Mechanism of Action

JYSELECA is a JAK1-preferential inhibitor1

JYSELECA is indicated for the treatment of moderate to severe active rheumatoid arthritis in adult patients who have responded inadequately to, or who are intolerant to one or more disease-modifying antirheumatic drugs (DMARDs). JYSELECA may be used as monotherapy or in combination with methotrexate (MTX).1

What is the role of JAK1 in RA?

Balancing inhibition of proinflammatory cytokine signalling via JAK1 and limiting impact on JAK2- and JAK3-related physiological functions2,*

Image is illustrative and based on in vitro findings; clinical relevance is unknown. There are currently no head-to-head trials between JAK inhibitors.

* The role of JAK1 is not limited to proinflammatory cytokine signalling. These cytokines signal via JAK pairs, though they may depend predominantly on one JAK more than another for signalling. For example, IL-6 and IFN-γ both signal through JAK1/JAK2, but IL-6 may predominantly signal through JAK1, whereas IFN-γ is more dependent on JAK2.2

JYSELECA is a JAK1-preferential inhibitor1

JYSELECA has a 5-fold potency for JAK1 vs JAK2, JAK3, and TYK2 in biochemical assays1

The relevance of inhibition of specific JAK isoforms to therapeutic effectiveness or safety is not currently known.

Watch JYSELECA in action

Striking a balance in JAK inhibition

In a study conducted by Traves et al., JYSELECA’s strength of balance is showcased in the first study to combine in vitro inhibition of cytokine responses in whole blood with clinical pharmacokinetics of JYSELECA, baricitinib, tofacitinib, and upadacitinib.2

Hear from research scientist Dr Traves about the role of JAK1-preferential inhibition in RA.


Differential cytokine impact of JAK inhibitors

JYSELECA’s inhibition of JAK1-dependent cytokines IFN-α and IL-6 is comparable to other JAK inhibitors, but with less inhibition of JAK2- and JAK3-dependent cytokines2


Fold-increase in IC50a across JAK-associated cytokines2

Adapted from Traves et al.2
Data are based on in vitro whole-blood assays; clinical relevance is unknown. There are currently no head-to-head trials between JAK inhibitors.
a IC50 indicates how much of a specific pharmacologic agent is required to inhibit a given biological activity by half.
b Data are normalised against IFN-α.

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See what it means to strike a balance on the full JYSELECA website

GM-CSF, granulocyte-macrophage colony-stimulating factor; IC, inhibitory concentration; IFN, interferon; IL, interleukin; JAK, Janus kinase; JAKi, Janus kinase inhibitor; NK, natural killer; RA, rheumatoid arthritis; TYK, tyrosine kinase.

References: 1. JYSELECA (filgotinib) Summary of Product Characteristics. Galapagos NV; 2022. 2. Traves PG, Murray B, Campigotto F, Galien R, Meng A, Di Paolo JA. Ann Rheum Dis 2021;80(7):865-875. 3. Malemud CJ. Int J Mol Sci. 2017;18(3):1-9. 4. Tan S, Xu J, Lai A, et al. Mol Med Rep. 2019;19(3):2057-2064. 5. Clark JD, Flanagan ME, Telliez JB. J Med Chem. 2014;57(12):5023-5038. 6. Schwartz DM, Kanno Y, Villarino A, Ward M, Gadina M, O’Shea JJ. Nat Rev Drug Discov. 2017;16(12):843-862. 7. Virtanen AT, Haikarainen T, Raivola J, Silvennoinen O. BioDrugs. 2019;33(1):15-32.

The most frequently reported adverse reactions were nausea (3.5%), upper respiratory tract infection (3.3%), urinary tract infection (1.7%), and dizziness (1.2%).1

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected

adverse reactions via the national reporting systems and to

Summary of Product Characteristics