Judicious use of precise fluorescence in situ hybridisation panels guided by population prevalence may assist pragmatic detection of clinically targetable Philadelphia chromosome-like acute lymphoblastic leukaemia fusions: a systematic review.

Diagnosis of Philadelphia chromosome-like acute lymphoblastic leukaemia (Ph-like ALL) in the real-world remains challenging because of definitional complexities, the diverse diagnostic techniques available and the cost, expertise and time involved. We summarise evidence for diagnosis of clinically important Ph-like ALL related genomic lesions using fluorescence in situ hybridisation (FISH) targeting only clinically important and actionable lesions, an accessible and cost-effective diagnostic technique. Electronic databases were interrogated using broad MeSH terms for articles reporting a detailed FISH strategy for diagnosis of Ph-like ALL published since 2014, yielding 653 full text articles and abstracts. We searched the National Library of Medicine Databases including PubMed, Medline, Embase, Cochrane and relevant abstracts. We included studies with a primary aim of determining the utility of FISH for Ph-like ALL diagnosis and studies with broader aims demonstrating Ph-like ALL diagnostic algorithms which partially involved FISH. Nineteen studies met inclusion criteria. Evidence for FISH to detect CRLF2 rearrangements in Ph-like ALL is strongly established and evidence for FISH to detect non-CRLF2 lesions is evolving rapidly. We documented 1620 cases of non-CRLF2 Ph-like lesions diagnosed by FISH. Confirmatory side-by-side methods were applied in six studies (246 samples), four of which demonstrated 100% concordance of FISH results with alternative methods, while two studies demonstrated over 70% sensitivity and specificity. Additional studies demonstrated wide utilisation of FISH in Ph-like ALL classification across diverse geographies and ethnicities, with contrasting prevalence, implicating a need for targeted FISH strategies. In real-world cohorts, it may be clinically useful to prioritise limited early FISH in B-cell ALL (B-ALL) diagnostic algorithms to identify Ph-like abnormalities that respond to locally available kinase inhibitors to promote and prioritise broad access to effective targeted treatment. Additional studies are required to provide adequately powered validations and verifications of targeted Ph-like FISH panels to confirm sensitivity and specificity against side-by-side gold standard methods, and to define optimal local approaches.

CD146 Molecule Expression in B Cells Acute Lymphoblastic Leukemia (B-ALLs): A Flow-Cytometric Marker for an Accurate Diagnostic Workup.

Background: B-lineage acute lymphoblastic leukemias (B-ALL) harboring the t(9;22)(q34;q11)/BCR::ABL1 rearrangement represent a category with previously dismal prognosis whose management and outcome dramatically changed thanks to the use of tyrosine kinase inhibitors (TKIs) usage and more recently full chemo-free approaches. The prompt identification of these cases represents an important clinical need. Objectives: We sought to identify an optimized cytofluorimetric diagnostic panel to predict the presence of Philadelphia chromosome (Ph) in B-ALL cases by the introduction of CD146 in our multiparametric flow cytometry (MFC) panels. Methods: We prospectively evaluated a total of 245 cases of newly diagnosed B-ALLs with a CD146 positivity threshold >10% referred to the Division of Hematology of 'Sapienza' University of Rome. We compared the results of CD146 expression percentage and its mean fluorescence intensity (MFI) between Ph+ ALLs, Ph-like ALLs, and molecularly negative ALLs. Results: Seventy-nine of the 245 B-ALL cases (32%) did not present mutations at molecular testing, with 144/245 (59%) resulting in Ph+ ALL and 19/245 (8%) Ph-like ALLs. Comparing the 3 groups, we found that Ph+ B-ALLs were characterized by higher expression percentage of myeloid markers such as CD13, CD33, and CD66c and low expression of CD38; Ph+ B-ALL showed a higher CD146 expression percentage and MFI when compared with both molecular negative B-ALL and Ph-like ALLs; neither the mean percentage of CD146 expression neither CD146 MFI were statically different between molecular negative B-ALL and Ph-like ALLs. Conclusions: Our data demonstrate the association between CD146 expression and Ph+ ALLs. CD146, along with myeloid markers, may help to identify a distinctive immunophenotypic pattern, useful for rapid identification in the diagnostic routine of this subtype of B-ALLs that benefits from a specific therapeutic approach.

