GlaxoSmithKline has entered into an alliance with antibiotics specialist Mpex Pharmaceuticals in a deal that could net the San Diego-based privately-held firm well over $1 billion.

The two firms said they will be working on the discovery, development and commercialisation of novel medicines for bacterial diseases. The collaboration gives GSK access to Mpex's efflux pump inhibitors and related technology for use in combination with a variety of the UK drug major’s antibiotics, including “existing commercial” treatments, as well as investigational compounds.

Under the terms of the agreement, GSK will get rights to product candidates that are directed to “three different target product profiles and with the potential to deliver up to seven treatment options”. Mpex will receive an $8.5 million upfront payment and a $6.5 million equity financing commitment from GSK and will also be eligible to receive development, regulatory and commercial milestones ranging up to $200-$250 million for each drug. If GlaxoSmithKline exercises its option on a particular treatment, Mpex will receive tiered royalties.

Daniel Burgess, Mpex chief executive, said that to date, “safe and effective EPIs have not been developed” but the pact with GSK “will maximise our chances of success to develop a portfolio of products from this platform technology that is greater than we could hope to develop on our own”. Zhi Hong, senior vice president of GSK’s Infectious Diseases Center of Excellence for Drug Discovery, noted that only two new classes of antibiotics have been discovered over the last three decades, so “paradigm-shifting approaches are needed” to address the problems of bacterial infections and drug resistance.

Bacterial efflux pumps are an intrinsic defence mechanism in gram-negative bacteria that expel toxins such as antibiotics that have permeated the outer cell membrane before they can reach their targets and kill the bacteria, GSK noted. There are currently no drugs approved to inhibit the activity of these efflux pumps and restore the potency of otherwise effective antibiotics.