azd-6244 and Precursor-Cell-Lymphoblastic-Leukemia-Lymphoma

Event-free survival rates at 15 years for paediatric patients with relapsed/refractory acute lymphoblastic leukaemia (ALL) are 30%-50%, with 5-year survival for adult patients only 20%. Many patients with newly diagnosed and relapsed ALL harbour somatic RAS-signalling activation mutations. Induction therapy for ALL involves steroids, with preclinical data suggesting the combination of dexamethasone with the MEK1/2 inhibitor, selumetinib (ARRY-142886) has a synergistic anticancer effect.. Medical ethical committees of all the participating countries have approved the study protocol; initial (UK) ethics approval (17/YH/0123) was granted by Yorkshire & The Humber-Leeds West Research Ethics Committee. Participants are required to provide written informed consent/assent. Results will be disseminated through national and international presentations and peer-reviewed publications.. ISRCTN92323261.

Topics: Adolescent; Adult; Antineoplastic Combined Chemotherapy Protocols; Bayes Theorem; Benzimidazoles; Child; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Dexamethasone; Humans; Precursor Cell Lymphoblastic Leukemia-Lymphoma

Topics: Adolescent; Animals; Bcl-2-Like Protein 11; Benzimidazoles; Child; Child, Preschool; Dexamethasone; DNA Mutational Analysis; Drug Synergism; Female; Glucocorticoids; Humans; Male; Mice; Mice, Inbred NOD; Mice, SCID; Mutation; Neoplasm Transplantation; Precursor Cell Lymphoblastic Leukemia-Lymphoma; ras Proteins; Up-Regulation

Intrachromosomal amplification of chromosome 21 (iAMP21) identifies a high-risk subtype of acute lymphoblastic leukaemia (ALL), requiring intensive treatment to reduce their relapse risk. Improved understanding of the genomic landscape of iAMP21-ALL will ascertain whether these patients may benefit from targeted therapy. We performed whole-exome sequencing of eight iAMP21-ALL samples. The mutation rate was dramatically disparate between cases (average 24.9, range 5-51) and a large number of novel variants were identified, including frequent mutation of the RAS/MEK/ERK pathway. Targeted sequencing of a larger cohort revealed that 60% (25/42) of diagnostic iAMP21-ALL samples harboured 42 distinct RAS pathway mutations. High sequencing coverage demonstrated heterogeneity in the form of multiple RAS pathway mutations within the same sample and diverse variant allele frequencies (VAFs) (2-52%), similar to other subtypes of ALL. Constitutive RAS pathway activation was observed in iAMP21 samples that harboured mutations in the predominant clone (⩾35% VAF). Viable iAMP21 cells from primary xenografts showed reduced viability in response to the MEK1/2 inhibitor, selumetinib, in vitro. As clonal (⩾35% VAF) mutations were detected in 26% (11/42) of iAMP21-ALL, this evidence of response to RAS pathway inhibitors may offer the possibility to introduce targeted therapy to improve therapeutic efficacy in these high-risk patients.

Topics: Animals; Benzimidazoles; Cell Survival; Chromosome Aberrations; Chromosomes, Human, Pair 21; Heterografts; Humans; MAP Kinase Signaling System; Mice; Mutation Rate; Precursor Cell Lymphoblastic Leukemia-Lymphoma; ras Proteins; Sequence Analysis, DNA

Genome-wide studies have identified a high-risk subgroup of pediatric acute lymphoblastic leukemia (ALL) harboring mutations in the Janus kinases (JAK). The purpose of this study was to assess the preclinical efficacy of the JAK1/2 inhibitor AZD1480, both as a single agent and in combination with the MEK inhibitor selumetinib, against JAK-mutated patient-derived xenografts. Patient-derived xenografts were established in immunodeficient mice from bone marrow or peripheral blood biopsy specimens, and their gene expression profiles compared with the original patient biopsies by microarray analysis. JAK/STAT and MAPK signaling pathways, and the inhibitory effects of targeted drugs, were interrogated by immunoblotting of phosphoproteins. The antileukemic effects of AZD1480 and selumetinib, alone and in combination, were tested against JAK-mutated ALL xenografts both in vitro and in vivo. Xenografts accurately represented the primary disease as determined by gene expression profiling. Cellular phosphoprotein analysis demonstrated that JAK-mutated xenografts exhibited heightened activation status of JAK/STAT and MAPK signaling pathways compared with typical B-cell precursor ALL xenografts, which were inhibited by AZD1480 exposure. However, AZD1480 exhibited modest single-agent in vivo efficacy against JAK-mutated xenografts. Combining AZD1480 with selumetinib resulted in profound synergistic in vitro cell killing, although these results were not translated in vivo despite evidence of target inhibition. Despite validation of target inhibition and the demonstration of profound in vitro synergy between AZD1480 and selumetinib, it is likely that prolonged target inhibition is required to achieve in vivo therapeutic enhancement between JAK and MEK inhibitors in the treatment of JAK-mutated ALL.

Topics: Animals; Benzimidazoles; Biopsy; Cell Survival; Child; Gene Expression Regulation, Leukemic; Genetic Association Studies; Humans; Janus Kinases; MAP Kinase Signaling System; Mice; Molecular Targeted Therapy; Mutation; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines; Treatment Outcome; Xenograft Model Antitumor Assays

For most children who relapse with acute lymphoblastic leukemia (ALL), the prognosis is poor, and there is a need for novel therapies to improve outcome. We screened samples from children with B-lineage ALL entered into the ALL-REZ BFM 2002 clinical trial (www.clinicaltrials.gov, #NCT00114348) for somatic mutations activating the Ras pathway (KRAS, NRAS, FLT3, and PTPN11) and showed mutation to be highly prevalent (76 from 206). Clinically, they were associated with high-risk features including early relapse, central nervous system (CNS) involvement, and specifically for NRAS/KRAS mutations, chemoresistance. KRAS mutations were associated with a reduced overall survival. Mutation screening of the matched diagnostic samples found many to be wild type (WT); however, by using more sensitive allelic-specific assays, low-level mutated subpopulations were found in many cases, suggesting that they survived up-front therapy and subsequently emerged at relapse. Preclinical evaluation of the mitogen-activated protein kinase kinase 1/2 inhibitor selumetinib (AZD6244, ARRY-142886) showed significant differential sensitivity in Ras pathway-mutated ALL compared with WT cells both in vitro and in an orthotopic xenograft model engrafted with primary ALL; in the latter, reduced RAS-mutated CNS leukemia. Given these data, clinical evaluation of selumetinib may be warranted for Ras pathway-mutated relapsed ALL.

Topics: Animals; Benzimidazoles; Cell Line, Tumor; Child; Clinical Trials as Topic; Drug Resistance, Neoplasm; Gene Frequency; Genes, ras; Humans; MAP Kinase Kinase Kinases; Mice; Mice, Inbred NOD; Mice, SCID; Mice, Transgenic; Mutation; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Protein Kinase Inhibitors; Recurrence; Signal Transduction; Xenograft Model Antitumor Assays

Topics: Animals; Benzimidazoles; Drug Resistance, Neoplasm; Genes, ras; Humans; Mutation; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Protein Kinase Inhibitors