Association of hematologic response and assay sensitivity on the prognostic impact of measurable residual disease in acute myeloid leukemia: a systematic review and meta-analysis

Limited efficacy of 3 + 7 plus gemtuzumab ozogamycin in newly diagnosed fit intermediate genetic risk acute myeloid leukemia patients

BACKGROUND

Gemtuzumab-ozogamycin (GO) is approved in combination with high-dose chemotherapy for treatment-naïve low- and intermediate-risk acute myeloid leukemia (AML).

AIMS

In this retrospective real-life multicenter study, we reported efficacy and safety of GO plus high-dose chemotherapy in newly diagnosed AML patients.

METHODS AND RESULTS

A total of 31 fit low- and intermediate-risk AML patients treated with GO-based regimens were retrospectively included in this real-life multicenter study, and results were compared with a control cohort treated with 3 + 7 alone. Complete remission (CR) rate after induction was 77%, and most responders (45%) underwent two GO-based consolidation, and minimal residual disease (MRD) negativity was observed in 17 cases (55%) after the end of consolidation. Low genetic risk was associated with increased CR rate compared with intermediate-risk AML (88% vs. 33%; p < .001), as well as prolonged overall survival (OS; hazard ratio, 0.16; 95% confidential interval, 0.02-0.89; p < .001). GO addition resulted in a survival benefit for low-risk AML (median OS not reached vs. 25 months; p = .19) while not for intermediate-risk subjects (10 vs. 13 months; p = .92), compared with the control group. Moreover, GO-treated patients experienced fever of unknown origin or sepsis in 42% or 36% of cases, respectively, with one death during induction due to septic shock, with similar rates compared with the control group (p = .3480 and p = .5297, respectively). No cases of veno-occlusive disease after allogeneic transplantation were observed.

CONCLUSIONS

Our real-life multicenter study confirmed GO-based treatment efficacy with high MRD negativity rates in fit newly diagnosed AML patients, especially in those with low genetic risk and core binding factor, while limited benefits were observed in intermediate-risk AML. However, further validation on larger prospective cohorts is required.

Minimal Residual Disease in Acute Myeloid Leukemia: Old and New Concepts

Minimal residual disease (MRD) is of major importance in onco-hematology, particularly in acute myeloid leukemia (AML). MRD measures the amount of leukemia cells remaining in a patient after treatment, and is an essential tool for disease monitoring, relapse prognosis, and guiding treatment decisions. Patients with a negative MRD tend to have superior disease-free and overall survival rates. Considerable effort has been made to standardize MRD practices. A variety of techniques, including flow cytometry and molecular methods, are used to assess MRD, each with distinct strengths and weaknesses. MRD is recognized not only as a predictive biomarker, but also as a prognostic tool and marker of treatment efficacy. Expected advances in MRD assessment encompass molecular techniques such as NGS and digital PCR, as well as optimization strategies such as unsupervised flow cytometry analysis and leukemic stem cell monitoring. At present, there is no perfect method for measuring MRD, and significant advances are expected in the future to fully integrate MRD assessment into the management of AML patients.

Quantification of measurable residual disease using duplex sequencing in adults with acute myeloid leukemia

The presence of measurable residual disease (MRD) is strongly associated with treatment outcomes in acute myeloid leukemia (AML). Despite the correlation with clinical outcomes, MRD assessment has yet to be standardized or routinely incorporated into clinical trials and discrepancies have been observed between different techniques for MRD assessment. In 62 patients with AML, aged 18-60 years, in first complete remission after intensive induction therapy on the randomized phase III SWOG-S0106 clinical trial (clinicaltrials gov. Identifier: NCT00085709), MRD detection by centralized, high-quality multiparametric flow cytometry was compared with a 29-gene panel utilizing duplex sequencing (DS), an ultrasensitive next-generation sequencing method that generates double-stranded consensus sequences to reduce false positive errors. MRD as defined by DS was observed in 22 (35%) patients and was strongly associated with higher rates of relapse (68% vs. 13%; hazard ratio [HR] =8.8; 95% confidence interval [CI]: 3.2-24.5; P<0.001) and decreased survival (32% vs. 82%; HR=5.6; 95% CI: 2.3-13.8; P<0.001) at 5 years. DS MRD strongly outperformed multiparametric flow cytometry MRD, which was observed in ten (16%) patients and marginally associated with higher rates of relapse (50% vs. 30%; HR=2.4; 95% CI: 0.9-6.7; P=0.087) and decreased survival (40% vs. 68%; HR=2.5; 95% CI: 1.0-6.3; P=0.059) at 5 years. Furthermore, the prognostic significance of DS MRD status at the time of remission for subsequent relapse was similar on both randomized arms of the trial. These findings suggest that next-generation sequencing-based AML MRD testing is a powerful tool that could be developed for use in patient management and for early anti-leukemic treatment assessment in clinical trials.

