Persistent MRD before and after allogeneic BMT predicts relapse in children with acute lymphoblastic leukaemia

Minimal residual disease (MRD) during early chemotherapy is a powerful predictor of relapse in acute lymphoblastic leukaemia (ALL) and is used in children to determine eligibility for allogeneic haematopoietic stem cell transplantation (HSCT) in first (CR1) or later complete remission (CR2/CR3). Variables affecting HSCT outcome were analysed in 81 children from the ANZCHOG ALL8 trial. The major cause of treatment failure was relapse, with a cumulative incidence of relapse at 5 years (CIR) of 32% and treatment‐related mortality of 8%. Leukaemia‐free survival (LFS) and overall survival (OS) were similar for HSCT in CR1 (LFS 62%, OS 83%, n = 41) or CR2/CR3 (LFS 60%, OS 72%, n = 40). Patients achieving bone marrow MRD negativity pre‐HSCT had better outcomes (LFS 83%, OS 92%) than those with persistent MRD pre‐HSCT (LFS 41%, OS 64%, P < 0·0001) or post‐HSCT (LFS 35%, OS 55%, P < 0·0001). Patients with B‐other ALL had more relapses (CIR 50%, LFS 41%) than T‐ALL and the main precursor‐B subtypes including BCR‐ABL1, KMT2A (MLL), ETV6‐RUNX1 (TEL‐AML1) and hyperdiploidy >50. A Cox multivariate regression model for LFS retained both B‐other ALL subtype (hazard ratio 4·1, P = 0·0062) and MRD persistence post‐HSCT (hazard ratio 3·9, P = 0·0070) as independent adverse prognostic variables. Persistent MRD could be used to direct post‐HSCT therapy.     

Haploidentical transplantation compared with matched sibling and unrelated donor transplantation for adults with standard‐risk acute lymphoblastic leukaemia in first complete remission

We retrospectively investigated outcomes of haploidentical donor (HID) transplant for adults with standard‐risk acute lymphoblastic leukaemia (ALL) in first complete remission (CR1) compared with human leucocyte antigen (HLA)‐matched sibling donor (MSD) and HLA‐matched unrelated donor (MUD) transplants. A total of 348 adult patients were enrolled, including 127 HID, 144 MSD and 77 MUD recipients. The cumulative incidence of grade II–IV acute graft‐versus‐host disease (aGVHD) was 39·5%, 24·0% and 40·3% for HID, MSD and MUD, respectively (P = 0·020). However, there was no difference in grade III–IV aGVHD (11·4%, 7·7%, 13·5%, respectively, P = 0·468). The 5‐year cumulative transplant‐related mortality was 16·4%, 11·6% and 19·6% (P = 0·162), the 5‐year relapse rate post‐transplantation was 14·8%, 21·1% and 16·7% (P = 0·231), the 5‐year overall survival was 70·1%, 73·7% and 69·8% (P = 0·525), and the 5‐year disease‐free survival was 68·7%, 67·3% and 63·7%, respectively (P = 0·606). Furthermore, the 3‐year GVHD‐free, relapse‐free survival was not different (50·8%, 54·9% and 52·2%, respectively, P = 0·847). Our results indicate that the outcomes of HID transplants are equivalent to those of MSD and MUD, and that HID transplantation is a valid alternative for standard‐risk adults with ALL in CR1 who lack matched donors.     

Leukaemia relapse after allogeneic transplants for acute myeloid leukaemia: predictive role of WT1 expression

We assessed WT1 expression (expressed as messenger copies/10⁴ ABL1) from marrow cells of 122 patients with acute myeloid leukaemia (AML), before and after an unmanipulated allogeneic haemopoietic stem cell transplant (HSCT). The median age was 44 years (15–69), 59% were in first remission, 74% received a myeloablative conditioning regimen and the median follow up was 865 d (34–2833). Relapse was higher in 67 patients with WT1 expression, at any time post‐HSCT, exceeding 100 copies (54%), as compared to 16%, for 55 patients with post‐HSCT WT1 expression <100 copies (P < 0·0001). Similarly, actuarial 5‐year survival (OS) was 40% vs. 63%, respectively (P = 0·03). In multivariate Cox analysis, WT1 expression post‐HSCT was the strongest predictor of relapse (Hazard Ratio [HR] 4·5, P = 0·0001), independent of disease phase (HR 2·3, P = 0·002). Donor lymphocyte infusions (DLI) were given to 17 patients because of increasing WT1 levels: their OS was 44%, vs. 14% for 21 patients with increasing WT1 expression who did not receive DLI (P = 0·004). In conclusion, WT1 expression post‐HSCT is a strong predictor of leukaemia relapse and survival in AML; WT1 may be used as a marker for early interventional therapy.     

