MRD at the end of induction and EFS in T-cell lymphoblastic lymphoma: Children's Oncology Group trial AALL1231.

ABSTRACT: Defining prognostic variables in T-lymphoblastic lymphoma (T-LL) remains a challenge. AALL1231 was a Children's Oncology Group phase 3 clinical trial for newly diagnosed patients with T acute lymphoblastic leukemia or T-LL, randomizing children and young adults to a modified augmented Berlin-Frankfurt-Münster backbone to receive standard therapy (arm A) or with addition of bortezomib (arm B). Optional bone marrow samples to assess minimal residual disease (MRD) at the end of induction (EOI) were collected in T-LL analyzed to assess the correlation of MRD at the EOI to event-free survival (EFS). Eighty-six (41%) of the 209 patients with T-LL accrued to this trial submitted samples for MRD assessment. Patients with MRD <0.1% (n = 75) at EOI had a superior 4-year EFS vs those with MRD ≥0.1% (n = 11) (89.0% ± 4.4% vs 63.6% ± 17.2%; P = .025). Overall survival did not significantly differ between the 2 groups. Cox regression for EFS using arm A as a reference demonstrated that MRD EOI ≥0.1% was associated with a greater risk of inferior outcome (hazard ratio, 3.73; 95% confidence interval, 1.12-12.40; P = .032), which was independent of treatment arm assignment. Consideration to incorporate MRD at EOI into future trials will help establish its value in defining risk groups. CT# NCT02112916.

Molecular and phenotypic diversity of CBL-mutated juvenile myelomonocytic leukemia.

Mutations in the gene CBL were first identified in adults with various myeloid malignancies. Some patients with juvenile myelomonocytic leukemia (JMML) were also noted to harbor mutations in CBL, but were found to have generally less aggressive disease courses compared to other forms of Ras pathway-mutant JMML. Importantly, and in contrast to most reports in adults, the majority of CBL mutations in JMML patients are germline with acquired uniparental disomy occurring in affected marrow cells. Here, we systematically studied a large cohort of 33 JMML patients with CBL mutations and found this disease to be highly diverse in presentation and overall outcome. Moreover, we discovered somatically-acquired CBL mutations in 15% of pediatric patients who presented with more aggressive disease. Neither clinical features nor methylation profiling were able to distinguish somatic CBL patients from germline CBL patients, highlighting the need for germline testing. Overall, we demonstrate that disease courses are quite heterogeneous even among germline CBL patients. Prospective clinical trials are warranted to find ideal treatment strategies for this diverse cohort of patients.

Bacteremia in Febrile, Non-neutropenic, and Well-appearing Children With Cancer.

Fever in a neutropenic pediatric oncology patient requires prompt assessment due to the risk of infectious complications. The appropriate management of fever in non-neutropenic patients, however, is not well-established. We describe the rate of bacteremia in a cohort of non-neutropenic pediatric oncology patients with fever at a large institution. Patients were included if they presented to the emergency department or outpatient clinic between 2009 and 2014 with fever, had a central venous catheter (CVC), and were not neutropenic. Three hundred eighty-six episodes of fever occurring in 159 patients were included in the data analysis. Fifty-nine percent of patients were male, 41% had a diagnosis of acute lymphoblastic leukemia, and 90% had a port-a-cath as CVC. The rate of bacteremia was 3.4%; presence of a port-a-cath was protective against bacteremia whereas a white blood cell count >20,000/mm3 was associated with a higher likelihood of bacteremia. Gram-positive microorganisms were most commonly isolated (64.3%) and frequently resistant to cephalosporins. In summary, in our study, the rate of bacteremia was low among non-neutropenic, well-appearing pediatric cancer patients with a CVC and was not associated with any serious medical complications. Prospective research is needed to determine the most appropriate management of these patients.

Experience with ponatinib in paediatric patients with leukaemia.

Ponatinib has proven to be effective in adults with Philadelphia chromosome-positive leukaemias, but data in paediatrics are scarce. Among paediatric patients with chronic myeloid leukaemia (n = 9) or acute lymphoblastic leukaemia (n = 12) treated with varying doses of ponatinib in 13 centres, 71% showed a decrease in disease burden after a median of three months. Ponatinib was well tolerated, with grade 3 toxicities occurring in 29% of patients. Toxicities were similar to those reported in adults, with the exception of arterial thrombotic events, which were not observed. Ponatinib has a favourable safety profile in this paediatric cohort, but dose-finding studies are needed.

