B-cell Lymphoblastic Leukemia Research Articles

Genetic and clinical characteristics of acute B-cell lymphoblastic leukemia with MEF2D fusions and report of two novel MEF2D rearrangements.

The MEF2D rearrangement is a recurrent chromosomal abnormality detected in approximately 2.4-5.3% of patients with acute B-cell lymphoblastic leukemia (B-ALL). Currently, MEF2D-rearranged B-ALL is not classified as an independent subtype in the WHO classification. Consequently, the clinical significance of MEF2D rearrangement in B-ALL remains largely unexplored. In this study, we retrospectively screened 260 B-ALL patients with RNA sequencing data collected between November 2018 and December 2022. Among these, 10 patients were identified with MEF2D rearrangements (4 with MEF2D::HNRNPUL1, 3 with MEF2D::BCL9, 1 with MEF2D::ARID1B, 1 with MEF2D::DAZAP1 and 1 with MEF2D::HNRNPM). Notably, HNRNPM and ARID1B are reported as MEF2D fusion partners for the first time. The patient with the MEF2D::HNRNPM fusion was resistant to chemotherapy and chimeric antigen receptor T-cell therapy and relapsed early after allogenic stem cell transplantation. The patient with MEF2D::ARID1B experienced early extramedullary relapse after diagnosis. All 10 patients achieved complete remission after induction chemotherapy. However, 9/10 (90%) of whom experienced relapse. Three of the 9 patients relapsed with aberrant expression of myeloid antigens. The median overall survival of these patients was only 11 months. This small cohort showed a high incidence of early relapse and short survival in patients with MEF2D rearrangements.

Combination of venetoclax and azacitidine in relapsed/refractory acute B-cell lymphoblastic leukemia: a case series from a single center

ABSTRACT Objectives Relapsed/refractory acute B-cell lymphoblastic leukemia (R/R B-ALL) often responds poorly to induction chemotherapy. However, recent research has shown a novel and effective drug treatment for R/R B-ALL. Methods A total of eight patients with R/R B-ALL were enrolled in the study from November 2021 to August 2022. All patients received chemotherapy based on a combination regimen of venetoclax and azacitidine. The regimen was as follows venetoclax 100 mg d1, 200 mg d2, 400 mg d3–14, azacitidine 75 mg/m2 d1–7. Results Five of eight patients achieved very deep and complete remission (CR) with minimal residual disease (MRD) less than 0.1%. One patient achieved partial remission. Two patients did not achieve remission. There were no serious adverse events and all patients were well tolerated. Three patients were eligible for consolidation chemotherapy and were bridged to CAR-T therapy. Conclusions The combined regimen of venetoclax and azacitidine may be beneficial for patients with R/R B-ALL.

Tisagenlecleucel for Treatment of Refractory or Relapsed B-cell Acute Lymphoblastic Leukemia (R/R B-All): A Systematic Review of Cost-Effectiveness Analysis

Tisagenlecleucel is a new immunological therapy in refractory or relapsed B-cell lymphoblastic leukemia with high expense. Objective: To assess the quality as well as analyze characteristics and results of cost-effectiveness analysis (CEA) of tisagenlecleucel immunological therapy in children with R/R B-ALL. Method: To analyze systematic review of articles published during the period of 2017-2023 in Pubmed, ScienceDirect, GoogleScholar, Cochrane databases. Result: 10 selected studies were carried out in 8 nations with different cost units and discount rates. Compared therapies were standard therapy of each country included Blinatumomab, Clo-C, Clo-M, FLA-IDA, FLAG-IDA. Of 10 studies, 70% was considered cost-effectiveness, 20% non-conclusion and only 10% not cost-effectiveness. Conclusion: Tisagenlecleucel’s cost is the highest among compared therapies but it can be cost-effective in a nation with WTP threshold of $100.000-$150.000.
 Keywords: Systematic review, cost-effective, tisagenlecleucel, CAR-T, acute lymphoblastic leukemia.
 

Histopathologic evidence of chimeric antigen receptor T-cell therapy in lesions of B-cell lymphoblastic leukemia cutis.

Histopathologic evidence of chimeric antigen receptor T-cell therapy in lesions of B-cell lymphoblastic leukemia cutis.

