Bimekizumab
IL 17A and IL 17F antibody for psoriasis and axial spondyloarthritis
Bimekizumab is a humanised monoclonal IgG1 antibody developed by UCB Pharma and authorised by the European Medicines Agency in 2021 under the brand name Bimzelx for treatment of moderate to severe plaque psoriasis in adults. Authorisations for psoriatic arthritis and axial spondyloarthritis followed in 2023. Bimekizumab is currently the only available antibody that simultaneously neutralises both IL 17A and IL 17F, two central cytokines of the inflammatory axis in psoriatic diseases.
Phase III trials such as BE VIVID, BE READY and BE SURE showed remarkably high response rates in plaque psoriasis: at week 16 about 85 percent of patients achieved a 90 percent improvement on the PASI score, and around 60 percent became clear (PASI 100). These results exceed those of previously available IL 17A selective antibodies such as secukinumab or ixekizumab. For patients with stubborn psoriasis, bimekizumab is a significant therapeutic advance.
Mechanism of Action
Interleukin 17 is a pro inflammatory cytokine that plays a key role in the pathogenesis of inflammatory skin disease and spondyloarthritis. The family includes IL 17A and IL 17F, which exist as homodimers and as the heterodimeric IL 17A/F. Both activate the IL 17 receptor complex (IL 17RA/RC) and drive the expression of antimicrobial peptides, chemokines and further pro inflammatory cytokines in keratinocytes, synoviocytes and endothelial cells.
Selective antibodies such as secukinumab and ixekizumab block IL 17A only. Bimekizumab binds both IL 17A and IL 17F with high affinity and therefore also neutralises heterodimers. This dual blockade suppresses the inflammatory cascade more completely and explains the above average clinical efficacy.
The half life is about 23 days. Subcutaneous administration reaches therapeutic plasma concentrations within a few days. As with other monoclonal antibodies, elimination is predominantly via proteolytic degradation, so no hepatic or renal dose adjustments are needed.
Indications
- Moderate to severe plaque psoriasis in adults who are candidates for systemic therapy
- Active psoriatic arthritis in adults after inadequate response to conventional DMARDs or TNF inhibitors
- Active axial spondyloarthritis including ankylosing spondylitis and non radiographic form
- Hidradenitis suppurativa in adults with moderate to severe disease (indication extension in 2024)
Dosage and Administration
Plaque psoriasis: 320 mg (two 160 mg pre filled syringes) subcutaneously at weeks 0, 4, 8, 12 and 16, then every 8 weeks. In patients over 120 kg with inadequate response, continued 4 weekly dosing may be considered. Psoriatic arthritis and axial spondyloarthritis: 160 mg every 4 weeks; in psoriatic arthritis with concurrent moderate to severe plaque psoriasis 320 mg every 4 weeks for 16 weeks, then 320 mg every 8 weeks.
Inject into the thigh, abdomen (at least 5 cm from the navel) or upper arm. Rotate injection sites within a body region to avoid local reactions. The first doses are usually given under medical supervision; after training, self injection is possible.
Renal and hepatic impairment: no dose adjustment required, pharmacokinetics are not meaningfully influenced by either organ function. Older patients over 65 years: no dose adjustment, clinical experience in the very old is limited.
Side Effects
Very common (over 10 percent): upper respiratory tract infections, oral candidiasis (markedly more frequent than under IL 17A selective blockers, in up to 14 percent of patients).
Common (1 to 10 percent): headache, skin fungal infections, folliculitis, fatigue, rash, diarrhoea, acne, injection site reaction, gastroenteritis, conjunctival infection.
Uncommon to rare: reactivation of latent tuberculosis, severe invasive fungal infections, new onset or exacerbation of inflammatory bowel disease, hypersensitivity reactions, neutropenia.
Important note on candidiasis: oral and pharyngeal candidiasis is usually superficial and well controlled with topical or oral antifungals. Preventive oral hygiene and prompt action on whitish plaques or tongue burning reduce the risk of severe courses.
Interactions
- Live vaccines (MMR, varicella, yellow fever, zoster live vaccine): avoid during therapy and for at least 5 half lives after the last dose (about 4 months)
- Inactivated vaccines: can be given, immune response partly attenuated, annual boosters particularly for influenza and pneumococcus are recommended
- Other biologic therapies (TNF inhibitors, IL 12/23 blockers): combination is not recommended because of additive infection risk
- Methotrexate, ciclosporin, conventional DMARDs: combination in psoriatic arthritis is possible with intensified monitoring
- CYP substrates: biologics theoretically affect CYP enzymes by reducing systemic inflammation, clinically usually not relevant
Special Notes
Screening before therapy: tuberculosis (interferon γ release assay or Mantoux test), hepatitis B and C serology, HIV status when appropriate. Check vaccination status and refresh live vaccines at least 4 weeks before starting therapy.
Inflammatory bowel disease: in known ulcerative colitis or Crohn's disease, use bimekizumab cautiously. Under IL 17 blockade, cases of new onset or flare of IBD have been reported. New abdominal symptoms during therapy require gastroenterological evaluation.
Pregnancy: experience is limited. When pregnancy is planned or confirmed, review the indication and pause therapy where appropriate. IgG antibodies cross the placenta from the second trimester. Breastfeeding: passage into breast milk is not fully quantified, breastfeeding during therapy is not routinely recommended; individual assessment is needed.
Monitoring: clinical response by PASI or BASDAI, infection signs, regular oral mucosa review, liver and renal values, blood count and lipids. Consider change of therapy if no improvement after 16 weeks.
You might also be interested in
- Secukinumab, IL 17A selective antibody in psoriasis
- Ustekinumab, IL 12/23 blocker in psoriasis and Crohn's disease
- Dupilumab, IL 4 and IL 13 blocker in atopic dermatitis
- Methotrexate, classic DMARD in psoriatic arthritis
- Baricitinib, JAK inhibitor in rheumatologic diseases
Frequently Asked Questions
How quickly does bimekizumab work in psoriasis?
The first visible improvement of plaques often appears after 2 to 4 weeks. The full clinical effect is assessed at week 16. In trials more than 80 percent of patients achieved a 90 percent improvement in PASI in this timeframe, and many became completely clear.
Why do I get more oral thrush?
IL 17A and IL 17F are crucial for defence against fungi, particularly Candida albicans. Dual blockade of both cytokines specifically dampens this defence, increasing the incidence of oral candidiasis. Regular oral hygiene, prompt topical antifungals and avoiding sugar keep the problem small.
Can I inject bimekizumab myself?
Yes. After training by your treating dermatologist or rheumatologist, the pre filled syringe or autoinjector can be used at home. Administration is subcutaneous into thigh, abdomen or upper arm; rotate the site regularly.
What happens in loss of efficacy?
About 5 to 10 percent of patients develop neutralising antibodies against bimekizumab during long term therapy that can reduce efficacy. When flares recur, the indication is reassessed; alternative biologics or JAK inhibitors are available. An individual therapy change is made by the specialist.
Sources
- EMA, Bimzelx (Bimekizumab) EPAR
- AWMF, S3 Guideline on Psoriasis and Psoriatic Arthritis
- Gelbe Liste, Bimekizumab active substance profile
- BfArM, Federal Institute for Drugs and Medical Devices
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