NOTCH1 fusions in pediatric T-cell lymphoblastic lymphoma: A high-risk subgroup with CCL17 (TARC) levels as diagnostic biomarker.

Twenty percent of children with T-cell lymphoblastic lymphoma (T-LBL) will relapse and have an extremely poor outcome. Currently, we can identify a genetically low-risk subgroup in pediatric T-LBL, yet these high-risk patients who need intensified or alternative treatment options remain undetected. Therefore, there is an urgent need to recognize these high-risk T-LBL patients through identification of molecular characteristics and biomarkers. By using RNA sequencing which was performed in 29/49 T-LBL patients who were diagnosed in the Princess Maxima Center for Pediatric Oncology between 2018 and 2023, we discovered a previously unknown high-risk biological subgroup of children with T-LBL. This subgroup is characterized by NOTCH1 gene fusions, found in 21% of our T-LBL cohort (6/29). All patients presented with a large mediastinal mass, pleural/pericardial effusions, and absence of blasts in the bone marrow, blood, and central nervous system. Blood CCL17 (C-C Motif Chemokine Ligand 17, TARC) levels were measured at diagnosis in 26/29 patients, and all six patients with NOTCH1 gene fusions patients exclusively expressed highly elevated blood CCL17 levels, defining a novel and previously not known clinically relevant biomarker for T-cell lymphoblastic lymphoma. Four out of these six patients relapsed during therapy, a fifth developed a therapy-related acute myeloid leukemia during maintenance therapy. These data indicate that T-LBL patients with a NOTCH1 fusion have a high risk of relapse which can be easily identified using a blood CCL17 screening at diagnosis. Further molecular characterization through NOTCH1 gene fusion analysis offers these patients the opportunity for treatment intensification or new treatment strategies.

Biologic and clinical analysis of childhood gamma delta T-ALL identifies LMO2/STAG2 rearrangements as extremely high-risk.

Acute lymphoblastic leukemia expressing the gamma delta T cell receptor (yo T-ALL) is a poorly understood disease. We studied 200 children with yo T-ALL from 13 clinical study groups to understand the clinical and genetic features of this disease. We found age and genetic drivers were significantly associated with outcome. yo T-ALL diagnosed in children under three years of age was extremely high-risk and enriched for genetic alterations that result in both LMO2 activation and STAG2 inactivation. Mechanistically, using patient samples and isogenic cell lines, we show that inactivation of STAG2 profoundly perturbs chromatin organization by altering enhancer-promoter looping, resulting in deregulation of gene expression associated with T-cell differentiation. High throughput drug screening identified a vulnerability in DNA repair pathways arising from STAG2 inactivation, which can be targeted by Poly(ADP-ribose) polymerase (PARP) inhibition. These data provide a diagnostic framework for classification and risk stratification of pediatric yo T-ALL.

Bevacizumab Treatment for Patients with NF2-Related Schwannomatosis: A Single Center Experience.

(1) Background: NF2-related schwannomatosis, characterized by the development of bilateral vestibular schwannomas, often necessitates varied treatment approaches. Bevacizumab, though widely utilized, demonstrates variable effectiveness on hearing and tumor growth. At the same time, (serious) adverse events have been frequently reported. (2) Methods: A single center retrospective study was conducted, on NF2-related schwannomatosis patients treated with bevacizumab from 2013 to 2023, with the aim to assess treatment-related and clinical outcomes. Outcomes of interest comprised hearing, radiologic response, symptoms, and adverse events. (3) Results: Seventeen patients received 7.5 mg/kg bevacizumab for 7.1 months. Following treatment, 40% of the patients experienced hearing improvement, 53%, stable hearing, and 7%, hearing loss. Vestibular schwannoma regression occurred in 31%, and 69% remained stable. Further symptomatic improvement was reported by 41%, stable symptoms by 47%, and worsened symptoms by 12%. Treatment discontinuation due to adverse events was observed in 29% of cases. Hypertension (82%) and fatigue (29%) were most frequently reported, with no occurrences of grade 4/5 toxicities. (4) Conclusion: Supporting previous studies, bevacizumab demonstrated positive effects on hearing, tumor control, and symptoms in NF2-related schwannomatosis, albeit with common adverse events. Therefore, careful consideration of an appropriate management strategy is warranted.

