Genetic interrogation of circulating multiple myeloma cells at single-cell resolution

Abstract

Multiple myeloma (MM) remains an incurable disease, with a treatment-refractory state eventually developing in all patients. Constant clonal evolution and genetic heterogeneity of MM are a likely explanation for the emergence of drug-resistant disease. Monitoring of MM genomic evolution on therapy by serial bone marrow biopsy is unfortunately impractical because it involves an invasive, painful procedure. Here, we describe how non-invasive and highly sensitive isolation and characterization of circulating tumor cells (CTCs) from peripheral blood at single cell resolution recapitulates MM in the bone marrow. We demonstrate that CTCs provide the same genetic information as bone marrow MM cells, and even reveal mutations with greater sensitivity than bone marrow biopsies in some cases. Single CTC RNA sequencing enables classification of MM and quantitative assessment of genes that are relevant for prognosis. We propose that the genomic characterization of CTCs should be included in clinical trials to follow the emergence of resistant subclones after MM therapy.

Minimal residual disease by flow cytometry and allelic‐specific oligonucleotide real‐time quantitative polymerase chain reaction in patients with myeloma receiving lenalidomide maintenance: A pooled analysis

“…5 Moreover, discordances could be attributed to different sensitivity and the different targets analyzed. [32][33][34] We confirmed that MRD negativity is a strong prognostic factor in patients with MM, together with baseline clinical and biologic characteristics (ISS stage, cytogenetic risk, therapy). Moreover, the use of functional whole-body imaging techniques, such as positron emission tomography/computed tomography [PET/CT], has highlighted the problem of spatial heterogeneity, 30 with negative BM analysis results but the presence of skeletal lesions or extramedullary disease.…”

“…Nevertheless, these methods can help to explore the mutational profile and subclonal composition of MM cells rather than detecting MRD because of the potential lack of sensitivity in peripheral blood after treatment. [32][33][34] We confirmed that MRD negativity is a strong prognostic factor in patients with MM, together with baseline clinical and biologic characteristics (ISS stage, cytogenetic risk, therapy). It is noteworthy that MRD-negative patients with high-risk cytogenetics had prolonged PFS (median, not reached by either ASO-RQ-PCR or MFC) versus MRD-positive patients (median, 22.6 months by ASO-RQ-PCR, 15.4 months by MFC).…”

Single‐cell RNA sequencing reveals chemokine self‐feeding of myeloma cells promotes extramedullary metastasis

“…This CXCL12 upregulation may contribute to the initial extramedullary translocation by evasion of CXCR4‐dependent cell retention in bone marrow. Upregulation of another bone marrow retention chemokine, CXCL7, was previously published , further supporting the notion of chemokine auto‐secretion relating to extramedullary translocation in myeloma.…”

Isolation of Circulating Plasma Cells in Multiple Myeloma Using CD138 Antibody-Based Capture in a Microfluidic Device

“…Liquid biopsy could also be used as a screening tool for patients in remission for early detection of recurrence, and it also opens possibilities for performing different assays on the captured cells. A recent study shows, using single-cell sequencing, that that multiple myeloma CTCs are similar to myeloma cells from the bone marrow with respect to their drug-resistance and clonality29; the authors argue that CTC testing should be part of the clinical evaluation for treatment responsivity and disease management as a means to replace the currently invasive bone marrow biopsy protocols. The sensitive detection and isolation of CPCs using microfluidics could address this need for accurate, single-cell diagnostics that go beyond the current standard of care for myeloma patients and potentially eliminate the need for bone marrow biopsies.…”