0195: Identification of patients (pts) with chronic myeloid leukemia (CML) at high risk of artery occlusive events (AOE) during treatment with the 2nd generation tyrosine kinase inhibitor (TKI) nilotinib

BackgroundNilotinib is approved for use in pts with CML after failure of imatinib and in newly diagnosed CP-CML. However, several studies report a nilotinib-associated risk of AOE (arterial occlusive event), especially in pts with preexisting risk factors for CVD. In this study, we aimed at determining whether CVD risk estimation using the 2012 ESC classification could be useful to identify patients at high risk of AOE during nilotinib therapy.MethodsPts (n=75) treated with nilotinib upfront or after failure of prior TKI at our institution were included provided that baseline CVD status could be retrospectively collected. Patients were categorized into 2 groups according to ESC 2012 classification: low/moderate (L/M) and high/very high (H/VH) CVD risk.ResultsAt nilotinib initiation, median age was 51 years (19-76), 41 pts (54.7%) were males. At baseline, medical history revealed H/VH risk category in 15 pts (20%) including established CVD in 6 pts (8%) (all diagnosed before CML), DM (diabete melitus) in 10 pts (13.3%), severe AH (arterial hypertension) in 1 pt (1.3%), familial dyslipidemia in 1 pt (1.3%) and a SCORE ≥5% in 2 pts (2.6%).AOE occurred in 12 pts with myocardial infarction (MI) or coronary heart disease (CHD) (n=3), cerebrovascular events (CeVD) (n=3) and peripheral artery disease (PAD) (n=6). Cumulative incidence of AOE by 48 months was 72.22% (95% CI: 47.46-100) in the H/VH group and only 12.13% (95% CI: 4.32-34.08) in the L/M group. Log Rank comparison of Kaplan Meier analysis of 48-month survival without AOE showed a significant difference between the 2 groups (27.78% (95% CI: 0-58.9) versus 84.38% (95% CI: 67.04-100) p=0.0001). Sensitivity of the ESC classification in nilotinib-treated patients was 67% and specificity 89%.ConclusionsIn our retrospective study, CVD risk estimation according to the 2012 ESC classification reveals that pts who belong to the H/VH risk group at baseline are at very high risk of AOE during nilotinib therapy. In this context, CVD risk should be reassessed throughout therapy and risk factors should be tightly controlled according to current guidelines

In Vivo Activation of cAMP Signaling Induces Growth Arrest and Differentiation in Acute Promyelocytic Leukemia

Differentiation therapy for acute myeloid leukemia uses transcriptional modulators to reprogram cancer cells. The most relevant clinical example is acute promyelocytic leukemia (APL), which responds dramatically to either retinoic acid (RA) or arsenic trioxide (As2O3). In many myeloid leukemia cell lines, cyclic adenosine monophosphate (cAMP) triggers growth arrest, cell death, or differentiation, often in synergy with RA. Nevertheless, the toxicity of cAMP derivatives and lack of suitable models has hampered trials designed to assess the in vivo relevance of theses observations. We show that, in an APL cell line, cAMP analogs blocked cell growth and unraveled As2O3-triggered differentiation. Similarly, in RA-sensitive or RA-resistant mouse models of APL, continuous infusions of 8-chloro-cyclic adenosine monophosphate (8-Cl-cAMP) triggered major growth arrest, greatly enhanced both spontaneous and RA- or As2O3-induced differentiation and accelerated the restoration of normal hematopoiesis. Theophylline, a well-tolerated phosphodiesterase inhibitor which stabilizes endogenous cAMP, also impaired APL growth and enhanced spontaneous or As2O3-triggered cell differentiation in vivo. Accordingly, in an APL patient resistant to combined RA–As2O3 therapy, theophylline induced blast clearance and restored normal hematopoiesis. Taken together, these results demonstrate that in vivo activation of cAMP signaling contributes to APL clearance, independently of its RA-sensitivity, thus raising hopes that other myeloid leukemias may benefit from this therapeutic approach

Mesenchymal stromal cells confer chemoresistance to myeloid leukemia blasts through Side Population functionality and ABC transporter activation

Targeting chemoresistant malignant cells is one of the current major challenges in oncology. Therefore, it is mandatory to refine the characteristics of these cells to monitor their survival and develop adapted therapies. This is of particular interest in acute myeloid leukemia (AML), for which the 5-year survival rate only reaches 30%, regardless of the prognosis. The role of the microenvironment is increasingly reported to be a key regulator for blast survival. In this context, we demonstrate that contact with mesenchymal stromal cells promotes a better survival of blasts in culture in the presence of anthracycline through the activation of ABC transporters. Stroma-dependent ABC transporter activation leads to the induction of a Side Population (SP) phenotype in a subpopulation of primary leukemia blasts through alpha (α)4 engagement. The stroma-promoting effect is reversible and is observed with stromal cells isolated from either healthy donors or leukemia patients. Blasts expressing an SP phenotype are mostly quiescent and are chemoresistant in vitro and in vivo in patient-derived xenograft mouse models. At the transcriptomic level, blasts from the SP are specifically enriched in the drug metabolism program. This detoxification signature engaged in contact with mesenchymal stromal cells represents promising ways to target stroma-induced chemoresistance of AML cells

Outcome of older (≥70 years) APL patients frontline treated with or without arsenic trioxide-an International Collaborative Study

Data on outcome in older (≥70 years) patients with acute promyelocytic leukemia after treatment with arsenic trioxide (ATO) compared with standard chemotherapy (CTX) is scarce. We evaluated 433 patients (median age, 73.4 years) treated either with ATO+ all-trans retinoic acid (ATO/ATRA; n = 26), CTX/ATRA + ATO during consolidation (CTX/ATRA/ATO; n = 148), or with CTX/ATRA (n = 259). Median follow-up for overall survival (OS) was 4.8 years. Complete remissions (CR) were achieved in 92% with ATO/ATRA and 82% with CTX/ATRA; induction death rates were 8% and 18%, respectively. For analysis of postremission outcomes we combined the ATO/ATRA and CTX/ATRA/ATO groups (ATO/ATRA ± CTX). Cumulative incidence of relapse (CIR) was significantly lower after ATO/ATRA ± CTX compared with CTX/ATRA (P 10 × 10 9 /l) white blood cell (WBC) counts at diagnosis were associated with higher CIR (P < 0.001) compared with lower WBC in the CTX/ATRA group, but not in the ATO/ATRA ± CTX group (P = 0.48). ATO, when added to ATRA or CTX/ATRA is feasible and effective in elderly patients for remission induction and consolidation, particularly in patients with high WBC at diagnosis