8-K

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): August 11, 2016

Dimension Therapeutics, Inc.

(Exact name of registrant as specified in its charter)

DELAWARE	001-37601	46-3942159
(State or other jurisdiction of incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)

840 Memorial Drive, 4th Floor Cambridge, MA	02139
(Address of principal executive offices)	(Zip Code)

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))

Item 7.01. Regulation FD Disclosure.

On August 11, 2016, Dimension Therapeutics, Inc. (the “Company”), intends to deliver a corporate presentation at the Canaccord Genuity 36th Annual Growth Conference at 12:30 p.m. EST, during which the Company will present certain slides (the “Presentation”). A copy of the Presentation is furnished hereto as Exhibit 99.1 to this Current Report on Form 8-K

The information in this Item 7.01 and Exhibit 99.1 attached hereto shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that section, nor shall they be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, except as expressly set forth by specific reference in such filing.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.	Description
99.1	August 11, 2016 Company presentation at the Canaccord Genuity 36th Annual Growth Conference, furnished herewith.

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.

Date: August 11, 2016	DIMENSION THERAPEUTICS, INC.
	By:	/s/ Jean Franchi
		Jean Franchi
		Chief Financial Officer

EX-99.1

Exhibit 99.1

Dimension Therapeutics, Inc.

Quality of Science. Quality of Life.

August 2016

Forward Looking Statements

These slides and the accompanying oral presentation contain forward-looking statements and information. The use of words such as “may,” “might,” “will,” “should,” “expect,” “plan,” “anticipate,” “believe,” “estimate,” “project,” “intend,” “future,” “potential,” or “continue,” and other similar expressions are intended to identify forward looking statements. For example, all statements we make regarding the initiation, timing, progress and results of our preclinical and clinical studies and our research and development programs, our ability to advance product candidates into, and successfully complete, clinical studies, the timing or likelihood of regulatory filings and approvals, our ability to develop manufacturing processes and engage third parties to manufacture our product candidates for late-stage clinical use or at commercial scale, the success of strategic partnerships, if any, and our expected cash, cash equivalents and marketable securities at year end are forward looking. All forward?looking statements are based on estimates and assumptions by our management that, although we believe to be reasonable, are inherently uncertain. All forward-looking statements are subject to risks and uncertainties that may cause actual results to differ materially from those that we expected. These statements are also subject to a number of material risks and uncertainties that are described under the caption “Risk Factors” in Dimension Therapeutics’ Quarterly Report on Form 10-Q for the quarter ended June 30, 2016, which is on file with the Securities and Exchange Commission, as well as other risks detailed in

Dimension Therapeutics’ additional filings with the Securities and Exchange Commission. Any forward?looking statement speaks only as of the date on which it was made. We undertake no obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events or otherwise, except as required by law.

The information contained in this presentation is not an offer to sell or the solicitation of an offer to buy the

Company’s common stock or any other securities of the Company.

© 2016 Dimension Therapeutics

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Dimension Therapeutics

A leader in    Robust scientific gene therapy platform

discovering &    Manufactured using mammalian process

developing new    Deep expertise in liver biology

therapeutics for    Unique focus on inherited metabolic diseases (IMDs)

people living with    

devastating rare    Highly experienced team; extensive track record in

diseases    rare diseases

associated with    

the liver    Broad product pipeline addressing diseases with high

unmet medical need

© 2016 Dimension Therapeutics

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Clade E AAV-Based Gene Therapy Product Platform

Enhanced liver affinity; 16-110x greater liver targeting than other AAVs

Clade E Family of    • Durable expression achieved in 5-10% hepatocytes

AAV Capsids    • Well-established safety profile for use in human gene therapy

~25% of the population may be ineligible due to neutralizing antibodies

Proprietary    • Mammalian cell-based system to leverage AAV biology

Industrialized    • Scalable HeLa platform to optimize yield and quality

Manufacturing    

Downstream process consistent with biologic and antibody standards

Approach    

Source: Gao et al. 2004 J Virol; Fagiuoli et al. 2013 J Hepat

© 2016 Dimension Therapeutics

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Robust AAV Capsid and Transgene IP Estate

Capsid Intellectual Property    

    Transgene Intellectual

Exclusive, worldwide license to certain REGENXBIO    Property

AAV vector technology spanning various serotypes    

in up to 8 specified disease indications    1RGNX in-license

    includes patent

    +application directed to

Exclusive Disease Indications    codon-optimized

2013 License    2015 Option & Licenseversion of the OTC gene

Hemophilia A*    2Citrullinemia Type 1

Hemophilia B*    2PKU2Exclusive WW

1    OTC Deficiency 2Wilson Diseasecollaboration and

    license agreement with

GSDIa    Option 1**UPENN

*License excludes AAV8 for hemophilia A or B; **Option to license rights to REGENXBIO AAV technology for    

any 1 additional disease, subject to availability (diseases not licensed in whole or in part to a 3rd party)    

© 2016 Dimension Therapeutics

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The Liver is a Central Organ for Rare Diseases

