Genomic test may help indicate which patients with breast cancer can avoid chemotherapy and have similar outcomes

New results from a large randomized clinical trial suggest a genomic test may identify many people with breast cancer who can avoid chemotherapy, while having similar long-term outcomes to patients who undergo chemotherapy.The results provide evidence that the genomic test, called Prosigna, can help decide if chemotherapy is necessary for a broad group of patients, including those who are premenopausal or have many lymph nodes affected. The results come from the OPTIMA trial, a phase III randomized clinical trial involving more than 4,400 patients over 40 years old with early breast cancer who were randomized to receive standard protocol or treatment directed by the Prosigna test. All patients had ER+ HER2- breast cancer involving either none or up to nine axillary nodes. After the patients had surgery to remove the tumour, they were randomized to either chemotherapy followed by endocrine therapy versus a Prosigna test-directed treatment. In the test-directed treatment group, those with a Prosigna risk of recurrence (ROR) score higher than 60 were assigned to chemotherapy followed by endocrine therapy and those with a Prosigna ROR score of 60 or lower received endocrine therapy alone. The study was presented at the American Association of Clinical Oncology annual meeting held in Chicago in late May. The five-year survival of the test-directed treatment group was not inferior to the standard treatment protocol group. The five-year invasive breast cancer-free survival rate was 91.5% in the standard protocol group and 90.4% in the test-directed group. For the people who had low Prosigna ROR scores, there was a five-year invasive breast cancer-free survival rate of 94.5% in the standard protocol group and 93.7% in the test-directed group, leaving a hazard ratio of 1.06 which showed non-inferiority. A statistical analysis suggested that only 2% of patients with a low Prosigna ROR score treated with chemotherapy would benefit from the treatment.Outcomes were similar for pre- and post-menopausal women. There was no difference in outcomes based on the number of affected lymph nodes.“OPTIMA provides robust, practice‑changing evidence that we can safely reduce the use of chemotherapy for many patients with hormone‑sensitive breast cancer,” said Dr. Iain MacPherson, co-chief investigator and professor of breast oncology at the University of Glasgow in a university press release. “These findings represent a major step forward in delivering more personalized, precise care, ensuring that treatment decisions are driven by what will genuinely improve outcomes for patients, while avoiding unnecessary toxicity. The potential impact for both patients and health services is substantial.”The test was co-developed more than 20 years ago by Dr. Torsten Nielsen, a professor of pathology and laboratory medicine at the University of British Columbia, along with Dr. Charles Perou, from the University of North Carolina-Chapel Hill, Dr. Matthew Ellis, then at the University of Washington and Dr. Philip Bernard of the University of Utah. It analyzes 50 genes within a breast cancer tumour in order to determine the tumour’s molecular subtype, which can help estimate the risk of cancer recurrence. Called PAM50, it's marketed under the name Prosigna and approved for use in Canada, the United States and Europe. “For many people diagnosed with breast cancer, one of the most difficult questions is whether chemotherapy is truly necessary. These results provide strong evidence that we can take a precision medicine approach and identify many patients who can safely avoid chemotherapy while maintaining excellent outcomes,” said Dr. Nielsen in a UBC press release. Dr. Nielsen is also the director of the MD/PhD program at the UBC faculty of medicine.Researchers have previously tested other multi-gene assays to decide if patients can safely forgo chemotherapy. One was the MammaPrint 70-gene signature assay, tested in the MINDACT trial. A 21-gene assay was examined in the RxSPONDER trial was another one. These trials had slightly different patient populations. The OPTIMA trial reflected a broader mix of patients, including pre-menopausal women and those with more extensive diseases.Researchers at the University College London and the University of Glasgow led the OPTIMA trial. It involved patients from the U.K., Norway, Sweden, Australia, New Zealand and Thailand.The study’s abstract was published in the Journal of Clinical Oncology.

Genomic test may help indicate which patients with breast cancer can avoid chemotherapy and have similar outcomes

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