NOTCH1 mutations are associated with favourable long‐term prognosis in paediatric T‐cell acute lymphoblastic leukaemia: a retrospective study of patients treated on BCH‐2003 and CCLG‐2008 protocol in China

Activating mutations of NOTCH1 are a common occurrence in T‐cell acute lymphoblastic leukaemia (T‐ALL), but its impact on T‐ALL treatment is still controversial. In this study, the incidence, clinical features, and prognosis of 92 Chinese children with T‐ALL treated using the Beijing Children's Hospital‐2003 and Chinese Childhood Leukaemia Group‐2008 protocols were analysed. NOTCH1 mutations were found in 42% of T‐ALL patients and were not associated with clinical features, prednisone response, and minimal residual disease (MRD) at day 33 and 78. However, proline, glutamate, serine, threonine (PEST)/transactivation domain (TAD) mutations were associated with younger age (15/16 mutant vs. 48/76 wild‐type, P = 0·018) and more central nervous system involvement (4/16 mutant vs. 3/76 wild‐type, P = 0·016); while heterodimerization domain (HD) mutations were associated with KMT2A‐MLLT1 (MLL‐ENL; 4/30 mutant vs. 1/62 wild‐type, P = 0·037). Furthermore, prognosis was better in patients with NOTCH1 mutations than in those with wild‐type NOTCH1 (5‐year event‐free survival [EFS] 92·0 ± 4·5% vs. 64·0 ± 7·1%; P = 0·003). Long‐term outcome was better in patients carrying HD mutations than in patients with wild‐type HD (5‐year EFS 89·7 ± 5·6% vs. 69·3 ± 6·2%; P = 0·034). NOTCH1 mutations and MRD at day 78 were independent prognostic factors. These findings indicate that NOTCH1 mutation predicts a favourable outcome in Chinese paediatric patients with T‐ALL on the BCH‐2003 and CCLG‐2008 protocols, and may be considered a prognostic stratification factor.     

Improved outcome for children with non‐high risk acute lymphoblastic leukaemia after using an ALL IC‐BFM 2002‐based protocol in Shanghai,China

We report the outcome of 92 non‐high risk children with acute lymphoblastic leukaemia (ALL) following a Berlin‐Frankfürt‐Münster (BFM) Intercontinental ALL ‐based protocol. Compared with a matched historical control group, we found a lower incidence of treatment‐related early death (1·2% vs. 10·9%, P = 0·015), a higher 6‐year event‐free survival (75·4 ± 4·9% vs. 58·2 ± 6·7%, P = 0·02), reduced total in‐hospital costs per person (US $) (10267·0 vs. 18331·0, P < 0·001) and fewer total in‐hospital days (164 vs. 296, P < 0·001). This ALL‐BFM based protocol was quite tolerable in our institution and will be extended to high‐risk patients.     

Outcome of Down syndrome associated acute lymphoblastic leukaemia treated on a contemporary protocol

We report the outcome for children and young people with Down syndrome‐associated acute lymphoblastic leukaemia (DS‐ALL) treated on a contemporary protocol. Compared with non‐DS ALL, patients with DS‐ALL had an inferior event‐free survival (65·6% vs. 87·7% at 5 years; P < 0·00005) and overall survival (70·0% vs. 92·2%; P < 0·00005). Excess treatment‐related mortality – was primarily responsible for the worse outcomes for DS‐ALL (21·6% at 5 years, vs. 3·3%, P < 0·00005). Minimal residual disease (MRD) risk status was highly discriminant for relapse in DS patients with 0/28 relapses in the MRD low risk group.     

