Mika T, Thomson J, Nilius-Eliliwi V, et al. Quantification of Cell-Free DNA for the Analysis of CD19-CAR-T Cells During Lymphoma Treatment. Molecular Therapy: Methods & Clinical Development. 2021; 23: 539 (doi: 10.1016/j.omtm.2021.10.009).
Researchers in Germany have demonstrated the viability of using cell-free DNA (cfDNA) to quantify chimeric antigen receptor (CAR)-T cells during immunotherapy, which demands sufficient expansion of CAR-T effector cells in order to perform. Instead of the usual flow cytometry or qPCR techniques, the team tested blood samples for CAR-T cells utilizing a digital-droplet PCR (ddPCR) assay. The samples were derived from a dozen lymphoma patients undergoing treatment with axicabtagene ciloleucel (axi-cel), an anti-CD19 CAR-T cell intervention. The experiment suggests that ddPCR reliably detects and quantifies CAR-T cell-derived cfDNA (cfCAR-DNA) in this patient population. Although relative quantification of CAR-T cells compared with a reference gene yielded similar results for both treatment responders and non-responders, investigators saw much greater promise for the approach when applied in a patient-specific context. In those cases, analysis of cfCAR-DNA and reference cfDNA offered insight into active lymphoma killing and response to CAR-T therapy, suggesting it potentially could be used as a clinical decision-making tool for lymphoma patients. The study authors say their findings point to a need for additional research into the potential role of cfDNA in CAR-T cell therapy.