SOHO State of the Art Updates and Next Questions | Approach to BCR::ABL1-Like Acute Lymphoblastic Leukemia.

Philadelphia-like (Ph-like) or BCR::ABL1-like acute lymphoblastic leukemia (ALL) is a common high-risk subtype of B-cell precursor ALL (B-ALL) characterized by a diverse range of genetic alterations that challenge diagnose and converge on distinct kinase and cytokine receptor-activated gene expression profiles, resembling those from BCR::ABL1-positive ALL from which its nomenclature. The presence of kinase-activating genetic drivers has prompted the investigation in preclinical models and clinical settings of the efficacy of tyrosine kinase inhibitor (TKI)-based treatments. This was further supported by an inadequate response to conventional chemotherapy, high rates of induction failure and persistent measurable residual disease (MRD) positivity, which translate in lower survival rates compared to other B-ALL subtypes. Therefore, innovative approaches are underway, including the integration of TKIs with frontline regimens and the early introduction of immunotherapy strategies (monoclonal antibodies, T-cell engagers, drug-conjugates, and CAR-T cells). Allogeneic hematopoietic cell transplantation (HSCT) is currently recommended for adult BCR::ABL1-like ALL patients in first complete remission. However, the incorporation of novel therapies, a more accurate diagnosis and a more sensitive MRD assessment may modify the risk stratification and the indication for transplant in these patients.

[Efficacy and safety of chimeric antigen receptor T-cell therapy followed by allogeneic hematopoietic stem cell transplantation in 21 patients with Ph-like acute lymphoblastic leukemia].

Objective: To evaluate the efficacy and safety of chimeric antigen receptor T-cell (CAR-T) therapy followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with Ph-like acute lymphoblastic leukemia (Ph-ALL) . Methods: Patients with Ph-ALL who underwent CAR-T therapy followed by allo-HSCT from March 2018 to August 2023 at the First Affiliated Hospital of Soochow University were included, and their clinical data were retrospectively analyzed. Results: Of the 21 patients, 14 were male and 7 were female. The median age at the time of CAR-T therapy was 22 (6-50) years. Seven patients had ABL1-like rearrangements, and 14 had JAK-STAT rearrangements. Prior to CAR-T therapy, 12 patients experienced hematologic relapse; 7 were multiparameter flow cytometry minimal residual disease (MFC-MRD) -positive and 2 were MFC-MRD-negative. CAR-T cells were derived from patients' autologous lymphocytes. Nine patients were treated with CD19 CAR-T cells, and 12 were treated with CD19/CD22 CAR-T cells. After assessment on day 28 after CAR-T therapy, 95.2% of the patients achieved complete remission, with an MRD-negative remission rate of 75%. Nineteen patients developed grade 0-2 cytokine release syndrome (CRS) and 2 patients suffered grade 3 CRS, all cases of which resolved after treatment. All patients underwent allo-HSCT after CAR-T therapy. The median time from CAR-T therapy to allo-HSCT was 63 (38-114) days. Five patients experienced relapse after CAR-T therapy, including four with hematologic relapse and one with molecular relapse. The 3-year overall survival (OS) rates in the ABL1 and JAK-STAT groups were (83.3±15.2) % and (66.6±17.2) %, respectively (P=0.68) . The 3-year relapse-free survival (RFS) rates were (50.0±20.4) % and (55.6±15.4) % in the ABL1 and JAK-STAT groups, respectively. There was no significant difference in 3-year OS or RFS between the two groups. Conclusions: CAR-T therapy followed by allo-HSCT leads to rapid remission in most patients with Ph-ALL and prolongs leukemia-free survival.

The novel TERF2::PDGFRB fusion gene enhances tumorigenesis via PDGFRB/STAT5 signalling pathways and sensitivity to TKI in ph-like ALL.

