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Infants with KMT2A ‐rearranged acute lymphoblastic leukemia ( KMT2A -r ALL) have a poor prognosis. KMT2A -r ALL overexpresses FLT3, and the FLT3 inhibitor (FLT3i) lestaurtinib potentiates chemotherapy‐induced cytotoxicity in preclinical models. Children’s Oncology Group (COG) AALL0631 tested whether adding lestaurtinib to post‐induction chemotherapy improved event-free survival (EFS). After chemotherapy induction, KMT2A -r infants received either chemotherapy only or chemotherapy plus lestaurtinib. Correlative assays included FLT3i plasma pharmacodynamics (PD), which categorized patients as inhibited or uninhibited, and FLT3i ex vivo sensitivity (EVS), which categorized leukemic blasts as sensitive or resistant. There was no difference in 3-year EFS between patients treated with chemotherapy plus lestaurtinib ( n  = 67, 36 ± 6%) vs. chemotherapy only ( n  = 54, 39 ± 7%, p  = 0.67). However, for the lestaurtinib-treated patients, FLT3i PD and FLT3i EVS significantly correlated with EFS. For FLT3i PD, EFS for inhibited/uninhibited was 59 ± 10%/28 ± 7% ( p  = 0.009) and for FLTi EVS, EFS for sensitive/resistant was 52 ± 8%/5 ± 5% ( p  < 0.001). Seventeen patients were both inhibited and sensitive, with an EFS of 88 ± 8%. Adding lestaurtinib did not improve EFS overall, but patients achieving potent FLT3 inhibition and those whose leukemia blasts were sensitive FLT3-inhibition ex vivo did benefit from the addition of lestaurtinib. Patient selection and PD-guided dose escalation may enhance the efficacy of FLT3 inhibition for KMT2A -r infant ALL.

Chemoimmunotherapy has led to improved numbers of patients achieving disease response, and longer overall survival in young patients with chronic lymphocytic leukaemia; however, its application in elderly patients has been restricted by substantial myelosuppression and infection. We aimed to assess safety and activity of ibrutinib, an orally administered covalent inhibitor of Bruton tyrosine kinase (BTK), in treatment-naive patients aged 65 years and older with chronic lymphocytic leukaemia. In our open-label phase 1b/2 trial, we enrolled previously untreated patients at clinical sites in the USA. Eligible patients were aged at least 65 years, and had symptomatic chronic lymphocytic leukaemia or small lymphocytic lymphoma requiring therapy. Patients received 28 day cycles of once-daily ibrutinib 420 mg or ibrutinib 840 mg. The 840 mg dose was discontinued after enrolment had begun because comparable activity of the doses has been shown. The primary endpoint was the safety of the dose-fixed regimen in terms of frequency and severity of adverse events for all patients who received treatment. This study is registered with ClinicalTrials.gov, number NCT01105247. Between May 20, 2010, and Dec 18, 2012, we enrolled 29 patients with chronic lymphocytic leukaemia and two patients with small lymphocytic lymphoma. Median age was 71 years (range 65–84), and 23 (74%) patients were at least 70 years old. Toxicity was mainly of mild-to-moderate severity (grade 1–2). 21 (68%) patients had diarrhoea (grade 1 in 14 [45%] patients, grade 2 in three [10%] patients, and grade 3 in four [13%] patients). 15 (48%) patients developed nausea (grade 1 in 12 [39%] patients and grade 2 in three [10%] patients). Ten (32%) patients developed fatigue (grade 1 in five [16%] patients, grade 2 in four [13%] patients, and grade 3 in one [3%] patient). Three (10%) patients developed grade 3 infections, although no grade 4 or 5 infections occurred. One patient developed grade 3 neutropenia, and one developed grade 4 thrombocytopenia. After a median follow-up of 22·1 months (IQR 18·4–23·2), 22 (71%) of 31 patients achieved an objective response (95% CI 52·0–85·8); four patients (13%) had a complete response, one patient (3%) had a nodular partial response, and 17 (55%) patients had a partial response. The safety and activity of ibrutinib in elderly, previously untreated patients with symptomatic chronic lymphocytic leukaemia, or small lymphocytic lymphoma is encouraging, and merits further investigation in phase 3 trials. Pharmacyclics, Leukemia and Lymphoma Society, D Warren Brown Foundation, Mr and Mrs Michael Thomas, Harry Mangurian Foundation, P50 CA140158 to Prof J C Byrd MD.

