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Agendia Studying Effect of Forgoing Chemo in Early-Stage MammaPrint Low-Risk Breast Cancer Patients

NEW YORK – Agendia on Thursday said it began enrolling patients in the PROOFS registry trial to evaluate whether premenopausal women with early-stage hormone receptor (HR)-positive breast cancer can avoid chemotherapy if they are classified as being at low risk by its MammaPrint multi-gene expression test.

Women in the study will receive temporary ovarian function suppression (OFS) in combination with endocrine therapy instead of chemo if they are clinically high risk but classified by MammaPrint as being at low risk of breast cancer recurrence. Agendia is conducting the study in partnership with the West German Study Group (WSG) and aiming to enroll 1,500 patients via 100 sites in Germany by January 2025.

The results from the earlier Phase III MINDACT trial suggested that using Agendia's MammaPrint can reduce chemotherapy in women who are clinically high risk but low risk according to the test. However, between 3 percent and 5 percent of postmenopausal women with MammaPrint low-risk scores appeared to benefit from added chemotherapy in MINDACT. The researchers involved in the PROOFS trial believe the benefit seen in this subset of patients was due to chemotherapy-induced ovarian function suppression, and they now hope to show definitively that MammaPrint low-risk patients can temporarily suppress their ovaries and forgo chemotherapy without negative outcomes.

"While chemotherapy is often assumed to be necessary for all young women with hormone receptor-positive breast cancer, we have been able to harness the power of gene expression profiling to understand the biology of each breast cancer beyond the effects of age and standard pathology, and better define the true benefit of treatment," William Audeh, chief medical officer at Agendia, said in a statement. "These insights could allow some young women with breast cancer to forgo chemotherapy and avoid unnecessary toxicity."

Along with reducing toxicity, forgoing chemo would also allow young women with breast cancer to preserve their fertility, Oleg Gluz, scientific director of the WSG, said in a statement.

Agendia, which is based in Amsterdam and has its US offices in Irvine, California, is exploring the impact of adjuvant endocrine therapy de-escalation in another study involving postmenopausal breast cancer patients who are classified by MammaPrint as having "ultra-low" risk of recurrence. The firm is also developing ImPrint, an assay to help guide neoadjuvant immunotherapy treatment for early-stage breast cancer patients.