Long-Term Outcomes in Patients With Spontaneous Cerebellar Hemorrhage: An International Cohort Study.

BACKGROUND: Spontaneous intracerebral hemorrhage (ICH) in the cerebellum has a poor short-term prognosis, whereas data on the long-term case fatality and recurrent vascular events are sparse. Herewith, we aimed to assess the long-term case fatality and recurrence rate of vascular events after a first cerebellar ICH. METHODS: In this international cohort study, we included patients from 10 hospitals (the United States and Europe from 1997 to 2017) aged ≥18 years with a first spontaneous cerebellar ICH who were discharged alive. Data on long-term case fatality and recurrence of vascular events (recurrent ICH [supratentoria or infratentorial], ischemic stroke, myocardial infarction, or major vascular surgery) were collected for survival analysis and absolute event rate calculation. RESULTS: We included 405 patients with cerebellar ICH (mean age [SD], 72 [13] years, 49% female). The median survival time was 67 months (interquartile range, 23-100 months), with a cumulative survival rate of 34% at 10-year follow-up (median follow-up time per center ranged: 15-80 months). In the 347 patients with data on vascular events 92 events occurred in 78 patients, after initial cerebellar ICH: 31 (8.9%) patients had a recurrent ICH (absolute event rate, 1.8 per 100 patient-years [95% CI, 1.2-2.6]), 39 (11%) had an ischemic stroke (absolute event rate, 2.3 [95% CI, 1.6-3.2]), 13 (3.7%) had a myocardial infarction (absolute event rate, 0.8 [95% CI, 0.4-1.3]), and 5 (1.4%) underwent major vascular surgery (absolute event rate, 0.3 [95% CI, 0.1-0.7]). The median time to a first vascular event during follow-up was 27 months (interquartile range, 8.7-50 months), with a cumulative hazard of 47% at 10 years. CONCLUSIONS: The long-term prognosis of patients who survive a first spontaneous cerebellar ICH is poor and comparable to that of patients who survive a first supratentorial ICH. Further identification of patients at high risk of vascular events following the initial cerebellar ICH is needed. Including patients with cerebellar ICH in randomized controlled trials on secondary prevention of patients with ICH is warranted.

The effects of percutaneous branch pulmonary artery interventions on exercise capacity, lung perfusion, and right ventricular function in biventricular CHD: a systematic review.

BACKGROUND: Branch pulmonary artery stenosis is common after surgical repair in patients with biventricular CHD and often requires reinterventions. However, (long-term) effects of percutaneous branch pulmonary artery interventions on exercise capacity, right ventricular function, and lung perfusion remain unclear. This review describes the (long-term) effects of percutaneous branch pulmonary artery interventions on exercise capacity, right ventricular function, and lung perfusion following PRISMA guidelines. METHODS: We performed a systematic search in PubMed, Embase, and Cochrane including studies about right ventricular function, exercise capacity, and lung perfusion after percutaneous branch pulmonary artery interventions. Study selection, data extraction, and quality assessment were performed by two researchers independently. RESULTS: In total, 7 eligible studies with low (n = 2) and moderate (n = 5) risk of bias with in total 330 patients reported on right ventricular function (n = 1), exercise capacity (n = 2), and lung perfusion (n = 7). Exercise capacity and lung perfusion seem to improve after a percutaneous intervention for branch pulmonary artery stenosis. No conclusions about right ventricular function or remodelling, differences between balloon and stent angioplasty or specific CHD populations could be made. CONCLUSION: Although pulmonary artery interventions are frequently performed in biventricular CHD, data on relevant outcome parameters such as exercise capacity, lung perfusion, and right ventricular function are largely lacking. An increase in exercise capacity and improvement of lung perfusion to the affected lung has been described in case of mild to more severe pulmonary artery stenosis during relatively short follow-up. However, there is need for future studies to evaluate the effect of pulmonary artery interventions in various CHD populations.