A phase II clinical trial with single-agent decitabine was conducted in older patients (≥60 years) with previously untreated acute myeloid leukemia (AML) who were not candidates for or who refused intensive chemotherapy. Subjects received low-dose decitabine at 20 mg/m² i.v. over 1 h on days 1 to 10. Fifty-three subjects enrolled with a median age of 74 years (range, 60-85). Nineteen (36%) had antecedent hematologic disorder or therapy-related AML; 16 had complex karyotypes (≥3 abnormalities). The complete remission rate was 47% (n = 25), achieved after a median of three cycles of therapy. Nine additional subjects had no morphologic evidence of disease with incomplete count recovery, for an overall response rate of 64% (n = 34). Complete remission was achieved in 52% of subjects presenting with normal karyotype and in 50% of those with complex karyotypes. Median overall and disease-free survival durations were 55 and 46 weeks, respectively. Death within 30 days of initiation of treatment occurred in one subject (2%), death within 8 weeks in 15% of subjects. Given the DNA hypomethylating effect of decitabine, we examined the relationship of clinical response and pretreatment level of miR-29b, previously shown to target DNA methyltransferases. Higher levels of miR-29b were associated with clinical response (P = 0.02). In conclusion, this schedule of decitabine was highly active and well tolerated in this poor-risk cohort of older AML patients. Levels of miR-29b should be validated as a predictive factor for stratification of older AML patients to decitabine treatment.

Charles Mullighan and colleagues report a recurrent rearrangement of CRLF2 in B-progenitor and Down syndrome-associated acute lymphoblastic leukemia. Their genetic and functional evidence indicates that CRLF2 cooperates with activated JAK2 to promote leukemogenesis. Aneuploidy and translocations are hallmarks of B-progenitor acute lymphoblastic leukemia (ALL), but many individuals with this cancer lack recurring chromosomal alterations. Here we report a recurring interstitial deletion of the pseudoautosomal region 1 of chromosomes X and Y in B-progenitor ALL that juxtaposes the first, noncoding exon of P2RY8 with the coding region of CRLF2 . We identified the P2RY8-CRLF2 fusion in 7% of individuals with B-progenitor ALL and 53% of individuals with ALL associated with Down syndrome. CRLF2 alteration was associated with activating JAK mutations, and expression of human P2RY8-CRLF2 together with mutated mouse Jak2 resulted in constitutive Jak-Stat activation and cytokine-independent growth of Ba/F3 cells overexpressing interleukin-7 receptor alpha. Our findings indicate that these two genetic lesions together contribute to leukemogenesis in B-progenitor ALL.

Adolescent and young adult (AYA) patients 16–30 years old with high-risk acute lymphoblastic leukemia (HR-ALL) have inferior outcomes compared to younger HR-ALL patients. AALL0232 was a Phase 3 randomized Children’s Oncology Group trial for newly diagnosed HR B-ALL (1–30 years). Between 2004 and 2011, 3154 patients enrolled with 3040 eligible and evaluable for induction. AYA patients comprised 20% of patients (16–21 years, n = 551; 22–30 years, n = 46). 5-year event-free survival and overall survival was 65.4 ± 2.2% and 77.4 ± 2.0% for AYA patients compared to 78.1 ± 0.9% and 87.3 ± 0.7% for younger patients (p < 0.0001). Five-year cumulative incidence of relapse was 18.5 ± 1.7% for AYA patients and 13.5 ± 0.7% for younger patients (p = 0.006), largely due to increased marrow relapses (14.0 ± 1.5% versus 9.1 ± 0.6%; p < 0.0001). Additionally, induction failure rate was higher in AYA (7.2 ± 1.1% versus 3.5 ± 0.4%; p < 0.001) and post-induction remission deaths were significantly higher in AYA (5.7 ± 1.0% versus 2.4 ± 0.3%; p < 0.0001). AALL0232 enrolled the largest number of AYA B-ALL patients to date, demonstrating significantly inferior survival and greater rates of treatment-related toxicities compared to younger patients. Although treatment intensification has improved outcomes in younger patients, they have not been associated with the same degree of improvement for older patients.

