Nicolas Boissel

Should Adolescents With Acute Lymphoblastic Leukemia Be Treated as Old Children or Young Adults? Comparison of the French FRALLE-93 and LALA-94 Trials

PURPOSE To compare pediatric and adult therapeutic practices in the treatment of acute lymphoblastic leukemia (ALL) in adolescents. PATIENTS AND METHODS From June 1993 to September 1994, 77 and 100 adolescents (15 to 20 years of age) were enrolled in the pediatric FRALLE-93 and adult LALA-94 protocols, respectively. Among the different prognostic factors, we retrospectively analyzed the effect of the trial on achieving complete remission (CR) and event-free survival (EFS). RESULTS Patients were younger in the FRALLE-93 than in the LALA-94 protocol (median age, 15.9 v 17.9 years, respectively), but other characteristics were similar, including median WBC count (18 x 10(9) cells/L v 16 x 10(9) cells/L), B/T-lineage (54 of 23 v 72 of 28 patients), CD10-negative ALL (13% v 15%), and poor-risk cytogenetics (t(9;22), t(4;11), or hypodiploidy less than 45 chromosomes: 6% v 5%). The CR rate depended on WBC count (P =.005) and trial (94% v 83% in FRALLE-93 and LALA-94, respectively; P =.04). Univariate analysis showed that unfavorable prognostic factors for EFS were as follows: the trial (estimated 5-year EFS, 67% v 41% for FRALLE-93 and LALA-94, respectively; P <.0001), an increasing WBC count (P <.0001), poor-risk cytogenetics (P =.005), and T-lineage (P =.01). The trial and WBC count remained significant parameters for EFS in multivariate analysis (P <.0001 and P =.0004). Lineage subgroup analysis showed an advantage for the FRALLE-93 trial for CR achievement (98% v 81%; P =.002) and EFS (P =.0002) in B-lineage ALL and for EFS (P =.05) in T-lineage ALL. Age was not a significant prognostic factor in this population of adolescents. CONCLUSION This studys findings indicate that adolescents should be included in intensive pediatric protocols and that new trials should be designed, inspired by pediatric protocols, for the treatment of young adults with ALL.

Cooperating gene mutations in acute myeloid leukemia: a review of the literature

Acute myeloid leukemia (AML) is a heterogeneous group of neoplastic disorders with great variability in clinical course and response to therapy, as well as in the genetic and molecular basis of the pathology. Major advances in the understanding of leukemogenesis have been made by the characterization and the study of acquired cytogenetic abnormalities, particularly reciprocal translocations observed in AML. Besides these major cytogenetic abnormalities, gene mutations also constitute key events in AML pathogenesis. In this review, we describe the contribution of known gene mutations to the understanding of AML pathogenesis and their clinical significance. To gain more insight in this understanding, we clustered these alterations in three groups: (1) mutations affecting genes that contribute to cell proliferation (FLT3, c-KIT, RAS, protein tyrosine standard phosphatase nonreceptor 11); (2) mutations affecting genes involved in myeloid differentiation (AML1 and CEBPA) and (3) mutations affecting genes implicated in cell cycle regulation or apoptosis (P53, NPM1). This nonexhaustive review aims to show how gene mutations interact with each other, how they contribute to refine prognosis and how they can be useful for risk-adapted therapeutic management of AML patients.

Incidence and prognostic impact of c-Kit , FLT3 , and Ras gene mutations in core binding factor acute myeloid leukemia (CBF-AML)

In core binding factors (CBF) acute myeloid leukemia (AML), the disruption of CBFα/β genes impairs normal hematopoietic differentiation and is supposed to cooperate with additional mutations promoting proliferation. The incidence and the prognosis of receptor tyrosine kinase (RTK) c-Kit and FLT3 mutations and Ras mutations were evaluated in 103 pediatric and adult patients with CBF-AML. c-Kit mutations were present in 17% patients. c-Kit exon 8 mutations were more frequent in inv(16) than in t(8;21) subset (20 versus 6%). Only one patient had FLT3-ITD but FLT3-D835 was as frequent as reported in AML population (7%). Ras mutations were significantly more frequent in inv(16) than in t(8;21) subset (36 versus 8%, P=0.001). RTK mutations were associated with a higher white blood cell count (WBC) (36 versus 21 G/L, P=0.05). FLT3 mutations were significantly associated with a shorter EFS and survival (P<0.0001 and P=0.0002) owing to an excess of early events. c-Kit mutations were associated with a shorter EFS and RFS (P=0.002 and P=0.003) in t(8;21) but not inv(16) patients. As previously observed, Ras mutations did not affect prognosis. Screening for RTK mutations may help to identify patients with a more adverse outcome and thus susceptible to benefit from intensified protocols or RTK inhibitors.