Patients with Philadelphia chromosome-like acute lymphoblastic leukaemia (Ph-like ALL) often face a grim prognosis, with PDGFRB gene fusions being commonly detected in this subgroup. Our study has unveiled a newfound fusion gene, TERF2::PDGFRB, and we have found that patients carrying this fusion gene exhibit sensitivity to dasatinib. Ba/F3 cells harbouring the TERF2::PDGFRB fusion display IL-3-independent cell proliferation through activation of the p-PDGFRB and p-STAT5 signalling pathways. These cells exhibit reduced apoptosis and demonstrate sensitivity to imatinib in vitro. When transfused into mice, Ba/F3 cells with the TERF2::PDGFRB fusion gene induce tumorigenesis and a shortened lifespan in cell-derived graft models, but this outcome can be improved with imatinib treatment. In summary, we have identified the novel TERF2::PDGFRB fusion gene, which exhibits oncogenic potential both in vitro and in vivo, making it a potential therapeutic target for tyrosine kinase inhibitors (TKIs).

Comprehensive detection of CRLF2 alterations in acute lymphoblastic leukemia: a rapid and accurate novel approach.

Introduction: Acute lymphoblastic leukemia (ALL) is a prevalent childhood cancer with high cure rate, but poses a significant medical challenge in adults and relapsed patients. Philadelphia-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk subtype, with approximately half of cases characterized by CRLF2 overexpression and frequent concomitant IKZF1 deletions. Methods: To address the need for efficient, rapid, and cost-effective detection of CRLF2 alterations, we developed a novel RT-qPCR technique combining SYBR Green and highresolution melting analysis on a single plate. Results: The method successfully identified CRLF2 expression, P2RY8::CRLF2 fusions, and CRLF2 and JAK2 variants, achieving a 100% sensitivity and specificity. Application of this method across 61 samples revealed that 24.59% exhibited CRLF2 overexpression, predominantly driven by IGH::CRLF2 (73.33%). High Resolution Melting analysis unveiled concurrent CRLF2 or JAK2 variants in 8.19% of samples, as well as a dynamic nature of CRLF2 alterations during disease progression. Discussion: Overall, this approach provides an accurate identification of CRLF2 alterations, enabling improved diagnostic and facilitating therapeutic decision-making.

Philadelphia Chromosome Positive and Philadelphia-Like Acute Lymphoblastic Leukemia in Children and Adolescents: Current Management, Controversies and Emerging Concepts.

Philadelphia chromosome positive (Ph+) acute lymphoblastic lymphoma (ALL) is an uncommon subtype of ALL in children, seen in 2-5% cases. Diagnostic evaluation includes conventional karyotyping and detection of BCR-ABL1 translocation by fluorescence in-situ hybridization (FISH) or reverse transcriptase polymerase chain reaction (RT-PCR). For children, the frontline management includes combination of intensive chemotherapy along with imatinib (300-340 mg/m2/d) or dasatinib (60-80 mg/m2/d). Imatinib/dasatinib should be introduced in induction as soon as results for BCR-ABL are available. Minimal residual disease (MRD) monitoring is essential; multi-parametric flowcytometry and immunoglobulin/T-cell receptor rearrangement PCR are the preferred methods. Intrathecal therapy with at least 12 doses of methotrexate is adequate for central nervous system (CNS) prophylaxis, but cranial radiation is necessary for CNS3 involvement. Allogeneic hematopoietic stem cell transplantation (HSCT) in first remission may be considered in high-risk cases (persistent MRD positivity/induction failure). Maintenance therapy with tyrosine kinase inhibitors (TKI) in children is debatable, with potential concerns for long term adverse effects. At relapse, the choice of TKI is guided by the presence of BCR-ABL tyrosine kinase domain resistance mutations, although the frequency of resistance mutations in children are lower. Allogeneic HSCT is essential for consolidation in second remission, if not done. Ph-like ALL is a newly recognized molecular entity, with gene expression profile similar to Ph+ALL and poor survival outcomes. In resource-constrained settings, a stepwise cost-effective diagnostic evaluation should be considered among high-risk patients without recurrent genetic abnormalities. Current treatment strategies remain similar to Ph-negative ALL. Enrolment in clinical trials is encouraged for such children to evaluate potential targeted agents in this subtype.

