Abstract PO-189: Racial disparities in attainment of pathological complete responses in HER2 positive breast cancer
Authors: Angell Callie , Bullock Jolonda , Diaz Anna , Basha Riyaz , Narra Kalyani 
Published: January 2022

Abstract
Pathologic complete response (pCR) is associated with the survival of breast cancer patients receiving neoadjuvant chemotherapy. John Peter Smith Hospital (JPS) has a high proportion of black patients, who have been shown to have lower pCR rates compared to non-Hispanic white (NHW) patients. The objective of this institutional study was to evaluate the racial and ethnic disparities in pCR rates of patients who received trastuzumab based neoadjuvant chemotherapy. A retrospective study was conducted using data from the institutional registry of the JPS Oncology and Infusion Center in Fort Worth, TX. Eligible patients were diagnosed with human epidermal growth factor receptor 2 (Her2) positive breast cancer between 1/1/2016 and 12/31/2019 and underwent neoadjuvant trastuzumab-based chemotherapy. Information on treatment regimen, diagnostic stage, hormone receptor (HR) status and demographic information were collected. The JPS Department of Pathology provided the pCR (ypT0/isypN0) data. JPS had 45 (NHW: 12, black: 15, and Hispanic: 11) eligible patients for this study. Of the 45 patients who underwent trastuzumab based neoadjuvant chemotherapy, 25 achieved pCR; 8 NHW, 7 Black, and 6 Hispanic. For HR negative patients, 3 of 4 NHW, 1 of 5 black, and 3 of 5 Hispanic patients achieved pCR for a total of 9 out of 17 patients. 40 of the 45 patients were treated with a regimen of docetaxol (T), carboplatin (C), trastuzumab (H), and pertuzumab (P), of which 21 achieved pCR. This study was limited by the number of eligible patients and should not be extrapolated to larger populations, but it shows the reality of an urban safety net hospital. It is interesting that overall, 67% of NHW patients achieved pCR, compared to 47% of black patients and with Hispanic patients in the middle at 55%. For HR negative cases, black patients were even less likely to have pCR. A previous study done by the University of Chicago found that the racial disparity in pCR rates was greatest in HR negative Her2 positive patients (Zhao et al, SABCS SS1-06). The neoadjuvant trials that tested pertuzumab in combination with trastuzumab and led to pertuzumab approval for Her2 positive breast cancer patients had few black patients, with 1.4% of patients being black in NEOSPHERE and 4% in TRYPHAENA, and neither commented on Hispanic patients. The data from TRYPHAENA showed 84% pCR for HR negative patients on P+TCH regimens, compared to 53% at JPS on similar treatment plans, and only 20% for HR negative black patients at JPS. Our institutional study supports the disparity in the effectiveness of the current treatment for Her2 positive breast cancer, especially for HR negative black patients, however, it is necessary to do more research to understand the response rates in black patients and planning for interventions for improving the outcomes. It is also important to further investigate the differences between ethnicities in treating Her2 positive breast cancer.
Citation Format: Callie Angell, Jolonda Bullock, Anna Diaz, Riyaz Basha, Kalyani Narra. Racial disparities in attainment of pathological complete responses in HER2 positive breast cancer [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-189.