Relapsed Acute Lymphoblastic Leukemia Research Articles

Identifying Candidate Gene Drivers Associated with Relapse in Pediatric T-Cell Acute Lymphoblastic Leukemia Using a Gene Co-Expression Network Approach.

Pediatric T-cell Acute Lymphoblastic Leukemia (T-ALL) relapses are still associated with a dismal outcome, justifying the search for new therapeutic targets and relapse biomarkers. Using single-cell RNA sequencing (scRNAseq) data from three paired samples of pediatric T-ALL at diagnosis and relapse, we first conducted a high-dimensional weighted gene co-expression network analysis (hdWGCNA). This analysis highlighted several gene co-expression networks (GCNs) and identified relapse-associated hub genes, which are considered potential driver genes. Shared relapse-expressed genes were found to be related to antigen presentation (HLA, B2M), cytoskeleton remodeling (TUBB, TUBA1B), translation (ribosomal proteins, EIF1, EEF1B2), immune responses (MIF, EMP3), stress responses (UBC, HSP90AB1/AA1), metabolism (FTH1, NME1/2, ARCL4C), and transcriptional remodeling (NF-κB family genes, FOS-JUN, KLF2, or KLF6). We then utilized sparse partial least squares discriminant analysis to select from a pool of 481 unique leukemic hub genes, which are the genes most discriminant between diagnosis and relapse states (comprising 44, 35, and 31 genes, respectively, for each patient). Applying a Cox regression method to these patient-specific genes, along with transcriptomic and clinical data from the TARGET-ALL AALL0434 cohort, we generated three model gene signatures that efficiently identified relapsed patients within the cohort. Overall, our approach identified new potential relapse-associated genes and proposed three model gene signatures associated with lower survival rates for high-score patients.

A Late Testicular Relapse in an Adult with Acute Lymphoblastic Leukemia, 5 Years after the Diagnosis and 4 Years after Allotransplant-A Rare Case.

Acute lymphoblastic leukemia (ALL) is a malignant disorder of lymphoid progenitor cells that affects both pediatric and adult populations. Although isolated testicular or any other organ recurrence can occur in the pediatric population, it is rare in adults. We present images for an atypical case of the late testicular recurrence of acute lymphoblastic leukemia in a 56-year-old man previously diagnosed with ALL pro-T who was in remission following polychemotherapy (GMALL 2013 protocol) and the allotransplantation of peripheral blood stem cells from a related donor. Five years later (2022), the unilateral testicular relapse of ALL was suspected by imaging and diagnosed by immunophenotyping from sperm fluid infiltrated with atypical cells with an immunophenotype concordant with that of the underlying disease (ALL T). Bone marrow aspiration and biopsy showed no evidence of systemic leukemia relapse. Testicular ablation or chemotherapy and irradiation were considered. Given the strictly testicular relapse, orchiectomy would have been useful, but given the abdominal adenopathy, a chemotherapy course with HyperCVAD Block A was first required. Testicular relapse can occur at any age, and the recognition of this is important as it may be the first manifestation of systemic relapse.

The RAS-signaling-pathway-mutation-related prognosis in B-cell acute lymphoblastic leukemia: A report from South China children's leukemia group.

The next-generation sequencing technologies application discovers novel genetic alterations frequently in pediatric acute lymphoblastic leukemia (ALL). RAS signaling pathway mutations at the time of relapse ALL frequently appear as small subclones at the time of onset, which are considered as the drivers in ALL relapse. Whether subclones alterations in the RAS signaling pathway should be considered for risk group stratification of ALL treatment is not decided yet. In this work, we investigate the RAS signaling pathway mutation spectrum and the related prognosis in pediatric ALL. We employed an NGS panel comprising 220 genes. NGS results were collected from 202 pediatric ALL patients. 155 patients (76.7%) harbored at least one mutation. The incidences of RAS signaling pathway mutations are different significantly between T-ALL and B-ALL. In B-ALL, the RAS pathway is mostly involved, and NRAS (17.6%), KRAS (22.7%), and PTPN11 (7.7%) were the three most frequently mutated genes. Co-occurring mutations of CREBBP and NRAS, FLT3, or PTPN11 (p=0.002, p=0.009, and p=0.003, respectively) were found in this cohort. The 3-year RFS rates for the RAS signaling pathway mutation-positive and negative cases was 76.5 % versus 89.7 % (p=0.012). Four cases relapsed in the lately 3years were RAS signaling pathway mutation-positive. RAS signaling pathway mutation is an important biomarker for poorer relapse-free survival in pediatric B-ALL patients despite good early MRD levels.

