Back to Authors

Pierga, Jean‐Yves

https://orcid.org/0000-0002-2863-9995

Mayo Clinic

Université Paris Cité

Citations 5

Clinical Validity of Repeated Circulating Tumor Cell Enumeration as an Early Treatment Monitoring Tool for Metastatic Breast Cancer in the PREDICT Global Pooled Analysis
Janni, Wolfgang , Yab, Tracy C. , Cristofanilli, Massimo , Hayes, Daniel F. , Ignatiadis, Michail , Regan, Meredith M. , Alix‐Panabières, Catherine , Barlow, William E. , Gazzaniga, Paola , Gisbert‐Criado, Rafael , Jiang, Zefei , Magbanua, Mark Jesus M. , Mavroudis, Dimitriοs , Müller, Volkmar , Pierga, Jean‐Yves , Rack, Brigitte , Riethdorf, Sabine , Sleijfer, Stefan , Smerage, Jeffrey B. , Stebbing, Justin , Vidal-Martínez, José , Liu, Minetta C. , Friedl, Thomas W P , Yab, Tracy C , Bidard, Francois-Clément , Cristofanilli, Massimo , Hayes, Daniel F , Ignatiadis, Michail , Regan, Meredith M , Alix-Panabieres, Catherine , Barlow, William E , Caldas, Carlos , Carey, Lisa A , Dirix, Luc , Fehm, Tanja , García-Sáenz, José A , Gazzaniga, Paola , Generali, Daniele , Gerratana, Lorenzo , Gisbert-Criado, Rafael , Jacot, William , Jiang, Zefei , Joosse, Simon A , Lianidou, Evi , López López, Rafael , Magbanua, Mark J M , Manso Sanchez, Luis , Mavroudis, Dimitris , Müller, Volkmar , Munzone, Elisabetta , Pantel, Klaus , Pierga, Jean-Yves , Rack, Brigitte , Riethdorf, Sabine , Rugo, Hope S , Sideras, Kostandinos , Sleijfer, Stefan , Smerage, Jeffrey , Stebbing, Justin , Terstappen, Leon W M M , Vidal-Martínez, Jose , Wallwiener, Markus , Giridhar, Karthik V , Liu, Minetta , Caldas, Carlos , Carey, Lisa A. , Fehm, Tanja , García-Sáenz, José Á. , Joosse, Simon A. , Manso, Luís , Rugo, Hope S. , Sideras, Kostandinos , Terstappen, Leon W.M.M. , Giridhar, Karthik V.

Clinical Cancer Research | March 18, 2025 | Volume: 31 | Issue: 11 | Pages: 2196-2209

