BriaCell Presents Unprecedented Overall Survival Data in Metastatic Breast Cancer

BriaCell Therapeutics Corp. will showcased its impressive survival and clinical benefit data in MBC patients, including those with CNS metastases, treated with the Bria-IMT plus CPI regimen. The data is featured in BriaCell’s Spotlight poster presentation session, at the 2024 San Antonio Breast Cancer Symposium (SABCS) held at Henry B. Gonzalez Convention Center, San Antonio, TX.

“Metastatic breast cancer remains an essentially incurable disease, with a significant unmet medical need in patients who are relapsed/refractory to recently approved therapies such as CPIs and antibody-drug conjugates (ADCs),” said Dr. William V. Williams, BriaCell’s President & CEO. “We are very pleased with the Bria-IMT combination regimen’s tolerability profile, and most importantly its outstanding clinical activity in heavily pre-treated patients who failed other therapeutic options.”

“In addition to our striking survival data in MBC patients, we are excited by potential biomarkers for early identification of patients who would benefit from treatment with the Bria-IMT combination regimen,” added Giuseppe Del Priore, MD, MPH, BriaCell’s Chief Medical Officer. “We expect to replicate Phase 2’s impressive survival and clinical benefit data in our ongoing pivotal Phase 3 study.”

“While CNS metastatic disease has historically had a very poor prognosis, our clinical data to date, shows solid survival and clinical benefit in patients with CNS metastasis,” stated Sailaja Kamaraju, MD, Assistant Professor of Medicine at the Medical College of Wisconsin, Division of Hematology and Oncology. “We are optimistic that the Bria-IMT™ combination regimen, with its unique targeted mechanism of action, may be able to produce meaningful clinical and survival benefits in other cancer patients with CNS metastases who have lost hope with little to no other therapeutic options.”

The data presented is from the fully enrolled BriaCell Phase 2 combination study of Bria-IMT plus CPI.

An aggregate of 54 MBC patients were enrolled in the study – all treated with the Bria-IMT™ combination regimen {11 patients received KEYTRUDA (pembrolizumab), and 43 patients received Incyte’s retifanlimab with one patient cross over from the KEYTRUDA study to retifanlimab}. Data is available on all 54 of these heavily pre-treated metastatic breast cancer patients (average number of prior treatments = 6). Of these 54 patients, 37 were treated with the formulation currently under investigation in BriaCell’s ongoing pivotal Phase 3 study in metastatic breast cancer (listed on ClinicalTrials.gov as NCT06072612). Final median overall survival calculation for the patients in the Phase 2 portion of the study is pending, as most of these patients remain alive over 1 year following their start on the study. No Bria-IMT-related discontinuations have been reported to date.

The details about the Spotlight presentation and other poster sessions are as follows:

Abstract Number: SESS-1071 (Spotlight Poster)
Title: Overall survival results of Bria-IMT allogenic whole cell-based cancer vaccine
Time: Wednesday, December 11, 2024 7:00 AM – 8:30 AM CST
Presentation ID: PS3-06

Bria-IMT regimen’s impressive OS and tolerability in MBC patients

• Median overall survival (OS) to date of 13.4 months for Phase 2 patients treated with the Phase 3 formulation (15.6 months for those treated since 2022 with the Phase 3 formulation) double that of comparable patients in the literature (Cortes J, et al. Annals of Oncology 2018; Kazmi S, et al. Breast Cancer Res Treat. 2020; O’Shaughnessy J et al. Breast Cancer Res Treat. 2022; Tripathy D, et al. JAMA Oncol. 2022; Bardia A, et al. J Clin Oncol. 2024)
• Final Phase 2 OS calculation is pending as many patients remain alive well over 1 year after starting the study
• Median overall survival (OS) for patients who received the Phase 3 formulation in the Phase 2 portion of the study who also developed an immune response to the vaccine as measured by delayed-type hypersensitivity (DTH) not yet reached with >1 year follow-up
• 13.7 months median OS in MBC patients with central nervous system (CNS)/intracranial tumors treated with the Bria-IMT™ regimen with or without a CPI
• Objective response rates (ORR) and clinical benefit rates (CBR) were observed across all MBC patient subsets, but positive clinical outcomes were more prominent in HER2+ and HR+/HER2- patient subsets
• Bria-IMT™ regimen was well-tolerated and produced clinical benefit in heavily pretreated MBC patients
• Patients who developed a DTH response had lower neutrophil to lymphocyte ratio (NLR), suggesting improved clinical benefit in these patients
• Delayed-type hypersensitivity (DTH) response, and circulating tumor cells (CTC) levels were significantly different between patients who responded vs those who did not respond to the Bria-IMT combination regimen

