A novel high-precision fiber tractography for nuclear localization in transcranial magnetic resonance-guided focused ultrasound surgery: a pilot study.

OBJECTIVE: In transcranial MR-guided focused ultrasound (TcMRgFUS), fiber tractography using diffusion tensor imaging (DTI) has been proposed as a direct method to identify the ventral intermediate nucleus (Vim), the ventral caudal nucleus (Vc), and the pyramidal tract (PT). However, the limitations of the DTI algorithm affect the accuracy of visualizing anatomical structures due to its low-quality fiber tractography, whereas the application of the generalized q-sampling imaging (GQI) algorithm enables the visualization of high-quality fiber tracts, offering detailed insights into the spatial distribution of motor cortex fibers. This retrospective study aimed to investigate the usefulness of high-precision fiber tractography using the GQI algorithm as a planning image in TcMRgFUS to achieve favorable clinical outcomes. METHODS: This study included 20 patients who underwent TcMRgFUS. The Clinical Rating Scale for Tremor (CRST) scores and MR images were evaluated pretreatment and at 24 hours and 3-6 months after treatment. Cases were classified based on the presence and adversity of adverse events (AEs): no AEs, mild AEs without additional treatment, and severe AEs requiring prolonged hospitalization. Fiber tractography of the Vim, Vc, and PT was visualized using the DTI and GQI algorithm. The overlapping volume between Vim fibers and the lesion was measured, and correlation analysis was performed. The relationship between AEs and the overlapping volume of the Vc and PT fibers within the lesions was examined. The cutoff value to achieve a favorable clinical outcome and avoid AEs was determined using receiver operating characteristic curve analysis. RESULTS: All patients showed improvement in tremors 24 hours after treatment, with 3 patients experiencing mild AEs and 1 patient experiencing severe AEs. At the 3- to 6-month follow-up, 5 patients experienced recurrence, and 2 patients had persistent mild AEs. Although fiber visualization in the motor cortex using the DTI algorithm was insufficient, the GQI algorithm enabled the visualization of significantly higher-quality fibers. A strong correlation was observed between the overlapping volume that intersects the lesion and Vim fibers and the degree of tremor improvement (r = 0.72). Higher overlapping volumes of Vc and PT within the lesion were associated with an increased likelihood of AEs (p < 0.05); the cutoff volume of Vim fibers within the lesion for a favorable clinical outcome was 401 mm3, while the volume of Vc and PT within the lesion to avoid AEs was 99 mm3. CONCLUSIONS: This pilot study suggests that incorporating the high-precision GQI algorithm for fiber tractography as a planning imaging technique for TcMRgFUS has the potential to enhance targeting precision and achieve favorable clinical outcomes.

Current Challenges of Asian National Children's Cancer Study Groups on Behalf of Asian Pediatric Hematology and Oncology Group.

In Asia, a few countries have a long and established history of collaborative clinical trials successfully formed national children's cancer study groups, but many still do not have such groups. The process of forming national children's cancer groups is fraught with many hurdles, which varies among the countries. One of the basic requirements for running clinical trials is an affordable health care system in which most of the children with cancer can receive the proposed treatment. The health insurance coverage for children with cancer varies from <20% to as high as 100% among Asian countries, and the operation of clinical trials must also be adjusted accordingly. Shortage of research personnel is common, including medical, nursing, research coordinators, and data managers. The establishment of the Asian Pediatric Hematology and Oncology Group aims to provide a good platform for promotion of international clinical trials in the Asian countries.

Outcome of hematopoietic stem cell transplantation in pediatric patients with acute lymphoblastic leukemia not in remission enrolled in JACLS ALL-02.

