Sanofi antibiotics partner Rib-X aims for $80M IPO

Antibiotics developer Rib-X Pharmaceuticals wants to go public after burning through more than $238 million since 2000. The New Haven, CT-based company hasn't said how many shares it plans to sell in the hoped-for initial public offering, but the proposed IPO sum is $80 million, according to an SEC document.

The developer (a 2011 Fierce 15 company) has arrived with its plans to go public carrying a partnership with Sanofi ($SNY), a lead drug that is slated to enter late-stage trials next year, and no products on the market. Delafloxacin, the company's most advanced drug, is in a Phase IIb clinical study as a first line of attack against skin infections, and the drug could be useful to treat infections caused by MRSA bugs. To combat the most difficult-to-treat infections, the developer has been focusing on drugs that home in on binding sites in bacterial ribosomes. Sanofi inked a deal with Rib-X for a preclinical drug that works like this called RX-04, bringing Rib-X a $10 million upfront payment and $9 million in near-term research funding.

Rib-X's bid to go public comes after some interesting biotech IPO activity this month. Clovis Oncology wrapped up a $130 million IPO before Thanksgiving, garnering the lower end of its projected share price for the public debut, and cancer drug developer NewLink Genetics finished a smaller $43.4 million initial public offering, settling for a lower share price than it had previously sought. Cambridge, MA-based Verastem is testing the IPO waters with plans to develop drugs that target cancer stem cells, even though the company's research hasn't advanced beyond the preclinical phase.

Rib-X steps up to the plate with an antibiotics pipeline. While there's been a call for new antibiotics to fight drug-resistant bugs, Big Pharma has generally kept its distance from the field because of market challenges. For one thing, antibiotics are only taken temporarily, while patients with chronic diseases could take drugs for their illnesses for their entire life. Rib-X bucked the Big Pharma trend to an extent with its Sanofi deal, and its CEO Mark Leuchtenberger led his last antibiotics company Targanta Therapeutics to an IPO.

Rib-X has already won over a lineup of private equity investors, raising $208.4 million from backers such as Warburg Pincus, Saints Capital, GSK's SR One, Medimmune Ventures and Oxford Bioscience Partners. The company had cash and cash equivalents of $9.7 million as of Sept. 30, according to its SEC filing.

- here's the company's release
- read the SEC filing
- and Xconomy's coverage

Special Report: Rib-X Pharmaceuticals - 2011 Fierce 15