Brodalumab

• Plaque Psoriasis
• Moderate to Severe Psoriasis
• Biologic Psoriasis Treatment
• IL-17 Pathway Blockade

Brodalumab (Siliq) is a fully human IgG2 monoclonal antibody that blocks the interleukin-17 receptor A (IL-17RA), used for adult patients with moderate-to-severe plaque psoriasis who have failed or lost response to other systemic therapies. Unlike most biologics in the IL-17 family, brodalumab targets the receptor itself, providing broad blockade of multiple IL-17 cytokines — but it carries a boxed warning for suicidal ideation and is dispensed only through a restricted REMS program, which has limited its uptake in routine dermatology practice. When used appropriately and with rigorous mental-health monitoring, it produces some of the highest rates of complete skin clearance seen with any biologic.

Mechanism of Action

Brodalumab binds with high affinity to IL-17RA, the shared receptor subunit used by multiple IL-17 family cytokines. By blocking the receptor rather than a single ligand, brodalumab simultaneously inhibits signaling from IL-17A, IL-17F, the IL-17A/F heterodimer, IL-17C, and IL-17E (also known as IL-25). This is mechanistically broader than IL-17A-only antibodies such as secukinumab and ixekizumab, and may explain why some patients who lose response to IL-17A blockade can recapture clearance with brodalumab — alternative IL-17 family cytokines are still able to signal through the receptor when only IL-17A is blocked, but receptor-level blockade closes that escape route.

The IL-17 axis drives the keratinocyte hyperproliferation, neutrophilic infiltration, and chronic inflammation characteristic of plaque psoriasis. Comprehensive blockade produces rapid clearing — many patients achieve PASI 90 or PASI 100 within 12 weeks of initiation, and a substantial fraction reach completely clear or almost-clear skin (Investigator Global Assessment 0/1) by week 16. Time to first response is rapid, with measurable improvement often visible within 2–4 weeks. The National Library of Medicine maintains a current overview of the IL-17 pathway in immune-mediated disease, and the American Academy of Dermatology psoriasis resource reviews how this mechanism has reshaped treatment goals from "manageable" to "clear."

The origin of the boxed warning for suicidal ideation remains incompletely understood. Whether brodalumab causes mood effects through some interaction with IL-17 signaling in the central nervous system, whether it reflects the high baseline rate of depression in moderate-to-severe psoriasis (well-established to roughly double the population baseline), or whether it represents a chance signal in trial data remains debated. Regardless of mechanism, the FDA mandates a structured monitoring program.

Clinical Use

Brodalumab is reserved for moderate-to-severe plaque psoriasis in adults who are candidates for systemic therapy or phototherapy and have failed at least one other systemic agent. In contemporary dermatology practice it is rarely first-line among biologics because of the REMS requirement and the boxed warning; clinicians more often start with an IL-23 inhibitor such as guselkumab, risankizumab, or tildrakizumab; an IL-17A blocker like secukinumab or ixekizumab; or a TNF inhibitor such as adalimumab, etanercept, infliximab, certolizumab, or golimumab. Brodalumab earns a place when other biologics fail, as its receptor-level blockade can recapture response in patients with secondary loss of efficacy.

It is not approved for psoriatic arthritis, in contrast to several IL-17A inhibitors that hold dual indications. Patients with concurrent inflammatory arthritis where joint disease dominates the clinical picture may be better served by a different agent that addresses both skin and joints. Patients with concurrent inflammatory bowel disease should generally avoid IL-17 receptor blockade because Crohn disease may flare or unmask. Oral systemic alternatives for patients who prefer to avoid injections include methotrexate, apremilast, deucravacitinib, and the older systemic agents. JAK inhibitors such as tofacitinib and upadacitinib have a place in psoriatic arthritis but more limited utility in plaque psoriasis alone.

For topical therapy or limited disease, hydrocortisone, other topical corticosteroids, and vitamin D analogs remain mainstays. Phototherapy is an effective non-pharmacologic option in select patients.

How to Take It

Brodalumab is a 210 mg subcutaneous injection given at weeks 0, 1, and 2 (loading doses), then every 2 weeks. Patients self-administer after training, rotating sites between thigh, abdomen (avoiding a 2-inch zone around the navel), and upper arm. Avoid injecting into actively inflamed psoriatic plaques, areas of skin that are tender, bruised, red, or hard, or sites with stretch marks or scars. The prefilled syringe should be removed from the refrigerator 30 minutes before injection to allow it to come to room temperature, which substantially reduces injection-site discomfort. Never shake the syringe, never use it if the solution looks cloudy or contains visible particles, and never use a syringe past its expiration date.

