BCTXW BriaCell Therapeutics Corporation

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, announces positive clinical data of its lead product candidate, Bria-IMT™, to be presented in one oral presentation session (by Principal Investigator and Professor of Oncology, Mayo Clinic, Saranya Chumsri, MD), two poster sessions, and one abstract on the updated clinical data of BriaCell’s randomized Phase 2 study evaluating Bria-IMT™ in patients with advanced metastatic breast cancers at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting taking place taking place May 31 - June 4, 2024 at McCormick Place, Chicago, IL. The abstracts for these presentations are now available at https://conferences.asco.org/am/abstracts.

“Patients with heavily pretreated metastatic breast cancer that have developed resistance to antibody drug conjugates (ADC) face a very poor prognosis. Novel, well tolerated and effective treatments remain a critical need,” stated Sara A. Hurvitz, MD, Professor of Medicine, Fred Hutchinson Cancer Center and University of Washington and BriaCell medical advisory board member. “Early data from the BriaCell study are quite promising and if confirmed in the larger clinical trial could be a game changer for patients.”

“Bria-IMT™ is a novel therapeutic which has the potential to address a major therapeutic challenge in the management of progressive metastatic breast cancer, and these early results with preliminary activity in a refractory patient setting are encouraging,” stated Adam M. Brufsky, MD, PhD, FACP, Professor of Medicine at the University of Pittsburgh School of Medicine and a member of BriaCell’s medical advisory board.

“With 4 published abstracts and an oral presentation, we expect this year’s ASCO Annual Meeting to be a very important event for BriaCell,” stated Giuseppe Del Priore, MD, MPH, BriaCell’s Chief Medical Officer. “We are thrilled to present promising updated data from our Phase 2 Bria-IMT™ regimen showing clinical efficacy across all patient groups, along with a preferred safety profile.”

Oral presentation by Mayo Clinic Professor and Phase 2 Principal Investigator, Saranya Chumsri, MD, on Monday June 3; 11:30 AM-1:00 PM CDT

Abstract Number for Publication: 1022Title: Outcomes of advanced/metastatic breast cancer (aMBC) treated with Bria-IMT™, an allogeneic whole cell immunotherapy.Session Type and Title: Rapid Oral Abstract – Breast Cancer – Metastatic

Phase 2 clinical data of the Bria-IMT™ regimen in 54 advanced metastatic breast cancer patients who failed multiple prior treatments including ADCs and immune check point inhibitors (CPIs) (median of 6 prior treatments) are presented.

Clinical Efficacy

• Median progression free survival (PFS)# of 4.1 months in heavily pretreated ADC resistant patients
• PFS of 3.9 months in patients treated with planned pivotal Phase 3 formulation is double the PFS of patients in similar studies who received physician’s treatment of choice (the comparator in the ongoing phase 3 study)
• Overall response rate (ORR)## of 9.5% and clinical benefit rate (CBR)### of 55% in evaluable patients compares favorably with the literature (Table 1)
• 5/6 (83%) of evaluable patients (one inevaluable) with intracranial lesions treated with Bria-IMT™ in all BriaCell studies had intracranial responses, including complete and partial responses

# PFS is defined as the length of time during which a patient’s cancer does not get worse## ORR defined as the percentage of patients who achieved either a complete response (complete disappearance of tumor) or partial response (tumor volume reduction of 30% or more) ### CBR defined as percentage of patients whose disease shrinks or remains stable over a certain time period

Table 1: Bria-IMT™ and historical clinical data in aMBC patients who failed multiple prior treatments
Study	PFS (months)	ORR (%)	CBR (%)
BriaCell’s Phase 2 patients who received pivotal Phase 3 study formulation (Bria-IMT™ regimen)	3.9	9.5*	55*
BriaCell’s ADC Resistant Phase 2 patients who received pivotal Phase 3 study formulation (Bria-IMT™ regimen)	4.1	12**	53**
Bardia, A. et. al. 1	1.7	4	8
Tripathy D. et. al. 2	1.9	3	10
O’Shaughnessy J. et. al. non-TNBC 3	2.3	4	7
O’Shaughnessy J. et. al. TNBC 3	1.6	5	10
*Data is for evaluable patients, n=42 with 12 not evaluable.
** Data is for evaluable patients, n = 17 with 6 not evaluable.
1,2,3 Data is shown for the intent to treat population for the control group treated with treatment of physician’s choice, which is the comparator in the BriaCell’s ongoing pivotal Phase 3 study.
2 This paper describes patients with brain metastases.

