Testing for minimal residual disease in adults with acute lymphoblastic leukemia in Europe: a clinician survey

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.

Real-world use of blinatumomab in adult patients with B-cell acute lymphoblastic leukemia in clinical practice: results from the NEUF study

This retrospective observational study (NEUF) included adult patients with B-cell acute lymphoblastic leukemia (B-cell ALL) who had received blinatumomab for the treatment of minimal residual disease-positive (MRD+) or relapsed/refractory (R/R) B-cell ALL via an expanded access program (EAP). Patients were eligible if blinatumomab was initiated via the EAP between January 2014 and June 2017. Patients were followed from blinatumomab initiation until death, entry into a clinical trial, the end of follow-up, or the end of the study period (December 31, 2017), whichever occurred first. Of the 249 adult patients included, 109 were MRD+ (83 Philadelphia chromosome-negative [Ph-] and 26 Philadelphia chromosome-positive [Ph+]) and 140 had a diagnosis of R/R B-cell ALL (106 Ph- and 34 Ph+). In the MRD+ group, within the first cycle of blinatumomab treatment, 93% (n = 49/53) of Ph- and 64% (n = 7/11) of Ph+ patients with evaluable MRD achieved an MRD response (MRD <0.01%). Median overall survival (OS) was not reached over a median follow-up time of 18.5 months (Ph-, 18.8 [range: 5.1-34.8] months; Ph+, 16.5 [range: 1.8-31.6] months). In the R/R group, within two cycles of blinatumomab, 51% of Ph- and 41% of Ph+ patients achieved complete hematologic remission (CR/CRh/CRi), and 83% of Ph- and 67% of Ph+ MRD-evaluable patients in CR/CRh/CRi achieved an MRD response. Median (95% confidence interval) OS was 12.2 (7.3-24.2) months in the R/R Ph- subgroup and 16.3 (5.3-not estimated) months in the R/R Ph+ subgroup. This large, real-world data set of adults with B-cell ALL treated with blinatumomab confirms efficacy outcomes from published studies.

Prognostic value of low-level MRD in adult acute lymphoblastic leukemia detected by low- and high-throughput methods

Adult patients with acute lymphoblastic leukemia with low MRD positivity at week 16 form an intermediate-risk group.

NGS improves the risk assignment of patients with MolNE MRD.

Persistence of minimal residual disease (MRD) after induction/consolidation therapy in acute lymphoblastic leukemia is the leading cause of relapse. The GMALL 07/2003 study used MRD detection by real-time quantitative polymerase chain reaction of clonal immune gene rearrangements with 1 × 10⁻⁴ as discriminating cutoff: levels ≥1 × 10⁻⁴ define molecular failure and MRD-negativity with an assay sensitivity of at least 1 × 10⁻⁴ defining complete molecular response. The clinical relevance of MRD results not fitting into these categories is unclear and termed “molecular not evaluable” (MolNE) toward MRD-based treatment decisions. Within the GMALL 07/03 study, 1019 consecutive bone marrow samples after first consolidation were evaluated for MRD. Patients with complete molecular response had significantly better outcome (5-year overall survival [OS] = 85% ± 2%, n = 603; 5-year disease-free survival [DFS] = 73% ± 2%, n = 599) compared with patients with molecular failure (5-year OS = 40% ± 3%, n = 238; 5-year DFS = 29% ± 3%, n = 208), with patients with MolNE in between (5-year OS = 66% ± 4%; 5-year DFS = 52% ± 4%, n = 178). Of MolNE samples reanalyzed using next-generation sequencing (NGS), patients with undetectable NGS-MRD (n = 44; 5-year OS = 88% ± 5%, 5-year DFS = 70% ± 7%) had significantly better outcome than those with positive NGS-MRD (n = 42; 5-year OS = 37% ± 8%; 5-year DFS = 33% ± 8%). MolNE MRD results not just are borderline values with questionable relevance but also form an intermediate-risk group, assignment of which can be further improved by NGS.