The role of quiescent thymic progenitors in TAL/LMO2-induced T-ALL chemotolerance

Relapse in T-cell acute lymphoblastic leukemia (T-ALL) may signify the persistence of leukemia-initiating cells (L-ICs). Ectopic TAL1/LMO expression defines the largest subset of T-ALL, but its role in leukemic transformation and its impact on relapse-driving L-ICs remain poorly understood. In TAL1/LMO mouse models, double negative-3 (DN3; CD4−CD8−CD25+CD44−) thymic progenitors harbored L-ICs. However, only a subset of DN3 leukemic cells exhibited L-IC activity, and studies linking L-ICs and chemotolerance are needed. To investigate L-IC heterogeneity, we used mouse models and applied single-cell RNA-sequencing and nucleosome labeling techniques in vivo. We identified a DN3 subpopulation with a cell cycle–restricted profile and heightened TAL1/LMO2 activity, that expressed genes associated with stemness and quiescence. This dormant DN3 subset progressively expanded throughout leukemogenesis, displaying intrinsic chemotolerance and enrichment in genes linked to minimal residual disease. Examination of TAL/LMO patient samples revealed a similar pattern in CD7+CD1a− thymic progenitors, previously recognized for their L-IC activity, demonstrating cell cycle restriction and chemotolerance. Our findings substantiate the emergence of dormant, chemotolerant L-ICs during leukemogenesis, and demonstrate that Tal1 and Lmo2 cooperate to promote DN3 quiescence during the transformation process. This study provides a deeper understanding of TAL1/LMO-induced T-ALL and its clinical implications in therapy failure.

Application of prime editing system to introduce TP53 R248Q hotspot mutation in acute lymphoblastic leukemia cell line.

In childhood acute lymphoblastic leukemia (ALL), TP53 gene mutation is associated with chemoresistance in a certain population of relapsed cases. To directly verify the association of TP53 gene mutation with chemoresistance of relapsed childhood ALL cases and improve their prognosis, the development of appropriate human leukemia models having TP53 mutation in the intrinsic gene is required. Here, we sought to introduce R248Q hotspot mutation into the intrinsic TP53 gene in an ALL cell line, 697, by applying a prime editing (PE) system, which is a versatile genome editing technology. The PE2 system uses an artificial fusion of nickase Cas9 and reverse-transcriptase to directly place new genetic information into a target site through a reverse transcriptase template in the prime editing guide RNA (pegRNA). Moreover, in the advanced PE3b system, single guide RNA (sgRNA) matching the edited sequence is also introduced to improve editing efficiency. The initially obtained MDM2 inhibitor-resistant PE3b-transfected subline revealed disrupted p53 transactivation activity, reduced p53 target gene expression, and acquired resistance to chemotherapeutic agents and irradiation. Although the majority of the subline acquired the designed R248Q and adjacent silent mutations, the insertion of the palindromic sequence in the scaffold hairpin structure of pegRNA and the overlap of the original genomic DNA sequence were frequently observed. Targeted next-generation sequencing reconfirmed frequent edit errors in both PE2 and PE3b-transfected 697 cells, and it revealed frequent successful edits in HEK293T cells. These observations suggest a requirement for further modification of the PE2 and PE3b systems for accurate editing in leukemic cells.

