Assessment of acute myeloid leukemia molecular measurable residual disease testing in an interlaboratory study

Molecular measurable residual disease monitoring and transplant indications in NPM1 mutated acute myeloid leukemia

NPM1 mutated acute myeloid leukemia (AML) comprises roughly 30% of all AML cases and is mainly classified as favorable or intermediate-risk according to the European Leukemia Net stratification. Some patients, however, either have a poor response to initial intensive chemotherapy or ultimately relapse. NPM1 mutations are common, generally stable at early relapse and AML specific, features which make them ideal targets for measurable residual disease (MRD) monitoring. MRD monitoring via molecular analysis during the course of treatment can inform the role of allogeneic stem cell transplantation (HCT) in first remission in patients with NPM1 mutated AML with high-risk co-occurring mutations, particularly FLT3-ITD, and in favorable risk patients who do not achieve defined molecular milestones. In this review, we evaluate the prognostic role of MRD monitoring in NPM1 mutated AML and its use as a predictive biomarker to refine risk stratification and inform decision making regarding treatment. We explore the impact of pre-HCT MRD positivity on post-HCT outcomes in this AML subset, and how HCT-related factors such as conditioning intensity may influence this risk.

Measurable residual disease monitoring in AML: Prospects for therapeutic decision-making and new drug development

Measurable residual disease (MRD) is strongly associated with risk of relapse and long-term survival outcomes in patients with acute myeloid leukemia (AML). Apart from its clear prognostic impact, MRD information is also increasingly used to guide therapeutic decision-making, including selection of appropriate patients for stem cell transplant, use of post-transplant maintenance, and candidacy for non-transplant maintenance therapies or MRD-directed clinical trials. While much progress has been made in accurately assessing MRD and understanding its clinical importance, many questions remain about how to optimize MRD testing and guide treatment decisions for individual patients. In this review, we discuss the common methods to assess MRD in AML and the prognostic impact of MRD across common clinical scenarios. We also review emerging and investigational strategies to target MRD and discuss some of the important unanswered questions and challenges in the field.

Molecular MRD is strongly prognostic in patients with NPM1-mutated AML receiving venetoclax-based nonintensive therapy

ABSTRACT

Assessment of measurable residual disease (MRD) by quantitative reverse transcription polymerase chain reaction is strongly prognostic in patients with NPM1-mutated acute myeloid leukemia (AML) treated with intensive chemotherapy; however, there are no data regarding its utility in venetoclax-based nonintensive therapy, despite high efficacy in this genotype. We analyzed the prognostic impact of NPM1 MRD in an international real-world cohort of 76 previously untreated patients with NPM1-mutated AML who achieved complete remission (CR)/CR with incomplete hematological recovery following treatment with venetoclax and hypomethylating agents (HMAs) or low-dose cytarabine (LDAC). A total of 44 patients (58%) achieved bone marrow (BM) MRD negativity, and a further 14 (18%) achieved a reduction of ≥4 log10 from baseline as their best response, with no difference between HMAs and LDAC. The cumulative rates of BM MRD negativity by the end of cycles 2, 4, and 6 were 25%, 47%, and 50%, respectively. Patients achieving BM MRD negativity by the end of cycle 4 had 2-year overall of 84% compared with 46% if MRD was positive. On multivariable analyses, MRD negativity was the strongest prognostic factor. A total of 22 patients electively stopped therapy in BM MRD-negative remission after a median of 8 cycles, with 2-year treatment-free remission of 88%. In patients with NPM1-mutated AML attaining remission with venetoclax combination therapies, NPM1 MRD provides valuable prognostic information.

Criteria for Diagnosis and Molecular Monitoring of NPM1-Mutated AML

NPM1-mutated acute myeloid leukemia (AML) represents the largest molecular subgroup of adult AML. NPM1-mutated AML is recognizable by molecular techniques and immunohistochemistry, which, when combined, can solve difficult diagnostic problems (including identification of myeloid sarcoma and NPM1 mutations outside exon 12). According to updated 2022 European LeukemiaNet (ELN) guidelines, determining the mutational status of NPM1 (and FLT3) is a mandatory step for the genetic-based risk stratification of AML. Monitoring of measurable residual disease (MRD) by qRT-PCR, combined with ELN risk stratification, can guide therapeutic decisions at the post-remission stage. Here, we review the criteria for appropriate diagnosis and molecular monitoring of NPM1-mutated AML.

SIGNIFICANCE

NPM1-mutated AML represents a distinct entity in the 2022 International Consensus Classification and 5th edition of World Health Organization classifications of myeloid neoplasms. The correct diagnosis of NPM1-mutated AML and its distinction from other AML entities is extremely important because it has clinical implications for the management of AML patients, such as genetic-based risk stratification according to 2022 ELN. Monitoring of MRD by qRT-PCR, combined with ELN risk stratification, can guide therapeutic decisions at the post-remission stage, e.g., whether or not to perform allogeneic hematopoietic stem cell transplantation.