Incyte Corporation announced compelling 24-week interim data from its pivotal Phase 3 STOP-HS clinical trial program, demonstrating that povorcitinib (INCB54707), an oral JAK1 selective inhibitor, maintains clinically meaningful improvements in patients with moderate to severe hidradenitis suppurativa (HS) through extended treatment periods. The data, presented at the European Association of Dermatology and Venereology (EADV) 2025 Congress, will support planned regulatory submissions in Europe and the United States.
Sustained Clinical Response Rates
The extended follow-up data revealed that nearly 60% of efficacy-evaluable patients in both povorcitinib treatment groups (45 mg and 75 mg once daily) achieved HiSCR50 at Week 24, representing at least a 50% reduction from baseline in total abscess and inflammatory nodule count with no increase in abscess or draining tunnel count.
Across both STOP-HS1 and STOP-HS2 studies, patients demonstrated progressive improvements in higher threshold response rates through 24 weeks. HiSCR75 was achieved by 31.0%-40.3% of patients, HiSCR90 by 13.8%-27.7%, and HiSCR100 by 9.2%-21.3% of povorcitinib-treated patients, indicating substantial clinical benefit for a significant proportion of participants.
The 12-week versus 24-week HiSCR50 response rates showed sustained or improved efficacy over time. In STOP-HS1, the 45 mg dose achieved 40.2% response at 12 weeks versus 52.9%-64.0% at 24 weeks, while the 75 mg dose showed 40.6% at 12 weeks versus 50.0%-62.7% at 24 weeks. Similar patterns were observed in STOP-HS2, with the 45 mg dose improving from 42.3% at 12 weeks to 57.1%-58.0% at 24 weeks, and the 75 mg dose from 42.3% to 56.3%-58.5%.
Significant Pain Reduction Benefits
A particularly notable finding was the rapid and sustained improvement in skin pain scores. Povorcitinib-treated patients achieved greater improvements in skin pain beginning at the first post-baseline visit (Week 3) and continuing through Week 24. Remarkably, 62%-70% of povorcitinib-randomized patients achieved skin pain scores of mild or no pain at Week 24, representing a substantial improvement in this debilitating symptom.
Draining Tunnel Resolution
Patients receiving povorcitinib also demonstrated impressive rates of complete draining tunnel resolution. Among those with at least one draining tunnel at baseline, 34.6% and 41.6% of patients receiving 45 mg and 75 mg doses respectively achieved dt100 (100% decrease in draining tunnels) at Week 12, with rates improving to 39.0% and 50.6% at Week 24.
Safety Profile Remains Favorable
The overall safety profile of povorcitinib remained consistent with previous data, with both doses well tolerated through 24 weeks. Treatment-emergent adverse events occurred in 42.4%-54.3% of patients who transitioned from placebo to povorcitinib at Week 12, and 70.2%-78.7% for patients initially randomized to povorcitinib through Week 24.
Serious adverse events were observed in 2.9%-4.8% of patients, while adverse events of special interest occurred in 0%-1.4% of patients. Importantly, no major adverse cardiac events or deaths occurred during the 24-week treatment period.
Clinical Context and Regulatory Path
"HS remains a challenging and often debilitating condition and many patients are in need of new, well-tolerated and effective therapies that address prominent signs and symptoms of the disease, including inflammatory lesions and pain," said Pablo J. Cagnoni, M.D., President and Head of Research and Development at Incyte.
Dr. Martina Porter, STOP-HS study investigator and Assistant Professor of Dermatology at Harvard Medical School, emphasized the clinical significance: "HS is a complex and often misunderstood condition that can profoundly affect patients' daily lives. Data from the STOP-HS clinical trial program highlight the potential of povorcitinib to address key signs and symptoms for those living with HS."
Study Design and Patient Population
The STOP-HS program comprises two Phase 3 studies (STOP-HS1 and STOP-HS2), each enrolling approximately 600 adult patients (≥18 years) with moderate to severe HS. Eligible patients had a total abscess and inflammatory nodule count of ≥5, lesions in at least two distinct anatomical areas, and documented inadequate response to conventional systemic therapies.
Both studies feature a 12-week double-blind, placebo-controlled treatment period, followed by a 42-week extension period and 30-day safety follow-up. The primary endpoint is the proportion of patients achieving HiSCR50 at Week 12, with multiple secondary endpoints evaluating higher response thresholds, pain reduction, and flare prevention.
Disease Burden and Unmet Need
Hidradenitis suppurativa affects more than 150,000 patients in the United States with moderate to severe disease. This chronic inflammatory skin condition is characterized by painful nodules and abscesses that can lead to irreversible tissue destruction and scarring. Over-activity of the JAK/STAT signaling pathway is believed to drive the inflammation involved in HS pathogenesis and progression.
The positive 24-week data support Incyte's planned regulatory submissions for povorcitinib in HS, with European submissions expected in 2025 and United States submissions in early 2026. Povorcitinib is also being evaluated in Phase 3 trials for vitiligo and prurigo nodularis, as well as Phase 2 trials for asthma and chronic spontaneous urticaria.