Abstract 5662: PDCD1 and CD48 significantly impact cancer recurrence and survival in pediatric acute lymphoblastic leukemia

Abstract Introduction: Immune checkpoints (ICPs) play a critical role in modulating the immune response, maintaining self-tolerance, and preventing excessive immune system activation. Dysregulation of immune checkpoints has been implicated in cancer progression and treatment resistance. In this study, we aimed to screen for dysregulated immune checkpoint genes that might be associated with cancer recurrence in pediatric acute lymphoblastic leukemia (ALL) following a course of cancer treatment. We hypothesized that certain ICPs would be significantly dysregulated in relapsed ALL patients, potentially providing insights into the underlying mechanisms driving therapy resistance and disease recurrence. Methods: 51 ICP genomic data (gene expression, copy number alterations (CNAs), and mutation) of133 patients with relapse information [relapse-free (n=29) and relapsed (n=104)] extracted from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) were examined in the study. Patient’s t-test (p-value < 0.05) was used to identify significant genetic factors between relapse-free and relapsed patients. Free and overall survival analyses were performed using log-rank test (p-value < 0.05) based on patient gene expression profiles. Results: Among the 51 genes examined, PDCD1, PVR, CD70, and CD48 were significantly upregulated in relapsed patients compared with relapse-free patients (P < 0.05). No significant CNAs nor mutations were detected in these four genes. Patients with high expression profiles of PDCD1 and CD48 at diagnosis were 1.71 and 1.47 more likely to relapse compared to patients with low expression profiles, respectively (P < 0.05). Furthermore, the upregulation of PDCD1 (P= 0.0004, HR= 1.972) and CD48 (P= 0.0344, HR= 1.533) demonstrated significantly increased mortality rates in patients following treatment, as indicated by overall survival analyses. Conclusion: The upregulation of PDCD1 and CD48 was significantly associated with relapse and survival of ALL patients. Promisingly, these two ICPs can potentially be used as prognostic biomarkers for relapse risk and rationale for alternative therapeutic strategies. Our study suggests that targeting PDCD1 and CD48 might be beneficial in enhancing the treatment efficiency and thereby reducing the recurrence risk. The study was funded by the Deputyship for Research and Innovation, Ministry of Education, Saudi Arabia (DRI-KSU-1273). Citation Format: Shatha Fawaz Alotaibi, Lames Abuhadi, Noura Alolyani, Moureq R. Alotaibi, Ali R. Alhoshani, Homood As Sobeai. PDCD1 and CD48 significantly impact cancer recurrence and survival in pediatric acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5662.

Abstract 5920: Inhibition of TBL1 and β-catenin interaction sensitizes acute lymphoblastic leukemia to chemotherapy

Abstract BACKGROUND: Relapse of T-cell acute lymphoblastic leukemia (T-ALL) and B-cell acute lymphoblastic leukemia (B-ALL) post-chemotherapy or post-immunotherapy remains a therapeutic problem warranting novel therapeutic approaches. Aberrant Wnt pathway activation is a common feature in ALL as Wnt activation through β-catenin is involved in self- renewal of drug resistant leukemia cells. A therapeutical approach to target Wnt signaling in T-ALL and B-ALL remains elusive. Here, we focus on the effect of transducin β-like protein 1 (TBL1) inhibitor tegavivint in combination with chemotherapy in T-ALL and B-ALL. We hypothesize that interrupting the binding of TBL1 to β-catenin abrogates leukemia cell survival and test if tegavivint sensitizes these cells to chemotherapeutic agents such as VDL (Vincristine, Dexamethasone, L-asparaginase) as part of preclinical evaluation of tegavivint in T- and B-cell ALL. METHODS: Four T-ALL cell lines one patient-derived T-ALL case, B-ALL cell lines and eight patient-derived B-ALL cases were used in vitro. We performed cytotoxicity studies using Annexin V/7AAD stainings and flow cytometry or Trypanblue counts to exclude dead cells, western blots, and co-immunoprecipitation assays to investigate effects of TBL-1 inhibition using tegavivint on β-catenin-mediated signaling. Tegavivint was injected intraperitoneally along with chemotherapeutic drugs. RESULTS: β-catenin and TBL1 were uniformly expressed in all T-ALL and B-ALL cells as determined by western blotting, albeit at different levels. Tegavivint decreases β-catenin protein expression as seen through western blot as well as decreases the binding of TBL1 to β-catenin as seen through co-immunoprecipitation (co-IP) in both the T-ALL and B-ALL samples. We also determined that tegavivint as a monotherapy induced apoptosis in both cell lines and patient samples at as little of a dose of 5nM after 24 hours of incubation using Annexin-V/DAPI staining by flow cytometry. We observed that tegavivint can sensitize all cases to chemotherapy (V: Vincristine, D: Dexamethasone, L:L-Asparaginase or Peg-Asparaginase) within 24 hours of incubation. Lastly, in vivo evaluation of tegavivint showed that tegavivint alone and in combination with VD chemotherapy significantly extends survival of NSG mice engrafted with patient-derived T-ALL and B-ALL compared to control treated mice. CONCLUSION: Our preliminary data shows that T-ALL and B-ALL are sensitive to TBL1-β-catenin inhibition using tegavivint as a monotherapy. Tegavivint can also sensitize T-ALL and B-ALL to chemotherapy (VDL). As our data supports our hypothesis that TBL-1-β-catenin inhibition is a new target in ALL therapy, further studies are in progress to preclinically evaluate this approach for clinical care. Citation Format: Samantha Hurwitz, Rachel Friedmann, Tatiana Fourfouris, Ki Jun Lee, Zesheng Wan, Chintan Parekh, Fariba Navid, Deepa Bhojwani, Kimberly Holloway, Yong-Mi Kim. Inhibition of TBL1 and β-catenin interaction sensitizes acute lymphoblastic leukemia to chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5920.

