Agendia's MammaPrint 70-gene panel can be used to refine risk in patients 50 years of age and younger with early breast cancer, which may be helpful in guiding some to less-intensive treatment regimens, according to a poster study presented by the company at the San Antonio Breast Cancer Symposium (SABCS).
The company presented data at the meeting, which is being held December 10-14, from a subanalysis of the previously reported Prospective Study of MammaPrint in Patients With an Intermediate Recurrence Score (PROMIS). PROMIS evaluated MammaPrint in women with stage I/II node-negative, hormone receptor-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer who had an intermediate risk score (18-30) on the 21-gene Oncotype DX test (Exact Sciences). The goal was to add information that was helpful in determining whether patients needed chemotherapy on top of endocrine therapy in the adjuvant setting.
The subanalysis was performed to explore MammaPrint's utility in patients 50 years and younger, who the poster authors described as a "group left incompletely addressed" in the landmark Trial Assigning Individualized Options for Treatment (TAILORx) of the Oncotype DX test. Currently, chemotherapy and endocrine therapy are typically recommended for patients 50 years and younger with an Oncotype DX risk score between 16 and 25.
In its latest analysis, Agendia divided a PROMIS subset of 181 women who were 50 years old or younger into three Oncotype DX risk groups: 18 to 20, 21 to 25, and 26 to 30. The company reported that MammaPrint could help identify up to 46% of patients with a risk score in the 21-to-25 range who are at low risk for recurrence and may not need chemotherapy.
What lies beneath ethnicity
In separate posters presented at SABCS, the company presented analyses of its risk scoring products in ethnic subgroups with breast cancer: MammaPrint for risk recurrence and also BluePrint, which analyzes 80 genes and stratifies tumors into three categories (luminal-type, HER2-type, and basal-type).
One study analyzed test results and clinical-pathological features for a total of 66 ethnic Chinese patients living in the U.S. and Hong Kong. The researchers compared them with analyses taken from randomly selected, age-matched Caucasian and African American breast cancer patients enrolled in Agendia's prospective Full-Genome Data Linked With Clinical Data to Evaluate New Gene Expression Profiles (FLEX) registry study.
Chinese patients living in the U.S. were more likely to be younger, have grade 3 tumors, and have lymph node involvement than their counterparts in Hong Kong, Chief Medical Officer Dr. William Audeh and colleagues reported in the poster. They were also more likely to have HER2-type tumors, though this was not a statistically significant result.
"These findings suggest a possible interaction between genetics and lifestyle factors, and perhaps influenced by immigration," Audeh and colleagues concluded. "Further study is needed to validate these trends, and future studies of breast cancer in ethnic subpopulations should incorporate evaluation of genomic profiling."
A third poster presentation at SABCS explored the nature of breast cancers in 263 African American women enrolled in the FLEX study. Compared with Caucasians, African Americans tend to develop cancer earlier, have more aggressive types, and have worse outcomes. Breast cancer has a distinct transcriptional profile in African Americans versus Caucasians, Audeh and colleagues noted. Differentially expressed genes in basal-type cancer "suggest ethnicity and/or other clinical characteristics, such as metabolic factors," play a role in progression in African Americans, according to the authors.
"This study identifies candidate genes for further study in elucidating the molecular biology of breast cancer in [African Americans]," they concluded.