10.1158/1078-0432.ccr-24-3108 Get It

Abstract Purpose: The aim of PREDICT was to confirm clinical validity and the potential for clinical utility of serial circulating tumor cell (CTC) enumeration in patients with metastatic breast cancer, focusing on its prognostic value in different breast cancer subtypes and clinical settings. Experimental Design: In total, 4,436 individual patient-level data with CTC results from both baseline and one follow-up (CellSearch; Menarini Silicon Biosystems) were analyzed to evaluate the association between CTC detection and overall survival (OS) in the full patient cohort and separately for tumor and treatment types. Results: Using the cutoff ≥1 CTC for CTC positivity, 913 (20.6%) patients had 0 CTCs at both time points (neg/neg) and 325 (7.3%) and 1,189 (26.8%) patients converted from CTC negative to CTC positive (neg/pos) or vice versa (pos/neg), whereas 2,009 (45.3%) patients had at least one CTC at both time points (pos/pos). The median OS for the neg/neg, neg/pos, pos/neg, and pos/pos group was 45.6, 26.1, 32.3, and 17.3 months, respectively (P < 0.0001, global log-rank test). CTC responders (pos/neg) showed a lower risk of death compared with CTC nonresponders (pos/pos; HR, 0.48; 95% confidence interval, 0.44–0.53). Similar results were obtained in subgroup analyses according to hormone receptor and HER2 subtype, treatment type, and with a ≥5 CTC cutoff for CTC positivity. Conclusions: Follow-up CTC assessments strongly predict OS independently from tumor subtype and treatment. New randomized trials to define the clinical utility of CTC monitoring for risk stratification and as an early response marker in metastatic breast cancer are urgently needed.
Imlunestrant, an Oral Selective Estrogen Receptor Degrader, as Monotherapy and in Combination With Targeted Therapy in Estrogen Receptor–Positive, Human Epidermal Growth Factor Receptor 2–Negative Advanced Breast Cancer: Phase Ia/Ib EMBER Study
Jhaveri, Komal , Lim, Elgene , Jeselsohn, Rinath , Cynthia, X. , Hamilton, Erika , Osborne, Cynthia R. , Bhave, Manali Ajay, Kaufman, Peter A. , Beck, J. Thaddeus , Manso, Luís , Parajuli, Ritesh , Wang, Hwei-Chung, Tao, Jessica J. , Harnden, Kathleen , Yonemori, Kan , Dhakal, Ajay , Neven, Patrick , Aftimos, Philippe , Pierga, Jean‐Yves , Lu, Yen‐Shen , Larson, Timothy , Jerez, Yolanda , Sohn, Joohyuk , Saura, Cristina , Bardia, Aditya , Sammons, Sarah , Bacchion, Francesca , Li, Yujia , Estrem, Shawn T. , Nguyen, Bastien , Ismail‐Khan, Roohi , Smyth, Lillian M. , Beeram, Muralidhar , Jhaveri, Komal L , Ma, Cynthia , Hamilton, Erika P , Manso Sanchez, Luis , Im, Seock-Ah , Harnden, Kathleen , Yonemori, Kan , Dhakal, Ajay , Neven, Patrick , Aftimos, Philippe , Pierga, Jean-Yves , Lu, Yen-Shen , Larson, Timothy , Sideras, Kostandinos , Sohn, Joohyuk , Kim, Sung-Bae , Saura, Cristina , Bardia, Aditya , Sammons, Sarah L , Li, Yujia , Nguyen, Bastien , Ismail-Khan, Roohi , Smyth, Lillian , Beck, Joseph T , Im, Seock‐Ah , Sideras, Kostandinos , Yuen, Eunice , Rodrik-Outmezguine, Vanessa S.

Journal of Clinical Oncology | September 6, 2024 | Volume: 42 | Issue: 35 | Pages: 4173-4186