Hematopoietic stem cell transplantation (HSCT) is only indicated for acute lymphoblastic leukemia (ALL) patients for whom other treatments are unlikely to be curative. However, outcomes of patients not in complete remission (CR) at HSCT remain very poor. To improve the outcomes of patients receiving HSCT, it is important to obtain detailed clinical information about patients with ALL receiving HSCT in CR and not in CR. Patients enrolled in the Japan Association of Childhood Leukemia Study ALL-02 who underwent HSCT and were not in CR (non-CR patients, n = 55) were examined. The 1-year overall survival (OS) rate of non-CR patients was 27.3%. Compared with CR patients, non-CR patients experienced very early and early relapse significantly more frequently and had poorer prognostic factors. Most interestingly, high hyperdiploid (HHD) patients showed an excellent 1-year OS of 80%. In addition, long-term survival among surviving HHD patients was longer than 5 years. All eight patients who survived after undergoing HSCT while not in CR were younger than 10 years at initial diagnosis and were negative for central nervous system involvement. While limited, these results suggest that a subset of patients may benefit from HSCT while not in CR.

Improvement in Intraoperative Image Quality in Transcranial Magnetic Resonance-Guided Focused Ultrasound Surgery Using Transmitter Gain Adjustment.

INTRODUCTION: Transcranial magnetic resonance-guided focused ultrasound surgery (TcMRgFUS) has the advantage of allowing immediate evaluation of therapeutic effects after each sonication and intraoperative magnetic resonance imaging (MRI) to visualize the lesion. When the image shows that the lesion has missed the planned target and the therapeutic effects are insufficient, the target of the subsequent ablation can be finely adjusted based on the image. The precision of this adjustment is determined by the image quality. However, the current intraoperative image quality with a 3.0T MRI system is insufficient for precisely detecting the lesion. Thus, we developed and validated a method for improving intraoperative image quality. METHODS: Because intraoperative image quality is affected by transmitter gain (TG), we acquired T2-weighted images (T2WIs) with two types of TG: the automatically adjusted TG (auto TG) and the manually adjusted TG (manual TG). To evaluate the character of images with 2 TGs, the actual flip angle (FA), the image uniformity, and the signal-to-noise ratio (SNR) were measured using a phantom. Then, to assess the quality of intraoperative images, T2WIs with both TGs were acquired during TcMRgFUS for 5 patients. The contrast-to-noise ratio (CNR) of the lesion was retrospectively estimated. RESULTS: The images of the phantom with the auto TG showed substantial variations between the preset and actual FAs (p < 0.01), whereas on the images with the manual TG, there were no variations between the two FAs (p > 0.05). The total image uniformity was considerably lower with the manual TG than with the auto TG (p < 0.01), indicating that the image's signal values with the manual TG were more uniform. The manual TG produced significantly higher SNRs than the auto TG (p < 0.01). In the clinical study, the lesions were clearly detected in intraoperative images with the manual TG, but they were difficult to identify in images with the auto TG. The CNR of lesions in images with manual TG was considerably higher than in images with auto TG (p < 0.01). CONCLUSION: Regarding intraoperative T2WIs using a 3.0T MRI system during TcMRgFUS, the manual TG method improved image quality and delineated the ablative lesion more clearly than the current method with auto TG.

Psychological characteristics of Japanese patients and their family members receiving genetic counseling: A single-institute exploratory study.

