Kidney Disease Drug Wins Breakthrough Therapy Designation

Kappa opioid receptor agonist treats uremic pruritus during hemodialysis

The FDA has granted breakthrough therapy status to CR845 (Cara Therapeutics), a peripherally acting kappa opioid receptor agonist, for the treatment of moderate-to-severe uremic pruritus (UP) in patients with chronic kidney disease (CKD) undergoing hemodialysis.

A breakthrough therapy designation is granted to expedite the development and review process for new therapies that address serious or life-threatening conditions, where preliminary clinical evidence indicates that the drug candidate may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints.

The FDA’s decision was supported primarily by positive top-line results from part A of a phase 2/3 clinical trial of CR845 in patients with UP. Part A of the trial met its primary endpoint, with a 68% reduction in worst itching scores compared with placebo after eight weeks of treatment (P < 0.0019). Part A also met the study’s secondary endpoint, with a 100% improvement in quality-of-life domains compared with placebo (P < 0.0007).

CR845 is a peripherally acting kappa opioid receptor agonist currently in development for the treatment of patients with acute and chronic pain and pruritus. In randomized, double-blind, placebo-controlled phase 2 trials, treatment with CR845 resulted in statistically significant reductions in pain intensity and opioid-related adverse events in patients undergoing laparoscopic hysterectomy or bunionectomy procedures.

In more than 1,200 subjects dosed to date, CR845 was well-tolerated, without incurring the dysphoric and psychotomimetic adverse effects that have been reported with centrally acting (CNS-active) kappa opioid receptor agonists, and lacking the respiratory depression and abuse liability of mu opioid receptor agonists, according to the drug’s developer.

UP is an intractable systemic itch condition that occurs with the greatest frequency and intensity in patients with CKD undergoing hemodialysis and peritoneal dialysis; however, pruritus has also been reported in CKD patients who were not yet on dialysis.

Studies have estimated the prevalence of UP to be approximately 40% of patients with end-stage renal disease (ESRD), with approximately 24% of patients reporting severe pruritus. Similarly, most dialysis patients (approximately 60% to 70%) report pruritus, with 30% to 40% reporting moderate or severe pruritus.

Source: Cara Therapeutics; June 23, 2017.