Clinical characteristics and outcomes in patients with acute promyelocytic leukaemia and hyperleucocytosis

The clinical characteristics, treatment options and outcomes in patients with acute promyelocytic leukaemia (APL) and hyperleucocytosis remain poorly defined. This study reviewed 242 consecutive patients with APL; 29 patients (12%) had a white blood cell count (WBC) ≥ 50 × 10⁹/l at presentation (median WBC 85·5 × 10⁹/l). Patients with hyperleucocytosis had inferior complete remission (CR) rates (69% vs. 88%; P = 0·004) and higher 4‐week mortality (24% vs. 9%; P = 0·018) compared to patients without hyperleucocytosis. We noted a trend towards inferior 3‐year disease‐free survival (DFS) (69% vs. 80%; P = 0·057) and inferior 3‐year overall survival (OS) (74% vs. 92%; P = 0·2) for patients with hyperleucocytosis. Leukapheresis was performed in 11 (38%) of the 29 patients with hyperleucocytosis. CR rate and 3‐year OS were not significantly improved in patients who received leukapheresis. CR rate and 3‐year OS for the 15 patients with hyperleucocytosis treated with all‐trans retinoic acid (ATRA) plus arsenic trioxide (ATO) plus cytotoxic therapy (idarubicin or gemtuzumab ozogamicin) combinations were 100% and 100% vs. 57% and 35% for the 14 patients treated with non‐ATRA/ATO combinations (P = 0·004 and P = 0·002). Leukapheresis does not improve the outcomes in patients with APL presenting with hyperleucocytosis. ATRA/ATO‐based combinations are superior to other regimens in these patients.     

Long-term outcome evaluation of medium/high risk acute lymphoblastic leukaemia children treated with or without cranial radiotherapy in the EORTC 58832 randomized study

We investigated the long-term outcome, the incidence of second neoplasms (SN) and the rate of late adverse effects (LAE) in children with central nervous system (CNS) negative medium/high-risk de novo acute lymphoblastic leukaemia (ALL), in first complete remission (CR1) at end of late intensification, randomized to receive no cranial radiotherapy (No CRT, n = 92) versus CRT (standard arm, n = 84) in the non-inferiority EORTC 58832 study (1983–1989). Median follow-up was 20 years (range 4–32 years). The 25-year disease-free survival rate (±SE) was 67·4 ± 4·9% without CRT and 70·2 ± 5·0% with CRT. The 25-year incidence of isolated (6·5 ± 2·6% vs. 4·8 ± 2·3%) and any CNS relapse {8·7 ± 2·9% vs. 11·9 ± 3·5%; hazard ratio (HR) 0·71 [95% confidence interval (CI) 0·28–1·79]; test of non-inferiority: P = 0·01} was not increased without CRT. The 25-year SN incidence in CR1 was 7·9 ± 4·6% vs. 11·0 ± 4·2%. The 25-year event-free and overall survival rates were quite similar in both arms [59·5 ± 6·3% vs. 60·5 ± 5·9%, HR 0·94 (95% CI 0·57–1·52), and 78·1 ± 4·3% vs. 78·5 ± 4·5%, HR 1·00 (95% CI 0·53–1·88)]. Omission of CRT was associated with dramatic decrease in CNS and endocrine LAE rates. In conclusion, our data suggest that, with proper systemic and intrathecal CNS prophylaxis, CRT could totally be omitted in CR1 without jeopardizing survival, while decreasing LAE in childhood ALL.     

Clinical relevance of molecular aberrations in paediatric acute myeloid leukaemia at first relapse

Outcome for relapsed paediatric acute myeloid leukaemia (AML) remains poor. Strong prognostic factors at first relapse are lacking, which hampers optimization of therapy. We assessed the frequency of molecular aberrations (FLT3, NRAS, KRAS, KIT, WT1 and NPM1 genes) at first relapse in a large set (n = 198) of relapsed non‐French‐American‐British M3, non‐Down syndrome AML patients that received similar relapse treatment. We correlated molecular aberrations with clinical and biological factors and studied their prognostic relevance. Hotspot mutations in the analysed genes were detected in 92 out of 198 patients (46·5%). In 72 of these 92 patients (78%), molecular aberrations were mutually exclusive for the currently analysed genes. FLT3‐internal tandem repeat (ITD) (18% of total group) mutations were most frequent, followed by NRAS (10·2%), KRAS (8%), WT1 (8%), KIT (8%), NPM1 (5%) and FLT3‐tyrosine kinase domain (3%) mutations. Presence of a WT1 aberration was an independent risk factor for second relapse (Hazard Ratio [HR] = 2·74, P = 0·013). In patients who achieved second complete remission (70·2%), WT1 and FLT3‐ITD aberrations were independent risk factors for poor overall survival (HR = 2·32, P = 0·038 and HR = 1·89, P = 0·045 respectively). These data show that molecular aberrations at first relapse are of prognostic relevance and potentially useful for risk group stratification of paediatric relapsed AML and for identification of patients eligible for personalized treatment.     

