Adult B-cell Acute Lymphoblastic Leukemia Research Articles

Immunophenotypic Characteristics and Cytogenetic Analysis of Adolescent and Young Adult B-Cell Acute Lymphoblastic Leukemia: Correlations With Clinicopathological Parameters.

Introduction Acute lymphoblastic leukemia (ALL) has suboptimal survival rates for adolescents and young adults (AYA) as compared to children. Very limited studies have been conducted on AYA patients in India. This study aimed to identify the cytogenetic and immunophenotype characteristics of B-cell ALL (B-ALL) in AYA patients and determine its correlation with clinicopathological parameters in the Southern India region. Method The study was a prospective study conducted for three years, from June 2019 to May 2022, in India. Newly diagnosed 90 patients with AYA (13-40 years) ALL were recruited. A B-ALL diagnosis was made based on morphology with cytochemical stains and immunophenotype by flow cytometry (FCM). Cytogenetic analysis was also performed using karyotyping and fluorescent in situ hybridization to identify chromosomal aberrations. The cytogenetics results were correlated with immunophenotyping and clinicopathological characteristics. Variables were analyzed using the Mann-Whitney U test and Chi-square test using IBM SPSS Statistics for Windows, Version 20.0 (Released 2011; IBM Corp., Armonk, NY, USA). Results The mean age was 22.68 ± 8.06 years. It was observed that the most common structural chromosomal abnormality for AYA was t(9;22) in 14 (15%) cases, followed by 6q deletions in seven (8%) cases, t(1;19) in four (4%) cases, and t(12;17) and t(6;14) in two (2%) cases each. In addition, t(3;12), t(2;11), t(12;21), t(1;9), t(2;12), and t(X;10) were found in one (1%) case each. The most common numerical abnormality was hyperdiploidy (15; 17%), followed by hypodiploidy (10; 11%). Further, myeloid antigen expression of CD33 was the most common aberrantly expressed marker found in 20 (28%) cases, followed by CD15 in three cases (5%), CD13 in three (4%) cases, and CD11b in two (3%) cases. It was also observed that in Ph+ve cases, CD33 and CD13 were most commonly expressed in three (33%) and two (17%) cases, respectively. In contrast, in Ph-ve patients, their expressions were lesser at 17 (27%) and one (2%) cases, respectively. In addition, leukemia-associated immunophenotype pattern (LAIP) markers CD44 6 (86%) and CD123 5 (55%) were also found to be significantly associated with Ph+ve, whereas their values in the Ph-ve group were lesser at 25 (42%) and 9 (17%), respectively. Our data also showed that older age wassignificantly associated with Ph+ve with a median age of 30 years (p = 0.012). In comparison, the median age of Ph-ve was only 21 years. Conclusion Our study established that the incidence of cytogenetic abnormalities for AYA was consistent with previously reported data. This study reaffirms that Ph+ve cases have significant associations with MyAg (CD13), LAIP (CD123 and CD44), and older age for the South Indian population.

BRG1 promotes progression of B-cell acute lymphoblastic leukemia by disrupting PPP2R1A transcription

Despite advancements in chemotherapy and the availability of novel therapies, the outcome of adult patients with B-cell acute lymphoblastic leukemia (B-ALL) remains unsatisfactory. Therefore, it is necessary to understand the molecular mechanisms underlying the progression of B-ALL. Brahma-related gene 1 (BRG1) is a poor prognostic factor for multiple cancers. Here, the expression of BRG1 was found to be higher in patients with B-ALL, irrespective of the molecular subtype, than in healthy individuals, and its overexpression was associated with a poor prognosis. Upregulation of BRG1 accelerated cell cycle progression into the S phase, resulting in increased cell proliferation, whereas its downregulation facilitated the apoptosis of B-ALL cells. Mechanistically, BRG1 occupies the transcriptional activation site of PPP2R1A, thereby inhibiting its expression and activating the PI3K/AKT signaling pathway to regulate the proto-oncogenes c-Myc and BCL-2. Consistently, silencing of BRG1 and administration of PFI-3 (a specific inhibitor targeting BRG1) significantly inhibited the progression of leukemia and effectively prolonged survival in cell-derived xenograft mouse models of B-ALL. Altogether, this study demonstrates that BRG1-induced overactivation of the PPP2R1A/PI3K/AKT signaling pathway plays an important role in promoting the progression of B-ALL. Therefore, targeting BRG1 represents a promising strategy for the treatment of B-ALL in adults.

Overexpression of Nrf2 in bone marrow mesenchymal stem cells promotes B-cell acute lymphoblastic leukemia cells invasion and extramedullary organ infiltration through stimulation of the SDF-1/CXCR4 axis.

Tumor microenvironment (TME) represents the key factor inducing leukemia development. As stromal cells within the leukemia microenvironment, Bone Marrow Mesenchymal Stem Cells (BM-MSCs) can trigger leukemia progression under certain conditions. As a critical transcription factor, nuclear factor erythroid related factor 2 (Nrf2) can modulate antioxidant response and antioxidant enzyme gene expression, and prevent various oxidative changes. We previously identified a novel mechanism by which Nrf2 promotes leukemia resistance, providing a potential therapeutic target for the treatment of drug-resistant/refractory leukemias. However, the role of Nrf2 in BM-MSCs from B-cell acute lymphoblastic leukemia (B-ALL) patients has not been clearly reported. The present work focused on investigating the effect of Nrf2 overexpression within MSCs on leukemia cell invasion, extramedullary infiltration and proliferation as well as its downstream pathway. Through clinical sample detection, in vitro cell experiments and in vivo animal experiments, the role of Nrf2 within MSCs within adult B-ALL cell migration and invasion and its potential molecular mechanism was explored through transcriptome sequencing analysis, RT-PCR, Western blot, cell migration, cell invasion, lentivirus transfection and other experiments. Nrf2 was highly expressed in BM-MSCs from patients with B-ALL as well as in BM-MSCs co-cultured with leukemia cells. Overexpression of Nrf2 within MSCs significantly promoted leukemia cell migration, invasion and proliferation. The extramedullary organ infiltration rate in B-ALL model mice receiving the combined infusion of both cell types dramatically increased relative to that of leukemia cells alone, accompanied by the significantly shortened survival time. Mechanism study found that Nrf2 overexpression within MSCs promoted PI3K-AKT/ERK1/2 phosphorylation in the downstream pathway by activating SDF-1/CXCR4 axis, ultimately leading to extramedullary infiltration of leukemia cells. High Nrf2 expression with in MSCs enhances leukemia cell invasion and migration, which then accelerates infiltration in leukemic extramedullary organs. Targeting Nrf2 or inhibiting its downstream signal molecules may be the effective interventions for B-ALL patients treatment.

