Axsome picks up Pfizer's phase 3 fibromyalgia castoff 

People shaking hands across a desk that has computer and papers on it
Pfizer offloaded esreboxetine to Axsome as part of a broader deal. (rawpixel/Pixabay)

Axsome Therapeutics has licensed a fibromyalgia candidate more than a decade after Pfizer dropped it in light of clinical data. The deal gives Axsome the chance to resurrect a drug that beat placebo in phase 3 but nonetheless fell by the wayside at Pfizer.

Pfizer revealed it was stopping development of its fibromyalgia prospect, selective norepinephrine reuptake inhibitor esreboxetine, early in 2009 “to allocate additional resources to higher-potential development programs.” Several years later, researchers published phase 3 data linking esreboxetine to reductions in pain and improved scores on a fibromyalgia questionnaire.

Despite the phase 3 hitting its primary endpoint, neither Pfizer nor any other company sought to take esreboxetine forward in fibromyalgia. Now, that is set to change. 

Axsome has picked up the exclusive right to develop and commercialize esreboxetine, now known as AXS-14, in the U.S. in fibromyalgia and other indications. The deal gives Axsome access to the results Pfizer generated during its aborted attempt to bring esreboxetine to market.

Pfizer offloaded esreboxetine to Axsome as part of a broader deal covering data on reboxetine, an old depression drug used outside of the U.S. Reboxetine never won full U.S. approval in depression, but Axsome spied a new opportunity for the molecule in narcolepsy in 2018, leading to midphase data suggesting the norepinephrine reuptake inhibitor can cut the frequency of cataplexy attacks. 

With Axsome planning to start a phase 3 trial of reboxetine, now renamed AXS-12, later this year, the company has turned to Pfizer to streamline its path to market. Axsome thinks the reboxetine data it licensed from Pfizer will enable it to skip or shrink certain studies of AXS-12.

Pfizer has handed over the reboxetine data and rights to esreboxetine in return for $3 million in cash and $8 million worth of Axsome stock. If Axsome’s R&D programs succeed, Pfizer could pocket up to $323 million more in regulatory and sales milestones. The agreement also gives Pfizer a right of first negotiation on any future transactions involving AXS-12 or AXS-14.