How Clinical Trials Changed HS Treatment: A Timeline of the Studies Behind Today's Medicines

For a long time, people with hidradenitis suppurativa (HS), also called acne inversa, were treated with medicines and surgery borrowed from other conditions. There was no drug formally approved for HS. Antibiotics, hormonal treatments, retinoids and surgery were used based on experience rather than large trials designed specifically for the disease. That began to change in the last decade, and the reason is clinical research.

This article tells that story through the trials themselves — what the treatment landscape looked like before each step, what question each study asked, what the results added, and when (and whether) a medicine was approved. Throughout, it keeps two things carefully apart: what a trial showed and whether and when a regulator approved a medicine. Those are different events, sometimes years apart.

A note on dates: for each treatment we distinguish, where relevant, trial initiation, trial completion, results publication, regulatory submission, EU approval, US approval, and availability in everyday practice. Trial completion never automatically means approval.

Before 2015: treatment without an approved drug

Until the mid-2010s, HS care relied on options that were never specifically approved for it: topical and oral antibiotics, anti-inflammatory approaches, hormonal treatments, isotretinoinIsotretinoin: An oral retinoid primarily used for severe acne. It is sometimes tried in Acne Inversa, although evidence for its effectiveness in HS is limited. Use requires strict medical supervision due to potential side effects.IsotretinoinAn oral retinoid primarily used for severe acne. It is sometimes tried in Acne Inversa, although evidence for its effectiveness in HS is limited. Use requires strict medical supervision due to potential side effects.Read more in the glossary, pain management and surgery for established tunnelsSinus Tract: A tunnel-like channel under the skin that forms between abscesses or nodules. Sinus tracts indicate more advanced disease and can chronically drain fluid. They are associated with Hurley Stages II and III.Sinus TractA tunnel-like channel under the skin that forms between abscesses or nodules. Sinus tracts indicate more advanced disease and can chronically drain fluid. They are associated with Hurley Stages II and III.Read more in the glossary and scarring. Some helped some people, but the evidence base was thin and fragmented. The field needed properly designed trials in HS patients — and a treatment target.

Adalimumab: the first approved biologic for HS

The first target to succeed was tumour necrosis factor alpha (TNF-α), a signalling molecule involved in inflammation. AdalimumabAdalimumab: A biologic drug from the class of TNF-α inhibitors and the first medication officially approved for treating moderate-to-severe Acne Inversa. It is marketed under the brand name Humira® and as biosimilars.AdalimumabA biologic drug from the class of TNF-α inhibitors and the first medication officially approved for treating moderate-to-severe Acne Inversa. It is marketed under the brand name Humira® and as biosimilars.Read more in the glossary (brand name Humira, from AbbVie) is a TNF-α inhibitorTNF-α Inhibitor: A group of biologic drugs that block tumor necrosis factor alpha (TNF-α), a key inflammatory mediator. Adalimumab is the best-known TNF-α inhibitor approved for Acne Inversa.TNF-α InhibitorA group of biologic drugs that block tumor necrosis factor alpha (TNF-α), a key inflammatory mediator. Adalimumab is the best-known TNF-α inhibitor approved for Acne Inversa.Read more in the glossary already used in other inflammatory diseases. Researchers asked whether blocking TNF-α could calm the inflammation of HS.

The trials: two large Phase 3 studies, PIONEER I and PIONEER II, tested adalimumab against placeboPlacebo: An inactive substance, usually identical in appearance to the real drug, used in clinical trials to control for the meaningful placebo response in Acne Inversa.PlaceboAn inactive substance, usually identical in appearance to the real drug, used in clinical trials to control for the meaningful placebo response in Acne Inversa.Read more in the glossary in adults with moderate-to-severe HS. The main measure was HiSCRHiSCR (Hidradenitis Suppurativa Clinical Response): The dichotomous response criterion that became the regulatory standard in the adalimumab trials. HiSCR50 is met when: (1) the combined count of abscesses and inflammatory nodules drops ≥50%, (2) the number of abscesses does not increase, and (3) the number of draining tunnels does not increase. HiSCR75, HiSCR90, and HiSCR100 apply the same logic at higher thresholds.HiSCR (Hidradenitis Suppurativa Clinical Response)The dichotomous response criterion that became the regulatory standard in the adalimumab trials. HiSCR50 is met when: (1) the combined count of abscesses and inflammatory nodules drops ≥50%, (2) the number of abscesses does not increase, and (3) the number of draining tunnels does not increase. HiSCR75, HiSCR90, and HiSCR100 apply the same logic at higher thresholds.Read more in the glossary (Hidradenitis Suppurativa Clinical Response) — broadly, a meaningful reduction in inflammatory lesions. More patients on adalimumab reached that response than on placebo (in the range of about 42–59% versus roughly 26–28%, depending on the study).