10.1200/jco.23.02733 Get It

PURPOSE Imlunestrant is a next-generation oral selective estrogen receptor (ER) degrader designed to deliver continuous ER target inhibition, including in ESR1- mutant breast cancer. This phase Ia/b trial determined the recommended phase II dose (RP2D), safety, pharmacokinetics, and efficacy of imlunestrant, as monotherapy and in combination with targeted therapy, in ER-positive (ER+) advanced breast cancer (ABC) and endometrial endometrioid cancer. The ER+/human epidermal growth factor receptor 2–negative (HER2–) ABC experience is reported here. METHODS An i3+3 dose-escalation design was used, followed by dose expansions of imlunestrant as monotherapy or in combination with abemaciclib with or without aromatase inhibitor (AI), everolimus, or alpelisib. Imlunestrant was administered orally once daily and with the combination partner per label. RESULTS Overall, 262 patients with ER+/HER2– ABC were treated (phase Ia, n = 74; phase Ib, n = 188). Among patients who received imlunestrant monotherapy (n = 114), no dose-limiting toxicities or discontinuations occurred. At the RP2D (400 mg once daily), patients (n = 51) reported grade 1-2 nausea (39.2%), fatigue (39.2%), and diarrhea (29.4%). Patients at RP2D had received previous cyclin-dependent kinase 4/6 inhibitor (CDK4/6i; 92.2%), fulvestrant (41.2%), and chemotherapy (29.4%) for ABC and achieved a median progression-free survival (mPFS) of 7.2 months (95% CI, 3.7 to 8.3). Among patients who received imlunestrant + abemaciclib (n = 42) and imlunestrant + abemaciclib + AI (n = 43), most (69.4%) were treatment-naïve for ABC; all were CDK4/6i-naïve. Patients treated with imlunestrant + everolimus (n = 42)/alpelisib (n = 21) had received previous CDK4/6i (100%), fulvestrant (34.9%), and chemotherapy (17.5%) for ABC. No new safety signals or interactions with partnered drugs were observed. The mPFS was 19.2 months (95% CI, 13.8 to not available) for imlunestrant + abemaciclib and was not reached for imlunestrant + abemaciclib + AI. The mPFS with imlunestrant + everolimus/alpelisib was 15.9 months (95% CI, 11.3 to 19.1)/9.2 months (95% CI, 3.7 to 11.1). Antitumor activity was evident regardless of ESR1 mutation status. CONCLUSION Imlunestrant, as monotherapy or in combination with targeted therapy, had a manageable safety profile with evidence of preliminary antitumor activity in ER+/HER2– ABC.
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 e
Albain, Kathy S. , Hayes, Daniel F. , Perez, Edith A. , Goldstein, Lori A, Chia, Stephen , Dhesy‐Thind, Sukhbinder , Rastogi, Priya , Ruíz‐Borrego, Manuel, Arce-Salinas, Claudia , Pierga, Jean‐Yves , Ramos-Vasquez, Manuel, Ferrero, Jean-­Marc , Schott, Anne F. , Shak, Steven , Lew, Danika L., Tripathy, Debasish , Hortobagyi, Gabriel, Dhesy-Thind, Sukhbinder , Kalinsky, Kevin M. , Barlow, William E. , Gralow, Julie R. , Meric‐Bernstam, Funda , Lin, Nancy U. , Alba, Emilio , Delaloge, Suzette , Martı́n, Miguel , Kelly, Catherine M. , Gil‐Gil, Miguel , Brain, Etienne G.C. , Lee, Eun Sook , Bermejo, Begoña , Jung, Kyung Hae , Sharma, Priyanka , Miao, Jieling , Pusztai, Lajos , Hortobágyi, Gabriel N.

