Ardelyx announces positive results from RDX022 clinical study for treatment of hyperkalemia

Ardelyx, Inc. (NASDAQ: ARDX), a clinical-stage biopharmaceutical company focused on gastrointestinal and cardio-renal diseases, today announced positive results of an open label clinical study evaluating the pharmacodynamic (PD) activity of RDX022 in healthy adult volunteers. The study demonstrated that RDX022, Ardelyx's proprietary potassium binder for the treatment of hyperkalemia, effectively binds potassium in the gastrointestinal tract supporting plans to proceed with a Phase 3 clinical program currently expected to begin in the second half of 2016. RDX022 was generally well-tolerated at all doses administered (up to 27.5 g/day) in the study.

"The magnitude of effect seen with RDX022 in healthy adults supports our belief that, if approved following the completion of the Phase 3 clinical program, RDX022 will be an important agent in treating patients with hyperkalemia. We believe that RDX022 may be able to address many of the limitations of current and recently approved therapies due to the absence of sodium as a counter-ion in RDX022 as well as its improved palatability," said Mike Raab, President and Chief Executive Officer of Ardelyx. "We have leveraged the long-standing experience of our management team in creating, developing, and commercializing polymer-based drugs to create a proprietary, differentiated potassium binder that we believe can be brought to market utilizing the 505(b)(2) regulatory pathway. We look forward to starting a Phase 3 clinical program in the second half of 2016. We are fully committed to developing high-impact and important products for patients with cardio-renal diseases. We believe that RDX022 will complement our efforts with tenapanor, our small molecule drug candidate currently in Phase 2b for the management of hyperphosphatemia in dialysis patients."

Results from the PD study

This open-labeled pharmacodynamic (PD) study of RDX022 consisted of a two-day treatment-free baseline period and a four-day treatment period. The study included four cohorts, and in each cohort, 12 subjects received RDX022 and three subjects received a similar dose of sodium polystyrene sulfonate (SPS) for a total of 60 subjects.

RDX022 was administered at 4.6 g BID (9.2 g/day), 6.9 g BID (13.8 g/day), 4.6 g TID (13.8 g/day) and 9.2 g TID (27.5 g/day), and resulted in a mean increase of fecal potassium from baseline of 888 mg/day, 1,791 mg/day, 1,408 mg/day, and 1,670 mg/day, respectively. RDX022 was generally well-tolerated at all doses and demonstrated comparable results to those observed with sodium polystyrene sulfonate (SPS). Other fecal electrolytes were monitored during the study and no unexpected changes were observed; in particular, fecal magnesium remained unchanged from baseline. The results of the study will be presented in a future scientific format.

Mr. Raab also noted, "As we considered alternatives, we made the decision to formulate RDX022 with a calcium counter-ion. Given that we are trying to accomplish the management of hyperkalemia in chronic kidney disease and heart failure patients, we believe calcium is a more appropriate counter-ion than is sodium. It is clear that increasing the daily intake of sodium in these patients is counter to best clinical practice. Additionally, we have focused on improving both the physical properties of the polymer and the formulation of RDX022. Our goal for RDX022 is to develop as optimal a potassium binder as possible by combining innovation with existing technologies in a delivery form that aims to improve patient adherence and compliance. We believe these qualities would provide RDX022 with the potential to give us an advantage in this growing and important marketplace," commented Mr. Raab.