Center effect on allogeneic hematopoietic stem cell transplantation outcomes for B-cell acute lymphoblastic leukemia

This nationwide study retrospectively examined the center effect on allogeneic hematopoietic stem cell transplantation (allo-HSCT) for adult B-cell acute lymphoblastic leukemia. The cohort analyses were separated into Philadelphia chromosome (Ph)-positive and -negative cases. The patients were divided into low- and high-volume groups according to the number of allo-HSCTs at each facility. The primary endpoint was 5-year overall survival (OS). This study included 1156 low-volume and 1329 high-volume Ph-negative and 855 low-volume and 926 high-volume Ph-positive cases. In Ph-negative cases, 5-year OS was significantly higher in the high-volume centers at 52.7% (95% confidence interval [CI]: 49.9–55.5) versus 46.8% (95% CI: 43.8–49.7) for the low-volume centers (P < 0.01). Multivariate analysis identified high volume as a favorable prognostic factor (hazard ratio [HR]: 0.81 [95% CI: 0.72–0.92], P < 0.01). Subgroup analysis in Ph-negative cases revealed that the center effects were more evident in patients aged ≥40 years (HR: 0.72, 95% CI: 0.61–0.86, P < 0.01) and those receiving cord blood transplantation (HR: 0.62, 95% CI: 0.48–0.79, P < 0.01). In Ph-positive cases, no significant difference was observed between the high and low-volume centers for 5-year OS (59.5% [95% CI: 56.2–62.7] vs. 54.9% [95% CI: 51.3–58.3], P = 0.054). In multivariate analysis, center volume did not emerge as a significant prognostic indicator. This study showed center effects on survival in Ph-negative but not in Ph-positive cases, highlighting the heterogeneity of the center effect in allo-HSCT for B-cell acute lymphoblastic leukemia. Collaborative efforts among transplant centers and further validation are essential to improve outcomes.

STAT5 phosphorylation plus minimal residual disease defines a novel risk classification in adult B-cell acute lymphoblastic leukaemia.

The dysregulation of the Janus family tyrosine kinase-signal transducer and activator of transcription (JAK-STAT) is closely related to acute lymphoblastic leukaemia (ALL), whereas the clinical value of phosphorylated STAT5 (pSTAT5) remains elusive. Herein we performed a prospective study on clinical significance of flow cytometry-based pSTAT5 in adult B-ALL patients. A total of 184 patients were enrolled in the Precision-Classification-Directed-Target-Total-Therapy (PDT)-ALL-2016 cohort between January 2018 and December 2021, and STAT5 phosphorylation was detected by flow cytometry at diagnosis. Based on flow-pSTAT5, the population was classified into pSTAT5low (113/184, 61.1%) and pSTAT5high (71/184, 38.9%). Overall survival (OS) and event-free survival (EFS) were inferior in pSTAT5high patients than in those with pSTAT5low (OS, 44.8% vs. 65.2%, p = 0.004; EFS, 23.5% vs. 52.1%, p < 0.001), which was further confirmed in an external validation cohort. Furthermore, pSTAT5 plus flow-based minimal residual disease (MRD) postinduction defines a novel risk classification as being high risk (HR, pSTAT5high + MRD+), standard risk (SR, pSTAT5low + MRD-) and others as moderate-risk group. Three identified patient subgroups are distinguishable with disparate survival curves (3-year OS rates, 36.5%, 56.7% and 76.3%, p < 0.001), which was confirmed on multivariate analysis (hazard ratio 3.53, p = 0.003). Collectively, our study proposed a novel, simple and flow-based risk classification by integrating pSTAT5 and MRD in favour of risk-guided treatment for B-ALL.

Blinatumomab consolidation for adult B-cell acute lymphoblastic leukemia in first and second complete remission

Blinatumomab consolidation for adult B-cell acute lymphoblastic leukemia in first and second complete remission

Blinatumomab Therapy for Low Level Minimal Residual Disease Detected By Next-Generation Sequencing in Adult B-Cell Acute Lymphoblastic Leukemia

Blinatumomab Therapy for Low Level Minimal Residual Disease Detected By Next-Generation Sequencing in Adult B-Cell Acute Lymphoblastic Leukemia

Transcriptome analysis of primary adult B-cell lineage acute lymphoblastic leukemia identifies pathogenic variants and gene fusions, and predicts subtypes for in depth molecular diagnosis.

B-cell acute lymphoblastic leukemia (B-ALL) is classified into subgroups based on known driver oncogenes and molecular lesions, including translocations and recurrent mutations. However, the current diagnostic tests do not identify subtypes or oncogenic lesions for all B-ALL samples, creating a heterogeneous B-ALL group of unknown subtypes. We sorted primary adult B-ALL cells and performed transcriptome analysis by bulk RNA sequencing (RNA-seq). Transcriptomic analysis of an adult B-ALL cohort allowed the classification of four patient samples with subtypes that were not previously revealed by standard gene panels. The leukemia of two patients were of the DUX4 subtype and two were CRLF2+ Ph-like B-ALL. Furthermore, single nucleotide variant analysis detected the oncogenic NRAS-G12D, KRAS-G12D, and KRAS-G13D mutations in three of the patient samples, presenting targetable mutations. Additional oncogenic variants and gene fusions were uncovered, as well as multiple variants in the PDE4DIP gene across five of the patient samples. We demonstrate that RNA-seq is an effective tool for precision medicine in B-ALL by providing comprehensive molecular profiling of leukemia cells, identifying subtype and oncogenic lesions, and stratifying patients for appropriate therapy.

Recommendations for the treatment and management of adult B-Cell acute lymphoblastic leukemia in Asia-Pacific: Outcomes from a pilot initiative.

