Elizabeth D. Lightbody, PhD, Dana-Farber Cancer Institute, Boston, MA, discusses the value of investigating circulating tumor cells (CTCs) in patients with multiple myeloma. CTCs are present at all stages of the myeloma disease continuum, and CTC levels increase with disease progression. Dr Lightbody discusses some research in which single-cell RNA sequencing was performed on a subset of patients and healthy donors to analyze CTC profiles, and the value of using CTCs as a biomarker of disease. This interview took place at the American Association for Cancer Research Annual Meeting in New Orleans, LA.