Discontinues Clinical Development of DTX101, an AAVrh10 Factor IX Gene Therapy Product Candidate for Moderate/Severe-to-Severe Hemophilia B
Initial data from Phase 1/2 clinical trial of DTX301, Dimension’s lead AAV8 vector IMD product candidate for OTC Deficiency, expected 2H 2017

CAMBRIDGE, MA, USA I May 10, 2017 I Dimension Therapeutics, Inc. (NASDAQ:DMTX), a biopharmaceutical company advancing novel, adeno-associated virus (AAV) gene therapies targeting the liver, a key organ for human metabolism, today reported financial results for the first quarter ended March 31, 2017, and provided a corporate update.

The company announced its decision to discontinue the development of DTX101, an investigational AAVrh10-based gene therapy product in development for the treatment of moderate/severe-to-severe hemophilia B. The decision followed the review of the emerging DTX101 Phase 1/2 clinical study data, including the data as of the beginning of May 2017, and the observation that the data would not meet the company’s minimum target product profile for continued development or future commercialization. Dimension plans to present full study findings, including results from ongoing immune and biomarker analyses, at a future scientific conference.

“We are disappointed with the outcome of our DTX101 program, addressing an important disease with significant unmet need; however, our Phase 1/2 open-label clinical study did not demonstrate an ability to achieve a minimum target product profile for continued development or future commercialization,” said Annalisa Jenkins, MBBS, FRCP, Chief Executive Officer of Dimension. “We deeply appreciate the participation by the investigators and staff, patients and caregivers who all contributed to the conduct and execution of this Phase 1/2 clinical trial. Further, Dimension remains committed to the hemophilia community through continued investment in the Company’s ongoing IND-enabling activities for DTX201 for hemophilia A, in collaboration with Bayer, and the follow-up of the six patients dosed with DTX101 in the Phase 1/2 clinical trial through an extension study that will monitor all patients for a total of five years.”

Dr. Jenkins continued, “We remain excited about the opportunities around our IMD portfolio, which, unlike DTX101, utilizes the AAV8 capsid, and look forward to initial data later this year with DTX301 for OTC deficiency.” The company does not believe the outcome of the DTX101 program will affect the ongoing Phase 1/2 clinical development of DTX301, Dimension’s lead AAV8-based gene therapy, in OTC deficiency, or current vector design for the company’s other investigational AAV therapeutic programs in development. While the company remains focused on the development of our IMD programs testing AAV8 based vectors, it will be undertaking a comprehensive portfolio prioritization review to thoroughly examine resources and the opportunities to focus efforts, which review is expected to be completed by the end of the second quarter of 2017.

Recent Highlights and Upcoming Milestones

– Inherited Metabolic Disease (IMD) Programs –

•  Continued to advance robust portfolio of IMD candidates utilizing the capsid serotype AAV8 – DTX301 for OTC deficiency, DTX401 for GSDIa, DTX501 for PKU, DTX701 for Wilson disease, and DTX601 for citrullinemia type I:

  • DTX301: Initiated a multi-center Phase 1/2 open-label study for lead IMD candidate DTX301 in December 2016. Two sites open and expect to disclose initial data from the trial in the second half of 2017.
    –  Trial includes assessment of 13C-acetate to evaluate rate of ureagenesis and hepatocyte (liver) ureagenesis capacity.
  • DTX401: Advancing IND-enabling activities to support an IND filing for DTX401 by the end of 2017.
  • DTX501, DTX701, DTX601: Ongoing nonclinical activities supporting selection of development candidates for Wilson disease (DTX701) and for PKU (DTX501) in 2H 2017 and for citrullinemia type I (DTX601) in the next 12-18 months.

– Hemophilia A –

•  DTX201: Currently in IND-enabling studies in collaboration with Bayer for the treatment of moderate/severe to severe hemophilia A.

  • IND filing for DTX201 expected by the end of 2017.

First Quarter 2017 Financial Results

  • Cash Position: Cash, cash equivalents and marketable securities as of March 31, 2017 were $59.1 million.  The Company expects its existing cash, cash equivalents, and marketable securities, and reimbursements and milestones to be received in connection with its collaboration agreement with Bayer, and borrowing capacity under its loan and security agreement will enable it to fund its operating expenses and capital expenditure requirements through mid-2018. 
      
  • Revenue: For the quarter ended March 31, 2017, the Company recognized $3.6 million of revenue associated with its collaboration agreement with Bayer compared to $2.2 million for the same period in 2016. The increase was due to services performed in connection with the Company’s performance obligations under its collaboration agreement with Bayer. 
      
  • R&D Expenses: Research and development expenses for the quarter ended March 31, 2017 were approximately $13.7 million compared to $8.8 million for the same period in 2016. The increase was primarily due to increased expenditures in manufacturing and clinical activities.
      
  • G&A Expenses: General and administrative expenses for the quarter ended March 31, 2017 were approximately $3.4 million compared to $2.9 million for the same period in 2016. The increase was primarily due to increased non-cash stock-based compensation expense.
      
  • Net Loss: For the quarter ended March 31, 2017, the Company reported a net loss of $(13.5) million, or $(0.54) per share, compared to a net loss of $(9.5) million, or $(0.38) per share, for the same period in 2016.
      
  • Shares Outstanding: As of March 31, 2017, the Company had approximately 25.0 million common shares issued and outstanding.

About Dimension Therapeutics, Inc.

Dimension Therapeutics, Inc. (NASDAQ:DMTX) is a leader in discovering and developing new therapeutic products for people living with devastating rare and metabolic diseases associated with the liver, based on the most advanced mammalian adeno-associated virus (AAV) gene delivery technology. Dimension is actively progressing its broad pipeline, which features programs addressing unmet needs for patients suffering from inherited metabolic diseases, including OTC deficiency, GSDIa, citrullinemia type 1, PKU, Wilson disease, and a collaboration with Bayer in hemophilia A. Dimension has initiated a phase 1/2 clinical trial with DTX301 for the treatment of OTC deficiency. The company targets diseases with readily identifiable patient populations, highly predictive preclinical models, and well-described, and often clinically validated, biomarkers. Founded in 2013, Dimension maintains headquarters in Cambridge, Massachusetts.

SOURCE: Dimension Therapeutics