>400 Described Rare Monogenic Diseases Associated with the Liver    

Subset Believe Well-Suited to Gene Therapy    

Hemophilia     Urea Cycle Disorders

    Well-understood disease biology

    Restoration to 5-10% of normal is

    clinically meaningful

Storage Disorders     Highly predictive preclinical modelsAminoacidopathies

    Well-described biomarkers

    Potential orphan drug designation

Source: Fagiuoli    et al. 2013 J Hepat; carolguze.com/text/442-11-clinical_genetics.shtml; DMTX analyses; surgery.usc.edu/hepatobiliary/liversurgery.html

    © 2016 Dimension Therapeutics6

Broad Product Pipeline Addressing Diseases with Significant Medical Need

© 2016 Dimension Therapeutics 7

Pipeline Set to Deliver Major Development Milestones in Next 18 Months

    Advancing 7 Program Portfolio

Hem B available data*•OTC initial data

File OTC IND•Hem B additional data

Value    • Initiate OTC ph I/II clinical trial•File GSDIa IND

GSDIa US orphan designation•GSDIa EU orphan designation

OTC EU orphan designation    •Hem A IND enabling studies

Expanded IMD portfolio    •Citrullinemia type 1, PKU,

    Wilson Disease development

    candidates

    201612-18 Months

© 2016 Dimension Therapeutics *All patients at 8 weeks post-dosing at time of presentation 8

Inherited Metabolic Disease Programs

© 2016 Dimension Therapeutics 9

Ornithine Transcarbamylase (OTC) Deficiency

Disease    Patient Population

X-linked, urea cycle disorder (UCD)~10,000 patients WW

Genetic defect in ammonia~80% late onset

detoxification    

Adverse cognitive & neurological•Most common UCD, ~55%

effects, coma, death    

Treatments limited, non-curative•Severe, early onset in males

    •Late onset in males & females

Sources: National Urea Cycles Disorder Foundation; NORD; Batshaw et al. Mol Gen Metab 2014; Tuchman et al 2008; Enns N Engl J Med 2007; Foschi et al. World J Gastro ESPS Manuscript no: 13209; carolguze.com/text/442-11-clinical_genetics.shtml; Dimension Therapeutics unpublished data

© 2016 Dimension Therapeutics

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DTX301: Replace OTC to Address Toxic Hyperammonemia

Well understood disease biology;    Well-described Path to HPOC

highly predictive preclinical models    Biomarkers Defined

• Serum ammonia    

Durable Expression of Functional OTC in spf ash OTC Mouse    • Urinary orotic acid • Granted orphan drug

    designation (US/EU)

• Excess carbamoyl    • hPOC serum ammonia

phosphate converted    

to orotic acid    • Adult males and at-risk

• Increased serum    females

ammonia; neurotoxic    

Source: Dimension Therapeutics unpublished data

© 2016 Dimension Therapeutics

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Glycogen Storage Disease Type Ia (GSDIa)

Disease    Patient Population

Autosomal recessive, inborn error of~6,000 patients WW

glucose metabolism    Dx at birth

Deficient glucose-6-phosphatase

(G6Pase)    

Reduced QOL, long term risks•Most common GSD, ~25%

Strict diet and frequent feedings of•No approved drug therapies

uncooked starch or Glycosade®    

Sources: Weinstein et al. Hum Gen Ther 2010; Lee et al. Hepatology 2012; Chou et al Nat Rev Endo 2010; Boers et al. Orphanet Journal of Rare Diseases 2014; www.curegsd.org; The Children’s Fund for GSD Research

© 2016 Dimension Therapeutics

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DTX401: Replace G6Pase to Address Life-Threatening Hypoglycemia

Well understood disease biology;    Well-described Path to HPOC

highly predictive preclinical models    Biomarkers Defined

• Single dose AAV8 gene therapy increases G6Pase    • Blood glucose

• Corresponding reduction in hepatic glycogen    • Glycogen stores • hPOC time to

    hypoglycemia

Improved G6Pase Activity in Canines    

• Glycogen build up in    • Adult males and

liver    females

• Inability to release    

glucose, raises risk of    

hypoglycemia    

Sources: Weinstein et al. Hum Gen Ther 2010; Lee et al. Hepatology 2012; Chou et al Nat Rev Endo 2010; Boers et al. Orphanet Journal of Rare Diseases 2014; www.curegsd.org; The Children’s Fund for GSD Research

