In brief
What happens in psoriasis
Psoriasis is not "dry skin" or a cosmetic problem but chronic immune inflammation. The key players are the cytokines interleukin-23 and interleukin-12, along with type I interferons. They drive a cascade that makes skin cells divide many times faster than normal and sustains inflammation within the plaque.
The signal from those cytokines is carried into the cell by TYK2, a member of the Janus kinase family. Blocking it means switching off precisely the pathway on which psoriatic inflammation depends.
Why ordinary JAK inhibitors are a blunt instrument
Classic kinase inhibitors (tofacitinib, baricitinib, upadacitinib) bind the active site — where ATP docks to make the enzyme work.
The problem is that active sites are built similarly across related kinases. A drug that fits one inevitably engages its neighbours: JAK1, JAK2 and JAK3 govern haematopoiesis, immune surveillance and interferon signalling. Hence the FDA's class-wide boxed warning about serious infections, thrombosis, cardiovascular events and malignancy.
What was done differently
Besides its working domain, TYK2 has a regulatory (pseudokinase) domain — a part that normally holds the enzyme switched off.
Deucravacitinib binds precisely there. It does not occupy the keyhole; it fixes the adjacent lever in the "off" position.
| Classic JAK inhibitors | Deucravacitinib | |
|---|---|---|
| Binding site | Active site (ATP pocket) | Regulatory domain |
| Similarity of target across neighbouring kinases | High — hence cross-activity | Low — hence selectivity |
| Affects JAK1/2/3 | Yes | Essentially not at therapeutic doses |
| FDA boxed warning | Present | Absent |
| Formulation | Tablets | Tablets |
The design intent: obtain the anti-inflammatory effect along the required pathway without disturbing everything else.
What the trials showed
▸POETYK PSO-1 and PSO-2 (JAAD, 2023) — two phase 3 trials. Deucravacitinib outperformed both placebo and apremilast on the proportion of patients achieving PASI 75 (at least 75% improvement in the psoriasis severity index) and clear or almost clear skin on sPGA [1]. ▸Five-year open-label extension (Am J Clin Dermatol, 2026) — efficacy and safety profile maintained with long-term use [2]. ▸A separate analysis showed improvement begins early and holds through the maintenance phase [3].
How it is taken
| Parameter | Detail |
|---|---|
| Dose | 6 mg once daily |
| Titration | Not required |
| Food | Irrelevant |
| Formulation | Tablet |
The absence of titration is a practical advantage: the patient starts at the working dose without a build-up period.
What to check before and during
▸tuberculosis screening, including latent infection; ▸hepatitis B and C markers; ▸vaccination: live vaccines before starting, not during therapy; ▸baseline blood counts and liver tests before initiation, thereafter at the clinician's discretion.
There is no rigid laboratory schedule of the kind classic JAK inhibitors demand — a direct consequence of the different selectivity.
Where it sits in psoriasis treatment
| Step | Treatment |
|---|---|
| Mild psoriasis | Topicals: corticosteroids, vitamin D analogues, calcineurin inhibitors |
| Moderate | Phototherapy, methotrexate, apremilast, *deucravacitinib* |
| Severe, with joint involvement | Injectable biologics: IL-17, IL-23 and TNF inhibitors |
Deucravacitinib occupies the oral systemic niche: stronger than apremilast on trial comparisons and simpler to take, though in severe disease and psoriatic arthritis injectable biologics remain the more powerful option.
Summary
▸Allosteric mechanism: binding TYK2's regulatory domain rather than its active site. ▸Hence selectivity and the absence of the boxed warning typical of JAK inhibitors. ▸Efficacy above placebo and apremilast on PASI 75 and sPGA in phase 3 trials. ▸Convenience: 6 mg once daily, no titration, food irrelevant. ▸Monitoring lighter than for the JAK class, though tuberculosis and hepatitis screening is mandatory. ▸Does not replace injectable biologics in severe psoriasis and arthritis.
Treatment can be discussed at a consultation; the product can be ordered here.
References
1. Armstrong AW, et al. Deucravacitinib versus placebo and apremilast in moderate to severe plaque psoriasis: efficacy and safety results from the 52-week, randomized, double-blinded, placebo-controlled phase 3 POETYK PSO-1 trial. J Am Acad Dermatol. 2023;88(1):29–39. PMID 35820547
2. Armstrong AW, et al. Deucravacitinib 5-year safety and efficacy results in plaque psoriasis: a phase 3 open-label extension. Am J Clin Dermatol. 2026. PMID 42563042
3. Korman NJ, et al. Deucravacitinib onset of action and maintenance of response in phase 3 plaque psoriasis trials. J Dermatolog Treat. 2024. PMID 38945549
4. SOTYKTU (deucravacitinib) US Prescribing Information, Bristol Myers Squibb.
Key facts
- Deucravacitinib (brand name Sotyktu, Bristol Myers Squibb) is the first allosteric TYK2 inhibitor, approved by the FDA on 9 September 2022 for moderate-to-severe plaque psoriasis in adults.
- The key difference from ordinary JAK inhibitors: it binds the regulatory (pseudokinase) domain rather than the active site. Active sites are similar across related kinases while regulatory domains differ far more — hence the high selectivity.
- The practical consequence of that selectivity: the drug does not carry the FDA boxed warning about serious infections, thrombosis, cardiovascular events and malignancy that applies to the JAK inhibitor class.
- TYK2 transmits signals from interleukins 12 and 23 and type I interferons — precisely the cytokines that sustain psoriatic inflammation. Before this, blocking them required injectable biologics.
- POETYK PSO-1 and PSO-2 (JAAD, 2023): deucravacitinib outperformed both placebo and apremilast on PASI 75 response and on clear or almost clear skin by sPGA.
- A five-year open-label extension confirms that efficacy and the safety profile are maintained with long-term use.
- Dosing is simple and needs no titration: 6 mg once daily, with or without food — a practical advantage over drugs requiring dose escalation.
- Laboratory monitoring is lighter than for classic JAK inhibitors, but tuberculosis and viral hepatitis screening precedes treatment, and live vaccines are not given during therapy.
- Where it belongs: moderate-to-severe psoriasis when topical therapy is insufficient. It is an oral alternative to injectable biologics, not a replacement for them in severe disease.
- Apremilast is the direct competitor in the oral niche: deucravacitinib performed better in trials, but the choice still rests with the clinician given comorbidity and tolerability.
