Genomic Profiling Can Improve PFS in Metastatic Breast Cancer

Pam Harrison

December 07, 2021

Genomic profiling improves outcomes for patients with metastatic breast cancer as long as the alteration-drug match has good clinical trial evidence supporting its use, a new pooled analysis suggests.

"The message is very simple," lead study author Fabrice Andre, MD, PhD, research director, Gustave Roussy Cancer Campus, Villejuif, France, told Medscape Medical News during a virtual press briefing. "If a genomic alteration is validated, it is useful to give targeted therapy, but if the genomic alteration is not validated, we should not give a targeted therapy."

The study, which pooled results from phase 2 randomized trials SAFIR02-BREAST and SAFIR-P13K, was presented today in a virtual press briefing at the San Antonio Breast Cancer Symposium (SABCS) 2021.

The new analysis explored two key questions: Is genomic testing of a cancer effective? And how should oncologists interpret a genomic report?

A total of 1462 patients with metastatic HER2-negative breast cancer underwent next-generation sequencing. After receiving six to eight cycles of chemotherapy, 238 patients (16%) were randomized to one of nine targeted therapies matched to the genomic alteration identified on testing or to maintenance chemotherapy.

Genomic alterations in the patients' tumors were classified using the ESMO Scale of Actionability of Molecular Targets (ESCAT). A tier I ranking indicates that the alteration-drug match is associated with improved outcomes in clinical trials, while a tier II ranking means that the alteration-drug match is associated with antitumor activity but the magnitude of benefit remains unknown.

In an analysis of the overall trial population, Andre and colleagues found an improvement in progression-free survival in the targeted therapy group (median of 5.5 months) in comparison with the maintenance chemotherapy group (2.9 months), but the difference was not significant (P = .109).

In a subgroup of 115 patients presenting with I- or II-tier genomic alterations, median progression-free survival was 59% longer, at 9.1 months, among patients receiving targeted therapy, compared with 2.8 months in the maintenance chemotherapy group (hazard ratio, 0.41; P < .001).

In addition, the team carried out single-nucleotide polymorphism (SNP) array analyses on 926 patients. They identified 21 genes that were altered more frequently in the metastases compared with the primary tumors, and they observed that a high homologous recombination deficiency score in patients with BCRA 1 or 2 mutations was associated with a longer progression-free survival in patients treated with olaparib.

"We also identified a subset of patients who are resistant to CDK4/6 inhibitors who presented with CDK4 amplification, and this amplification is associated with overexpression," Andre explained.

When asked whether most oncologists were using genomic profiling to tailor treatment for breast cancer patients, Andre said that multigene sequencing is now widely used.

"The issue is not so much whether we should use or not use genomics; the issue here is to force everyone to put the genomic alteration in the right context in terms of its level of evidence," Andre told Medscape Medical News.

Oncologists may overinterpret the genomic activation identified and give a targeted therapy that is not validated, but "oncologists should not use genomic information when the target has not been previously validated in a therapeutic trial," he added.

Virginia Kaklamani, MD, professor of medicine at the University of Texas Health Sciences Center in San Antonio, told Medscape Medical News that approximately 5 years ago, Andre was part of the first debate at the SABCS discussing whether oncologists should be conducting next-generation sequencing for their patients with breast cancer.

"At the time, Andre's comment was that we should not be doing it," recalled Kaklamani, who is also leader of the breast cancer program at the Mays Cancer Center at the University of Texas Health San Antonio MD Anderson. "At that point, I think it was clear that we did not have the data we needed to be able to use next-generation sequencing to change our clinical management."

However, the evidence has evolved. "Based on this clinical trial, I think we now do have the data," she said. "I think that [next-generation sequencing] is something we will be using more and more in practice and treating our patients based on [validated] genomic alterations."

Andre has received grants or advisory board/speaker honoraria from Daiichi Sankyo, Roche, Pfizer, AstraZeneca, Lily, and Novartis. Kaklamani has served as a consultant for Puma, AstraZeneca, Athenex, and Immunomedics, has received research funding from Eisai, and has served as a speaker for Pfizer, Celgene, Genentech, and Genomic Health, among other companies.

San Antonio Breast Cancer Symposium (SABCS) 2021: Presented December 7, 2021.

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