Celladon Reports Negative Results for CUPID2 Trial of MYDICAR(R) in Advanced Heart Failure

- Investigational gene therapy fails to meet primary and secondary endpoints -

- Investor conference call and webcast Monday at 8:30 a.m. ET (5:30 a.m. PT) -

SAN DIEGO, April 26, 2015 -- Celladon Corporation (CLDN) today announced that its Phase 2b CUPID2 trial did not meet its primary and secondary endpoints. CUPID2 is a randomized, double-blind, placebo-controlled, multinational trial evaluating a single, one-time, intracoronary infusion of the cardiovascular gene therapy agent MYDICAR(R)(AAV1/SERCA2a) versus placebo added to a maximal, optimized heart failure drug and device regimen.

In the study, the primary endpoint comparison of MYDICAR to placebo resulted in a hazard ratio of 0.93 (0.53, 1.65 95%CI) (p=0.81), defined as heart failure-related hospitalizations or ambulatory treatment for worsening heart failure. The secondary endpoint comparison of MYDICAR to placebo, defined as all-cause death, need for a mechanical circulatory support device, or heart transplant, likewise failed to show a significant treatment effect. The efficacy endpoint analyses were performed on the (n=243) modified intent to treat population (mITT), which excludes clinical events that occurred in patients who did not receive MYDICAR or placebo, or which occurred prior to dosing. All other exploratory efficacy endpoints (improvement in New York Heart Association classification, 6 Minute Walk Test, and Quality of Life) were also inconsistent with a treatment effect. No safety issues were noted.

"We are surprised and very disappointed that MYDICAR failed to meet the endpoints in the CUPID2 trial, and we are rigorously analyzing the data in an attempt to better understand the observed outcome. We would like to express our sincere gratitude to our investigators and patients who participated in the study," said Krisztina Zsebo, Ph.D., CEO of Celladon. "At the same time we are evaluating our other programs in order to determine the best path forward to maximize shareholder value."

"This trial was extremely well executed and adequately tested the hypothesis, but the therapy failed to achieve the primary and secondary endpoints. However, there were no safety issues," said Barry Greenberg, M.D., FACC, Director, Advanced Heart Failure Treatment Program; Distinguished Professor of Medicine, University of California, San Diego, and the Chairman of the Executive Clinical Steering Committee of the CUPID2 trial.

About the CUPID2 Study

CUPID2 is a Phase 2b, randomized, double-blind, placebo-controlled, multinational trial evaluating a single intracoronary infusion of the cardiovascular gene therapy agent MYDICAR versus placebo added to a maximal, optimized heart failure regimen. The study included 250 adult patients who had stable NYHA (New York Heart Association) class II to IV ischemic or non-ischemic heart failure despite optimal therapy, reduced left ventricular ejection fraction (<= 35%) and a high risk for recurrent heart-failure hospitalizations. CUPID2 enrolled only patients with heart failure with reduced ejection fraction (HF-REF). The statistical analysis for the primary endpoint was performed on the modified intent to treat population (mITT), comprising all patients who, after randomization, underwent cardiac catheterization and drug or placebo administration.

The primary endpoint was time to recurrent heart failure related events (defined as heart failure-related hospitalizations or ambulatory treatment for worsening heart failure), using a statistical analysis methodology called joint frailty modeling. The secondary efficacy endpoint was time to first terminal event (defined as all-cause death, heart transplant or placement of a mechanical circulatory support device), analyzed simultaneously with the primary endpoint using joint frailty modeling.

Conference Call & Webcast

Management will host an investment community conference call to discuss the information in this press release.

Monday, April 27, 2015 @ 8:30 am Eastern Time/5:30 am Pacific Time
Domestic: (855) 455-6053
International: (484) 756-4307
Conference ID: 32771111
Webcast: http://ir.celladon.com/events.cfm
   
Replays -- Available through May 4, 2015
Domestic: (855) 859-2056
International: (404) 537-3406
Conference ID: 32771111

About Celladon Corporation

Celladon is a clinical-stage biotechnology company applying its leadership position in the field of cardiovascular gene therapy to develop novel therapies for diseases with high unmet medical needs. Our lead programs target SERCA enzymes, which are a family of enzymes that play an integral part in the regulation of intra-cellular calcium in all human cells. Calcium dysregulation is implicated in a number of important and complex medical conditions and diseases, such as heart failure, vascular disease, diabetes and neurodegenerative diseases. The company conducts research and development on its mSCF gene therapy program for cardiac diseases. Celladon has also identified a number of potential first-in-class compounds addressing novel targets in diabetes and neurodegenerative diseases with its small molecule platform of SERCA2b modulators. For more information, please visit www.celladon.com.

Forward-Looking Statements

Statements contained in this press release regarding matters that are not historical facts are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements include, but are not limited to, statements regarding Celladon's future plans with respect to the development of MYDICAR for heart failure and its other programs, as well as its plan to determine the best path forward to maximize shareholder value. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. These forward-looking statements are based upon Celladon's current expectations and involve assumptions that may never materialize or may prove to be incorrect. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of various risks and uncertainties, which include, without limitation, risks and uncertainties associated with viral manufacturing processes and other product development activities, clinical trials and obtaining regulatory approval to commercialize product candidates, our reliance on third parties, the need to raise additional funding when needed in order to conduct our business, and the degree of market acceptance of our product candidates by physicians, patients, third-party payors and others in the medical community. These and other risks and uncertainties are described more fully in Celladon's filings with the Securities and Exchange Commission, including without limitation its Form 10-K for the year ended December 31, 2014. All forward-looking statements contained in this press release speak only as of the date on which they were made. Celladon undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.

Contact:
Fredrik Wiklund
Vice President, Corporate Development & Investor Relations
(858) 432-7215