Endocrine therapy synergizes with SMAC mimetics to potentiate antigen presentation and tumor regression in hormone receptor-positive breast cancer
- Cancer Res. 2023 Jul 14;CAN-23-1711. doi: 10.1158/0008-5472.CAN-23-1711.
- 1. Dana-Farber Cancer Institute, Boston, MA, United States.
- 2. Dana-Farber Cancer Institute, Boston, United States.
- 3. Dana-Farber/Harvard Cancer Center, Boston, MA, United States.
- 4. Dana-Farber/Harvard Cancer Center, Boston, United States.
- 5. Dana-Farber Cancer Institute, United States.
- 6. Huntsman Cancer Institute, United States.
- 7. Albert Einstein College of Medicine, Bronx, NY, United States.
- 8. Dana-Farber Cancer Institute, Boston, Ma, United States.
- 9. AbbVie (United States), North Chicago, IL, United States.
- 10. Central University Hospital of Asturias, Oviedo, Asturias, Spain.
- 11. Fox Chase Cancer Center, Philadelphia, PA, United States.
- 12. Sheba Medical Center, Ramat Gan, Israel.
- 13. Dana-Farber Cancer Institute, Boston, Massachusetts, United States.
- 14. Brigham and Women's Hospital, Boston, MA, United States.
- 15. The University of Texas MD Anderson Cancer Center, Houston, 77030, United States.
- 16. Harvard Medical School, Boston, MA, United States.
- 17. Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.
- 18. The University of Texas MD Anderson Cancer Center, Houston, TX, United States.
- 19. Sarah Cannon Research Center, Nashville, TN, United States.
- 20. AstraZeneca (United States), Gaithersburg, MD, United States.
- 21. Institute of Cancer Research, London, United Kingdom.
- 22. Royal Marsden Hospital, London, United Kingdom.
- 23. Huntsman Cancer Institute, Salt Lake City, UT, United States.
Immunotherapies have yet to demonstrate significant efficacy in the treatment of hormone receptor positive (HR+) breast Cancer. Given that endocrine therapy (ET) is the primary approach for treating HR+ breast Cancer, we investigated the effects of ET on the tumor immune microenvironment (TME) in HR+ breast Cancer. Spatial proteomics analysis of primary HR+ breast Cancer samples obtained at baseline and after ET from patients enrolled in a neoadjuvant clinical trial (NCT02764541) indicated that ET upregulated B2-microglobulin and influenced the TME in a manner that promotes enhanced immunogenicity. To gain a deeper understanding of the underlying mechanisms, the intrinsic effects of ET on Cancer cells were explored, which revealed that ET plays a crucial role in facilitating the chromatin binding of RelA, a key component of the NF-κB complex. Consequently, heightened NF-κB signaling enhanced the response to interferon-gamma, leading to the upregulation of β2-microglobulin and Other antigen presentation-related genes. Further, modulation of NF-κB signaling using a SMAC-mimetic in conjunction with ET augmented T-cell migration and enhanced MHC-I specific T-cell mediated cytotoxicity. Remarkably, the combination of ET and SMAC-mimetics, which also block pro-survival effects of NF-κB signaling through the degradation of inhibitors of Apoptosis (IAP) proteins, elicited tumor regression through cell-autonomous mechanisms, providing additional support for their combined use in HR+ breast Cancer.