Comparison of Peripheral Blast Clearance and Day 14 Bone Marrow Biopsy in Predicting Remission Status and Survival After 7+3 Induction in Acute Myeloid Leukemia.

INTRODUCTION: Induction chemotherapy with cytarabine and an anthracycline (7+3) remains the standard of care for acute myeloid leukemia (AML).

PATIENTS AND METHODS: We retrospectively analyzed 183 newly diagnosed AML patients to compare the utility of rapid peripheral blast clearance (PBC), day of peripheral blast disappearance, residual blasts, and cellularity at day 14 bone marrow biopsy (D14BM) in predicting clinical response to 7+3 induction, overall survival (OS), and relapse-free survival (RFS).

RESULTS: In multivariable logistic regression analysis, day 2 PBC > 85% [P = .0016] was the only predictor of remission status, with sensitivity and specificity of 75%. Peripheral blast disappearance within 5 days after induction and < 10% cellularity in D14BM predicted superior OS and RFS in multivariate analysis. Median follow-up of patients was 28 months since diagnosis. Two-year OS and RFS for patients with ≤ 10% versus > 10% cellularity at D14BM was 60.6% [95% confidence interval (CI), 50.8%-72.2%] versus 32.5% [95% CI, 23.0%-45.8%], and 51.9% [95% CI, 41.9%-64.3%] versus 28.8% [95% CI, 19.1%-43.4%], respectively [P = .0003 for OS and .002 for RFS].

CONCLUSION: Rapid PBC after 7+3 induction showed a significant improvement in specificity compared with D14BM, with similar sensitivity. Neither of these methods were reliably specific tools for the decision of early reinduction, despite their prognostic value. Our findings indicate that morphological cellularity in D14BM is an independent prognostic factor for OS and RFS, regardless of blast percentage, and that ≤ 10% cellularity defines D14BM hypoplasia.