What happened

After upbeat results from a Phase 3 trial, shares of Ardelyx (NASDAQ:ARDX), a clinical-stage biotech focused on cardiorenal disease, rose as much as 23% in early-morning trading on Tuesday. Shares were up about 16% as of 10:37 a.m. EDT.

So what

Ardelyx reported positive results from its Phase 3 AMPLIFY study today. This trial was designed to test its experimental drug tenapanor in combination with phosphate binders as a hopeful treatment for patients with chronic kidney disease who are on dialysis.

Here are the key takeaways from the study:

  • Tenapanor met the study's primary endpoint and all key secondary endpoints.
  • Patients who received tenapanor showed a statistically significant (p = 0.0004) mean reduction in serum phosphorus from baseline of 0.84 mg/dL at the end of four weeks. That was much better than the control group, which showed a mean reduction of just 0.19 mg/dL.
  • Up to 49.1% of patients in the tenapanor group achieved a serum phosphorus of < 5.5 mg/dL. That compares favorably to a 23.5% result in the control group.
  • Patients in the tenapanor group showed a statistically significant 22% to 24% reduction in FGF23 levels when compared to the control group. That's important because elevated levels of FGF23 are associated with an increased risk of major cardiovascular events.
  • Tenapanor was well tolerated, with a 4.3% discontinuation rate. That compares to 2.5% in the control group.
  • There were no serious adverse events related to tenapanor.
Female doctor giving thumbs-up signal.

Image source: Getty Images.

Ardelyx's CEO Mike Raab was happy with the results:

We are thrilled with the positive results from the AMPLIFY study demonstrating that tenapanor can help significantly more patients achieve the established serum phosphorus treatment goal of less than 5.5 mg/dL. This result is striking as serum phosphorus levels above 5.5 mg/dL are associated with increased mortality. For too long, hyperphosphatemia management has been an enormous challenge for patients and clinicians. With tenapanor, patients may finally be able to achieve their treatment goal.

Traders are bidding up the stock in response to the encouraging clinical results.

Now what

Ardelyx is currently running another Phase 3 study called PHREEDOM that is testing tenapanor as a monotherapy. The company expects to share results from that trial in the fourth quarter. Once the PHREEDOM trial is complete, management plans to submit tenapanor for regulatory approval in monotherapy and combination therapy for the treatment of hyperphosphatemia.

Investing in biotech stocks can be risky, especially when the company is still in the clinical stage. However, Ardelyx could be on the cusp of becoming a commercial business, because tenapanor is currently pending FDA approval as a potential treatment for irritable bowel syndrome with constipation. A go/no go decision is expected to be handed down by Sept. 12, 2019, so investors won't have to wait long to learn more.

The back half of 2019 should be an exciting time for Ardelyx's investors. This Fool plans on following this company's progress with great interest.