Our pipeline of gut-restricted therapies is concentrated on providing better medicines in two therapeutic areas: GI and cardiorenal diseases.

OUR GASTROINTESTINAL PROGRAMS

Tenapanor for Irritable Bowel Syndrome with Constipation (IBS-C)

Tenapanor, discovered and developed by Ardelyx, is a first-in-class, oral, experimental medication that works exclusively in the gut and is in late-stage clinical development. It has a unique mechanism of action that, in IBS-C, relieves both constipation and abdominal pain. By inhibiting, or blocking, the NHE3 transporter in the GI tract, tenapanor reduces the absorption of dietary sodium into the blood stream. Blocking NHE3 results in an increase in the amount of sodium in the gut. This increased sodium leads to an increase of fluid in the gut, which loosens stool, helping to relieve constipation. Based upon preclinical findings, we believe that tenapanor works to reduce abdominal pain caused by IBS-C through the inhibition of TRPV-1 dependent signaling. TRPV-1, better known as the “hot chili pepper receptor,” is a well-established pain target known for transmitting painful stimuli from a variety of sources including heat, protons and inflammatory molecules. We presented preclinical findings on this mechanism at the 2017 American Society of Gastroenterology Annual Meeting.

Tenapanor has been specifically designed to work exclusively within the GI tract, thereby significantly reducing the amount of drug that is absorbed into the bloodstream and the potential side effects that could occur.

IBS-C is a burdensome GI disorder affecting a significant number of people. It is characterized by significant abdominal pain, constipation, straining during bowel movements, bloating and/or gas.

Tenapanor’s safety and efficacy for the treatment of IBS-C were evaluated in our Phase 3 T3MPO program. This consisted of three studies – T3MPO-1 and T3MPO-2, which we reported positive data from in 2017 – and T3MPO-3, a long-term safety study which is now complete. Based on the findings from this program, we are preparing our New Drug Application for submission to the U.S. Food and Drug Administration for tenapanor for IBS-C in the second half of 2018.

Learn More About Our Completed Trials in IBS-C

IBS-C

IBS-C presents a significant burden on patients, the healthcare system and the U.S. economy. While estimates vary, it is projected that approximately 11 million people in the U.S. suffer from IBS-C.

RDX8940

RDX8940 is a minimally absorbed, oral TGR5 agonist for which we submitted an IND in late 2016. We are considering pursuing multiple GI indications for the development of RDX8940. Given pre­clinical data we’ve generated, we are evaluating the development of RDX8940 for the treatment of patients with nonalcoholic steatohepatitis (NASH), a serious and devastating condition affecting the liver, and other gastrointestinal indications.

TGR5 is an important receptor present on the surface of cells that line the GI tract that is activated in response to the bile acids the body secretes when we ingest food. As part of a normal physiological response, the binding of bile acids to TGR5 stimulates the production of critical metabolic hormones such as those involved in the maintenance of the body’s reaction to nutrients and the maintenance and care of the structural integrity of the gut. In people with certain conditions, the body’s regulation of critical hormones is disrupted and the body does not properly manage sugar and fat metabolism. Two of the many potential outcomes of this are inflammation and the accumulation of fat in the liver, which can cause NASH.

Elevated levels of phosphorus in the blood, a metabolic disorder known as hyperphosphatemia, is a very common and difficult-to-treat condition in patients with end-stage renal disease (ESRD) who require dialysis.

In February 2017, we reported positive data from the first Phase 3 clinical trial in these patients. The responder population (n=80 out of 164) had a mean reduction in serum phosphorus from baseline to the end of the eight-week treatment period of 2.56 mg/dL, with a reduction of up to 5.7 mg/dL. Notably, in this group, 33 percent of patients had a reduction in serum phosphorus of greater than 3 mg/dL. The study demonstrated a statistically significant difference in change of serum phosphorus levels from the end of the eight-week treatment period to the end of the four-week randomized withdrawal period between the tenapanor-treated group and the placebo-treated group in the responder patient population (mean -1.01 mg/dL, median of -1.3 mg/dL) and met its primary endpoint (95% CI -1.44, -0.21; LSmean -0.82mg/dL; p=0.01). Only 7.8 percent of patients discontinued treatment due to GI side effects.

We plan to initiate a second Phase 3 trial of tenapanor in this patient population following finalization of the protocol.

Learn More About Our Completed Trial in Hyperphosphatemia

In February 2015, we reported positive data from our Phase 2b clinical study evaluating tenapanor for the treatment of hyperphosphatemia in ESRD patients on dialysis. The study met its primary endpoint by demonstrating a statistically significant dose-related decrease in serum phosphorus levels for tenapanor-treated patients compared to patients receiving placebo.

Hyperphosphatemia

Hyperphosphatemia is commonly seen in patients with end-stage renal disease (ESRD), the most advanced stage of chronic kidney disease, who are on dialysis. Hyperphosphatemia is characterized by a build-up of excess phosphorus, a vital element that is normally kept in balance by the kidneys, with excess phosphorus removed and excreted in urine. In patients with kidney failure, phosphorus that comes from the food we eat builds up to abnormal levels and leads to bone disease, heart disease and is correlated with a higher risk of death in those patients.

HYPERKALEMIA

Hyperkalemia is a potentially life-threatening condition in which blood levels of potassium are elevated above normal. Potassium is a nutrient that is critical to the normal function of nerve and muscle cells, including those in the heart. Normal potassium blood levels are tightly balanced and maintained primarily by the kidneys. For people with heart failure, chronic kidney disease and diabetes, and particularly those also taking highly beneficial renin-angiotensin-aldosterone system inhibitors (RAASi), there is a greater risk of developing hyperkalemia due to the side effects of those drugs and the kidney’s limited ability to keep potassium in balance.

Our RDX013 program is aimed at discovering and evaluating orally administered small molecule therapeutic candidates that modulate the secretion of potassium in the GI tract. We have demonstrated proof-of-concept in this program showing potassium secretion in preclinical models of disease, and believe that RDX013 could potentially offer a future treatment option for hyperkalemia. Learn more about our RDX013 program.