Clinical Features and Prognosis of Acute T-cell Lymphoblastic Leukemia in Children--Multi-Center Data Analysis in Fujian

To evaluate the efficacy of acute T-cell lymphoblastic leukemia (T-ALL) in children and explore the prognostic risk factors. The clinical data of 127 newly diagnosed children with T-ALL admitted to five hospitals in Fujian province from April 2011 to December 2020 were retrospectively analyzed, and compared with children with newly diagnosed acute precursor B-cell lymphoblastic leukemia (B-ALL) in the same period. Kaplan-Meier analysis was used to evaluate the overall survival (OS) and event-free survival (EFS), and COX proportional hazard regression model was used to evaluate the prognostic factors. Among 116 children with T-ALL who received standard treatment, 78 cases received the Chinese Childhood Leukemia Collaborative Group (CCLG)-ALL 2008 protocol (CCLG-ALL 2008 group), and 38 cases received the China Childhood Cancer Collaborative Group (CCCG)-ALL 2015 protocol (CCCG-ALL 2015 group). The efficacy and serious adverse event (SAE) incidence of the two groups were compared. Proportion of male, age≥10 years old, white blood cell count (WBC)≥50×109/L, central nervous system leukemia, minimal residual disease (MRD)≥1% during induction therapy, and MRD≥0.01% at the end of induction in T-ALL children were significantly higher than those in B-ALL children (P <0.05). The expected 10-year EFS and OS of T-ALL were 59.7% and 66.0%, respectively, which were significantly lower than those of B-ALL (P <0.001). COX analysis showed that WBC≥100×109/L at initial diagnosis and failure to achieve complete remission (CR) after induction were independent risk factors for poor prognosis. Compared with CCLG-ALL 2008 group, CCCG-ALL 2015 group had lower incidence of infection-related SAE (15.8% vs 34.6%, P =0.042), but higher EFS and OS (73.9% vs 57.2%, P EFS=0.090; 86.5% vs 62.3%, P OS=0.023). The prognosis of children with T-ALL is worse than children with B-ALL. WBC≥100×109 /L at initial diagnosis and non-CR after induction (especially mediastinal mass has not disappeared) are the risk factors for poor prognosis. CCCG-ALL 2015 regimen may reduce infection-related SAE and improve efficacy.

An Anti-CD7 Antibody-Drug Conjugate Target Showing Potent Antitumor Activity for T-Lymphoblastic Leukemia (T-ALL).

Acute T-lymphoblastic leukemia (T-ALL) is a type of leukemia that can occur in both pediatric and adult populations. Compared to acute B-cell lymphoblastic leukemia (B-ALL), patients with T-cell T-ALL have a poorer therapeutic efficacy. In this study, a novel anti-CD7 antibody-drug conjugate (ADC, J87-Dxd) was successfully generated and used for T-ALL treatment. Firstly, to obtain anti-CD7 mAbs, we expressed and purified the CD7 protein extracellular domain. Utilizing hybridoma technology, we obtained three anti-CD7 mAbs (J87, G73 and A15) with a high affinity for CD7. Both the results of immunofluorescence and Biacore assay indicated that J87 (KD = 1.54 × 10-10 M) had the highest affinity among the three anti-CD7 mAbs. In addition, an internalization assay showed the internalization level of J87 to be higher than that of the other two mAbs. Next, we successfully generated the anti-CD7 ADC (J87-Dxd) by conjugating DXd to J87 via a cleavable maleimide-GGFG peptide linker. J87-Dxd also possessed the ability to recognize and bind CD7. Using J87-Dxd to treat T-ALL cells (Jurkat and CCRF-CEM), we observed that J87-Dxd bound to CD7 was internalized into T-ALL cells. Moreover, J87-Dxd treatment significantly induced the apoptosis of Jurkat and CCRF-CEM cells. The IC50 (half-maximal inhibitory concentration) value of J87-Dxd against CCRF-CEM obtained by CCK-8 assay was 6.3 nM. Finally, to assess the antitumor efficacy of a J87-Dxd in vivo, we established T-ALL mouse models and treated mice with J87-Dxd or J87. The results showed that on day 24 after tumor inoculation, all mice treated with J87 or PBS died, whereas the survival rate of mice treated with J87-Dxd was 80%. H&E staining showed no significant organic changes in the heart, liver, spleen, lungs and kidneys of all mice. In summary, we demonstrated that the novel anti-CD7 ADC (J87-Dxd) had a potent and selective effect against CD7-expressing T-All cells both in vitro and in vivo, and could thus be expected to be further developed as a new drug for the treatment of T-ALL or other CD7-expression tumors.

Impact of inotuzumab ozogamicin on outcome in relapsed or refractory acute B-cell lymphoblastic leukemia patients prior to allogeneic hematopoietic stem cell transplantation and risk of sinusoidal obstruction syndrome/venous occlusive disease.