Rituximab maintenance improves survival in male patients with diffuse large B‐cell lymphoma. Results of the HD2002 prospective multicentre randomized phase III trial

In the multicentre prospective randomized HD2002 trial, rituximab maintenance therapy (375 mg/m² every 3 months for 2 years) versus observation was evaluated for CD20⁺ B‐cell lymphoma. Out of 321 patients [161 randomized to the treatment group (TG), 160 to the observation group (OG)], 295 data sets were evaluable for statistical analysis. Estimated 5‐year relapse‐free survival (RFS) was 81% in the TG and 70% in the OG (logrank test, P = 0·047). In the diffuse large B‐cell lymphoma (DLBCL) subgroup (n = 152), 5‐year RFS was excellent, at 87% in the TG and 84% in the OG (logrank test, P = 0·35). Of note, only in male patients of the DLBCL subgroup was RFS significantly superior in the TG in comparison to the OG (5‐year RFS: 88% vs. 74%; logrank test, P = 0·05). Cox regression analysis showed a significant interaction between treatment and gender regarding overall survival (OS) (P = 0·006) and RFS (P = 0·02), with a lower hazard in females than males in the OG [OS: hazard ratio (HR) (female:male) = 0·11; 95% confidence interval (CI) = 0·00–1·03; RFS: HR (female:male) = 0·27; 95% CI = 0·05–0·97], and no significant differences between males and females in the TG. We conclude that Rituximab maintenance therapy improves survival in male patients with DLBCL.     

Outcome for children and young people with Early T‐cell precursor acute lymphoblastic leukaemia treated on a contemporary protocol,UKALL 2003

We investigated the outcome for children and young people with Early T‐precursor acute lymphoblastic leukaemia (ETP‐ALL), a recently described poor prognosis sub‐group of T‐ALL, treated on a contemporary protocol, UKALL 2003. After a median follow‐up of 4 years and 10 months, the ETP sub‐group, representing 16% of T‐ALL patients, had non‐significantly inferior 5‐year event‐free survival (76·7% vs. 84·6%, P = 0·2) and overall survival (82·4% vs. 90·9%, P = 0·1), and a higher relapse rate (18·6% vs. 9·6%, P = 0·1) compared to typical T‐ALL. ETP‐ALL has an intermediate risk outcome, which does not warrant experimental treatment or first remission allogeneic transplant for the group universally.     

CD49d associates with nodal presentation and subsequent development of lymphadenopathy in patients with chronic lymphocytic leukaemia

CD 49d is a surface integrin that is expressed on chronic lymphocytic leukaemia (CLL ) cells, and strongly correlates with more aggressive disease. Given its association with cell‐cell adhesion and leucocyte trafficking, we hypothesized that patients with high CD 49d expression would experience a clinical course dominated by lymphadenopathy. CD 49d expression was measured by flow cytometry and considered positive if expressed by ≥30% of CLL cells. The study included 797 newly diagnosed CLL /small lymphocytic leukaemia patients; 279 (35%) were CD 49d positive. CD 49d‐positive patients were more likely to present with lymphadenopathy (P  <  0·001); a finding that persisted after adjusting for fluorescence in situ hybridisation (FISH ) and IGHV mutation status [odds ratio (OR ) 2·51; 95% confidence interval (CI ) 1·64–3·83; P  <  0·001]. Among CLL Rai 0 patients, CD 49d positivity was associated with shorter time to development of lymphadenopathy (3·2 years vs not reached, P  <  0·01). This association was maintained after adjusting for either FISH [hazard ratio (HR ) 2·18; 95% CI 1·25–3·81; P  =  0·006) or IGHV status (HR 2·02; 95% CI 1·11–3·69; P  =  0·02) individually, but was attenuated when adjusting by both (HR 1·72; 95% CI 0·88–3·38; P  =  0·11).These data demonstrate that CD 49d‐positive CLL patients experience a disease course dominated by lymphadenopathy. These findings could have implications for therapy selection and disease monitoring.     

