Abstract PO5-02-03: Does the recommendation of adjuvant CDK4/6 inhibitors implicate more ovarian suppression in premenopausal patients? A real-world study of a public and a private Argentinean institution

Abstract

Abstract Introduction The recently published NATALEE trial has reported an increase of invasive disease free survival with the addition of ribociclib to hormone therapy during 3 years. Given the fact that aromatase inhibitors are required as the endocrine therapy backbone, premenopausal patients require ovarian function suppression (OFS) during CDKi treatment In the era of CDKi in the adjuvant setting, we hypothesize that the recommendation of GnRh analogs administration in addition to aromatase inhibitors will increase for premenopausal patients, given the inclusion criteria of this pivotal trial. For this reason, we explored in a retrospective cohort of a public and a private Argentinean institution to define whether the application of these criteria would imply an increase of the recommendation of OFS as part of the adjuvant endocrine treatment. Methods This was a multicentric retrospective cohort comprising premenopausal patients with early breast cancer diagnosis. Descriptive statistics were used to summarize data. The criteria for defining ribociclib recommendations were based on the phase III NATALEE clinical trial. Univariate analysis, including t and chi-square tests were used to determine differences between the populations that received and did not receive OFS, and between both participating institutions. p< 0,05 was considered to evaluate statistical significance. Results 191 premenopausal patients were incorporated in our analysis, and 48 (25.1%) received OFS. In this subgroup, mean age was lower (38.1 vs 44.2 years; p< 0.001) and the incidence of T3 (23.9 vs 6.5%; p=0.002), node-positive tumors (57.4 vs 28.9%; p=0.005), and prior chemotherapy treatment (75.5 vs 58.8%; p< 0.001) was higher. Among the 143 patients that did not receive OFS, 121 (84.6%) would have fulfilled clinical trial criteria for receiving ribociclib. No differences were observed according to the treating institution: 80.3 vs 87.8%; (p=0.22). The patient subgroup that would have met NATALEE criteria and did not receive OFS, had median age of 44.19 (SD 4.18), and had prior chemotherapy in 63.8% of the cases. Considering these characteristics, we observed that chemotherapy-induced amenorrhea and local institutional guidelines were the main explanations to understand why these moderate and high-risk patients did not receive OFS. Conclusion We observed that in premenopausal patients, the application of NATALEE criteria would result in an increase of the recommendation of GnRh analogues in around 80% of patients that had not received OFS in a retrospective cohort. This scenario may result in new challenges in treatment adherence and quality of life. In addition, this information is of special importance to carefully analyze the financial toxicity of a modern adjuvant approach that will be applied in a high proportion of eBC patients, especially in low and middle-income countries. Citation Format: Vanesa Lopez, Dana Narvaez, Jorge Nadal, Federico Waisberg, Adrian Nervo, Victoria Costanzo, Claudio Paletta, Fernando E. Petracci, Sergio Rivero, Alexis Ostinelli, Matías Chacón, Andrea Aguilar, Alejandro Kuzminin, Ageles Nico, Evelina Rovera, Naima Kassis, Maria Zapata Camaño, Carolina Almada, Maria Savignano, Gustavo Roganovich, Maria Eugenia Azar, Valeria Caceres. Does the recommendation of adjuvant CDK4/6 inhibitors implicate more ovarian suppression in premenopausal patients? A real-world study of a public and a private Argentinean institution [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 PO5-02-03.