We evaluated 58 patients with relapsed or refractory (r/r) acute B-lymphoblastic leukemia (B-ALL; median age 42.5 years; range, 16-69 years), treated with inotuzumab ozogamicin (INO) between 2016-2022 and who received an allogeneic hematopoietic stem cell transplantation (allo-HCT) consecutively. Forty-seven (81%) of the 58 patients were heavily pretreated receiving intensive chemotherapy +/- tyrosine kinase inhibitor, blinatumomab in 24 (41%) and allo-HCT at first-line in 11 (19%) patients. Complete remission rate prior to allo-HCT was 84%. Median follow-up was 30.5 months and median overall survival (OS) measured from start of INO was 11.2 months. One- and 2-year OS rates were 50% (95% confidence interval [CI]: 38.4-56.1) and 36.7% (95% CI: 25.5-52.9), respectively. Sinusoidal obstruction syndrome/venous occlusive disease (SOS/ VOD) after allo-HCT occurred in 17 (29%) patients. Of those, nine (53%) patients died due to SOS/VOD and multi-organ failure. Two had received >2 INO cycles (3 cycles, 5 cycles, N=1, each), all others ≤2 INO cycles prior to allo-HCT. Logistic regression analysis revealed conditioning with double alkylators (P=0.038) and allo-HCT during first-line therapy (P=0.050) as significant risk factors for SOS/VOD and in trend allo-HCT ≤60 days from last INO application (P=0.07), whereas number of INO cycles before allo-HCT and time between last INO application and allo-HCT were not significant. Relapse/progressive disease occurred in 20 (34%) patients. Of those, five (25%) patients are still alive, whereas 15 succumbed of their disease. Treatment with INO seems to be an effective approach with successful bridge-to-transplant. However, risk of SOS/VOD is high, necessitating continuous monitoring and recognition of SOS/VOD risk factors.

A Multicenter Study of CAR-T Cell Therapy for Relapse of B-ALL Post Allogeneic Stem Cell Transplantation

BACKGROUND: Patients with acute B-cell lymphoblastic leukemia (B-ALL) relapsed after allogeneic stem cell transplantation (allo-HSCT) have very poor prognosis. Chimeric antigen receptor T (CAR-T) cells targeting CD19 have been developed as one of the effective immunotherapies for relapsed/refractory B-ALL. The safety and efficacy of CAR-T cells in patients relapsed after allo-HSCT remain unclear. METHODS: This study analyzed 60 B-ALL patients relapsed after allo-HSCT treated with CAR-T cells between October 2015 and February 2022 from four Chinese centers. Their pre-treatment patient characteristics, treatment regimens, efficacy, adverse effects, and follow-up data were comprehensively analyzed. RESULTS: One patient refused efficacy evaluation. 7 patients died before day 28 after CAR-T infusion. A total of 52 were assessed for efficacy within 28 days after CAR-T infusion.76.92% (40/52) patients achieved complete remission (CR) at Day 28 after CAR-T infusion, including 38 patients who achieved MRD-negative CR. 4 of the 40 patients relapsed at a median follow-up date of 12.1 months. The 1-year OS and EFS of all patients were 52.8% ± 7.0% and 51.5% ± 7.0%, respectively, and the 2-year OS and EFS were 40.1% ± 8.6% and 45.1% ± 8.6%, respectively. Multifactorial analysis showed that patients with severe CRS had worse OS and EFS, and other factors including age, gender, site of CAR-T tumor involvement, type of previous transplantation, previous transplantation type, CAR-T product and CRS grade, etc., did not affect the long-term survival of patients. The incidence of CRS was 80.00%, the incidence of grade ≥3 CRS was 20.83%, and the median time of CRS was 2 days after CAR-T cell infusion (range: 0-34 days). 3 patients (5.00%) died due to multiorgan failure caused by severe CRS, and the rest of the patients' CRS was controlled, and the grade of CRS was related to the proportion of blast cells in the bone marrow prior to CAR-T cell infusion., independent of the type of transplantation and the source of CAR-T cells. The incidence of ICANS was 5.00%. The incidence of aGvHD was 30.00%, and patients who had received prior haploidentical allogeneic HSCT were significantly more likely to develop aGvHD after CAR-T cell infusion than those who had received prior matched allogeneic HSCT. The occurrence of aGvHD after CAR-T treatment was not associated with the occurrence of CRS (p = 1), the presence of aGvHD after prior transplantation (p = 0.3484), the presence of cGvHD after prior transplantation (p = 0.3167), the presence of cGvHD at the time of CAR-T infusion (p = 0.5136), and the presence of prior donor lymphocyte infusion (p = 0.7404), and whether CAR-T cells were from autologous or donor (p = 0.4819). CONCLUSIONS: CAR-T cells are safe and effective in treating B-ALL patients with post-transplant relapse, and donor-derived CAR-T cells do not exacerbate CRS with aGVHD, and there is a high incidence of aGVHD after CAR-T therapy in patients with HLA-haplotype-matched transplantation.