The outcomes of adult B-cell acute lymphoblastic leukemia (ALL) remain poor. Recent advancements in the field of leukemia research show potential for improved patient care. However, the adoption of research findings into clinical practice is fraught with practice- and country-specific challenges. The continued addition of new findings warrants critical evaluation for the feasibility of incorporation into clinical practice. A uniform set of evidence-based guidelines can favorably assist physicians in making optimal clinical decisions. Such a resource may also serve as a reference point for strategic planning of initiatives aimed at addressing critical barriers in the optimal management of B-cell ALL. This initiative was undertaken to seek a collaborative perspective and understand the existing challenges. Concordance-based recommendations were outlined through a systematic discussion on various aspects of treatment and management of adult B-cell ALL. The outcomes and experiences gained from this exercise will serve as a foundation for future efforts encompassing the more granular aspects of the management of B-cell ALL across the Asia-Pacific region.

SPAG6 regulates cell proliferation and apoptosis via TGF-β/Smad signal pathway in adult B-cell acute lymphoblastic leukemia.

Adult B-cell acute lymphoblastic leukemia (B-ALL) prognosis remains unsatisfactory, and searching for new therapeutic targets is crucial for improving patient prognosis. Sperm-associated antigen 6 (SPAG6), a member of the cancer-testis antigen family, plays an important role in tumors, especially hematologic tumors; however, it is unknown whether SPAG6 plays a role in adult B-ALL. In this study, we demonstrated for the first time that SPAG6 expression was up-regulated in the bone marrow of adult B-ALL patients compared to healthy donors, and expression was significantly reduced in patients who achieved complete remission (CR) after treatment. In addition, patients with high SPAG6 expression were older (≥ 35years; P = 0.015), had elevated white blood cell counts (WBC > 30 × 109/L; P = 0.021), and a low rate of CR (P = 0.036). We explored the SPAG6 effect on cell function by lentiviral transfection of adult B-ALL cell lines BALL-1 and NALM-6, and discovered that knocking down SPAG6 significantly inhibited cell proliferation and promoted apoptosis. We identified that SPAG6 knockdown might regulate cell proliferation and apoptosis via the transforming growth factor-β (TGF-β)/Smad signaling pathway.

Acute lymphoblastic leukemia in young adults: which up-front treatment?.

Significant improvements have occurred for adolescent and young adult (AYA) B-cell acute lymphoblastic leukemia (B-ALL) patients following the widespread adoption of "pediatric-inspired" treatment regimens for AYA patients cared for in adult oncology settings. However, for AYA patients, aged 15 to 39, an outcomes gap remains in B-ALL, necessitating the incorporation of novel therapies into up-front treatment regimens. As a result, clinical trial enrollment remains the current standard of care for AYA B-ALL across disease subtypes when available and accessible. Currently, several up-front trials are looking to incorporate the use of inotuzumab, blinatumomab, and chimeric antigen receptor T-cell therapy into existing chemotherapy backbones for AYA patients, as well as tyrosine kinase inhibitors for both Philadelphia-positive (Ph+) and Ph-like B-ALL. In addition to ongoing attempts to improve up-front treatments by incorporating immunotherapy and targeted approaches, the increased use of next generation sequencing for measurable residual disease evaluation has led to superior risk-stratification and a decreased need to pursue consolidative hematopoietic stem cell transplantation during the first complete remission for many patients.

Establishing Costs for Commercial Chimeric Antigen Receptor T-Cell (Tisagenlecleucel; Kymriah) in Children and Young Adult B-Cell Acute Lymphoblastic Leukemia; A Merged Analysis from the Prwcc and PHIS

Background: Chimeric antigen receptor (CAR) T cell therapy has achieved remarkable efficacy in children and young adult (CAYA) B-cell acute lymphoblastic leukemia (B-ALL). Nonetheless, this therapy is highly personalized, technically complex, and costly to manufacture. The USA FDA approved the first CAR T cell therapy (Kymriah) in Aug 2017, for relapsed/refractory CAYA B-ALL. The list price of Kymriah is $475,000, not accounting for costs related to delivery of care, inpatient hospitalization, toxicity management or follow-up. A half-decade of clinical experience has amassed since commercialization, yet financial analyses remain sparse. Here, we conduct the first study to understand costs for commercial CAR in CAYA B-ALL. Methods: Ten centers participating in both the Pediatric Real-world CAR Consortium (PRWCC) and Pediatric Health Information System (PHIS; Children's Hospital Association, Lenexa, KS) were eligible for study (08/2017-03/2020). Clinical data from the PRWCC database was merged with PHIS using age, diagnosis, center and lymphodepletion dates. Utilizing center and year specific charge-to-cost ratio, PHIS provided data for inpatient admission associated costs, but not outpatient care. For patients that were infused outpatient and subsequently admitted, only inpatient cost was available and analyzed for the first 60 days post-infusion. For patients that were infused inpatient, cost was calculated from the first day of admission for lymphodepletion or Kymriah infusion to 60 days post-infusion. The 60-day follow up was chosen as most of the clinical activity and toxicities occur within the 60 days post-infusion. Each patient was assigned a cost of $475,000 for Kymriah (list price). For the subset of patients who underwent allogeneic hematopoietic cell transplantation (alloHCT) following Kymriah, the median inpatient cost was assessed for 1-year post-alloHCT. Cost data was analyzed as medians and ranges. Univariable and multivariable logistic regression models were used to identify factors associated with the higher median cost associated with inpatient admissions. Results: 109 Kymriah-recipients were included. Patient characteristics are listed in Table 1. The incidence of grade 1-2 and ≥3 CRS was 42% and 23%, respectively, and grade 1-2 and ≥3 ICANS was 17% and 6%, respectively. Relapse/refractory disease at day 30 and 60 post-Kymriah infusion was 11% and 16%, respectively. AlloHCT was performed in 17 (16%) patients. Median time to alloHCT from Kymriah infusion was 148 days (36-354). The median number of admissions was 1 (0-5) and median length of all hospitalization was 18 days (0-69), 99% patients required inpatient admission. Thirty-six patients (33%) required intensive care unit (ICU) admission with a median ICU stay of 5 days (1-24). The median total cost (Kymriah + inpatient cost) per patient was $615,845 ($475,000-1,578,321). Breakdown of median total cost (excluding Kymriah) was: room/board $33,676 ($0-454,256), pharmacy $65,854 ($0-515,132), laboratory/pathology cost $10,496 ($0-201,900) and other cost $8,204 ($0-573,163). One-year median cost associated with inpatient admissions for alloHCT was $556,712 ($105,670-1,919,275), combined median cost associated with Kymriah + alloHCT was $1,263,316 ($696,768-2,404,447). Factors associated with higher inpatient cost were public insurance ($96,287, p=0.002); inpatient Kymriah infusion ($395,182, p&amp;lt;0.001); CRS grade≥3 ($342,176, p&amp;lt;0.001); ICANS grade ≥3 ($354,013, p=0.010); ICU stay ($346,737 p&amp;lt;0.001). Multivariable analysis demonstrated that only inpatient infusion of Kymriah significantly associated with higher cost (Table 2). Conclusion: In this cost analysis across CAYA receiving Kymriah, we describe the total inpatient treatment-associated cost, with inpatient infusion emerging as a main driver of cost. With increased clinical experience, outpatient infusions and early interventions to avoid high-grade toxicity and ICU-level care have become more common and potentially more cost-effective. Our data justifies efforts to deliver Kymriah in the outpatient setting, when safe and feasible, and to provide support systems to facilitate this. Additionally, Kymriah drug cost accounts for the bulk (73%) of the overall median cost, highlighting that efforts to lower drug costs may permit enhanced access globally.

