Post-Rituximab Management for ITP
After completing four weekly rituximab infusions at 375 mg/m², monitor platelet counts weekly for the first 6 months and wait up to 8 weeks before declaring treatment failure, then transition to a thrombopoietin-receptor agonist if no response occurs or if relapse develops. 1
Monitoring Strategy
- Check platelet counts weekly for the first 6 months, with particular attention to the 1–8 week window when most responses occur 1
- The median time to platelet response is 14 weeks (range 4–32 weeks), so continue observation for at least 8 weeks before deeming rituximab ineffective 1, 2
- Monitor baseline and periodic immunoglobulin levels to detect hypogammaglobulinemia, especially if considering additional rituximab courses 1
- Assess ADAMTS13 activity at baseline and periodically, as repeated rituximab exposure markedly raises hypogammaglobulinemia risk 1
Response Assessment
- Define response as: complete response (platelet ≥100 × 10⁹/L), partial response (platelet 50–99 × 10⁹/L), or minimal response (platelet 30–49 × 10⁹/L) 1
- Approximately 60–70% of patients show initial response, but half will eventually relapse 3
- Only 30% maintain sustained remission at 5 years after one rituximab course 1, 3
- **Female patients and those with disease duration <2 years** have markedly better outcomes, with 79% achieving durable remission (>48 months) versus 0–21% in other groups 1, 4
Management of Non-Responders or Relapse
If rituximab fails or relapse occurs after initial response, transition to a thrombopoietin-receptor agonist (romiplostim or eltrombopag) as the next second-line option. 1
- Romiplostim achieves 79–88% response rates 1
- Eltrombopag achieves 70–81% response rates 1
- Retreatment with rituximab is an alternative option if initial response was sustained, showing similar or higher magnitude and duration of response in most patients 3
Safety Monitoring
- Avoid prolonged corticosteroid use while awaiting rituximab response, as this increases bleeding risk during tapering and contributes to weight gain, diabetes, and osteoporosis 1
- Monitor for rare but serious adverse events: progressive multifocal leukoencephalopathy, hepatitis B reactivation, and severe mucocutaneous reactions 1, 5
- Do not administer multiple rituximab courses without prior immunoglobulin monitoring, as repeated dosing substantially raises hypogammaglobulinemia likelihood 1
- Approximately 14 patients per cohort may develop hypogammaglobulinemia, with half experiencing increased frequency of minor infections; most recover IgG levels over time 4
Key Pitfalls to Avoid
- Do not declare treatment failure before 8 weeks, as responses can occur late (median 14 weeks, up to 32 weeks) 1, 2
- Do not continue steroids indefinitely while waiting for rituximab response—this worsens outcomes 1
- Do not repeat rituximab without checking immunoglobulin levels first—hypogammaglobulinemia risk increases substantially with repeated courses 1