Efficacy and Safety of the Second CAR-T Therapy in Patients with Refractory/Relapsed Acute B-Cell Lymphoblastic Leukemia

Background: Chimeric antigen receptor T (CAR-T) cells therapy has shown significant efficacy in relapsed or refractory B-cell acute lymphoblastic leukemia (R/R B-ALL), but a substantial proportion of patients still relapse after a period of remission. The efficacy of a second CAR-T cell infusion is uncertain. The aim of this study was to explore the efficacy and safety of the second CAR-T therapy in R/R B-ALL patients. Methods: Between August 2018 and October 2022, 35 patients with R/R B-ALL successfully received the second CAR-T treatment. Among them, 18 patients received single CD19 or CD22 CAR-T therapy, 14 patients received tandem CD19/CD22 CAR-T therapy, and 3 patients received sequential CD19 and CD22 CAR-T therapy. Results: The complete remission (CR) rates were 55.6% (10/18) in patients who received CD19 or CD22 CAR-T therapy, 85.7% (12/14) in patients who received tandem CD19/CD22 CAR-T therapy, and 33.3% (1/3) in patients who received sequential CD19 and CD22 CAR-T therapy (tandem CD19/CD22 vs. others, P=0.045). Tandem CD19/CD22 CAR-T therapy remained one of the significant favorable factors in multivariate logistic regression analysis of CR rate in all patients (hazard ratio, 0.128; 95% CI, 0.017-0.974). A total of 5 patients with severe cytokine release syndrome (Grade ≥ 3) were observed, including 2 patients in the single CD19 CAR-T group, 2 patients in the tandem CD19/CD22 CAR-T group, and 1 patient in the sequential CD19 and CD22 CAR-T group. Of the 23 patients who achieved CR, 4 patients bridged to allogeneic hematopoietic stem cell transplantation (allo-HSCT) and 3 patients received decitabine (DAC) consolidation.With the median follow-up of 25.5 months (range, 1.1 to 33.5), the 2-year overall survival, leukemia-free survival (LFS) and cumulative incidence of relapse rates were 23.7%, 30.5% and 69.5%, respectively. Multivariate Cox regression analyses showed that a better LFS related to the absence of high-risk cytogenetics and genetic characteristics, DAC combination with fludarabine and cyclophosphamide lymphodepletion regimen, and bridging allo-HSCT or DAC consolidation. Conclusions: Our study showed that the second infusion of tandem CD19/CD22 CAR-T therapy obtains a better response than other infusion strategies. Bridging allo-HSCT or DAC consolidation had a significant survival benefit in patients with CR after the second CAR-T therapy.

Clinical analysis of long-term survival and influencing factors of chimeric antigen receptor T-cell therapy in relapsed/refractory acute B-cell lymphoblastic leukemia

Objective: To analyze the survival and influencing factors of chimeric antigen receptor (CAR) T-cell therapy in relapsed/refractory acute B-cell lymphoblastic leukemia (R/R B-ALL) . Methods: Clinical information of patients who received CAR-T-cell therapy and achieved complete remission of R/R B-ALL between May 2015 and June 2018 at the Shaanxi Provincial People's Hospital was obtained. Kaplan-Meier analysis was used to evaluate the overall survival (OS) and leukemia-free survival (LFS) times of patients, and Cox regression analysis was performed to analyze the prognostic factors that affect patient survival after CAR-T therapy. Results: Among the 38 patients with R/R B-ALL, 21 were men, with a median age of 25 (6-59) years and a median OS time of 18 (95% CI 3-33) months. Multivariate Cox regression analysis showed that positive MLL-AF4 fusion gene expression was an independent risk factor for OS and LFS (OS: HR=4.888, 95% CI 1.375-17.374, P=0.014; LFS: HR=6.683, 95% CI 1.815-24.608, P=0.004). Maintenance therapy was a protective factor for OS and LFS (OS: HR=0.153, 95% CI 0.054-0.432, P<0.001; LFS: HR=0.138, 95% CI 0.050-0.382, P<0.001). In patients with MRD negative conversion, LFS benefit (HR=0.209, 95% CI 0.055-0.797, P=0.022) and OS difference was statistically insignificant (P=0.111). Moreover, patients with high tumor burden were risk factors for OS and LFS at the level of 0.1 (OS: HR=2.662, 95% CI 0.987-7.184, P=0.053; LFS: HR=2.452, 95% CI 0.949-6.339, P=0.064) . Conclusion: High tumor burden and high-risk genetics may affect the long-term survival rate of patients with R/R B-ALL receiving CAR-T, and lenalidomide-based maintenance therapy may improve their prognosis.