BRG1 Regulates Adult B-Cell Acute Lymphoblastic Leukemia Proliferation and Apoptosis By Interacting with c-MYC and Activating PI3K/AKT Pathway

Background and objective：Adult B-cell acute lymphoblastic leukemia（B-ALL）has historically had a dismal prognosis, with limited treatment options and cure rates less than 40%. Only 25% of patients older than 50 years old were alive 5 years after diagnosis, highlighting the need for further improvements in treatment for older adult patients (≥40 years). Recently years, genome profiling revealed that cancer cells frequently depend on chromatin regulatory activities to maintain a malignant phenotype and proliferation. Brahma-related gene 1（BRG1）, a core catalytic ATPase subunits of the SWI/SNF chromatin remodelling complex, has been reported to support oncogenic transcriptional program and sustain leukaemogenic transformation in leukemia. However, the specific role and mechanisms of BRG1 in B-ALL development and progression remains largely unknown. Therefore, elucidating the underlying maintenance mechanisms is essential to develop novel effective treatment strategies. Methods：For clinical sample, we analyzed the mRNA expression level of BRG1 in newly diagnosed B-ALL patients(n=576) and healthy donors(n=74) in the GSE13159 subset from GEO database. Then, quantitative reverse transcription-PCR (RT-PCR) and Western blot were used to detect the expression of BRG1 in 38 newly diagnosed B-ALL patients and 25 healthy donors in our department. For further exploring the effects of BRG1 on B-ALL , lentiviral transfection were used to knock down BRG1 in SUP-B15 and Nalm-6 cells and overexpress BRG1 in RS4:11 cell, and CCK-8, Edu, clone formation assay, cell cycle, apoptosis, IF, RT-PCR and Western Blot were used to detect the effects. In addition, TMT proteomics was used to analyze the differential proteins between sh-ctrl and sh-BRG1 of Nalm-6 cell. Western Bolt was used to detect the changes of key proteins in related pathways. Results: Our investigation of SMARCA4 revealed that BRG1 is over-expressed in the 576 newly diagnosed B-ALL patients from GSE13159 dataset, as well as in 38 of our department. Downregulated BRG1 inhibited growth and increased the apoptosis of ALL, while ectopic expression of BRG1 showed the opposite effects. Mechanistically, TMT proteomics analysis and vitro experiments further revealed that BRG1 exerted these functions through its interaction with c-MYC and regulated the expression of CDK4/6, BCL-2 and BCL-xl. Conclusion: Our study demonstrates that BRG1 upregulation is closely associated with proliferation and anti-apoptosis in adult B-ALL.

Diagnostic Utility of Comprehensive RNA-Seq Analysis in Adult B-ALL

Introduction Adult B-cell acute lymphoblastic leukemia (B-ALL) comprises 75% of adult ALL cases. The classification and risk stratification of patients have conventionally relied on cytogenetics analysis. However, cytogenetics has limitations due to its reliance on metaphase cells, which can mitigate classification accuracy. In recent years, transcriptome sequencing (RNA-seq) of large pediatrics ALL cohorts has expanded the number of recurrent gene fusions recognized as disease defining events and informed risk stratification [Brady et al. 2022, Mullighan et al. 2017]. This study aims to evaluate the diagnostic utility of RNA-seq for clinical subtype classification in adult B-ALL in a large representative cohort. Methods The study cohort comprised 338 adult patients (25-65 years) with newly diagnosed ALL (UKALL14, ISRCTN66541317, NCT01085617). Paired-end RNA-seq data at 60 Million reads per sample were generated. Analysis focused on the detection of disease-defining gene fusions and gene expression signatures. Three RNA fusion callers (FusionCatcher, FuSeq, and STAR-Fusion) and three expression-based classifiers (ALLSorts, ALLspice, and ALLCatchR) were used for consensus fusion calling and expression-based classification, respectively [Nicorici et al. 2014, Vu et al. 2018, Haas et al. 2019, Schmidt et al., Mäkinen et al., Bader et al. 2022]. Integration of classification results from expression-based classifiers and the consensus gene fusions provides 4 levels of RNA-derived subtype information, denoted as “RNA evidence” in this study. These RNA-seq based classification results were compared with clinical cytogenetics findings. Results Out of 338 samples in this cohort, cytogenetics unequivocally classified 73% (246/338) of the samples. By integrating RNA expression-based classification with fusion subtypes, we confidently classified 87% (295/338) of the cohort with at least 2 levels of RNA evidence. In total, consensus gene fusions were identified in 74% (249/338), while expression-based classifiers assigned a confident subtype to 82% (319/338). Subsequently, we compared cytogenetics with RNA-seq derived classification and found a high concordance of 98% (240/246) between the two approaches. Only 6 (&amp;lt;2%) samples with cytogenetics subtypes were not classified by RNA-seq, attributed to specific subtype characteristics (near-haploid) or lower RNA purity/quality. 27% (92/338) of subjects were not classified by cytogenetics (31 missing/failed and 61 indeterminate cytogenetics). Of the 31 samples with failed/missing cytogenetics, RNA-seq confidently assigned a class in 74% (23/31). For the remaining 61 cases with indeterminate cytogenetic (complex/other), RNA-seq resolved classification in 74% (45/61). Taken together, this improved the classification for 20% (68/338) of the entire cohort that was previously unclassified through cytogenetics. Notably, RNA-seq-exclusive findings were enriched in subtypes like DUX4, PAX5alt, and ZNF384, which are challenging for cytogenetics to discern. Importantly, integration of RNA-seq with cytogenetics led to a confident subtype classification for 93% of the cohort (314/338), a significant improvement over the initial 73% based on cytogenetics alone. Conclusions In conclusion, our study highlights the relevance of integrated RNA-seq analysis for reliable and comprehensive subtype classification in adult B-ALL. The high concordance between cytogenetics and RNA-derived subtypes underscores their complementary roles, providing valuable insights into disease mechanisms and guiding personalized treatment strategies.

