How to manage a patient with Immune Thrombocytopenic Purpura (ITP) and Acute Myeloid Leukemia (AML)?

Management of Immune Thrombocytopenic Purpura (ITP) in Patients with Acute Myeloid Leukemia (AML)

For patients with concurrent ITP and AML, treatment should prioritize the AML with appropriate chemotherapy while managing ITP with corticosteroids or intravenous immunoglobulin (IVIg) to maintain safe platelet counts during induction therapy. 1

Initial Assessment and Considerations

• Determine if thrombocytopenia is primarily due to AML bone marrow infiltration or ITP autoimmune mechanisms, as this distinction guides treatment approach 1
• Evaluate bleeding risk based on platelet count, with counts <20-30 × 10⁹/L indicating significant risk requiring immediate intervention 1, 2
• Assess for signs of active bleeding, which would necessitate more aggressive platelet support 1
• Consider central nervous system (CNS) involvement in AML patients, but avoid lumbar puncture if platelet counts are critically low due to ITP 1

Treatment Algorithm for Concurrent ITP and AML

First-line Management:

• For AML: Initiate appropriate induction chemotherapy based on AML subtype, cytogenetics, and molecular profile 1
• For ITP during AML treatment:
  • Start corticosteroids (prednisone 1 mg/kg/day or equivalent) as first-line therapy for ITP 1
  • Consider IVIg (1 g/kg as one-time dose, repeatable if necessary) for rapid platelet increase before invasive procedures or if corticosteroids are contraindicated 1
  • Avoid anti-D immunoglobulin in AML patients due to potential hemolysis complications in already compromised bone marrow function 1

Supportive Care Measures:

• Maintain higher platelet transfusion thresholds (≥10,000/mcL) compared to typical AML management 1
• Use leukocyte-depleted and irradiated blood products for all transfusions 1
• Monitor for tumor lysis syndrome with appropriate prophylaxis (hydration, allopurinol, or rasburicase) 1
• Avoid invasive procedures including central venous catheterization when platelet counts are critically low 1

Management of Refractory ITP in AML Context:

• For ITP patients not responding to first-line therapy during AML treatment:
  • Consider thrombopoietin receptor agonists (TPO-RAs) such as romiplostim at an initial dose of 1 mcg/kg subcutaneously once weekly, with dose adjustments to maintain platelet count ≥50 × 10⁹/L 3, 4
  • Maximum romiplostim dose should not exceed 10 mcg/kg per week 3, 4
  • Monitor for potential bone marrow effects, as TPO-RAs have been associated with increased blast counts in myelodysplastic syndromes, raising concerns about potential impact on AML 3
  • Rituximab may be considered for patients who have failed corticosteroids and IVIg, but timing must be coordinated with AML chemotherapy protocols 1

Special Considerations and Pitfalls

• Avoid splenectomy during active AML treatment due to high surgical risk and immunosuppression concerns 1, 5
• Carefully monitor for infections as both ITP treatments (corticosteroids, rituximab) and AML therapy cause immunosuppression 1, 6
• Be cautious with TPO-RAs in AML patients due to theoretical concerns about stimulating leukemic blast proliferation, although clinical evidence is limited 3, 6
• Recognize drug interactions between ITP treatments and AML chemotherapy agents, particularly with respect to hepatic metabolism 4
• Monitor for thrombotic risk, which can be elevated in both ITP and AML, especially when using TPO-RAs 1, 5

Long-term Management

• Once AML is in remission, reassess ITP status as bone marrow recovery may impact platelet counts 1, 7
• For persistent ITP after AML remission, follow standard ITP management guidelines with consideration of TPO-RAs or rituximab before splenectomy 1
• Regular monitoring of platelet counts is essential during and after AML treatment to distinguish between ITP flares and AML relapse 1, 7