Bone and joint disease – Not always a rheumatological diagnosis

Abstract A 17-year-old female presented with a 7-day history of joint pains involving the bilateral knee, ankle and small joints of the hands and feet symmetrically, associated with bilateral knee joint swelling and early morning stiffness and bilateral red eyes. General examination was normal except for pallor. Musculoskeletal system examination revealed bilateral swollen and tender knee joints with restriction of movement along with tenderness in the bilateral shoulder, elbow, ankle joints and spine from T3 to T7 thoracic vertebral levels. Examination of other systems was normal. Investigations showed anaemia, elevated urea and creatinine. Skeletal survey showed multiple lytic lesions. Positron emission tomography revealed multiple punched-out lytic lesions in skull bones, scapulae, sternum, clavicles, ribs on both sides, vertebrae at multiple levels and in pelvic girdle bones. Few lesions showed mild 18fluorodeoxyglucose (18FDG) uptake, metaphyseal moth-eaten lysis in long bones with mild FDG uptake. Bone marrow biopsy and immunohistochemistry confirmed the diagnosis of acute B-cell lymphoblastic leukaemia. The terminology is according to 2016 revision of WHO classification of myeloid neoplasms and acute leukemia.

Endothelial-derived small extracellular vesicles support B-cell acute lymphoblastic leukemia development.

The bone marrow niche plays an important role in leukemia development. However, the contributions of different niche components to leukemia development and their underlying mechanisms remain largely unclear. Cre/LoxP-based conditional knockout technology was used to delete VPS33B or ANGPTL2 gene in niche cells. Murine B-ALL model was established by overexpressing the N-Myc oncogene in hematopoietic stem progenitor cells. The frequency of leukemia cells and immunophenotypic B220+ CD43+ LICs was detected by flow cytometry. SEVs was isolated by sequential centrifugation and mass spectrometry was performed to analyze the different components of SEVs. Immunoprecipitation and western blot were used to measure the interaction of VPS33B and ANGPTL2. Here, we showed that specific knockout of vascular protein sorting 33b (Vps33b) in endothelial cells (ECs), but not megakaryocytes or mesenchymal stem cells, resulted in a significant decrease in the secretion of small extracellular vesicles (SEVs) and a delay in the development of B-cell lymphoblastic leukemia (B-ALL). Vps33b knockdown endothelial cells contained much lower levels of SEVs that contained angiopoietin-like protein 2 (ANGPTL2) than the control cells. Importantly, conditional knockout of Angptl2 in ECs significantly delayed B-ALL progression. Moreover, C-terminal region of ANGPTL2 (aa247-471) could directly interact with Sec1-like domain 1 of VPS33B (aa1-aa146). We further demonstrated that the point mutations R399H and G402S in ANGPTL2 led to a dramatic decrease in the secretion of ANGPTL2-SEVs. We also showed that wild-type ANGPTL2-containing SEVs, but not mutant ANGPTL2-containing SEVs, significantly enhanced B-ALL development. In summary, our findings indicate that the secretion of ANGPTL2-containing SEVs in ECs sustains the leukemogenic activities of B-ALL cells, which is fine-tuned by the direct interaction of VPS33B and ANGPTL2. These findings reveal that niche-specific SEVs play an important role in B-ALL development.

The off-target effects of AID in carcinogenesis.

