PMID-32405581 – Difelikefalin KALM-2 Chronic Pruritus Hemodialysis RCT
Fishbane S, Mathur V, Engel B, et al. "Randomized Controlled Trial of Difelikefalin for Chronic Pruritus in Hemodialysis Patients," J Am Soc Nephrol, 2020;31(7):1554-1564.
Quick Reference
| Property | Value |
|---|---|
| PMID | 32405581 |
| DOI | 10.1681/ASN.2020030340 |
| Year | 2020 |
| Journal | Journal of the American Society of Nephrology |
| Study Type | Randomized Controlled Trial (Phase III) |
| Evidence Level | I |
| Sample | n=473 hemodialysis patients with moderate-to-severe pruritus |
| Peptide(s) Studied | Difelikefalin |
Key Findings
- Confirmed KALM-1 results: difelikefalin significantly reduced pruritus vs placebo
- 37.7% of difelikefalin patients achieved >=3-point WI-NRS improvement vs 25.5% placebo (P=0.003)
- Significant improvements across all secondary itch endpoints
- Consistent efficacy across subgroups (age, sex, race, baseline pruritus severity)
- Safety profile consistent with KALM-1: no CNS opioid effects, no dependence
- No evidence of abuse potential or withdrawal symptoms
- Together with KALM-1, provided the confirmatory efficacy data for FDA approval
Study Design
Multicenter, randomized, double-blind, placebo-controlled Phase III trial (KALM-2). Design identical to KALM-1. Hemodialysis patients with moderate-to-severe CKD-associated pruritus randomized to IV difelikefalin 0.5 mcg/kg or placebo 3x/week for 12 weeks. Followed by 52-week open-label extension.
Limitations
- Same limitations as KALM-1: 12-week blinded phase, IV-only, HD-specific
- Slightly lower absolute response rate than KALM-1 (37.7% vs 49.1%)
- Placebo response rate 25.5% complicates interpretation
- Open-label extension introduces bias for long-term data
Clinical Relevance
KALM-2 is the confirmatory Phase III trial that, together with KALM-1, provided the regulatory basis for FDA approval of difelikefalin in August 2021. The consistent results across two large Phase III trials strengthen the evidence for peripheral kappa-opioid agonism as a viable therapeutic strategy. The pooled analysis of both KALM trials (PMID-36016762) further confirmed robust efficacy and safety. This approach of designing peptides that cannot cross the blood-brain barrier represents an important pharmacological principle applicable to other therapeutic areas.
Related
#research #RCT #evidence-level-I #difelikefalin #fda-approved