Cancer Research | March 8, 2022 | Volume: 82 | Issue: 4_Supplement | Pages: GS2-07-GS2-07

10.1158/1538-7445.sabcs21-gs2-07 Get It

Abstract 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 S1007premenopausal participants underwent OFS. The role of OFS as it relates to CTbenefit cannot be determined from this study. A future randomized trial should address the clinical question if OFScan replace CT in premenopausal pts with HR+/HER2-, node-positive breast cancer.Funding: Supported by National Cancer Institute grants U10CA180888, U10CA180819,U10CA180820, U10CA180821, U10CA180868, U10CA180863, and in part by Susan G.Komen for the Cure® Research Program, The Hope Foundation for Cancer Research,Breast Cancer Research Foundation, and Genomic Health, Inc. Citation Format: Kevin M Kalinsky, William E Barlow, Julie R Gralow, Funda Meric-Bernstam, Kathy S Albain, Daniel F Hayes, Nancy U Lin, Edith A Perez, Lori A Goldstein, Stephen KL Chia, Sukhbinder Dhesy-Thind, Priya Rastogi, Emilio Alba, Suzette Delaloge, Miguel Martin, Catherine M Kelly, Manuel Ruiz-Borrego, Miguel Gil-Gil, Claudia H Arce-Salinas, Etienne GC Brain, Eun Sook Lee, Jean-Yves Pierga, Begoña Bermejo, Manuel Ramos-Vasquez, Kyung Hae Jung, Jean-Marc Ferrero, Anne Schott, Steven Shak, Priyanka Sharma, Danika Lew, Jieling Miao, Debasish Tripathy, Lajos Pusztai, Gabriel Hortobagyi. 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) [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 GS2-07.
Abstract GS4-08: Clinical utility of repeated circulating tumor cell (CTC) enumeration as early treatment monitoring tool in metastatic breast cancer (MBC) - a global pooled analysis with individual patient data
Janni, Wolfgang , Yab, Tracy C. , Hayes, Daniel F. , Regan, Meredith M. , Dirix, Luc , Gazzaniga, Paola , Gisbert‐Criado, Rafael , Jiang, Zefei , Magbanua, Mark Jesus M. , Mavroudis, Dimitriοs , Müller, Volkmar , Pierga, Jean‐Yves , Rack, Brigitte , Riethdorf, Sabine , Sleijfer, Stefan , Smerage, Jeffrey B. , Liu, Minetta C. , Gisbert-Criado, Rafael , Cristofanilli, Massimo , Bidard, Francois-Clément , Ignatiadis, Michail , Alix‐Panabières, Catherine , Barlow, William E. , Caldas, Carlos , Carey, Lisa A. , Fehm, Tanja , García-Sáenz, José Á. , Generali, Daniele , Gerratana, Lorenzo , Jacot, William , Lianidou, Evi , Manso, Luís , Munzone, Elisabetta , Pantel, Klaus , Rugo, Hope S. , Sideras, Kostandinos , Stebbing, Justin , Terstappen, Leon W.M.M. , Vidal-Martínez, José , Zamarchi, Rita , Giridhar, Karthik V. , Friedl, Thomas W P