Phase 2 study of tabalumab,a human anti‐B‐cell activating factor antibody,with bortezomib and dexamethasone in patients with previously treated multiple myeloma

In this double‐blind, Phase 2 study, 220 patients with relapsed/refractory multiple myeloma were randomly assigned 1:1:1 to receive placebo (N  = 72), tabalumab 100 mg (N  = 74), or tabalumab 300 mg (N  = 74), each in combination with dexamethasone 20 mg and subcutaneous bortezomib 1·3 mg/m² on a 21‐day cycle. No significant intergroup differences were observed among primary (median progression‐free survival [mPFS ]) or secondary efficacy outcomes. The mPFS was 6·6, 7·5 and 7·6 months for the tabalumab 100, 300 mg and placebo groups, respectively (tabalumab 100 mg vs. placebo Hazard ratio (HR ) [95% confidence interval (CI )] = 1·13 [0·80–1·59], P  =  0·480; tabalumab 300 mg vs. placebo HR [95% CI ] = 1·03 [0·72–1·45], P  =  0·884). The most commonly‐reported treatment‐emergent adverse events were thrombocytopenia (37%), fatigue (37%), diarrhoea (35%) and constipation (32%). Across treatments, patients with low baseline BAFF (also termed TNFSF 13B) expression (n  = 162) had significantly longer mPFS than those with high BAFF expression (n  = 55), using the 75th percentile cut‐off point (mPFS [95% CI ] = 8·3 [7·0–9·3] months vs. 5·8 [3·7–6·6] months; HR [95% CI ] = 1·59 [1·11–2·29], P  =  0·015). Although generally well tolerated, PFS was not improved during treatment with tabalumab compared to placebo. A higher dose of 300 mg tabalumab did not improve efficacy compared to the 100 mg dose. Nonetheless, BAFF appears to have some prognostic value in patients with multiple myeloma.     

The distribution of MLL breakpoints correlates with outcome in infant acute leukaemia

Acute leukaemia in early childhood ‐ and mainly infant leukaemia (IL) – is characterized by acquired genetic alterations, most commonly by the presence of distinct MLL rearrangements (MLL‐r). The aim of this study was to investigate possible correlations between clinical features and molecular analyses of a series of 545 childhood leukaemia (≤24 months of age) cases: 385 acute lymphoblastic leukaemia (ALL) and 160 acute myeloid leukaemia (AML). The location of the genomic breakpoints was determined in a subset of 30 MLL‐r cases. The overall survival of the investigated cohort was 60·5%, as determined by the Kaplan‐Meier method. Worse outcomes were associated with age at diagnosis ≤6 months (P < 0·001), high white blood cell count (P = 0·001), and MLL‐r (P = 0·002) in ALL, while children with AML displayed a poorer outcome (P = 0·009) regardless of their age strata. Moreover, we present first evidence that MLL‐r patients with poor outcome preferentially displayed chromosomal breakpoints within MLL intron 11. Based on the literature, most MLL‐r IL display a breakpoint localization towards intron 11, which in turn may explain their worse clinical course. In summary, the MLL breakpoint localization is of clinical importance and should be considered as a novel outcome predictor for MLL‐r patients.     

Prognostic impact of KMT2E transcript levels on outcome of patients with acute promyelocytic leukaemia treated with all‐trans retinoic acid and anthracycline‐based chemotherapy: an International Consortium on Acute Promyelocytic Leukaemia study