Biologic and clinical features of childhood gamma delta T-ALL: identification of STAG2/LMO2 γδ T-ALL as an extremely high risk leukemia in the very young.

PURPOSE: Gamma delta T-cell receptor-positive acute lymphoblastic leukemia (γδ T-ALL) is a high-risk but poorly characterized disease. METHODS: We studied clinical features of 200 pediatric γδ T-ALL, and compared the prognosis of 93 cases to 1,067 protocol-matched non-γδ T-ALL. Genomic features were defined by transcriptome and genome sequencing. Experimental modeling was used to examine the mechanistic impacts of genomic alterations. Therapeutic vulnerabilities were identified by high throughput drug screening of cell lines and xenografts. RESULTS: γδ T-ALL in children under three was extremely high-risk with 5-year event-free survival (33% v. 70% [age 3-<10] and 73% [age ≥10], P =9.5 x 10 -5 ) and 5-year overall survival (49% v. 78% [age 3-<10] and 81% [age ≥10], P =0.002), differences not observed in non-γδ T-ALL. γδ T-ALL in this age group was enriched for genomic alterations activating LMO2 activation and inactivating STAG2 inactivation ( STAG2/LMO2 ). Mechanistically, we show that inactivation of STAG2 profoundly perturbs chromatin organization by altering enhancer-promoter looping resulting in deregulation of gene expression associated with T-cell differentiation. Drug screening showed resistance to prednisolone, consistent with clinical slow treatment response, but identified a vulnerability in DNA repair pathways arising from STAG2 inactivation, which was efficaciously targeted by Poly(ADP-ribose) polymerase (PARP) inhibition, with synergism with HDAC inhibitors. Ex-vivo drug screening on PDX cells validated the efficacy of PARP inhibitors as well as other potential targets including nelarabine. CONCLUSION: γδ T-ALL in children under the age of three is extremely high-risk and enriched for STAG2/LMO2 ALL. STAG2 loss perturbs chromatin conformation and differentiation, and STAG2/LMO2 ALL is sensitive to PARP inhibition. These data provide a diagnostic and therapeutic framework for pediatric γδ T-ALL. SUPPORT: The authors are supported by the American and Lebanese Syrian Associated Charities of St Jude Children's Research Hospital, NCI grants R35 CA197695, P50 CA021765 (C.G.M.), the Henry Schueler 41&9 Foundation (C.G.M.), and a St. Baldrick's Foundation Robert J. Arceci Innovation Award (C.G.M.), Gabriella Miller Kids First X01HD100702 (D.T.T and C.G.M.) and R03CA256550 (D.T.T. and C.G.M.), F32 5F32CA254140 (L.M.), and a Garwood Postdoctoral Fellowship of the Hematological Malignancies Program of the St Jude Children's Research Hospital Comprehensive Cancer Center (S.K.). This project was supported by the National Cancer Institute of the National Institutes of Health under the following award numbers: U10CA180820, UG1CA189859, U24CA114766, U10CA180899, U10CA180866 and U24CA196173. DISCLAIMER: The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The funding agencies were not directly involved in the design of the study, gathering, analysis and interpretation of the data, writing of the manuscript, or decision to submit the manuscript for publication.

"To feel supported in your community is to feel loved": Cultivating community and support for Black transmasculine people navigating anti-Black racism, transphobia, and COVID-19 pandemic.