Mutually-Exclusive Pathways between IKZF1plus and RAS Mutations and TP53 double-Hit Alterations Lead Relapse in B-Other, Ph-like and Hyperdiploidy Genetic Groups in Adult B-Cell Acute Lymphoblastic Leukemia

Introduction: Adult B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is a hematologic malignancy characterized by a high genetic heterogeneity and high relapse rate. Despite treatment advances have led to high cure rates in pediatric BCP-ALL (90%), improving survival in adults remains a challenge. Identification of genetic alterations driving relapse and both new prognostic and therapeutic biomarkers are important to improve survival in adults with BCP-ALL. Aim: To identify genetic alterations that lead to relapse in adult BCP-ALL patients (18-72 years) based on the tumor genetic landscape. Methods: Forty-five adult BCP-ALL patients (median age: 43 years; range 18-72 years) were studied at diagnosis and relapse by massive sequencing using a custom panel that allows detection of single nucleotide variants (SNVs) and insertions/deletions (INDELs) in 150 genes involved in BCP-ALL, in addition to copy number variations (CNVs), gene fusions and aneuploidy. Thirty-eight percent of patients belonged to the BCP-other ALL group, 16% were Philadelphia-positive (Ph+), 16% were classified as Philadelphia-like (Ph-like), 11% belonged to the high hyperdiploidy group, 8% had KMT2A rearrangements ( KMT2Ar), 4% TCF3::PBX1 fusion, 3% showed hypodiploidy, 2% low hyperdiploidy and 2% de novo MYC and BCL2 double-hit. Patients were treated according to the Spanish Adult-PETHEMA high-risk ALL protocols. Results: The most frequently deleted gene at diagnosis was IKZF1 (25/45, 56%). Among these cases, 72% (20/25) had IKZF1plus genetic profile, characterized by co-occurrence of IKZF1 deletions with at least one deletion in CDKN2A/B, PAX5 or PAR1, without ERG deletion. The IKZF1plus genetic profile was associated with specific genetic subgroups: Ph+ (5/7, 71%), Ph-like (5/7, 71%) and B-other (10/17, 59%). Moreover, it was significantly related with the presence of minimal/measurable residual disease (MRD) after induction (16/18, 89%) p &amp;lt; 0.001 and persistence at relapse in most patients (18/20, 90%; p &amp;lt; 0.001). Interestingly, among those 5 patients initially diagnosed with IKZF1 deletion but who did not meet the criteria for the IKZF1plus profile, 2 of them acquired the IKZF1plus profile at relapse. This suggests a possible cooperation of these genetic deletions contributing to therapy resistance and disease progression in these genetic subgroups. Eighty-six percent (6/7) of Ph+ patients who received imatinib treatment presented ABL1 mutations that were detected exclusively at relapse. Of these cases, 67% (4/6) were also associated with IKZF1plus at relapse (Figure 1A). Two mutually exclusive genetic patterns were identified at relapse in adult B-other and Ph-like patients. Thus, patients with IKZF1plus profile did not show RAS pathway mutations (59% and 57%, respectively), while patients with RAS pathway mutations lack in IKZF1plus profile (18% and 29%, respectively) (Figure 1B). Moreover age-related differences in the adult B-other ALL patient group were observed. The presence of mutations in RAS pathway was associated with younger age (&amp;lt;40 years) (3/10, 30% vs. 0/7, 0%), whereas older patients (≥40 years) predominated in the IKZF1plus profile (6/7, 86% vs. 3/10, 30%). TP53 alterations were detected at diagnosis and/or relapse in 11 patients (24%), most of which (9/11, 82%) had a heterozygous mutation plus a deletion or a homozygous mutation (double-hit). The high hyperdiploidy subgroup was enriched in TP53 mutations (4/5, 80%), most of which were already present at diagnosis (3/4, 75%). These findings indicate that genetic biomarkers usually linked to a favorable prognosis, such as high hyperdiploidy, can be associated with unfavorable genetic markers, leading to poorer outcomes in this group of patients (Figure 1C). Both the IKZF1plus profile and TP53 alterations were associated with poorer overall survival (OS) rates (P=0.034 and P=0.040, respectively) in adult BCP-ALL (Figure 2). Conclusion: Our results highlight the clinical importance of the TP53 alterations and the IKZF1plus profile as prognostic factors in adult BCP-ALL, suggesting they might help guiding more personalized therapeutic strategies to improve outcomes in this group of BCP-ALL patients. Grants: SACYL(GRS2386/A/21,GRS2385/A/21,GRS2527/A/22,GRS2506/A/22), JCyL SA118P20, FMM21/002 AP176752021, Pfizer 69383919.

