Roche has ended a two-year-old collaboration with Polyphor to develop and commercialize its macrocycle antibiotic candidate POL7080, designed to fight bacterial infections linked to the multidrug-resistant Pseudomonas species.

The collaboration could have generated Polyphor up to CHF 500 million ($485.7 million), equivalent to $547.4 million when the collaboration was launched in November 2013, including the CHF 35 million ($34 million) that Roche agreed to pay Polyphor upfront.

The collaboration marked Roche’s return to antibiotics development after ending a previous collaboration more than a decade earlier.

Roche first confirmed to the Swiss newspaper NZZ am Sonntag that it will return POL7080—which Roche has labeled RG7929—to Polyphor.

“The decision to discontinue our involvement in the clinical development of RG7929/POL7080 is based on our assessment of the current status and anticipated progress of the RG7929/POL7080 development program,” Roche said in a statement emailed to GEN.

POL7080 was the first of a new class of antibiotics derived from Polyphor’s protein epitope mimetics (PEM) technology platform, designed to discover and optimize drug candidates that interfere with targets difficult to modulate with classic small molecule approaches. PEM are medium-sized (0.7-2 kDa), fully synthetic cyclic peptide-like molecules designed to mimic the two most relevant secondary structure motifs involved in protein-protein interactions (PPIs): the β-hairpin and the α-helix.

According to an update posted November 24 on ClinicalTrials.gov, Polyphor alone was recruiting participants for a Phase II trial of POL7080 designed to assess the compound’s pharmacokinetics, safety, and efficacy in patients with ventilator associated Pseudomonas aeruginosa pneumonia. The study has an estimated patient enrollment of 25, and an estimated completion date of May 2016.

In a statement emailed to GEN, Polyphor cited a July announcement that Roche would end its participation in clinical development of POL7080 by the end of this year.

“Polyphor is continuing, as planned, its ongoing open-label phase II PK study in ventilator-associated pneumonia (VAP) with confirmed Pseudomonas aeruginosa,” the company said in a statement emailed to GEN. “In parallel, we are  preparing for having discussions with regulatory authorities in the course of next year on the design and further details of a subsequent pivotal trial.”

POL7080 is in Phase II testing for Pseudomonas infections, while a broad-spectrum program involving the compound is in the in vivo discovery phase, Polyphor stated on its website.

Roche acknowledged that drug-resistant infections have created an urgent demand for new treatments: “Roche focuses on novel targets for both pathogen-specific and broad-spectrum antibiotics that deliver enhanced activity against difficult-to-treat pathogens and difficult-to-treat sites of infection.  We concentrate on areas where no treatment options currently exist to treat serious, multidrug resistant strains.”

The company cited its RG6080 (OP0595), a Phase I beta-lactamase inhibitor (BLI) being developed through an up-to-$750 million collaboration launched in January with Meiji Seika Pharma and Fedora Pharmaceuticals. Roche stated that a Phase I clinical trial successfully demonstrated the clinical safety and tolerability of RG6080. Roche will assume full responsibility for further development and commercialization, excluding Japan, where Meiji retains development rights.

Roche also cited two antibiotics partnerships launched last year. The pharma giant has licensed for up to $191 million-plus Discuva’s Selective Antibiotic Target IdentificatioN (SATIN) technology platform to discover and develop new antibiotics for life-threatening infections caused by multidrug resistant Gram-negative bacteria. Also, Roche agreed to provide an undisclosed amount of nondilutive R&D funding to Spero Therapeutics, in return for an option to acquire Spero’s lead program at the IND application phase.

[This report has been updated from an earlier edition to include statements emailed to GEN by Roche and Polyphor].