The KMT2E (MLL5) gene encodes a histone methyltransferase implicated in the positive control of genes related to haematopoiesis. Its close relationship with retinoic acid–induced granulopoiesis suggests that the deregulated expression of KMT2E might lead acute promyelocytic leukaemia (APL) blasts to become less susceptible to the conventional treatment protocols. Here, we assessed the impact of KMT2E expression on the prognosis of 121 APL patients treated with ATRA and anthracycline‐based chemotherapy. Univariate analysis showed that complete remission (P = 0·006), 2‐year overall survival (OS) (P = 0·005) and 2‐year disease‐free survival (DFS) rates (P = 0·037) were significantly lower in patients with low KMT2E expression; additionally, the 2‐year cumulative incidence of relapse was higher in patients with low KMT2E expression (P = 0·04). Multivariate analysis revealed that low KMT2E expression was independently associated with lower remission rate (odds ratio [OR]: 7·18, 95% confidence interval [CI]: 1·71–30·1; P = 0·007) and shorter OS (hazard ratio [HR]: 0·27, 95% CI: 0·08–0·87; P = 0·029). Evaluated as a continuous variable, KMT2E expression retained association with poor remission rate (OR: 10·3, 95% CI: 2·49–43·2; P = 0·001) and shorter survival (HR: 0·17, 95% IC: 0·05–0·53; P = 0·002), while the association with DFS was of marginal significance (HR: 1·01; 95% CI: 0·99–1·02; P = 0·06). In summary, low KMT2E expression may predict poor outcome in APL patients.     

Thrombophilia screening and thromboprophylaxis may benefit specific ethnic subgroups with paediatric acute lymphoblastic leukaemia

This study investigated the prevalence of inherited thrombophilia, risk of venous thromboembolism (VTE) and benefit of low molecular weight heparin prophylaxis in 476 Israeli children with acute lymphoblastic leukaemia (ALL) treated between 2004 and 2016. Thrombophilia was found in 15·5%. Arab children had a higher prevalence of F5 R506Q (factor V Leiden) than Jewish children (19·4% vs. 2·9%, P < 0·01). Patients with thrombophilia had higher VTE rates VTE (26·5% vs. 5·6%, P < 0·001). None of the thrombophilic children given prophylaxis had severe VTE. Routine evaluation for inherited thrombophilia followed by thromboprophylaxis when findings are positive may benefit at-risk patients with ALL.     

Thiopurine dose intensity and treatment outcome in childhood lymphoblastic leukaemia: the influence of thiopurine methyltransferase pharmacogenetics

The impact of thiopurine methyltransferase (TPMT) genotype on thiopurine dose intensity, myelosuppression and treatment outcome was investigated in the United Kingdom childhood acute lymphoblastic leukaemia (ALL) trial ALL97. TPMT heterozygotes had significantly more frequent cytopenias and therefore required dose adjustments below target levels significantly more often than TPMT wild‐type patients although the average dose range was similar for both genotypes. Event‐free survival (EFS) for patients heterozygous for the more common TPMT*1/*3A variant allele (n = 99, 5‐year EFS 88%) was better than for both wild‐type TPMT*1/*1 (n = 1206, EFS 80%, P = 0·05) and TPMT*1/*3C patients (n = 17, EFS 53%, P = 0·002); outcomes supported by a multivariate Cox regression analysis. Poor compliance without subsequent clinician intervention was associated with a worse EFS (P = 0·02) and such non‐compliance may have contributed to the poorer outcome for TPMT*1/*3C patients. Patients prescribed escalated doses had a worse EFS (P = 0·04), but there was no difference in EFS by dose intensity or duration of cytopenias. In contrast to reports from some USA and Nordic trials, TPMT heterozygosity was not associated with a higher rate of second cancers. In conclusion, TPMT*1/*3A heterozygotes had a better EFS than TPMT wild‐type patients. Thiopurine induced cytopenias were not detrimental to treatment outcome.     

Rapid identification of BCR/ABL1‐like acute lymphoblastic leukaemia patients using a predictive statistical model based on quantitative real time‐polymerase chain reaction: clinical,prognostic and therapeutic implications

