Impact of clinical utility of MRD assessment with different techniques on survival in acute B lymphoblastic leukemia

Highly sensitive single tube B-lymphoblastic leukemia/lymphoma minimal/measurable residual disease test robust to surface antigen directed therapy

BACKGROUND

Measurement of minimal/measurable residual disease (MRD) in B-lymphoblastic leukemia/lymphoma (B-ALL) has become a routine clinical evaluation tool and remains the strongest predictor of treatment outcome. In recent years, new targeted anti-CD19 and anti-CD22 antibody-based and cellular therapies have revolutionized the treatment of the high-risk B-ALL. The new treatments raise challenges for diagnostic flow cytometry, which relies on the presence of specific surface antigens to identify the population of interest. So far, reported flow cytometry-based assays are developed to either achieve a deeper MRD level or to accommodate the loss of surface antigens post-target therapies, but not both.

METHODS

We developed a single tube flow cytometry assay (14-color-16-parameters). The method was validated using 94 clinical samples as well as spike-in and replicate experiments.

RESULTS

The assay was well suited for monitoring response to targeted therapies and reached a sensitivity below 10-5 with acceptable precision (coefficient of variation < 20%), accuracy, and interobserver variability (κ = 1).

CONCLUSIONS

The assay allows for sensitive disease detection of B-ALL MRD independent of CD19 and CD22 expression and allows uniform analysis of samples regardless of anti-CD19 and CD22 therapy.

Immunophenotypic measurable residual disease monitoring in adult acute lymphoblastic leukemia patients undergoing allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) offers a survival benefit to adult patients affected by acute lymphoblastic leukemia (ALL). However, to avoid an overt disease relapse, patients with pre or post transplant persistence or occurrence of measurable residual disease (MRD) may require cellular or pharmacological interventions with eventual side effects. While the significance of multiparametric flow cytometry (MFC) in the guidance of ALL treatment in both adult and pediatric patients is undebated, fewer data are available regarding the impact of MRD monitoring, as assessed by MFC analysis, in the allo-HSCT settings. Aim of this article is to summarize and discuss currently available information on the role of MFC detection of MRD in adult ALL patients undergoing allo-HSCT. The significance of MFC-based MRD according to sensitivity level, timing, and in relation to molecular techniques of MRD and chimerism assessment will be also discussed.

[Clinical significance of minimal residual disease in B-lineage acute lymphoblastic leukemia pediatric patients with different fusion gene backgrounds]

OBJECTIVE

To study the clinical significance of minimal residual disease (MRD) in B-lineage acute lymphoblastic leukemia (B-ALL) pediatric patients with different fusion gene backgrounds.

METHODS

A retrospective analysis was performed on the medical data of 441 B-ALL children who were treated from January 2008 to April 2015. Among the 441 children, 336 had negative fusion gene, 79 had positive ETV6-RUNX1 fusion gene, and 26 had positive E2A-PBX1 fusion gene. Flow cytometry was used to detect MRD, and the influence of MRD on day 15 (TP1), day 33 (TP2), and week 12 (TP3) of induction therapy on prognosis was analyzed.

RESULTS

In patients with negative fusion gene, the positive MRD group had significantly lower overall survival (OS) rate and event-free survival (EFS) rate (P < 0.05) and significantly higher recurrence rate and mortality rate at TP1, TP2, and TP3, compared with the negative MRD group (P < 0.05). In patients with positive ETV6-RUNX1, the positive MRD group had significantly lower OS and EFS rates (P < 0.05) and significantly higher recurrence rate and mortality rate (P < 0.05) than the negative MRD group only at TP1. In patients with positive E2A-PBX1, there were no significant differences in the OS rate, recurrence rate, and mortality rate between the positive and negative MRD groups at TP1, TP2, and TP3 (P > 0.05).

CONCLUSIONS

MRD has the most definite prognostic significance in pediatric B-ALL patients with negative fusion gene, while it has unsatisfactory prognostic significance in those with positive ETV6-RUNX1 or positive E2A-PBX1.

Consolidative allogeneic hematopoietic stem cell transplantation after chimeric antigen receptor T-cell therapy for relapsed/refractory B-cell acute lymphoblastic leukemia: who? When? Why?

Although anti-CD19 chimeric antigen receptor (CAR) T-cell therapy shows good efficacy in patients with relapsed/refractory B-cell acute lymphoblastic leukemia (r/r B-ALL), it fails to improve long-term leukemia-free survival (LFS). Allogeneic hematopoietic stem cell transplantation (allo-HSCT) after CAR T-cell therapy has emerged as a promising strategy to prolong LFS. Nevertheless, which patients are likely to benefit from consolidative allo-HSCT, as well as the optimal therapeutic window, remain to be explored. Recent clinical data indicate that patients with complex karyotypes, adverse genes, and high pre-infusion minimal residual disease (MRD) by flow cytometry in the bone marrow, were at high risk of relapse after CAR T-cell therapy. High pre-lymphodepletion lactate dehydrogenase, low pre-lymphodepletion platelet count, absence of fludarabine in lymphodepletion, persistent leukemic sequence by high throughput sequencing in bone marrow after CAR T-cell infusion, and early loss of CAR T cells have also been linked to relapse after CAR T-cell therapy. In patients having these risk factors, consolidative allo-HSCT after CAR T-cell therapy may prolong LFS. Allo-HSCT provides optimal clinical benefit in patients with MRD-negative complete remission, typically within three months after CAR T-cell therapy. Herein, we summarize the clinical data on consolidative allo-HSCT after anti-CD19 CAR T-cell therapy, as well as the potential factors associated with allo-HSCT benefit. We also discuss the optimal therapeutic window and regimen of consolidative allo-HSCT. Finally, and most importantly, we provide recommendations for the assessment and management of r/r B-ALL patients undergoing anti-CD19 CAR T-cell therapy.