In Japan, clinical genetic services became available in the 1970s, and genomic medicine, including genetic counseling (GC), developed rapidly. However, research on the outcomes of GC in Japan is limited. Japan has a unique cultural context, and appropriate GC methods have not yet been optimized for this population. The current study aimed to evaluate the psychological status of Japanese patients and their companions undergoing GC and the outcomes of GC. We used the Quality of Care Through the Patients' Eyes-gene cancer (QUOTE-geneCA ), the Genetic Counseling Outcome Scale-24 (GCOS-24), and the State-Trait Anxiety Inventory (STAI) to evaluate patients and their companions' needs and preferences regarding GC, empowerment, and anxiety, respectively. We evaluated stress status during GC by measuring saliva cortisol levels. QUOTE-geneCA results for patients (n = 69) and a group of patients and their companions (n = 96) revealed that participants felt that it was important that skilled medical staff explained medical information and provided advice in an easily understandable manner. Japanese patients and their companions regarded the procedural aspects of counseling as most important and their autonomy in decision-making as less important. GCOS-24 results revealed a significant increase in empowerment scores in 38 patients (by 9.63 points) from pre- to post-GC (p < 0.001; Cohen's d = 0.79). STAI results revealed a significant decrease in state anxiety for patients (6.11 points; p < 0.001; Cohen's d = 0.66). Cortisol levels in patients significantly decreased after GC (p = 0.001). The improvement of empowerment scores from pre- to post-GC among patients and their companions were significantly negatively correlated with pre-GC empowerment scores (p < 0.001), trait anxiety scores (p = 0.001), and the number of people living together (p = 0.011). The change of cortisol levels during GC in patients and their companions was significantly positively correlated with trait anxiety score (p = 0.027). This study suggested that these characteristics of Japanese patients and their companions may predict GC outcomes.

[Investigation of Changing Imaging Contrast Using Compressed Sensing in Gd-EOB-DTPA Hepatocyte Phase].

In recent years, gadolinium ethoxybenzyl diethylenetriamine pantaacetic acid (Gd-EOB-DTPA) has been commonly used in magnetic resonance imaging (MRI) for liver contrast studies. The purpose of this study was to investigate the effect of Hyper SENSE factor on contrast in the Gd-EOB-DTPA hepatocyte phase. The subjects were 21 patients [16 males and 5 females, aged 50-94 years (mean age 68±12years)] who underwent hepatic contrast-enhanced MRI with Gd-EOB-DTPA from March 2021 to December 2021. The contrast ratios (CRs) of liver/spleen and liver/tumor were measured when the Hyper SENSE factor was changed to 1.0, 1.4 and 1.8. As a result, there was no statistically significant difference in signal intensity and CR with the change in the Hyper SENSE factor. In this study, the acquisition time can be shortened without decreasing the CR; therefore, it was suggested to improve MR images to avoid motion artifact.

JACLS ALL-02 SR protocol reduced-intensity chemotherapy produces excellent outcomes in patients with low-risk childhood acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. As overall cure rates of childhood ALL have improved, reduction of overall treatment intensity while still ensuring excellent outcomes is imperative for low-risk patients. We report the outcomes of patients treated following the standard-risk protocol from the prospective Japan Association of Childhood Leukemia Study (JACLS) ALL-02 study, which was conducted between 2002 and 2008 for patients with newly diagnosed ALL aged 1-18 years. Of 1138 patients with B-cell precursor ALL, 388 (34.1%) were allocated to this protocol. Excellent outcomes were achieved despite the overall treatment intensity being lower than that of most contemporary protocols: 4 years event-free survival (EFS) was 92.3% and 4 years overall survival 98.2%. Patients with high hyperdiploidy (HHD) involving triple trisomy (trisomy of chromosomes 4, 10, and 17) or ETV6-RUNX1 had even better outcomes (4 years EFS 97.6% and 100%, respectively). Unique characteristics of this protocol include a selection of low-risk patients with a low initial WBC count and good early treatment response and reduction of cumulative doses of chemotherapeutic agents while maintaining dose density. In Japan, we are currently investigating the feasibility of this protocol while incorporating minimal residual disease into the patient stratification strategy.

A pilot study of game-based learning programs for childhood cancer survivors.

