FDA hands Cara, Vifor a consolation prize with Korsuva nod in pruritus for chronic kidney disease patients

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The FDA approval for anti-itch medication Korsuva is a win for the drug that has come up short as a treatment for atopic dermatitis and in an oral formulation. (Pixabay)

Chronic kidney disease patients on hemodialysis who suffer the relentless itch of pruritus finally have some relief.

The FDA has approved Cara Therapeutics and Vifor Pharma’s Korsuva for the condition. The drug, which is injected three times weekly, offers significant improvements in safety and effectiveness on the current variety of antihistamine treatments used to combat pruritus. 

The moderate to severe levels of the condition, for which the drug is approved, affect roughly 40% of the more than 500,000 chronic kidney disease patients on hemodialysis.

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“Because there are no approved therapies to treat moderate to severe pruritus for this patent population, Korsuva will help fill a significant unmet medical need," Eric Vandal, Cara’s vice president of commercial operations, said in a conference call.

Recognizing this, the FDA awarded Korsuva with a breakthrough-therapy designation and priority review leading up to Monday’s green light.

Cara of Stamford, Connecticut, developed the drug and added commercial partner Vifor of Switzerland. The companies expect to launch Korsuva in the first quarter of 2022 and hope to gain reimbursement and patient access through Medicare and Medicaid in the first half of 2022. Cara said it has not yet determined a price for the drug.

The nod was based on two phase 3 studies of 1,300 chronic kidney disease dialysis patients with moderate-to-severe pruritus, which showed that 40% and 37% of Korsuva recipients logged a four-point improvement from baseline on a measure of their most severe itch compared to 21% and 26% for those who received placebo.

The drug (difelikefalin) is an opioid agonist which targets the kappa opioid receptor in the peripheral nervous system as opposed to morphine and other opioid painkillers, which work by activating the mu opioid receptor in the central nervous system. By avoiding receptors in the brain and spinal cord, it is believed that the drug will not leave patients prone to the nausea, respiratory depression and abuse potential of traditional opioids. 

Korsuva comes with warnings about dizziness, sleepiness, mental status changes and gait disturbances. The treatment may cause impairment when driving a car or operating machinery. None of these side effects were evident in more than 7% of patients who received Korsuva in the trials. 

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The FDA go-ahead is something of a consolation prize for Korsuva, which struggled to show efficacy in a phase 2 trial for atopic dermatitis. Cara also has suffered setbacks in its attempt to develop an oral version of the drug.

Monday, however, the company sounded undaunted by the stumbling blocks. CEO Derek Chalmers believes that the approval can help Cara rediscover the promise it once envisioned for Kosuva.

"We're gonna have this income advantage which is going to fund that other part of the pipeline," said Chalmers, who then mentioned "oral Kosuva development, which broadens the application for Kosuva beyond hemodialysis and then to other patient populations."