OCREVUS
Clinical safety rating: caution
Comprehensive clinical and safety monograph for OCREVUS (OCREVUS).
Ocrelizumab is a recombinant humanized monoclonal antibody that selectively targets CD20-positive B cells. It binds to the CD20 antigen expressed on pre-B cells, mature B cells, and memory B cells, but not on plasma cells or hematopoietic stem cells. Binding induces antibody-dependent cellular cytotoxicity and complement-mediated lysis, resulting in B-cell depletion.
| Metabolism | Ocrelizumab is a monoclonal antibody; it is catabolized into small peptides and amino acids via general protein degradation pathways. No specific metabolic enzymes are involved, and it does not rely on hepatic or renal pathways for clearance. |
| Excretion | Ocrelizumab is a humanized monoclonal antibody that is catabolized by general protein degradation pathways; it is not excreted renally or hepatically. Less than 1% is eliminated unchanged in urine. Biliary/fecal excretion is negligible as intact IgG. |
| Half-life | Terminal elimination half-life is approximately 26 days (range: 18–39 days) for the 600 mg intravenous dose. This supports every-6-month dosing for sustained B-cell depletion. |
| Protein binding | Ocrelizumab is an IgG1 monoclonal antibody; it does not bind to plasma proteins. Estimated protein binding is negligible (< 1%). |
| Volume of Distribution | Volume of distribution is approximately 2.78 L (range: 1.89–4.23 L), which corresponds to about 0.04 L/kg for a 70 kg adult. This low Vd indicates distribution primarily in the vascular and interstitial spaces. |
| Bioavailability | Ocrelizumab is only administered intravenously; bioavailability is 100% by the IV route. Subcutaneous or oral routes are not approved; bioavailability via these routes is unknown. |
| Onset of Action | For intravenous administration, B-cell depletion in peripheral blood occurs within 2 weeks of the first dose. Clinical onset of effect in relapsing multiple sclerosis may be seen as early as 4 weeks. |
| Duration of Action | Duration of B-cell suppression is sustained for at least 6 months. After treatment cessation, B-cell counts generally recover over 6–12 months but may remain low beyond 18 months in some patients. |
300 mg intravenous infusion followed 2 weeks later by a second 300 mg intravenous infusion; then 600 mg intravenous infusion every 6 months.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment; not studied in severe renal impairment (CrCl <15 mL/min). |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B); not studied in severe hepatic impairment (Child-Pugh C). |
| Pediatric use | Safety and efficacy in pediatric patients (<18 years) have not been established; no dosage recommendation. |
| Geriatric use | No specific dose adjustment required based on age; consider comorbidities and concomitant medications. Clinical studies included patients up to age 65, limited data in >65 years. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for OCREVUS (OCREVUS).
| Breastfeeding | It is not known whether ocrelizumab is excreted in human milk. Human IgG is present in breast milk, and limited data suggest that monoclonal antibodies are transferred in small amounts. The M/P ratio is not established for ocrelizumab. Caution should be exercised; the decision to breastfeed should consider the mother's need for therapy, the potential for drug excretion, and the infant's immune status. |
| Teratogenic Risk | Ocrevus (ocrelizumab) is a humanized monoclonal antibody that depletes CD20-positive B cells. IgG antibodies cross the placenta, especially in the third trimester. There are no adequate and well-controlled studies in pregnant women. In animal studies, ocrelizumab was not teratogenic but caused B-cell depletion in offspring. Use is not recommended unless the benefit outweighs the risk. Based on limited human data, there is no known structural teratogenicity; however, the potential for B-cell depletion and immunosuppression in the fetus, particularly if administered during the second and third trimesters, exists. |
■ FDA Black Box Warning
None
| Serious Effects |
["Active hepatitis B virus infection","History of life-threatening infusion reaction to ocrelizumab","Severe, active infections (e.g., tuberculosis, sepsis)"]
| Precautions | ["Infusion reactions: May require premedication; monitor during infusion","Infections: Increased risk, including herpes zoster and respiratory tract infections; screen for hepatitis B virus before initiation","Progressive multifocal leukoencephalopathy (PML): Rare but serious; discontinue if suspected","Immunoglobulin levels: Monitor; low IgG associated with increased infection risk","Malignancies: Possible increased risk, particularly breast cancer","Fetal harm: Avoid in pregnancy; women of childbearing potential should use contraception"] |
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| Fetal Monitoring | For infants exposed in utero, monitor for B-cell count and immune function; assess for infections and evaluate response to vaccinations, particularly live vaccines. In the mother, monitor for infections and infusion-related reactions. No specific fetal monitoring beyond routine prenatal care is recommended. |
| Fertility Effects | No formal fertility studies in humans. Animal studies at doses up to 100 mg/kg showed no adverse effects on male or female fertility. Based on its mechanism (B-cell depletion), fertility is unlikely to be affected, but data are insufficient to rule out potential impact. |