Bria-IMT Plus Checkpoint Inhibition Leads to 52% 1-Year OS Rate in Heavily Pretreated Metastatic Breast Cancer

Treatment with the allogeneic, granulocyte macrophage colony-stimulating factor–secreting vaccine Bria-IMT (SV-BR-1-GM) in combination with immune checkpoint inhibition led to a 1-year overall survival (OS) rate of 52% in patients with heavily pretreated metastatic breast cancer, according to updated data from a phase 2 trial (NCT03328026).¹

This OS rate was achieved in 25 patients with metastatic breast cancer who were treated with the phase 3 formulation of Bria-IMT since 2022. Patients in this group had received a median of 6 prior lines of therapy, and this population included patients with hormone receptor–positive breast cancer (61%), HER2-positive breast cancer (6%), and triple-negative breast cancer (TNBC; 33%).

“Many patients with metastatic breast cancer unfortunately have disease progression despite treatment with checkpoint inhibitors and antibody-drug conjugates,” Aditya Bardia, MD, MPH, FASCO, a professor in the Department of Medicine of the Division of Hematology/Oncology, director of Translational Research Integration, and a member of Signal Transduction and Therapeutics at UCLA Health, stated in a news release. “[The] survival data in [this] single-arm phase 2 trial highlight the potential activity of Bria-IMT in combination with checkpoint inhibitors and is subject to ongoing investigation in a phase 3 randomized clinical trial [NCT06072612] in metastatic breast cancer.”

Previously reported findings from the phase 2 trial showed that treated patients with HR-positive breast cancer (n = 25) achieved a median OS of 17.3 months.² BriaCell Therapeutics cited a historical median OS of 14.4 months for sacituzumab govitecan-hziy (Trodelvy) and 11.3 months for single-agent chemotherapy.

Additionally, in the TNBC subgroup, Bria-IMT plus pembrolizumab yielded a median OS of 11.4 months compared with 11.8 months with the historical control for sacituzumab govitecan and 6.9 months for single-agent chemotherapy.

Phase 2 Trial Overview

Investigators of phase 2 trial enrolled patients at least 18 years of age with histologically confirmed recurrent or metastatic breast cancer whose disease had progressed on prior therapy.³

Patients with metastatic HR-positive, HER2-positive disease were required to be refractory to hormonal therapy and previously treated with at least 2 regimens including at least 2 anti-HER2 agents. Those with HR-positive, HER2-negative breast cancer needed to be refractory to hormonal therapy and previously treated with at least 2 chemotherapy-containing regimens. In those with HR-negative, HER2-positive disease, at least 2 prior anti-HER2 agents were required. Patients with TNBC needed to have exhausted all standard prior therapies, including prior treatment with a taxane and carboplatin.

An ECOG performance status of 0 to 2 and a life expectancy of at least 4 months were necessary for all patients.

All patients received cyclophosphamide given 2 to 3 days prior to Bria-IMT, which was given on day 0. Patients also received interferon at the inoculation sites 2 days (± 1 day) after Bria-IMT. Along with the Bria-IMT regimen, patients were randomly assigned to receive retifanlimab once every 3 weeks starting in cycle 1, or sequential treatment with the first dose of retifanlimab given in cycle 2.

Safety served as the trial’s primary end point. Secondary end points included overall response rate and duration of response.

“BriaCell’s phase 2 data indicate a robust survival signal and a well-tolerated profile,” Adam M. Brufsky, MD, PhD, FACP, a professor of medicine at the University of Pittsburgh School of Medicine and medical director of the Magee-Women’s Cancer Program in Pennsylvania, added in the news release.¹ “These results reinforce BriaCell’s potential to improve survival and tolerability for late-stage patients.”

References

1. BriaCell phase 2 survival achievement: 52% of patients surpass one-year milestone in metastatic breast cancer. News release. BriaCell Therapeutics. https://finance.yahoo.com/news/briacell-phase-2-survival-achievement-113000536.html
2. BriaCell phase 2 survival data beats leading standard in HR+ breast cancer. News release. BriaCell Therapeutics. April 16, 2025. Accessed July 8, 2025. https://briacell.com/briacell-phase-2-survival-data-beats-leading-standard-in-hr-breast-cancer/
3. Combination study of SV-BR-1-GM with retifanlimab. CliniclaTrials.gov. Updated February 4, 2025. Accessed July 8, 2025. https://clinicaltrials.gov/study/NCT03328026