CymaBay Therapeutics, Inc. (NASDAQ: CBAY), a biopharmaceutical company focused on innovative therapies for patients with liver and other chronic diseases, today announced that The New England Journal of Medicine (NEJM) has published detailed results from the RESPONSE Phase 3 trial evaluating seladelpar, an investigational agent, and the only potent, selective peroxisome proliferator-activated receptor delta (PPARδ) agonist or delpar, being studied in adults with primary biliary cholangitis (PBC). Results showed rapid and sustained improvements in reducing cholestasis and liver injury, together with significant reductions in pruritus (itching) across the numerical rating scale (NRS), 5-D Itch Scale, and the PBC-40 questionnaire. Publication of these detailed findings from RESPONSE follows topline data presented as a late breaker at The Liver Meeting® 2023 of the American Association for the Study of Liver Diseases (AASLD) in November 2023.
RESPONSE was a double-blind, placebo-controlled, global study of one-year duration that randomized 193 people with PBC in a 2:1 ratio to receive seladelpar 10 mg or placebo, once daily. Eligible participants had an inadequate response or intolerance to ursodeoxycholic acid (UDCA) with alkaline phosphatase, or ALP ≥ 1.67× the upper limit of normal (ULN) after at least 12 months of treatment. The primary endpoint was a composite of ALP and total bilirubin at Month 12, which supported authorization for current second line treatment in PBC by the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) for registrational studies in PBC. The primary endpoint was achieved in 61.7% (79/128) of patients treated with seladelpar vs. 20.0% (13/65) treated with placebo (95% CI 27.7 to 53.4; P<0.001) at Month 12.
“Many people living with PBC do not experience a normalization of ALP or meaningful symptom relief with currently available treatments. Pruritus or severe itch significantly impairs the quality of life of our patients, and current second-line treatment frequently worsens itch. New options, that are potent, effective, and safe, are needed for people living with this chronic debilitating autoimmune condition,” said Gideon Hirschfield, M.D., Lily and Terry Horner Chair in Autoimmune Liver Disease Research, Toronto Centre for Liver Disease. “The RESPONSE data are genuinely exciting. The data, together with the existing substantial experience gained from prior studies, robustly support the potential for seladelpar to raise the bar in PBC treatment. In this rigorous international trial, people living with PBC saw substantial rates of normalization of serum liver tests, and clear statistically significant improvement in itch. Benefits were also noted in those people living with compensated cirrhosis.”
The key secondary endpoint of ALP normalization was reached in 25.0% (32/128) of patients treated with seladelpar vs. 0.0% for patients treated with placebo (95% CI 18.3 to 33.2; p<0.001). The average decrease in ALP for patients on seladelpar was 42.4% vs. 4.3% for patients on placebo. Compared to placebo, seladelpar reduced alanine aminotransferase (ALT) at Month 12 by 23.5% vs. 6.5% (p=0.003), and gamma-glutamyl transferase (GGT) by 39.1% vs. 11.4% (p<0.0001).
The study also measured change in patient-reported pruritus as a key secondary endpoint using the daily numerical rating scale (NRS; 0-10). Approximately 37.3% of patients enrolled had moderate-to-severe pruritus based on an NRS (0-10) score ≥ 4 at baseline. Improvement in pruritus was seen as soon as Week 4 and significance achieved at Month 6 among patients with baseline NRS > 4 reporting decreases of 3.2 points with seladelpar (n=49) vs. 1.7 for patients on placebo (n=23; least-squares mean difference -1.5 points, 95% CI -2.5 to -0.5; P<0.005). These improvements were sustained through Month 12 (p<0.005). A statistically significant reduction in pruritus was also observed at Month 6 and at Month 12 for patients in the intent-to-treat population, which includes all patients irrespective of their NRS score at baseline. Further, 5D-itch results in both the moderate-to-severe population and overall population, showed significance as early as 4 weeks which continued through Month 12 and had a positive impact on sleep. Similar results demonstrating reductions in itch and improvements in sleep were observed using the PBC-40 questionnaire.
Safety as reflected in adverse events (AEs) was similar in the seladelpar-treated and placebo-treated groups. The most common adverse events (AEs) in the study overall (≥10% in either the seladelpar or placebo group) were COVID-19 and pruritus. Consistent with the positive effect of seladelpar on pruritus NRS, pruritus AEs were reported more frequently in participants receiving placebo compared with seladelpar. Serious AEs (SAEs) were reported in 7.0% and 6.2% of seladelpar-treated and placebo-treated patients, respectively. No SAE occurred in more than one patient, and none were considered to be associated with seladelpar treatment.
“The publication of the pivotal Phase 3 data for seladelpar in The New England Journal of Medicine recognizes the importance of these findings, the potential of this investigational agent to help people living with PBC, and the significant need for innovation in this area,” said Charles McWherter, Ph.D., Chief Scientific Officer and President of Research and Development at CymaBay. “We are thrilled that these results are now available to benefit researchers, patients, and the broader medical community in our collective pursuit of PBC treatment transformation.”
A New Drug Application (NDA) for seladelpar for the treatment of primary biliary cholangitis, including pruritus in adults without cirrhosis or with compensated cirrhosis (Child Pugh A) who are inadequate responders or intolerant to UDCA, was accepted for priority review by the FDA in February 2024. This application reflects the updated breakthrough designation that was granted by the agency in October 2023. The company also plans to file marketing authorization applications in the first half of 2024 with the EMA where seladelpar has received Priority Medicines (PRIME) status and plans to file with the U.K. Medicines and Healthcare products Regulatory Agency (MHRA).
