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Presentation

Phase 2 Trial of Oral Difelikefalin for Chronic Kidney Disease–Associated Pruritus

Description

The speaker describes a phase 2 double-blind, placebo-controlled trial of oral difelikefalin, a kappa-opioid agonist, for chronic kidney disease–associated pruritus in non-dialysis patients with moderate to severe itch. They explain that CKD itch is common even before dialysis, affects about 30% of patients, and significantly harms sleep, mood, and quality of life, yet there are no approved oral treatments for this population. The trial tested 0.25, 0.5, and 1 mg doses over 12 weeks, with worst itch NRS at week 12 as the primary endpoint; the 1 mg dose met the endpoint and produced meaningful itch relief, with about 65% achieving the FDA-relevant four-point itch reduction. Safety was generally mild to moderate, with fatigue and dizziness noted but overall good tolerability. The speaker argues this supports kappa-opioid receptor targeting as a systemic anti-itch strategy and emphasizes that itch is a neurobiological disease, not just an inflammatory skin problem. They end by noting the oral drug is not currently available because the company behind it went bankrupt, despite the approach remaining promising.

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Conclusions

Oral difelikefalin appears to provide rapid and clinically meaningful itch reduction in patients with chronic kidney disease and moderate-to-severe pruritus.
The 1.0 mg dose was the most effective and met the study’s primary endpoint, with benefits seen as early as week 2 and sustained through week 12.
A substantial proportion of patients achieved a large itch improvement, suggesting the response was not only statistically significant but also clinically important.
The treatment was generally well tolerated, with mainly mild-to-moderate adverse effects such as dizziness, gastrointestinal symptoms, and fatigue.
The results support kappa-opioid receptor activation as a promising systemic anti-itch strategy.
The findings suggest CKD-associated itch is a neurobiologic disease that can be treated pharmacologically, not just a symptom of skin inflammation.
The study highlights a major unmet need because there are currently no approved oral therapies for non-dialysis CKD-related itch.
Despite the promising efficacy, the speaker notes the drug’s availability is currently limited by the company’s bankruptcy.

Kim et al. Role of kappa-opioid and mu-opioid receptors in pruritus: Peripheral and central itch circuits. Exp Dermatol. 2022;31:1900-1907.#10.25251/skin.5.supp.31
Mahmoud et al., 2024.
Labib et al., 2022.