Flexion Therapeutics and Xenon Pharmaceuticals Announce Flexion’s Acquisition of an Investigational NaV1.7 Inhibitor for the Treatment of Post-Operative Pain

Tuesday, September 10, 2019

Flexion Therapeutics, Inc. and Xenon Pharmaceuticals Inc. today announced that the companies have entered into a definitive agreement that provides Flexion with the global rights to develop and commercialize XEN402, a NaV1.7 inhibitor, for the management of post-operative pain.

Flexion’s new preclinical program, known as FX301, will consist of XEN402 formulated for extended release from a thermosensitive hydrogel. The initial development of FX301 is intended to support administration as a peripheral nerve block for control of post-operative pain. Within minutes following injection, the thermosensitive formulation has been shown to transition from a liquid to a gel, an effect that provides local delivery of XEN402 near target nerves for up to a week. Unlike typical local anesthetics, the selective pharmacology of XEN402 has the potential to provide effective pain relief while preserving motor function. As such, FX301 is expected to enable ambulation, rapid discharge, and early rehabilitation following musculoskeletal surgery.

Under the terms of the agreement, Flexion acquired the global rights to the XEN402 program including a broad patent estate as well as the associated non-clinical, clinical and manufacturing components. As consideration for the acquisition, Flexion paid Xenon an upfront payment of $3 million. In addition, Xenon will also be eligible for various CMC, development and regulatory milestone payments of up to $9 million through initiation of a Phase 2 proof of concept (PoC) clinical trial. Following successful PoC, Xenon may be entitled to future clinical development and global regulatory approval milestone payments of up to $40.75 million, commercialization milestone payments of up to $75 million, as well as future sales royalties ranging from mid-single to low-double digit percentages. As part of the agreement, Flexion will assume Xenon’s obligation to pay a low single-digit percentage of sales royalty to Teva Pharmaceuticals International GmbH. Flexion anticipates initiating FX301 clinical trials in 2021.

Commenting on the deal Michael Clayman, M.D., President and Chief Executive Officer of Flexion said, “FX301 is a natural fit for Flexion as it leverages our deep understanding of musculoskeletal pain and our demonstrated formulation expertise. Post-operative opioid use is considered a key cause of subsequent opioid use disorder, particularly following musculoskeletal surgery. We believe FX301 may directly address a substantial medical challenge by potentially providing durable and meaningful post-operative pain relief, while sparing motor function. Importantly, Xenon has amassed an extensive amount of pre-clinical data from in vivo pain models, and XEN402 has been previously tested in multiple human clinical trials, which we believe can accelerate our development efforts to move FX301 into the clinic.”

Dr. Simon Pimstone, Xenon’s Chief Executive Officer added, “We believe that FX301 holds great potential as a local therapy for post-operative pain based on in vivo data with XEN402 that demonstrated good efficacy when delivering this drug to the target site at high concentration. Thus, we believe that locally administered, long acting delivery of XEN402 may represent a promising new way to address post-operative pain. With their experience developing and commercializing novel and locally acting therapies, we are excited that Flexion is committed to advancing XEN402 in their proprietary formulation as FX301. We look forward to the progression of FX301 as it advances through clinical development.”