December 2025

A Big Ten Cancer Research Consortium clinical trial, BTCRC-BRE15-024, titled “A phase I/II, single arm, nonrandomized study of ribociclib, a CDK 4/6 inhibitor, in combination with bicalutamide, an androgen receptor inhibitor, in advanced AR-positive triple-negative breast cancer,” (SABCS Poster # PS5-02-26) will be presented by Julia Knight-Shefner, MD, of the University of Wisconsin Carbone Cancer Center, as a poster at the 2025 San Antonio Breast Cancer Symposium.

BTCRC-BRE15-024 was led by Kari Wisinski, MD, of the University of Wisconsin Carbone Cancer Center, in collaboration with Ruth O’Regan, MD, now of the University of Rochester.

About PS5-02-26

Triple-negative breast cancer (TNBC) is a heterogeneous disease with limited treatment options for advanced cases. About 25% to 35% of TNBC cases express the androgen receptor, and preclinical evidence suggests the luminal androgen receptor subtype may be especially sensitive to CDK 4/6 inhibition. This study evaluated whether dual targeting of AR signaling and CDK 4/6 pathways using bicalutamide and ribociclib could provide clinical benefit in AR-positive TNBC.

A total of 21 patients were enrolled. The recommended phase II dose was 600 milligrams of ribociclib on days 1 through 21 of a 28-day cycle with 150 milligrams of bicalutamide daily. 6/12 patients treated with the RP2D of bicalutamide and ribociclib achieved disease control at 16 weeks with a median progression-free survival of 2.23 months and a clinical benefit rate of 50%. Safety findings aligned with the known profile of CDK 4/6 inhibition, with neutropenia, leukopenia, and lymphopenia reported most frequently. Exploratory circulating tumor cell analysis showed that AR splice variants ​were associated with both intrinsic and acquired treatment resistance.

Although the study closed early due to low accrual, the findings support continued investigation of biomarker-driven approaches for AR-positive TNBC. CTC-based signatures and other biomarkers beyond AR immunohistochemistry may help refine patient selection for therapies that target AR and CDK 4/6 pathways.

The study was conducted across several institutions, including the University of Wisconsin Carbone Cancer Center, the University of Rochester, the University of Illinois Cancer Center, and the University of Iowa Holden Comprehensive Cancer Center.

Authors of this abstract include J. Knight-Shefner, M.T. West, V. Carreno, I. Fernandez, K.B. Wisinski and M.N. Sharifi of the University of Wisconsin; R.M. O’Regan of the University of Rochester; E. Sampene of the University of Wisconsin; O. Danciu and K. Hoskins of the University of Illinois Cancer Center; and M.E. Burkard of the University of Iowa Holden Cancer Center.

View abstract: https://sabcs.org/events/poster-session-5/

Congratulations to all co-authors and study teams whose work contributed to these presentations.

About the Big Ten Cancer Research Consortium: The Big Ten Cancer Research Consortium was created in 2013 to transform the conduct of cancer research through collaborative clinical trials and observational studies that seek to improve the lives of cancer patients in the diverse communities we serve by leveraging the scientific and clinical expertise of Big Ten universities. The Big Ten Cancer Research Consortium creates a unique team research culture to drive science rapidly from ideas to treatment and prevention. Within this innovative environment, today’s research leaders collaborate with and mentor the research leaders of tomorrow. Since its founding, the Big Ten CRC has activated nearly 40 clinical trials across a wide range of cancer types, more than 1,000 participants have enrolled in Big Ten CRC studies, and more than 500 researchers have joined Big Ten CRC Clinical Trial Working Groups. 

About the Big Ten Conference: The Big Ten Conference is an association of world-class universities whose member institutions share a common mission of research, graduate, professional, and undergraduate teaching, and public service. Founded in 1896, the Big Ten has sustained a comprehensive set of shared practices and policies that enforce the priority of academics in the lives of students competing in intercollegiate athletics and emphasize the values of integrity, fairness, and competitiveness. The broad-based programs of the 18 Big Ten institutions provide direct financial support for more than 11,000 participation opportunities on 350 teams in 42 different sports. The Big Ten sponsors 28 official conference sports, 14 for men and 14 for women. For more information, visit www.bigten.org.