TAILORx marks major advance for precision medicine in breast cancer

June 6, 2018|Family Practice News

REPORTING FROM ASCO 2018

CHICAGO – Use of the 21–tumor gene expression assay (Oncotype DX Recurrence Score) allows nearly 70% of women with hormone receptor–positive, HER2-negative, node-negative early-stage breast cancer to safely forgo adjuvant chemotherapy, sparing them adverse effects and preventing overtreatment, TAILORx trial results show.

The findings, which were reported in the plenary session at the annual meeting of the American Society of Clinical Oncology and simultaneously published in the New England Journal of Medicine, mark a major advance in precision medicine.

“The rationale for the TAILORx precision medicine trial is that we are really trying to ‘thread the needle,’ ” lead study author Joseph A. Sparano, MD, associate director for clinical research at Albert Einstein Cancer Center and Montefiore Health System in New York, and vice chair of the ECOG-ACRIN Cancer Research Group, explained in a press briefing. Oncologists typically recommend adjuvant chemotherapy for the half of all breast cancers that are hormone receptor positive, HER2 negative, and node negative, even though its absolute benefit in reducing recurrences in this population is small. “This results in most patients being overtreated because endocrine therapy alone is adequate. But some are undertreated: They do not receive chemotherapy but could have benefited from it,” he noted.

The recurrence score is known to be prognostic and to be predictive of benefit from adding chemotherapy to endocrine therapy, Dr. Sparano said. “But there was a major gap: There was uncertain benefit for patients who had a midrange score, about two-thirds of all patients who are treated.”

The phase 3 TAILORx trial registered 10,273 women with hormone receptor–positive, HER2-negative, node-negative early-stage breast cancer, making it the largest adjuvant breast cancer trial to date. Analyses focused on the 6,711 evaluable women with a midrange recurrence score (defined as 11 through 25 in the trial), who were randomized to receive endocrine therapy alone or adjuvant chemotherapy plus endocrine therapy, with a noninferiority design. Of note, contemporary drugs and regimens were used.

Results at a median follow-up of 7.5 years showed that the trial met its primary endpoint: The risk of invasive disease-free survival events (invasive disease recurrence, second primary cancer, or death) was not inferior for women given endocrine therapy alone compared with counterparts given chemotherapy plus endocrine therapy (hazard ratio, 1.08; P = .26), Dr. Sparano reported.

The groups were also on par, with absolute differences of no more than 1% between rates, with respect to a variety of other efficacy outcomes: freedom from distant recurrence and any recurrence, and overall survival.