Summary
Acute lymphoblastic leukaemia is the most common childhood cancer and for those children who relapse, prognosis is poor and new therapeutic strategies are needed. Recurrent pathways ...implicated in relapse include RAS, JAK STAT, cell cycle, epigenetic regulation, B cell development, glucocorticoid response, nucleotide metabolism and DNA repair. Targeting these pathways is a rational therapeutic strategy and may deliver novel, targeted therapies into the clinic. Relapse often stems from a minor clone present at diagnosis and thus analysis of persisting leukaemia during upfront therapy may allow targeted drug intervention to prevent relapse.
Outcomes of children with high-risk (HR) relapsed acute lymphoblastic leukaemia (ALL) (N = 393), recruited to ALLR3 and ALL-REZ BFM 2002 trials, were analysed. Minimal residual disease (MRD) was ...assessed after induction and at predetermined time points until haematopoietic stem cell transplantation (SCT).
Genetic analyses included karyotype, copy-number alterations and mutation analyses. Ten-year survivals were analysed using Kaplan-Meier and Cox models for multivariable analyses.
Outcomes of patients were comparable in ALLR3 and ALL-REZ BFM 2002. The event-free survival of B-cell precursor (BCP) and T-cell ALL (T-ALL) was 22.6% and 26.2% (P = 0.94), respectively, and the overall survival (OS) was 32.6% and 28.2% (P = 0.11), respectively. Induction failures (38%) were associated with deletions of NR3C1 (P = 0.002) and BTG1 (P = 0.03) in BCP-ALL. The disease-free survival (DFS) and OS in patients with good vs poor MRD responses were 57.4% vs 22.6% (P < 0.0001) and 57.8% vs 32.0% (P = 0.0004), respectively. For BCP- and T-ALL, the post-SCT DFS and OS were 42.1% and 56.8% (P = 0.26) and 51.6% and 55.4% (P = 0.67), respectively. The cumulative incidences of post-SCT relapse for BCP- and T-ALL were 36.9% and 17.8% (P = 0.012) and of death were 10.7% and 25.5% (P = 0.013), respectively. Determinants of outcomes after SCT were acute graft versus host disease, pre-SCT MRD (≥10−3), HR cytogenetics and TP53 alterations in BCP-ALL.
Improvements in outcomes for HR ALL relapses require novel compounds in induction therapy to improve remission rates and immune targeted therapy after induction to maintain remission after SCT.
ALLR3: NCT00967057; ALL REZ-BFM 2002: NCT00114348
•Paediatric high-risk relapsed B- and T-cell leukaemias have comparably poor outcomes.•Determinants of induction failure in high-risk B-cell relapses were identified.•Molecular good responders had better outcomes after stem cell transplantation.•Benchmarks for evaluation of novel immune or targeted therapies were provided.
Summary
Dexamethasone is a key component in the treatment of childhood acute lymphoblastic leukaemia (ALL). Despite playing a key role in the improved survival of ALL over several decades, ...intensification of dexamethasone therapy has also contributed to the increased toxicity associated with treatment, which is now seen to be at unacceptable levels given the favourable disease prognosis. Therefore the focus for treatment is now shifting towards reducing toxicity whilst maintaining current survival rates. As approximately 50% of patients were successfully treated on less intensive protocols of the 1980s, it has been questioned whether therapy intensification is necessary in all patients. Furthermore, there remains a subset of children who are still not cured of their disease. New strategies are therefore needed to identify patients who could benefit from dose reduction or intensification. However, adjusting a potentially life threatening therapy is a challenging task, particularly given the heterogeneous nature of ALL. This review focuses on the potential for patient stratification based on our current knowledge of dexamethasone pharmacokinetics, pharmacogenetics and the action of dexamethasone at the cellular level. A carefully designed, combined approach is needed if we are to achieve the aim of improved personalization of dexamethasone therapy for future patients.
The use of dexamethasone in acute lymphoblastic leukaemia therapy contributes to short- and long-term toxicities. The UKALL 2011 randomised trial investigated whether a more intense dexamethasone ...dose (10 mg/m2/d x 14d, short vs 6 mg/m2/d x 28d, standard) would lead to a more rapid cytoreduction and reduced adverse effects associated with longer durations of steroids in induction. The impact of dose and duration on dexamethasone pharmacokinetics was investigated.
Blood samples were obtained on one of the first three and last three days of induction dexamethasone dosing at time points up to 8 h after oral administration. Plasma dexamethasone levels were quantified in 1084 plasma samples obtained from 174 children and a population pharmacokinetic model developed.