Physiological levels of PTEN control the size of the cellular Ins(1,3,4,5,6)P(5) pool.

To understand how a signaling molecule's activities are regulated, we need insight into the processes controlling the dynamic balance between its synthesis and degradation. For the Ins(1,3,4,5,6)P5 signal, this information is woefully inadequate. For example, the only known cytosolic enzyme with the capacity to degrade Ins(1,3,4,5,6)P5 is the tumour-suppressor PTEN [J.J. Caffrey, T. Darden, M.R. Wenk, S.B. Shears, FEBS Lett. 499 (2001) 6 ], but the biological relevance has been questioned by others [E.A. Orchiston, D. Bennett, N.R. Leslie, R.G. Clarke, L. Winward, C.P. Downes, S.T. Safrany, J. Biol. Chem. 279 (2004) 1116 ]. The current study emphasizes the role of physiological levels of PTEN in Ins(1,3,4,5,6)P5 homeostasis. We employed two cell models. First, we used a human U87MG glioblastoma PTEN-null cell line that hosts an ecdysone-inducible PTEN expression system. Second, the human H1299 bronchial cell line, in which PTEN is hypomorphic due to promoter methylation, has been stably transfected with physiologically relevant levels of PTEN. In both models, a novel consequence of PTEN expression was to increase Ins(1,3,4,5,6)P5 pool size by 30-40% (p<0.01); this response was wortmannin-insensitive and, therefore, independent of the PtdIns 3-kinase pathway. In U87MG cells, induction of the G129R catalytically inactive PTEN mutant did not affect Ins(1,3,4,5,6)P(5) levels. PTEN induction did not alter the expression of enzymes participating in Ins(1,3,4,5,6)P5 synthesis. Another effect of PTEN expression in U87MG cells was to decrease InsP6 levels by 13% (p<0.02). The InsP6-phosphatase, MIPP, may be responsible for the latter effect; we show that recombinant human MIPP dephosphorylates InsP6 to D/L-Ins(1,2,4,5,6)P5, levels of which increased 60% (p<0.05) following PTEN expression in U87MG cells. Overall, our data add higher inositol phosphates to the list of important cellular regulators [Y. Huang, R.P. Wernyj, D.D. Norton, P. Precht, M.C. Seminario, R.L. Wange, Oncogene, 24 (2005) 3819 ] the levels of which are modulated by expression of the highly pleiotropic PTEN protein.

Prognostic implications of NOTCH1 and FBXW7 mutations in adults with T-cell acute lymphoblastic leukemia treated on the MRC UKALLXII/ECOG E2993 protocol.

PURPOSE: Notch pathway activation by mutations in either NOTCH1 and/or FBXW7 is one of the most common molecular events in T-cell acute lymphoblastic leukemia (T-ALL) and, in pediatric disease, predicts for favorable outcome. Their prognostic significance in adult T-ALL is unclear. We sought to evaluate the outcome according to mutation status of patients with adult T-ALL treated on the United Kingdom Acute Lymphoblastic Leukaemia XII (UKALLXII)/Eastern Cooperative Oncology Group (ECOG) E2993 protocol. METHODS: NOTCH1 and FBXW7 were screened by a combination of denaturing high-performance liquid chromatography and sequencing in 88 adult patients with T-ALL treated on the UKALLXII/ECOG E2993 protocol and compared with clinical characteristics and outcome. RESULTS: NOTCH1 and FBXW7 mutations were common (60% and 18%, respectively) and were not associated with age or WBC count. NOTCH1 heterodimerization domain mutations were associated with FBXW7 mutations (P = .02), and NOTCH1 proline, glutamic acid, serine, threonine (PEST) rich domain and FBXW7 mutations were mutually exclusive. There were an equal number of high- and standard-risk patients in the NOTCH1 and FBXW7 mutated (MUT) groups. Patients wild type (WT) for both markers trended toward poorer event-free survival (EFS; MUT v WT, 51% v 27%, P = .10; hazard ratio, 0.6). Analysis by each marker individually was not significantly predictive of outcome (NOTCH1 MUT v WT, EFS 49% v 34%, P = .20; FBXW7 MUT v WT, EFS 53% v 41%, P.72). CONCLUSION: NOTCH1 and FBXW7 mutant-positive patients do not fare sufficiently well to warrant an individualized treatment approach in future studies.