Results, approval and the date gap: this is a textbook example of why dates matter. Regulators approved adalimumab for moderate-to-severe HS in 2015 — the European Commission on 30 July 2015 and the U.S. FDA on 10 September 2015 — making it the first medicine ever approved specifically for HS. The full PIONEER trial report was then published in the New England Journal of Medicine in 2016. Approval came before the journal publication because regulators review the underlying data directly.

What changed for patients: for the first time, doctors had an on-label, evidence-based biologicBiologic: A class of medications derived from living cells that target specific components of the inflammatory process. For Acne Inversa, biologics such as adalimumab and secukinumab are used when other treatments are insufficient.BiologicA class of medications derived from living cells that target specific components of the inflammatory process. For Acne Inversa, biologics such as adalimumab and secukinumab are used when other treatments are insufficient.Read more in the glossary for HS. What remained uncertain: not everyone responded, responses could fade over time, and there was a clear need for more options for people who did not benefit enough.

Secukinumab: adding the IL-17A pathway

The next breakthrough came from a different part of the immune system: the interleukin-17Interleukin-17 (IL-17): Inflammatory cytokines (IL-17A and IL-17F) that drive neutrophil recruitment and tissue damage in Acne Inversa. IL-17A is blocked by secukinumab; both IL-17A and IL-17F are blocked by bimekizumab.Interleukin-17 (IL-17)Inflammatory cytokines (IL-17A and IL-17F) that drive neutrophil recruitment and tissue damage in Acne Inversa. IL-17A is blocked by secukinumab; both IL-17A and IL-17F are blocked by bimekizumab.Read more in the glossary (IL-17) pathway, which drives inflammation in several skin diseases. SecukinumabSecukinumab: A biologic drug that inhibits the inflammatory messenger interleukin-17A (IL-17A). Secukinumab was approved as the second biologic for treating Acne Inversa and is available under the brand name Cosentyx®.SecukinumabA biologic drug that inhibits the inflammatory messenger interleukin-17A (IL-17A). Secukinumab was approved as the second biologic for treating Acne Inversa and is available under the brand name Cosentyx®.Read more in the glossary (brand name Cosentyx, from Novartis) blocks IL-17A.

The trials: SUNSHINE and SUNRISE were two identical Phase 3 studies — among the largest ever run in HS, with more than 1,000 participants across many countries. They compared secukinumab against placebo. At week 16, more patients on secukinumab reached HiSCR50 (a 50% reduction in inflammatory lesions) than on placebo — roughly 42–45% versus about 26–29%, with benefits maintained through week 52.

Results, publication and approval: the SUNSHINE and SUNRISE results were published in The Lancet in February 2023. The EMA’s expert committee gave a positive opinion in April 2023, and the European Commission approved secukinumab for HS on 1 June 2023. The U.S. FDA approved it for adults later in 2023, and the indication was subsequently expanded to adolescents. Here, publication and approval fell in the same year — a different pattern from adalimumab.

What changed for patients: secukinumab became the first new biologic option for HS in years, and the first working through IL-17A — important for people who had not responded well to TNF-α blockade. What remained uncertain: as with any treatment, not everyone responds, and head-to-head comparisons between biologics were limited.

Bimekizumab: blocking two IL-17 signals at once

BimekizumabBimekizumab: A monoclonal antibody blocking both IL-17A and IL-17F. Approved by the FDA on 20 November 2024 as the first IL-17A and IL-17F inhibitor for adults with moderate-to-severe HS; approved by the EMA in April 2024. Brand name: Bimzelx®.BimekizumabA monoclonal antibody blocking both IL-17A and IL-17F. Approved by the FDA on 20 November 2024 as the first IL-17A and IL-17F inhibitor for adults with moderate-to-severe HS; approved by the EMA in April 2024. Brand name: Bimzelx®.Read more in the glossary (brand name Bimzelx) is made by UCB. It is a dual inhibitor of both IL-17A and IL-17F — two related signals in the same inflammatory pathway. The idea was that blocking both might control inflammation more completely than blocking IL-17A alone.

The trials: BE HEARD I and BE HEARD II were two Phase 3 studies with a combined enrolment of just over 1,000 participants with moderate-to-severe HS. Bimekizumab improved the signs and symptoms of HS compared with placebo at week 16, and the benefit was sustained to week 48; longer open-label follow-up reported high response rates maintained over one to two years.

Results and approval: the Phase 3 results were published in The Lancet in 2024. The European Commission approved bimekizumab for moderate-to-severe HS in April 2024 — the first regulatory approval for this use anywhere — and the U.S. FDA approved it in November 2024. Bimekizumab was the first dual IL-17A/IL-17F inhibitor approved for HS.

What changed for patients: a third mechanism joined the toolbox, giving more choice when earlier treatments were not enough. What remained uncertain: long-term durability, how best to sequence the available biologics, and who benefits most from which mechanism are still active research questions.

