Genetic alterations and MRD refine risk assessment for KMT2A-rearranged B-cell precursor ALL in adults: a GRAALL study

Refining Risk Stratification for B-cell Precursor Adult Acute Lymphoblastic Leukemia Treated With a Pediatric-inspired Regimen by Combining IKZF1 Deletion and Minimal Residual Disease

INTRODUCTION

Minimal residual disease (MRD) is the most important prognostic factor for B-cell acute lymphoblastic leukemia (B-ALL) however nearly 20-30% of patients relapsed even when they achieved negative MRD, how to identify these patients is less addressed. In this study, we aimed to reassess the prognostic significance of MRD and IKZF1 in adult B-ALL patients receiving pediatric chemotherapy regimens.

METHODOLOGY

A total of 202 newly diagnosed adult patients with B-ALL treated at Nanfang Hospital between January 2016 and September 2020 were enrolled in the population-based protocol of the PDT-ALL-2016 trial (NCT03564470), a GRAALL-backbone, peg-aspargase-intensified, antimetabolite-based pediatric-inspired regimen therapy. The validation dataset COG-P9906, which includes complete gene expression profiles and clinical data for 190 samples, is accessible via the NCBI Gene Expression Omnibus (GEO) at the following link: (https://www.ncbi.nlm.nih.gov/geo/), under the accession code GSE11877.

MAIN FINDINGS

B-ALL patients were redefined as standard (MRD-negative and IKZF1wild-type), intermediate (MRD-positive or IKZF1 deletion), and high-risk (MRD-positive and IKZF1 deletion) groups by combining IKZF1 deletion status and MRD. In the PDT-ALL-2016 cohort, patients in the high- and intermediate-risk groups who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) exhibited significantly improved 5-year overall survival (OS), event-free survival (EFS), and lower cumulative incidence of relapse (CIR) compared to those who received chemotherapy alone. In the PDT-ALL-2016 cohort, no significant advantage was observed in the 5-year OS, EFS, and CIR of patients in the standard-risk group who received allo-HSCT compared to those who received chemotherapy.

DISCUSSION

Traditional risk factors, incorporating clinical and cytogenetic features, have been previously evaluated to stratify risks and guide treatment decisions. However, the prognostic strength of this stratified system is limited by the pediatric-inspired protocol background, making it difficult to identify patients with a high risk of relapse. Therefore, in the era of pediatric-inspired protocols, it is imperative to reassess traditional risk factors to identify patients at high risk of recurrence and mortality.In this study, we retrospectively evaluated the combination of MRD and IKZF1 to develop an efficient risk stratification tool for adult patients with B-ALL in the pediatric-inspired chemotherapy era. Moreover, allo-HSCT had distinct efficacy at different risk levels, which means that the decision to perform allo-HSCT may be well guided by this risk classification scheme.

CONCLUSION

In conclusion, based on our cohort study and validation cohort, we demonstrated that the combination of MRD and IKZF1 deletion allows for better risk stratification of adults with B-ALL and that allo-HSCT mitigates the poor prognosis of MRD+ and/or IKZF1del subgroups.

Novel prognostic factors and therapeutic advances in adult acute lymphoblastic leukemia

The prognosis of adult patients with acute lymphoblastic leukemia (ALL) has improved in the last decades. This has been due to the sum of several factors including more precise recognition of the ALL subtypes, refinement of the assessment of prognostic factors, improvement in pediatric-inspired chemotherapy regimens and especially to the incorporation of novel targeted and immune therapeutics, as well as engineered cellular therapies, among others. These therapies were initially developed for relapsed or refractory patients but are now being incorporated into frontline treatment and represent a major step forward in ALL therapy. This review focuses on the recent advances in ALL characterization and especially on the treatment of ALL in adults.

Inotuzumab Ozogamicin and Low-Intensity Chemotherapy in Older Patients With Newly Diagnosed CD22+ Philadelphia Chromosome-Negative B-Cell Precursor Acute Lymphoblastic Leukemia

PURPOSE

The use of inotuzumab ozogamicin (InO), a conjugated anti-CD22 monoclonal antibody, is becoming a promising frontline treatment for older patients with ALL.

PATIENTS AND METHODS

EWALL-INO is an open-label prospective multicenter phase II trial (ClinicalTrials.gov identifier: NCT03249870). Patients age 55 years and older with newly diagnosed CD22+ Philadelphia chromosome-negative (Ph-) B-cell precursor (BCP) ALL were eligible. After a prephase, a first induction consisting of vincristine, dexamethasone, and three injections of InO (0.8 mg/m2 day 1, 0.5 mg/m2 day 8/day 15) was followed by a second induction combining cyclophosphamide, dexamethasone, and two injections of InO (0.5 mg/m2 day 1/day 8). Responders received up to six cycles of chemotherapy consolidation and 18-month chemotherapy maintenance. Allotransplant was allowed after three consolidations. The primary end point was 1-year overall survival (OS).