In conclusion, clinical findings to date support the potential safety and efficacy of Bria-IMT, along with its potential use in CNS metastases, as well as the possible use of biomarkers to predict clinical outcomes in BriaCell’s ongoing pivotal Phase 3 study in MBC.

Abstract Number: SESS-1431
Title: Identification of antigenic determinants in SV-BR-1 derived cellular breast cancer vaccines
Time: Wednesday, December 11, 2024 5:30 – 7:00 PM CST
Presentation ID: P2-06-02

Summary:
BriaCell successfully identified immunogenic (i.e. immune system activating) peptides in patients treated with Bria-IMT, a cell-based cancer vaccine, and showed Bria-IMT™’s ability to produce a targeted immune response against tumor antigens.

• Key immunogenic peptides detected included those with post-translational modifications (PTMs), such as citrullination and cysteinylation, an important type of neoantigen that may be shared across many patients with cancer
• Highlighted the advantage of cell-based cancer vaccines over RNA and peptide-based vaccines including their ability to present a broad and diverse repertoire of antigens (i.e. both conventional and unconventional types)
• Cell-based cancer vaccines also display unknown, patient-specific neoantigens that are hard to reproduce with RNA or peptide vaccines
• Diverse antigen presentation produces a robust, polyclonal immune response, engaging both CD8+ and CD4+ T cells against multiple tumor target

In conclusion, scientific data presented suggests that the unique mechanism of cell-based cancer vaccines may reduce cancer cells’ immune escape and may potentially lead to strong and long-lasting clinical outcomes in cancer patients.

Abstract Number: SESS-2217
Title: PD-L1 upregulation in circulating tumor associated cells predicts for clinical outcomes in a Phase 1/2 clinical trial using SV-BR-1-GM vaccine with the checkpoint inhibitor retifanlimab in metastatic breast cancer patients, an interim analysis
Time: Wednesday, December 11, 2024 12:00 – 2:00 PM CST
Presentation ID: P1-01-17

Summary:
Interim analysis after at least one year of Bria-IMT plus CPI regimen shows the following:

• Significantly lowered levels of circulating tumor cells (CTCs) and cancer associated macrophage-like cells (CAMLs) in 40% of heavily pre-treated MBC patients
• Lower CTCs/CAMLs levels were significantly correlated with better survival outcomes (i.e. better PFS and trended for better OS)
• Bria-IMT appeared to increase PD-L1 levels in 15 patients which correlated with better clinical responses to combination treatment with the anti-PD-1 check point inhibitor retifanlimab

In conclusion, clinical data support the combination regimen in our ongoing pivotal Phase 3 study and suggests CTCs and CAMLs and PD-L1 levels may be relevant indicators of clinical outcome in MBC patients treated with Bria-IMT plus CPI.

Abstract Number: SESS-1068
Abstract Title: ASTRO-VAC CNS: Bria-IMT in the management of tumor agnostic metastatic CNS lesions
Time: Wednesday, December 11, 2024 5:30 – 7:00 PM CST
Presentation ID: P2-10-24

Results: The poster provides the details of a planned Phase 2 study design expanding the use of Bria-IMT™ + CPI to tumor agnostic cancer patients (i.e. kidney cancer, brain cancer, etc.) with central nervous system (CNS) metastasis.

To view the posters, please visit https://briacell.com/scientific-publications/.

BriaCell is a clinical-stage biotechnology company that develops novel immunotherapies to transform cancer care. More information is available at https://briacell.com/.