Results support advancement of the novel, oral drug candidate to the next stage of development

SAN DIEGO, CA, USA I April 29, 2015 I Arena Pharmaceuticals, Inc. (NASDAQ: ARNA) today announced favorable results from a Phase 1 single-ascending dose clinical trial of APD371, a highly selective and potent agonist of the cannabinoid 2 (CB2) receptor currently in development for the treatment of pain and potentially fibrotic diseases.

The randomized, double-blind and placebo-controlled Phase 1 clinical trial enrolled 56 healthy adults to evaluate the safety, tolerability and pharmacokinetics of single-ascending doses of APD371. Dose responsive exposure was observed over the explored dose range of 10-400 mg with good tolerability at all doses administered.

“In this trial, APD371 was well tolerated, as evidenced by the lack of dose-limiting adverse events, at drug levels greatly exceeding those anticipated as needed for activating the CB2 receptor,” said William R. Shanahan, Jr., M.D., Arena’s Senior Vice President and Chief Medical Officer. “We believe that the intrinsic properties of this compound could offer advantages over currently marketed treatments for pain.”

About APD371

APD371, an orally available agonist of the CB2 receptor, is Arena’s internally discovered investigational drug candidate for several potential indications, including pain and fibrotic diseases. This compound, through its high level of observed selectivity for the CB2 receptor versus the CB1 receptor, is designed to provide pain relief without psychotropic effects or the potential for dependence or abuse. Preclinical efficacy with APD371 has been shown in animal models of osteoarthritic and neuropathic pain.

About Arena Pharmaceuticals

Arena is embracing the challenge of improving health by seeking to bring innovative medicines targeting G protein-coupled receptors to patients. Arena’s focus is discovering, developing and commercializing drugs to address unmet medical needs, and BELVIQ® (lorcaserin HCl) is Arena’s first internally discovered drug approved for marketing. Arena’s US operations are located in San Diego, California, and its operations outside of the United States, including its commercial manufacturing facility, are located in Zofingen, Switzerland. For more information, visit Arena’s website at www.arenapharm.com.

SOURCE: Arena Pharmaceuticals