Consensus Recommendations for MRD Testing in Adult B-Cell Acute Lymphoblastic Leukemia in Ontario

Measurable (minimal) residual disease (MRD) is an established, key prognostic factor in adult B-cell acute lymphoblastic leukemia (B-ALL), and testing for MRD is known to be an important tool to help guide treatment decisions. The clinical value of MRD testing depends on the accuracy and reliability of results. Currently, there are no Canadian provincial or national guidelines for MRD testing in adult B-ALL, and consistent with the absence of such guidelines, there is no uniform Ontario MRD testing consensus. Moreover, there is great variability in Ontario in MRD testing with respect to where, when, and by which technique, MRD testing is performed, as well as in how the results are interpreted. To address these deficiencies, an expert multidisciplinary working group was convened to define consensus recommendations for improving the provision of such testing. The expert panel recommends that MRD testing should be implemented in a centralized manner to ensure expertise and accuracy in testing for this low volume indication, thereby to provide accurate, reliable results to clinicians and patients. All adult patients with B-ALL should receive MRD testing after induction chemotherapy. Philadelphia chromosome (Ph)-positive patients should have ongoing monitoring of MRD during treatment and thereafter, while samples from Ph-negative B-ALL patients should be tested at least once later during treatment, ideally at 12 to 16 weeks after treatment initiation. In Ph-negative adult B-ALL patients, standardized, ideally centralized, protocols must be used for MRD testing, including both flow cytometry and immunoglobulin (Ig) heavy chain and T-cell receptor (TCR) gene rearrangement analysis. For Ph-positive B-ALL patients, MRD testing using a standardized protocol for reverse transcription real-time quantitative PCR (RT-qPCR) for the BCR-ABL1 gene fusion transcript is recommended, with Ig/TCR gene rearrangement analysis done in parallel likely providing additional clinical information.

Expression of CD304/neuropilin-1 in adult b-cell lymphoblastic leukemia/lymphoma and its utility for the measurable residual disease assessment

INTRODUCTION

Many new markers are being evaluated to increase the sensitivity and applicability of multicolor flow cytometry (MFC)-based measurable residual disease (MRD) monitoring. However, most of the studies are limited to childhood B-cell lymphoblastic leukemia/lymphoma (B-ALL), and reports in adult B-ALL are extremely scarce and limited to small cohorts. We studied the expression of CD304/neuropilin-1 in a large cohort of adult B-ALL patients and evaluated its practical utility in MFC-based MRD analysis.

METHODS

CD304 was studied in blasts from adult B-ALL patients and normal precursor B cells (NPBC) from non-B-ALL bone marrow samples using MFC. CD304 expression intensity and pattern were studied with normalized-mean fluorescent intensity (nMFI) and coefficient of variation of immunofluorescence (CVIF), respectively. MFC-based MRD was performed at end of induction (EOI; day-35), end of consolidation (EOC; day 78-80), and subsequent follow-up (SFU) time points.

RESULTS

CD304 was positive in 120/214(56.07%) and was significantly associated with BCR-ABL1 fusion (P = .001). EOI-MRD and EOC-MRD were positive in 129/214(60.3%) and 50/81(61.72%), respectively. CD304 was positive in a significant percentage of EOI (48%, 62/129) and EOC (52%, 26/50) MRD-positive B-ALL samples. Its expression was retained, lost, and gained in 73.7%, 26.3%, and 11.3% of EOI-MRD and 85.7%, 14.3%, and none of EOC-MRD samples, respectively. Low-level MRD (<0.01%) was detectable in 34 of all (EOI + EOC + SFU = 189) MRD-positive samples, and CD304 was found useful in 50% of these samples.

CONCLUSION

CD304 is commonly expressed in adult B-ALL and clearly distinguish B-ALL blasts from normal precursor B cells. It is a stable MRD marker and distinctly useful in the detection of MFC-based MRD monitoring, especially in high-sensitivity MRD assay.

Monitoring MRD in ALL: Methodologies, technical aspects and optimal time points for measurement

The accurate determination of minimal or measurable residual disease (MRD) during the early months of therapy in acute lymphoblastic leukemia is well established as the most important independent prognostic biomarker, predicting response to combination chemotherapy. Stratification based on MRD maximizes treatment effectiveness while minimizing adverse effects. Allele-specific real-time quantitative PCR of clone-defining immunoglobin/T-cell receptor gene rearrangements in the patients' leukemic clones and/or multiparametric flow cytometric tracking of leukemia-associated immunophenotypes are considered standard of care. Following recent advances in high throughput sequencing (HTS; next generation sequencing), much attention has been devoted to the development of HTS-based MRD assays, which can increase sensitivity; theoretically only limited by the number of cells input into the assay. Knowledge of the methods and limitations of each technology, along with awareness of the sensitivity and specificity of MRD at particular treatment time points is important in interpretation of the MRD value. MRD negativity at pre-established protocol-appropriate time points guides continuance with consolidation/maintenance chemotherapy, whereas positivity leads to a change to a biological therapy such as blinatumomab and intensification of therapy to allogeneic stem cell transplant. Positivity after maintenance may herald impending relapse enabling treatment intervention. MRD has been integral to the introduction of novel agents and cellular therapies into clinical trials and standard of care, but the long-term predictive value of MRD on outcome of novel therapies is not yet established. Integration of somatic genetics with MRD may further improve accurate identification of patients with the lowest and highest risk of relapse.