Drug exposure varied significantly between patients, with a >12-fold variation in AUC0–12h values and a marked overlap in dexamethasone exposures between dose levels. Intuitively, AUC0–12h was significantly higher with short dosing (10 mg/m2/d), but cumulative exposure was significantly higher with standard dosing over 28 days, after a higher cumulative dose. Concomitant rasburicase administration was associated with a 60% higher dexamethasone clearance. Day 8 bone marrow response was comparable between dosing arms, but those with <5% blast count exhibited a greater mean dexamethasone exposure than those with >5%. No statistical differences were observed between arms in terms of steroid-related toxicity or minimal residual disease at the end of induction.
The potential significance of dexamethasone AUC0–12h on early response and higher cumulative exposure on the standard arm suggest that duration of therapy and exposure may be more important factors than absolute dose from a clinical pharmacology perspective.
•The impact of dose and duration on dexamethasone pharmacokinetics has been investigated in ALL patients.•Dexamethasone levels were quantified in 1084 plasma samples obtained from 174 children.•Marked interpatient pharmacokinetic variability was observed between patients on different dose levels.•Patients with a day 8 blast count <5% had significantly higher dexamethasone exposures than those with a blast count >5%.•Duration of dexamethasone therapy may be more important than absolute dose from a clinical pharmacology perspective.
Persons with acute HIV infection (AHI) are highly infectious and responsible for a disproportionate share of incident infections. Immediate antiretroviral therapy (ART) rapidly reduces blood viral ...loads (VLs), but genital VLs after ART initiation during AHI are less well described.
Lilongwe, Malawi, 2012-2014.
HIV-seronegative and HIV-serodiscordant persons aged ≥18 years were screened for AHI (RNA positive) and randomized to standard of care, behavioral intervention, or behavioral intervention plus short-term ART (raltegravir/emtricitabine/tenofovir) (1:2:2). Persons who were ART eligible under Malawi guidelines could receive first-line therapy. Blood and genital VLs were assessed at weeks 1, 4, 8, and 12. Fisher's Exact test was used to compare viral suppression by ART status.
Overall, 46 persons with AHI were enrolled; of whom, 17 started ART within 12 weeks. Median blood VL at AHI diagnosis was 836,115 copies/mL. At week 12, 7% (1/14) of those who initiated ART had a blood VL of ≥400 copies/mL, compared with 100% (23/23; P < 0.0001) of those who did not initiate ART (median VL: 61,605 copies/mL). Median genital VL at week 1 was 772 copies/mL, with 13 of 22 (59%) having VL of ≥400 copies/mL. At week 12, 0 of 10 (0%) of those who initiated ART had genital VL of ≥400 copies/mL, compared with 7 of 15 (47%) of those who did not initiate ART (P = 0.02).
Although highly correlated, VLs in blood and genital fluids occupy discrete biological compartments with distinct virologic dynamics. Our results corroborate the dramatic reduction in both compartments after ART initiation. Increasing AHI screening and rapidly initiating treatment is key to interrupting transmission.
Summary
Glucocorticoid (GC) resistance is a continuing clinical problem in childhood acute lymphoblastic leukaemia (ALL) but the underlying mechanisms remain unclear. A proteomic approach was used to ...compare profiles of the B‐lineage ALL GC‐sensitive cell line, PreB 697, and its GC‐resistant sub‐line, R3F9, pre‐ and post‐dexamethasone exposure. PAX5, a transcription factor critical to B‐cell development was differentially regulated in the PreB 697 compared to the R3F9 cell line in response to GC. PAX5 basal protein expression was less in R3F9 compared to its GC‐sensitive parent and confirmed to be lower in other GC‐resistant sub‐lines of Pre B 697 and was associated with a decreased expression of the PAX5 transcriptional target, CD19. Gene set enrichment analysis showed that increasing GC‐resistance was associated with differentiation from preB‐II to an immature B‐lymphocyte stage. GC‐resistant sub‐lines were shown to have higher levels of phosphorylated JNK compared to the parent line and JNK inhibition caused re‐sensitization to GC. Exploiting this maturation may be key to overcoming GC resistance and targeting signalling pathways linked to the maturation state, such as JNK, may be a novel approach.
Loss of heterozygosity (LOH) is detectable in many forms of malignancy, including leukemia, using techniques such as microsatellite analysis and comparative genomic hybridization. However, these ...techniques are laborious and require the use of relatively large amounts of DNA if the whole genome is to be examined. Here we describe the use of oligonucleotide microarrays to characterize single nucleotide polymorphisms (SNPs) in lymphoblasts isolated from children with acute lymphoblastic leukemia for the pan-genomic mapping of LOH with a resolution of 100 to 200 kb. Results were compared with DNA obtained during remission and on relapse. Abnormalities were seen in 8 of 10 cases. The two cases with no abnormalities and one case that showed identical changes at relapse and presentation remain in remission 1 to 9 years following retreatment. The remaining seven patients died following relapse. In four cases, LOH was only detectable at relapse suggesting that progressive LOH may be a cause of disease progression and/or drug resistance. This was supported by detailed analysis of one case in which LOH involving the glucocorticoid receptor was associated with mutation of the remaining allele. The most frequent abnormality detected involved chromosome 9p. In each of the four cases where this was observed LOH included the INK4 locus. In three of the four cases, INK4 loss was only observed at relapse, suggesting that this abnormality may be commonly associated with treatment failure. These observations show that SNP array analysis is a powerful new tool for the analysis of allelic imbalance in leukemic blasts.
