A phase III trial evaluating addition of adjuvant chemotherapy to ovarian function suppression + endocrine therapy in premenopausal women with pN0-1, HR+/HER2– breast cancer and Oncotype recurrence score ≤ 25 (OFSET): NRG-BR009.

E Eleftherios P. Mamounas (AdventHealth Cancer Institute, Orlando, FL) G Gong Tang (NRG Oncology SDMC; Department of Biostatistics and Health Data Science, University of Pittsburgh, Pittsburgh, PA) S Shannon L. Puhalla (NSABP Foundation and UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, PA) S Sandra M. Swain (Georgetown Lombardi Comprehensive Cancer Center; Georgetown University Medical Center; and MedStar Health, Washington, DC) P Patricia A. Ganz (Department of Health Policy and Management UCLA Fielding School of Public Health Los Angeles California USA) N Norah Lynn Henry (University of Michigan Rogel Cancer Center, Ann Arbor, MI) R Reena S. Cecchini (NRG Oncology SDMC; Department of Biostatistics and Health Data Science, University of Pittsburgh, Pittsburgh, PA) S Sonya A. Reid (Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN) P Priya Rastogi (From the National Surgical Adjuvant Breast and Bowel Project (NSABP) Foundation (C.E.G., E.P.M., N.W., P.R., I.L.W., A.M.B.) and University of Pittsburgh School of Medicine–UPMC Hillman Cancer Center (C.E.G., N.W., P.R., A.M.B.) — both in Pittsburgh; AGO-B and Helios Klinikum Berlin–Buch, Berlin (M.U.), the National Center for Tumor Diseases, Heidelberg University Hospital, and German Cancer Research Center, Heidelberg (A.S.), Evangelische Kliniken Gelsenkirchen, Gelsenkirchen (H.H.F.), Arbeitsgemeinschaft Gynäkologische Onkologie–Breast and Sana Klinikum Offenbach, Offenbach (C.J.), the Department of Gynecology and Obstetrics, University Hospital Erlangen, Comprehensive Cancer Center Erlangen–EMN, Friedrich–Alexander University Erlangen–Nuremberg, Erlangen (P.A.F.), German Breast Group, Neu-Isenburg (P.W., S.L.), and the Center for Hematology and Oncology Bethanien, Goethe University, Frankfurt (S.L.) — all in Germany; National Taiwan University Hospital and National Taiwan University College of Medicine,...) C Charles E. Geyer (From the National Surgical Adjuvant Breast and Bowel Project (NSABP) Foundation (C.E.G., E.P.M., N.W., P.R., I.L.W., A.M.B.) and University of Pittsburgh School of Medicine–UPMC Hillman Cancer Center (C.E.G., N.W., P.R., A.M.B.) — both in Pittsburgh; AGO-B and Helios Klinikum Berlin–Buch, Berlin (M.U.), the National Center for Tumor Diseases, Heidelberg University Hospital, and German Cancer Research Center, Heidelberg (A.S.), Evangelische Kliniken Gelsenkirchen, Gelsenkirchen (H.H.F.), Arbeitsgemeinschaft Gynäkologische Onkologie–Breast and Sana Klinikum Offenbach, Offenbach (C.J.), the Department of Gynecology and Obstetrics, University Hospital Erlangen, Comprehensive Cancer Center Erlangen–EMN, Friedrich–Alexander University Erlangen–Nuremberg, Erlangen (P.A.F.), German Breast Group, Neu-Isenburg (P.W., S.L.), and the Center for Hematology and Oncology Bethanien, Goethe University, Frankfurt (S.L.) — all in Germany; National Taiwan University Hospital and National Taiwan University College of Medicine,...) J Julia R. White (University of Kansas Medical Center Comprehensive Cancer Center, Kansas City) A Amy Sanders Clark (Abramson Cancer Center of the University of Pennsylvania, Philadelphia, PA) T Tufia C. Haddad (Mayo Clinic Rochester, Rochester, MN) G Gregory A. Vidal (West Cancer Center and Research Institute, Germantown, TN) N Norman Wolmark (University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh)

Abstract

TPS650 Background: The TAILORx and RxPONDER trials showed that recurrence score (RS) identifies many postmenopausal pts who do not benefit from addition of ACT to endocrine therapy (ET); however, RS also identifies subsets who do benefit (node-neg/high clinical risk/RS 16-20, node-neg/RS 21-25, and node-pos/RS ≤25). Most premenopausal pts in these trials did not receive ovarian function suppression (OFS) as part of their ET regimen. Given the observed benefit from OFS in high-risk premenopausal pts with HR+/HER2– BC in SOFT/TEXT, we question whether the ACT benefit in TAILORx/RxPONDER was due to chemotherapy-induced OFS. To address this, we developed OFSET, a phase III clinical trial comparing OFS+ET to ACT+OFS+ET. Methods: We hypothesize that addition of ACT to OFS+ET is superior to OFS+ET in improving invasive breast cancer-free survival (IBCFS) among premenopausal pts with early-stage HR+/HER2– tumors, and a 21-gene RS between 16-25 (for pN0 pts) and 0-25 (for pN1 pts). Secondary objectives include invasive disease-free survival, overall survival, distant recurrence-free interval, breast cancer-free interval, and health-related quality of life (HRQOL). Pts must be node-neg with RS 16-20 (plus high clinical risk), RS 21-25, or have 1-3 positive nodes with RS ≤25. Stratification is by nodal status/RS status (pN0 RS 16-25; pN1 RS 0-15; pN1 RS 16-25), intent to receive CDK4/6 inhibitor (yes; no), and age (18-39; ≥40). Pts are randomized after surgery to either OFS+ET or ACT+OFS+ET. ET is an aromatase inhibitor (AI) per physician discretion; or tamoxifen if AI is not tolerated or if OFS is incomplete. Radiotherapy will be administered per protocol guidelines. An HRQOL sub-study will assess severe menopausal symptoms (measured by FACT ESS-19) and pain severity (PROMIS) between arms. Blood and tumor specimens will be collected for future research. We anticipate accrual of 3,960 pts in 7 yrs, 7 mos. Per NSABP B-28/RxPONDER data, 5-yr IBCFS of pN1 pts on the ACT+OFS+ET arm is estimated at 92.3%. Per TAILORx data, 5-yr IBCFS of pN0 pts on the ACT arm is ~95%. Assuming 56% of pts to be pN0 and 44% pN1, and a 0.5% annual loss-to-follow-up rate, the definitive analyses to detect a hazard ratio: 0.75 with ACT+OFS+ET v OFS+ET, with 1-sided α of 0.025 and 80% power, will require 380 IBCFS events, expected to occur ~11 yrs after study initiation. Accrual is 496/3,960 (from 8/2023 to 1/2026). NCT #: NCT05879926. Clinical trial information: NCT05879926 .