Because brodalumab is dispensed under a REMS program, patients must sign a Patient-Prescriber Agreement Form acknowledging the risk of suicidal ideation and behavior, and must commit to seeking immediate help if such thoughts develop. Prescribers must be REMS-certified and pharmacies enrolled. Family members and household contacts should be informed about the warning signs of worsening mood. Patients should be instructed to stop the drug and contact the prescriber immediately for any new or worsening depressive symptoms or thoughts of self-harm.

If clinical response is inadequate by week 12–16, discontinuation should be considered rather than dose escalation; the drug does not have an approved higher dosing tier and lack of response by this timepoint usually predicts longer-term failure. Patients who initially respond and then lose response (secondary failure) should have antibody formation considered as one possible cause, though anti-drug antibodies are less common with fully human biologics than with chimeric or humanized agents.

Keep the medication refrigerated between 36 F and 46 F (2–8 C); do not freeze. Travel requires a cooler with ice packs and accommodations for in-flight refrigeration on long trips.

Monitoring and Follow-Up

Before starting therapy, screen for latent tuberculosis with an interferon-gamma release assay or PPD, hepatitis B and C serologies (HBsAg, anti-HBc, anti-HBs, anti-HCV), and confirm immunization status with particular attention to MMR, varicella, and zoster vaccines. Live vaccines must be completed before initiation and avoided during therapy. Periodic CBC monitoring is reasonable to detect neutropenia, and any new gastrointestinal symptoms — abdominal pain, persistent diarrhea, blood in the stool — should prompt evaluation for inflammatory bowel disease. The understanding blood work article explains what these baseline labs measure and how patterns are interpreted.

Mental health screening — using validated instruments such as the PHQ-9 — should occur at every visit. Skin examinations document treatment response (PASI score, body-surface-area involvement, Investigator Global Assessment) at routine intervals. Photography of representative plaques at baseline and at 4-month intervals is helpful for tracking. The article on recognizing burnout and exhaustion is a useful adjunct because chronic disease burden affects mood independently of medication risk, and our piece on chronic stress and physical illness reviews how psychological factors and immune-mediated skin disease interact bidirectionally.

Annual skin cancer screening is appropriate given long-term immune modulation, particularly for patients in sun-rich climates — see our skin cancer screening guidance. Stay up to date on vaccinations including influenza, COVID-19, pneumococcal, and shingles (using the inactivated recombinant zoster vaccine, not the live attenuated form).

Special Populations

There are no controlled data in pregnant patients; IgG2 antibodies cross the placenta in increasing amounts during the second and third trimesters, so neonatal immune effects are theoretically possible. Decisions in pregnancy should weigh disease severity against limited safety data, and live vaccines should be deferred in infants with significant in-utero exposure. The drug has not been studied in patients under age 18. Elderly patients (over 75) were limited in trials, but no specific dose adjustment is recommended; close attention to infection risk and mood is warranted. Renal and hepatic impairment do not require dose modification because monoclonal antibodies are cleared via reticuloendothelial proteolysis rather than hepatic or renal pathways.

Patients with active Crohn disease or ulcerative colitis should not use brodalumab; those with a personal or family history of inflammatory bowel disease warrant careful consideration of alternatives such as IL-23 inhibitors, which have a more favorable IBD safety profile and may even improve concurrent IBD. Patients with a personal or family history of completed suicide, severe depression, or active suicidal ideation should generally not receive brodalumab; alternative biologics carry no comparable warning.

When to Contact Your Doctor

Seek immediate help for: any new or worsening thoughts of self-harm or suicide, signs of serious infection (high fever, persistent cough, hypotension, severe localized infection); abdominal pain with bloody diarrhea suggesting Crohn flare; or signs of allergic reaction (facial swelling, hives, difficulty breathing). Report any new persistent skin lesion that does not match the patient's usual psoriasis pattern. The FDA prescribing information details the suicidal ideation risk profile and full safety warnings, and MedlinePlus provides patient-friendly information.

If you have questions about brodalumab or your psoriasis treatment plan, our team at Zimmer Medical Group can help — contact us or schedule a visit.