Introduction
Truxima (rituximab-abbs) is a biosimilar to Rituxan (rituximab), approved by the FDA in November 2018. It is a CD20-directed cytolytic antibody indicated for the treatment of various hematologic malignancies, autoimmune disorders, and other conditions. As a biosimilar, Truxima has demonstrated no clinically meaningful differences from the reference product in terms of safety, purity, and potency.
Mechanism of Action
Truxima is a monoclonal antibody that specifically binds to the CD20 antigen expressed on the surface of pre-B and mature B lymphocytes. Upon binding, it mediates B-cell lysis through three primary mechanisms:
- Complement-dependent cytotoxicity (CDC)
- Antibody-dependent cellular cytotoxicity (ADCC)
- Direct induction of apoptosis (programmed cell death)
This results in depletion of circulating B-cells, which play key roles in various autoimmune and malignant processes.
Indications
Truxima is FDA-approved for:
- Non-Hodgkin's Lymphoma (NHL): Relapsed or refractory, low-grade or follicular, CD20-positive B-cell NHL
- Chronic Lymphocytic Leukemia (CLL): In combination with fludarabine and cyclophosphamide for previously untreated and previously treated CD20-positive CLL
- Granulomatosis with Polyangiitis (GPA) and Microscopic Polyangiitis (MPA): In combination with glucocorticoids
- Pemphigus Vulgaris: Moderate to severe disease
Dosage and Administration
NHL: 375 mg/m² IV weekly for 4 or 8 doses (depending on regimen) CLL: 375 mg/m² IV first cycle, then 500 mg/m² IV for subsequent cycles (in combination with chemotherapy) Autoimmune indications: 375 mg/m² IV weekly for 4 weeks (GPA/MPA) or 1000 mg IV on days 1 and 15, then 500 mg at months 6 and 12 (pemphigus) Administration:- Premedicate with methylprednisolone 100 mg IV (or equivalent) and diphenhydramine and acetaminophen
- Initial infusion: Start at 50 mg/hr, gradually increase by 50 mg/hr increments every 30 minutes to maximum 400 mg/hr
- Subsequent infusions: Start at 100 mg/hr, increase by 100 mg/hr increments every 30 minutes to maximum 400 mg/hr
- Renal impairment: No dosage adjustment necessary
- Hepatic impairment: No specific recommendations
- Elderly: No dosage adjustment necessary
Pharmacokinetics
Absorption: Administered intravenously only; complete bioavailability Distribution: Volume of distribution approximately 3.1 L; binds to CD20-positive lymphocytes Metabolism: Primarily via proteolytic catabolism Elimination: Half-life approximately 22 days (range 6-52 days); clearance decreases with repeated dosing due to B-cell depletionContraindications
- Known hypersensitivity to rituximab products or murine proteins
- Active hepatitis B infection
- Severe, active infection
Warnings and Precautions
Infusion Reactions: Can be severe (including fatal outcomes). Monitor closely during and for several hours post-infusion Severe Mucocutaneous Reactions: Stevens-Johnson syndrome, toxic epidermal necrolysis, and other severe reactions have been reported Hepatitis B Reactivation: Can result in fulminant hepatitis, hepatic failure, and death Progressive Multifocal Leukoencephalopathy (PML): JC virus infection resulting in PML, which is usually fatal Tumor Lysis Syndrome: Risk highest in patients with high tumor burden Infections: Serious bacterial, fungal, and new or reactivated viral infections Cardiovascular Events: Arrhythmias, angina, and cardiac arrest have occurred Hypogammaglobulinemia: Can occur with long-term useDrug Interactions
- Live vaccines: Avoid administration during and after treatment
- Cisplatin: Increased risk of nephrotoxicity
- Immunosuppressants: Additive immunosuppression
- Antihypertensives: Increased risk of hypotension during infusion
Adverse Effects
Most Common (≥25%):- Infusion reactions (fever, chills, rigors)
- Infections
- Asthenia
- Nausea
- Thrombocytopenia
- Severe infusion reactions
- Hepatitis B reactivation
- PML
- Severe mucocutaneous reactions
- Cardiac events
- Bowel obstruction and perforation
Monitoring Parameters
Prior to treatment:- Hepatitis B screening (HBsAg, anti-HBc, anti-HBs)
- CBC with differential
- Renal and hepatic function
- Cardiac assessment in high-risk patients
- Vital signs every 30 minutes during infusion
- Monitor for infusion reactions
- CBC regularly
- Signs of infection
- Monitor for delayed neutropenia
- Hepatitis B reactivation for several months
- Immunoglobulin levels with prolonged therapy
Patient Education
- Report any signs of infection (fever, chills, cough)
- Immediately report skin reactions or mouth sores
- Avoid live vaccines during and after treatment
- Inform all healthcare providers about Truxima treatment
- Report any neurological symptoms
- Use effective contraception during and for 12 months after treatment
- Understand the risk of hepatitis B reactivation
References
1. FDA Prescribing Information: Truxima (rituximab-abbs) injection 2. Cohen SB, et al. Arthritis Rheumatol. 2017;69(7):1386-1403 3. Salles G, et al. Blood. 2017;129(12):1629-1635 4. US National Library of Medicine. ClinicalTrials.gov 5. Biosimilars Council. "Understanding Biosimilars" 2022 6. American Society of Clinical Oncology guidelines for biosimilar use 7. European Medicines Agency assessment reports 8. Journal of Clinical Oncology reviews on rituximab biosimilars
Note: This information is intended for educational purposes only and should not replace professional medical advice. Always consult with a qualified healthcare provider for personalized medical guidance.