Glucocorticoids are pivotal in the treatment of children with acute lymphoblastic leukemia (ALL) and have significant antileukemic effects in the majority of children. However, clinical resistance is ...a significant problem. Although cell line models implicate somatic mutations and loss of heterozygosity (LOH) of the glucocorticoid receptor (GR) gene as a mechanism of in vitro glucocorticoid resistance, the relevance of this mechanism as a cause of clinical resistance in children with ALL is not known. Mutational screening of all coding exons of the GR gene and LOH analyses were done in a large cohort of relapsed ALL. We show that somatic mutations and LOH of the GR rarely contribute to relapsed disease in children with ALL. However, we report the second case of ALL with a somatic mutation of the GR involving a 29-bp deletion in exon 8 and resulting in a truncated protein with loss of part of the ligand-binding domain. There was no evidence of a remaining wild-type allele. Allele-specific PCR detected the mutated clone at day 28 after presentation, which persisted at a low level throughout the disease course before relapse several years later. We hypothesize that the mutated allele present in a leukemic subclone at initial diagnosis was selected for during remission induction with glucocorticoids and contributed to the emergence of a glucocorticoid-resistant cell population.
Abstract Background Fibroblast growth factor receptor 3 (FGFR3) is up-regulated as a result of the t(4;14)(p16;q32) translocation that occurs in up to 20% of multiple myeloma (MM) patients. Recent ...studies have demonstrated that up-regulation of FGFR3 promotes cell survival, growth and drug resistance in malignant plasma cells, both in vitro and in vivo. Therefore, inhibition of FGFR3 signalling is potential target for the chemotherapeutic intervention in t(4;14) MM. Methods Small molecule receptor tyrosine kinase inhibitors (PD173074, sunitinib (SU-11248), vandetanib (ZD6474) and vatalanib (PTK-787)) with varying degrees of inhibitory activity and selectivity against FGFR, were assessed in Ba/f3 cells expressing ZNF198-FGFR1 and MM cell lines. Cell viability, FGFR3 and ZNF198-FGFR1 phosphorylation and apoptosis were evaluated by growth inhibition assays, immunoblotting and fluorescence-activated cell sorting analysis, respectively. An in vivo study was performed with sunitinib in t(4;14)-positive and t(4;14)-negative human MM tumour xenograft models. Results PD173074 and sunitinib differentially inhibited the growth of Ba/f3 cells expressing ZNF198-FGFR1 (GI50 = 10 nM and 730 nM, versus GI50 >1 μM and 2.7 μM for parental cells; p < 0.0001) and t(4;14) positive MM cell lines (GI50 = 4–10 μM and 1–3 μM, versus GI50 = 14–15 μM and 4–5 μM for t(4;14) negative MM cells; p ≤ 0.002). In addition, both PD173074 and sunitinib inhibited the activation of FGFR3 in t(4;14)-positive MM cells. PD173074 and sunitinib induced an apoptotic response in a concentration and time-dependent manner in a t(4;14)-positive (PD174073 and sunitinib) but not a t(4;14)-negative MM cell line (sunitinib only); however, in in vivo tumours derived from the same cell lines, sunitinib was only active in the t(4;14)-negative model. Conclusions These data demonstrate that PD173074 and sunitinib are inhibitors of FGFR3 in MM cell lines, and that sunitinib has in vivo activity in a human MM tumour xenograft model. However, caution should be exercised in using the t(4;14) translocation as a predictive biomarker for patient selection in clinical trials with sunitinib.
Abstract The mismatch repair (MMR) pathway is a post-replicative DNA repair process and MMR deficiency is a common feature of ALL cell lines. In this study we have investigated MMR deficiency in a ...large cohort of primary relapsed ALL ( n = 40) and investigated coding microsatellites (MS) of the lymphoid transcription factors, PAX5 and IKZF1 as downstream target genes. Only one patient showed MMR deficiency, as evidenced by microsatellite instability, which was acquired at relapse and was associated with reduced expression of both MLH1 and MSH2. Coding MS in candidate target genes including PAX5 , IK ZF1, BAX and TGFBRII were all wild type in this patient but the MMR-deficient cell line REH, was confirmed to have a coding MS in both PAX5 and TGFBRII . Whilst MMR deficiency is not highly prevalent in primary ALL, optimisation of the drug regimen to omit/replace thioguanines should be considered for children with MMR deficiency and/or reduced expression of key pathway components.
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