Impact of Salvage and Bridging Therapy in Adult Patients with Refractory B-Cell Acute Lymphoblastic Leukemia (B-ALL) Referred for Anti-CD19 CAR T-Cell Therapy: An Intention to Treat Analysis

Background: Prognosis of relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (ALL) is poor, particularly after allogeneic hematopoietic cell transplantation (alloHCT). In this setting, several CAR T-cell products targeting CD19 (CART19) have been able to achieve complete response (CR) rates of 70 to 90%. However, a significant proportion of these patients still relapse. Several studies focus on the effect of the CART19 product on efficacy, however, information on how salvage therapy (ST) and bridging therapy (BT) can modulate the outcomes of CART19 therapy is scarce. Methods: We report the outcomes of all adult patients with R/R B-ALL intended for treatment (aphaeresis performed) with available CART19 products in a single institution from Jul 2017 to Jul 2023. This includes patients intended to receive the academic varnimcabtagene autoleucel (var-cel) in the CART19-BE-01 trial and the consecutive compassionate use and hospital exemption programs, as well as with commercially available tisagenleuceucel (tisa-cel). Lymphodepletion was performed with fludarabine (90 or 120 mg/m 2) and cyclophosphamide (900 or 1000 mg/m 2), followed by the infusion var-cel or tisa-cel, respectively. We analyzed all ST (treatment administered after last relapse before CART19-apheresis) and BT (treatment administered after apheresis and before CART19 infusion) performed, and analyzed the impact of BT on PFS and OS after apheresis. Results: A total of 74 adult B-ALL patients underwent leukapheresis and CART19 (var-cel/tisa-cel) production. At screening patients had a median age of 34 years (19-78), 45% were females, with a median of 3 prior lines of therapy (2-7) including inotuzumab (69%), blinatumomab (27%) and allo-HCT (84%). After last relapse, 92% of patients received ST with a median of 1 (0-3) treatment line, including inotuzumab (48%), high-dose chemotherapy (28%), low-dose chemotherapy (21%), TKIs (12%), blinatumomab (9%), radiotherapy (7%) and DLIs (4%). The overall response to ST prior apheresis was MRD-negative CR (28%), MRD-positive CR (22%), partial response (4%) and progressive disease (PD) in 46%. After apheresis was secured, BT was performed in 76% of patients with a median of 1 (0-2) bridging line, including low-dose chemotherapy (44%), intrathecal therapy (23%), high-dose chemotherapy (15%), TKIs (15%), inotuzumab (14%), radiotherapy (3.5%), blinatumomab (1.8%) and DLIs (1.8%). BT was not administered in 24% (8/74) of patients mainly due to morphological remission at screening (83%) and frailty (11%). The overall response to BT prior CART19 infusion was MRD-negative CR (31%), MRD-positive CR (12%), partial response (7%) and progressive disease (47%), with a 3% treatment related mortality (TRM) events attributed to BT. Inotuzumab administration occurred either as ST or BT to CART19 in 86% of patients (the remaining 14% was previouly given as bridge to allo-HCT), and was able to achieve MRD-negative CR in 42% of patients. The overall control of the disease after BT either worsened (51%), remained similar (14%), or improved (35%). After this, 12% (n=9) of CART19 treatments were not performed due to progressive disease (33%), TRM (22%), therapeutic alternative (22%), and production failure (11%). Infused patients achieved an MRD-negative CRR of 90% with a median PFS of 11,2 months. There were no differences in OS between patients with ≥5% or &amp;lt;5% bone marrow (BM) blast counts either before apheresis (ITT, figure 1) or after BT prior to CART19 infusion. However, despite the lack of apparent impact of this disease burden categorization on the OS at both timepoints, a statistically significant difference was observed after categorizing patients regarding the response to BT (figure 2), with a median PFS of 6.6 vs 18.6 months if the overall disease status of the patients either worsened or remained stable/improved after BT (p=0.0002). Conclusions: To the best of our knowledge this could be one of the first studies focusing on the impact of ST and BT in adult patients with R/R B-ALL referred for CART19 therapy. These results suggest that the potentially synergistic impact of bridging therapy may be mediated more by the modulation exerted by BT on the proliferative kinetics of the disease rather than on the absolute tumour burden of the patient. More detailed results on the independent impact of each type of BT will be provided in the final presentation.

Venous Thromboembolism (VTE) in Post-CAR-T Patients - a Meta-Analysis of Phase 2 &amp; 3 Clinical Trials

Introduction: Chimeric Antigen Receptor T- cells (CAR-T) therapy is genetically engineered T cells that provide durable responses for patients with certain hematological malignancies. CAR-T therapy continues to expand as a treatment option for various malignant conditions. ICANS and CRS, a clinical syndrome of neurological symptoms, fever, hypotension, and hypoxia, are potentially serious complications of post-CAR-T. Both of these complications can, in turn, increase the risk of VTE. Only a few case reports and retrospective analyses have described the risk of VTE. The primary objective of this systematic review and meta-analysis is to review the data from phase 2 and 3 clinical trials to determine the incidence and risk of VTE post-CAR-T treatment. Material and methods: The National Institute of Health (NIH) library, Cochrane Library, and ClinicalTrials.gov database were scoured for all phase 2 and phase 3 clinical trials, completed by March 7, 2023, on CAR-T cell therapy. Two reviewers independently verified the results. Several data points were extracted. A biostatistician conducted the meta-analysis using the Meta package in the R version 4.1.2 (Balduzzi, Rücker, &amp; Schwarzer, 2019; R Core Team, 2021). The endpoints of interest were the odds ratio and relative risk of developing VTE while in CRS using the Mantel-Haenszel method. Result: Nine phase 2 &amp; 3 trials (Seven phase 2 and two phase 3 trials) were identified and were included in our study. The incidence of CRS, ICANS, and VTE was obtained from the toxicity list and supplemental data for analysis. Only KTE-X19 studying Brexucabtagene (Tecartus) for relapsed or refractory adult B-cell acute lymphoblastic leukemia and Relapsed or refractory Mantle-Cell Lymphoma mentioned the incidence of one and three cases of VTE, respectively, in patients getting CAR-T cell therapy. The total number of patients reviewed from these studies was 1784, of which 1017 received CAR-T cell therapy. The odds of VTE were 99.9995% lower than CRS, OR = 0.0005, 95% CI [0.0001, 0.0017] in patients receiving a CAR-T infusion, p &amp;lt; .0001. The Relative risk of VTE was 0.0050, 95% CI [0.0019, 0.0132]. The test of heterogeneity (p = .0430) suggests the presence of heterogeneous results. The heterogeneity statistic I2 is 49.86%, indicating moderate heterogeneity (percentage of variation across studies due to heterogeneity rather than chance). The odds of VTE were 99.9999% lower than no VTE, OR = 0.0001, 95% CI [0.0001, 0.0004], p &amp;lt;.0001 with a Relative risk of 0.0039, 95% CI [0.0015, 0.0105]. Discussion: CRS is a known risk factor for VTE. In patients with underlying malignancy undergoing CAR-T therapy, the risk can be much higher than those without malignancy who develop CRS for other reasons. In a retrospective single-center observational study, Hashmi et al. reported an 11% incidence of VTE in lymphoma patients treated with CAR-T directed against the CD-19 receptor. Our systematic review and metanalysis didn't find a statistically increased risk of VTE in the patients getting CAR-T cell therapy despite the risk of CRS/ ICANS and underlying malignancy. The findings suggest that the thrombotic risks are either low or were not reported in the interval specified in the studies. The need for thromboprophylaxis must be made on a case-by-case basis, factoring in other risk factors such as underlying disease, cytopenia, and other medical comorbidities. Conclusion: The Incidence of VTE is low following CAR-T therapy despite the risks, and the need for thromboprophylaxis should be based on individual patient characteristics. Patient selection, exclusion criteria, and short follow-up periods following phase 2 trials might impact our study results. In a long-term phase 3 trial, collecting data for VTE may be needed to appropriately stratify patients for their VTE risk so that an appropriate thromboprophylaxis can be recommended to prevent an additional serious complication post-CAR-T.