BCR/ABL1‐like acute lymphoblastic leukaemia (ALL) is a subgroup of B‐lineage acute lymphoblastic leukaemia that occurs within cases without recurrent molecular rearrangements. Gene expression profiling (GEP) can identify these cases but it is expensive and not widely available. Using GEP, we identified 10 genes specifically overexpressed by BCR/ABL1‐like ALL cases and used their expression values – assessed by quantitative real time‐polymerase chain reaction (Q‐RT‐PCR) in 26 BCR/ABL1‐like and 26 non‐BCR/ABL1‐like cases to build a statistical “BCR/ABL1‐like predictor”, for the identification of BCR/ABL1‐like cases. By screening 142 B‐lineage ALL patients with the “BCR/ABL1‐like predictor”, we identified 28/142 BCR/ABL1‐like patients (19·7%). Overall, BCR/ABL1‐like cases were enriched in JAK/STAT mutations (P < 0·001), IKZF1 deletions (P < 0·001) and rearrangements involving cytokine receptors and tyrosine kinases (P = 0·001), thus corroborating the validity of the prediction. Clinically, the BCR/ABL1‐like cases identified by the BCR/ABL1‐like predictor achieved a lower rate of complete remission (P = 0·014) and a worse event‐free survival (P = 0·0009) compared to non‐BCR/ABL1‐like ALL. Consistently, primary cells from BCR/ABL1‐like cases responded in vitro to ponatinib. We propose a simple tool based on Q‐RT‐PCR and a statistical model that is capable of easily, quickly and reliably identifying BCR/ABL1‐like ALL cases at diagnosis.     

Low burden of minimal residual disease prior to transplantation in children with very high risk acute lymphoblastic leukaemia: The NOPHO ALL2008 experience

The population-based Nordic/Baltic acute lymphoblastic leukaemia (ALL) Nordic Society for Paediatric Haematology and Oncology (NOPHO) ALL2008 protocol combined minimal residual disease (MRD)-driven treatment stratification with very intense first line chemotherapy for patients with high risk ALL. Patients with MRD ≥5% at end of induction or ≥10⁻³ at end of consolidation or following two high risk blocks were eligible for haematopoietic cell transplantation (HCT) in first remission. After at least three high risk blocks a total of 71 children received HCT, of which 46 had MRD ≥5% at end of induction. Ten patients stratified to HCT were not transplanted; 12 received HCT without protocol indication. Among 69 patients with evaluable pre-HCT MRD results, 22 were MRD-positive, one with MRD ≥10⁻³. After a median follow-up of 5·5 years, the cumulative incidence of relapse was 23·5% (95% confidence interval [CI]: 10·5–47·7) for MRD-positive versus 5·1% (95% CI: 1·3–19·2), P = 0·02) for MRD-negative patients. MRD was the only variable significantly associated with relapse (hazard ratio 9·1, 95% CI: 1·6–51·0, P = 0·012). Non-relapse mortality did not differ between the two groups, resulting in disease-free survival of 85·6% (95% CI: 75·4–97·2) and 67·4% (95% CI: 50·2–90·5), respectively. In conclusion, NOPHO block treatment efficiently reduced residual leukaemia which, combined with modern transplant procedures, provided high survival rates, also among pre-HCT MRD-positive patients.     

Identification of relapse-associated gene mutations by next-generation sequencing in low-risk acute myeloid leukaemia patients

Recommended genetic categorization of acute myeloid leukaemias (AML) includes a favourable-risk category, but not all these patients have good prognosis. Here, we used next-generation sequencing to evaluate the mutational profile of 166 low-risk AML patients: 30 core-binding factor (CBF)-AMLs, 33 nucleophosmin (NPM1)-AMLs, 4 biCEBPα-AMLs and 101 acute promyelocytic leukaemias (APLs). Functional categories of mutated genes differed among subgroups. NPM1-AMLs showed frequent variations in DNA-methylation genes (DNMT3A, TET2, IDH1/2) (79%), although without prognostic impact. Within this group, splicing-gene mutations were an independent factor for relapse-free (RFS) and overall survival (OS). In CBF-AML, poor independent factors for RFS and OS were mutations in RAS pathway and cohesin genes, respectively. In APL, the mutational profile differed according to the risk groups. High-risk APLs showed a high mutation rate in cell-signalling genes (P = 0·002), highlighting an increased incidence of FLT3 internal tandem duplication (ITD) (65%, P < 0·0001). Remarkably, in low-risk APLs (n = 28), NRAS mutations were strongly correlated with a shorter five-year RFS (25% vs. 100%, P < 0·0001). Overall, a high number of mutations (≥3) was the worst prognostic factor RFS (HR = 2·6, P = 0·003). These results suggest that gene mutations may identify conventional low-risk AML patients with poor prognosis and might be useful for better risk stratification and treatment decisions.