Cancer Research | February 15, 2021 | Volume: 81 | Issue: 4_Supplement | Pages: GS4-08-GS4-08

10.1158/1538-7445.sabcs20-gs4-08 Get It

Abstract Background: Several studies suggest clinical utility of serial circulating tumor cell (CTC) enumeration as a means of assessing response status in metastatic breast cancer (MBC). The aim of this study is to conduct a comprehensive pooled analysis comprising globally available data to further define and explore the role of CTC enumeration as a tool for early treatment monitoring in patients with MBC with a focus on the predictive power in different breast cancer subtypes and clinical settings. Methods: In a global effort, peer-reviewed published studies with data on repeated CTC assessments (CellSearch® technology; Menarini Silicon Biosystems; Bologna, Italy) in MBC patients were screened and investigators were asked to provide individual patient data for this pooled analysis. 2761 cases from 32 data sets with data on both baseline and one follow up CTC assessments were included in the analysis (median time interval between the two CTC assessments 35 days). Data were analyzed using log rank tests and Cox regressions to evaluate the association between serial CTC enumeration results and overall survival (OS) in the full patient cohort and defined subgroups. Results: 588 (21.3%) patients had no CTCs at both time points (neg/neg), 236 (8.5%) patients were CTC negative at baseline and CTC positive at follow up (neg/pos), 712 (25.8%) patients converted from CTC positive at baseline to CTC negative (pos/neg), and 1225 (44.4%) patients had at least one CTC at both time points (pos/pos). Log rank tests showed significant differences in OS between these four CTC change groups (p < 0.0001 for all pairwise comparisons except for the comparison between neg/pos and pos/neg, p = 0.015). Median OS for the neg/neg, neg/pos, pos/neg and pos/pos group was 45.6, 26.1, 34.6, and 17.6 months, respectively. Hazard ratios (HR) (reference group neg/neg) were 1.38 (95% CI 1.16 - 1.64) for the pos/neg group, 1.78 (95% CI 1.43 - 2.22) for the neg/pos group, and 3.06 (95% CI 2.63 - 3.56) for the pos/pos group. Results were similar if a cutoff of 5 CTCs was used for CTC positivity (pos/neg group: HR 1.43, 95% CI 1.25 - 1.63; neg/pos group: HR 2.39, 95% CI 1.91 - 2.99; pos/pos group: HR 3.54, 95% CI 3.12 - 4.02). In total, 2586 patients could be assigned to different tumor subtypes based on known hormone receptor (ER) and HER2 status of the primary tumor: 1513 (58.5%) patients had a luminal-like tumor (ER positive, HER2 negative), 682 (26.4%) patients had a HER2-positive tumor, and 391 (15.1%) patients had a triple-negative tumor. In patients with luminal-like tumors, the hazard ratios were 1.67 (95% CI 1.29 - 2.17), 2.01 (95% CI 1.45 - 2.77), and 3.87 (95% CI 3.09 - 4.83) for the pos/neg, neg/pos, and pos/pos group, respectively. In patients with HER2-positive tumors, the neg/pos group (HR 1.68, 95% CI 1.12 - 2.53) and the pos/pos group (HR 2.11, 95% CI 1.58 - 2.83) showed significantly worse OS compared to the neg/neg group, while in triple-negative patients, the pos/pos group had a significantly shorter OS compared to the neg/neg group (HR 2.99, 95% CI 2.11 - 4.24). The results will be up-dated by inclusion of additional large data sets (CALGB 40502, CALGB 40503, COMET, SWOG S0500, TBCRC 001) for the analysis to be presented at SABCS 2020. Conclusion: This large pooled analysis confirms that at a median of 35 days after treatment initiation, follow-up CTC assessments strongly predict overall survival. These results suggest potential clinical utility of CTC monitoring as early response marker in MBC, especially in luminal-like tumors. Citation Format: Wolfgang J Janni, Tracy C. Yab, Daniel F. Hayes, Massimo Cristofanilli, Francois-Clement Bidard, Michail Ignatiadis, Meredith M. Regan, Catherine Alix-Panabières, William E. Barlow, Carlos Caldas, Lisa A. Carey, Luc Dirix, Tanja Fehm, Jose A. Garcia-Saenz, Paola Gazzaniga, Daniele Generali, Lorenzo Gerratana, Rafael Gisbert-Criado, William Jacot, Zefei Jiang, Evi Lianidou, Mark J.M. Magbanua, Luis Manso, Dimitrios Mavroudis, Volkmar Müller, Elisabetta Munzone, Klaus Pantel, Jean-Yves Pierga, Brigitte Rack, Sabine Riethdorf, Hope S. Rugo, Kostandinos Sideras, Stefan Sleijfer, Jeffrey Smerage, Justin Stebbing, Leon W.M.M. Terstappen, José Vidal-Martínez, Rita Zamarchi, Karthik Giridhar, Thomas W.P. Friedl, Minetta C. Liu. Clinical utility of repeated circulating tumor cell (CTC) enumeration as early treatment monitoring tool in metastatic breast cancer (MBC) - a global pooled analysis with individual patient data [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr GS4-08.
Abstract GS3-00: First results from a phase III randomized clinical trial of standard adjuvant endocrine therapy (ET) +/- chemotherapy (CT) in patients (pts) with 1-3 positive nodes, hormone receptor-positive (HR+) and HER2-negative (HER2-) breast cancer (
Albain, Kathy S. , Hayes, Daniel F. , Perez, Edith A. , Goldstein, Lori J. , Chia, Stephen , Dhesy-Thind, Subkhbinder, Rastogi, Priya , Gil, Miguel Gil, Arce-Salinas, Claudia , Pierga, Jean‐Yves , Lluch, Ana Hernandez, Vasquez, Manuel Ramos, Borrego, Manuel Ruíz, Ferrero, Jean-­Marc , Schott, Anne F. , Shak, S., Lew, Danika L., Miao, Jieling, Dhesy‐Thind, Sukhbinder , Dhesy-Thind, Sukhbinder , Kalinsky, Kevin M. , Barlow, William E. , Meric‐Bernstam, Funda , Gralow, Julie R. , Lin, Nancy U. , Alba, Emilio , Delaloge, Suzette , Martín, Miguel , Brain, Etienne G.C. , Park, In Hae , Jung, Kyung Hae , Sharma, Priyanka , Miao, Jieling , Tripathy, Debu , Hortobágyi, Gabriel N. , Pusztai, Lajos