Safety profile Therapy was well-tolerated with no Bria-IMT™ related discontinuations. Absence of both interstitial lung disease (ILD), a common serious adverse event with ADCs, and Bria-IMT™-related treatment discontinuations underscore Bria-IMT™’s excellent tolerability and favorable safety profile.

In conclusion, improved progression-free survival and clinical benefit, along with an excellent safety profile, were observed in heavily pre-treated advanced breast cancer patients versus literature reported data in other similar studies. BriaCell will continue to monitor these clinical responses in its current pivotal Phase 3 study of Bria-IMT™ and CPI in advanced metastatic breast cancer.

Poster presentations on Sunday June 2 9:00 AM-12:00 PM CDT include Drs. Hurvitz (Fred Hutchinson Cancer Center), Brufsky (UPMC), and Cristofanilli (Weill Cornell) as authors and will be detailed in a subsequent press release.

Following the presentations, copies of the presentations will be posted on https://briacell.com/scientific-publications/.

References

1. Bardia A, et al. Final Results From the Randomized Phase III ASCENT Clinical Trial in Metastatic Triple-Negative Breast Cancer and Association of Outcomes by Human Epidermal Growth Factor Receptor 2 and Trophoblast Cell Surface Antigen 2 Expression. J Clin Oncol. 2024 May 20;42(15):1738-1744. doi: 10.1200/JCO.23.01409. Epub 2024 Feb 29. PMID: 38422473.
2. Tripathy D, et al. Treatment with etirinotecan pegol for patients with metastatic breast cancer and brain metastases: final results from the phase 3 ATTAIN randomized clinical trial. JAMA Oncol. 2022;8(7):1047-1052. doi:10.1001/jamaoncol.2022.0514.
3. O’Shaughnessy J et al. Analysis of patients without and with an initial triple-negative breast cancer diagnosis in the phase 3 randomized ASCENT study of sacituzumab govitecan in metastatic triple-negative breast cancer. Breast Cancer Res Treat. 2022 Sep;195(2):127-139. doi: 10.1007/s10549-022-06602-7. Epub 2022 May 11. PMID: 35545724; PMCID: PMC9374646.

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 Dr. Saranya Chumsri’s delivery of an oral presentation outlining BriaCell’s positive clinical data of its lead product candidate, Bria-IMT™; BriaCell presenting two poster sessions and one abstract on the updated clinical data of BriaCell’s randomized Phase 2 study evaluating Bria-IMT™ in patients with advanced metastatic breast cancers at the 2024 ASCO; BriaCell’s collaboration with authors and BriaCell medical advisory board members Sara A. Hurvitz, MD, Professor of Medicine, Fred Hutchinson Cancer Center and University of Washington, Adam M. Brufsky, MD, PhD, FACP, Professor of Medicine at the University of Pittsburgh School of Medicine, and Massimo Cristofanilli, MD, Professor of Medicine, Weill Cornell Medical College, Cornell University; BriaCell’s Bria-IMT™ having the potential to address a major therapeutic challenge in the management of progressive metastatic breast cancer; and BriaCell continuing to monitor clinical responses in its pivotal Phase 3 study of Bria-IMT™ and CPI in advanced metastatic breast cancer, 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 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 & CEO1-888-485-6340info@briacell.com

Media Relations:Jules AbrahamCORE IRjulesa@coreir.com

Investor Relations Contact:CORE IRinvestors@briacell.com