2026-08-15 | Timing of Allogeneic Hematopoietic Cell Transplantation After Inotuzumab Ozogamicin Influences Sinusoidal Obstruction Syndrome and Survival in Relapsed/Refractory B-ALL.
Inotuzumab ozogamicin (InO) is widely used as a bridge to allogeneic hematopoietic cell transplantation (HCT) in patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). However, post-transplant sinusoidal obstruction syndrome (SOS) remains a major complication, and the optimal timing of HCT after InO exposure is not established. To evaluate the impact of InO exposure and timing between InO and HCT on transplant outcomes, with a focus on SOS, non-relapse mortality (NRM), and survival. We conducted a retrospective multicenter observational study across 21 Spanish transplant centers within the Grupo Español de Trasplante Hematopoyético y Terapia Celular (GETH-TC). We included 107 adolescents and adults (≥15 years) with R/R B-ALL who achieved response to InO and proceeded to allogeneic HCT between January 2017 and June 2025. Patients were excluded if refractory to InO. Clinical, treatment, transplant, and outcome data were prospectively collected in a centralized REDCap database. SOS, graft-versus-host disease (GVHD), engraftment, relapse, and survival outcomes were analyzed. Multivariable Cox and Fine-Gray models were used to identify risk factors. The median age was 39 years; 53% were male. Most patients achieved CR prior to HCT, and 74% were MRD-negative. The median interval from last InO dose to HCT was 49 days, and 57% received ≥2 cycles of InO. Conditioning was TBI-based in 54%, and 74% received post-transplant cyclophosphamide. SOS occurred in 34.6% of patients, with 79% classified as severe or very severe. The 120-day cumulative incidence of SOS was 34%, and 27% for severe/very severe SOS. In multivariable analysis, an interval ≤50 days between InO and HCT (HR 3.15), male sex (HR 2.86), and myeloablative TBI-based conditioning (HR 2.47) were independently associated with increased risk of SOS. Higher EASIX scores were also predictive of SOS. Receipt of >2 InO cycles and a short InO-to-HCT interval were associated with increased NRM. SOS was associated with higher NRM (HR 2.78). MRD positivity prior to HCT was associated with higher relapse risk (HR 2.27). At 2 years, OS, LFS, and GRFS were 51%, 42%, and 33%, respectively. A short InO-to-HCT interval (≤50 days), >2 cycles of InO, MRD positivity, and higher EASIX were associated with inferior survival outcomes. In patients with R/R B-ALL undergoing allogeneic HCT after InO, SOS is frequent and clinically significant. A short interval between InO and HCT (≤50 days) and greater InO exposure are independently associated with increased SOS, NRM, and inferior survival. These findings identify potentially modifiable, clinically actionable factors that may improve transplant outcomes.
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2026-08-14 | In vitro and in silico evaluation of the synergistic effect of Cytarabine and Zataria multiflora Boiss extract on pre-B acute lymphoblastic leukemia cells (NALM-6 cell line).
Although cytarabine remains a cornerstone chemotherapeutic agent for Acute lymphoblastic leukemia (ALL), its clinical efficacy is frequently compromised by systemic toxicity and resistance mechanisms, notably telomerase activation via hTERT upregulation. This study investigates the synergistic potential of Zataria multiflora extract (ZME) combined with cytarabine to induce apoptosis in pre-B ALL cells (NALM-6) and explores the underlying molecular mechanisms. In vitro experiments were conducted using the NALM-6 cell line. Cell viability was assessed via Trypan blue exclusion and MTT assays. Apoptosis was quantified using Annexin V/PI flow cytometry. The mRNA expression levels of BAX, BCL2, and hTERT were evaluated by qRT-PCR. Additionally, in silico molecular docking was performed to analyze the interactions between the primary active components of ZME (thymol and carvacrol), cytarabine, and the MDM2 protein. Single-agent treatments (100 µg/mL ZME or 0.5 µM cytarabine) yielded 70-80% cell viability after 48 h. However, the combination therapy significantly enhanced cytotoxicity, inducing 47.54% apoptosis. Gene expression analysis revealed an elevated BAX/BCL2 ratio and a significant downregulation of hTERT, indicating activation of the intrinsic apoptotic pathway and inhibition of telomerase activity. In silico docking demonstrated strong binding affinities between thymol/carvacrol and the MDM2 active site, suggesting a hypothetical disruption of the MDM2-p53 interaction. The combination of ZME and cytarabine synergistically enhances apoptosis in NALM-6 cells by concurrently modulating apoptotic signaling and telomerase-related gene expression. These findings underscore the potential of ZME as a chemosensitizing agent in ALL and provide a rationale for further in vivo validation.
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2026-08-13 | Therapeutic Advances in Adult B-cell Acute Lymphoblastic Leukemia with KMT2A Rearrangements.