Prognostic Impact of Isocitrate Dehydrogenase Enzyme Isoforms 1 and 2 Mutations in Acute Myeloid Leukemia: A Study by the Acute Leukemia French Association Group

PURPOSE Recently, whole-genome sequencing in acute myeloid leukemia (AML) identified recurrent isocitrate dehydrogenase enzyme isoform (IDH1) mutations (IDH1m), previously reported to be involved in gliomas as well as IDH2 mutations (IDH2m). The prognosis of both IDH1m and IDH2m in AML remains unclear. PATIENTS AND METHODS The prevalence and the prognostic impact of R132 IDH1 and R172 IDH2 mutations were evaluated in a cohort of 520 adults with AML homogeneously treated in the French Acute Leukemia French Association (ALFA) -9801 and -9802 trials. RESULTS The prevalence of IDH1m and IDH2m was 9.6% and 3.0%, respectively, mostly associated with normal cytogenetics (CN). In patients with CN-AML, IDH1m were associated with NPM1m (P = .008), but exclusive of CEBPAm (P = .03). In contrary, no other mutations were detected in IDH2m patients. In CN-AML patients, IDH1m were found in 19% of favorable genotype ([NPM1m or CEBPAm] without fms-related tyrosine kinase 3 [FLT3] internal tandem duplication [ITD]) and were associated with a higher risk of relapse (RR) and a shorter overall survival (OS). Favorable genotype in CN-AML could thus be defined by the association of NPM1m or CEBPAm with neither FLT3-ITD nor IDH1m. In IDH2m CN-AML patients, we observed a higher risk of induction failure, a higher RR and a shorter OS. In multivariate analysis, age, WBC count, the four-gene favorable genotype and IDH2m were independently associated with a higher RR and a shorter OS. CONCLUSION Contrarily to what is reported in gliomas, IDH1m and IDH2m in AML are associated with a poor prognosis. Screening of IDH1m could help to identify high-risk patients within the subset of CN-AML with a favorable genotype.

A phase 1 trial of the anti-inhibitory KIR mAb IPH2101 for AML in complete remission

IPH2101 is an anti-killer inhibitory receptor (anti-KIR) mAb that can block KIR-mediated inhibition of natural killer (NK) cells to enhance cytotoxicity against acute myeloid leukemia blasts. We have conducted a phase 1 study of IPH2101 in elderly patients with acute myeloid leukemia in first complete remission. Patients received escalating doses (0.0003-3 mg/kg) of IPH2101 following a 3 + 3 design. Safety, toxicity (primary end points), pharmacokinetics, outcome, and immunologic correlates were evaluated. Twenty-three patients (median age, 71 years), were enrolled. Adverse events were mild and transient, consisting mainly of infusion syndrome and erythema. The maximum tolerated dose was not reached, although full KIR saturation (> 90%) was sustained for more than 2 weeks at 1 and 3 mg/kg. There was a clear correlation between mAb exposure and KIR occupancy. Neither hematologic toxicity nor significant changes in the numbers and distribution of lymphocyte subsets, NK cell receptor expression, or in vitro cytotoxicity were seen. At the highest dose levels (0.3, 1, and 3 mg/kg), transient increases in TNF-α and MIP-1β serum concentrations and NK cell CD69 expression were observed. Overall and relapse-free survival in the present study compared favorably to reports in comparable patient populations. We conclude that IPH2101 administration is safe and can block KIR for prolonged periods of time with limited side effects. Registered with the European Union Drug Regulating Authorities Clinical Trials (EUDRACT) as 2005-005298-31.

Prospective evaluation of gene mutations and minimal residual disease in patients with core binding factor acute myeloid leukemia

Not all patients with core binding factor acute myeloid leukemia (CBF-AML) display a good outcome. Modern risk factors include KIT and/or FLT3 gene mutations and minimal residual disease (MRD) levels, but their respective values have never been prospectively assessed. A total of 198 CBF-AML patients were randomized between a reinforced and a standard induction course, followed by 3 high-dose cytarabine consolidation courses. MRD levels were monitored prospectively. Gene mutations were screened at diagnosis. Despite a more rapid MRD decrease after reinforced induction, induction arm did not influence relapse-free survival (RFS) (64% in both arms; P = .91). Higher WBC, KIT, and/or FLT3-ITD/TKD gene mutations, and a less than 3-log MRD reduction after first consolidation, were associated with a higher specific hazard of relapse, but MRD remained the sole prognostic factor in multivariate analysis. At 36 months, cumulative incidence of relapse and RFS were 22% vs 54% (P < .001) and 73% vs 44% (P < .001) in patients who achieved 3-log MRD reduction vs the others. These results suggest that MRD, rather than gene mutations, should be used for future treatment stratifications in CBF-AML patients. This trial was registered at EudraCT as #2006-005163-26 and at www.clinicaltrials.gov as #NCT 00428558.

NOTCH is a key regulator of human T-cell acute leukemia initiating cell activity.

Understanding the pathways that regulate the human T-cell acute lymphoblastic leukemia (T-ALL) initiating cells (T-LiC) activity has been hampered by the lack of biologic assays in which this human disease can be studied. Here we show that coculture of primary human T-ALL with a mouse stromal cell line expressing the NOTCH ligand delta-like-1 (DL1) reproducibly allowed maintenance of T-LiC and long-term growth of blast cells. Human T-ALL mutated or not on the NOTCH receptor required sustained activation of the NOTCH pathway via receptor/ligand interaction for growth and T-LiC activity. On the reverse, inhibition of the NOTCH pathway during primary cultures abolished in vitro cell growth and in vivo T-LiC activity. Altogether, these results demonstrate the major role of the NOTCH pathway activation in human T-ALL development and in the maintenance of leukemia-initiating cells.