Blinatumomab Therapy for Low Level Minimal Residual Disease Detected By Next-Generation Sequencing in Adult B-Cell Acute Lymphoblastic Leukemia

Introduction: Blinatumomab, a bi-specific T-cell engager, has shown clinical benefit in patients with relapsed-refractory and hematologic complete remission with minimal residual disease (MRD)-positive Acute Lymphoblastic Leukemia (ALL). The BLAST trial (Gökbuget N et al., Blood. 2018) demonstrated improved overall survival (OS) and disease-free survival (DFS) in patients with MRD-positive disease (≥0.1%) who achieved MRD response with Blinatumomab. We sought to evaluate the utility of Blinatumomab in low levels of MRD (&amp;lt;0.1%) using clonoSEQ with a sensitivity of (0.0001%). Methods: Adult (18+) B- ALL patients that underwent treatment for B-cell ALL at Norris Comprehensive Cancer Center (NCCC) between 2016 and 2022 who had residual disease tracked using the Next Generation Sequencing (NGS)-based clonoSEQ assay (Adaptive Biotechnologies, Seattle, WA) were included. Patients who received Blinatumomab for MRD positivity were included only if they had a tracked clonoSEQ sequence within one month before starting treatment. Patients who didn't receive Blinatumomab were included if they had an MRD-positive clonoSEQ report. Those who were relapse/refractory when found to be MRD positive were excluded. Cumulative incidence of relapse (CIR) was evaluated using competing risk regression (Fine-Gray method), with death as a competing outcome. At the same time, OS and DFS were analyzed using Cox proportional hazards model. The start time was set to the date of the MRD report, and patients were censored until the last follow-up. Confounder-adjusted KM curves were calculated using direct standardization. Results: 47 patients were included with a median age at diagnosis of 45 years (range: 21-70). Most were Hispanic (N = 33, 70.2%), and the median follow-up time was 12 months. The 3-year OS, DFS, and CIR were 95.4% (95% CI 89.3-100%), 75.1% (95% CI 60.4-93.5%), and 20.3% (95% CI 7.2-38.0%). Twenty-six patients were treated with Blinatumomab (median two cycles, range 1-9), with most (N= 14, 53.8%) having low levels of MRD (&amp;lt;0.1%). Fourteen patients (53.8%) achieved MRD negativity with a median time to MRD negativity of 3.1 months. There were no relapses or death in patients who achieved MRD negativity in the treated group. However, non-responders with Blinatumomab had one death and two relapses. All patients continued Maintenance therapy after receiving Blinatumomab and did not proceed with the transplant. The patients who received Blinatumomab were more likely to be MRD positive on multiparameter flow cytometry (MFC) (60.0% vs. 28.6%, P = 0.042) but had a similar distribution of patient age, treatment type, and receipt of transplant. Additionally, there was a trend toward increased median percent residual cells on clonoSEQ (0.018% vs. 0.003% P =0.244) and flow (0.02% vs 0% P =0.066) in the Blinatumomab treatment group. On univariate analysis, significant predictors of CIR and DFS were flow percent (DFS: HR = 1.54; 95% CI 1.07-2.23; P = 0.019; CIR: HR = 1.83; 95% CI 1.38-2.41; P&amp;lt;0.001) and clonoSEQ residual cell count(DFS: HR = 1.58; 95% CI 1.04-2.41; P = 0.031, CIR: HR = 1.88; 95% CI 1.18-2.97 P=0.008). When controlling for the number of residual cells on close, patients who received Blinatumomab had significantly better CIR(HR = 0.11; 95% CI 0.02-0.69; P = 0.019) and a trend towards improved DFS(HR = 0.21; 95% CI 0.04-1.28; P = 0.092), but no difference in OS. On subgroup analysis of the 31 patients with low levels of MRD (&amp;lt;0.1%), there was no improvement in DFS for patients who were treated with Blinatumomab (HR = 0.41; 95% CI 0.04-3.91; P = 0.44). Of those with low levels of MRD, only two relapsed, and both did not receive Blinatumomab. Conclusions: In B cell ALL, Blinatumomab may offer a CIR benefit to patients with low levels of MRD as detected on clonoSEQ.

