53 The development of a multi-institutional prospective registry for patients with metastatic invasive lobular carcinoma: identifying new markers of disease progression

OBJECTIVES/GOALS: We are launching a multi-center prospective registry for patients with metastatic invasive lobular carcinoma (ILC), the second most common type of breast cancer, to better understand patterns of progression, imaging features of metastatic sites, and if serial cell free DNA measurements can serve as a surrogate marker of disease progression. METHODS/STUDY POPULATION: Patients with biopsy proven metastatic ILC of any receptor subtype will be included in the registry. We will exclude patients with ductal histology only or those with multiple primary malignancies. Patients will be enrolled at four large academic medical centers across the country. Cell free DNA measurements using a tumor informed assay will be obtained every 3 months concurrent with regular clinical imaging. Disease status will be determined by the patient’s medical oncologist by taking into account imaging, tumor markers, symptoms, and cell free DNA measurement. At each time point, patients will be surveyed on their quality of life and their medical oncologists will be asked to rate the clinical utility of the cell free DNA value. Patients will be followed indefinitely. RESULTS/ANTICIPATED RESULTS: We will explore whether the use of serial cell free DNA or a combination of blood-based biomarkers and clinical endpoints can reliably identify treatment response and disease progression in patients with metastatic ILC. Many patients with metastatic ILC have unmeasurable disease on imaging and are thereby excluded from clinical trials. The end goal of this registry is to determine if blood-based biomarkers can be used as a proxy for measurable disease in ILC patients and therefore increase clinical trial enrollment for this subgroup of patients. DISCUSSION/SIGNIFICANCE: The creation of this prospective registry will open the door for future studies of blood-based markers that reflect disease stability and progression, which is an unmet need specifically in ILC. Identification of such markers could lead to a novel treatment response endpoint, changing the way patients are enrolled in trials and managed clinically.