Activation-induced cytidine deaminase (AID) plays a crucial role in promoting B cell diversification through somatic hypermutation (SHM) and class switch recombination (CSR). While AID is primarily associated with the physiological function of humoral immune response, it has also been linked to the initiation and progression of lymphomas. Abnormalities in AID have been shown to disrupt gene networks and signaling pathways in both B-cell and T-cell lineage lymphoblastic leukemia, although the full extent of its role in carcinogenesis remains unclear. This review proposes an alternative role for AID and explores its off-target effects in regulating tumorigenesis. In this review, we first provide an overview of the physiological function of AID and its regulation. AID plays a crucial role in promoting B cell diversification through SHM and CSR. We then discuss the off-target effects of AID, which includes inducing mutations of non-Igs, epigenetic modification, and the alternative role as a cofactor. We also explore the networks that keep AID in line. Furthermore, we summarize the off-target effects of AID in autoimmune diseases and hematological neoplasms. Finally, we assess the off-target effects of AID in solid tumors. The primary focus of this review is to understand how and when AID targets specific gene loci and how this affects carcinogenesis. Overall, this review aims to provide a comprehensive understanding of the physiological and off-target effects of AID, which will contribute to the development of novel therapeutic strategies for autoimmune diseases, hematological neoplasms, and solid tumors.

Pegylated-Asparaginase Induced Severe Hypertriglyceridemia in an Adult with Acute B-cell Lymphoblastic Leukemia

Pegylated-Asparaginase Induced Severe Hypertriglyceridemia in an Adult with Acute B-cell Lymphoblastic Leukemia

THE ROLE OF CLINICAL-HEMATOLOGICAL AND CYTOGENETIC CHARACTERISTICS IN THE PROGRAM THERAPY OF B-CELL LEUKEMIA IN CHILDREN IN THE REPUBLIC OF KAZAKHSTAN

Relevance: The study of immunological and molecular genetic characteristics of leukemia in children and the influence of biological features of the tumor population of acute B-cell lymphoblastic leukemia (B-ALL) on the effectiveness of therapy is particularly relevant for the Republic of Kazakhstan.&#x0D; The study aimed to evaluate the effectiveness of modern program chemotherapy in children depending on the biological characteristics of B-cell leukemias.&#x0D; Methods: The study analyzed the data of 154 children aged six months to 15 years with primary B-ALL on inpatient treatment at the Scientific Center of Pediatrics and Pediatric Surgery JSC (Almaty, the Republic of Kazakhstan) in 2016-2018. When determining events, we were guided by the criteria of the protocols of the ALL-BFM group.&#x0D; Results: The age groups most exposed to B-ALL were 3-7 years old (43.5%), reflecting the so-called infant peak. In the clinical picture of this type of ALL, intoxication syndrome accompanying the period of manifestation was present in 75.3% of patients. The clinical polymorphism of the debut period determined the most diverse list of diagnoses of “masks.” Damage to organs and systems, in the form of liver failure, was detected in 41 (26.6%) children, with the development of respiratory failure in 12 (7.8%), cardiovascular failure in 5 patients (3.2%), acute kidney injury in 3 (1.9%), CNS damage in 5 (3.2%) patients. With B-ALL, the distribution of immunological variants was determined as follows: B1 – 9 (5.8%), B2 – 123 (79.8%), B3 – 18 (11,7%), B4 – 4 (2,6%) and leukemia of B-cell lymphoma was noted in one (0.6%) patient. From the group of quantitative anomalies, hyperploidy was detected in 12 (7.8%) cases. Among qualitative anomalies, t(12;21) (p13;q22) was determined in 6 (3.9%) patients and was a favorable prognostic factor (remission was recorded). Trisomy of chromosome 21 with Down syndrome in 3 (1.9%) patients with combined anomalies (isochromosome 7, trisomy 4, 6, 15, 17, translocation t(9; 22)(q34;q11) was detected in 1.3%. Translocations t(1;19)(q23;p13.3) in 5.8% and del 9-chromosome defect in 3.2% of cases.&#x0D; Conclusion: The response to therapy and long-term prognosis are largely determined by biological factors such as cytogenetic features of the tumor, sensitivity to prednisone, as well as the degree of aggressiveness, which manifests itself in the form of pronounced symptoms of lymphoproliferation and hyperleukocytosis. The research has shown the high efficiency of modern ALL-BFM program therapy in children.

