35 TIP A Pragmatic Clinical Trial to Determine the Best Treatment Decision in Relapsed Metastatic Breast Cancer With Discordant Tumor Receptors

Background

Annually, around 680,000 people die of metastatic breast cancer (MBC) worldwide. The median life expectancy for those with MBC is 2 to 3 years. In 15% to 25% of relapsed MBC (rMBC) cases, the tumor receptors (ER, PR, HER2) of a biopsied metastatic tumor are discordant from the receptors of the original primary tumor. Current standards recommend the biopsy and retesting of metastatic tumors to determine receptor status. Those same standards indicate no data exists to support basing first-line treatment decisions on the receptor status of metastatic tumors. Observational data are sparse and inconclusive on the impact of such decisions on median survival. Evidence suggests that changes to first-line treatment plans based on retested tumor receptor status harm patient outcomes. This trial builds on the existing literature and the author’s research previously presented at this conference to study the impact of basing patients’ first-line treatment plans with discordant tumors on the primary versus the metastatic receptors. Evidence indicates this decision could impact 12 to 40 months of life expectancy. The goal of this trial is to identify the best treatment strategies for rMBC patients with discordant tumors to extend life expectancy.

Materials and Methods

This trial involves a treatment decision. The proposed trial is a pragmatic, prospective, multicenter intervention with limited exclusion criteria. The population of interest is patients with rMBC who have discordant receptors. Once informed and consented, patients will be randomized to have their first-line treatment plan based on either their primary or metastatic tumor receptors. Within that context, the treatment is physician/patient choice. Evaluators and statisticians will be blinded. Patients will receive their first evaluation/scan 3 months after randomization. From that point forward, care decisions are physician/patient choice. Patients will be tracked for key variables until the trial’s conclusion. The primary study end point is overall survival (OS). Kaplan-Meier and Cox regression will be the key analytical tools utilized. This trial will have IRB approval.

Status

The trial has been designed and submitted for grant funding. The trial is expected to initiate enrollment in late 2023 with an enrollment over a 3-year period of 300 patients evenly allocated to both arms. The trial is expected to last 5 years from initiation.

AFFILIATION:

Amy Foster Research Fellow, Department of Business Analytics and Statistics, University of Tennessee, Knoxville, TN.