Tocilizumab

Trade Names: Actemra

Drug Class: Biologic DMARD, IL-6 receptor antagonist

Preparations: IV: 80 mg/4 mL, 200 mg/10 mL, 400 mg/20mL
Subcutaneous injection: 162 mg/0.9 mL prefilled syringe

Dose: Adults IV: initially 4 mg/kg every 4 weeks, dose  may be increased to 8 mg/kg depending on response, maximum dose is 800 mg.
Subcutaneous injection:  less than 100 kg  – 162 mg every other week, may increase to every week depending on response; 100 kg or heavier – 162 mg every week. Adjust dose according to monitoring of LFTs, platelets and absolute neutrophil count (ANC).

If AST/ALT increased >1  up to 3x normal: Check other drugs; for persistent increases reduce to  low dose (i.e.,  4 mg/kg (IV)  or reduce frequency of subcutaneous injection to every 2 weeks)  or interrupt therapy till AST/ALT normalized.
If AST/ALT  increased 3-5x normal: Confirm with a repeat  test and interrupt therapy till below 3x normal and then restart at low  dose  (as  above).  If enzymes do not fall below 3x normal discontinue tocilizumab.
If AST/ALT increased more than 5x normal:  Discontinue tocilizumab.

If platelet count 50,000-100,000/mm3 or ANC 500-1000/mm3: Interrupt therapy till platelets more than 100,000/mm3 or ANC more than 1,000/mm3 and then restart at  low dose.
If platelet count less than 50,000/mm3 or ANC less than 500/mm3: Discontinue tocilizumab.

Indications: Active RA with inadequate response to 1 or more DMARDs, systemic and polyarticular juvenile idiopathic arthritis

Mechanism of Action: Binds to IL-6 receptors and blocks the effects of the cytokine

Contraindications: Hypersensitivity, active infection, do not initiate if ANC less than 2000/mm3, or platelets less than 100,000/mm3, or AST or ALT more than 1.5x upper limit of normal. Do not use with TNF-antagonists, biologics, tofacitinib, abatacept. Do not use if hepatic impairment. Avoid live virus vaccines and BCG.

Precautions: Increased risk of serious infections including TB and fungal. Exclude latent or active TB with a skin test or TB blood test (interferon-gamma release assays or IGRA). Caution in debilitated or high risk of infection. Exclude active hepatitis B infection or carriage.  Rare  CNS demyelination and gastrointestinal perforation – caution if preexisting risk.  IV infusion should be performed in a center able to deal with anaphylaxis.

Monitoring: Check CBC  with diff, LFTs, cholesterol at baseline and exclude TB. Check CBC , platelets, ANC, AST, ALT   every 4-8 weeks for 6 months after initiation and then every 2-3 months. Lipid panel after 4-8 weeks and then every 6  months. After therapy started, additional TB testing may be indicated for individuals likely to have exposure to TB.

Pregnancy Risk: C

Adverse Effects
Common: Increased cholesterol, increased liver enzymes, infusion reactions (IV), injection site reactions (subcutaneous), hypertension, headache, upper respiratory tract infections
Less common: Allergy, rash, serious infection (bacterial, viral (e.g., zoster) and also atypical and opportunistic infections), decrease in neutrophil or and platelet count
Rare: Neutropenia, thrombocytopenia, anaphylaxis, gastrointestinal perforation, demyelinating CNS disease, hepatitis, vasculitis

Drug Interactions
Live virus vaccines and BCG: Avoid
Other biologics and potent immunosuppressants: Avoid, increased risk of infection

Patient Instructions: Avoid live virus vaccines. Avoid pregnancy. Stop injections if have an infection

Comments:  The 8 mg/kg IV dose  was generally more effective than the 4 mg/kg dose in clinical trials. Doses lower than 4 mg/kg IV are not recommended  because of increased immunogenicity and decreased efficacy. Tocilizumab is effective for RA  as monotherapy but generally responses  have been greater  when combined with methotrexate. In a monotherapy trial  tocilizumab 8 mg/kg IV every 4 weeks was more effective than adalimumab 40 mg subQ every 2 weeks.  IL6  drives CRP production, therefore  CRP decreases dramatically.  The clinical significance of the increase in cholesterol as regards cardiovascular risk is not known; treat  increased cholesterol according to current guidelines. Limited information on long-term risks (e.g. malignancy). Limited information in other  conditions – case series or case reports suggest possible efficacy in giant cell arteritis, polymyalgia rheumatica, Takayasu’s arteritis, adult onset Still’s disease, Castleman’s disease and other conditions.

Clinical Pharmacology: Half-life is 6-13 days. Biologic agents are not metabolized and have few drug interactions.

Adapted from: RheumaKnowledgy