BACKGROUND: Childhood cancer survivors lacking awareness on their potential risks of late effects often fail to seek adequate follow-up care. Patient education matching their preference is of great importance to improve their adherence to survivorship care. In this study, we developed two age-dependent game-based learning programs, which enable continuous approaches for childhood cancer survivors along their intellectual maturation. Then, we assessed the effectiveness of the programs. METHODS: Childhood cancer survivors over 10 years of age who regularly visited a long-term follow-up clinic were enrolled in this study. They were requested to play either of two different types of game tools, one for school children and another for adolescents and young adults, for one month at home. To evaluate the educational effects of the programs, they were examined for health management awareness, self-esteem, and knowledge on cancer-related late effects before and after the intervention with age-based questionnaires and knowledge tests. RESULTS: Among 83 participants, 49 (59.0%) completed the assessments over the period of 12 months. The health management awareness and knowledge levels increased significantly at 1-month after the intervention as compared to the baseline in both school children and adolescents/young adults (for health management awareness, p = 0.011 in elementary school children; p = 0.007 in junior high school children; p < 0.001 in adolescents/young adults; for knowledge levels, p < 0.001 in school children; p < 0.001 in adolescents/young adults). The effect was maintained for 12 months in school children while it decreased in adolescents and young adults with time. Self-esteem significantly increased at 1-month (p = 0.002 in school children; p = 0.020 in adolescents/young adults) and was maintained for 12 months in both age groups. CONCLUSION: The game-based learning programs enhanced health locus of control and self-esteem in childhood cancer survivors. The game-based learning programs could be applied effectively to survivorship care as a new modality of patient education. TRIAL REGISTRATION: This study was retrospectively registered in UMIN-CTR ( UMIN000043603 ) on March 12, 2021.

Change in children's perception of cancer in the last 10 years in Japan.

BACKGROUND: Social awareness of cancer can be changed with cancer education and proper distribution of cancer information. This study addressed the current situation and historical changes to children's perception of cancer. METHODS: Questionnaire surveys were conducted among healthy school children aged 10-15 years in 2008 and 2018. Knowledge of cancer was surveyed and compared with that of asthma, tuberculosis, and measles. The children were asked about their health information resources. RESULTS: The numbers of participants and collection rates were 438 and 63.9% in 2008, and 320 and 44.7% in 2018. Children's perception of cancer changed significantly in the last decade. The proportion of respondents answering "cancer affects children" changed from 78.3 to 89.5% (P = 0.0001), "cancer is preventable" from 42.0 to 49.7% (P = 0.0425), and "cancer is curable," from 52.4 to 66.0% (P = 0.0003). Significantly more junior high school students answered that cancer is preventable than elementary school children in 2018 (55.9 vs 42.7%, P = 0.0028). The major resources of information on health were television, parents, and books. The proportion of children choosing the Internet significantly increased from 15.3 to 47.8% (P < 0.0001). Significantly more junior high school students selected television and the Internet than elementary school children (94.5 vs 86.9%, P = 0.0202 for television; 57.1 vs 37.9%, P = 0.0007 for the Internet). CONCLUSIONS: The proportion of children correctly perceiving cancer information had increased in the last decade. Junior high school students better understood the information. The Internet is of increasing importance as an information resource for school children.

Changes of cancer diagnosis disclosure to children in Japan in the last 20 years.

BACKGROUND: The practice of cancer diagnosis disclosure to children has been changed with the times. The regulations of clinical trials in the 2000s might change the practice in Japan. However, the perspective of this topic among children and adults has not been investigated in detail. METHODS: We studied changes in the practice of information sharing with children with cancer at pediatric cancer centers and the perspective of cancer diagnosis disclosure to children among school children, their parents and pediatric oncologists in the last 20 years by comparing the results of questionnaire surveys conducted in 1998, 2008 and 2018. RESULTS: This study revealed that the performing rate has increased with the times, but the institutions actively performing for children aged 7-9 years were 36.4% even in the 2018 survey. More than 70% of children wished diagnosis disclosure if they suffer from cancer in the series of surveys, while the ratio of parents who tell cancer diagnosis to their children hovered at 34.5 to 53.7% (p < 0.001 in all surveys). The ratio of pediatric oncologists having the policy to perform diagnosis disclosure proactively increased from 9.3 to 60.0%, while that of parents having the same policy stayed at 5.3% even in 2018. CONCLUSIONS: The performing rate of information sharing with children with cancer was significantly changed in the last 20 years. The opinion gaps were observed between parents and children and between parents and pediatric oncologists.

