Novel assay shows promise for non-invasive detection of PD-L1 on circulating tumor cells

Future Science Group (FSG) today announced the publication of an article in Future Science OA presenting early data from a novel assay for the non-invasive detection of PD-L1 and other biomarkers in patient blood samples.

Response rates to immunotherapies targeting the PD-1 pathway vary, and efforts are ongoing to improve the discovery of those who will and will not benefit from such therapies. Expression of PD-L1, among other biomarkers, is associated with response; however, owing to tumor heterogeneity and the fact this biomarker is not static, biopsies are not suitable. Furthermore, biopsies are invasive and unsuitable for repeated testing.

Novel research from an international team led by Jinkai Teo (Merck Research Laboratories, Singapore) sought to solve this problem using peripheral blood samples, and a less-invasive approach.

Whole blood from both healthy donors and breast cancer patients underwent circulating tumor cell enrichment and was loaded onto a microfluidic chip, undergoing chipcytometry.

The results demonstrated that the workflow had a mean detection rate of 22.8%, and could determine PD-L1 and PD-L2 expression levels.

"We believe the main advantages of chipcytometry lie in the iterative staining process that allows retrospective evaluation of additional markers and the potential to measure a large number of parameters without the spillover/compensation problems encountered with flow cytometry," commented the authors. "This approach allows the analysis of additional immunomodulatory targets on tumor cells beyond PD-L1 and PD-L2, which is particularly critical, considering high dimensional analysis of these markers is likely to become increasingly relevant as immunotherapy moves beyond the administration of single immunomodulatory agents toward combinations that synergize in their antitumor immune response."

Furthermore, the potential to include more positive or negative markers could allow increased confidence that identified cells are CTCs.

However, the authors note that these data are preliminary, and further experimentation is needed to fully establish feasibility of the approach.

Provided by Future Science Group