ELN Foundation and France National Cancer Institute.

Mutations in the Bcr-Abl kinase domain (KD) may cause, or contribute to, resistance to tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia (CML) patients.Recommendations aimed to rationalize the use of BCR-ABL mutation testing in CML have been compiled by a panel of experts appointed by the European LeukemiaNet (ELN) and European Treatment and Outcome Study (EUTOS) and are here reported. Based on a critical review of the literature and, whenever necessary, on panelists' experience, key issues were identified and discussed concerning: i) when to perform mutation analysis; ii) how to perform it; iii) how to translate results into clinical practice. In chronic phase patients receiving imatinib first-line, mutation analysis is recommended only in case of failure or suboptimal response according to the ELN criteria. In imatinib-resistant patients receiving an alternative TKI, mutation analysis is recommended in case of hematologic or cytogenetic failure as provisionally defined by the ELN. The recommended methodology is direct sequencing, although it may be preceded by screening with other techniques like denaturing-high performance liquid chromatography. In all the cases outlined above, a positive result is an indication for therapeutic change. Some specific mutations weigh on TKI selection.

Although imatinib, a BCR-ABL tyrosine kinase inhibitor, is used to treat acute Philadelphia chromosome-positive (Ph ؉ ) leukemia, it does not prevent central nervous system (CNS) relapses resulting from poor drug penetration through the blood-brain barrier. Imatinib and dasatinib (a dual-specific SRC/BCR-ABL kinase inhibitor) were compared in a preclinical mouse model of intracranial Ph ؉ leukemia. Clinical dasatinib treatment in patients with CNS Ph ؉ leukemia was assessed. In preclinical studies, dasatinib increased survival, whereas imatinib failed to inhibit intracranial tumor growth. Stabilization and regression of CNS disease were achieved with continued dasatinib administration. The drug also demonstrated substantial activity in 11 adult and pediatric patients with CNS Ph ؉ leukemia. Eleven evaluable patients had clinically significant, long-lasting responses, which were complete in 7 patients. In 3 additional patients, isolated CNS relapse occurred during dasatinib therapy; and in 2 of them, it was caused by expansion of a BCR-ABL-mutated dasatinibresistant clone, implying selection pressure exerted by the compound in the CNS. Dasatinib has promising therapeutic potential in managing intracranial leukemic disease and substantial clinical activity in patients who experience CNS relapse while on imatinib therapy. This study is registered at ClinicalTrials. gov as CA180006 (#NCT00108719) and

Biologic and clinical observations suggest that combining imatinib with IFN-␣ may improve treatment outcome in chronic myeloid leukemia (CML). We randomized newly diagnosed chronic-phase CML patients with a low or intermediate Sokal risk score and in imatinib-induced complete hematologic remission either to receive a combination of pegylated IFN␣2b (Peg-IFN-␣2b) 50 g weekly and imatinib 400 mg daily (n ‫؍‬ 56) or to receive imatinib 400 mg daily monotherapy (n ‫؍‬ 56). The primary endpoint was the major molecular response (MMR) rate at 12 months after randomization. In both arms, 4 patients (7%) discontinued imatinib treatment (1 because of blastic transformation in imatinib arm). In addition, in the combination arm, 34 patients (61%) discontinued Peg-IFN-␣2b, most because of toxicity. The MMR rate at 12 months was significantly higher in the imatinib plus Peg-IFN-␣2b arm (82%) compared with the imatinib monotherapy arm (54%; intention-to-treat, P ‫؍‬ .002). The MMR rate increased with the duration of Peg-IFN␣2b treatment (< 12-week MMR rate 67%, > 12-week MMR rate 91%). Thus, the addition of even relatively short periods of Peg-IFN-␣2b to imatinib markedly increased the MMR rate at 12 months of therapy. Lower doses of Peg-IFN-␣2b may enhance tolerability while retaining efficacy and could be considered in future protocols with curative intent. (Blood. 2011;118(12):3228-3235)

Objective-The high and low responder phenomenon describes individual differences in lipopolysaccharide (LPS)-induced monocyte tissue factor (TF) activity. We characterized patterns of intracellular accumulation, externalization, and shedding of TF in response to LPS in mononuclear cells (MNCs) from high responders (HRs) and low responders (LRs). T ightly controlled exposure of tissue factor (TF) to components of the plasma coagulation cascade is important for maintenance of normal rheological properties of blood. Failure to manipulate TF levels available for the initiation of blood clotting leads to thrombotic or bleeding disorders in humans. Circulating monocytes are presumably the major cell type that respond to variable stimuli by developing coagulant activity 1 through the expression of TF. 2 Originally, intersubject variability in developing of monocyte TF activity was described by Østerud et al. 3 By comparing lipopolysaccharide (LPS)-induced monocyte TF activity and tumor necrosis factor-␣ (TNF-␣) production in a whole blood system, an up to a 50-fold difference between individuals was observed. 4 This finding was defined as the "highlow responder phenomenon." 4 Also noteworthy, the individual usually remains a high responder (HR) or low responder (LR) for several years. 5,6 Later, high intersubject variability in cytokine production by LPS-stimulated monocytes was demonstrated. 7 It was also shown that patients with high levels of TNF-␣ production were more susceptible to heart transplant rejection. 8 Monocytes isolated from septic shock patient survivors revealed higher TNF-␣ production than monocytes from nonsurvivors. 9 Many studies have been undertaken to describe the significance of this phenomenon, but so far, no general explanation has been found. Diverse plasma factors and direct cell interactions play an important role in the development of monocyte TF activity. 10 -15 High expression of monocyte TF activity is associated with higher risk of acute coronary syndrome. 16 Platelets have been suggested to be responsible for inducing monocyte TF activity. 17 Platelet-rich plasma induced significantly higher TF activity in LPS-stimulated monocytes than platelet-poor plasma. 18 Moreover, when blood cells without platelets from HRs were mixed with platelet-rich plasma of an LR, LPS-induced TF activity was reduced up to 76% compared with an autologous system. 18 It was shown that granulocytes enhance LPSinduced monocyte TF activity in a platelet-dependent reaction involving P-selectin, platelet factor 4, plateletactivating factor, hydroxyl-eicosatetraenoic acid, and platelet-derived growth factor. 18 -21 Here we report several observations concerning the relationships between intracellular-and membrane-located TF antigen in resting and LPS-stimulated monocytes in groups of HRs and LRs, using fluorescence-activated cell sorter (FACS) analysis, fluorescence confocal microscopy, in-cell Methods and Results-After Materials and Methods Blood Sampling and Experimental DesignBlood samples from 16 healthy ...