Researchers from Johns Hopkins University School of Medicine in Baltimore, Maryland, have used PET scans to identify biomarkers that may help predict which breast cancer patients can avoid chemotherapy treatment. The team published its findings online in the February issue of the Journal of Clinical Oncology.
Roughly 8 percent of all breast cancers are estrogen receptor (ER)-negative, HER2-positive. Standard treatment includes surgery to remove the tumor, antibody therapy to cut oﬀ the ability of the HER2 gene to support the growth of breast cancer cells and chemotherapy to kill the cancer cells.
In an effort to minimize toxicity and further individualize therapy, researchers found that the biomarker could determine which of these patients may benefit from standalone HER2-targeted agents without the need for chemotherapy.
“Although further studies are needed before the PET scan biomarker can be reliably used on a wide scale, the results of this study have the potential to advance the options for precision medicine in women with breast cancer,” senior author Vered Stearns, MD, co-director of the breast and ovarian cancer program at Johns Hopkins, said in a prepared statement.
For the study, Stearns and colleagues evaluated 83 of 88 women with stage II or stage III ER-negative, HER2-positive breast cancer. The women were recruited from nine Translational Breast Cancer Research Consortium medical facilities across the U.S.
PET scans using radioactive tracers to detect sugar uptake in cancer cells were then conducted before and 15 days after patients were given the first of four cycles of pertuzumab and trastuzumab (without chemotherapy) over a 12-week period.
The 88 women enrolled in the study were treated between January 2014 and August 2017; 83 were evaluated for the primary study, respectively. All four cycles of targeted therapy drugs were completed in 85 percent of cases and all 83 patients who completed follow-up had surgery after the therapy, according to the researchers.
The researchers then evaluated whether the PET images taken during the first stages of targeted therapy could help determine when the tumor would disappear completely after HER2-targeted treatment. After two weeks of treatment, the researchers could predict whether a patient would respond to HER2-targeted treatment without chemotherapy.
In more than half of the cases, the team observed a biomarker that could help them predict the outcome. Change in sugar uptake on PET scans from baseline to two weeks after starting treatment was one common biomarker. Another was the sugar level at the two-week time point.
High sugar levels two weeks after treatment indicated the tumor would likely not fully respond to antibodies alone and chemotherapy would be needed, the researchers noted.