[1551] Day 14 Bone Marrow Cellularity Is Superior to CD34 Immunohistochemistry in Predicting Complete Remission in De Novo AML but Not in Secondary/Therapy-Related AML

Gang Zheng, Amy Dezern, Keith W Pratz, Judith E Karp, Christopher Gocke. Johns Hopkins Hospital, Baltimore, MD

Background: The achievement of complete remission (CR) after induction therapy leads to improved survival of AML patients. We previously reported that day 14 bone marrow cellularity is highly predictive of CR in de novo AML but not in secondary/therapy-related AML. In this study we examined the same cohort of patients to evaluate the role of day 14 marrow CD34 immunohistochemistry in predicting CR.
Design: 49 newly diagnosed, previously untreated AML patients received a timed sequential induction regimen of flavopiridol, cytosine arabinoside and mitoxantrone (FLAM) at a single institution. Bone marrow trephine biopsies and aspirates at approximately day 14 of the first cycle of chemotherapy were reviewed and clinical records were abstracted. Immunohistochemical staining for CD34 was performed on routine sections using a standard protocol. Two investigators independently counted 200 cells for CD34 positive blasts.
Results: Mean CD34 count is 21 blasts (range: 1-123)/200 cells for de novo AML, and 25 (range: 2-104) for secondary/therapy-related AML. Interobserver agreement was excellent (Pearson r=0.92, p<0.0001). For de novo AML, low day 14 bone marrow CD34 positive blasts/200 cells is a good predictor for CR (AUC=0.73 by ROC analysis, p=0.04)(Figure 1A), but not as good as cellularity count (AUC=0.98, p<0.0001); for secondary/therapy-related AML, day 14 bone marrow CD34 positive blast count is a poor predictor of CR (AUC=0.56, p=0.69) (Figure 1B), which is similar to cellularity count.

Conclusions: CD34 positive blast count may be helpful in predicting CR when AML is de novo. However, cellularity count is more sensitive and specific as a CR predictor for that cohort. Both cellularity and CD34 positive blast count are not informative in secondary or therapy-related AML. Compared with other measures of remission such as flow cytometry, both cellularity count and CD34 immunohistochemistry are easy and rapid assessments, and they may allow for targeting of de novo AML patients who are unlikely to achieve remission and in need of more aggressive therapy.
Category: Hematopathology

Tuesday, March 5, 2013 8:45 AM

Proffered Papers: Section C, Tuesday Morning


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