Abstract 242P
Background
NATALEE met its primary endpoint at second interim efficacy analysis with a significant invasive disease–free survival (iDFS) benefit with ribociclib (RIB) + nonsteroidal aromatase inhibitor (NSAI) vs NSAI in pts with HR+/HER2− EBC that was sustained with additional follow-up (median follow-up, 33.3 mo; HR, 0.749). We analyzed iDFS by prior systemic tx (chemotherapy [CT], endocrine therapy [ET]) in NATALEE using data from the final prespecified iDFS analysis (data cutoff: July 21, 2023).
Methods
Pts in NATALEE were randomized 1:1 to RIB 400 mg/d (3 wks on/1 wk off for 36 mo) + NSAI (≥60 mo) or NSAI. Men and premenopausal women also received goserelin. Pts were eligible if they had anatomic stage IIA (high-risk N0 or N1), IIB, or III EBC. Pts were included regardless of prior (neo)adjuvant CT. Pts starting ET ≤12 mo before randomization were included.
Results
Of 5101 pts included, 88% (4494/5101) received prior CT; 43% (2180/5101) had prior neoadjuvant CT, and 48% (2443/5101) had prior adjuvant CT. Of 1432 pts with N0 disease at diagnosis, most had prior CT (78%; 1113/1432). Most pts (73%) with prior neoadjuvant CT had stage III disease, while 19% with no prior CT had stage III disease (additional details in presentation). Overall, 69% (3496/5101) of pts received prior ET with median duration of last prior ET being 3.2 mo. An iDFS benefit with RIB + NSAI was observed regardless of prior CT (no CT, any CT, neoadjuvant, adjuvant) or duration of ET (Table). Table: 242P
iDFS by Prior CT and ET
| Prior tx, n (%) | RIB + NSAI n = 2549 | NSAI alone n = 2552 | HR (95% CI) |
| No prior CT | 300 (12) | 307 (12) | 0.82 (0.47-1.44) |
| Prior CT | 2249 (88) | 2245 (88) | 0.74 (0.62-0.89) |
| Prior neoadjuvant CT a | 1085 (43) | 1095 (43) | 0.82 (0.64-1.03) |
| Prior adjuvant CT a | 1223 (48) | 1220 (48) | 0.69 (0.52-0.92) |
| No prior ET | 793 (31) | 812 (32) | 0.77 (0.57-1.03) |
| Prior ET b | 1756 (69) | 1740 (68) | 0.74 (0.60-0.92) |
ET ConclusionsThis subgroup analysis demonstrated an iDFS benefit with RIB + NSAI vs NSAI alone in pts with HR+/HER2− EBC, regardless of duration of prior ET as well as prior (neo)adjuvant CT vs no CT, underlying potential role of CDK4/6 inhibitors in therapeutic de-escalation of CT in EBC. A majority of pts with N0 disease at diagnosis had received prior (neo)adjuvant CT, highlighting that these pts had a risk of recurrence that was considered high enough to warrant CT. Clinical trial identificationNCT03701334. Editorial acknowledgementEditorial assistance in the writing of the abstract was provided by Lize Greyling of Nucleus Global. Legal entity responsible for the studyNovartis Pharmaceuticals Corporation. FundingNovartis Pharmaceuticals Corporation. DisclosureN.P. McAndrew: Financial Interests, Personal, Advisory Board, US Medical Breast Cancer Steering Committee: AstraZeneca; Financial Interests, Personal, Advisory Board, Consulting: Novartis; Financial Interests, Personal, Writing Engagement, Consulting Retainer: GoodRx; Financial Interests, Institutional, Local PI: Daiichi Sankyo, Novartis, Dizal Pharmaceuticals, Arvinas, Loxo, AstraZeneca, Seattle Genetics, Mersana. S. Chia: Financial Interests, Personal and Institutional, Advisory Board, Advisory Board. My institution received funds for participation in clinical trials by Novartis.: Novartis Pharmaceuticals Corporation; Financial Interests, Personal and Institutional, Advisory Board, Advisory Board. My institution received funds for participation in clinical trials by Pfizer: Pfizer; Financial Interests, Personal and Institutional, Advisory Board, Advisory Board. My institution received funds for participation in clinical trials by Hoffamn LaRoche: Hoffman LaRoche; Financial Interests, Personal and Institutional, Advisory Board, Advisory Board. My institution received funds for participation in clinical trials by Eli Lilly.: Eli Lilly. A. Bardia: Financial Interests, Institutional, Advisory Board, Research Grant to Institution: Genentech, Novartis Pharmaceuticals Corporation, Pfizer, Merck, Sanofi, Radius Health, Immunomedics, Mersana. B. Xu: Financial Interests, Personal, Advisory Board, Advisory fees: Novartis Pharmaceuticals Corporation, AstraZeneca. K. Afenjar: Financial Interests, Institutional, Advisory Board, Translational Research In Oncology is contracted by Novartis as CRO conducting the NATALEE trial.: Novartis Pharmaceuticals Corporation. M. Akdere: Financial Interests, Institutional, Advisory Board, Employment and stock ownership: Novartis Pharmaceuticals Corporation. J.P. Zarate Gonzalez: Financial Interests, Institutional, Advisory Board, Employment and stock ownership: Novartis Pharmaceuticals Corporation. Y. Chattar: Financial Interests, Institutional, Advisory Board, Employment: Novartis Pharmaceuticals Corporation. P.A. Fasching: Financial Interests, Personal, Advisory Board, Advisory Board, Invited Speaker: Novartis Pharmaceuticals Corporation, Daiichi Sankyo, AstraZeneca, Eisai, Merck Sharp & Dohme, Lilly, Seagen, Roche; Financial Interests, Institutional, Funding, Institutional Funding: Biontech, Cepheid; Financial Interests, Personal, Advisory Board, Advisory Board, Invited Speaker, Research Grant: Pfizer; Financial Interests, Personal, Advisory Board, Advisory Board: Pierre Fabre, Hexal, Agendia. All other authors have declared no conflicts of interest. 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