CD56-positive Angioimmunoblastic T-cell Lymphoma Complicated by Chylothorax.

A 77-year-old woman presented with systemic lymphadenopathy and bilateral pleural effusion. Angioimmunoblastic T-cell lymphoma (AITL) was diagnosed based on the results of a lymph node biopsy. AITL cells expressed the aberrant antigen of CD56. The bilateral pleural effusion was attributed to chylothorax, not the infiltration of lymphoma cells into the pleura, as determined by the pleural fluid analysis. We therefore diagnosed her with CD56-positive AITL complicated by chylothorax. She achieved complete remission by multidrug chemotherapy. AITL is commonly complicated by pleural effusion, but rarely by chylothorax. This is the first case of CD56-positive AITL complicated by chylothorax.

Impact of a multi-professional expert team on EOL care of children with cancer.

BACKGROUND: The quality of end-of-life (Q-EOL) care is influenced by various factors such as resources for palliative care (PC). We introduced a multi-professional expert team (MET) in 2014, which provides home-based care for children and adolescents with incurable cancer. This study investigated the impacts of the outreach activities by the MET on Q-EOL care of pediatric oncology patients. METHODS: This observational study retrospectively examined 112 patients receiving end-of-life care between 1989 and 2018 at a pediatric cancer center in Japan. Some of the indicators of Q-EOL care before and after the introduction of the outreach activities by the MET were compared. The subjects were 92 in pre-MET and 20 in post-MET periods. RESULTS: The median number of days for which the patients stayed at home during the final seven or 30 days were significantly prolonged in the post-MET period (0.0 vs 1.5 days, P = 0.020, 3.0 vs 12.0 days, P = 0.042). The change was more significant in hematologic malignancies than solid and central nervous system tumors. Patients receiving longer PC before their deaths could stay at home longer during the last 7 days. The ratio of patients receiving PC for more than 2 months was significantly increased in post-MET period (60.9 vs 90.0%, P = 0.014). More patients also greeted their deaths at home in the post-MET period (3.3 vs 25.0%, P < 0.001). CONCLUSIONS: The activities of the MET transformed the end-of-life care of children and adolescents with incurable cancer. Earlier transitions to PC from curative treatment were associated with longer home-based care and more deaths at home.

Prednisolone poor response is not an indication for HSCT in pediatric B-cell precursor acute lymphoblastic leukemia in first remission: results from JACLS ALL-02 study.

Approximately 90% of pediatric acute lymphoblastic leukemia (ALL) cases are curable with intensified chemotherapy, but very high-risk patients may require hematopoietic stem cell transplantation (HSCT). A suitable indication for HSCT in the first complete remission (CR1) should be defined to protect patients from long-term complications. We report the outcomes of HSCT in CR1 from the Japan Association of Childhood Leukemia Study (JACLS) ALL-02 study and reassess indications for HSCT. Of 1114 patients, 71 (6.4%) received HSCT in CR1. Indications included high-risk cytogenetic abnormalities and non-CR on day 33. Patients with B-cell precursor (BCP) ALL and a prednisolone poor response (PPR) received HSCT when leukocyte antigen-matched siblings were available. The 4-year overall survival (OS) of transplanted patients was 78.8% (confidence interval 67.3-86.6). Multivariate analysis revealed that cord blood transplantation was associated with poor OS. For BCP-ALL patients with PPR who achieved CR1 after induction therapy, HSCT in CR1 showed excellent outcomes (4-year OS 90.9%) but demonstrated no survival advantage as the outcome with chemotherapy was also excellent (4-year OS 97.0%). This study suggests that in BCP-ALL patients PPR is not an indication for HSCT in CR1. Precise evaluation of treatment responses would increase sophistication of indications for HSCT in CR1.

Close interaction with bone marrow mesenchymal stromal cells induces the development of cancer stem cell-like immunophenotype in B cell precursor acute lymphoblastic leukemia cells.

