BriaCell Presents Unprecedented Overall Survival Data in Metastatic Breast Cancer in Spotlight Poster at 2024 SABCS®

BriaCell Therapeutics Corp. (Nasdaq: BCTX, BCTXW) (TSX: BCT) (“BriaCell” or the “Company”), a clinical-stage biotechnology company that develops novel immunotherapies to transform cancer care, is pleased to showcase 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),” stated 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,” noted 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 vaccineTime: Wednesday, December 11, 2024 7:00 AM – 8:30 AM CSTPresentation 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-1431Title: Identification of antigenic determinants in SV-BR-1 derived cellular breast cancer vaccinesTime: Wednesday, December 11, 2024 5:30 – 7:00 PM CSTPresentation 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-2217Title: PD-L1 upregulation in circulating tumor associated cells predicts for clinical outcomes in a phase I/II clinical trial using SV-BR-1-GM vaccine with the checkpoint inhibitor retifanlimab in metastatic breast cancer patients, an interim analysisTime: Wednesday, December 11, 2024 12:00 – 2:00 PM CSTPresentation 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-1068Abstract Title: ASTRO-VAC CNS: Bria-IMT™ in the management of tumor agnostic metastatic CNS lesionsTime: Wednesday, December 11, 2024 5:30 – 7:00 PM CSTPresentation 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/.

About BriaCell Therapeutics Corp.

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

Safe Harbor

This press release contains “forward-looking statements” that are subject to substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this press release are forward-looking statements. Forward-looking statements contained in this press release may be identified by the use of words such as “anticipate,” “believe,” “contemplate,” “could,” “estimate,” “expect,” “intend,” “seek,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “target,” “aim,” “should,” “will,” “would,” or the negative of these words or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements, including those about the potential safety and efficacy of Bria-IMT™, along with its potential use in CNS metastases; biomarkers assisting with early identification of patients who would benefit from treatment with the Bria-IMT™ combination regimen; BriaCell expecting to replicate Phase 2’s survival and clinical benefit data in its ongoing pivotal Phase 3 study and the Company’s plans to share the data in the coming months; the Bria-IMT™ combination regimen’s ability to produce meaningful clinical and survival benefits in other cancer patients with CNS metastasis; the Company’s ongoing evaluation of biomarkers to predict clinical outcomes in its ongoing pivotal Phase 3 study in MBC; cell-based cancer vaccines potentially reducing cancer cells’ immune escape and leading to strong and long-lasting clinical outcomes in cancer patients; and CTCs, CAMLs and PD-L1 levels having the potential to be relevant indicators of clinical outcomes in MBC patients treated with Bria-IMT™ plus CPI are based on BriaCell’s current expectations and are subject to inherent uncertainties, risks, and assumptions that are difficult to predict. Further, certain forward-looking statements, such as those are based on assumptions as to future events that may not prove to be accurate. These and other risks and uncertainties are described more fully under the heading “Risks and Uncertainties” in the Company’s most recent Management’s Discussion and Analysis, under the heading “Risk Factors” in the Company’s most recent Annual Information Form, and under “Risks and Uncertainties” in the Company’s other filings with the Canadian securities regulatory authorities and the U.S. Securities and Exchange Commission, all of which are available under the Company's profiles on SEDAR+ at www.sedarplus.ca and on EDGAR at www.sec.gov. Forward-looking statements contained in this announcement are made as of this date, and BriaCell Therapeutics Corp. undertakes no duty to update such information except as required under applicable law.

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Contact Information

Company Contact:William V. Williams, MDPresident & [e-mail]

Media Relations:Jules AbrahamCORE [e-mail]

Investor Relations Contact:CORE [e-mail]