Background: Black transmasculine people are disproportionately affected by a myriad of intersecting stressors including racism (specifically anti-Black racism), sexism, and cissexism. Black transmasculine people are exposed daily to systemic oppression such as transphobia, dehumanization, and violence, making this community more vulnerable to mental health and physical health concerns. These experiences are further compounded by the lack of relevant research about the unique experiences of Black transmasculine people during the COVID-19 pandemic. Aims: Utilizing a critical intersectionality lens and Prilleltensky's psychopolitical validity as guiding frameworks, the present study investigates the need for support and community for Black transmasculine people when navigating anti-Black racism and transphobia during the COVID-19 pandemic. Methods: The researchers integrated intersectionality and Prilleltensky's psychopolitical validity as frameworks paired with the constructivist grounded theory paradigm outlined by Charmaz to analyze data. The researchers co-constructed meaning from participants' (N = 32) perspectives to provide a theoretical understanding of how Black transmasculine participants' perceived community and support during COVID-19 pandemic. Results: The researchers developed a model of pathways toward community and support. The model suggests two levels: (a) locating awareness of community and support, and (b) integrated action toward community and support. The approaches are integrated from within group actions that can be facilitated from outside the community on micro and macro sociological levels to provide holistic support and community for Black transmasculine people. Discussion: This model extends the current literature on liberation and community psychology regarding the different levels of support for Black transmasculine people. This intervention can provide awareness and insight about working alongside the Black transmasculine community to address their unique needs of support and community. These findings hope to enhance clinical practices and identify strategies to promote wellness among Black transmasculine people.

Indicators of Neighborhood-Level Socioeconomic Position and Pediatric Critical Illness.

BACKGROUND: With recent prioritization of equity in pediatric health outcomes, a shift to examine neighborhood-level health care disparities within pediatric populations has occurred, specifically in the context of critical illness. RESEARCH QUESTION: Does an association exist between individual indicators of neighborhood-level disadvantage and incidence of PICU admission? STUDY DESIGN AND METHODS: Pediatric patients younger than 18 years admitted to a PICU in a large urban tertiary pediatric hospital from January 1, 2016, through December 31, 2019, with a residential address in the city of Baltimore or Baltimore County on the day of admission were included in this ecological study. Demographic and clinical characteristics of children admitted to the PICU were summarized, with the primary outcome being PICU admission. Unadjusted negative binomial regression was used to examine the association between census tract-level PICU admissions and the previously described census tract-level indicators of neighborhood socioeconomic position. Regression models included an offset term for the population younger than 18 years for each census tract; results of models are reported as incidence rate ratios (IRRs) with corresponding 95% CIs. RESULTS: We identified 2,476 PICU admissions: 1,351 patients from the city of Baltimore (10.25 per 1,000 children) and 1,125 patients from Baltimore County (6.31 per 1,000 children). Most PICU admissions (n = 906 [68%]) for the city of Baltimore represented an area deprivation index (ADI) of > 60, whereas most Baltimore County PICU admissions (n = 919 [82.3%]) represented an ADI of < 60. At the neighborhood level, the percentage of families living below the poverty line was associated with greater incidence of PICU admission in the city of Baltimore (IRR, 1.09; 95% CI, 1.00-1.18) and Baltimore County (IRR, 1.19; 95% CI, 1.05-1.36). For every $10,000 increase in median household income, PICU admission rates dropped by 9% for the city of Baltimore (IRR, 0.91; 95% CI, 0.86-0.95) and Baltimore County (IRR, 0.91; 95% CI, 0.88-0.94). Neighborhoods with vacant housing units also were associated with a higher incidence of PICU admission in the city of Baltimore (IRR, 1.10; 95% CI, 1.01-1.21) and Baltimore County (IRR, 1.46; 95% CI, 1.21-1.77), as was a 10% increase in occupied homes without vehicles (city of Baltimore: IRR, 1.14; 95% CI, 1.07-1.21; Baltimore County: IRR, 1.23; 95% CI, 1.11-1.37). INTERPRETATION: Health outcomes of pediatric critical illness should be examined in the context of structural determinants of health, including neighborhood-level and environmental characteristics.