Errors in chromosome segregation during gametogenesis, such as nondisjunction (NDJ) errors, have severe consequences in human reproduction, and a better understanding of their etiology is of fundamental interest in genetics. Mapping NDJ errors to meiotic/mitotic stages typically requires proband-parent comparison, limiting its applicability. Herein, we develop Mis-segregation Error Identification through Hidden Markov Models (MeiHMM), a method for inferring NDJ error stage and crossover events based on only genomic data of trisomic probands. Guided by triallelic genotype/haplotype configurations, MeiHMM discerns the allelic origin at each locus, which informs NDJ error during gamete formation, without identifying the parental origin of the trisomy. In 152 Down syndrome (DS) cases, MeiHMM achieved an accuracy of 96.1% in classifying NDJ errors, with a sensitivity of 91.6% in crossover identification, compared to proband-parents trio analysis. 17% of Meiosis II errors were misclassified as Meiosis I, mainly due to small proximal crossover events. Applying MeiHMM to 509 children with DS-associated childhood leukemia, we demonstrate that NDJ error is associated with the age of disease onset, somatic genomic abnormalities, and prognosis. Thus, MeiHMM is an effective method for trisomic NDJ error classification and crossover identification that can be applied broadly to study the etiology of congenital aneuploidy conditions. The authors report a computational framework for determining the meiotic/mitotic origin of nondisjunction (NDJ) in trisomies without parental data. Applying this to Down syndrome, they uncover links between NDJ error stage and leukemia genomics.

Rare, recurrent balanced translocations occur in a variety of cancers but are often not functionally interrogated. Balanced translocations with the immunoglobulin heavy chain locus ( IGH ; 14q32) in chronic lymphocytic leukemia (CLL) are infrequent but have led to the discovery of pathogenic genes including CCND1 , BCL2 , and BCL3 . Following identification of a t(X;14)(q28;q32) translocation that placed the mature T cell proliferation 1 gene ( MTCP1 ) adjacent to the immunoglobulin locus in a CLL patient, we hypothesized that this gene may have previously unrecognized importance. Indeed, here we report overexpression of human MTCP1 restricted to the B cell compartment in mice produces a clonal CD5 + /CD19 + leukemia recapitulating the major characteristics of human CLL and demonstrates favorable response to therapeutic intervention with ibrutinib. We reinforce the importance of genetic interrogation of rare, recurrent balanced translocations to identify cancer driving genes via the story of MTCP1 as a contributor to CLL pathogenesis. Some genes that are part of balanced translocations are reported as drivers for tumourigenesis. Here, the authors report a translocation involving MTCP1 in chronic lymphocytic leukemia and show that MTCP1 overexpression leads to the disease in a murine model.

Studies of chronic lymphocytic leukemia (CLL) have yielded substantial progress, however a lack of immortalized cell lines representative of the primary disease has hampered a full understanding of disease pathogenesis and development of new treatments. Here we describe a novel CLL cell line (OSU-CLL) generated by EBV transformation, which displays a similar cytogenetic and immunophenotype observed in the patient's CLL (CD5 positive with trisomy 12 and 19). A companion cell line was also generated from the same patient (OSU-NB). This cell line lacked typical CLL characteristics, and is likely derived from the patient's normal B cells. In vitro migration assays demonstrated that OSU-CLL exhibits migratory properties similar to primary CLL cells whereas OSU-NB has significantly reduced ability to migrate spontaneously or towards chemokine. Microarray analysis demonstrated distinct gene expression patterns in the two cell lines, including genes on chromosomes 12 and 19, which is consistent with the cytogenetic profile in this cell line. Finally, OSU-CLL was readily transplantable into NOG mice, producing uniform engraftment by three weeks with leukemic cells detectable in the peripheral blood spleen and bone marrow. These studies describe a new CLL cell line that extends currently available models to study gene function in this disease.

Cancer stem cells (CSCs) have been identified in hematopoietic and solid tumors. However, their precursors-namely, precancerous stem cells (pCSCs) -have not been characterized. Here we experimentally define the pCSCs that have the potential for both benign and malignant differentiation, depending on environmental cues. While clonal pCSCs can develop into various types of tissue cells in immunocompetent mice without developing into cancer, they often develop, however, into leukemic or solid cancers composed of various types of cancer cells in immunodeficient mice. The progress of the pCSCs to cancers is associated with the up-regulation of c-kit and Sca-1, as well as with lineage markers. Mechanistically, the pCSCs are regulated by the PIWI/AGO family gene called piwil2. Our results provide clear evidence that a single clone of pCSCs has the potential for both benign and malignant differentiation, depending on the environmental cues. We anticipate pCSCs to be a novel target for the early detection, prevention, and therapy of cancers.