A surrogate molecular approach for the detection of Philadelphia chromosome-like B-acute lymphoblastic leukemia.

BACKGROUND: Philadelphia chromosome (Ph)-like B-acute lymphoblastic leukemia (B-ALL) is a clinically significant, high-risk genetic subtype of B-ALL cases. There are few data on the incidence, characterization, and treatment outcomes of Ph-like ALL cases from low- and middle-income countries. There is a pressing need to establish a well-organized/cost-effective approach for identifying Ph-like ALL instances. METHODS: Multiplex reverse transcriptase polymerase chain reaction, nCounter NanoString, and fluorescence in situ hybridization were used to detect and characterize Ph-like ALL cases among recurrent genetic abnormalities (RGA)neg B-ALL cases. At the end of induction therapy, flow cytometry-minimal residual disease (MRD) assay was used to quantify MRD positivity in Ph-like ALL cases. RESULTS: Of 130 newly diagnosed B-ALL cases, 25% (BCR::ABL1), 4% (ETV6::RUNX1), 5% (TCF3::PBX1), 2% (KM2TA::AFF1), and 65% RGAneg B-ALL cases were revealed by multiplex reverse transcriptase polymerase chain reaction. Among RGAneg B-ALL cases, 24% Ph-like ALL cases using nCounter NanoString were identified, with 48% CRLF2high cases with 45% CRLF2::P2RY8 and 18% CRLF2::IGH rearrangements(∼r) revealed by fluorescence in situ hybridization. In 52% of CRLF2low cases, 17% ABL1 and JAK2∼r 8% EPOR::IGH & PDGRFB∼r were identified. Ph-like ALL cases had higher total leukocyte count (p < .05), male preponderance (p < .05), and high MRD-positivity/induction failure compared with RGAneg B-ALL cases. Furthermore, in Ph-like ALL cases, 11 significant genes using quantitative polymerase chain reaction were identified and validated. CRLF2, IGJ, CEACAM6, MUC4, SPATS2L and NRXN3 genes were overexpressed and show statistical significance (p < .05) in Ph-like ALL cases. CONCLUSIONS: This study showed the high incidence of Ph-like ALL cases with kinase activating alterations and treatment outcomes from low- and middle-income region. Furthermore, a surrogate cost-effective multiplex panel of 11 overexpressed genes for the prompt detection of Ph-like ALL cases is proposed. PLAIN LANGUAGE SUMMARY: Identification of recurrent gene abnormalities (RGA)neg B-acute lymphoblastic leukemia (B-ALL) cases using multiplex-reverse transcriptase polymerase chain reaction. Identification and characterization of Philadelphia (Ph)-like ALL cases using nCounter NanoString gene expression profiling and fluorescence in situ hybridization. Furthermore, Ph-like ALL cases were characterized according to CRLF2 expression and kinase-activating genomic alterations. Minimal residual disease of Ph-like ALL cases were quantified using flow cytometry-minimal residual disease assay. A surrogate molecular approach was established to detect Ph-like ALL cases from low- and middle-income countries.

Poor outcome of pediatric B-cell acute lymphoblastic leukemia associated with high level of CRLF2 gene expression in distinct molecular subtypes.