RESULTS

Between December 2017 and March 2022, 131 patients (median age 68 years) were included. Three patients died during induction 1 (n = 130), two from multiple organ failure and one from hemorrhage, and none during induction 2 (n = 120). After induction 2, 90% of the patients achieved complete remission (CR) or CR with incomplete platelet recovery (CRp) and 80% had measurable residual disease (MRD2) <10-4. Among responders (n = 119), 47 relapsed and 14 died in CR/CRp. One-year OS, relapse-free survival (RFS), and cumulative incidence of relapse (CIR) rates were 73.2%, 66%, and 25%, respectively. High-risk cytogenetics and lower CD22 expression (<70%) were associated with worse OS, while both high-risk cytogenetics and MRD2 ≥10-4 were associated with lower RFS and higher CIR. The 10 allotransplanted patients had very favorable outcomes (90% 2-year OS/RFS and no relapse). Only one nonfatal sinusoidal obstructive syndrome was documented during the study.

CONCLUSION

Our results support InO's use in first-line regimens for older patients with CD22+ Ph- BCP-ALL.

Preferential Genetic Pathways Lead to Relapses in Adult B-Cell Acute Lymphoblastic Leukemia

Adult B-cell acute lymphoblastic leukemia (B-ALL) is characterized by genetic heterogeneity and a high relapse rate, affecting over 40% of adults. However, the mechanisms leading to relapse in adults are poorly understood. Forty-four adult B-ALL patients were studied at both diagnosis and relapse by next-generation sequencing (NGS). Four main genetic pathways leading to relapse in adults were identified: IKZF1plus genetic profile, RAS mutations and TP53 alterations in Ph-negative B-ALL and acquisition of ABL1 mutations in Ph-positive patients. The most frequently deleted gene at diagnosis was IKZF1 (52%), and 70% of these patients had IKZF1plus profile. Notably, 88% of patients with IKZF1plus at diagnosis retained this genetic profile at relapse. Conversely, the acquisition of RAS mutations or the expansion of subclones (normalized variant allele frequency < 25%) present from diagnosis were observed in 24% of Ph-negative patients at relapse. In addition, 24% of relapses in the Ph-negative cohort could potentially be driven by TP53 alterations. Of these cases, five presented from diagnosis, and four emerged at relapse, mostly as "double-hit" events involving both TP53 deletion and mutation. In Ph-positive B-ALL, the main genetic finding at relapse was the acquisition of ABL1 mutations (86%). Three clonal evolution patterns were identified: the persistent clone trajectory (25%), the expanding clone trajectory (11%) and the therapy-boosted trajectory (48%). Our results reveal the presence of preferential biological pathways leading to relapse in adult B-ALL. These findings underscore the need for personalized therapeutic strategies to improve clinical outcomes in adult patients with B-ALL.

Transplant in ALL: who, when, and how?

Allogeneic hematopoietic stem cell transplantation (allo-HCT) remains a cornerstone in the treatment of high-risk acute lymphoblastic leukemia (ALL), yet optimal patient selection is challenging in the era of rapidly changing modern therapy. Refined molecular characterization allows for better risk assessment, sparing low-risk patients from allo-HCT toxicity while identifying those who may benefit from intensified approaches. Measurable residual disease (MRD) has emerged as a powerful predictor of relapse irrespective of treatment strategy, challenging the necessity of transplant in MRD-negative patients. Further, expanded donor options, particularly haploidentical transplantation coupled with reduced intensity conditioning, have extended the applicability of allo-HCT to a broader range of patients. Finally, immunotherapies and targeted treatments are increasingly integrated into both initial and relapsed treatment protocols yielding deep remission and allowing for successful transplant in patients with a history of advanced disease. In this review, we provide an overview of the contemporary role of transplant in adult patients with ALL, focusing on indications for allo-HCT in first remission, optimal sequencing of transplant with novel therapies, and advancements in donor selection and conditioning regimens.

Measurable residual disease (MRD)-testing in haematological cancers: A giant leap forward or sideways?

Measurable residual disease (MRD)-testing is used in many haematological cancers to estimate relapse risk and to direct therapy. Sometimes MRD-test results are used for regulatory approval. However, some people including regulators wrongfully believe results of MRD-testing are highly accurate and of proven efficacy in directing therapy. We review MRD-testing technologies and evaluate the accuracy of MRD-testing for predicting relapse and the strength of evidence supporting efficacy of MRD-guided therapy. We show that at the individual level MRD-test results are often an inaccurate relapse predictor. Also, no convincing data indicate that increasing therapy-intensity based on a positive MRD-test reduces relapse risk or improves survival. We caution against adjusting therapy-intensity based solely on results of MRD-testing.

