Aleix Prat, MD, PhD, head of the Department of Medical Oncology, the August Pi i Sunyer Biomedical Research Institute, discusses the results of the open-label PAMELA trial, in which the 

-enriched subtype predicted pathologic complete response (pCR) to targeted treatment in patients with HER2-positive, hormone receptor (HR)-positive breast cancer.

HER2-positive breast cancer is defined by immunohistochemistry and fluorescence in situ hybridization, but the disease is heterogenous, Prat explains. Prior studies defined 4 intrinsic subtypes of the disease. One of them, 

-enriched, suggests that it has the highest activation of the HER2 pathway. The prospective PAMELA trial treated 151 HER2-posiitve patients with trastuzumab (Herceptin), lapatinib (Tykerb), and endocrine therapy if the patient was also HR-positive. After 18 weeks, patients underwent surgery.

Results showed that the overall pCR rate was 30%. Among the HER2-enriched subtype, the pCR rate increased to 40.6%. In the non-enriched HER2 subgroup, the pCR rate was 10%. This shows that for patients with the HER2-enriched subtype, there is a high likelihood they will elicit a pCR with HER2-targeted agents, Prat says. This could lead to further reseach that will evaluate the activity of these patients on de-escalating treatment regimens, such as chemotherapy.

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Aleix Prat, MD, PhD, head of the Department of Medical Oncology, the August Pi i Sunyer Biomedical Research Institute, discusses the results of the open-label PAMELA trial, in which the HER2-enriched subtype predicted pathologic complete response to targeted treatment in patients with HER2-positive, hormone receptor-positive breast cancer.

Dr. Prat on HER2-Enriched Subtype as Strong Predictor of HER2-Targeted Treatment

Aleix Prat, MD, PhD, medical oncologist, Vall d’Hebron Institute of Oncology, Barcelona, Spain, discusses the differences between EndoPredict and Prosigna.

Prat says the two tests both work from paraffin tissue, but use different technologies and have their own gene list. EndoPredict, a multi-gene test for breast cancer patients, uses RTPCR platform and 8 genes while Prosigna, the only breast cancer genomic assay powered by the innovation of PAM50, uses the nCounter NanoString platform and 50 genes.

There are only two genes that overlap between the two tests, Prat says. Both tests were also derived in different cohorts -- EndoProdict was developed from a cohort of patients with luminal disease treated with endocrine therapy while the Prosigna assay was developed in a cohort of patients with all subtypes and no adjuvant therapy.

Prat says Prosigna provides intrinsic subtype information and the risk of recurrence for each patient while EndoPredict only provides prognostic data.

Aleix Prat, MD, PhD, medical oncologist, Vall D'Hebron Institute of Oncology, Barcelona, Spain, discusses the differences between EndoPredict and Prosigna.

Aleix Prat, MD, PhD

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Dr. Prat on HER2-Enriched Subtype as Strong Predictor of HER2-Targeted Treatment

Dr. Prat on the Differences Between EndoPredict and Prosigna