Minimal residual disease of leukemia may reside in the bone marrow (BM) microenvironment and escape the effects of chemotherapeutic agents. This study investigated interactions between B cell precursor (BCP)-acute lymphoblastic leukemia (ALL) cells and BM mesenchymal stromal cells (BM-MSCs) in vitro. Five BCP-ALL cell lines established from pediatric patients and primary samples from a BCP-ALL patient were examined by flow cytometry and immunocytochemistry for expression of specific cell surface markers and cell adhesion proteins. The cell lines developed chemoresistance to commonly used anti-leukemic agents through adhesion to MSC-TERT cells in long-term culture. The change in chemosensitivity after adhering to BM-MSCs was associated with the expression of CD34, CD133, P-glycoprotein and BCRP/ABCG2, and downregulation of CD38. Similar phenotypic changes were observed in primary samples obtained by marrow aspiration or biopsy from a BCP-ALL patient. BM-MSC-adhering leukemia cells also showed deceleration of cell proliferation and expressed proteins in the Cadherin and Integrin pathways. These results suggest that BCP-ALL cells residing in the BM microenvironment may acquire chemoresistance by altering their phenotype to resemble that of cancer stem cells. Our results indicate that cell adhesion could be potentially targeted to improve the chemosensitivity of residual BCP-ALL cells in the BM microenvironment.

Magnetic resonance-guided focused ultrasound ablation of hypothalamic hamartoma as a disconnection surgery: a case report.

We report the case of a patient with hypothalamic hamartoma (HH) who was successfully treated with magnetic resonance-guided focused ultrasound (MRgFUS) for ablation as a disconnection surgery. A 26-year-old man with gelastic epilepsy had been diagnosed with HH at 3 years of age, and antiepileptic drugs were administered due to worsening episodes. Magnetic resonance imaging showed a sessile parahypothalamic hamartoma and MRgFUS ablation was performed, creating an oval-shaped lesion at the boundary area of the HH. Dramatic improvements in seizure symptoms were noted, and he was seizure-free on decreased antiepileptic drugs without any adverse events over the 1-year follow-up period.

Massively parallel variant characterization identifies NUDT15 alleles associated with thiopurine toxicity.

As a prototype of genomics-guided precision medicine, individualized thiopurine dosing based on pharmacogenetics is a highly effective way to mitigate hematopoietic toxicity of this class of drugs. Recently, NUDT15 deficiency was identified as a genetic cause of thiopurine toxicity, and NUDT15-informed preemptive dose reduction was quickly adopted in clinical settings. To exhaustively identify pharmacogenetic variants in this gene, we developed massively parallel NUDT15 function assays to determine the variants' effect on protein abundance and thiopurine cytotoxicity. Of the 3,097 possible missense variants, we characterized the abundance of 2,922 variants and found 54 hotspot residues at which variants resulted in complete loss of protein stability. Analyzing 2,935 variants in the thiopurine cytotoxicity-based assay, we identified 17 additional residues where variants altered NUDT15 activity without affecting protein stability. We identified structural elements key to NUDT15 stability and/or catalytical activity with single amino acid resolution. Functional effects for NUDT15 variants accurately predicted toxicity risk alleles in patients treated with thiopurines with far superior sensitivity and specificity compared to bioinformatic prediction algorithms. In conclusion, our massively parallel variant function assays identified 1,152 deleterious NUDT15 variants, providing a comprehensive reference of variant function and vastly improving the ability to implement pharmacogenetics-guided thiopurine treatment individualization.

Risk-adjusted therapy for pediatric non-T cell ALL improves outcomes for standard risk patients: results of JACLS ALL-02.

