Gastrointestinal and autoimmune company Arena Pharmaceuticals announced mixed topline results for the Phase IIb trial of its oral cannabinoid receptor type 2 (CB2) agonist olorinab.
Gastrointestinal and autoimmune company Arena Pharmaceuticals announced mixed topline results for the Phase IIb trial of its oral cannabinoid receptor type 2 (CB2) agonist olorinab, including a miss on its primary endpoint of reducing overall abdominal pain in irritable bowel syndrome (IBS) patients. After the announcement, the company’s stock fell almost 9% to $69.74 this morning.
Abdominal pain was measured using the Average Abdominal Pain Score (AAPS), and Arena was looking for improvements in IBS patients with predominant constipation or diarrhea, with a baseline score of 6.5 or higher indicating moderate to severe pain–seen in about half of the study’s 273 participants. Orlinab was given at three doses in the study, three times per day each.
At the highest, 50 mg dose, the drug candidate did meet statistical significance, reducing AAPS by 1.64 points compared to placebo, and 3.93 points overall from baseline, at week 12. Consistent with an earlier Phase I trial, olorinab was safe and well tolerated.
Almost 80% of IBS patients suffer from recurring or continuous abdominal pain.
This was the first Phase II study of a CB2 agonist in IBS pain, says Paul Streck, Senior Vice President for Clinical Development and Chief Medical Officer at Utah-based Arena. “As a Phase 2 trial we were evaluating safety in this population as well as looking for an initial signal of efficacy. We are encouraged by the signal.”
The company has not announced orlinab, will be studied in other diseases, but CB2 is known to regulate inflammation, and is being targeted by other companies. Corbus Pharmaceuticals has its oral CB2 agonist lenabasum in a Phase III study for dermatomyositis, and Phase II studies in systemic lupus erythematosus.
Last year, Corbus Pharmaceuticals announced lenabasum failed to meet its primary endpoint in a separate Phase III trial for diffuse cutaneous systemic sclerosis, a rare autoimmune disease. In other trials, it showed evidence of reducing inflammation and fibrosis.
In addition, Centrexion Therapeutics is currently testing its CB2 agonist, CNTX-6016, in a in Phase Ib/IIa study for diabetic neuropathy.
Arena’s lead program is etrasimod, a modulator of another immune target, sphingosine 1-phosphate (S1P) receptor. Etrasimod is in two Phase III trials for ulcerative colitis, and last month Arena launched a Phase II trial in patients with eosinophilic esophagitis, a rare autoimmune-driven digestive disease. On the back of Phase 2b data, the company is also planning a Phase III trial for etrasimod in atopic dermatitis.