THE ROLE OF CLINICAL-HEMATOLOGICAL AND CYTOGENETIC CHARACTERISTICS IN THE PROGRAM THERAPY OF B-CELL LEUKEMIA IN CHILDREN IN THE REPUBLIC OF KAZAKHSTAN

Relevance: The study of immunological and molecular genetic characteristics of leukemia in children and the influence of biological features of the tumor population of acute B-cell lymphoblastic leukemia (B-ALL) on the effectiveness of therapy is particularly relevant for the Republic of Kazakhstan.&#x0D; The study aimed to evaluate the effectiveness of modern program chemotherapy in children depending on the biological characteristics of B-cell leukemias.&#x0D; Methods: The study analyzed the data of 154 children aged six months to 15 years with primary B-ALL on inpatient treatment at the Scientific Center of Pediatrics and Pediatric Surgery JSC (Almaty, the Republic of Kazakhstan) in 2016-2018. When determining events, we were guided by the criteria of the protocols of the ALL-BFM group.&#x0D; Results: The age groups most exposed to B-ALL were 3-7 years old (43.5%), reflecting the so-called infant peak. In the clinical picture of this type of ALL, intoxication syndrome accompanying the period of manifestation was present in 75.3% of patients. The clinical polymorphism of the debut period determined the most diverse list of diagnoses of “masks.” Damage to organs and systems, in the form of liver failure, was detected in 41 (26.6%) children, with the development of respiratory failure in 12 (7.8%), cardiovascular failure in 5 patients (3.2%), acute kidney injury in 3 (1.9%), CNS damage in 5 (3.2%) patients. With B-ALL, the distribution of immunological variants was determined as follows: B1 – 9 (5.8%), B2 – 123 (79.8%), B3 – 18 (11,7%), B4 – 4 (2,6%) and leukemia of B-cell lymphoma was noted in one (0.6%) patient. From the group of quantitative anomalies, hyperploidy was detected in 12 (7.8%) cases. Among qualitative anomalies, t(12;21) (p13;q22) was determined in 6 (3.9%) patients and was a favorable prognostic factor (remission was recorded). Trisomy of chromosome 21 with Down syndrome in 3 (1.9%) patients with combined anomalies (isochromosome 7, trisomy 4, 6, 15, 17, translocation t(9; 22)(q34;q11) was detected in 1.3%. Translocations t(1;19)(q23;p13.3) in 5.8% and del 9-chromosome defect in 3.2% of cases.&#x0D; Conclusion: The response to therapy and long-term prognosis are largely determined by biological factors such as cytogenetic features of the tumor, sensitivity to prednisone, as well as the degree of aggressiveness, which manifests itself in the form of pronounced symptoms of lymphoproliferation and hyperleukocytosis. The research has shown the high efficiency of modern ALL-BFM program therapy in children.

Which one is better for refractory/relapsed acute B-cell lymphoblastic leukemia: Single-target (CD19) or dual-target (tandem or sequential CD19/CD22) CAR T-cell therapy?

CD19 chimeric antigen receptor (CAR) T-cell therapy has shown great success against B-cell acute lymphoblastic leukemia (B-ALL). Tandem and sequential CD19/CD22 dual-target CAR T-cell therapies have been developed to reduce the possibility of CD19-negative relapse; however, the superior strategy is still uncertain. This study screened 219 patients with relapsed/refractory B-ALL who were enrolled in clinical trials of either CD19 (NCT03919240) or CD19/CD22 CAR T-cell therapy (NCT03614858). The complete remission (CR) rates in the single CD19, tandem CD19/CD22, and sequential CD19/CD22 groups were 83.0% (122/147), 98.0% (50/51), and 95.2% (20/21), respectively (single CD19 vs. tandem CD19/CD22, P = 0.006). Patients with high-risk factors achieved a higher rate of CR in the tandem CD19/CD22 group than in the single CD19 group (100.0% vs. 82.4%, P = 0.017). Tandem CD19/CD22 CAR T-cell therapy was one of the significant favorable factors in the multivariate analysis of the CR rate. The incidence of adverse events was similar among the three groups. Multivariable analysis in CR patients showed that a low frequency of relapse, a low tumor burden, minimal residual disease-negative CR and bridging to transplantation were independently associated with better leukemia-free survival. Our findings suggested that tandem CD19/CD22 CAR T-cell therapy obtains a better response than CD19 CAR T-cell therapy and a similar response to sequential CD19/CD22 CAR T-cell therapy.