Dynamic prediction of relapse in patients with acute leukemias after allogeneic transplantation: Joint model for minimal residual disease

INTRODUCTION

Relapse remains the leading cause of treatment failure after allogeneic hematopoietic stem cell transplantation (alloHSCT) in leukemia. Numerous investigations have demonstrated that minimal residual disease (MRD) before or after alloHSCT is prognostic of relapse risk. These MRD data were collected at specific checkpoints and could not dynamically predict the relapse risk after alloHSCT, which needs serial monitoring.

METHODS

In the present study, we retrospectively analyzed MRD measured with multi-parameter flow cytometry in 207 acute myeloid leukemia (AML) patients (acute promyelocytic leukemia excluded), and 124 acute B lymphoblastic leukemia (ALL) patients. A three-step method based on joint model was used to build a relapse risk prediction model.

RESULTS

The 3-year overall survival and relapse-free survival rates of the entire cohort were 67.1% ± 2.8% and 61.6% ± 2.8%, respectively. The model included disease status before alloHSCT, acute and chronic graft-versus-host disease, and serial MRD data. The time-dependent receiver operating characteristics was used to evaluate the ability of the model. It fitted well with actual incidence of relapse. The serial MRD data collected after alloHSCT had better discrimination capabilities for recurrence prediction with the area under the curve from 0.67 to 0.91 (AML: 0.66-0.89; ALL: 0.70-0.96).

CONCLUSION

The joint model was able to dynamically predict relapse-free probability after alloHSCT, which would be a useful tool to provide important information to guide decision-making in the clinic and facilitate the individualized therapy.

[Efficacy of Hyper-CVAD/MA and CHALL-01 regimens in the treatment of Philadelphia chromosome-positive adult acute lymphoblastic leukemia patients under 60 years old]

Objective: To compare the difference of efficacy between traditional Hyper-CVAD/MA regimen and the adolescents inspired chemotherapy regimen, CH ALL-01, in treatment of adult Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL) . Methods: In this study we retrospectively analyzed 158 Ph(+) ALL patients receiving Hyper-CVAD/MA regimen (n=63) or CHALL-01 regimen (n=95) in our center and Changzheng hospital from January 2007 to December 2017, excluding patients with chronic myeloid leukemia in blast crisis. Tyrosine kinase inhibitor (TKI) was administered during induction and consolidation chemotherapy. Patients who underwent hematopoietic stem cell transplantation received TKI as maintenance therapy. Results: Of them, 91.1% (144/158) patients achieved complete remission (CR) after 1-2 courses of induction. CR rate was 90.5% (57/63) for patients in Hyper-CVAD/MA group and 91.6% (87/95) for patients in CHALL-01 group. There was no difference in CR rates between the two groups (χ(2)=0.057, P=0.811) . The last follow-up was June 2018. A cohort of 134 CR patients could be used for further analysis, among them, 53 patients received Hyper-CVAD/MA regimen and other 81 patients received CHALL-01 regimen. The molecular remission rates were significantly higher in CHALL-01 group (complete molecular response: 44.4%vs 22.6%; major molecular response: 9.9% vs 18.9%) (χ(2)=7.216, P=0.027) . For the patients in Hyper-CVAD/MA group, the 4-year overall survival (OS) was 44.81% (95%CI: 30.80%-57.86%) and the 4-year disease free survival (DFS) was 37.95% (95%CI: 24.87%-50.93%) . For patients received CHALL-01 regimen, the 4-year OS was 55.63% (95%CI: 39.07%-69.36%) (P=0.037) and 4 year DFS was 49.06% (95%CI: 34.24%-62.29%) (P=0.015) , while there was no significant difference in 4 year cumulative incidence of relapse (CIR) (P=0.328) or cumulative incidence of nonrelapse mortality (CI-NRM) (P=0.138) . The rate of pulmonary infection was lower in patients received CHALL-01 regimen compared with patients received Hyper-CVAD regimen (43.4% vs 67.9%, χ(2)=7.908, P=0.005) . Conclusions: Outcome with CHALL-01 regimen appeared better than that with the Hyper-CVAD/MA regimen in Ph(+) ALL, which has lower incidence of pulmonary infection, higher molecular remission rate and better OS and DFS.

Approach to the Adult Acute Lymphoblastic Leukemia Patient

During recent decades, understanding of the molecular mechanisms of acute lymphoblastic leukemia (ALL) has improved considerably, resulting in better risk stratification of patients and increased survival rates. Age, white blood cell count (WBC), and specific genetic abnormalities are the most important factors that define risk groups for ALL. State-of-the-art diagnosis of ALL requires cytological and cytogenetical analyses, as well as flow cytometry and high-throughput sequencing assays. An important aspect in the diagnostic characterization of patients with ALL is the identification of the Philadelphia (Ph) chromosome, which warrants the addition of tyrosine kinase inhibitors (TKI) to the chemotherapy backbone. Data that support the benefit of hematopoietic stem cell transplantation (HSCT) in high risk patient subsets or in late relapse patients are still questioned and have yet to be determined conclusive. This article presents the newly published data in ALL workup and treatment, putting it into perspective for the attending physician in hematology and oncology.