Translocation t(1;19)(q23;p13) in adult acute lymphoblastic leukemia - a distinct subtype with favorable prognosis

Case of B-acute lymphoblastic leukaemia with t(1;19)(q23;p13.3) TCF3::PBX1 and co-occurring CBL mutation in an elderly patient

The t(1;19) (q23;p13) TCF3::PBX1 is a well-described, recurring chromosomal abnormality in B-acute lymphoblastic leukaemia (B-ALL) that has historically been associated with a worse prognosis in paediatric patients. Gene expression profiling has demonstrated that TCF3::PBX1 results in a distinct subtype of B-ALL, leading to its recognition in the most recent WHO and ICC classifications. Though initially believed to be a poor prognostic sign in the adult population, emerging evidence suggests its presence may instead be intermediate or even favourable in B-ALL. However, adults with TCF3::PBX1 are typically younger and often qualify for treatment with paediatric-inspired regimens. Thus, the prognostic significance in this population remains unclear. This translocation appears to be very rare in older adults with B-ALL and its predictive and prognostic nature in this population is unknown. Herein, we explore a case of this translocation occurring in a patient in her 70s. She initially presented to the emergency department with abdominal pain and thrombocytopenia and was subsequently diagnosed with B-ALL. In addition to t(1;19) (q23;p13), a pathologic mutation in the CBL gene was identified. CBL mutations have been implicated in cancer progression and are mostly described in paediatric B-ALL. She was treated with modified Ph-negative EWALL induction (Vincristine, Idarubicin, dexamethasone) and achieved a complete remission. However, she subsequently experienced an early relapse and was refractory to targeted therapy with blinatumomab. After treatment with inotuzumab ozogamicin, she achieved a second complete remission. Unfortunately, she then suffered a central nervous system (CNS) relapse and passed away from complications of her disease. This case serves as an example of the heterogeneous nature of B-ALL. It demonstrates that patients with ostensibly favourable prognostic factors may experience poor response rates to traditional chemotherapy as well as targeted salvage agents. It also illustrates the challenges of treating B-ALL in the elderly population.

Real world outcome of B ALL with t (1; 19) (q23; p13)/TCF3::PBX1 in adolescents and adults treated with intensive regimes

Significant heterogeneity has been reported in outcome of Acute lymphoblastic leukemia with t(1;19)(q23;p13)/TCF3::PBX1 in adolescents and adults leading to a lack of consensus on precise risk stratification. We evaluated clinical outcome of 17 adult ALL cases (≥15 years) with this genotype treated on intensive regimes.13/17 received COG0232 and 4/17 cases received UK-ALL protocol. All achieved CR (100%) with above treatment. End of induction MRD was evaluated in 14/17 cases of which 11 (78.5%) achieved MRD negativity. Total nine patients relapsed (7 marrows, 2 CNS). Overall survival at 2 years was 53.3%. The 2 year estimated PFS was 42.9%. The 2 years CIR was 54.2%. Adults with this genotype perform poorly despite early favorable response. Incorporation of novel immunotherapies and prompt HSCT should be strongly considered with this genotype. Targeted NGS panels for additional genetic aberrations can further help in risk stratifying and guiding therapy for this genotype.

Molecular characterization of TCF3::PBX1 chromosomal breakpoints in acute lymphoblastic leukemia and their use for measurable residual disease assessment

The translocation t(1;19)(q23;p13) with the resulting chimeric TCF3::PBX1 gene is the third most prevalent recurrent chromosomal translocation in acute lymphoblastic leukemia and accounts for 3-5% of cases. The molecular background of this translocation has been incompletely studied, especially in adult cases. We characterized the chromosomal breakpoints of 49 patients with TCF3::PBX1 and the corresponding reciprocal PBX1::TCF3 breakpoints in 15 cases at the molecular level, thus providing an extensive molecular overview of this translocation in a well-defined study patient population. Breakpoints were found to be remarkably clustered not only in TCF3 but also in PBX1. No association with DNA repeats or putative cryptic recombination signal sequence sites was observed. A simplified detection method for breakpoint identification was developed and the feasibility of patient-specific chromosomal break sites as molecular markers for detecting measurable residual disease (MRD) was explored. A highly sensitive generic real-time PCR for MRD assessment using these breakpoint sequences was established that could serve as a useful alternative to the classical method utilizing rearranged immune gene loci. This study provides the first extensive molecular data set on the chromosomal breakpoints of the t(1;19)/TCF3::PBX1 aberration in adult ALL. Based on the obtained data a generic MRD method was developed that has several theoretical advantages, including an on average higher sensitivity and a greater stability of the molecular marker in the course of disease.

Adult acute lymphoblastic leukemia in a resource-constrained setting: outcomes after expansion of genetic evaluation

Acute lymphoblastic leukemia (ALL) is a challenging disease with a growing genetic landscape, even though there is substantial gap between developed and non-developed countries when it comes to availability of such new technologies. This manuscript reports a 5-year retrospective cohort of newly diagnosed ALL patients and their genetic findings and outcomes. An expanded genetic evaluation by using FISH and RT-PCR was implemented, aiming to identify Ph-like alterations. Patients were treated according to our local protocol, which allocated patients according to age and Philadelphia-chromosome status. A total of 104 patients was included, with median age of 37.5 years. Philadelphia chromosome was detected in 33 cases of B-lineage. Among 45 Ph-negative B-lineage, after excluding KMT2A or TCF3-PBX1 cases, we identified 9 cases with Ph-like fusion. Ph-positive and Ph-like patients had higher initial WBC (p = 0.06). Out of 104 cases, two cases did not start chemotherapy and an early death rate of 10.8% was found. Allogeneic transplantation was performed in 18 cases, being ten performed in first CR. Three-year overall survival (OS) and 3-year event-free survival were 42.8% and 30.8%, respectively. For patients treated with a pediatric regimen, 3-year OS was 52.5%. Extramedullary disease (HR 0.42) and platelet counts (HR 0.9) were independently associated with OS. We still face excessive non-relapse mortality that compromises our results. Alternative strategies implementing FISH and RT-PCR are feasible and able to identify Ph-like fusions. Delays in allogeneic transplantation, as well as the unavailability of new agents, impact long-term survival. Measures to decrease early infection are desirable.