Unraveling the Mechanism of Action of Bispecific T-Cell Engagers in B-Cell Acute Lymphoblastic Leukemia Using Advanced Single-Cell Multiomics

Background Bispecific T-cell engagers (BiTEs) stimulate T lymphocytes proximate to tumor cells, inducing T-cell stimulation and tumor killing. Blinatumomab, an anti CD3-CD19, was the first to be approved with overall response rates of up to 80% in refractory B-cell Acute Lymphoblastic Leukemia (B-ALL). To overcome resistance and to develop next-generation BiTEs, we need to build on blinatumomab's success and better understand BiTEs mode of action and interaction with the tumor microenvironment (TME). Here, we apply advanced multiomics to examine blinatumomab's activation signatures and the sustained dynamics in the tumor and bone marrow (BM) immune TME. Methods Physically interacting Cells sequencing (PIC-seq) is an advanced multiomics technology deciphering the crosstalk between the cellular components of an immunological synapse (Cohen et al., 2022; Giladi et al., 2020). To assess Immediate activation signatures, we applied PIC-seq on a model of B-ALL cell lines (RS4;11, NALM-6) and lymphocytes obtained from healthy subjects, activated by blinatumomab, compared to no-treatment and activation with anti CD3-CD28 antibodies. To examine the Sustained effects on the immune TME, we performed a longitudinal single-cell RNA sequencing of the bone BM of adult B-ALL patients, before and after treatment with blinatumomab in the Division of Hematology in the Tel Aviv Sourasky Medical Center in 2021-22. Results Immediate activation Applying PIC-seq on n=16,543 CD3 and CD19+ cells, we identified the distinct gene expression of ‘blinatumomab-activated lymphocytes’ (Figure 1). Blinatumomab induced cellular synapses composed of specific T lymphocytes subsets along the activation continuum, namely: effector T cells (CCL5, GNLY, NKG7), early IFN-G activation (IRF1, GBP5), activated cytotoxic (Xcl1-2, IFN-G) and proliferating T cells (CD69, CCND2) . ‘Blinatumomab-activated lymphocytes’ were characterized by a unique activation signature: upregulation of cytotoxicity (Xcl1, IFN-G, GNLY), co-stimulation and B-T cells crosstalk (CD40, CD27, TNFRSF18), immune recruitment (CXCL10, CCL4) and antigen-presentation (TNFSF14, ITGB2) pathways. Late synapses also expressed immunoregulatory molecules (TNFAIP8L2). This signature differed from classical anti CD3-CD28 induced activation and is independent of the donor and the target-cell identity. The malignant cells' response varied: RS4;11 cells manifested cellular senescence, while NALM-6 upregulated INFG-induced apoptotic pathways, suggesting indirect killing in the mechanism of action of BiTEs. Data on the introduction of primary B-ALL patients' cells will be presented at the ASH. Sustained effects We profiled &amp;gt;11,000 cells from three patients: Patient 1, 31-year-old (y/o) female, primary refractory B-ALL (50% BM blasts), attaining transient MRD negativity. Patient 2, 71-y/o male, primary refractory Ph+ B-ALL (74% BM blasts) achieving reduction in MRD following first cycle. Patient 3, 71 y/o, Ph+ B-ALL, treated as consolidation therapy, achieving MRD negativity. Blinatumomab induced a dramatic perturbation in the lymphocytic and myeloid compartments of the BM and was highly patient-specific ( Figure 2). The BM lymphocytic compartment prior to initiation of blinatumomab in molecular remission (patient 3) was characterized by active T and Natural Killer cell states, compared to an abundancy of naïve lymphocytes in active disease (patients 1 and 2). There were no signs of T-cell exhaustion pre or post treatment in all patients. Post-treatment, CD8 T-Central Memory cells proliferated in all patients. Patients treated for active disease (patients 2 and 3), had an expansion of the Tregs population post-treatment. In the myeloid compartment, patients with active disease had more non-classical monocytes, known to correlate with poor prognosis. These were replaced by classical monocytes following treatment, in addition to the emergence of a macrophage-precursor population. Data on the BM and peripheral blood dynamics of an additional six patients will be presented at the ASH. Conclusions We present an advanced single cell dissection of blinatumomab-induced target-effector interaction, providing novel insights into the mechanism of action and TME dynamics to guide patient selection and next generation BiTEs. A larger patients' cohort and introduction of patients' cells to the PIC-seq in vitro model will be presented at the ASH.

BM-MSCs display altered gene expression profiles in B-cell acute lymphoblastic leukemia niches and exert pro-proliferative effects via overexpression of IFI6

BackgroundThe tumor microenvironment (TME) is a supportive environment responsible for promoting the growth and proliferation of tumor cells. Current studies have revealed that the bone marrow mesenchymal stem cells (BM-MSCs), a type of crucial stromal cells in the TME, can promote the malignant progression of tumors. However, in the adult B-cell acute lymphoblastic leukemia (B-ALL) microenvironment, it is still uncertain what changes in BM-MSCs are induced by leukemia cells.MethodsIn this study, we mimicked the leukemia microenvironment by constructing a BM-MSC–leukemia cell co-culture system. In vitro cell experiments, in vivo mouse model experiments, lentiviral transfection and transcriptome sequencing analysis were used to investigate the possible change of BM-MSCs in the leukemia niche and the potential factors in BM-MSCs that promote the progression of leukemia.ResultsIn the leukemia niche, the leukemia cells reduced the MSCs' capacity to differentiate towards adipogenic and osteogenic subtypes, which also promoted the senescence and cell cycle arrest of the MSCs. Meanwhile, compared to the mono-cultured MSCs, the gene expression profiles of MSCs in the leukemia niche changed significantly. These differential genes were enriched for cell cycle, cell differentiation, DNA replication, as well as some tumor-promoting biofunctions including protein phosphorylation, cell migration and angiogenesis. Further, interferon alpha-inducible protein 6 (IFI6), as a gene activated by interferon, was highly expressed in leukemia niche MSCs. The leukemia cell multiplication was facilitated evidently by IFI6 both in vitro and in vivo. Mechanistically, IFI6 might promote leukemia cell proliferation by stimulating SDF-1/CXCR4 axis, which leads to the initiation of downstream ERK signaling pathway. As suggested by further RNA sequencing analysis, the high IFI6 level in MSCs somewhat influenced the gene expression profile and biological functions of leukemia cells.ConclusionsBM-MSCs in the leukemia niche have varying degrees of changes in biological characteristics and gene expression profiles. Overexpression of IFI6 in BM-MSCs could be a key factor in promoting the proliferation of B-ALL cells, and this effect might be exerted through the SDF-1/CXCR4/ERK signal stimulation. Targeting IFI6 or related signaling pathways might be an important measure to reduce the leukemia cell proliferation.