Rituximab

• Class: Anti-CD20 monoclonal antibody (chimeric IgG1)
• Mechanism: Binds CD20 on B-cells → induces cell lysis via complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC)

Indications (Oncology)

• Non-Hodgkin lymphoma (NHL) – CD20+ (e.g., DLBCL, follicular lymphoma)
• Chronic lymphocytic leukemia (CLL)
• Mantle cell lymphoma (often in combo regimens like R-CHOP or R-Bendamustine)
• Others: Autoimmune diseases (e.g., RA, ITP, GPA/MPA) — off-label or FDA-approved for some

Dosing

• IV, typically 375 mg/m² weekly × 4 for lymphomas; varies by indication and protocol

Key Side Effects

• Infusion reactions (fever, chills, hypotension) – especially first dose
• Infections – Hepatitis B reactivation (screen before use), PML (rare but serious)
• Cytopenias (neutropenia, thrombocytopenia)
• Cardiac events (arrhythmia, angina, especially in elderly)
• Tumor lysis syndrome (rare, high-burden disease)

Monitoring

• Before initiation:
  • Hepatitis B serology (HBsAg, anti-HBc)
  • CBC with differential
• During treatment:
  • Infusion reactions (monitor vital signs closely during and after infusion)
  • CBC periodically (for cytopenias)
  • Signs of infection or TLS
  • Cardiac status if high risk

Other Key Points

• Premedicate with acetaminophen + antihistamine ± corticosteroid
• Slow initial infusion rate; may increase gradually if tolerated
• Biosimilars available (e.g., Truxima, Ruxience)
• Often used in combination with chemotherapy (e.g., R-CHOP)