Diagnostic Advances in Metastatic Breast Cancer
I continue
to be encouraged by advances in the use of circulating tumor cell (CTC)
analysis in cancer treatment, but so much work needs to be done. In a recent
study led by Martine Mazel from University Medical Centre in Montpellier,
France, researchers have demonstrated the ability to gauge PD-L1 expression
from liquid biopsies of metastatic breast cancer patients. Immune checkpoint regulators are becoming
increasing important and have given rise to the development of immunotherapies
for cancer treatment. PD-L1 is an immune checkpoint regulator targeted by a
number of approved and developmental oncology therapies.
Using the
CELLSEARCH® System developed by Janssen Diagnostics, researchers tested blood
samples from 16 women with hormone receptor-positive, HER2-negative metastatic
breast cancer and found 11 patients had a subpopulation of CTCs with weak or
strong PD-L1 expression. These results indicate that CTC analysis for PD-L1
expression is feasible and when confirmed, could open up the opportunity to
predict response to certain therapies in future, larger studies using a blood
test rather than tissue biopsy. In a research setting, the CELLSEARCH® System
offers the ability to capture CTCs via a routine blood test.
"I
believe we have demonstrated that CTC characterization for PD-L1 expression is
feasible using a CTC platform. This paves the way for the utilization of a
CTC/PD-L1 assay in future clinical trials to explore whether it can stratify
patients according to response, and potentially predict the efficacy of immune
checkpoint blockade," commented study investigator Catherine
Alix-Panabieres, Ph.D., Director of the Laboratory of Rare Human Circulating
Cells, University Medical Centre of Montpellier, University of Montpellier
EA2415, Montpellier, France.
CTCs have
the potential to allow real-time, dynamic monitoring of tumor characteristics
without the need for repeated invasive biopsies. It was demonstrated earlier
that CTC expression of key biomarkers such as HER21, IGFR2, c-MET3 and other
proteins can be monitored successfully. This publication in Molecular Oncology
underscores the potential of CELLSEARCH® CTC testing to also become an
important tool in cancer immunotherapy.
Yet
according to a recent article in MIT
Technology Review, “new diagnostics can find the DNA that drives a tumor,
but evidence that they help patients is missing”. “You have tests coming to
market that are sometimes proven and sometimes unproven,” says Tycho Peterson,
an analyst at J.P. Morgan who tracks the industry. “Commercial activity is
increasing very quickly.” He estimates $20 billion a year in tests globally by
2020, up from about $100 million today. But we are a long way from the liquid biopsy
being used to detect cancer before symptoms arise. All the more reason that the
National Foundation for Cancer
Research continues to support the work of Dr. Daniel Haber, Director of the
Massachusetts General Hospital in Boston, and his collaborators. We have continuously supported this important
research since 2004, and I believe this ultimately will help patients across
ALL CANCERS.