Formerly known as PhageTech, Targanta moved its headquarters to Cambridge from Montreal last year. At about the same time, it brought on a new CEO, Mark Leuchtenberger, whose previous Boston-area company, Therion Biologics, cratered a year ago when its cancer vaccine for melanoma failed. Therion’s former CFO, George Eldridge, assumed the same job at Targanta in February.

The company’s lead drug candidate, oritavancin, is an intravenous antibiotic intended for treatment of drug-resistant bacterial infections. It has been tested against skin and “skin structure” infections as well as bacteremia, an infection of the blood, and is intended to supplant vancomycin, a generic antibiotic that is starting to lose potency against resistant bacterial strains.

Targanta’s S-1, however, makes for some interesting reading. Oritavancin was originally developed by Lilly, which subsequently licensed it to InterMune. Targanta acquired the rights to the drug in late 2005. Its two late-stage “phase III” tests in skin and skin-structure infections were conducted by Lilly and InterMune, despite which Targanta doesn’t envision filing for FDA approval until the beginning of next year.

Oritavancin also faces the prospect of serious competition from existing antibiotics, including vancomycin, Cubist Pharmaceuticals‘ Cubicin (daptomycin), and Pfizer‘s Zyvox (linezolid). More potential rivals are on their way — the S-1 names Pfizer’s Zeven (dalbavancin), Theravance’s telavancin, Johnson & Johnson’s ceftobiprole and iclaprim from Arpida. Sounds like things could be pretty crowded by the time oritavancin makes it through the FDA.

This is all straight from the “Risk Factors” section of the S-1, where companies routinely exaggerate any conceivable risk to their future business, so you may want to take it with a grain of salt. The company’s venture backers — in February, it raised a $70 million third round — certainly appear to have done so. Still, it’s unusual to see a company file for an IPO in a soft market for biotech offerings with an in-licensed pipeline and so many real and potential competitors hanging around. We’ll see if investors are willing to overlook this stuff, although I suspect this offering might make them just a little nervous.