Elevated enhancer-oncogene contacts and higher oncogene expression levels by recurrent CTCF inactivating mutations in acute T cell leukemia.

Monoallelic inactivation of CCCTC-binding factor (CTCF) in human cancer drives altered methylated genomic states, altered CTCF occupancy at promoter and enhancer regions, and deregulated global gene expression. In patients with T cell acute lymphoblastic leukemia (T-ALL), we find that acquired monoallelic CTCF-inactivating events drive subtle and local genomic effects in nearly half of t(5; 14) (q35; q32.2) rearranged patients, especially when CTCF-binding sites are preserved in between the BCL11B enhancer and the TLX3 oncogene. These solitary intervening sites insulate TLX3 from the enhancer by inducing competitive looping to multiple binding sites near the TLX3 promoter. Reduced CTCF levels or deletion of the intervening CTCF site abrogates enhancer insulation by weakening competitive looping while favoring TLX3 promoter to BCL11B enhancer looping, which elevates oncogene expression levels and leukemia burden.

Proton Radiotherapy for Vestibular Schwannomas in Patients with NF2-Related Schwannomatosis: A Case Series.

(1) Background: This study aimed to evaluate the efficacy and treatment-related toxicity of proton radiotherapy (PRT) for vestibular schwannoma (VS) in patients with neurofibromatosis type 2-related schwannomatosis (NF2). (2) Methods: Consecutive NF2 patients treated with PRT for VS between 2004 and 2016 were retrospectively evaluated, focusing on tumor volume, facial and trigeminal nerve function, hearing, tinnitus, vestibular symptoms, and the need for salvage therapy after PRT. (3) Results: Eight patients were included (median age 36 years, 50% female). Median follow-up was 71 months. Five (63%) patients received fractionated PRT and three (38%) received PRT radiosurgery for VS. Six patients (75%) received prior VS surgery; three also received bevacizumab. Six patients (75%) did not require salvage therapy after PRT. Two patients (25%) with residual hearing lost it after PRT, and six had already lost ipsilateral hearing prior to PRT. Tumor and treatment-related morbidity could be evaluated in six patients. Following PRT, conditions that occurred or worsened were: facial paresis in five (83%), trigeminal hypoesthesia in two (33%), tinnitus in two (33%), and vestibular symptoms in four patients (67%). (4) Conclusion: After PRT for VS, the majority of the NF2 patients in the cohort did not require additional therapy. Tumor and/or treatment-related cranial nerve deficits were common. This is at least partly explained by the use of PRT as a salvage treatment after surgery or bevacizumab, in the majority of cases. There remains the further opportunity to elucidate the efficacy and toxicity of proton radiotherapy as a primary treatment.

STAT5 does not drive steroid resistance in T-cell acute lymphoblastic leukemia despite the activation of BCL2 and BCLXL following glucocorticoid treatment.

Physiological and pathogenic interleukin-7-receptor (IL7R)-induced signaling provokes glucocorticoid resistance in a subset of patients with pediatric T-cell acute lymphoblastic leukemia (T-ALL). Activation of downstream STAT5 has been suggested to cause steroid resistance through upregulation of anti-apoptotic BCL2, one of its downstream target genes. Here we demonstrate that isolated STAT5 signaling in various T-ALL cell models is insufficient to raise cellular steroid resistance despite upregulation of BCL2 and BCL-XL. Upregulation of anti-apoptotic BCL2 and BCLXL in STAT5-activated T-ALL cells requires steroid-induced activation of NR3C1. For the BCLXL locus, this is facilitated by a concerted action of NR3C1 and activated STAT5 molecules at two STAT5 regulatory sites, whereas for the BCL2 locus this is facilitated by binding of NR3C1 at a STAT5 binding motif. In contrast, STAT5 occupancy at glucocorticoid response elements does not affect the expression of NR3C1 target genes. Strong upregulation of BIM, a NR3C1 pro-apoptotic target gene, upon prednisolone treatment can counterbalance NR3C1/STAT5-induced BCL2 and BCL-XL expression downstream of IL7- induced or pathogenic IL7R signaling. This explains why isolated STAT5 activation does not directly impair the steroid response. Our study suggests that STAT5 activation only contributes to steroid resistance in combination with cellular defects or alternative signaling routes that disable the pro-apoptotic and steroid-induced BIM response.

