Blast Clearance Timeline During AML Induction Chemotherapy

Bone Marrow Assessment Timeline

• The National Comprehensive Cancer Network recommends bone marrow aspirate/biopsy should be performed 7-10 days after completion of cytarabine-based chemotherapy to document hypoplasia 1, 2
• For standard-dose cytarabine induction, bone marrow assessment should occur 14-21 days after start of therapy 3

Clinical Monitoring Protocol

• The National Comprehensive Cancer Network recommends CBC with differential should be performed daily during chemotherapy 1, 2
• Differential counts should continue daily during active chemotherapy and every other day after WBC recovery above 500/mcL 1
• Chemistry profile including electrolytes, BUN, creatinine, uric acid, and phosphate should be checked at least daily during active treatment 1, 2

Interpretation of Day 14 Bone Marrow Results

• If hypoplasia is documented, repeat bone marrow at time of hematologic recovery to document remission 1, 2
• If significant residual disease without hypoplasia, consider additional therapy with standard-dose cytarabine and anthracycline or escalation to high-dose cytarabine 3
• If hypoplasia is indeterminate, repeat biopsy in 7-14 days to clarify persistence of leukemia 1, 2

Important Clinical Pitfalls

• When bone marrow contains 5-20% blasts in the setting of recent treatment with no circulating blasts, repeat bone marrow at least one week later is necessary to distinguish relapse from bone marrow regeneration 4
• In acute promyelocytic leukemia (APL) treated with ATRA and chemotherapy, the first post-treatment bone marrow need not be performed until 10-14 days after completion of ATRA therapy 4