Abstract 3952: Multiomic single-cell tumor evolution models of minimal residual disease in pediatric B-cell acute lymphoblastic leukemia

Abstract Detection of minimal residual disease (MRD) after initial diagnosis (IDX) and therapy is a strong prognostic marker for relapse in pediatric B-cell acute lymphoblastic leukemia (B-ALL). Previous studies have explored clonal genetic and gene expression changes between initial diagnosis and relapse. However, studying tumor cells present at MRD is challenging due to their low abundance. Examining the genomic profiles of leukemia cells that resist induction chemotherapy and understanding their evolutionary relationship to cells present at diagnosis may lead to a better understanding of the cells that eventually seed relapse. We analyzed somatic point mutations, indels, and copy number variants from 41 pediatric B-ALL patients with high-risk B-ALL. We specifically focused on patients from the following four common high-risk subtypes: KMT2A-rearranged, Ph+, Ph-like, and iAMP21, who had detectable disease at the end of induction. Leukemic burden at end-induction (day 29) ranged from 0.03% to 66.00%. Data were generated in partnership with the National Cancer Institute’s Human Tumor Atlas Network and the Children’s Oncology Group. Our data set of 41 patients includes 39 with paired initial diagnostic and end-induction samples that we used to create tumor evolution models based on single cells across disease stages. We produced single-cell multiome gene expression (scRNA) and chromatin accessibility (scATAC) profiles (10x Genomics) with a median of 7428 leukemic blast cells at IDX (range: 2490-14219) and 1907 at MRD (range: 240-10167) after filtering. We called somatic mutations from scRNA and scATAC using SComatic and Monopogen, and we detected copy number changes using Numbat and EpiAneufinder. We also designed a targeted DNA sequencing panel including 335 variants based on B-ALL literature and database searches to produce scDNA (Mission Bio) for 24 patients (16 IDX-MRD pairs) with a median of 2346 cells profiled at IDX (range: 340-8849) and 1828 at MRD (range: 596-5133). We built tumor phylogenies based on somatic SNVs and CNVs with COMPASS. Using multiple tools and complementary single-cell omics data types to detect somatic changes improved our confidence in the events used for tumor evolution tree construction. Our approach allowed us to define recurrent genomic events and patterns across pediatric B-ALL subtypes and to describe the clonal evolution of cells measured at initial diagnostic and end-induction disease stages. We were also able to link cell-specific mutation events to their transcriptional and epigenomic signatures, including mapping mutation events along the B-cell development trajectory and within differentially expressed gene pathways. Some cases showed dramatic shifts in subclonal structure between IDX and MRD that may be related to therapy-induced clonal selection, such as a loss of NRAS hotspot mutation. Citation Format: Steven M. Foltz, Avi Loren, Changya Chen, Rushabh Mehta, Elizabeth Li, Jason Xu, Fatemeh Alikarami, Kathrin M. Bernt, Kai Tan. Multiomic single-cell tumor evolution models of minimal residual disease in pediatric B-cell acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3952.