Background: Overexpression of the cytokine receptor-like factor 2 (CRLF2) gene is the most common feature in the Philadelphia chromosome (Ph)-like subtype of B-cell acute lymphoblastic leukemia (B-ALL). However, the predictive value of CRLF2 overexpression for the prognosis of pediatric B-ALL patients remain controversial. The molecular mechanisms that upregulate CRLF2 expression level in patients has not been fully elucidated. Methods: In this study, the prognostic impact of CRLF2 expression level on molecular types of B-ALL in pediatric patients from Zhujiang Hospital (n = 111) was retrospectively analyzed. Youden index analysis was used to categorize CRLF2 expression into 3 groups, and these categories more precisely described the differences in the prognosis of patients with varying expression levels of CRLF2 in both the Zhujiang Hospital cohort and the TARGET cohort. Results: We used the Zhujiang Hospital cohort as a discovery cohort to determine the cutoff value of CRLF2 expression. CRLF2-high patients accounted for approximately 6%. In addition, the percentage of bone marrow blast cells and initial white blood cell count in CRLF2-high patients were higher than those in CRLF2-low patients, and MRD turned negative slower. The results were validated in the TARGET cohort and indicated that CRLF2 overexpression could be subdivided by CRLF2 expression levels into 2 categories: CRLF2-high with a poor survival and CRLF2-medium with a good OS and EFS. Such heterogeneity was attributed to the different molecular mechanisms leading to CLRF2 upregulation, where the CRLF2 overexpression level was high in Ph-like B-ALL and medium in high hyperdiploid B-ALL. Conclusion: This study highlights the importance of the molecular mechanisms of the upregulation of CRLF2 expression in predicting the prognosis of pediatric B-ALL patients.

Neurofibromatosis Symptom-Lacking B-Cell Lineage Acute Lymphoblastic Leukemia with Only an NF1 Gene Pathogenic Variant.

Next-generation sequencing technology has improved molecular genetic analysis, and many molecular genetic studies have been utilized for diagnostic classification, risk stratification, and prognosis prediction of acute lymphoblastic leukemia (ALL). Inactivation of neurofibromin or Nf1, a protein derived from the NF1 gene, causes Ras pathway regulation failure, which is related to leukemogenesis. Pathogenic variants of the NF1 gene in B-cell lineage ALL are uncommon, and in this study, we reported a pathogenic variant that is not registered in any public database. The patient diagnosed with B-cell lineage ALL had no clinical symptoms of neurofibromatosis. Studies on the biology, diagnosis, and treatment of this uncommon disease, as well as other related hematologic neoplasms, such as acute myeloid leukemia and juvenile myelomonocytic leukemia, were reviewed. Biological studies included epidemiological differences among age intervals and pathways for leukemia, such as the Ras pathway. Diagnostic studies included cytogenetic, FISH, and molecular tests for leukemia-related genes and ALL classification, such as Ph-like ALL or BCR-ABL1-like ALL. Treatment studies included pathway inhibitors and chimeric antigen cell receptor T-cells. Resistance mechanisms related to leukemia drugs were also investigated. We believe that these literature reviews will enhance medical care for the uncommon diagnosis of B-cell lineage ALL.

Philadelphia-like acute lymphoblastic leukemia: the journey from molecular background to the role of bone marrow transplant-review article.

Philadelphia chromosome-like (Ph-like) ALL is a recent subtype of acute lymphoblastic leukemia. Although it does not express the BCR-ABL fusion gene, it has a behavior like true BCR/ABL1-positive cases. This subtype harbors different molecular alterations most commonly CRLF2 rearrangements. Most cases of Ph-like ALL are associated with high white blood cell count, high minimal residual disease level after induction therapy, and high relapse rate. Efforts should be encouraged for early recognition of Ph-like ALL to enhance therapeutic strategies. Recently, many trials are investigating the possibility of adding the tyrosine kinase inhibitor (TKI) to chemotherapy to improve clinical outcomes. The role and best timing of allogeneic bone marrow transplant in those cases are still unclear. Precision medicine should be implemented in the treatment of such cases. Here in this review, we summarize the available data on Ph-like ALL.

Rapid molecular response to dasatinib in Ph-like acute lymphoblastic leukemia patients with ABL1 rearrangements: case series and literature review.

