Abstract GS2-07: Updated results from a phase 3 randomized clinical trial in participants (pts) with 1-3 positive lymph nodes (LN), hormone receptor-positive (HR+) and HER2-negative (HER2-) breast cancer (BC) with recurrence score (RS) ≤ 25 randomized to endocrine therapy (ET) +/- chemotherapy (CT): SWOG S1007 (RxPONDER)

• Published in: Cancer research (Chicago, Ill.) Ill.), 2022-02, Vol.82 (4_Supplement), p.GS2-07-GS2-07
• Main Authors: Kalinsky, Kevin M, Barlow, William E, Gralow, Julie R, Meric-Bernstam, Funda, Albain, Kathy S, Hayes, Daniel F, Lin, Nancy U, Perez, Edith A, Goldstein, Lori A, Chia, Stephen KL, Dhesy-Thind, Sukhbinder, Rastogi, Priya, Alba, Emilio, Delaloge, Suzette, Martin, Miguel, Kelly, Catherine M, Ruiz-Borrego, Manuel, Gil-Gil, Miguel, Arce-Salinas, Claudia H, Brain, Etienne GC, Lee, Eun Sook, Pierga, Jean-Yves, Bermejo, Begoña, Ramos-Vasquez, Manuel, Jung, Kyung Hae, Ferrero, Jean-Marc, Schott, Anne, Shak, Steven, Sharma, Priyanka, Lew, Danika, Miao, Jieling, Tripathy, Debasish, Pusztai, Lajos, Hortobagyi, Gabriel
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.SABCS21-GS2-07

Background: We previouslyreported that invasive disease-free survival (IDFS), the primary outcome, and distantdisease-free survival (DDFS), a secondary outcome, differed by menopausalstatus in a pre-specified analysis. Here,we report updates on IDFS and DDFS with additional follow-up, as well as distantrecurrence-free interval (DRFI) and post hoc analyses in premenopausal women.Methods: Eligibilitycriteria included women > 18 years of age with HR+, HER2-BC and 1-3 +LN and no contraindications to taxane and/or anthracycline basedCT. DRFI was defined as time to distant recurrence or death from breast cancer.Analyses were intent-to-treat among eligible pts. We performed a post hocanalysis evaluating IDFS between treatment arms in premenopausal pts with pN1mi.In addition, we conducted a two-year landmarked IDFS analysis by ovarianfunction suppression (OFS) or not in the ET arm, as well as by regularmenstrual periods or not in both treatment arms.Results: Among the 4,984eligible pts, there were 553 IDFS events and median follow-up of 6.1 years.Postmenopausal women do not have any IDFS or DDFS benefit with CT; however, 5-yearabsolute benefits for IDFS and DDFS with CT for premenopausal pts were 5.9% and3.3%, respectively. In pre-menopausal pts, CT was associated with improved DRFIfor all RS values < 25, with an absolute improvement of 2.3% for RS0-13 and of 2.8% for RS 14-25. Among premenopausal pts, 12.4% (n=206) had pNmi)disease. In a post hoc analysis, there was a trend for CT benefit for thosewith pNmi [hazard ratio (HR)=0.44, confidence interval (CI)=0.18-1.08]. Therewere only 22 IDFS events. Only 17.2% of premenopausal pts assigned to ETunderwent OFS in the first 24 months and in two-year landmarked analysis, therewas no IDFS difference in those who underwent OFS or not (HR=0.88,CI=0.47-1.63). In premenopausal women assigned to ET, 58.9% stopped havingperiods within the first 24 months, and have anumerically improved IDFS compared to those who continued regular periods (HR=1.48,CI: 0.92-2.40). Among premenopausal assigned to CT followed by ET, 80.8%stopped having periods within the first 24 months and have a numericallyimproved IDFS compared to those who continue to have regular periods (HR=1.56, CI:0.85-2.86).Discussion: In accordancewith the differential IDFS and DDFS benefit based upon menopausal status inS1007, premenopausal pts with 1-3+LN and RS < 25 had a statisticallysignificant improvement in DRFI with the addition of CT. A small proportion of S10