Case report: Donor lymphocyte infusion and blinatumomab as treatment for acute lymphoblastic leukemia relapse after allogeneic hematopoietic stem cell transplantation

To date, the effect of blinatumomab and donor lymphocyte infusion association as a salvage treatment for acute lymphoblastic leukemia (ALL) relapse after allogeneic transplant procedure is still unknown. Here, we report a case report of a patient with early relapse of ALL after allogeneic hematopoietic stem cell transplant successfully treated with a combination of blinatumomab and DLI.

[Clinical features and prognostic analysis of testicular relapse in pediatric acute lymphoblastic leukemia].

Objective: To investigate the clinical features and prognosis of testicular relapse in pediatric acute lymphoblastic leukemia (ALL). Methods: Clinical data including the age, time from initial diagnosis to recurrence, relapse site, and therapeutic effect of 37 pediatric ALL with testicular relapse and treated in Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences between November 2011 and December 2022 were analyzed retrospectively. Patients were grouped according to different clinical data. Kaplan-Meier analysis was used to evaluate the overall survival (OS) rate and event free survival (EFS) rate for univariate analysis, and Cox proportional-hazards regression model was used to evaluate the influencing factors of OS rate and EFS rate for multivariate analysis. Results: The age at initial diagnosis of 37 pediatric testicular relapse patients was (5±3) years and the time from initial diagnosis to testicular recurrence was (37±15) months. The follow-up time was 43 (22, 56) months. Twenty-three patients (62%) were isolated testis relapse. The 5-year OS rate and EFS rate of the 37 relapsed children were (60±9) % and (50±9) % respectively. Univariate analysis showed that the 2-year EFS rate in the group of patients with time from initial diagnosis to testicular recurrence >28 months was significantly higher than those ≤28 months ((69±10)% vs. (11±11)%, P<0.05), 2-year EFS rate of the isolated testicular relapse group was significantly higher than combined relapse group ((66±11)% vs. (20±13) %, P<0.05), 2-year EFS rate of chimeric antigen receptor T (CAR-T) cell treatment after relapse group was significantly higher than without CAR-T cell treatment after relapse group ((78±10)% vs. (15±10)%, P<0.05). ETV6-RUNX1 was the most common genetic aberration in testicular relapsed ALL (38%, 14/37). The 4-year OS and EFS rate of patients with ETV6-RUNX1 positive were (80±13) % and (64±15) %, respectively. Multivariate analysis identified relapse occurred≤28 months after first diagnosis (HR=3.09, 95%CI 1.10-8.72), combined relapse (HR=4.26, 95%CI 1.34-13.52) and CAR-T cell therapy after relapse (HR=0.15,95%CI 0.05-0.51) were independent prognostic factors for 2-year EFS rate (all P<0.05). Conclusions: The outcome of testicular relapse in pediatric ALL was poor. They mainly occurred 3 years after initial diagnosis. ETV6-RUNX1 is the most common abnormal gene.Patients with ETV6-RUNX1 positive often have a favorable outcome. Early relapse and combined relapse indicate unfavorable prognosis, while CAR-T cell therapy could significantly improve the survival rate of children with testicular recurrence.