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk subtype with a poor prognosis under conventional chemotherapy. Ph-like ALL has a similar gene expression profile to Philadelphia chromosome-positive (Ph+) ALL, but is highly heterogeneous in terms of genomic alterations. Approximately 10-20% of patients with Ph-like ALL harbor ABL class (e.g. ABL1, ABL2, PDGFRB, and CSF1R) rearrangements. Additional genes that form fusion genes with ABL class genes are still being researched. These aberrations result from rearrangements including chromosome translocations or deletions and may be targets of tyrosine kinase inhibitors (TKIs). However, due to the heterogeneity and rarity of each fusion gene in clinical practice, there is limited data on the efficacy of tyrosine kinase inhibitors. Here, we report three cases of Ph-like B-ALL with ABL1 rearrangements treated with the dasatinib backbone for the CNTRL::ABL1, LSM14A::ABL1, and FOXP1::ABL1 fusion genes. All three patients achieved rapid and profound remission with no significant adverse events. Our findings suggest that dasatinib is a potent TKI for the treatment of ABL1-rearranged Ph-like ALL and can be used as a first-line treatment option for such patients.

Ph-like acute lymphoblastic leukemia in adults: understanding pathogenesis, improving outcomes, and future directions for therapy.

Philadelphia (Ph)-like acute lymphoblastic leukemia (ALL) is a high-risk subgroup of B cell ALL with distinct genotypes, unified by gene expression profile similar to Ph-positive ALL, but lacking the BCR::ABL1 fusion. Ph-like ALL patients respond inadequately to conventional chemotherapy with higher rates of induction failure, persistent measurable residual disease, and lower survival rates compared to other B cell ALL subtypes. Considering Ph-like ALL's chemo-refractory nature, there is an interest in pursuing innovative therapeutic approaches to treat, including the combination of tyrosine kinase inhibitors with frontline regimens, and early introduction of novel antibody-drug conjugates and immunotherapies. Accurate diagnosis and disease-risk stratification are key to increase access for high-risk patients to allogeneic hematopoietic cell transplantation in their first complete remission. In this review, we will discuss our current knowledge of pathogenesis of Ph-like ALL, diagnostic strategies, as well as emerging data on new and current treatment strategies for this disease.

Single-cell heterogeneity and dynamic evolution of Ph-like acute lymphoblastic leukemia patient with novel TPR-PDGFRB fusion gene.

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a refractory and recurrent subtype of B-cell ALL enriched with kinase-activating rearrangements. Incomplete understanding of the heterogeneity within the tumor cells presents a major challenge for the diagnosis and therapy of Ph-like ALL. Here, we exhibited a comprehensive cell atlas of one Ph-like ALL patient with a novel TPR-PDGFRB fusion gene at diagnosis and relapse by using single-cell RNA sequencing (scRNA-seq). Twelve heterogeneous B-cell clusters, four with strong MKI67 expression indicating highly proliferating B cells, were identified. A relapse-enriched B-cell subset associated with poor prognosis was discovered, implicating the transcriptomic evolution during disease progression. Integrative single-cell analysis was performed on Ph-like ALL and Ph+ ALL patients, and revealed Ph-like specific B-cell subpopulations and shared malignant B cells characterized by the ectopic expression of the inhibitory receptor CLEC2D. Collectively, scRNA-seq of Ph-like ALL with a novel TPR-PDGFRB fusion gene provides valuable insights into the underlying heterogeneity associated with disease progression and offers useful information for the development of immunotherapeutic techniques in the future.

CAR-T cell therapy followed by allogenic hematopoietic stem cell transplantation yielded comparable outcome between Ph like ALL and other high-risk ALL.