B-cell acute lymphoblastic leukaemia: recent discoveries in molecular pathology, their prognostic significance, and a review of the current classification

Acute lymphoblastic leukaemia (ALL) remains a leading cause of non-traumatic death in children, and the majority of adults diagnosed will succumb to the disease. Recent advances in molecular biology and bioinformatics have enabled more detailed genomic analysis and a better understanding of the molecular biology of ALL. A number of recurrent genomic drivers have recently been described, which not only aid in diagnosis and prognostication, but also may offer opportunities for specific therapeutic targeting. The present review summarises B-ALL genomic pathology at diagnosis, including lesions detectable using traditional cytogenetic methods as well as those detected only through advanced molecular techniques.

The clinical outcomes and genomic landscapes of acute lymphoblastic leukemia patients with E2A-PBX1: A 10-year retrospective study

The clinical outcomes and genomic features of E2A-PBX1 (TCF3-PBX1)-positive B-cell acute lymphoblastic leukemia (B-ALL) patients remain unclear. A total of 137 patients carrying E2A-PBX1 among 3164 B-ALL patients between 2009 and 2019 were retrospectively analyzed. The 5-year overall survival (OS) and disease-free survival (DFS) rates of the whole cohort were 68.6% and 61.0%, respectively. Age [DFS, p = 0.037; cumulative incidence of relapse (CIR), p = 0.005] and the level of minimal residual disease (MRD) after induction chemotherapy (OS, p = 0.020; DFS, p = 0.002; CIR, p = 0.006) were independent risk factors. In adolescents/adults, allogeneic hematopoietic stem cell transplantation (allo-HSCT) at first complete remission (CR1) significantly improved the 5-year prognosis (OS, p < 0.001; DFS, p < 0.001; CIR, p < 0.001). Haploidentical HSCT decreased the CIR compared with human leukocyte antigen-matched HSCT in adolescents/adults (p = 0.017). Mutations in PBX1, PAX5, CTCF and SETD2, amplification of AKT3, and deletion of CDKN2A/B were common in the total cohort, while transcriptome differences were found in the cell cycle, nerve growth factor (NGF) signaling pathway and transcriptional regulation by TP53 between adolescents/adults and children. Patients with multiple subclones at diagnosis tended to have unfavorable 3-year prognoses (DFS, p = 0.010; CIR, p = 0.021). Leukemia clones with DNA repair gene mutations showed aggressive and treatment-refractory phenotypes in this subtype of ALL. Our study indicated that age, the level of MRD and DNA repair gene mutations were associated with E2A-PBX1-positive B-ALL outcomes. Allo-HSCT, especially haploidentical HSCT, could improve the prognosis of adolescent/adult patients.

Prognostic heterogeneity of adult B-cell precursor acute lymphoblastic leukaemia patients with t(1;19)(q23;p13)/TCF3-PBX1 treated with measurable residual disease-oriented protocols

The prognosis of t(1;19)(q23;p13)/transcription factor 3-pre-B-cell leukaemia homeobox 1 (TCF3-PBX1) in adolescent and adult patients with acute lymphoblastic leukaemia (ALL) treated with measurable residual disease (MRD)-oriented trials remains controversial. In the present study, we analysed the outcome of adolescent and adult patients with t(1;19)(q23;p13) enrolled in paediatric-inspired trials. The patients with TCF3-PBX1 showed similar MRD clearance and did not have different survival compared with other B-cell precursor ALL patients. However, patients with TCF3-PBX1 had a significantly higher cumulative incidence of relapse, especially among patients aged ≥35 years carrying additional cytogenetic alterations. These patients might benefit from additional/intensified therapy (e.g. immunotherapy in first complete remission with or without subsequent haematopoietic stem cell transplantation).

Molecular-based and antibody-based targeted pharmacological approaches in childhood acute lymphoblastic leukemia

Introduction: Despite the significant survival improvement in childhood acutelymphoblastic leukemia (ALL), 15-20% of patients continue to relapse; outcomes following relapse remain suboptimal and have room for further improvement. Advances in genomics have shed new insights on the biology of ALL, led to the discovery of novel genomically defined ALL subtypes, refined prognostic significance and revealed new therapeutic vulnerabilities.Areas covered: In this review, the authors provide an overview of the genomic landscape of childhood ALL and highlight recent advances in molecular-based and antibody-based pharmacological approaches in the treatment of childhood ALL, from emerging preclinical evidence to published results of completed clinical trials.Expert opinion: Molecularly targeted therapies and immunotherapies have expanded the horizons of ALL therapy and represent promising therapeutic avenues for high-risk and relapsed/refractory ALL. These novel therapies are now moving into frontline ALL therapy and may define new treatment paradigms that aim to further improve survival and reduce chemotherapy-related toxicities in the management of pediatric ALL.