The Role of Cytogenetic Rearrangements in the Formation of Resistance in Relapse of Acute Lymphoblastic Leukemia

The Role of Cytogenetic Rearrangements in the Formation of Resistance in Relapse of Acute Lymphoblastic Leukemia

Disseminated Nocardia nova in a child with relapsed acute lymphoblastic leukemia: a case report

BackgroundNocardiosis is a rare infection that typically results from inhalation of or inoculation with Nocardia organisms. It may cause invasive disease in immunocompromised patients. This case describes nocardiosis with bacteremia and pulmonary involvement in a child with a hematologic malignancy.Case presentationA boy with testicular relapsed acute lymphoblastic leukemia with marrow involvement presented with sudden onset of fever, body aches, headaches, chills, and moderate respiratory distress during continuation 2 chemotherapy. Radiographic imaging demonstrated consolidation and ground glass opacities in bilateral lower lungs. Central line blood cultures grew Nocardia nova complex, prompting removal of the central line and initiation of triple therapy with imipenem-cilastatin, linezolid, and trimethoprim-sulfamethoxazole with rapid improvement of symptoms. Antibiotic susceptibilities showed a multidrug-susceptible isolate. The patient is anticipated to remain on trimethoprim-sulfamethoxazole for at least 12 months.ConclusionsIn an immunocompromised child, blood cultures, chest imaging, and head imaging can aid in the diagnosis of disseminated nocardiosis. Long-term antibiotic therapy is necessary, guided by the organism and simplified with the results of antimicrobial susceptibility testing.

TBI, etoposide, and cyclophosphamide conditioning for intermediate-risk relapsed childhood acute lymphoblastic leukemia.

In children with intermediate-risk relapsed acute lymphoblastic leukemia (ALL), allogeneic hematopoietic stem cell transplantation (allo-HSCT) has markedly improved the outcome of patients with an unsatisfactory minimal residual disease (MRD) response. Total body irradiation (TBI), etoposide (ETP), and cyclophosphamide (CY) have been shown to be equivalent to or better than TBI + ETP for conditioning, so we hypothesized that even greater survival could be achieved due to recent advances in HSCT and supportive care. We prospectively analyzed the efficacy and safety of allo-HSCT with a unified conditioning regimen of TBI + ETP + CY in children with intermediate-risk relapsed ALL, based on MRD in the bone marrow after induction, from the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) ALL-R08-II nationwide cohort (UMIN000002025). Twenty patients with post-induction MRD ≥ 10-3 and two not evaluated for MRD underwent allo-HSCT. Engraftment was confirmed in all patients, and no transplantation-related mortality was observed. The 3-year event-free survival and overall survival rates after transplantation were 86.4% ± 7.3% and 95.5% ± 4.4%, respectively. Allo-HSCT based on post-induction MRD with TBI + ETP + CY conditioning was feasible in Japanese children with intermediate-risk relapsed ALL.

Molecular biology techniques for assessing the loss of HLA heterozygosity after allogeneic hematopoietic stem cell transplantation in children with acute leukemia

According to several observations, up to a third of post-transplant relapses in childhood acute leukemia are associated with the loss of heterozygosity of the major histocompatibility complex (HLA). Furthermore, the inefficacy of the graft-versus-leukemia reaction, as evidenced by the lack of therapeutic effect from the infusion of donor lymphocytes, indicates the need for timely detection of this marker to change the treatment strategy in the post-transplant period. To detect the loss of HLA heterozygosity, the method using the commercial KMR-HLA system and analysis using next-generation sequencing (NGS), as well as the method based on the analysis of highly polymorphic STR and VNTR markers located in the HLA loci region on the short arm of chromosome 6, are widely used. The primary objective of our study was to compare the informativeness of these approaches in diagnosing HLA heterozygosity loss in children during the post-transplant period. The obtained data on the frequency of detecting HLA heterozygosity loss were comparable to the literature data and constituted 23 % of cases of post-transplant relapse of B-cell acute lymphoblastic leukemia, 33 % of cases of T-cell acute lymphoblastic leukemia, and 23% of cases of acute myeloid leukemia. We also demonstrated that the method based on STR marker analysis has sensitivity comparable to allele-specific PCR and NGS sequencing methods. Meanwhile, preliminary sorting of the blast population increases the sensitivity of STR analysis and can be recommended in routine practice.

