Abstract PO3-20-05: Phase II Study of Genomically Guided Radiation Dose Personalization in the Management of Triple Negative Breast Cancer

Abstract Background: Our group has previously developed the radiosensitivity index (RSI) using a multigene expression model that is directly proportional to tumor radioresistance (high RSI = increased radioresistance). RSI has been previously validated in two datasets of patients with triple negative breast cancer (TNBC). In this study, we will run a selective dose personalization study in TNBC patients undergoing breast conservation therapy (BCT). Based on patients RSI scores, they will either receive a radiation therapy (RT) boost of 10 Gy to the tumor cavity or not. Given our data in two independent datasets, the current study will reveal the feasibility and benefit of selective genomic dose personalization in TNBC following BCT. Trial Design: The study is designed as a prospective, nonrandomized, phase II trial of genomically guided RT in the management of TNBC undergoing BCT. Patients will be allocated to one of two groups based on their RSI determination from fresh frozen tissue collected by biopsy or at the time of BCT. These groups will be Group A, RSI optimized whole breast radiotherapy alone or with a 10 Gy boost or Group B, RSI not optimized whole breast radiotherapy with a boost of 10 Gy to tumor cavity. Patients will receive standard of care chemotherapy, neoadjuvant or adjuvant. Eligibility: TNBC patients undergoing BCT. Specific Aims: To determine the three-year local control following genomically guided dose personalization in the management of TNBC following BCT. Secondary objectives include determination of overall survival (OS), progression free survival (PFS), and quality of life (QOL) following genomically guided dose personalization. Statistical Methods: The primary hypothesis is the three-year local control rates differ for groups A and B, against the null hypothesis that the two rates are identical. Patients will allocate approximately 78% in group A and 22% in group B and local control rates are expected to be 96% and 75%, respectively. Assuming 80% power and 10% type I error for a log-rank test, 86 patients are needed. An interim analysis will be completed when 4 disease progression events are observed. There will be approximately 43 patients at the time of interim analysis. Patient Accrual: This study is open with 1 patient enrolled at the time of submission. A total of 86 patients will be enrolled. Contact Information: Kamran A. Ahmed MD, Moffitt Cancer Center, email: kamran.ahmed@moffitt.org, Clinical trial information: NCT05115474. Funding: Moffitt and Morton Plant Mease Foundations. Citation Format: Kamran Ahmed, Iman Washington, Matthew Mills, Michelle DeJesus, Youngchul Kim, Ronica Nanda, Javier Torres-Roca, Steven Eschrich, Janis De La Iglesia, John Puskas, Marilin Rosa, Jason Wilson, Paula Lundgren, Negar Golesorkhi, Nazanin Khakpour, Susan Hoover, Marie Lee, John Kiluk, Melissa Mallory, Christine Laronga, Laura Kruper, Brian Czerniecki, Roberto Diaz. Phase II Study of Genomically Guided Radiation Dose Personalization in the Management of Triple Negative Breast Cancer abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-20-05.