What happened

Shares of Cara Therapeutics (NASDAQ:CARA) were soaring 16.8% higher as of 10:49 a.m. EDT on Wednesday. The big jump came after the biotech announced results from a phase 3 clinical study evaluating its Korsuva injection in hemodialysis patients with moderate-to-severe chronic kidney disease-associated pruritus (CKD-aP).

Cara reported statistically significant improvement in the primary endpoint of the study -- the proportion of patients with a 3-point or greater reduction in mean worst itching intensity numerical rating scale (NRS) score -- for patients receiving Korsuva compared to placebo. There was also a statistically significant improvement in the proportion of patients with 4-point or greater reduction in mean worst itching intensity NRS score, a key secondary endpoint of the phase 3 study. On top of the positive efficacy results, Cara also stated that Korsuva injection was well-tolerated through 12 weeks of treatment.

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So what

Any time a clinical-stage biotech announces positive results for its lead candidate, it's good news. But today's results are especially great for Cara for several reasons.

The improvement in itching for patients receiving Korsuva was off the charts. The key metric in determining statistical significance in clinical studies is the p-value, a calculated probability of how meaningful the obtained results actually are. A p-value of 0.05 or less is considered to be statistically significant. For the primary endpoint in Cara's study, the p-value was 0.000019.

Cara Therapeutics CEO Derek Chalmers noted that the company was "particularly encouraged by the early [anti-itching] response with Korsuva injection." He said that the statistically significant difference between Korsuva and placebo was observed after only one week of treatment. Even better, the significant benefit from Korsuva was sustained through 12 weeks.

Also, Korsuva didn't raise any safety concerns. There were some adverse events for patients in the phase 3 study, but they were similar across patients taking Korsuva and those on placebo. The most common adverse event was diarrhea, which was reported for 9.5% of the patients receiving Korsuva injection versus 3.7% of the patients in the placebo group. 

Now what

This was a critical step for Cara, but there are still a couple of hurdles to jump. The biotech must complete another ongoing phase 3 clinical study of Korsuva injection in treating CKD-aP patients on hemodialysis. Cara expects to announce the results from this second study later this year. If those results are positive, the company will move quickly to file for U.S. regulatory approval of the drug.

There's no sure thing when it comes to the regulatory approval process. But based on what Cara announced today, the chances of eventual approval of Korsuva in the CKD-aP indication appear to be quite good. 

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