A multicenter study of posttransplantation low-dose inotuzumab ozogamicin to prevent relapse of acute lymphoblastic leukemia

AbstractThe curative potential of allogeneic hematopoietic transplantation (allo-HCT) in patients with acute lymphoblastic leukemia (ALL) is hampered by relapse. Inotuzumab ozogamicin (INO) is an anti-CD22 monoclonal antibody bound to calicheamicin, which has significant activity against ALL. We hypothesized that low-dose INO would be safe and feasible after allo-HCT. Therefore, we conducted a phase 1 study to determine the dose and safety in this setting. Patients were eligible if they were aged 16 to 75 years, had undergone allo-HCT for CD22+ ALL, were in complete remission (CR) after allo-HCT, had high risk of recurrence, were between day 40 and 100 after allo-HCT with adequate graft function, and did not have a history of sinusoidal obstruction syndrome (SOS). The objectives of this trial were to define INO maximum tolerated dose (MTD), to determine post–allo-HCT INO safety, and to measure 1-year progression-free survival (PFS). The trial design followed a “3+3” model. The treatment consisted of INO given on day 1 of 28-day cycles. Dose levels were 0.3 mg/m2, 0.4 mg/m2, 0.5 mg/m2, and 0.6 mg/m2. Median age was 44 years (range, 17-66 years; n = 18). Disease status at transplantation was first CR (n = 14) or second CR or beyond (n = 4). Preparative regimen was of reduced intensity in 72% of patients who received transplantation. Most common toxicity was thrombocytopenia. There were no instances of SOS; the MTD was 0.6 mg/m2. One-year nonrelapse mortality was 5.6%. With a median follow-up of 18.1 months (range, 8.6-59 months) 1-year post–allo-HCT PFS and overall survival is 89% and 94%, respectively. Low-dose INO has a favorable safety profile and was associated with high rates of 1-year PFS. This trial was registered at www.clinicaltrials.gov as #NCT03104491.

Testicular leukaemic infiltration in relapsed acute lymphoblastic leukaemia: a case report

Abstract Background Although paediatric patients with acute lymphoblastic leukaemia (ALL) have improved survival following modern chemotherapy treatment, disease relapses still occur in 20–25% of them. Our case had relapsed ALL with testicular leukaemic infiltration, which is rare, with less than 2% incidence. Case presentation We describe a case of an 11-year-old boy with a background history of ALL presenting with painless unilateral scrotal swelling. An initial ultrasound of the testes showed heterogeneity throughout with hypervascularity on colour-flow imaging on the affected testis. Some areas are hypoechoic with dilated tubules. The histopathology of the follow-up testicular biopsy revealed malignant cells and leukaemic infiltration. Patient subsequently received chemotherapy treatment at another centre. Conclusions Testicular relapse of ALL is relatively rare with the use of improved contemporary frontline treatment with better outcomes. With its non-specific symptoms, radiological imaging can significantly facilitate timely diagnosis and contribute to appropriate further management and improved prognosis.

Diagnostic and therapeutic advances in adults with acute lymphoblastic leukemia in the era of gene analysis and targeted immunotherapy.

Acute lymphoblastic leukemia (ALL) is one of the most rapidly changing hematological malignancies with advanced understanding of the genetic landscape, detection methods of minimal residual disease (MRD), and the development of immunotherapeutic agents with good clinical outcomes. The annual incidence of adult ALL in Korea is 300-350 patients per year. The WHO classification of ALL was revised in 2022 to reflect the molecular cytogenetic features and suggest new adverse- risk subgroups, such as Ph-like ALL and ETP-ALL. We continue to use traditional adverse-risk features and cytogenetics, with MRD-directed post-remission therapy including allogeneic hematopoietic cell transplantation. However, with the introduction of novel agents, such as ponatinib, blinatumomab, and inotuzumab ozogamicin incorporated into frontline therapy, good MRD responses have been achieved, and overall survival outcomes are improving. Accordingly, some clinical trials have suggested a possible era of chemotherapy-free or transplantation-free approaches in the near future. Nevertheless, relapse of refractory ALL still occurs, and some poor ALL subtypes, such as Ph-like ALL and ETP-ALL, are unsolved problems for which novel agents and treatment strategies are needed. In this review, we summarize the currently applied diagnostic and therapeutic practices in the era of advanced genetic analysis and targeted immunotherapies in United States and Europe and introduce real-world Korean data.

