- Cara Therapeutics said its experimental drug Korsuva reduced itching symptoms in dialysis patients experiencing a condition called chronic kidney disease-related pruritis.
- The Phase 3 trial was the second to report data and paves the way for regulatory submission later this year.
- The drug is infused after dialysis sessions to patients with failing kidneys, who often suffer excessive itchiness because of inflammation and other factors. Cara estimates 40% of dialysis patients experience excessive itchiness.
Cara’s hypothesis in developing Korsuva was that by acting on opioid receptors, the experimental drug could provide relief from itching without leading to addiction. Rather than stimulating the mu-opioid receptor, like morphine and other pain drugs with addictive potential, Korsuva activates kappa opioid receptors.
The global Phase 3 KALM-2 trial enrolled 473 patients to receive either Korsuva or a placebo after each dialysis session, with a goal of reducing the severity of their worst itch by at least three points on a 10-point scale. Of patients treated with Korsuva, 54% reported a three-point reduction, significantly more than the 42% taking placebo.
The 54% of Korsuva patients reporting a three-point reduction in KALM-2 looks similar to the 51% that reported the same in the U.S.-based Phase 3 KALM-1 trial, although in that U.S. trial just 28% of patients in the placebo arm reported a three point reduction. However, trials of experimental pain-relief medication are often plagued by variable responses from placebo patients, making it a tricky area of drug development.
The Food and Drug Administration has granted breakthrough designation to Korsuva, which speeds up its coming review. The company estimates that 500,000 patients a year undergo dialysis, representing a large population in need of itch relief.
The company said it will submit an approval application to the FDA sometime in the second half of 2020, and its commercialization partner Vifor Fresenius Medical Care Renal Pharma will ask the European Medicines Agency for the green light shortly thereafter.
Cara is also developing an oral version of Korsuva for the non-dialysis population. The company announced results from a Phase 2 trial in December, in which the drug was able to provide itch relief when compared to placebo.
However, the magnitude of the results weren't as stark as they have been with the intravenous formulation. The drug failed to hit the three-point threshold for itch relief, and didn't hit significantly impact quality of life scores, prompting a sell-off of shares.