© 2016 Dimension Therapeutics 13

Broad Inherited Metabolic Disease Portfolio

    Well understood disease biology;Well-describedProduct

    highly predictive preclinical modelsBiomarkersOpportunity

Wilson    • Autosomal recessive copper disorder•WW prevalence >50K

Disease    • Deficiency in copper transporter P-• Copperpatients

    type ATPase

Autosomal recessive disorder•~50K prevalent patients

PKU     • Phenylalanine

Deficiency in phenylalanine hydrolasedeveloped world

Autosomal recessive UCD

Citrullinemia     •14% of all UCDs

Deficiency in argininosuccinate• Ammonia

Type 1     •WW prevalence ~2K

    synthetase

Sources: Barends MGM 2014; Batshaw MGM 2014; Citrullinemia Type I NCBI Bookshelf; Engel et al Hum Mut 2009; Foschi World J Gastro 2015; Marti?n-Herna?ndez Orph J Rare Dis 2014; NORD; Ruder Ped Neuro 2014; Ruegger J Inherit Metab Dis 2014; Summar Acta Paediatr. 2008; Summar Crit Care Clin 2005; Tuchman et al Mol Genet Metab 2008; Berry Genet Med 2013; Hanley J Genet Disor Genet Rep 2013; Vockley Gen Med 2014; Zerjav Orph J Rare Dis 2015; Beinhardt Clin Gast Hepat 2014; Bull Nat Gen 1993; EASL Prac Guide; Gomes Ann Hum Bio 2015; Kaler Nat Rev Neurol 2011; Roberts & Schilsky Hepat 2008; Schilsky Biochimie 2009; WD Pathogenesis Semin Liver Dis 2000

© 2016 Dimension Therapeutics 14

Hemophilia Programs

© 2016 Dimension Therapeutics 15

~$6.2B WW Market for Hemophilia B and A Products

Disease    Patient Population

Deficiency of blood coagulation~28,000 Hem B patients WW

factor IX (FIX) or factor VIII (FVIII)    ~140,000 Hem A patients WW

Joint hemorrhages, potential for

severe disabilities; brain micro-    •~68% Hem B, 78% Hem A

bleeds    moderate to severe disease

Frequent, invasive, non-curative

infusions of factor replacement    •$100,000-$300,000 annual costs

    per patient

Sources: Riley et al. Haemophilia 2011; National Hemophilia Foundation; World Federation of Hemophilia; www.fiercepharmamarketing.com/story/biogens-alprolix-nod-just-first-tremor-hemophilia-market-shake/2014-04-02; Stonebraker et al. Haemophilia (2011), 1–4; Baker et al. Haemophilia (2012); Stonebraker et al. Haemophilia (2010), 16, 20–32; National Hemophilia Foundation; www.ptcommunity.com/news/2014-12-29-000000/hemophilia-market-likely-undergo-major-changes; Johnson and Zhou. ASH Annual Meeting Educational Program. 2011; Ponder. Haemophilia 2008; Manco-Johnson et al. NEJM 2007

© 2016 Dimension Therapeutics 16

DTX101 for Hemophilia B

DTX101     Phase I/II Study Ongoing

• Vector capsid Clade E AAVrh10    • Open-Label, safety, dose finding study

• Gene cassette wild type factor IX    • Bayesian adaptive design

• Liver specific enhancer-promoter    • Primary endpoints safety & FIX activity

• HEK293 process for hPOC    • Up to 12 males with moderate/severe to

    severe Hem B (?2% FIX levels)

• TPP* targeting stable FIX activity >10%    

Dosing: 1.6e12-1e13 GC/kg, single

• Reduce dependency for on demand &     peripheral venous infusion

prophylactic FIX therapies    

Cohort 1 dosing complete

© 2016 Dimension Therapeutics * TPP: Target Product Profile 17

DTX201: Global Collaboration with Bayer

Hemophilia A    

A leading gene therapy     Global leader in hemophilia

company     drug development and

    commercialization

• $20M upfront, up to $232M in milestones    

• High single-digit to low double-digit royalties not exceeding the mid-teens

• R&D expense reimbursement    

• DMTX responsible for preclinical    activities and Phase I/II clinical trial, funded by Bayer

• Bayer to fund subsequent trials and commercial activities at clinical POC

© 2016 Dimension Therapeutics 18

DTX201: Durable FVIII Expression in NHPs

DTX201 for Hem A     IND-enabling Studies Ongoing

hFVIII Expression in Non Human Primates    • Seven male cynomolgus macaques

    administered IV with 1.2e13 GC/kg

Sustained FVIII expression in NHPs beyond

    60 weeks

3 of 5 animals retain expression greater

    than 16 weeks; 2 of 7 beyond 34 weeks

Sustained RNA expression

Reduced incidence of anti-FVIII inhibitors

Sources: DMTX-PENN data (ASGCT 2016, EHA 2016)    

© 2016 Dimension Therapeutics 19

Dimension: A Leader in Liver Directed Gene Therapy

Advancing Product Portfolio    Broad 7 program pipeline delivering multiple near-term

milestones

Focus on Inherited Metabolic Diseases    Addressing severe, debilitating unmet medical need

Building Gene Therapy Product Platform    Investing in scalable, quality HeLa manufacturing

Highly Experienced Team    Strong R&D and manufacturing capabilities

Well-Capitalized    Expected cash runway through 1Q 2018

© 2016 Dimension Therapeutics 20

Dimension Therapeutics, Inc.

Quality of Science. Quality of Life.

August 2016