Arena Pharmaceuticals, Inc. (Nasdaq: ARNA) and Aristea Therapeutics, Inc. today announced a strategic collaboration to advance the clinical development of RIST4721, an oral CXCR2 antagonist being developed by Aristea for the treatment of palmoplantar pustulosis (PPP) and other neutrophil-mediated diseases.

Under the terms of the agreement, Arena will provide a $60 million upfront payment to Aristea and a $10 million equity investment in Aristea's Series B financing. In return, Aristea has granted Arena an exclusive option to acquire Aristea, including rights to all CXCR2 programs, upon completion of the Phase 2b study of RIST4721 in PPP. The agreement also provides a framework during the option period for the companies to jointly explore the development of additional neutrophil-mediated diseases, including hidradenitis suppurativa (HS) and inflammatory bowel disease (IBD), potentially generating multiple data readouts during the option period.

Separately, Aristea announced today the closing of a $63 million Series B financing led by Fidelity Management & Research Company, LLC, with participation by existing investor Novo Holdings A/S and new investors Arena Pharmaceuticals and funds managed by Tekla Capital Management, LLC.

"The collaboration and option agreement with Aristea provides Arena with an opportunity to bolster our early- to mid-stage immunology pipeline in two of our core therapeutic areas, dermatology and gastroenterology," said Amit D. Munshi, President and Chief Executive Officer of Arena Pharmaceuticals. "We look forward to working closely with the Aristea team with the goal of bringing a novel therapy to patients with neutrophilic diseases."

"This collaboration reflects Arena's commitment to Aristea's highly innovative science, the significant progress we have made in exploring best-in-class therapeutics for serious and rare inflammatory diseases, and the value of our clinical pipeline," said James M. Mackay, Ph.D., Chief Executive Officer of Aristea Therapeutics. "There are currently no approved therapies for PPP in U.S. or EU. Our lead candidate product, RIST4721, has completed a Phase 2a study and it is on track to initiate Phase 2b. We look forward to our productive collaboration with Arena and to accelerating the development of RIST4721 to bring this therapy to patients."

About RIST4721 and Palmoplantar Pustulosis (PPP) 

RIST4721 is an oral CXCR2 antagonist being developed for the treatment of PPP with results reported from its Phase 2a clinical trial in 2020. PPP is a debilitating condition that is characterized by repeated flares of sterile neutrophil-filled pustules that lead to redness and thickening on the palms of the hands and/or the soles of the feet and associated pain, itching and burning sensations. CXCR2 plays important roles in neutrophil recruitment to inflammatory sites and represents a promising therapeutic target for the treatment of neutrophil-mediated inflammatory diseases. Later this year, Aristea is initiating a Phase 2b study to investigate RIST4721 in PPP and plans to expand development into two additional orphan indications, familial Mediterranean fever (FMF) and Behcet's disease.

About Arena Pharmaceuticals

ARENA Pharmaceuticals is a team with a singular purpose - deliver important medicines to patients. In a rapidly changing global market, we work with a sense of urgency every day to understand the needs of all our stakeholders, identify bold, sometimes disruptive, ideas to get medicines to patients, and relentlessly execute until it's done.

We are developing a richly diversified portfolio of therapeutic candidates targeting gastroenterology, dermatology and cardiology. Our pipeline includes four investigational medicines in eight indications and eleven ongoing or planned clinical trials. To fuel our growth, we are unlocking the value of our historical GPCR research with a sustainable discovery engine for broad portfolio expansion.

Arena's lead investigational compound in dermatology, etrasimod, is a highly selective, once-daily, oral sphingosine 1-phosphate (S1P) receptor modulator intended to provide systemic and local effects on specific immune cell types with the potential to treat multiple immune-mediated inflammatory diseases, including ulcerative colitis, Crohn's disease, eosinophilic esophagitis, atopic dermatitis, and alopecia areata.

About Aristea Therapeutics

Aristea Therapeutics (Air-iss-tay-uh) is a clinical-stage immunology focused drug development company developing novel therapies to treat serious inflammatory orphan diseases. The Aristea team is leveraging its broad industry expertise and proven success in drug development to form synergistic partnerships and build a pipeline of novel drugs. Aristea's lead program, RIST4721, is currently in Phase 2 clinical development. Aristea is headquartered in San Diego, CA.