Shares of Celladon Corporation (CLDN) are down 70% after the company reported that Mydicar treatment failed to meet on both the primary endpoint and secondary endpoint of the study. The trial known as Cupid 2 was a phase 2b study and recruited up to 250 patients in total. The trial was testing therapy of Mydicar versus a  placebo compound. 

Mydicar is a drug known as gene therapy that is built to replace a missing gene that can build a protein known as SERCA2a in heart-failure patients.

SERCA 2 is known to help the heart muscles expand and pump blood more efficiently. The Mydicar therapies goal was to eventually bring the SERCA2 enzyme to normal levels, which is not seen in heart-failure patients. 

The primary endpoint was time to recurrent heart failure events -- heart failure related hospitalizations or ambulatory treatment for worsening heart failure.

The secondary endpoint was time to first terminal event -- all cause death, heart transplant or placement of a circulatory support device. The company failed to meet on both these endpoints against the placebo compound. Even worse, the Mydicar therapy failed to show any improvements over placebo in other exploratory endpoints such as: 

1. Improvement in Heart Association Classification
2. 6-minute walk test 
3. Quality of life

Right now the company seems to have a dim future because Mydicar consists of the company's main pipeline. Other drug compounds for Mydicar are also being tested in other heart diseases. This means that Mydicar may not provide sufficient efficacy going forward in other heart indications, leaving investors stranded. The company does have other treatments in pre-clinical and phase 1 testing, using stem cells and small molecules but those are too early to tell and it could be many years out for the company to initiate trials on those. 

This trial failure was not only a blow to Celladon but it could possibly be a huge blow to other gene therapy companies like Bluebird Bio (BLUE), Spark Therapeutics (ONCE), and UniQure (QURE). All these other companies are also working on replacing faulty genes with new ones in hopes of altering diseases. The good news is that not all gene therapies have the same technology in doing so, therefore Celladon's Mydicar might have been a single event. In any case we would say that it is best to stay clear of Celladon as the company won't have value until it enters clinical trials with other products.