Measurable residual disease monitoring in patients with acute myeloid leukemia treated with lower-intensity therapy: Roadmap from an ELN-DAVID expert panel

With the availability of effective targeted agents, significant changes have occurred in the management of patients with acute myeloid leukemia (AML) over the past several years, particularly for those considered unfit for intensive chemotherapy. While testing for measurable residual disease (MRD) is now routinely performed in patients treated with intensive chemotherapy to refine prognosis and, possibly, inform treatment decision-making, its value in the context of lower-intensity regimens is unclear. As such regimens have gained in popularity and can be associated with higher response rates, the need to better define the role of MRD assessment and the appropriate time points and assays used for this purpose has increased. This report outlines a roadmap for MRD testing in patients with AML treated with lower-intensity regimens. Experts from the European LeukemiaNet (ELN)-DAVID AML MRD working group reviewed all available data to propose a framework for MRD testing in future trials and clinical practice. A Delphi poll served to optimize consensus. Establishment of uniform standards for MRD assessments in lower-intensity regimens used in treating patients with AML is clinically relevant and important for optimizing testing and, ultimately, improving treatment outcomes of these patients.

Phase 1/2 study of sorafenib added to cladribine, high-dose cytarabine, G-CSF, and mitoxantrone in untreated AML

The multikinase inhibitor sorafenib improves event-free survival (EFS) when used with 7 + 3 in adults with newly-diagnosed acute myeloid leukemia (AML), irrespective of the FLT3-mutation status. Here, we evaluated adding sorafenib to cladribine, high-dose cytarabine, granulocyte colony-stimulating factor, and mitoxantrone (CLAG-M) in a phase 1/2 trial of 81 adults aged ≤60 years with newly diagnosed AML. Forty-six patients were treated in phase 1 with escalating doses of sorafenib and mitoxantrone. No maximum tolerated dose was reached, and a regimen including mitoxantrone 18 mg/m2 per day and sorafenib 400 mg twice daily was declared the recommended phase 2 dose (RP2D). Among 41 patients treated at RP2D, a measurable residual disease-negative complete remission (MRD- CR) rate of 83% was obtained. Four-week mortality was 2%. One-year overall survival (OS) and EFS were 80% and 76%, without differences in MRD- CR rates, OS, or EFS between patients with or without FLT3-mutated disease. Comparing outcomes using CLAG-M/sorafenib with those of a matched cohort of 76 patients treated with CLAG-M alone, multivariable-adjusted survival estimates were improved for 41 patients receiving CLAG-M/sorafenib at RP2D (OS: hazard ratio,0.24 [95% confidence interval, 0.07-0.82]; P = .023; EFS: hazard ratio, 0.16 [95% confidence interval, 0.05-0.53]; P = .003). Benefit was limited to patients with intermediate-risk disease (univariate analysis: P = .01 for OS; P = .02 for EFS). These data suggest that CLAG-M/sorafenib is safe and improves OS and EFS relative to CLAG-M alone, with benefits primarily in patients with intermediate-risk disease. The trial was registered at www.clinicaltrials.gov as #NCT02728050.

Persistent IDH mutations are not associated with increased relapse or death in patients with IDH-mutated acute myeloid leukemia undergoing allogeneic hematopoietic cell transplant with post-transplant cyclophosphamide