Significance of Measurable Residual Disease in Adult Philadelphia Chromosome-Positive ALL: A GRAAPH-2014 Study

PURPOSE

BCR::ABL1 quantification is widely regarded as the standard for monitoring measurable residual disease (MRD) in Philadelphia chromosome-positive (Ph+) ALL. However, recent evidence of BCR::ABL1 multilineage involvement questions the significance of BCR::ABL1 MRD. We aimed to define the prognostic role of MRD as assessed by BCR::ABL1 or lymphoid-specific immunoglobulin/T-cell receptor (IG/TR) gene markers.

PATIENTS AND METHODS

We conducted BCR::ABL1 and IG/TR quantification after each treatment cycle in 264 patients treated in the GRAAPH-2014 trial, which used four cycles of reduced-intensity chemotherapy with nilotinib, followed by hematopoietic stem-cell transplantation (HSCT).

RESULTS

Comparing BCR::ABL1 and IG/TR MRD revealed residual BCR::ABL1-positive non-ALL cells in 98 (43%) of 228 patients, defining multilineage Ph+ ALL. Despite poorer BCR::ABL1 responses, patients with multilineage Ph+ ALL had similar disease-free survival (DFS; hazard ratio [HR], 0.83 [95% CI, 0.49 to 1.41]; P = .50). Although BCR::ABL1 response failed to predict outcomes, IG/TR positivity (≥0.01%) was strongly associated with lower DFS (after cycle 2, HR, 2.49 [95% CI, 1.40 to 4.40]; P = .002; after cycle 4, HR, 4.13 [95% CI, 1.82 to 9.38]; P = .001). In multivariable analysis, both IG/TR positivity after cycle 2 and initial WBC count ≥30 × 109/L predicted poorer DFS, enabling to define a high-risk group having a 4-year DFS of 56.5% compared with 87.6% (HR, 3.72 [95% CI, 1.93 to 7.15]; P < .001). Moreover, allogeneic HSCT significantly improved DFS in the high-risk group (HR, 0.33 [95% CI, 0.18 to 0.60]; P < .001), whereas the standard-risk group had favorable outcomes regardless of allogeneic HSCT.

CONCLUSION

Our findings challenge the significance of BCR::ABL1 monitoring in adult Ph+ ALL and demonstrate the prognostic role of IG/TR MRD. This study provides a framework for using MRD to guide treatment strategies in adults with Ph+ ALL.

Multilineage involvement in KMT2A-rearranged B acute lymphoblastic leukaemia: cell-of-origin, biology, and clinical implications

AIMS

B lymphoblastic leukaemia/lymphoma (B-ALL) is thought to originate from Pro/Pre-B cells and the genetic aberrations largely reside in lymphoid-committed cells. A recent study demonstrated that a proportion of paediatric B-ALL patients have BCR::ABL1 fusion in myeloid cells, suggesting a chronic myeloid leukaemia (CML)-like biology in this peculiar subset of B-ALL, although it is not entirely clear if the CD19-negative precursor compartment is a source of the myeloid cells. Moreover, the observation has not yet been extended to other fusion-driven B-ALLs.

METHODS AND RESULTS

In this study we investigated a cohort of KMT2A-rearranged B-ALL patients with a comparison to BCR::ABL1-rearranged B-ALL by performing cell sorting via flow cytometry followed by FISH (fluorescence in situ hybridization) analysis on each of the sorted populations. In addition, RNA sequencing was performed on one of the sorted populations. These analyses showed that (1) multilineage involvement was present in 53% of BCR::ABL1 and 36% of KMT2A-rearranged B-ALL regardless of age, (2) multilineage involvement created pitfalls for residual disease monitoring, and (3) HSPC transcriptome signatures were upregulated in KMT2A-rearranged B-ALL with multilineage involvement.

CONCLUSIONS

In summary, multilineage involvement is common in both BCR::ABL1-rearranged and KMT2A-rearranged B-ALL, which should be taken into consideration when interpreting the disease burden during the clinical course.

Acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) is a haematological malignancy characterized by the uncontrolled proliferation of immature lymphoid cells. Over past decades, significant progress has been made in understanding the biology of ALL, resulting in remarkable improvements in its diagnosis, treatment and monitoring. Since the advent of chemotherapy, ALL has been the platform to test for innovative approaches applicable to cancer in general. For example, the advent of omics medicine has led to a deeper understanding of the molecular and genetic features that underpin ALL. Innovations in genomic profiling techniques have identified specific genetic alterations and mutations that drive ALL, inspiring new therapies. Targeted agents, such as tyrosine kinase inhibitors and immunotherapies, have shown promising results in subgroups of patients while minimizing adverse effects. Furthermore, the development of chimeric antigen receptor T cell therapy represents a breakthrough in ALL treatment, resulting in remarkable responses and potential long-term remissions. Advances are not limited to treatment modalities alone. Measurable residual disease monitoring and ex vivo drug response profiling screening have provided earlier detection of disease relapse and identification of exceptional responders, enabling clinicians to adjust treatment strategies for individual patients. Decades of supportive and prophylactic care have improved the management of treatment-related complications, enhancing the quality of life for patients with ALL.