FOSTAMATINIB TAB
Clinical Criteria Summary
Exclusion Criteria
- Care not provided by a VA or VA purchased care hematology provider
- History of non-adherence with oral medication, follow-up appointments, or laboratory visits
- Unable to comply with dosing instructions
- Chronic therapy with a strong CYP3A4 inducer that cannot be interrupted
- Has not received prior therapy to increase platelet counts
- Thrombocytopenia secondary to bone marrow suppressive anti-cancer therapy, antibiotics, or other medication
- Thrombocytopenia secondary to chronic liver disease
- Pregnancy and/or breastfeeding
Inclusion Criteria
- Documented diagnosis of chronic ITP per American Society of Hematology (ASH) guidelines: diagnosis based upon history, PE, CBC and exam of peripheral smear
- Platelet count < 30,000 mm3
- Inadequate response or contraindication to at least 2 prior treatment categories: splenectomy; rituximab; thrombopoietin agonists (eltrombopag or romiplostim); danazol or immune suppressants (azathioprine, cyclosporine or mycophenolate mofetil)
- For women of childbearing potential: Pregnancy excluded prior to receiving fostamatinib; provided contraceptive counseling on potential risks vs. benefits if patient were to become pregnant; awareness that fostamatinib may affect female fertility
Dosage and Administration
- 100 mg taken orally twice daily with or without food
- After 4 weeks, if platelet count has not increased to at least 50 x 109/L, increase dose to 150 mg twice daily
- Dosing regimen should be interrupted, reduced, or discontinued to manage adverse effect profile (HTN, hepatotoxicity, diarrhea, neutropenia)
- Concomitant use with a strong CYP3A4 inhibitor increases exposure; monitor for toxicity as doses may need adjustment
Monitoring Requirements
- Baseline labs prior to initiation: CBC with differential (ANC, platelets), LFTs (AST, ALT, bilirubin), baseline stable BP
- During treatment: CBC with differential monthly, LFTs monthly, BP every 2 weeks until stabilized dose then monthly thereafter, severity and duration of diarrhea, fever and signs/symptoms of infection, unusual bleeding and/or bruising
Adverse Effects and Management
- Hypertension (all grades 28%; > grade 3: 2%): Monitor; management may require addition and/or adjustment of antihypertensive therapies
- Hepatotoxicity: Monitor; manage by fostamatinib dose adjustment or discontinuation
- Diarrhea: Monitor; manage with supportive measures and dose adjustment
- Neutropenia: Monitor for infection; manage with supportive measures and dose adjustment
Discontinuation Recommendations
- Non-compliance with therapy, laboratory, or follow-up requests
- Discontinue after 12 weeks of therapy if platelets have not increased to a level sufficient to avoid clinically important bleeding