B-cell acute lymphoblastic leukemia (ALL) with KMT2A rearrangements (KMT2Ar B-ALL) represents a distinct, high-risk subtype in adults, characterized by aggressive disease biology, high relapse rates, and inferior long-term survival. Conventional intensive chemotherapy, even when consolidated with allogeneic hematopoietic stem cell transplantation (allo-HSCT), yields suboptimal outcomes, underscoring the need for novel therapeutic approaches. In recent years, substantial progress has been made with the introduction of antibody-based immunotherapies, cellular immunotherapies, and small molecular inhibitors, reshaping the treatment landscape for this challenging subgroup. This review provides a comprehensive overview of current and emerging therapeutic strategies for adult patients with KMT2Ar B-ALL. We summarize outcomes associated with pediatric-inspired chemotherapy and allo-HSCT, focus on clinical evidence for antibody-based immunotherapy including blinatumomab and inotuzumab ozogamicin, across frontline, consolidation, and relapsed or refractory settings. Advances in cellular immunotherapy, particularly CD19-directed chimeric antigen receptor T-cell therapy, are discussed, with a focus on unique resistance mechanisms such as antigen loss and lineage switch. In addition, we review the biological rationale, efficacy and emerging resistance mechanisms of menin inhibitors, a promising class of agents specifically targeting the epigenetic dependency of KMT2A-rearranged leukemia. Finally, other molecular approaches, including epigenetic modifiers, apoptosis pathway inhibitors, and signaling pathway inhibitors are discussed. Despite these advances, treatment resistance and disease relapse remain major obstacles. These ongoing challenges highlight the urgent need for multi-center, prospective trials to investigate rational combination strategies to improve outcomes for adults with KMT2Ar B-ALL.
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2026-08-10 | Laboratory Concordance and Prognostic Impact of 10-Color Flow Cytometry and Next-Generation Sequencing-Based Immunoglobulin Gene Assay for Measurable Residual Disease Monitoring in Adult B-Cell Acute Lymphoblastic Leukemia: A Multicenter Study From Thai Acute Leukemia Working Group (TALWG).
Measurable residual disease (MRD) is a key prognostic marker for patient survival. This study evaluated concordance between 10-color flow cytometry and next-generation sequencing (NGS)-based immunoglobulin heavy chain (IGH) gene assays for MRD detection and to assess prognostic significance in adult B-cell acute lymphoblastic leukemia (B-ALL). This multicenter prospective study enrolled 51 patients with newly diagnosed B-ALL. Bone marrow samples were obtained at diagnosis, post-induction (1 month), and post-early consolidation (3 months). Flow cytometry and NGS-IGH were performed at three timepoints to assess MRD B-ALL. Patients were classified as high risk according to white blood cell count and cytogenetic features in 37.3% and 64.7% of patients, respectively. Treatment protocols included pediatric-inspired regimens (41.2%), adult-ALL protocols (52.9%), and low-intensity chemotherapy. All 16 Philadelphia chromosome-positive patients received tyrosine kinase inhibitors. Twenty patients underwent allogeneic hematopoietic cell transplantation (HCT) in first complete remission (CR). Median relapse-free survival (RFS) and overall survival were 19 and 39 months, respectively. MRD negativity at 3 months by either method correlated with significantly superior RFS. Allogeneic HCT also conferred RFS benefit. MRD positive patients without HCT had the worst RFS. Flow cytometry MRD positivity at 3 months independently predicted inferior RFS (HR 3.81; 95% CI 1.01-14.43). The overall concordance between flow cytometry and NGS was 80.7%. MRD positivity at 3 months post-treatment strongly predicted relapse, supporting its use to guide therapeutic modifications of B-ALL. Apart from NGS-based IGH clonality assays, 10-color flow cytometry offers an alternative in resource-limited settings.
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2026-08-10 | Measurable Residual Disease-Dependent Unfavorable Outcomes in Pediatric PAX5-Rearranged B-Acute Lymphoblastic Leukemia.
PAX5-altered acute lymphoblastic leukemia (PAX5-alt ALL) is a recently recognized molecular subtype of B-ALL characterized by a distinct transcriptional signature and frequent PAX5 fusions (PAX5-r). While PAX5-alt ALL has been associated with intermediate outcomes, clinical data specifically investigating pediatric PAX5-r ALL remain limited. We collected and analyzed 159 pediatric cases of PAX5-r ALL treated between 2001-2024 within AIEOP-BFM ALL studies across Italy, Germany and Austria, revealing high-risk clinical features. Comparative analyses of patients consecutively enrolled in the AIEOP-BFM ALL 2017 study (PAX5-r, n=96 vs. non-PAX5-r, n=1948) confirmed higher rates of hyperleukocytosis at diagnosis (22.9% vs. 8%, p<0.001) and enrichment of IKZF1plus profile (14.7% vs. 7.8%, p=0.0015) in PAX5-r patients. No relevant differences in terms of minimal/measurable residual disease (MRD)-based treatment response and risk-group stratification were observed. PAX5-r patients had a 4-year EFS and OS of 72.6±5.7% and 95.4±2.3%, respectively. Four-year EFS were 100%, 63.4±9.7% and 63.3±10% for standard-risk, medium-risk (MR) and high-risk (HR) groups, respectively, indicating that the poor prognostic impact of PAX5-r applies only when end-of-induction MRD is positive (MR/HR). Whole transcriptome sequencing revealed high FLT3 median expression in PAX5-r ALL and high-throughput drug screening of patient-derived xenografts (PDXs) showed marked sensitivity to several FLT3 inhibitors. Gilteritinib showed potent ex vivo cytotoxicity and synergism with dexamethasone in PAX5-r PDX models. Collectively, this study investigated clinical and biological features of pediatric PAX5-r ALL highlighting its MRD-dependent unfavorable prognosis and identifying FLT3 overexpression as a novel, potential therapeutic target.
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