The presence of measurable residual disease (MRD) prior to an allogeneic hematopoietic transplant (alloHCT) in Acute Myeloid Leukemia (AML) has been shown to be associated with an increased risk of post-transplant relapse. Since the Isocitrate Dehydrogenase genes (IDH1/2) are mutated in a considerable proportion of patients with AML, we studied if these mutations would serve as useful targets for MRD. Fifty-five IDH-mutated AML patients undergoing non-myeloablative alloHCT with post-transplant cyclophosphamide at a single center were sequenced at baseline using a multi-gene panel followed by targeted testing for persistent IDH mutations at the pre- and post-alloHCT timepoints by digital droplet PCR or error-corrected next generation sequencing. The cohort included patients who had been treated with IDH inhibitors pre- and post-transplant (20% and 17% for IDH1 and 38% and 28% for IDH2). Overall, 55% of patients analyzed had detectable IDH mutations during complete remission prior to alloHCT. However, there were no statistically significant differences in overall survival (OS), relapse-free survival (RFS), and cumulative incidence of relapse (CIR) at 3 years between patients who tested positive or negative for a persistent IDH mutation during remission (OS: IDH1 p=1, IDH2 p=0.87; RFS: IDH1 p=0.71, IDH2 p= 0.78; CIR: IDH1 p=0.92, IDH2 p=0.97). There was also no difference in the prevalence of persistent IDH mutation between patients who did and did not receive an IDH inhibitor (p=0.59). Mutational profiling of available relapse samples showed that 8 out of 9 patients still exhibited the original IDH mutation, indicating that the IDH mutations remained stable through the course of the disease. This study demonstrates that persistent IDH mutations during remission is not associated with inferior clinical outcomes after alloHCT in patients with AML.

Measurable residual disease in patients undergoing allogeneic transplant for acute myeloid leukemia

The most common indication for allogeneic hematopoietic cell transplant (alloHCT) is maintenance of remission after initial treatment for patients with acute myeloid leukemia (AML). Loss of remission, relapse, remains however the most frequent cause of alloHCT failure. There is strong evidence that detectable persistent disease burden ("measurable residual disease", MRD) in patients with AML in remission prior to alloHCT is associated with increased risk of post-transplant relapse. MRD status as a summative assessment of response to pre-transplant therapy may allow superior patient-personalized risk stratification compared with models solely incorporating pre-treatment variables. An optimal methodology for AML MRD detection has not yet been established, but molecular methods such as DNA-sequencing may have additional prognostic utility compared to current approaches. There is growing evidence that intervention on AML MRD positivity may improve post-transplant outcomes. New initiatives will generate actionable data on the clinical utility of AML MRD testing for patients undergoing alloHCT.

Novel Tools for Diagnosis and Monitoring of AML

In recent years, major advances in the understanding of acute myeloid leukemia (AML) pathogenesis, together with technological progress, have led us into a new era in the diagnosis and follow-up of patients with AML. A combination of immunophenotyping, cytogenetic and molecular studies are required for AML diagnosis, including the use of next-generation sequencing (NGS) gene panels to screen all genetic alterations with diagnostic, prognostic and/or therapeutic value. Regarding AML monitoring, multiparametric flow cytometry and quantitative PCR/RT-PCR are currently the most implemented methodologies for measurable residual disease (MRD) evaluation. Given the limitations of these techniques, there is an urgent need to incorporate new tools for MRD monitoring, such as NGS and digital PCR. This review aims to provide an overview of the different technologies used for AML diagnosis and MRD monitoring and to highlight the limitations and challenges of current versus emerging tools.

Quantification of measurable residual disease using duplex sequencing in adults with acute myeloid leukemia

The presence of measurable residual disease (MRD) is strongly associated with treatment outcomes in acute myeloid leukemia (AML). Despite the correlation with clinical outcomes, MRD assessment has yet to be standardized or routinely incorporated into clinical trials. Discrepancies have been observed between different techniques for MRD assessment and there remains a need to compare centralized, high-quality multiparametric flow cytometry (MFC) and ultrasensitive next-generation sequencing (NGS) in AML patients with diverse mutational profiles. In 62 patients with AML, aged 18-60, in first complete remission after intensive induction therapy on the randomized phase 3 SWOG-S0106 clinical trial, MRD detection by MFC was compared with a 29 gene panel utilizing duplex sequencing (DS), an NGS method that generates double-stranded consensus sequences to reduce false positive errors. Using DS, detection of a persistent mutation utilizing defined criteria was seen in 22 (35%) patients and was strongly associated with higher rates of relapse (68% vs 13% at year 5; HR, 8.8; 95% CI, 3.2-24.5; P<0.001) and decreased survival (32% vs 82% at year 5; HR, 5.6; 95% CI, 2.3-13.8; P<0.001). MRD as defined by DS strongly outperformed MFC, which was observed in 10 (16%) patients and marginally associated with higher rates of relapse (50% vs 30% at year 5; HR, 2.4; 95% CI, 0.9-6.7; P=0.087) and decreased survival (40% vs 68% at year 5; HR, 2.5; 95% CI, 1.0-6.3; P=0.059). Furthermore, the prognostic significance of DS MRD status at the time of remission was similar on both randomized arms of the trial, predicting S0106 clinical trial outcomes. These findings suggest that DS is a powerful tool that could be used in patient management and for early treatment assessment in clinical trials.