Reversal of IKZF1-induced glucocorticoid resistance by dual targeting of AKT and ERK signaling pathways.

Although long-term survival in pediatric acute lymphoblastic leukemia (ALL) currently exceeds 90%, some subgroups, defined by specific genomic aberrations, respond poorly to treatment. We previously reported that leukemias harboring deletions or mutations affecting the B-cell transcription factor IKZF1 exhibit a tumor cell intrinsic resistance to glucocorticoids (GCs), one of the cornerstone drugs used in the treatment of ALL. Here, we identified increased activation of both AKT and ERK signaling pathways as drivers of GC resistance in IKZF1-deficient leukemic cells. Indeed, combined pharmacological inhibition of AKT and ERK signaling effectively reversed GC resistance in IKZF1-deficient leukemias. As inhibitors for both pathways are under clinical investigation, their combined use may enhance the efficacy of prednisolone-based therapy in this high-risk patient group.

Pediatric Precursor B-Cell Lymphoblastic Malignancies: From Extramedullary to Medullary Involvement.

B-cell lymphoblastic lymphoma (BCP-LBL) and B-cell acute lymphoblastic leukemia (BCP-ALL) are the malignant counterparts of immature B-cells. BCP-ALL is the most common hematological malignancy in childhood, while BCP-LBL accounts for only 1% of all hematological malignancies in children. Therefore, BCP-ALL has been well studied and treatment protocols have changed over the last decades, whereas treatment for BCP-LBL has stayed roughly the same. Clinical characteristics of 364 pediatric patients with precursor B-cell malignancies were studied, consisting of BCP-LBL (n = 210) and BCP-ALL (n = 154) patients. Our results indicate that based on the clinical presentation of disease, B-cell malignancies probably represent a spectrum ranging from complete isolated medullary disease to apparent complete extramedullary disease. Hepatosplenomegaly and peripheral blood involvement are the most important discriminators, as both seen in 80% and 95% of the BCP-ALL patients and in 2% of the BCP-LBL patients, respectively. In addition, we show that the overall survival rates in this cohort differ significantly between BCP-LBL and BCP-ALL patients aged 1−18 years (p = 0.0080), and that the outcome for infants (0−1 years) with BCP-LBL is significantly decreased compared to BCP-LBL patients of all other pediatric ages (p < 0.0001).

JAK3 mutations and mitochondrial apoptosis resistance in T-cell acute lymphoblastic leukemia.

Resistance to mitochondrial apoptosis predicts inferior treatment outcomes in patients with diverse tumor types, including T-cell acute lymphoblastic leukemia (T-ALL). However, the genetic basis for variability in this mitochondrial apoptotic phenotype is poorly understood, preventing its rational therapeutic targeting. Using BH3 profiling and exon sequencing analysis of childhood T-ALL clinical specimens, we found that mitochondrial apoptosis resistance was most strongly associated with activating mutations of JAK3. Mutant JAK3 directly repressed apoptosis in leukemia cells, because its inhibition with mechanistically distinct pharmacologic inhibitors resulted in reversal of mitochondrial apoptotic blockade. Inhibition of JAK3 led to loss of MEK, ERK and BCL2 phosphorylation, and BH3 profiling revealed that JAK3-mutant primary T-ALL patient samples were characterized by a dependence on BCL2. Treatment of JAK3-mutant T-ALL cells with the JAK3 inhibitor tofacitinib in combination with a spectrum of conventional chemotherapeutics revealed synergy with glucocorticoids, in vitro and in vivo. These findings thus provide key insights into the molecular genetics of mitochondrial apoptosis resistance in childhood T-ALL, and a compelling rationale for a clinical trial of JAK3 inhibitors in combination with glucocorticoids for patients with JAK3-mutant T-ALL.

