Bria-IMT Plus Checkpoint Inhibition Yields Potential OS Benefit in Pretreated HR+ Breast Cancer

Breast Cancer | Image Credit:
© Sebastian Kaulitzki – stock.adobe.com

Treatment with the off-the-shelf, targeted, cell-based immunotherapy Bria-IMT (SV-BR-1-GM) in combination with immune checkpoint inhibition led to overall survival (OS) outcomes that exceeded historical data for sacituzumab govitecan-hziy (Trodelvy) in heavily pretreated patients with metastatic hormone receptor (HR)–positive breast cancer, according to data from a phase 2 trial (NCT03328026).1,2

Findings showed that patients treated with Bria-IMT plus retifanlimab (Zynyz; n = 25) experienced a median OS of 17.3 months.1 Notably, this patient population received a median of 6 prior lines of therapy.

Data from the phase 3 TROPiCS-02 trial (NCT03901339), which supported the FDA approval of sacituzumab govitecan for patients with unresectable locally advanced or metastatic HR-positive, HER2-negative breast cancer who have received endocrine-based therapy and at least 2 additional systemic therapies in the metastatic setting, showed that patients treated with the antibody-drug conjugate achieved a median OS of 14.4 months.1,3

Findings from the phase 2 study also showed that patients with triple-negative breast cancer (TNBC) treated with Bria-IMT plus retifanlimab experienced a median OS of 11.4 months; this population also received a median of 6 prior lines of therapy.1

“We are truly impressed with the survival benefit data of the regimen that exceeds or meets those of sacituzumab govitecan in [patients with] HR-positive [breast cancer] and TNBC, respectively. Bria-IMT appears to be very well-tolerated,” William V. Williams, MD, president and chief executive officer of BriaCell Therapeutics, stated in a news release. “We look forward to further confirming this clinical data in our ongoing pivotal phase 3 [BRIA-ABC] study [NCT06072612] with OS as its primary end point.”

The phase 2 trial enrolled patients at least 18 years of age with histologically confirmed recurrent or metastatic breast cancer whose disease progressed on prior therapy.4 For enrolled patients with metastatic breast cancer, those with HR-positive, HER2-positive disease needed to must 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; those with HR-negative, HER2-positive disease were required to have received at least 2 anti-HER2 agents; and patients with TNBC needed to have exhausted all standard prior therapies, including prior treatment with a taxane and carboplatin.

Other key inclusion criteria comprised an ECOG performance status of 0 to 2 and a life expectancy of at least 4 months.

The administration of Bria-IMT included cyclophosphamide given 2 to 3 days prior to the immunotherapy. Inoculation with Bria-IMT occurred on day 0, and patients also received Interferon at the inoculation sites 2 days (±1 day) day after Bria-IMT. All patients received this regimen, and they 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.

“HR-positive [breast cancer] and TNBC represent a significant proportion of the patient population and are the most difficult patient groups to treat. They have limited therapeutic options and [an] OS of only a few months,” Giuseppe Del Priore, MD, MPH, chief medical officer of BriaCell Therapeutics, added in the news release.1 “Our clinical data support our hypothesis that the Bria-IMT regimen plus [checkpoint inhibition] has the potential to address the unmet medical needs of [patients with] HR-positive [breast cancer] and TNBC, and provide an effective and well-tolerated therapeutic option.”

References

1. BriaCell phase 2 survival data beats leading standard in HR+ breast cancer. News release. BriaCell Therapeutics. April 16, 2025. Accessed April 17, 2025. https://feeds.issuerdirect.com/news-release.html?newsid=6008109823653589&symbol=BCTX
2. Bria-IMT cell therapy. BriaCell Therapeutics. Accessed April 17, 2025. https://briacell.com/briaimt/
3. FDA approves sacituzumab govitecan-hziy for HR-positive breast cancer. FDA. February 3, 2023. Accessed April 17, 2025. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-sacituzumab-govitecan-hziy-hr-positive-breast-cancer
4. Combination study of SV-BR-1-GM with retifanlimab. CliniclaTrials.gov. Updated February 4, 2025. Accessed April 17, 2025. https://clinicaltrials.gov/study/NCT03328026