Management of patients with acute lymphoblastic leukemia in routine clinical practice: Minimal residual disease testing, treatment patterns and clinical outcomes in Belgium, Greece and Switzerland

OBJECTIVES

To describe real-world management and clinical and economic outcomes of patients with B-cell precursor acute lymphoblastic leukemia (ALL) in Belgium, Greece and Switzerland.

METHODS

This descriptive, retrospective medical chart review collected patient-level data in 2018 from adults with ≥1 minimal residual disease (MRD) test during front-line ALL treatment. Data were stratified by MRD status.

RESULTS

Eighty-two patients were included (median age 44 years, 23 % Philadelphia chromosome-positive; MRD-positive: n = 17, MRD-negative: n = 50, MRD result unknown: n = 15). HyperCVAD (32 %) and HOVON (26 %) were the most frequently used front-line treatment protocols; 22 % of patients received stem cell transplantation. Overall, 76 % of ALL patients were hospitalized (mean 1.1 hospitalization/month). Complete hematological response (CRh) occurred in 66/82 patients (80 %). Median relapse-free survival from CRh was 32.7 months (MRD-positive: 11.7 months; MRD-negative: 33.3 months). Median overall survival from diagnosis was 28.9 months (MRD-positive: 15.3 months; MRD-negative: not reached). Most patients (88 %) were MRD tested during induction; testing rates considerably decreased thereafter (39 % during consolidation).

CONCLUSIONS

B-cell precursor ALL represents a clinical burden and impacts healthcare resources; MRD-positive patients have worse prognosis than MRD-negative patients. Efforts should be made to adhere to recommendations for MRD testing in clinical guidelines.

Let's Talk About BiTEs and Other Drugs in the Real-Life Setting for B-Cell Acute Lymphoblastic Leukemia

Background: Therapy for acute lymphoblastic leukemia (ALL) are currently initially efficient, but even if a high percentage of patients have an initial complete remission (CR), most of them relapse. Recent data shows that immunotherapy with either bispecific T-cell engagers (BiTEs) of chimeric antigen receptor (CAR) T cells can eliminate residual chemotherapy-resistant B-ALL cells.

Objective: The objective of the manuscript is to present improvements in the clinical outcome for chemotherapy-resistant ALL in the real-life setting, by describing Romania's experience with bispecific antibodies for B-cell ALL.

Methods: We present the role of novel therapies for relapsed B-cell ALL, including the drugs under investigation in phase I-III clinical trials, as a potential bridge to transplant. Blinatumomab is presented in a critical review, presenting both the advantages of this drug, as well as its limitations.

Results: Bispecific antibodies are discussed, describing the clinical trials that resulted in its approval by the FDA and EMA. The real-life setting for relapsed B-cell ALL is described and we present the patients treated with blinatumomab in Romania.

Conclusion: In the current manuscript, we present blinatumomab as a therapeutic alternative in the bridge-to-transplant setting for refractory or relapsed ALL, to gain a better understanding of the available therapies and evidence-based data for these patients in 2019.

Inhibition of mTORC1/P70S6K pathway by Metformin synergistically sensitizes Acute Myeloid Leukemia to Ara-C

AIMS

Chemo-resistance still was the main obstacle for AML patients, more effective and less toxic forms of therapies were desperately needed. Metformin, a classic hypoglycemic drug for diabetes recently delivered us a new identity that it exerted anti-tumor activity through suppressing mTOR in various tumors. But the anti-tumor effect of metformin in AML was not clear.

METHODS

In this study, we used CCK8 assay and apoptosis assay to determine the anti-leukemia activity of metformin combined with AraC, and explore the mechanism of the joint role of Ara-C/metformin in AML. We finally used xenograft experiment in mice to determine the anti-leukemia effect of Ara-C/metformin in vivo.

KEY FINDINGS

We found that metformin could synergistically sensitize AML cells to Ara-C via inhibiting mTORC1/P70S6K pathway. In vivo experiment also verified metformin in aid of Ara-C caused an obviously synergistic anti-tumor effect.

SIGNIFICANCE

We firstly found the synergistic anti-tumor effect of Ara-C/metformin in AML through inhibiting mTORC1/P70S6K pathway.