Mpex Pharmaceuticals Inc., which develops bacterial resistance inhibitors in combination with existing antibiotics to treat infections, raised $32 million in its Series B round.

"This financing was, we hope, sufficient to advance the first two products into or through early clinical development," said Bill Gerhart, president and CEO of the San Diego-based company, "as well as provide us with the infrastructure and organizational credibility to attract and obtain additional partnerships for our other programs."

The round was led by Boston-based SV Life Sciences, along with HBM BioVentures Ltd. and HBM BioCapital LPs, both part of Baar, Switzerland-based HBM BioVentures. Other new investors are San Francisco-based Aberdare Ventures and Chicago-based Adams Street Partners, plus existing investors San Diego-based Western States Investment Group and Clifton Park, N.Y.-based Charitable Leadership Foundation. Mpex has raised about $35.7 million to date.

The company's work is based on a technology platform that combines small-molecule inhibitors of bacterial resistance with an antibiotic to address the growing problem of antibiotic resistance. Its first candidate, an aerosol product being evaluated in small pilot and exploratory Phase Ib studies, is a drug and device combination to treat respiratory infections. Mpex has not released the specific components of the product, though results of these early studies will determine whether the company advances into Phase II trials or re-optimizes the combination for another Phase Ib study.

Gerhart said the product initially is being developed for patients with cystic fibrosis, a disease that causes mucus to accumulate in the lungs, providing a host for bacterial infections that eventually could lead to decreased lung function and death.

"So what we hope to do with our antibacterial is to provide a superior option to reduce the pulmonary exacerbations and improve lung function," he said.

The company's second product is an intravenously administered drug aimed at treating infections in hospital settings, where "the bacteria that survive are the toughest of the tough," Gerhart said, specifically Pseudomonas aeruginosa, the "dominant respiratory pathogen in hospitals that contributes to patient morbidity and mortality."

Mpex's latest financing is expected to get it through the end of Phase II studies with the aerosol product and advance the IV drug into human trials, Gerhart said, adding that funds would power operations for about two and a half to three years.

When it comes to potential partnerships, Gerhart said, "our strategy is to raise enough capital to get at least these first two programs to Phase II. We have a third program that we'll seek to partner earlier simply because it's for a very large market."

That program focuses on community-acquired infections and "would require a much larger investment," he added.

Though the combination of bacterial resistance inhibitors and antibiotics are not new to the industry - Augmentin (amoxicillin and clavulanate potassium) by London-based GlaxoSmithKline plc is approved for the treatment of bacterial sinusitis and community-acquired pneumonia - Mpex has introduced a different mechanism of action. The company's products target efflux pumps, proteins that are found in bacterial membranes to pump out antibiotics and other substances toxic to bacteria, resulting in a reduced drug concentration. By inhibiting the efflux pump, the antibiotic is able to maintain its potency in the bacterial cell.

To put it simply, "we're shutting down a resistance mechanism that bacteria use to defend themselves," Gerhart said.

Because companies like GSK already have helped establish a precedent for this type of combination product, Mpex has some guidance as far as development. That, Gerhart said, in addition to working with existing antibiotics has mitigated some of the commercial risk for the company, which might make it an attractive partner for large pharma.

"If you have an antibiotic that's coming off patent," he said, "and you have the ability to make it better and extend it for another 20 years, I think that's a pretty compelling opportunity."