Targeting iron homeostasis induces cellular differentiation and synergizes with differentiating agents in acute myeloid leukemia

Differentiating agents have been proposed to overcome the impaired cellular differentiation in acute myeloid leukemia (AML). However, only the combinations of all-trans retinoic acid or arsenic trioxide with chemotherapy have been successful, and only in treating acute promyelocytic leukemia (also called AML3). We show that iron homeostasis is an effective target in the treatment of AML. Iron chelating therapy induces the differentiation of leukemia blasts and normal bone marrow precursors into monocytes/macrophages in a manner involving modulation of reactive oxygen species expression and the activation of mitogen-activated protein kinases (MAPKs). 30% of the genes most strongly induced by iron deprivation are also targeted by vitamin D3 (VD), a well known differentiating agent. Iron chelating agents induce expression and phosphorylation of the VD receptor (VDR), and iron deprivation and VD act synergistically. VD magnifies activation of MAPK JNK and the induction of VDR target genes. When used to treat one AML patient refractory to chemotherapy, the combination of iron-chelating agents and VD resulted in reversal of pancytopenia and in blast differentiation. We propose that iron availability modulates myeloid cell commitment and that targeting this cellular differentiation pathway together with conventional differentiating agents provides new therapeutic modalities for AML.

BCR/ABL Oncogene Directly Controls MHC Class I Chain-Related Molecule A Expression in Chronic Myelogenous Leukemia

MHC class I chain-related molecules (MIC) participate in immune surveillance of cancer through engagement of the NKG2D-activating receptor on NK and T cells. Decreased NKG2D expression and function upon chronic exposure to NKG2D ligands and/or soluble forms of MIC (sMIC) may participate in immune escape. In chronic myeloid leukemia, a malignancy caused by the BCR/ABL fusion oncoprotein, we showed cell surface expression of MICA on leukemic, but not healthy, donor hemopoietic CD34+ cells. At diagnosis, chronic myeloid leukemia patients had abnormally high serum levels of sMICA and weak NKG2D expression on NK and CD8+ T cells, which were restored by imatinib mesylate (IM) therapy. In the BCR/ABL+ cell line K562, IM decreased both surface MICA/B expression and NKG2D-mediated lysis by NK cells. Silencing BCR/ABL gene expression directly evidenced its role in the control of MICA expression. IM did not affect MICA mRNA levels, but decreased MICA protein production and release. Sucrose density gradient fractionation of K562 cytoplasmic extracts treated with IM showed a shift in the distribution of MICA mRNA from the polysomal toward the monosomal fractions, consistent with decreased translation. Among the major pathways activated by BCR/ABL that regulate translation, PI3K and mammalian target of rapamycin were shown to control MICA expression. These data provide evidence for direct control of MICA expression by an oncogene in human malignancy and indicate that posttranscriptional mechanisms may participate in the regulation of MICA expression.

Tisagenlecleucel in Children and Young Adults with B-Cell Lymphoblastic Leukemia

Background In a single‐center phase 1–2a study, the anti‐CD19 chimeric antigen receptor (CAR) T‐cell therapy tisagenlecleucel produced high rates of complete remission and was associated with serious but mainly reversible toxic effects in children and young adults with relapsed or refractory B‐cell acute lymphoblastic leukemia (ALL). Methods We conducted a phase 2, single‐cohort, 25‐center, global study of tisagenlecleucel in pediatric and young adult patients with CD19+ relapsed or refractory B‐cell ALL. The primary end point was the overall remission rate (the rate of complete remission or complete remission with incomplete hematologic recovery) within 3 months. Results For this planned analysis, 75 patients received an infusion of tisagenlecleucel and could be evaluated for efficacy. The overall remission rate within 3 months was 81%, with all patients who had a response to treatment found to be negative for minimal residual disease, as assessed by means of flow cytometry. The rates of event‐free survival and overall survival were 73% (95% confidence interval [CI], 60 to 82) and 90% (95% CI, 81 to 95), respectively, at 6 months and 50% (95% CI, 35 to 64) and 76% (95% CI, 63 to 86) at 12 months. The median duration of remission was not reached. Persistence of tisagenlecleucel in the blood was observed for as long as 20 months. Grade 3 or 4 adverse events that were suspected to be related to tisagenlecleucel occurred in 73% of patients. The cytokine release syndrome occurred in 77% of patients, 48% of whom received tocilizumab. Neurologic events occurred in 40% of patients and were managed with supportive care, and no cerebral edema was reported. Conclusions In this global study of CAR T‐cell therapy, a single infusion of tisagenlecleucel provided durable remission with long‐term persistence in pediatric and young adult patients with relapsed or refractory B‐cell ALL, with transient high‐grade toxic effects. (Funded by Novartis Pharmaceuticals; ClinicalTrials.gov number, NCT02435849.)