Arena’s etrasimod meets primary and secondary endpoints in ulcerative colitis trial

Patients receiving the 2 mg dose of etrasimod achieved statistically significant improvements versus placebo in the primary, all secondary, and clinical remission endpoints. 

Relative to placebo, there was a statistically significant (p = 0.009) 0.99 point improvement in a 3-component (stool frequency, rectal bleeding and findings on endoscopy) Mayo Clinic Score (ranging from 0 to 9) with etrasimod 2 mg at week 12. 

In the 1 mg group, there was a 0.43 point improvement in 3-component Mayo Clinic Score at week 12 relative to placebo, which was not statistically significant (p = 0.146). Significantly more patients in the etrasimod 2 mg group achieved endoscopic improvement compared with placebo (41.8% vs. 17.8%, p = 0.003).

The proportion of patients achieving clinical remission, defined by the 3-component Mayo Clinic Score, was 33.0% in the etrasimod 2 mg group compared to 8.1% for the placebo group (p < 0.001). Remission as defined by the 4-component Total Mayo Clinic Score was 24.5% and 6.0% for etrasimod 2 mg and placebo, respectively (p = 0.004).

Etrasimod was well tolerated and there were fewer patients with serious adverse events (SAEs) compared to placebo (0% in 2 mg, 5.8% in 1 mg and 11.1% in placebo). Impact on heart rate and atrioventricular (AV) conduction was low throughout the study with no discontinuations from study related to bradycardia or AV block. There were no increases in liver function tests compared to placebo and no reports of macular edema or pulmonary function test abnormalities.  The Company plans to present full study results at future medical congresses.

Arena Pharmaceuticals research and development executive vice president  and chief medical officer Dr Preston Klassen said: "We believe these data support proceeding to a Phase 3 program in ulcerative colitis and continuing efforts to understand the broad potential utility of etrasimod in other immune and inflammatory diseases with significant unmet needs.

“Along with the positive Phase 2 results for ralinepag reported last year, this important milestone for the Company further amplifies our conviction in Arena's internally discovered and developed compounds and their potential to be best-in-class."

OASIS was a randomized, double-blind, placebo-controlled, parallel-group, dose-ranging study to assess safety and efficacy of two orally administered doses (1 mg and 2 mg) of etrasimod in patients with ulcerative colitis (UC) across 71 sites in 16 countries.

The OASIS trial randomized 156 patients, with moderate to severe UC (3-component Mayo Clinic Score of 4-9 with an endoscopic subscore ≥ 2 and a rectal bleeding score ≥ 1).  The pre-specified statistical analysis plan applied one-sided testing, in which conventional statistical significance is achieved at p-values < 0.025.

Etrasimod (APD334), is an oral, once-daily, next generation, selective sphingosine 1-phosphate (S1P) receptor modulator, discovered by Arena, designed to provide systemic and local cell modulation by targeting S1P receptor subtypes 1, 4 and 5, while avoiding subtypes 2 and 3.