Impact of gender-affirming care bans on transgender and gender diverse youth: Parental figures' perspective.

Transgender and gender diverse (TGD) youth in the United States are met with systemic barriers that affect their physical and mental health. Recent scholarship has found that TGD youth have been negatively impacted as a result of antitransgender federal, state, and local laws and bills. Given the crucial role of parental figures in the well-being of TGD youth (e.g., supporting their child's health-care decisions), parents can provide important insight about the experiences of their children as they navigate the effects of antitransgender legislation. This study aimed to explore parental figures' perceptions of how bans on gender affirming care affect their TGD child and parental figures' advice for legislators/policymakers regarding the impact of these laws and bills on the well-being of TGD youth. Responses to an online survey with 134 self-identified parental figures of TGD youth were analyzed. Thematic analysis revealed five themes regarding the impact that these antitransgender laws and bills have on TGD youth, including (a) depression and suicidal ideation/risk of suicide, (b) anxiety, (c) increased gender dysphoria, (d) decreased safety and increased stigma, and (e) lack of access to medical care. Parental figures also provided direct feedback to legislators/policymakers regarding the impact of these laws and bills on the well-being of TGD youth, including (a) transgender youth health is not a political issue, (b) decriminalize gender affirming medical care, (c) decrease discrimination and violence against transgender people, and (d) become educated on transgender health-care issues. Recommendations for research and practice are discussed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Phosphoproteomic profiling of T cell acute lymphoblastic leukemia reveals targetable kinases and combination treatment strategies.

Protein kinase inhibitors are amongst the most successful cancer treatments, but targetable kinases activated by genomic abnormalities are rare in T cell acute lymphoblastic leukemia. Nevertheless, kinases can be activated in the absence of genetic defects. Thus, phosphoproteomics can provide information on pathway activation and signaling networks that offer opportunities for targeted therapy. Here, we describe a mass spectrometry-based global phosphoproteomic profiling of 11 T cell acute lymphoblastic leukemia cell lines to identify targetable kinases. We report a comprehensive dataset consisting of 21,000 phosphosites on 4,896 phosphoproteins, including 217 kinases. We identify active Src-family kinases signaling as well as active cyclin-dependent kinases. We validate putative targets for therapy ex vivo and identify potential combination treatments, such as the inhibition of the INSR/IGF-1R axis to increase the sensitivity to dasatinib treatment. Ex vivo validation of selected drug combinations using patient-derived xenografts provides a proof-of-concept for phosphoproteomics-guided design of personalized treatments.

High Prevalence of Constitutional Mismatch Repair Deficiency in a Pediatric T-cell Lymphoblastic Lymphoma Cohort.

This study describes the clinical characteristics of a complete Dutch T-cell lymphoblastic lymphoma (T-LBL) cohort, including second primary malignancies and comorbidities. We show that over 10% of patients in this complete T-LBL cohort have been diagnosed with a cancer predisposition syndrome (CPS), consisting almost exclusively of constitutional mismatch repair deficiency (CMMRD). The clinical characteristics of sporadic T-LBL patients were compared with T-LBL patients that have been diagnosed with CMMRD. This shows that disease presentation is comparable but that disease localization in CMMRD patients might be more localized. The percentage of CPS seems reliable considering the completeness of the cohort of Dutch T-LBL patients and might even be an underestimation (possibility of undiagnosed CPS patients in cohort). As the frequency of an underlying predisposition syndrome among T-LBL patients may be underestimated at present, we advocate for screening all pediatric T-LBL patients for the presence of germline mutations in mismatch repair genes.