RNA-seq–based miRNA signature as an independent predictor of relapse in pediatric B-cell acute lymphoblastic leukemia

AbstractAberrant micro-RNA (miRNA) expression profiles have been associated with disease progression and clinical outcome in pediatric cancers. However, few studies have analyzed genome-wide dysregulation of miRNAs and messenger RNAs (mRNAs) in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL). To identify novel prognostic factors, we comprehensively investigated miRNA and mRNA sequencing (miRNA-seq and mRNA-seq) data in pediatric BCP-ALL samples with poor outcome. We analyzed 180 patients, including 43 matched pairs at diagnosis and relapse. Consensus clustering of miRNA expression data revealed a distinct profile characterized by mainly downregulation of miRNAs (referred to as an miR-low cluster [MLC]). The MLC profile was not associated with any known genetic subgroups. Intriguingly, patients classified as MLC had significantly shorter event-free survival (median 21 vs 33 months; log-rank P = 3 ×10−5). Furthermore, this poor prognosis was retained even in hyperdiploid ALL. This poor prognostic MLC profiling was confirmed in the validation cohort. Notably, non-MLC profiling at diagnosis (n = 9 of 23; Fisher exact test, P = .039) often changed into MLC profiling at relapse for the same patient. Integrated analysis of miRNA-seq and mRNA-seq data revealed that the transcriptional profile of MLC was characterized by enrichment of MYC target and oxidative phosphorylation genes, reduced intron retention, and low expression of DICER1. Thus, our miRNA-mRNA integration approach yielded a truly unbiased molecular stratification of pediatric BCP-ALL cases based on a novel prognostic miRNA signature, which may lead to better clinical outcomes.

The Role of miRNAs in Childhood Acute Lymphoblastic Leukemia Relapse and the Associated Molecular Mechanisms.

Acute lymphoblastic leukemia (ALL) is the most common cancer in children worldwide. Although ALL patients' overall survival rates in wealthy countries currently surpass 80%, 15-20% of patients still experience relapse. The underlying mechanisms of relapse are still not fully understood, and little progress has been made in treating refractory or relapsed disease. Disease relapse and treatment failure are common causes of leukemia-related death. In ALL relapse, several gene signatures have been identified, but it is also important to study miRNAs involved in ALL relapse in an effort to avoid relapse and to achieve better survival rates since miRNAs regulate target genes that participate in signaling pathways involved in relapse, such as those related to drug resistance, survival signals, and antiapoptotic mechanisms. Several miRNAs, such as miR-24, miR-27a, miR-99/100, miR-124, miR-1225b, miR-128b, miR-142-3p, miR-155 and miR-335-3p, are valuable biomarkers for prognosis and treatment response in ALL patients. Thus, this review aimed to analyze the primary miRNAs involved in pediatric ALL relapse and explore the underlying molecular mechanisms in an effort to identify miRNAs that may be potential candidates for anti-ALL therapy soon.

Histone deacetylase inhibition sensitizes p53-deficient B-cell precursor acute lymphoblastic leukemia to chemotherapy.

In pediatric Acute Lymphoblastic Leukemia (ALL), mutations/deletions affecting the TP53 gene are rare at diagnosis. However, at relapse about 12% of the patients show TP53 aberrations, predicting a very poor outcome. Since p53-mediated apoptosis is an endpoint for many cytotoxic drugs, loss of p53 function frequently leads to therapy failure. In this study, we show that CRISPR/Cas9-induced loss of TP53 drives resistance to a large majority of drugs used to treat relapsed ALL, including novel agents such as inotuzumab ozogamicin. Using a high throughput drug screen, we identified the histone deacetylase inhibitor romidepsin as a potent sensitizer of drug responsiveness, improving sensitivity to all chemotherapies tested. In addition, romidepsin improved the response to cytarabine in TP53 deleted ALL cells in vivo. Together, these results indicate that the histone deacetylase inhibitor romidepsin can improve the efficacy of salvage therapies for relapsed TP53-mutated leukemia. Since romidepsin has been approved for clinical use in some adult malignancies, these findings may be rapidly translated to clinical practice.