Expanding Immunotherapy Use in Early-Stage Breast Cancer

During a conversation with CancerNetwork® at the 2025 International Congress on the Future of Breast Cancer East hosted by Physicians Education Resource LLC®, Heather McArthur, MD, spoke about the expanding role of immunotherapy in patients with early breast cancer.

McArthur referenced her presentation at the conference, noting that the role of immunotherapy, particularly for patients with triple-negative disease or HER2-positive subtypes, was currently being studied.¹ Her presentation also focused on the phase 3 KEYNOTE-522 trial (NCT03036488).²

In KEYNOTE-522, patients with untreated stage II or III triple-negative breast cancer were randomly assigned 2:1 to receive 4 cycles of neoadjuvant pembrolizumab (Keytruda) at 200 mg or placebo every 3 weeks plus paclitaxel and carboplatin followed by 4 cycles of pembrolizumab or placebo plus doxorubicin/cyclophosphamide or epirubicin/cyclophosphamide. Patients then went on to receive definitive surgery and were given adjuvant pembrolizumab or placebo every 3 weeks for 9 cycles.

The median follow-up was 75.1 months, and the estimated overall survival at 60 months was 86.6% (95% CI, 84.0%-88.8%) in the pembrolizumab group vs 81.7% (95% CI, 77.5%-85.2%) in the placebo group (P = .002).

McArthur is the clinical director of Breast Cancer and Komen Distinguished Chair in Clinical Breast Cancer Research at the University of Texas Southwestern Medical Center.

Transcript:

We outlined a number of ongoing studies, particularly studies that are combining immune therapy with a promising new category of antibody drug conjugates. We talked about studies that are ongoing, looking at patients who have high-risk residual disease after neoadjuvant therapy, being [randomly assigned] to the current standard of care, which is adjuvant immune therapy alone, vs immune therapy with one of these promising novel antibody drug conjugates. There are studies that are moving even earlier in the course of disease looking at antibody drug conjugates with immune therapy going head-to-head against the FDA-approved KEYNOTE-522 regimen, or part of the KEYNOTE-522 regimen.

References

1. McArthur H. Immunotherapy for high-risk early-stage breast cancer: who benefits? Presented at the 2025 International Congress on the Future of Breast Cancer East; July 11-12, 2025, New York, NY.
2. Schmid P, Cortes J, Dent R, et al. Overall survival with pembrolizumab in early-stage triple-negative breast cancer. N Engl J Med. 2024;391(21):1981-1991. doi:10.1056/NEJMoa2409932