II. Indications: Leukemia and Lymphoma
- Non-Hodgkin's Lymphoma
 - Large B cell Lymphoma
 - Burkitt Lymphoma
 - 
                          Follicular Lymphoma
                          
- Obinutuzumab
 
 - 
                          Chronic Lymphocytic Leukemia
                          
- Rituximab
 - Ofatumumab
 
 - Acute Mature B Cell Leukemia
 
III. Indications: Non-Oncology
- Refractory Rheumatoid Arthritis
 - Granulomatosis with Polyangiitis (formerly known as Wegener's Granulomatosis)
 - 
                          Multiple Sclerosis
                          
- Ofatumumab
 - Ocrelizumab (Ocrevus)
 - Delgado (2024) J Neurol 271(4):1515-35 +PMID: 37906325 [PubMed]
 
 
IV. Contraindications
- Active Hepatitis BVirus Infection
- Screen before starting regimen
 
 
V. Mechanism
- See Monoclonal Antibody-Mediated Chemotherapy
 - CD20 Antigens
- CD20 Antigens are phosphoproteins found only on the surface of B-Cells including Leukemia, Lymphoma (but not B-Cell precursors)
 - Regulate transmembrane Calcium conductance
 - Plays a role in B-Cell Activation and proliferation, as well as complement-dependent cytotoxicity
 
 - Anti-CD20 Monoclonal Antibody
- Recombinant human Monoclonal Antibody directed against the CD20 Antigen cell surface marker
 - Bind CD20 and triggers a cytotoxic immune response, depleting CD20 positive B Cells
 
 
VI. Medications: Anti-CD20
- 
                          Rituximab (Rituxan)
- See Rituximab
 - Used in Non-Hodgkin's Lymphoma (as well as several other Lymphomas and Leukemias)
 - Also used in Refractory Rheumatoid Arthritis, Granulomatosis with Polyangiitis
 - Risk of severe infusion reactions and severe mucocutaneous reactions
 - Also risk of PML, Tumor Lysis Syndrome, Hepatitis B reactivation and Bowel Obstruction and perforation
 - Also risk of Acute Kidney Injury, Cardiac Arrhythmia and severe cytopenia
 
 - Ofatumumab (Arzerra, Kesimpta)
- Used in Chronic Lymphocytic Leukemia (Arzerra) and Multiple Sclerosis (Kesimpta)
 - Risk of severe infusion reactions, Severe infections, Hepatitis B reactivation
 
 - Obinutuzumab (Gazyva)
- Used in CLL, Follicular Lymphoma
 - Risk of Hepatitis B reactivation, PML, DIC, Tumor Lysis Syndrome, infusion reactions, severe infections, cytopenias,
 
 - Ocrelizumab (Ocrevus)
- Indicated for Multiple Sclerosis (relapsing, and primary progressive)
- First-line only in primary progresive MS (only one FDA approved in primary progressive MS)
 
 - Pretreat doses with Methylprednisolone and Diphenhydramine (or other Antihistamine) 30 to 60 minutes before dose
 - Adults with MS
- Load: 300 mg IV infusion over 3.5 hours for 2 doses, 2 weeks apart
 - Maintenance: 600 mg IV infusion over 3.5 hours every 6 months
 
 
 - Indicated for Multiple Sclerosis (relapsing, and primary progressive)
 
VII. Medications: Anti-CD20 with Cytotoxic Conjugates
- Ibritumomab tiuxetan (Zevalin)
- Used for Non-Hodgkin's Lymphoma
 - Risk of severe infusion reactions, cytopenias and secondary malignancies
 - Conjugate of CD20 Monoclonal Antibody (Ibritumomab) and a radioisotope chelation site (tiuxetan)
- Tiuxetan is bound to Iridium-111 or yttrium Y-90
 - Delivers cytotoxic dose of radiation to B Cells with CD20 cell surface marker
 
 
 - Tositumomab-Iodine 131 (Bexxar)
- Used for Non-Hodgkin's Lymphoma
 - Risk of severe infusion reactions, cytopenia, secondary malignancy, Hypothyroidism
 - Conjugate of CD20 Monoclonal Antibody (Tositumomab) and a radioisotope, Iodine-131
- Delivers cytotoxic dose of radiation to B Cells with CD20 cell surface marker
 
 
 
VIII. Dosing
- See other references for disease specific dosing protocols
 
IX. Adverse Effects
- Severe infusion reactions including Anaphylaxis (Rituximab, Ofatumumab, Ibritumomab, Obinutuzumab, Tositumomab)
 - Severe mucocutaneous syndrome (Rituximab, Ibritumomab)
 - Progressive Multifocal Leukoencephalopathy (Rituximab, Ofatumumab, Obinutuzumab)
 - Tumor Lysis Syndrome (Rituximab, Obinutuzumab)
 - Hepatitis B reactivation (Rituximab, Ofatumumab, Obinutuzumab)
 - Acute Kidney Injury (Rituximab)
 - Cardiac Arrhythmia (Rituximab)
 - Severe cytopenia (Rituximab, Ofatumumab, Ibritumomab, Obinutuzumab, Tositumomab)
 - Bowel Obstruction and perforation (Rituximab, Ofatumumab)
 - Severe infections (Rituximab, Obinutuzumab)
 - Hypothyroidism (Tositumomab-I131)
 - Secondary malignancy (Ibritumomab-tiuxetan, Tositumomab-I131)
 
X. Safety
- Avoid in Lactation
 - Avoid in pregnancy (all trimesters, Pregnancy category X)
- Use reliable Contraception
 
 
XI. Drug Interactions
- 
                          Vaccines
- Give non-Live Vaccines at least 2 weeks prior to dosing
 - Hold CD20 Monoclonal Antibody for 6 months before and 4-6 weeks after Live Vaccines
- Ideally, give Live Attenuated Vaccines at least 6 weeks before starting CD20 Monoclonal Antibodies