Abstract P1-08-35: Stromal tumor infiltrating lymphocytes analysis by race and ethnicity in triple negative breast cancers from 2 phase III randomized adjuvant breast cancer trials: ECOG-ACRIN E2197 and E1199

Abstract

Abstract Background: Black patients with triple negative breast cancer (TNBC) have worse survival outcomes, even after adjusting for stage at diagnosis, income, insurance status and other socioeconomic factors. Little is known regarding anti-tumor immune responses in Black patients and how these differences affect responses to treatment in TNBC. Limited data exists regarding the stromal tumor infiltrating lymphocytes (sTILs, which are strongly prognostic in TNBC) distribution based on race and ethnicity. Here we evaluate the prevalence, distribution, and prognostic impact of sTILs in TNBC by race/ethnicity from 2 prospective clinical trials of adjuvant anthracycline/taxane-based chemotherapy (E2197 and E1199). Methods: Full-face hematoxylin and eosin-stained sections of 481 tumors from ECOG-ACRIN trials E2197 and E1199 were previously evaluated for density of sTILs and shown to be associated with disease-free survival (DFS), distant recurrence-free interval (DRFI), and overall survival (OS) (Adams, et al JCO 2014). Further analyses were undertaken to evaluate the impact of race/ethnicity. Results: The majority of the 481 TNBC were from White patients (82.3%, n=403); with 12.3% (n=59) Black patients, 1.6% (n=14) other (9 Hispanic, 3 Asian, 2 Other), and 0.5% (n=5) unknown race. Age distribution (mean 49.2 for White and 49.2 for Black) and node negative disease (White 68/403 (42%), Black 24/59 (41%)) were similar. However, tumor size ≤2cm was seen more commonly in White patients (34%, 137/403) compared with Black patients (20%, 12/59). Black patients had a higher proportion of high sTILs (≥30%) with 23.7% (14/59) compared to White patients (11.4%, 46/403). The association of continuous stromal TILs with DFS (hazard ratio for a 10-point difference) was 0.84 (95% CI 0.72, 0.98) for White patients and 0.94 (95% CI 0.73, 1.20) for Black patients [159 DFS events for Whites, 26 DFS events for Blacks]. Conclusions: This is the first dataset from prospective clinical trials evaluating sTILs in TNBC in Black patients. Prevalence of high sTILs was greater in Black patients compared to White patients. The association between increasing sTILs and improved invasive disease-free survival across racial/ethnic groups must be investigated in larger datasets. Table 1.Race/EthnicityTotal (n=481)White (n=403)Black (n=59)Other (n=19)Mean age49.049.249.245.6T1 (tumor <=2cm)157(32.6%)137 (34.0%)12 (20.3%)8 (42.1%)T2 (tumor >2 and <=5cm)283(58.8%)232 (57.6%)41 (69.5%)10 (52.6%)T3 and T441 (8.5%)34 (8.4%)6 (10.2%)1 (5.3%)Node negative197 (41.0%)168 (41.7%)24 (40.7%)5 (26.3%)Median sTILs (Quartiles)10 (10, 20)10 (10, 20)10 (10,20)20 (10, 30)sTILs = 095 (19.8%)83 (20.6%)10 (16.9%)2 (10.5%)sTILs 10-29%319 (66.3%)274 (68.0%)35 (59.3%)10 (52.6%)sTILs ≥30%67 (13.9%)46 (11.4%)14 (23.7%)7 (36.8%)—sTIL 30-49%,46 (9.6%)32 (7.9%)11 (18.6%)3 (15.8%)—sTIL 50-74%,17 (3.5%)11 (2.7%)3 (5.1%)3 (15.8%)—sTIL 75-100%4 (0.8%)3 (0.7%)01 (5.2%)iDFS (HR for 10% sTIL increase)0.86 (95% CI 0.76, 0.98)0.84 (95% CI 0.72, 0.98)0.94 (95% CI 0.73, 1.20)0.97 (95% CI 0.68, 1.40)DRFI (HR for 10% sTIL increase)0.82 (95% CI 0.68, 0.99)0.79 (95% CI 0.63, 1.00)1.08 (95% CI 0.82, 1.44)0.54 (95% CI 0.32, 0.90)OS (HR for 10% sTIL increase)0.81 (95% CI 0.69, 0.95)0.76 (95% CI 0.62, 0.94)1.01 (95% CI 0.76, 1.35)0.83 (95% CI 0.54, 1.29) Citation Format: Natalie Klar, Robert J Gray, Sylvia Adams, Joseph A Sparano, Lori J Goldstein, Angela M DeMichele, Antonio C Wolff, Nancy E Davidson, George W Sledge, Sunil S Badve. Stromal tumor infiltrating lymphocytes analysis by race and ethnicity in triple negative breast cancers from 2 phase III randomized adjuvant breast cancer trials: ECOG-ACRIN E2197 and E1199 [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-08-35.