Celladon Corporation, which is developing a first-in-class gene therapy for patients with systolic heart failure, postponed its IPO on Wednesday, citing poor market conditions. The San Diego, CA-based company was founded in 2000 and has yet to generate revenue. Celladon Corporation initially filed confidentially on 9/6/2013. J.P. Morgan and Barclays were set to be the joint bookrunners on the deal.