Article Details

Volume / Issue Vol. 44, Issue 16_suppl
Published June 01, 2026
ISSN 0732-183X
Publisher Lippincott Williams & Wilkins

Journal Info

Journal of Clinical Oncology

Lippincott Williams & Wilkins

ISSN: 0732-183X Health Sciences

Authors (15)

E

Eleftherios P. Mamounas

AdventHealth Cancer Institute, Orlando, FL

G

Gong Tang

NRG Oncology SDMC; Department of Biostatistics and Health Data Science, University of Pittsburgh, Pittsburgh, PA

S

Shannon L. Puhalla

NSABP Foundation and UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, PA

S

Sandra M. Swain

Georgetown Lombardi Comprehensive Cancer Center; Georgetown University Medical Center; and MedStar Health, Washington, DC

P

Patricia A. Ganz

Department of Health Policy and Management UCLA Fielding School of Public Health Los Angeles California USA

N

Norah Lynn Henry

University of Michigan Rogel Cancer Center, Ann Arbor, MI

R

Reena S. Cecchini

NRG Oncology SDMC; Department of Biostatistics and Health Data Science, University of Pittsburgh, Pittsburgh, PA

S

Sonya A. Reid

Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN

P

Priya Rastogi

From the National Surgical Adjuvant Breast and Bowel Project (NSABP) Foundation (C.E.G., E.P.M., N.W., P.R., I.L.W., A.M.B.) and University of Pittsburgh School of Medicine–UPMC Hillman Cancer Center (C.E.G., N.W., P.R., A.M.B.) — both in Pittsburgh; AGO-B and Helios Klinikum Berlin–Buch, Berlin (M.U.), the National Center for Tumor Diseases, Heidelberg University Hospital, and German Cancer Research Center, Heidelberg (A.S.), Evangelische Kliniken Gelsenkirchen, Gelsenkirchen (H.H.F.), Arbeitsgemeinschaft Gynäkologische Onkologie–Breast and Sana Klinikum Offenbach, Offenbach (C.J.), the Department of Gynecology and Obstetrics, University Hospital Erlangen, Comprehensive Cancer Center Erlangen–EMN, Friedrich–Alexander University Erlangen–Nuremberg, Erlangen (P.A.F.), German Breast Group, Neu-Isenburg (P.W., S.L.), and the Center for Hematology and Oncology Bethanien, Goethe University, Frankfurt (S.L.) — all in Germany; National Taiwan University Hospital and National Taiwan University College of Medicine,...

C

Charles E. Geyer

From the National Surgical Adjuvant Breast and Bowel Project (NSABP) Foundation (C.E.G., E.P.M., N.W., P.R., I.L.W., A.M.B.) and University of Pittsburgh School of Medicine–UPMC Hillman Cancer Center (C.E.G., N.W., P.R., A.M.B.) — both in Pittsburgh; AGO-B and Helios Klinikum Berlin–Buch, Berlin (M.U.), the National Center for Tumor Diseases, Heidelberg University Hospital, and German Cancer Research Center, Heidelberg (A.S.), Evangelische Kliniken Gelsenkirchen, Gelsenkirchen (H.H.F.), Arbeitsgemeinschaft Gynäkologische Onkologie–Breast and Sana Klinikum Offenbach, Offenbach (C.J.), the Department of Gynecology and Obstetrics, University Hospital Erlangen, Comprehensive Cancer Center Erlangen–EMN, Friedrich–Alexander University Erlangen–Nuremberg, Erlangen (P.A.F.), German Breast Group, Neu-Isenburg (P.W., S.L.), and the Center for Hematology and Oncology Bethanien, Goethe University, Frankfurt (S.L.) — all in Germany; National Taiwan University Hospital and National Taiwan University College of Medicine,...

J

Julia R. White

University of Kansas Medical Center Comprehensive Cancer Center, Kansas City

A

Amy Sanders Clark

Abramson Cancer Center of the University of Pennsylvania, Philadelphia, PA

T

Tufia C. Haddad

Mayo Clinic Rochester, Rochester, MN

G

Gregory A. Vidal

West Cancer Center and Research Institute, Germantown, TN

N

Norman Wolmark

University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh