~~subsidiary of Ultragenyx (“Purchaser”). Pursuant to the Merger Agreement, Purchaser commenced a tender offer to purchase all of the issued and outstanding shares of the Company’s common stock, par value $0.0001 per share (the “Shares”), for a purchase price of $6.00 per Share, (the “Offer Price”), net to the holder in cash, without interest, and upon the terms and subject to the conditions set forth in the Offer to Purchase dated October 10, 2017 (the “Offer to Purchase”) and in the related Letter of Transmittal (which, together with the Offer to Purchase, as each may be amended or supplemented from time to time, constitute the “Offer”).

~~Merger~~Item ~~Agreement~~2.01 Completion of Acquisition or Disposition of Assets.

OnThe ~~October 2,~~Offer ~~2017,~~and withdrawal rights ~~Dimension~~expired ~~Therapeutics~~as scheduled at 12:00 midnight, ~~Inc.~~New York City time, aat ~~Delaware~~the ~~corporation~~end of the day on November 6, 2017 (~~“Dimension”~~such ordate and time, the “~~Company~~Expiration Time”). American Stock Transfer & Trust Company, ~~Ultragenyx~~LLC, ~~Pharmaceutical~~the ~~Inc.~~depositary, aadvised that, ~~Delaware~~as ~~corporation~~of ~~(“Ultragenyx”)~~the Expiration Time, 21,947,871 Shares had been validly tendered and ~~Mystic~~not ~~River~~properly ~~Merger~~withdrawn ~~Sub~~pursuant ~~Inc.~~to the Offer, ~~a Delaware~~representing ~~corporation~~approximately 86.5% of the aggregate number of then issued and outstanding Shares. Because the Shares validly tendered and not validly withdrawn constituted a ~~direct~~majority of the outstanding Shares entitled to vote, ~~wholly-owned~~the ~~subsidiary~~minimum tender condition for the Offer was satisfied. All other conditions to the Offer were also satisfied as of ~~Ultragenyx~~the ~~(“Purchaser”)~~expiration of the Offer. As a result, ~~entered~~Purchaser ~~into~~has anaccepted ~~Agreement~~for payment all Shares that were validly tendered and ~~Plan~~not ofproperly ~~Merger~~withdrawn ~~(the~~pursuant ~~“Merger~~to ~~Agreement”)~~the Offer.

~~Pursuant~~On toNovember 7, ~~the Merger Agreement~~2017, ~~and~~pursuant ~~upon~~to the terms ~~and~~of ~~subject to~~ the ~~conditions~~Merger ~~thereof,~~Agreement ~~Ultragenyx~~and ~~has~~in ~~agreed~~accordance ~~that~~with ~~Purchaser will commence a cash tender offer~~ Section 251(~~the “Offer”~~h) ~~to acquire all~~ of the ~~shares~~Delaware ofGeneral Corporation ~~the~~Law ~~Company’s common stock~~ (“~~Shares~~DGCL”), ~~for~~Purchaser awas ~~purchase~~merged ~~price~~with ofand ~~$6.00~~into ~~per~~the ~~share~~Company, ~~net~~with to the ~~seller~~Company inbeing ~~cash~~the surviving corporation (the “~~Offer Price~~Merger”)~~, without~~. ~~interest,~~Upon ~~subject~~completion toof the ~~terms~~Merger, ~~and~~the ~~conditions~~Company ofbecame ~~the~~a ~~Merger~~wholly-owned ~~Agreement~~subsidiary of Ultragenyx.

~~The~~At ~~Merger~~the ~~Agreement~~effective ~~provides~~time ~~that,~~of ~~following~~ the ~~consummation~~ ofMerger (the ~~Offer~~“Effective Time”), ~~Purchaser~~as ~~will~~a ~~merge~~result ~~with~~of the Merger, and ~~into~~pursuant to the ~~Company~~terms ~~(the~~and ~~“Merger”),~~subject ~~with~~to the ~~Company~~conditions ~~surviving~~of the Merger asAgreement, aeach ~~wholly-owned~~Share ~~subsidiary~~issued ofand ~~Ultragenyx.~~outstanding ~~The~~immediately ~~Merger~~prior ~~will~~to bethe ~~governed~~Effective byTime ~~Section 251(h)~~was ofconverted into the ~~General~~ ~~Corporation~~right ~~Law~~to ofreceive the ~~State~~Offer ofPrice, ~~Delaware~~in cash, ~~with~~without nointerest ~~stockholder~~thereon ~~vote~~and ~~required~~subject to ~~consummate~~any required ~~the~~tax ~~Merger. In the Merger~~withholding, ~~each outstanding Share (~~other than (i) Shares held by the Company as treasury stock, or ~~owned~~ by Ultragenyx, or Purchaser or (ii) Shares held by stockholders who ~~are entitled to demand, and who~~ properly ~~demand,~~exercised appraisal rights under ~~Delaware law) will be converted into~~ the ~~right to receive cash in an amount equal to the Offer Price, without interest~~DGCL.

~~Purchaser~~The ~~has~~effect ~~agreed to commence the Offer as promptly as reasonably practicable from the date~~ of the Merger ~~Agreement~~on ~~(but~~Company instock nooptions ~~event~~and ~~later than~~other equity-based awards ~~five~~is ~~business~~described ~~days~~on ~~from~~pages 4-5 ~~the date~~ of the ~~Merger~~Company’s ~~Agreement).~~Solicitation/Recommendation ~~The~~Statement ~~consummation~~on ofSchedule ~~the~~14D-9 ~~Offer~~filed ~~will~~with bethe ~~conditioned~~SEC on ~~(i)~~October at2, ~~least~~2017, aas ~~majority~~amended ~~of the Shares (calculated~~ on aOctober 11, ~~fully diluted basis in accordance with the Merger Agreement) having been~~2017, ~~validly~~October 12, ~~tendered~~2017, ~~into~~October 17, ~~and not withdrawn from the Offer~~2017, ~~(ii)~~October ~~the~~23, ~~expiration or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 and other applicable antitrust laws~~2017, ~~(iii)~~October ~~the~~26, ~~accuracy~~2017 ~~of the representations~~ and ~~warranties~~October 27, ~~and compliance with the covenants contained in the Merger Agreement~~2017, ~~subject~~which todescription ~~qualifications,~~is ~~and~~incorporated ~~(iv) other~~herein ~~customary~~by ~~conditions~~reference.

InUpon ~~connection~~the ~~with~~closing of the Merger, ~~each outstanding option to purchase Shares will be assumed by~~ Ultragenyx ~~and~~paid ~~converted into an option to acquire a number of shares of Ultragenyx common stock, determined by multiplying~~ the ~~number~~aggregate ofconsideration ~~Shares subject to such option by the Exchange Ratio with a corresponding adjustment to the exercise price~~ of ~~the~~approximately ~~option~~$152.3 million, ~~and~~not ~~each~~including ~~outstanding award of~~related ~~Dimension~~transaction ~~restricted~~fees ~~stock will be assumed by Ultragenyx~~ and ~~converted~~expenses. ~~into an award for a number of shares of~~ Ultragenyx ~~restricted~~provided ~~common~~Purchaser ~~stock~~with ~~determined by multiplying~~ the ~~number~~funds ofnecessary ~~Shares subject~~ to ~~such~~complete ~~award by~~ the ~~Exchange Ratio. The “Exchange Ratio” means the~~ Offer ~~Price~~and ~~divided~~Merger byin ~~the~~accordance ~~volume~~with ~~weighted average of~~ the ~~closing~~Merger ~~sale~~Agreement. ~~prices per share of~~ Ultragenyx ~~common~~funded ~~stock~~these onpayments ~~The~~with ~~NASDAQ~~available ~~Global~~cash ~~Select Market for the five trading days ending~~ on ~~the third business day before Ultragenyx’s acceptance of shares tendered pursuant to the Offer~~hand.

The ~~Merger~~foregoing ~~Agreement~~summary ~~includes~~description ~~representations, warranties and covenants~~ of the ~~parties~~Merger ~~customary~~Agreement ~~for~~does anot ~~transaction~~purport ofto ~~this~~be ~~type,~~complete ~~including,~~and ~~among~~is ~~other~~qualified ~~things,~~in ~~covenants~~its entirety by ~~the~~reference ~~Company~~ to ~~conduct its business in~~ the terms ~~ordinary course during the interim period between the execution~~ of the Merger Agreement, ~~and the~~which ~~consummation~~is ofincluded ~~the~~as ~~Merger~~Exhibit ~~and~~2.1 ~~not~~ to ~~engage~~this inCurrent ~~certain~~Report ~~kinds~~on ofForm ~~transactions~~8-K ~~during such period. The board of directors of the Company has unanimously adopted resolutions recommending that the Company’s stockholders accept the Offer~~ and ~~tender~~ ~~their~~is ~~Shares~~incorporated toherein ~~Purchaser~~by ~~pursuant to the Offer~~reference.

~~The~~Item ~~Merger Agreement may be terminated under certain circumstances, including in specified circumstances in connection with superior proposals, or if the transaction is not consummated by April 9, 2018~~3.01 ~~Upon~~Notice ~~the termination~~ of ~~the~~Delisting ~~Merger~~or ~~Agreement,~~Failure ~~under specified circumstances, the Company will be required~~ to ~~pay Ultragenyx~~Satisfy a ~~termination~~Continued ~~fee~~Listing ofRule ~~$2,850,000~~or ~~and~~Standard; toTransfer ~~reimburse Ultragenyx for the $2,850,000 termination fee paid by Ultragenyx on behalf~~ of ~~Dimension in connection with the termination of the REGENXBIO Merger Agreement (as defined below)~~Listing.

2In connection with the closing of the Merger, the Company (i) notified the NASDAQ Global Market (“NASDAQ”) on November 7, 2017 that the Merger was consummated and (ii) requested that NASDAQ (x) halt trading in the Shares for November 7, 2017 and suspend trading of the Shares effective November 7, 2017 and (y) file with the SEC a Form 25 Notification of Removal from Listing and/or Registration to delist and deregister the Shares under Section 12(b) of the Securities Exchange Act of 1934 (the “Exchange Act”). The Company intends to file a certification on Form 15 with the SEC to cause the Company’s reporting obligations under Sections 13 and 15(d) of the Exchange Act to be suspended.

~~The~~Item assertions embodied in the representations and warranties were made solely for purposes of the contract among the Company and Ultragenyx and may be subject to important qualifications and limitations agreed to by the Company and Ultragenyx in connection with the negotiated terms3.03 ~~Moreover,~~Material ~~some~~Modification ~~of those representations and warranties may not be accurate or complete as of any specified date, may be subject~~ to aRights ~~contractual standard~~ of ~~materiality~~Security ~~different from those generally applicable to stockholders or may have been used for purposes of allocating risk among the Company and Ultragenyx rather than establishing matters as facts~~Holders. Investors are not third-party beneficiaries under the Merger Agreement and should not rely on the representations, warranties and covenants in the Merger Agreement or any description thereof as characterizations of the actual state of facts of the Company, Ultragenyx or any of their respective subsidiaries or affiliates.

~~Completion~~The ofinformation ~~the~~disclosed ~~Merger~~under Item is2.01, ~~anticipated~~Item 3.01, toand ~~occur~~Item in5.01 ~~the fourth quarter~~ of ~~2017,~~this ~~although~~Current ~~there~~Report ~~can~~on beForm no8-K ~~assurance~~is ~~the~~incorporated ~~Merger~~by ~~will~~reference ~~occur within~~into ~~the~~this ~~expected~~Item ~~time frame or at all~~3.03.

~~This~~Item summary of the principal terms of the Merger Agreement and the copy of the Merger Agreement filed as an exhibit to this Form 8-K are intended to provide information regarding the terms of the Merger Agreement and are not intended to modify or supplement any factual disclosures about the Company in its public reports filed with the SEC5.01 InChanges particular, the Merger Agreement and the related summary are not intended to be, and should not be relied upon as, disclosures regarding any facts and circumstances relating to the Company. The foregoing description of the Merger and the Merger Agreement does not purport to be complete and is qualified in ~~its~~Control ~~entirety by reference to the full text~~ of ~~the Merger Agreement, a copy of which is filed as an exhibit to this Form 8-K and is incorporated into this report by reference~~Registrant.

~~Item~~As ~~1.02.~~a ~~Termination~~result of Purchaser’s acceptance for payment of all Shares that were validly tendered and not properly withdrawn in accordance with the terms of the Offer and the consummation of the Merger pursuant to Section 251(h) of the DGCL on November 7, 2017, a ~~Material~~change ~~Definitive~~in ~~Agreement~~control of the Company occurred and the Company now is a wholly-owned subsidiary of Ultragenyx.

OnThe ~~October 2,~~information ~~2017,~~disclosed ~~prior~~under toItem ~~entering into the Merger Agreement with Ultragenyx, the Company terminated the Agreement and Plan of Merger, dated as of August 24, 2017, by and among REGENXBIO Inc~~2.01 ~~(“REGENXBIO”), Muddy Charles Acquisition Corporation~~ and the Company (the “REGENXBIO Merger Agreement”). The REGENXBIO Merger Agreement was terminated due to the superior proposal (within the meaning of the REGENXBIO Merger Agreement) made by Ultragenyx as disclosed above under Item 13.01 of this Current Report on Form 8-K. ~~In connection with the termination of the REGENXBIO Merger Agreement, Ultragenyx~~ is ~~paying~~incorporated ~~REGENXBIO~~by ~~the~~reference ~~$2,850,000~~into ~~termination~~this ~~fee~~Item ~~due under the REGENXBIO Merger Agreement on behalf of the Company~~5.01.

Item 85.~~01.~~02 ~~Other~~Departure ~~Events~~of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

~~On October 3,~~In ~~2017,~~connection with the ~~Company~~Merger, ~~and~~each ~~Ultragenyx~~of ~~issued~~Annalisa aJenkins, ~~joint~~Alan ~~press~~Colowick, ~~release~~Michael ~~announcing~~Dybbs, ~~among~~Georges ~~other~~Gemayel, ~~things~~George Migausky, ~~the~~John ~~execution~~Hohneker and Arlene Morris resigned from his/her respective position as a member of the ~~Merger~~Board ~~Agreement. A~~of ~~copy~~Directors, and any committee thereof, of the ~~press~~Company, ~~release~~and isany ~~attached~~Subsidiary ~~hereto~~of the Company, as ~~Exhibit 99.1~~applicable, ~~and~~effective isat ~~hereby~~the ~~incorporated into~~Effective ~~this~~Time ~~report~~on byNovember 7, ~~reference~~2017.

~~Item~~Following ~~9.01.~~the ~~Financial~~Merger ~~Statements~~and pursuant to the terms of the Merger Agreement, at the Effective Time on November 7, 2017, the director and officers ~~Exhibits~~of Purchaser immediately prior to the Effective Time became the director and officers of the Company following the Effective Time, with Thomas Kassberg appointed as President of the Company, Shalini Sharp appointed as Vice President and Treasurer of the Company, and Karah Parschauer appointed as director, Vice President and Secretary of the Company.

Information about Mr. Kassberg, Ms. Sharp and Ms. Parschauer is contained in the Offer to Purchase, dated October 10, 2017, filed by Ultragenyx and Purchaser as Exhibit (da) ~~Exhibits~~(1)(A) to the Tender Offer Statement on Schedule TO, originally filed with the SEC on October 10, 2017, which information is incorporated herein by reference.

Exhibit No.		Description
2.1		Agreement and Plan of Merger, dated as of October 2, 2017, by and among Dimension Therapeutics, Inc., Ultragenyx Pharmaceuticals Inc. and Purchaser.*
99.1		Joint press release issued on October 3, 2017 by Dimension Therapeutics, Inc. and Ultragenyx Pharmaceuticals Inc.

Item 5.03

Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year.

*At ~~Schedules~~the ~~have~~Effective ~~been~~Time, ~~omitted~~the ~~pursuant~~Company’s tocertificate ~~Item 601(b)(2)~~ of ~~Regulation~~incorporation ~~S-K. Dimension~~and ~~Therapeutics,~~bylaws ~~Inc.~~were ~~hereby~~amended ~~undertakes~~and torestated ~~furnish~~in ~~supplemental~~their ~~copies~~entirety. Copies of ~~any~~the Company’s amended and restated certificate of incorporation and the ~~omitted~~Company’s ~~schedules~~amended ~~upon~~and ~~request~~restated bybylaws are ~~the~~attached ~~SEC~~as Exhibits 3. 1 and 3.2, respectively, hereto, each of which are incorporated herein by reference.

3Item 8.01 Other Events.

~~Forward-Looking~~On ~~Statements~~November 7, 2017, Ultragenyx issued a press release relating to the expiration of the Offer and the consummation of the Merger. A copy of the press release is attached as Exhibit 99.1 hereto and is incorporated herein by reference.

~~Any~~Item statements made in this communication that are not statements of historical fact, including statements about the expected timetable for completing the transaction and the Company’s beliefs and expectations and statements about the tender offer and Ultragenyx’s proposed acquisition of the Company, including the timing of and closing conditions to the acquisition, and the potential effects of the acquisition on both Ultragenyx and the Company are forward-looking statements that are based on management’s beliefs, certain assumptions and current expectations and should be evaluated as such9.01 ~~These~~Financial ~~statements~~Statements ~~may be identified by their use of forward-looking terminology such as the words “expects,” “projects,” “anticipates,” “intends”~~ and ~~other similar words~~Exhibits. Forward-looking statements include statements that may relate to Ultragenyx’s or the Company’s plans, objectives, strategies, goals, future events, future revenues or performance, and other information that is not historical information. Such forward-looking statements involve risks and uncertainties that could cause actual results to differ materially from those projected. These risks and uncertainties include, but are not limited to, general economic, business and market conditions and the satisfaction of the conditions to closing of the proposed transaction. For a more complete discussion of certain of the risks and uncertainties that could cause actual results to differ from those contained in the forward-looking statements with respect to the Company, see the discussion of risks and uncertainties in the Company’s annual report on Form 10-K, quarterly reports on Form 10-Q and other documents filed by Dimension from time to time with the SEC. The forward-looking statements contained in this report are made as of the date hereof, and the Company undertakes no obligation to update any forward-looking statements, whether as a result of future events, new information or otherwise, except as required by law.

~~Important~~(d) ~~Information~~Exhibits.

The tender offer for the outstanding Shares referred to in this document has not yet commenced. This communication is for informational purposes only and is neither an offer to purchase nor a solicitation of an offer to sell Shares, nor is it a substitute for the tender offer materials that Ultragenyx and its acquisition subsidiary will file with the SEC upon commencement of the tender offer. At the time the tender offer is commenced, Ultragenyx and Purchaser will cause to be filed a tender offer statement on Schedule TO with the SEC, and the Company will file a solicitation/recommendation statement on Schedule 14D-9 with respect to the offer. THE TENDER OFFER STATEMENT (INCLUDING AN OFFER TO PURCHASE, A RELATED LETTER OF TRANSMITTAL AND OTHER OFFER DOCUMENTS) AND THE SOLICITATION/RECOMMENDATION STATEMENT WILL CONTAIN IMPORTANT INFORMATION THAT SHOULD BE READ CAREFULLY AND CONSIDERED BY THE COMPANY’S STOCKHOLDERS BEFORE ANY DECISION IS MADE WITH RESPECT TO THE TENDER OFFER. Both the tender offer statement and the solicitation/recommendation statement will be mailed to the Company’s stockholders free of charge. A free copy of the tender offer statement and the solicitation/recommendation statement will also be made available to all stockholders of the Company by accessing Dimension’s website at www.dimensiontx.com or upon written request to Dimension Therapeutics, Inc., 840 Memorial Drive, Cambridge, Massachusetts 02139. In addition, the tender offer statement and the solicitation/recommendation statement (and all other documents filed with the SEC) will be available at no charge on the SEC’s website: www.sec.gov, upon filing with the SEC.


Exhibit Number		Title

2.1		Agreement and Plan of Merger, dated as of October 2, 2017, by and among Dimension Therapeutics, Inc., Ultragenyx Pharmaceutical Inc. and Mystic River Merger Sub Inc. (incorporated by reference to Exhibit 2.1 of the Company’s Current Report on Form 8-K filed with the SEC on October 3, 2017)

3.1		Amended and Restated Certificate of Incorporation of Dimension Therapeutics, Inc.

3.2		Amended and Restated Bylaws of Dimension Therapeutics, Inc.

99.1		Press Release of Ultragenyx Pharmaceutical Inc., dated November 7, 2017

~~THE~~SIGNATURES COMPANY’S STOCKHOLDERS ARE ADVISED TO READ THE SCHEDULE TO AND THE SCHEDULE 14D-9, AS EACH MAY BE AMENDED OR SUPPLEMENTED FROM TIME TO TIME, AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC WHEN THEY BECOME AVAILABLE BEFORE THEY MAKE ANY DECISION WITH RESPECT TO THE TENDER OFFER, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED TRANSACTION AND THE PARTIES THERETO.

4Pursuant 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.

SIGNATURES

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.

	DIMENSION THERAPEUTICS, INC.
Dated: October 3, 2017	By:	/s/ Mary Thistle
		Name:	Mary Thistle
		Title:	Chief Operating Officer

Dimension Therapeutics, Inc.

November 7, 2017

/s/ Karah Parschauer

Karah Parschauer

Vice President and Secretary

Filing Compare · Dimension Therapeutics, Inc.