Abstract PO5-03-07: Impact of age and stage on pathologic complete response rates in Black vs White patients with triple negative breast cancer

Abstract Background Triple-negative breast cancer (TNBC) accounts for approximately 10-15% of breast cancers. Women with TNBC have worse survival outcomes, increased rates of relapse, and distant metastasis as compared to women with non-TNBC. Regardless of subtype, Black women have worse breast cancer outcomes than White women. Early stage treatment of TNBC has focused on neoadjuvant therapy (NACT) with a goal of achieving a pathologic complete response (pCR), which is associated with longer event-free survival and overall survival in TNBC patients. NACT with pembrolizumab was presented at the San Antonio Breast Cancer Symposium in December 2019 and FDA approved in July 2021. The Keynote-522 Trial found that patients who received NACT + pembrolizumab were more likely to achieve pCR than women who received NACT + placebo, regardless of stage. The KEYNOTE-522 trial did not examine race or age differences in treatment efficacy. Since TNBC disproportionately affects younger women and Black women, optimizing pCR rates in these groups is essential. Our objective is to examine racial differences in pCR rates by cancer stage and age among patients with TNBC who completed NACT/pembrolizumab. Methods Patient records from Ochsner Health, a regional network, were reviewed for those with early stage TNBC who had completed treatment with NACT/pembrolizumab from January 2020 to January 2022. Exclusion criteria included no surgical treatment for TNBC, unknown receptor status, and age 18 years-old. Chi-square and Fisher’s Exact tests were used to examine the relationship between race and pCR stratified by stage at diagnosis and age. Risk ratios and 95% confidence intervals were also estimated to examine the strength of these relationships. Results We identified 92 patients with TNBC who completed treatment with NACT/pembrolizumab and underwent surgery. 52 patients (56%) were Black and 40 patients (43%) were White. 53.85% of Black patients had pCR and 67.50% of White patients experienced pCR (p=0.19). Among patients with stage III disease, only 37.50% of Black patients experienced pCR compared to 69.23% of White patients (p=0.09). Notably, Black patients were 46% less likely to experience pCR than = White patients (RR: 0.54, 95% CI: 0.28-1.02) in the stage III group. Among patients less than 50 years of age, 41.18% of Black patients experienced pCR compared to 84.21% of White patients (p=0.01), where younger Black patients were 51% less likely to experience pCR than younger White patients (RR: 0.49, 95% CI: 0.27-0.89) There were no observed racial differences in pCR rates for stage I/II patients (p=1.00) or patients aged 50 years or older (p=0.64). Discussion These data demonstrate that Black women are at a pCR rate disadvantage receiving NACT/pembrolizumab. This is primarily driven by advanced stage and young age. Black patients with stage III cancers had significantly lower pCR rates than their White counterparts after having received the same treatment. Additionally, young patients who are Black have significantly lower pCR rates. For older patients and those with stage I/II disease, there was no statistically significant difference in pCR rates between Black vs White race. Conclusion While NACT/pembrolizumab offers overall increased rates of pCR, Black women, especially those who are young or with more advanced disease at presentation, still have worse outcomes. Further research is needed to determine underlying predictors or alternative treatments to benefit these populations. Table 1 Distribution of Pathological Complete Response Following NACT/pembrolizumab treatment (Nf91) Table 2 Crude Risk Ratios for the Relationship between Race and Pathological Complete Response by Age and Stage (Nf92) Citation Format: Melanie Sheen, Caitlin Taylor, Rabia Cattie, Melyssa Bratton, Meredith Lakey, Victoria Chung, Erin Biggs. Impact of age and stage on pathologic complete response rates in Black vs White patients with 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 PO5-03-07.