US-based life sciences company NanoString Technologies' breast cancer assay, based on the PAM50 gene expression signature, has met its primary and secondary endpoints in a second clinical validation study.
The CE-marked breast cancer assay provides a subtype classification, based on the fundamental biology of an individual's breast tumor (intrinsic subtyping), as well as a prognostic score (ROR score), which indicates the risk of distant recurrence in postmenopausal women with hormone receptor-positive (HR+) early-stage breast cancer, treated with endocrine therapy alone.
The study, performed by British Columbia Cancer Agency (BCCA), evaluated 1,478 stored formalin-fixed paraffin-embedded (FFPE) patients samples using the nCounter Analysis system, installed at BCCA's Center for Translational and Applied Genomics.
The patients who were evaluated are a part of the Austrian Breast & Colorectal Cancer Study Group 8 (ABCSG8) trial, according to the company.
University of British Columbia pathology professor and study lead pathology investigator Dr Torsten Nielson said the automated nCounter Analysis system is used in hospital pathology laboratory to accurately measure RNA extracted from standard FFPE tissue samples with minimal hands-on time.
"On these clinical specimens, 97% of the breast cancer samples that passed the pre-specified tissue and RNA metrics yielded intrinsic subtype and ROR results," Nielson said.
The risk categories defined by pre-specified ROR score cut-points (low risk, intermediate risk, and high risk) also separated the patients into risk groups with statistically significant different outcomes at 10 years.
In addition, the results showed that Luminal A subtypes have better outcomes than Luminal B subtypes independent of nodal status in postmenopausal women with HR+ early-stage breast cancer treated with endocrine therapy alone.
Medical University of Vienna professor, ABCSG president and study lead clinical investigator Dr Michael Gnant said; "These results confirm the key findings of the TransATAC study presented last year, and together these two studies provide strong evidence for the PAM50 test's clinical validity."
The PAM50 gene signature is not cleared for sale in the US, while the nCounter Analysis system is labeled for research use only.