It was previously believed that patients with Ph-like ALL had poorer prognosis compared with other B-ALL subgroups due to resistance to conventional chemotherapy and lack of targeted drugs. CAR-T therapy has been successfully applied in the treatment of relapsed and refractory B-ALL. Currently, there are few data on whether CAR-T therapy can alter the outcome of Ph-like ALL. Here we included 17 Ph-like, 23 Ph+ and 51 other B-ALL patients, who received autologous CAR T-cell therapy and subsequently allogenic stem cell transplantation. Patients in the Ph-like group and B-ALL-others group were younger that those in the Ph+ group (P=0.001). Ph-like and Ph+ ALL patients showed higher white blood cell counts at diagnosis (P=0.025). The percentage of patients with active disease before receiving CAR T-cells infusion was 64.7%, 39.1% and 62.7% in the Ph-like, Ph+ and B-ALL-others groups. The response rates to CAR-T therapy were 94.1% (16/17), 95.6% (22/23) and 98.0% (50/51) in the Ph-like, Ph+ and B-ALL-others groups. Measurable residual disease negative CR was achieved in 64.7% (11/17), 60.9% (14/23) and 54.9% (28/51) in the Ph-like, Ph+ and B-ALL-others groups, respectively. The estimated rates of 3-year overall survival (65.9%±16.5%, 59.7%±10.5% and 61.6%±7.3%, P=0.758) and 3-year relapse-free survival (59.8%±14.8%, 63.1%±10.5% and 56.3%±7.1%, P=0.764) were comparable among the Ph-like, Ph+ and B-ALL-others groups. Estimated 3-year cumulative relapse rate was 7.8%±0.6%, 23.4%±0.9% and 29.0%±0.4% (P=0.241). Our findings suggest that CART followed by allo-HSCT results in a comparable prognosis in Ph-like ALL and other high-risk B-ALL.Trial registration ClinicalTrials. gov, NCT03275493, Registered on September 7, 2017, prospectively registered and NCT03614858, Registered on August 3, 2018, prospectively registered.

Characterization of Philadelphia-like Pre-B Acute Lymphoblastic Leukemia: Experiences in Mexican Pediatric Patients.

Ph-like subtypes with CRLF2 abnormalities are frequent among Hispano-Latino children with pre-B ALL. Therefore, there is solid ground to suggest that this subtype is frequent in Mexican patients. The genomic complexity of Ph-like subtype constitutes a challenge for diagnosis, as it requires diverse genomic methodologies that are not widely available in diagnostic centers in Mexico. Here, we propose a diagnostic strategy for Ph-like ALL in accordance with our local capacity. Pre-B ALL patients without recurrent gene fusions (104) were classified using a gene-expression profile based on Ph-like signature genes analyzed by qRT-PCR. The expressions of the CRLF2 transcript and protein were determined by qRT-PCR and flow cytometry. The P2RY8::CRLF2, IGH::CRLF2, ABL1/2 rearrangements, and Ik6 isoform were screened using RT-PCR and FISH. Surrogate markers of Jak2-Stat5/Abl/Ras pathways were analyzed by phosphoflow. Mutations in relevant kinases/transcription factors genes in Ph-like were assessed by target-specific NGS. A total of 40 patients (38.5%) were classified as Ph-like; of these, 36 had abnormalities associated with Jak2-Stat5 and 4 had Abl. The rearrangements IGH::CRLF2,P2RY8::CRLF2, and iAMP21 were particularly frequent. We propose a strategy for the detection of Ph-like patients, by analyzing the overexpression/genetic lesions of CRLF2, the Abl phosphorylation of surrogate markers confirmed by gene rearrangements, and Sanger sequencing.

Efficacy of ruxolitinib in acute lymphoblastic leukemia: A systematic review.

Philadelphia-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk molecular subtype with a gene expression profile similar to Philadelphia-positive ALL, but not harboring the BCR-ABL1 gene fusion. We aimed to investigate the efficacy of target therapy with the Janus kinase inhibitor, ruxolitinib, in patients with Ph-like ALL and molecular signature of JAK-STAT signaling pathway. A systematic search of the literature was performed to identify reports concerning administration of ruxolitinib in Ph-like ALL patients. Additionally, Polish Pediatric ALL registries were searched for patients with Ph-like ALL treated with ruxolitinib. Extracted information included epidemiological background, somatic aberrations, treatment response, and patient outcome. After PubMed database search, twelve patients were identified, and one was identified in the Polish Pediatric ALL registry. In nine patients gene fusions affecting JAK2 (n = 7) and EPOR (n = 2) were detected. Surface overexpression of CRLF2 and IKZF1 deletions were observed in two and three patients, respectively. Induction failure occurred in all the patients. Therapy with ruxolitinib led to complete (n = 7) and partial (n = 2) remission, in three individuals no information was found. Based on the limited number of studies describing the efficacy of ruxolitinib as an additional compound administrated with standard ALL therapy, we conclude that this approach can be considered in patients with aberrations activating JAK-STAT pathway.