This study was a second multicenter trial on childhood ALL by the Japan Childhood Leukemia Study Group (JACLS) to improve outcomes in non-T ALL. Between April 2002 and March 2008, 1138 children with non-T ALL were enrolled in the JACLS ALL-02 trial. Patients were stratified into three groups using age, white blood cell count, unfavorable genetic abnormalities, and treatment response: standard risk (SR), high risk (HR), and extremely high risk (ER). Prophylactic cranial radiation therapy (PCRT) was abolished except for CNS leukemia. Four-year event-free survival (4yr-EFS) and 4-year overall survival (4yr-OS) rates for all patients were 85.4% ± 1.1% and 91.2% ± 0.9%, respectively. Risk-adjusted therapy resulted in 4yr-EFS rates of 90.4% ± 1.4% for SR, 84.9% ± 1.6% for HR, and 66.5% ± 4.0% for ER. Based on NCI risk classification, 4yr-EFS rates were 88.2% in NCI-SR and 76.4% in NCI-HR patients, respectively. Compared to previous trial ALL-97, 4yr-EFS of NCI-SR patients was significantly improved (88.2% vs 81.2%, log rank p = 0.0004). The 4-year cumulative incidence of isolated (0.9%) and total (1.5%) CNS relapse were significantly lower than those reported previously. In conclusion, improved EFS in NCI-SR patients and abolish of PCRT was achieved in ALL-02.

Discontinuation of L-asparaginase and poor response to prednisolone are associated with poor outcome of ETV6-RUNX1-positive pediatric B-cell precursor acute lymphoblastic leukemia.

ETV6-RUNX1-positive B precursor acute lymphoblastic leukemia (B-ALL) is a common subtype of pediatric B-ALL that has shown excellent outcomes in contemporary clinical trials for pediatric B-ALL. Examinations of the possibility of reducing therapeutic intensity may thus be explored. This prospective study examined outcomes in 205 pediatric patients with ETV6-RUNX1-positive B-ALL uniformly treated following the Japan Association of Childhood Leukemia Study Group (JACLS) ALL-02 protocol. The JACLS ALL-02 protocol does not employ minimal residual disease detected by polymerase chain reaction (PCR-MRD)-based risk stratification; however, 4-year event-free survival (EFS) and overall survival (OS) were 94.4 ± 1.6 and 97.5 ± 1.1%, respectively. In particular, 92 of 205 (44.9%) patients were successfully treated with a less intensive regimen involving only two cycles of high dose methotrexate and one course of re-induction therapy comprising vincristine, L-asparaginase (L-asp), pirarubicin, and prednisolone. Multivariate analysis revealed that discontinuation of L-asp and poor response to prednisolone was, respectively, associated with poor EFS (HR 6.3; 95% CI 1.3-27.0) and OS (HR 17.5; 95% CI 2.3-130), suggesting that the majority of ETV6-RUNX1-positive B-ALL cases may be cured by a less-intensive chemotherapy regimen if the risk stratification system including PCR-MRD monitoring and insufficient use of L-asp is avoided.

The genetic basis and cell of origin of mixed phenotype acute leukaemia.

Mixed phenotype acute leukaemia (MPAL) is a high-risk subtype of leukaemia with myeloid and lymphoid features, limited genetic characterization, and a lack of consensus regarding appropriate therapy. Here we show that the two principal subtypes of MPAL, T/myeloid (T/M) and B/myeloid (B/M), are genetically distinct. Rearrangement of ZNF384 is common in B/M MPAL, and biallelic WT1 alterations are common in T/M MPAL, which shares genomic features with early T-cell precursor acute lymphoblastic leukaemia. We show that the intratumoral immunophenotypic heterogeneity characteristic of MPAL is independent of somatic genetic variation, that founding lesions arise in primitive haematopoietic progenitors, and that individual phenotypic subpopulations can reconstitute the immunophenotypic diversity in vivo. These findings indicate that the cell of origin and founding lesions, rather than an accumulation of distinct genomic alterations, prime tumour cells for lineage promiscuity. Moreover, these findings position MPAL in the spectrum of immature leukaemias and provide a genetically informed framework for future clinical trials of potential treatments for MPAL.