Advances in precision medicine help refine – and redefine – cancer care

Among the groundbreaking findings presented at this year’s annual meeting of the American Society of Clinical Oncology were those showing that most women with HR-positive, HER2-negative, early-stage breast cancer who have an intermediate recurrence score can safely skip adjuvant chemotherapy, and that upfront pembrolizumab for patients with NSCLC expressing PD-L1 on at least 1% of tumor cells can not only significantly improve overall survival, but do so with less toxicity than standard chemotherapy.

TAILORx marks major advance for precision medicine in breast cancer

Key clinical point The majority of women with HR-positive, HER2-negative, node-negative early-stage breast cancer who have an intermediate recurrence score can safely skip adjuvant chemotherapy. Major finding In women with an Oncotype DX Recurrence Score in the midrange (11-25), invasive DFS with endocrine therapy alone was not inferior to that with chemotherapy plus endocrine therapy (HR, 1.08; P = .26). Study details A phase 3 trial in 10,273 women with HR-positive, HER2-negative, node-negative, early-stage breast cancer, with a noninferiority randomized component in the 6,711 women with a midrange recurrence score (TAILORx trial). Funding This study received funding primarily from the National Cancer Institute, National Institutes of Health. Additional support was provided by the Breast Cancer Research Foundation, Komen Foundation, and US Postal Service Breast Cancer Stamp. Disclosures Dr Sparano disclosed that he has a consulting or advisory role with Genentech/Roche, Novartis, AstraZeneca, Celgene, Lilly, Celldex, Pfizer, Prescient Therapeutics, Juno Therapeutics, and Merrimack; has stock or other ownership interests with MetaStat; and receives research funding (institutional) from Prescient Therapeutics, Deciphera, Genentech/Roche, Merck, Novartis, and Merrimack. Source Sparano et al. ASCO 2018 Abstract LBA1: https://meetinglibrary.asco.org/record/161490/abstract

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 meeting and simultaneously published in the New England Journal of Medicine (N Engl J Med. 2018; 379:111-121; [behind paywall]), 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, commented 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 although they could have benefited from it,” he noted.

The recurrence score is known to be prognostic and 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, which is about two-thirds of all patients who are treated,” said Dr Sparano, the 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.

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 is that 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 (DFS) 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 [HR], 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 (OS).

Findings were similar across most subgroups. But analyses suggested that women aged 50 years and younger and who had a recurrence score of 16-25 fared better when they received chemotherapy. “Though exploratory from a statistical perspective, this is a highly clinically relevant observation,” Dr Sparano said. “It suggests ... that chemotherapy should be spared with caution in this subgroup, after a careful discussion of potential benefits and risks in a shared decision process.”

In other findings, analyses of the trial’s nonrandomized groups confirmed excellent outcomes in women with a low recurrence score (0-10) who were given endocrine therapy alone, and at the other end of the spectrum, there was need for a more aggressive approach, including chemotherapy, in women with a high recurrence score (26-100).

Ultimately, application of the recurrence score allowed 69% of the trial population to skip chemotherapy: all of the women with a score of 0-10 (16% of the trial population), those older than 50 years with a score of 11-25 (45%), and those aged 50 years or younger with a score of 11-15 (8%).

An ongoing companion phase 3 trial, RxPONDER, is assessing the benefit of applying the recurrence score in women who are similar but ihave node-positive disease.