PAX5 fusion genes are frequent in poor risk childhood acute lymphoblastic leukaemia and can be targeted with BIBF1120.

BACKGROUND: Despite intensive risk-based treatment protocols, 15% of paediatric patients with B-Cell Precursor Acute Lymphoblastic Leukaemia (BCP-ALL) experience relapse. There is urgent need of novel strategies to target poor prognosis subgroups, like PAX5 translocated. METHODS: We considered 289 childhood BCP-ALL cases consecutively enrolled in Italy in the AIEOP-BFM ALL2000/R2006 protocols and we performed extensive molecular profiling, integrating gene expression, copy number analyses and fusion genes discovery by target-capture NGS. We developed preclinical strategies to target PAX5 fusion genes. FINDINGS: We identified 135 cases without recurrent genetic rearrangements. Among them, 59 patients (43·7%) had a Ph-like signature; the remaining cases were identified as ERG-related (26%), High-Hyperdiploid-like (17%), ETV6::RUNX1-like (8·9%), MEF2D-rearranged (2·2%) or KMT2A-like (1·5%). A poor prognosis was associated with the Ph-like signature, independently from other high-risk features. Interestingly, PAX5 was altered in 54·4% of Ph-like compared to 16·2% of non-Ph-like cases, with 7 patients carrying PAX5 fusions (PAX5t), involving either novel (ALDH18A1, IKZF1, CDH13) or known (FBRSL1, AUTS2, DACH2) partner genes. PAX5t cases have a specific driver activity signature, extending to multiple pathways including LCK hyperactivation. Among FDA-approved drugs and inhibitors, we selected Dasatinib, Bosutinib and Foretinib, in addition to Nintedanib, known to be LCK ligands. We demonstrated the efficacy of the LCK-inhibitor BIBF1120/Nintedanib, as single agent or in combination with conventional chemotherapy, both ex vivo and in patient-derived xenograft model, showing a synergistic effect with dexamethasone. INTERPRETATION: This study provides new insights in high-risk Ph-like leukaemia and identifies a potential therapy for targeting PAX5-fusion poor risk group. FUNDING: Ricerca Finalizzata-Giovani Ricercatori (Italian Ministry of Health), AIRC, Transcall, Fondazione Cariparo.

The current treatment approach to adolescents and young adults with acute lymphoblastic leukemia (AYA-ALL): challenges and considerations.

INTRODUCTION: AYA-ALL differs from pediatric ALL in terms of clinical, biological, psychosocial factors and access to care and has an inferior outcome. It is now being recognized that pediatric-inspired protocols are superior to adult protocols for this cohort, but given the lack of randomized trials, several questions remain unanswered. AREAS COVERED: In this review, we discuss how AYA-ALL is different from the pediatric ALL population, compare AYA-ALL with ALL in middle and older age adults, review the studies that have enrolled the AYA cohort, summarize risk-stratified and response-adapted approaches, describe the biological subtypes, and review the novel agents/approaches under evaluation. EXPERT OPINION: AYA-ALL is a complex and challenging disease that needs multidisciplinary and focused care. Well-designed clinical trials that focus on this cohort are needed to further improve the outcomes.

Case Report: Precision Medicine Target Revealed by In Vitro Modeling of Relapsed, Refractory Acute Lymphoblastic Leukemia From a Child With Neurofibromatosis.

Children with neurofibromatosis have a higher risk of developing juvenile myelomonocytic leukemia and acute myeloid leukemia, but rarely develop B-cell acute lymphoblastic leukemia (B-ALL). Through in-vitro modeling, a novel NF1 p.L2467 frameshift (fs) mutation identified in a relapsed/refractory Ph-like B-ALL patient with neurofibromatosis demonstrated cytokine independence and increased RAS signaling, indicative of leukemic transformation. Furthermore, these cells were sensitive to the MEK inhibitors trametinib and mirdametinib. Bi-allelic NF1 loss of function may be a contributing factor to relapse and with sensitivity to MEK inhibitors, suggests a novel precision medicine target in the setting of neurofibromatosis patients with B-ALL.