Cancer Research | February 15, 2021 | Volume: 81 | Issue: 4_Supplement | Pages: GS3-00-GS3-00

10.1158/1538-7445.sabcs20-gs3-00 Get It

Abstract Funding: Supported by National Cancer Institute grants U10CA180888, U10CA180819, U10CA180820, U10CA180821, U10CA180868, U10CA180863; and in part by Susan G. Komen for the Cure® Research Program, The Hope Foundation for Cancer Research, Breast Cancer Research Foundation, and Genomic Health, Inc. Acknowledgement: The authors wish to thank Dr. Ana M. Gonzalez-Angulo, MD, for her invaluable contributions to the design and implementation of this study. Background: The clinical utility of the RS to determine CT benefit is well established in pts with HR+, HER2-, axillary lymph node (LN)-negative BC. Retrospective analyses from SWOG S8814 support the potential prognostic and predictive role of RS for CT benefit in postmenopausal pts with LN+ BC. SWOG S1007 is a prospective, randomized trial of endocrine therapy (ET) vs. chemoendocrine therapy (CET) in women with 1-3 +LN and a RS < 25 (NCT01272037). Methods: Eligibility criteria included women > 18 years of age with HR+, HER2- BC and 1-3 +LN and no contraindications to taxane and/or anthracycline based CT. Women with a RS < 25 were randomized to receive ET or CET in 1:1 randomization using 3 stratification factors: (1) RS (0-13 vs.14-25); (2) menopausal status; and (3) axillary nodal dissection vs. sentinel node biopsy. The primary objective was to determine the effect of CT on invasive disease-free survival (IDFS) and whether the effect depended on the RS. The primary analysis was to test for a significant interaction of the treatment arm and continuous RS using a Cox regression model for IDFS, adjusting for treatment, RS, and menopausal status. A total of 832 IDFS events were expected for the final analysis. Secondary objectives included overall survival (OS). The protocol specified that interaction between treatment and the stratification variables was to be tested and, if significant, separate analyses performed by stratum. Annual interim analyses were planned starting at 24% of events. At the third interim analysis with 410 IDFS events, the Data and Safety Monitoring Committee recommended reporting results, with a decision by the NCI’s Cancer Therapy Evaluation Program, the study sponsor. Results: Of the 9,383 women screened from 2/28/11-9/29/17, 5,083 pts (54.2%) were randomized. With a median follow-up of 5.1 years, 447 IDFS events have been observed. For the primary analysis, the interaction test for CT benefit and continuous RS was not statistically significant, p=0.30. In a model with CT, RS, and menopausal status (no interaction term), higher continuous RS was associated with worse IDFS [HR 1.06, 2-sided p<0.001, 95% Confidence Interval (CI) 1.04-1.07], and CT was associated with an improvement in IDFS (HR 0.81, p=0.026, 95% CI 0.67-0.98). In a pre-specified analysis, a significant interaction was identified between CT and menopausal status (p=0.004), necessitating separate analyses by menopausal status. In postmenopausal pts (N=3350, 67%), adjusting for continuous RS, the HR for CET vs. ET was not significant (HR=0.97, p=0.82, 95% CI 0.78-1.22; 5-year IDFS 91.6% vs. 91.9%) indicating no benefit from CT. In premenopausal pts (N=1665, 33%), the HR (0.54) was statistically significant (p=0.0004, 95% CI 0.38-0.76; 5-year IDFS 94.2% vs. 89.0%), indicating CT benefit. In premenopausal pts, ovarian suppression was performed in 15.9% vs. 3.7% (ET vs. CET), and 47.9% vs. 26.4% reported menstruation after 6 months of treatment. Although the number of events is limited, the HR for treatment adjusted by RS for OS in premenopausal pts was 0.47 (p=0.032, 95% CI 0.24-0.94). At this time, there is no differential effect with CT in regard to other stratification factors. Conclusions: There is a significant differential treatment effect of CT benefit based on RS for premenopausal vs. postmenopausal women requiring separate analyses. While only 54% of the protocol specified events are recorded and pts will be followed for 15 years, the current data show that adjuvant therapy can be de-escalated to ET alone in postmenopausal pts with a RS < 25 and 1-3 +LN. However, there is a strong IDFS benefit for CET in premenopausal pts, with an early indication of an OS improvement. Citation Format: Kevin Kalinsky, William E Barlow, Funda Meric-Bernstam, Julie R Gralow, Kathy S Albain, Daniel Hayes, Nancy Lin, Edith A Perez, Lori J Goldstein, Stephen Chia, Subkhbinder Dhesy-Thind, Priya Rastogi, Emilio Alba, Suzette Delaloge, Miguel Martín, Miguel Gil Gil, Claudia Arce-Salinas, Etienne Brain, In Hae Park, Jean-Yves Pierga, Ana Hernandez Lluch, Manuel Ramos Vasquez, Manuel Ruiz Borrego, Kyung Hae Jung, Jean-Marc Ferrero, Anne Schott, Steve Shak, Priyanka Sharma, Danika L Lew, Jieling Miao, Debu Tripathy, Gabriel Hortobagyi, Lajos Pusztai. First results from a phase III randomized clinical trial of standard adjuvant endocrine therapy (ET) +/- chemotherapy (CT) in patients (pts) with 1-3 positive nodes, hormone receptor-positive (HR+) and HER2-negative (HER2-) breast cancer (BC) with recurrence score (RS) < 25: SWOG S1007 (RxPonder) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr GS3-00.