Clinical implications of prospective genomic profiling of metastatic breast cancer pa
Clinical implications of prospective genomic profiling of metastatic breast cancer patients
Abstract
Background: Metastatic breast cancer remains incurable. Next-generation sequencing (NGS) offers the ability to
identify actionable genomic alterations in tumours which may then be matched with targeted therapies, but the
implementation and utility of this approach is not well defined for patients with metastatic breast cancer.
Methods: We recruited patients with advanced breast cancer of any subtype for prospective targeted NGS of their
most recent tumour samples, using a panel of 108 breast cancer-specific genes. Genes were classified as actionable
or non-actionable using the European Society of Medical Oncology Scale for Clinical Actionability of Molecular
Targets (ESCAT) guidelines.
Results: Between February 2014 and May 2019, 322 patients were enrolled onto the study, with 72% (n = 234) of
patients successfully sequenced (n = 357 samples). The majority (74%, n = 171) of sequenced patients were found to
carry a potentially actionable alteration, the most common being a PIK3CA mutation. Forty-three percent (n = 74) of
patients with actionable alterations were referred for a clinical trial or referred for confirmatory germline testing or
had a change in therapy outside of clinical trials. We found alterations in AKT1, BRCA2, CHEK2, ESR1, FGFR1, KMT2C,
NCOR1, PIK3CA and TSC2 to be significantly enriched in our metastatic population compared with primary breast
cancers. Concordance between primary and metastatic samples for key driver genes (TP53, ERBB2 amplification) was
> 75%. Additionally, we found that patients with a higher number of mutations had a significantly worse overall
survival.
Conclusion: Genomic profiling of patients with metastatic breast cancer can have clinical implications and should
be considered in all suitable patients.
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