Arena Pharma’s cannabinoid receptor-targeting olorinab could help treat the pain associated with Crohn’s disease, one of the most debilitating symptoms of the inflammatory bowel disorder.

Olorinab—a cannabinoid receptor type 2 (CB2) agonist—was able to reduce abdominal pain scores by at least 30% compared to baseline levels in 11 evaluable patients in the phase 2a study, which recruited 14 subjects with mild Crohn’s. Shares in the biotech rose almost 3% in after-hours trading after the results were announced.

The drug achieved an average 4.6-point improvement on the 10-point AAPS pain scale, which meets the company’s objective of exceeding a two-point improvement which might be observed with placebo.

Arena says the pain relief kicked in rapidly, lasted throughout the eight-week study and was seen with both doses tested: 25 mg and 100 mg given three times a day. Olorinab was also well-tolerated with no patients discontinuing because of side effects.

While acknowledging that the trial was small and uncontrolled, the San Diego-based biotech is sufficiently encouraged to plan a larger trial of olorinab in "several diseases in which gastrointestinal pain is a hallmark," says Preston Klassen, M.D., Arena’s chief medical officer. There’ll be more information about its plans at the company’s R&D update early next month, he adds.

Abdominal pain is a big problem in IBD, particularly as recent animal studies have suggested that opioid painkillers may aggravate symptoms because they have deleterious effects on the GI system. Meanwhile, there’s some evidence that cannabis itself can be used to alleviate diarrhea, abdominal pain, and loss of appetite in IBD.

Olorinab is the third in a trio of new drugs that Arena is bringing through clinical development in-house, alongside late-stage IP receptor agonist ralinepag for pulmonary arterial hypertension—which aced a phase 2 trial last year—and etrasimod, an S1P receptor modulator for ulcerative colitis, Crohn’s and primary biliary cholangitis which is also heading for phase 3 after a positive midstage trial.

Analysts at Cantor Fitzgerald have described olorinab as an "underappreciated asset" in Arena’s pipeline with a profile that could position it favorably against other cannabinoid receptor modulators and say the new data "clearly establish olorinab as a viable drug worthy of advanced development."

Just what the target indication in later-stage development will be isn’t clear just yet, as the company has suggested it may go after Crohn’s or irritable bowel syndrome, which would be a larger target population.

Either way, having positive data on three drugs continues Arena’s bounce-back from a difficult 2016, which saw it shed almost three-quarters of its staff before selling global rights to its struggling obesity product Belviq (lorcaserin) to partner Eisai and refocusing on its pipeline.

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