Abstract LB077: Analysis of indel and structural variant error profiles in deep next generation sequencing data

Abstract Background: Accurate detection of low frequency mutations is of critical importance in the study of genetic heterogeneity, such as on the detection of minimal residual diseases for leukemias. Our prior work has resulted in successful error suppression for substitutions (10−4-10−5). However, the error profiles of indels and structural variants (SVs) remain elusive. Results: In this work, we generated ultra-deep sequencing data using our previously established dilution models (COLO829) on known somatic indels (n=23) and SVs (n=17). We discovered that the error rate of indels (10−6) and SVs (&amp;lt;2 × 10−7) are 100- to &amp;gt;1000-fold lower than that of SNVs. This finding was fully recapitulated in our analysis of 347 indels and 1248 SVs discovered from a relapsed B-ALL cohort of 103 patients, although homopolymer indels can have high error rates (&amp;gt;1%). We then performed a comprehensive study of homopolymer indels in 361 cancer driver genes by using whole genome data from 1662 healthy donors from the SJLIFE cohort. Our data indicated that the number of repeating units are highly predictive relative to the error rate of homopolymer indels (R2=0.988, p=4.89 × 10−8). Utilizing these insights, we assayed end-of-induction remission samples from 72 B-cell lymphoblastic leukemia patients that relapsed by selecting ~5 somatic clonal SNV/Indel/SV markers, which confirmed that SVs and indels have &amp;gt;10-fold lower error rates than SNVs. Our next generation sequencing (NGS) approach had 44 positive detections (61%) and outperformed the current standard method of clinical flow cytometry (n=37; 51%) for detecting minimal residual disease. The NGS-based method detected 92% of designed markers for samples with MRD&amp;gt;0.3%, and this detection rate dropped to 27% for MRD between 0.1% and 0.01%, indicating the difficulty in recovering mutant molecules when their frequencies are very low. Conclusions: Overall, we established indel and SV error profiles in deep next generation sequencing data enabling superior tumor detection performance at very low burdens, with lower error rates than what is observed for SNVs. Our work will have a significant impact on the clinical diagnosis and monitoring of human cancers and beyond. Citation Format: Ying Shao, Quang Tran, Pandurang Kolekar, Yanling Liu, Andrea McBride, Tyler Jones, Heather Mulder, Lingyun Ji, Benjamin Huang, Soheil Meshinchi, Jeffery Klco, Jinghui Zhang, William Carroll, Mignon Loh, Patrick Brown, John Easton, Xiaotu Ma. Analysis of indel and structural variant error profiles in deep next generation sequencing data [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB077.

Treatment and Response Evaluation Challenges in a Pregnant Woman With B-Cell Lymphoblastic Leukemia and Li-Fraumeni Syndrome

Li-Fraumeni syndrome (LFS) is a cancer predisposing syndrome caused by pathogenic germline TP53 gene mutations with important therapeutic and prognostic implications for many types of cancer. A small proportion of LFS patients develop B-cell lymphoblastic leukemia (B-ALL) in adult years. Standard treatment often proves inadequate, but immunotherapy has provided new treatment options. The current case report presents a pregnant woman with LFS and newly diagnosed B-ALL with hypodiploidy developed after treatment for early-onset breast cancer. We describe the treatment course, treatment-related complications and provide laboratory data crucial for evaluating and modifying treatment for this difficult clinical case. Our findings support the need for close collaboration between clinicians and experts on immunophenotyping. Through our report, we show that immunotherapy is feasible in patients with LFS and B-ALL, despite a poor initial response to induction therapy.

Immune-related adverse events associated with the use of immunotherapy in patients with B-cell lymphoblastic leukemia: A protocol for a systematic review and meta-analysis.

B-cell acute lymphoblastic leukemia (B-ALL) is a neoplasm of immature B-cells that is more prevalent in children. Despite successful remission rates in patients with B-ALL on chemotherapy, the risk of relapse is high. This has paved way for highly active immune and cell therapies to be intensively explored. However, the efficacy and immune-related adverse events (AE) associated with the use of immunotherapies remain elusive. This protocol has been prepared in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols 2015 guidelines. Cochrane Central Register of Controlled Trials, MEDLINE, and Embase electronic databases will be searched to retrieve relevant interventional studies. Two reviewers (BKK and EH) will autonomously search and identify relevant studies using a preset inclusion and exclusion criteria. A predefined data extraction sheet will be used to extract relevant data items. The risk of bias will be assessed by 2 reviewers (BKK and BBN) using the Cochrane risk-of-bias tool for randomized controlled trials and the Downs and Black Checklist for nonrandomized controlled trials. A third reviewer (TMN) will be consulted for any discrepancies. The Grading of Recommendations Assessment Development and Evaluation will be used to assess the strengths of evidence by 2 reviewers (BBK and TMN). The I² and Chi-squared statistical tests will be used to investigate statistical heterogeneity across studies. An I² value of > 50% will be considered substantial heterogeneity and a random-effects model will be used. Data analysis will be performed using Review Manager (RevMan V.5.3) statistical software.