Time to Abandon the Day 14 Bone Marrow Biopsy in Acute Myeloid Leukemia Patients Receiving Induction Chemotherapy

Background: Bone marrow biopsy on day 14 of induction therapy for patients with acute myeloid leukemia (AML) is a common practice to determine whether re-induction therapy is warranted. A second bone marrow biopsy on day 28 is performed to assess remission status. We desired to explore what proportion of patients received bone marrow biopsies on day 14 at our institution, how many of these biopsies had disease present, and how these results affected clinical decision-making regarding whether re-induction was pursued. We compared outcomes of patients that received re-induction therapy based on bone marrow biopsies on day 14 versus on day 28 or later.

Methods: A single-center retrospective study was performed detailing 252 AML patients that underwent induction therapy between December 1999 and December 2021. Pathology reports were reviewed to document the disease status at day 14 post induction with "7+3” regimen. Response to induction therapy was defined per standard definitions. Statistics are descriptive.

Results: Of the 252 patients, 95 had bone marrow biopsies on day 14. Of these patients, 80 had adequate bone marrow sampling to quantify blast cell percentage. Thirty-four of these patients had no detectable blast cells while 46 had some evidence of disease. Of these 46 patients five (11%) had disease but less than 5% blast cells, 19 (41%) had between 5 and 20% blasts, and 22 (48%) had greater than 20% blasts. Of the 46 patients that still showed some evidence of disease, 7 (15.2%) underwent re-induction. This accounted for 2.78% of the total number of patients. One patient was re-induced with less than 5% blasts, 4 with between 5-20% blasts, and 2 with greater than 20% blasts. The rate of complete remission in patients who received re-induction therapy was 50% for day 14 patients and 46.7% for day 28 or later patients (P<0.43). Of the 15 patients with <20% blasts, 14 had a repeat biopsy and 9 (64.3%) went into remission without re-induction therapy. In the 20 patients with >20% blasts, 18 had a repeat biopsy and 5 (27.8%) went into remission without re-induction.

Conclusions: Even in patients that had evidence of disease on day 14 bone marrow biopsy only a fraction received re-induction therapy. The rates of complete remission were very similar between patients who underwent re-induction based on day 14 bone marrow biopsy results compared to day 28 or later. Increasing availability of lower intensive regimens might lead to more treatment options and further reduce the need for re-induction based on day 14 disease assessment. Future trials need to reevaluate the need for routine evaluation of disease burden on around day 14 post induction therapy.

Kolhe:Cepheid: Honoraria; PGDx: Honoraria, Research Funding; Illumina: Research Funding; Qiagen: Honoraria, Research Funding; Agena: Honoraria, Research Funding; Perkin Elmer: Honoraria, Research Funding; Bioanano INc: Honoraria, Research Funding, Speakers Bureau. Kota:Xcenda: Honoraria; Novartis: Honoraria; Incyte: Honoraria; Ariad: Honoraria; Pfizer Inc: Honoraria, Research Funding.