DNA Sequencing to Detect Residual Disease in Adults With Acute Myeloid Leukemia Prior to Hematopoietic Cell Transplant

Importance

Preventing relapse for adults with acute myeloid leukemia (AML) in first remission is the most common indication for allogeneic hematopoietic cell transplant. The presence of AML measurable residual disease (MRD) has been associated with higher relapse rates, but testing is not standardized.

Objective

To determine whether DNA sequencing to identify residual variants in the blood of adults with AML in first remission before allogeneic hematopoietic cell transplant identifies patients at increased risk of relapse and poorer overall survival compared with those without these DNA variants.

Design, Setting, and Participants

In this retrospective observational study, DNA sequencing was performed on pretransplant blood from patients aged 18 years or older who had undergone their first allogeneic hematopoietic cell transplant during first remission for AML associated with variants in FLT3, NPM1, IDH1, IDH2, or KIT at 1 of 111 treatment sites from 2013 through 2019. Clinical data were collected, through May 2022, by the Center for International Blood and Marrow Transplant Research.

Exposure

Centralized DNA sequencing of banked pretransplant remission blood samples.

Main Outcomes and Measures

The primary outcomes were overall survival and relapse. Day of transplant was considered day 0. Hazard ratios were reported using Cox proportional hazards regression models.

Results

Of 1075 patients tested, 822 had FLT3 internal tandem duplication (FLT3-ITD) and/or NPM1 mutated AML (median age, 57.1 years, 54% female). Among 371 patients in the discovery cohort, the persistence of NPM1 and/or FLT3-ITD variants in the blood of 64 patients (17.3%) in remission before undergoing transplant was associated with worse outcomes after transplant (2013-2017). Similarly, of the 451 patients in the validation cohort who had undergone transplant in 2018-2019, 78 patients (17.3%) with residual NPM1 and/or FLT3-ITD variants had higher rates of relapse at 3 years (68% vs 21%; difference, 47% [95% CI, 26% to 69%]; HR, 4.32 [95% CI, 2.98 to 6.26]; P < .001) and decreased survival at 3 years (39% vs 63%; difference, -24% [2-sided 95% CI, -39% to -9%]; HR, 2.43 [95% CI, 1.71 to 3.45]; P < .001).

Conclusions and Relevance

Among patients with acute myeloid leukemia in first remission prior to allogeneic hematopoietic cell transplant, the persistence of FLT3 internal tandem duplication or NPM1 variants in the blood at an allele fraction of 0.01% or higher was associated with increased relapse and worse survival compared with those without these variants. Further study is needed to determine whether routine DNA-sequencing testing for residual variants can improve outcomes for patients with acute myeloid leukemia.

Targeting Measurable Residual Disease (MRD) in Acute Myeloid Leukemia (AML): Moving beyond Prognostication

Measurable residual disease (MRD) assessment in acute myeloid leukemia (AML) has an established role in disease prognostication, particularly in guiding decisions for hematopoietic cell transplantation in first remission. Serial MRD assessment is now routinely recommended in the evaluation of treatment response and monitoring in AML by the European LeukemiaNet. The key question remains, however, if MRD in AML is clinically actionable or "does MRD merely portend fate"? With a series of new drug approvals since 2017, we now have more targeted and less toxic therapeutic options for the potential application of MRD-directed therapy. Recent approval of NPM1 MRD as a regulatory endpoint is also foreseen to drastically transform the clinical trial landscape such as biomarker-driven adaptive design. In this article, we will review (1) the emerging molecular MRD markers (such as non-DTA mutations, IDH1/2, and FLT3-ITD); (2) the impact of novel therapeutics on MRD endpoints; and (3) how MRD might be used as a predictive biomarker to guide therapy in AML beyond its prognostic role, which is the focus of two large collaborative trials: AMLM26 INTERCEPT (ACTRN12621000439842) and MyeloMATCH (NCT05564390).