Pfizer buys Amplyx to grow infectious disease pipeline

Pfizer sign
Fosmanogepix's mechanism is distinct from those of the three existing antifungal classes. (Tracy Staton)

Pfizer has bought infectious disease biotech Amplyx Pharmaceuticals for an undisclosed sum. The deal gives Pfizer control of a pipeline led by phase 2 antifungal candidate fosmanogepix.

Amplyx received investment from Pfizer last year as part of a $93 million series C round that set the biotech up to advance fosmanogepix and MAU868, a neutralizing antibody targeting the BK virus. In the months after disclosing the investment, Amplyx shared phase 2 data linking fosmanogepix to an 80% treatment success rate in patients with invasive fungal infections caused by Candida.

The progress has persuaded Pfizer to acquire Amplyx outright. In return for an undisclosed financial package, Pfizer has added fosmanogepix, MAU868 and the early-stage antifungal APX2039 to its R&D pipeline.

Pfizer focused on fosmanogepix, Amplyx’s lead compound, in its statement to disclose the takeover. Fosmanogepix is a prodrug of manogepix, an inhibitor of the fungal enzyme Gwt1. Eisai discovered manogepix by searching for small molecules that disrupt the assembly of mannoproteins into fungi  cell wall glucan. The mechanism is distinct from those of the three existing antifungal classes.   

If validated in the clinic, the novel approach could enable physicians to treat troublesome stains such as echinocandin-resistant Candida and azole-resistant Aspergillus. Amplyx has studied intravenous and oral forms of fosmanogepix, raising the prospect of patients receiving the antifungal agent into their veins while in hospital before taking it by mouth once they return home.

Pfizer framed the acquisition as part of its continuous search for opportunities to build its portfolio of anti-infective therapies. The focus on growing the anti-infective portfolio dates back years, with the 2016 takeover of AstraZeneca’s small-molecule antibiotics business and the 2017 in-licensing of the European rights to Basilea’s antifungal Cresemba distant examples of the strategy in action.

Last year, Pfizer’s hospital business, which sells infectious disease products, grew U.S. sales by 9%, in part due to the introductions of anti-infectives. Pfizer’s top-selling antifungal is Vfend, which pulled in revenues of $270 million in the pandemic-affected 2020, down from $346 million the year before. None of the anti-infectives are blockbusters, but, collectively, they are a big part of Pfizer’s $8 billion hospital business.