Results from the OPTIMA trial were presented at the American Society of Clinical Oncology meeting, suggesting that genomic testing could help identify additional patients with hormone receptor-positive/HER2-negative early breast cancer who may be able to avoid adjuvant chemotherapy.

The trial found no benefit from chemotherapy in its complete per-protocol population. The difference in outcomes observed was 1.5%, which fell within the non-inferiority margin of 3% set for the trial. The OPTIMA trial also showed similar data for premenopausal women and for patients with up to nine positive lymph nodes.

Shimoli Barot, a doctor at Cleveland Clinic, discussed the trial's implications. "I think one of the most interesting updates at ASCO for early-stage breast cancer was the OPTIMA trial," Barot said. "I think that is going to be the most impactful, in terms of practice change, based on the results that we saw."

The OPTIMA trial focused on patients aged 40 and older who had completed local therapy, and it allowed for up to nine lymph nodes to be positive. Premenopausal women in the study received consistent ovarian function suppression. Participants were randomized 1:1 into either a control arm or a test-directed arm. The control arm received standard chemotherapy followed by endocrine therapy. In the test-directed arm, patients identified as higher risk received chemotherapy followed by endocrine therapy, while those identified as low risk received endocrine therapy alone. The Prosigna test was the genomic assay used in the trial.

Why It Matters

Genomic testing using tumor gene expression assays, such as the MammaPrint and Oncotype tests, is currently used to determine which patients with early-stage, hormone receptor-positive, HER2-negative breast cancer will benefit from chemotherapy in their adjuvant treatment after local therapy. While strong evidence supports the use of these tests for postmenopausal patients with up to three involved lymph nodes, data for premenopausal patients has been mixed due to inconsistencies in ovarian function suppression in previous trials. There has also been no data supporting the use of these tests for patients with more than three involved lymph nodes. The OPTIMA trial's design, including consistent ovarian function suppression and allowing for up to nine positive lymph nodes, addresses these prior limitations, suggesting a potential expansion of genomic testing's utility.

The trial was a time-driven analysis, with 63% of patients having less than a five-year follow-up. Women under 40 were excluded from the trial, and the patient population was primarily white.