Have we been qualifying measurable residual disease correctly?

Minimal residual disease monitoring in acute myeloid leukemia: Focus on MFC-MRD and treatment guidance for elderly patients

Acute myeloid leukemia (AML) is distinguished by clonal growth of myeloid precursor cells, which impairs normal hematopoiesis. Minimal residual disease (MRD) refers to the residual leukemia cells that persist after chemotherapy. Patients who test positive for MRD have a higher likelihood of experiencing a recurrence, regardless of the specific chemotherapy approach used. Multi-parameter flow cytometry (MFC), polymerase chain reaction (PCR), and next-generation sequencing (NGS) are commonly employed techniques for identifying MRD. In the context of AML, patients are frequently monitored for measurable residual disease via multi-parameter flow cytometry (MFC-MRD). In order to explore recent advancements in AML and MRD diagnosis, an extensive search of the PubMed database was conducted, focusing on relevant research in the past 20 years. This review aims to examine various MRD monitoring methods, the optimal time points for assessment, as well as different specimen types used. Additionally, it underscores the significance of MFC-MRD assessment in guiding the treatment of elderly AML.

Longitudinal genetically detectable minimal residual disease by fluorescence in situ hybridization confers a poor prognosis in myeloma

Background

Deeper depth of response (DpR) after induction therapy, especially gain of negative minimal residual disease (MRD), has been linked to prolonged survival in multiple myeloma (MM). However, flow-MRD examination focuses on the numbers but not on the biological characteristics of residual plasma cells (PCs).

Objectives

To explore whether the genetic features of residual tumor cells affect the survival time of patients with MM.

Design

A retrospective cohort study.

Methods

We investigated the clonality of cytogenetic abnormalities (CAs) of the residual PCs using interphase fluorescence in situ hybridization (iFISH) in the National Longitudinal Cohort of Hematological Diseases in China (NCT04645199). Here, a longitudinal cohort of 269 patients with patient-paired diagnostic and post-induction iFISH results was analyzed.

Results

Persistent CAs after induction therapy were detected in about half of the patients (118/269, 43%), and patients with undetectable CAs showed significantly improved survival compared with those with genetically detectable MRD [median progression-free survival (mPFS): 59.7 versus 35.7 months, p < 0.001; median overall survival (mOS): 97.1 versus 68.8 months, p = 0.011]. In addition, different patterns of therapy-induced clonal evolution were observed by comparing the clonal structure of residual PCs with paired baseline samples. Patients who maintained at a high risk during follow-up had the worst survival (mPFS: 30.5 months; mOS: 54.4 months), while those who returned to lower risk or had iFISH- at both time points had the best survival (mPFS: 62.0 months, mOS: not reached).

Conclusion

These findings highlighted the prognostic value of genetic testing in residual tumor cells, which may provide a deep understanding of clonal evolution and guide clinical therapeutic strategies.