Abstract P2-07-11: Application of the genetic signature MammaPrint™ in the Brazilian population - Real-world study (AGEMA-BRA)
Authors: Mansani Fabio Postiglione , Freitas-Junior Ruffo 
Published: March 2022

INTRODUCTION: The search for more personalized treatments for breast cancer patients has been increasingly frequent. In this sense, the search for the de-escalation of the therapies used, especially the cytotoxic ones, should be prioritized, with the application of genetic signatures, in patients with luminal tumors, allowing more adjusted therapies and avoiding serious and even fatal outcomes in patients who will not benefit from chemotherapy. The MINDACT study evaluated the use of MammaPrint™, but in a population of nine exclusively European countries. The study of the application of this genetic signature in other populations, especially in low- and middle-income countries, may determine greater safety in the universalization of the test.OBJECTIVE: To analyze the results of the application of MammaPrint™ in the Brazilian population, and to compare with data from the MINDACT study, when applied to breast cancer patients with high clinical risk.METHODOLOGY: Cross-sectional study comparing the prevalence of low and high genomic risk in a population with breast carcinoma, of high clinical risk, in the populations of the MINDACT study and of a Brazilian cohort, evaluated by the genetic signature MammaPrint™, between 2016 and 2020. The simple and relative frequencies of the variables were calculated in relation to the classification in low and high risk of the populations of the AGEMA-BRA and MINDACT studies. Then, the chi-square test was used to verify the differences between the proportions. To measure the intensity of differences/associations, relative risks (RR) and their 95% confidence intervals (95% CI) were calculated. The tests were considered significant when p&lt;0.05.RESULTS: The presence of the signature of 70 genes with low genomic risk in the total AGEMA-BRA sample was found in 57.1% (542 patients), compared with 46.2% in the MINDACT study (RR 1.23 (1.16-1.32 p &lt;0,001). In the analysis of subgroup by age group; &lt;35 years in 46.4% (13 patients), 35-49 years in 53.4% (151 patients), 50-70 years in 59.2% (321 patients), &gt;70 years in 60.7% (54 patients), compared with the MINDACT study where they were found respectively 24 % (RR 1.97 (1.13-3.43 p= 0.038), 44.1% (RR 1.20 (1.06-1.37 p= 0.006), 48.1% (RR 1.23 p &lt;0,001), 61.5%. (RR 0.98 (0.69-1.39) p= 0.936). When assessed according to menopausal status, the low genomic risk represented 52.7% (164 patients, 43% in MINDACT, RR 1.23 (1.09-1.39 p =0.002)) in premenopausal and 59.3% (375 patients, 48% in MINDACT, RR 1.23(1.14-1.33) p &lt;0,001) postmenopausal.CONCLUSION: The evaluation of the results of the AGEMA-BRA study, when compared to the MINDACT study, demonstrated a higher prevalence of patients with low genomic risk in all age groups (except &gt;70 years), indicating that the possibility of treatment de-escalation is even more significant in the Brazilian population than in the European population. Evaluation of outcomes regarding relapse-free survival and overall survival, an ongoing study, is necessary to confirm the data obtained.

LR (low genomic risk), HR (high genomic risk), RR (relative risk), CI (confidence interval)LRHRRRCIp. valorAllBRAZIL542 (57,.%)408 (42.9%)1.231.16-1.32&lt;0.001MINDACT1550 (46.2%)1806 (53.8%)&lt;35 yearsBRAZIL13 (46.4%)15 (53.6%)1.971.13-3.430.038MINDACT20 (23.5%)65 (76.5%)35-49 yearsBRAZIL151 (53,4%)132 (46,6%)1.201.06-1.370.006MINDACT514 (44.1%)651 (55.9%)50-70 yearsBRAZIL321 (59.2%)221 (40.8%)1.231.13-1.34&lt;0.001MINDACT1000 (48.1%)1080 (51.9%)&gt;70 yeartsBRAZIL54 (60.7%)35 (39.3%)0.980.69-1.390.936MINDACT16 (61.5%)10 (38.5%)PREMENOPAUSEBRAZIL164 (52.7%)147 (47.3%)1.231.09-1.390.002MINDACT534 (42.7%)716 (57.3%)POSTMENOPAUSEBRAZIL375 (59.4%)256 (40.6%)1.231.14-1.33&lt;0.001MINDACT1016 (48.2%)1090 (51,8%)

Citation Format: Fabio Postiglione Mansani, Ruffo Freitas-Junior. Application of the genetic signature MammaPrint™ in the Brazilian population - Real-world study (AGEMA-BRA) [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 P2-07-11.