A trial that did not succeed: vilobelimab

It is just as important to see that trials can show a treatment does not help enough. Vilobelimab (formerly IFX-1, from InflaRx) targets a different immune signal called C5a. In the Phase 2b SHINE study, top-line results reported in 2019 showed that vilobelimab did not meet its primary endpoint — there was no clear dose-dependent improvement in HiSCR at week 16, partly because the placebo group responded unusually strongly.

This is not a failure of the research; it is the research working. A well-run trial that returns a negative or inconclusive result prevents an ineffective treatment from being adopted, protects patients, and points investigators toward better ideas. (Later analyses continued to explore specific effects, illustrating how a single dataset can be re-examined — but the primary result stands.)

Other developments worth knowing

Several other programmes have shaped HS research and are best understood by their status:

• UstekinumabUstekinumab: An antibody against the shared IL-12/IL-23 p40 subunit. Used off-label in Acne Inversa with modest, inconsistent results. Brand name: Stelara®.UstekinumabAn antibody against the shared IL-12/IL-23 p40 subunit. Used off-label in Acne Inversa with modest, inconsistent results. Brand name: Stelara®.Read more in the glossary (an IL-12/IL-23 inhibitor) has been studied in HS but is not approved for it; it is used off-label in some settings — an investigational-for-HS treatment.
• JAK inhibitors taken by mouth, such as povorcitinibPovorcitinib: An oral, selective JAK1 inhibitor from Incyte (development name INCB54707). In March 2025 Incyte announced positive topline results from the pivotal Phase 3 STOP-HS program (STOP-HS1 and STOP-HS2) in adults with moderate-to-severe HS — both studies met their primary endpoint. Not yet approved at time of writing.PovorcitinibAn oral, selective JAK1 inhibitor from Incyte (development name INCB54707). In March 2025 Incyte announced positive topline results from the pivotal Phase 3 STOP-HS program (STOP-HS1 and STOP-HS2) in adults with moderate-to-severe HS — both studies met their primary endpoint. Not yet approved at time of writing.Read more in the glossary, have been studied in HS and remain investigational for this use at the time of writing.
• Numerous earlier and smaller studies of antibiotics, hormonal treatments and surgery built the practical foundation clinicians still rely on.

Because the field moves quickly, it is best to check a current, authoritative source for the latest approval status of any specific treatment.

Timeline of key HS clinical trials

The table below is the accessible text equivalent of the HS trial timeline. It does not rely on colour: every fact is in the cell. Scroll horizontally on small screens to read all columns.

Year(s)	Trial / programme	Treatment (target)	Phase	What was investigated	Principal result	Regulatory / clinical significance	Current status
Before 2015	—	Antibiotics, hormonal therapy, retinoids, surgery	—	Symptom control borrowed from other conditions	Variable; thin evidence base specific to HS	No drug approved specifically for HS	Still used as part of care
~2013–2015	PIONEER I & II	Adalimumab (TNF-α inhibitor)	Phase 3	Does blocking TNF-α reduce HS lesions vs placebo?	More reached HiSCR on adalimumab (~42–59%) than placebo (~26–28%)	EU approval 30 Jul 2015; US approval 10 Sep 2015 — first drug approved for HS; full report published 2016	Approved (moderate-to-severe HS)
~2019–2023	SUNSHINE & SUNRISE	Secukinumab (IL-17A inhibitor)	Phase 3	Does blocking IL-17A reduce HS lesions vs placebo?	More reached HiSCR50 (~42–45%) than placebo (~26–29%), sustained to week 52	Published Lancet Feb 2023; EU approval 1 Jun 2023; US approval 2023 (adults, later adolescents)	Approved (moderate-to-severe HS)
~2021–2024	BE HEARD I & II	Bimekizumab (dual IL-17A/IL-17F)	Phase 3	Does blocking IL-17A and IL-17F improve HS vs placebo?	Improved vs placebo at week 16, sustained to week 48; high response maintained longer term	Published Lancet 2024; EU approval Apr 2024 (first worldwide); US approval Nov 2024	Approved (moderate-to-severe HS)
2019 (top-line)	SHINE	Vilobelimab / IFX-1 (anti-C5a)	Phase 2b	Does blocking C5a improve HS vs placebo?	Did not meet primary endpoint; no clear dose-dependent HiSCR at week 16	Example that trials can show insufficient benefit	Did not succeed for this endpoint

What this history means for you

Every approved HS medicine you might discuss with a doctor today exists because people took part in trials and researchers measured the results honestly — including the trials that did not work. That is why appearing in a trial search, or reading about a promising study, is a starting point for a conversation, not a verdict about your treatment.

To go deeper, read what a clinical trial is for the underlying concepts, or what taking part may be like if you are considering contacting a centre. You can also see which HS studies are currently open in Germany or return to the clinical trials hub. For approved options in everyday care, see the treatment overview.