UPDATED: PTC, Esperion, bluebird join the IPO frenzy in biotech with genetic therapies

At least three more biotech outfits emerged this week as contenders to complete initial public offerings, highlighting the open season for the deals this year. Bluebird bio and PTC Therapeutics have mounted campaigns to go public with pipelines that target the molecular causes of rare genetic diseases.

PTC Therapeutics, which withdrew a previous IPO plan in April 2007, aims to raise up to $85 million as the South Plainfield, NJ-based biotech develops its lead drug ataluren for genetic disorders with nonsense mutation. The company has launched a Phase III study of the small molecule in patients with nonsense mutation Duchenne muscular dystrophy, which is a disease that causes muscle wasting in young boys and leads to premature death. Its second most advanced use of the drug is for cystic fibrosis, an inherited lung disorder for which the company aims to begin a confirmatory Phase III study in the second half of this year.

Both DMD and CF are hot areas of drug development. PTC has had mixed results in advancing ataluren, which was the key asset in a major collaboration with Genzyme in DMD. Genzyme abandoned the pact after weighing midstage trial data. Last year the company sought conditional approval of the drug for nmDMD in Europe, and this year the company has learned of objections from regulators and noted the potential for the company to lose its bid for conditional approval in an SEC filing.

The company, which wants to list its shares on the Nasdaq under the symbol "PTCT," had burned through $291.9 million as of March 31, at which point the company reported having $50.2 million in cash and equivalents.

Cambridge, MA-based bluebird bio publicly revealed plans for an $86.25 million IPO earlier this week. The company has been one of the groups to bring gene therapy back from the grave in the biotech industry, nailing down a collaboration with biopharma powerhouse Celgene ($CELG) this year in oncology and plans to develop lead products for childhood cerebral adrenoleukodystrophy and rare hereditary blood disorders.

As of the end of March, bluebird had cash and equivalents of $131.8 million and an accumulated deficit of $79.9 million. Third Rock Ventures, which is bluebird's largest shareholder with a 28% ownership stake, has raised more than $1.3 billion for three biotech funds over the past 6 years and bluebird could become the first one of its portfolio companies to go public.

UPDATE: Esperion Therapeutics wants to go public too. This week the Plymouth, MI-based drug developer filed for a maiden public offering to raise up to $70 million. The company comes to the table with a cholesterol-lowering drug called ETC-1002, which has completed early midstage trials. This is the new Esperion. Pfizer acquired the old Esperion in 2004. Afterward, entrepreneurs formed Esperion and grabbed rights to ETC-1002 from Pfizer, which had acquired the compound in the buyout of the original Esperion. 

The company has raised $57 million to develop the drug, which could attract some serious interest because of the size of the market for treating high cholesterol. It aims to list its shares on the Nasdaq under the symbol "ESPR." S-1

- check out bluebird's S-1 filing
- and PTC's filing

Special Reports: Bluebird Bio – 2012 Fierce 15 | Top 10 biotech IPOs of 2012