Marrow Hematogones as a Percent of B-Lymphocytes Correlates with Event-Free Survival (EFS) after Allogeneic Bone Marrow Transplant
Payal Sojitra, Zhihong Hu, Yanxia Li, Mala Parthasarathy, Ameet R Kini, Patrick J Stiff, Girish Venkataraman. Loyola University Medical Center, Maywood, IL
Background: Hematogones (HG) are immature B-lymphoid precursors which are increased in a variety of settings after marrow injury. Recent studies indicate that their presence in AML marrows at first complete remission correlates with a decreased risk of relapse. We examined their relevance to outcome in day 100 marrows (d100) of patients in CR who underwent allogeneic bone marrow transplant (aBMT).
Design: From our database of aBMT patients (cord blood n=2; sibling n=15; matched-unrelated, n=7) transplanted (for AML, n=13; ALL, n=2; MDS, n=4; NHL, n=4; MPD, n=1) between 2008-2010, we identified 24 patients with d100 marrow exam and concurrent flow cytometry data available. Clinicopathologic data including age/sex, CD34 stem cell dose, d100 donor chimerism and marrow histology were reviewed. Using 5-color flow cytometric analysis, hematogones (as % of total CD19+B-cells [%HGB] or as % all live event [%HGlive]) were identified besides, % of T-, B-, NK-cells and CD4:CD8 ratios. The primary outcome modeled was EFS (relapse/death).
Results: The mean age of the cohort was 49 years (13 females, 11 males); median follow up was 23 months (range 2-46 mo) after transplant. During this period, there were 8 relapses with 6 deaths (all disease-related). All 8 showed normocellular or hypocellular d100 marrows with >98% d100 donor chimerism in 5/8 with available chimerism data. The mean %HGB of the entire cohort (n=24) was 40.2 (range 0-94.2%). The 8 relapsing patients had significantly lower median %HGB(p=0.008) with virtually absent HGs in 6/8. In univariate Cox regression, only %HGB was a significant predictor of EFS (hazard ratio= 0.96; 95% CI= 0.93, 0.99; p= 0.012) while %HGlive had marginal significance (p=0.06). Age, CD34 stem cell dose, CD4:CD8 ratio, %NK-cells, and %B-cells, did not impact EFS.
Conclusions: Our findings indicate that hematogones may serve as a useful prognostic indicator of subsequent relapse, which could be potentially controlled by early infusions of donor lymphocytes. Further prospective studies using this indicator in a larger cohort of specific disease subsets would clarify its relevance and applicability.
Monday, March 19, 2012 2:45 PM
Platform Session: Section C, Monday Afternoon