Ardelyx Completes ACCEL Enrollment Ahead of Schedule, Targets Preliminary Data in 2027
Key Facts
Ardelyx said on November 3, 2026, that it had completed enrollment in the Phase 3 ACCEL trial ahead of schedule, with preliminary data expected in the second half of 2027. Chief Executive Michael Raab said completing enrollment ahead of schedule "represents an important milestone for the company." The study is testing tenapanor, marketed as IBSRELA, in adults with chronic idiopathic constipation. Completion of enrollment marks operational progress in a clinical program whose results are not yet available. If the trial succeeds, the company plans to submit a supplemental drug application to the U.S. Food and Drug Administration for this indication.
The indication being tested in ACCEL differs from IBSRELA’s current U.S. approval, which is limited to treating irritable bowel syndrome with constipation in adults. The drug is not yet approved to treat chronic idiopathic constipation, so completion of enrollment does not mean it has received a new approval. Ardelyx estimated that more than 34 million Americans have the condition, putting the size of the target population at the heart of efforts to expand the drug’s use. Any regulatory application depends on the trial’s results, as the company explained in its filing. The expected data therefore remain a milestone for assessing efficacy before moving to an approval application.
The company designed ACCEL as a multicenter, randomized, double-blind, placebo-controlled trial to assess the safety and efficacy of tenapanor. Participants receive treatment twice daily for 26 consecutive weeks. The primary endpoint will measure patient-reported outcomes for constipation, with a focus on sustained efficacy in relieving it. The design allows outcomes for participants receiving the drug to be compared with those receiving placebo over the specified treatment period. The enrollment completion announcement did not include results on the drug’s performance or participants’ response.
Ardelyx announced in January 2026 that the first participant had been dosed, saying at the time that enrollment would continue through the year and preliminary data were expected in the second half of 2027. Enrollment was subsequently completed ahead of the target, while the announced timeline for data remained unchanged. The current progress places the trial between its start and the preliminary data readout, without providing evidence of a clinical result. The company said physicians’ interest and the pace of enrollment "confirm treating physicians’ enthusiasm for a new option." The quote reflects the company’s view of interest in the study, not a judgment on the treatment’s efficacy.
ACCEL is part of an effort to expand the clinical use of a drug that already generates sales for another condition. In the second quarter of 2026, IBSRELA recorded revenue of $86.2 million, up 33% year over year. Ardelyx said quarterly revenue came in below its expectations because of increased drug utilization management procedures by payers. On August 6, the company lowered its 2026 IBSRELA revenue guidance to a range of $350 million to $370 million, also linking the change to an increase in those procedures. These figures show that progress in studying a new use is taking place alongside commercial challenges in the current market.
IBSRELA revenue was $274.2 million in 2025, up 73% from 2024. These results provide context on the drug’s sales growth before the clinical update, but relate to an earlier period and do not change its current approval. The next step in the ACCEL program is the preliminary data readout expected in the second half of 2027. If the trial results are supportive, the company said it plans to submit a supplemental drug application to the U.S. Food and Drug Administration. Until then, IBSRELA’s use for chronic idiopathic constipation remains under clinical evaluation.