Maintenance Laboratory Monitoring for Ocrevus (Ocrelizumab)
Pre-Treatment Screening Requirements
Before initiating Ocrevus, hepatitis B virus screening and quantitative serum immunoglobulin levels are mandatory. 1
Routine Maintenance Laboratory Monitoring
For patients on Ocrevus, perform complete blood count (CBC) with differential and comprehensive metabolic panel (CMP) at baseline and at 2- to 4-month intervals throughout treatment. 2 This monitoring schedule is based on the rituximab (another anti-CD20 antibody) monitoring recommendations from rheumatology guidelines, which apply to ocrelizumab given their similar mechanisms of action.
Specific Laboratory Tests and Intervals:
- CBC with differential: Monitor at baseline and every 2-4 months to detect cytopenias 2
- Immunoglobulin levels: Monitor at baseline, during treatment, and after discontinuation until B-cell repletion, especially when recurrent serious infections are suspected 1
- Liver function tests: While not explicitly mandated in the FDA label, periodic monitoring is prudent given hepatotoxicity risks with immunosuppressive therapies 2
Lymphocyte Monitoring Considerations
Absolute lymphocyte count (ALC) monitoring every 3 months is reasonable, though not officially mandated by FDA labeling. 2 While ALC reduction is an expected pharmacodynamic effect of ocrelizumab and changes in ALC are not associated with efficacy or safety outcomes, periodic monitoring helps identify significant lymphopenia (<0.2 × 10⁹/L) 2. In clinical trials, <2% of patients developed ALC <0.2 × 10⁹/L, and most returned to normal levels while remaining on treatment 2.
Infection Surveillance
Monitor patients closely for signs of infection at each visit, as serious and life-threatening infections have occurred with ocrelizumab. 1 The serious infection rate in clinical trials ranged from 18.7 to 28.8 events per 100 patient-years depending on background therapy 3.
- Hepatitis B reactivation screening: Required before initiation 2
- Tuberculosis screening: Should be performed before starting therapy 2
- Progressive multifocal leukoencephalopathy (PML) vigilance: Withhold treatment at first sign or symptom suggestive of PML 1
Special Monitoring Situations
If prolonged hypogammaglobulinemia develops and requires intravenous immunoglobulin treatment, consider discontinuing Ocrevus. 1 Similarly, discontinue in patients with serious opportunistic or recurrent serious infections 1.
For patients with diabetes or history of uveitis/macular edema, perform regular ophthalmologic evaluations during treatment. 2 While macular edema incidence is low (≤0.6%), most cases occurred in patients with pre-existing risk factors 2.
Clinical Monitoring Beyond Laboratory Tests
- Monitor during and after each infusion: At least 1 hour after initial injection and at least 15 minutes after subsequent injections 1
- Infusion/injection reactions: Most common adverse reaction (49% with subcutaneous formulation) 1, 4
- B-cell repletion: Median time for B-cell counts to return to baseline or lower limit of normal is 72 weeks (range 27-175 weeks) after last dose 1
Common Pitfalls to Avoid
Do not administer live or live-attenuated vaccines during Ocrevus treatment or after discontinuation until B-cell repletion occurs. 1 Delay Ocrevus administration in patients with active infection until the infection resolves 1.
Do not ignore new gastrointestinal symptoms, as immune-mediated colitis has been reported in postmarketing surveillance; evaluate promptly if colitis is suspected 1.