Dr. William Williams reports

BRIACELL PRESENTS ROBUST ANTI-CANCER ACTIVITY OF BRIA-OTS+™ AT SITC 2025

Briacell Therapeutics Corp. is presenting evidence of strong immune system engagement and anti-cancer activity of its next generation Bria-OTS+ platform in preclinical models at a poster presentation at the Society for Immunotherapy of Cancer (SITC) 40th Anniversary Annual Meeting, to be held Nov. 7 to Nov. 9, 2025, in National Harbor, Md.

• Next generation Bria-OTS+ platform demonstrates rapid, potent and durable anti-cancer activity by activating both innate and adaptive immune responses;
• Increased tumour cell cytotoxicity induced by both Bria-BRES+ (breast cancer) and Bria-PROS+ (prostate cancer);
• Preclinical data reinforces broad potential of Bria-OTS+ platform across multiple indications.

Title:  Redefining Cancer Vaccines: Bria-OTS+ Integrates Trained Innate Immunity and Adaptive Memory to Overcome Immune Resistance

Abstract No.:   353

Location:   Prince George ABC Exhibit Halls, Gaylord National Resort and Convention Center

Date:  Friday, Nov. 7, 2025

Time:   12:15 to 1:45 p.m., and 5:35 to 7 p.m. ET

"We are thrilled with the comprehensive, powerful and long-lasting immune activation demonstrated by Bria-OTS+ in our preclinical studies, which we believe will translate into meaningful anti-cancer immune responses in the clinic," stated Miguel A. Lopez-Lago, PhD, Briacell's chief scientific officer. "By training both the innate and adaptive arms of the immune system, Bria-OTS+ represents an important step toward developing more durable and broadly effective cancer immunotherapies."

"These findings add to the growing body of evidence supporting our Bria-OTS+ platform's unique mechanism of action for novel personalized cancer immunotherapies. We look forward to confirming these encouraging preclinical results in planned clinical trials of Bria-BRES+ for breast cancer and Bria-PROS+ for prostate cancer," commented Dr. William V. Williams, Briacell's president and chief executive officer.

Summary of preclinical findings

Bria-OTS+ fast acting and potent anti-cancer immune system activation

Bria-BRES+ and Bria-PROS+ rapidly activated key components of the immune system in preclinical models. The platform induced co-ordinated innate and adaptive immune responses, training the immune system to kill cancer cells. These findings are consistent with strong anti-tumour immune activity and support its promise as Briacell's next-generation cancer immunotherapy platform.

Bria-OTS+ long-lasting anti-cancer response

Both Bria-BRES+ and Bria-PROS+ produced sustained, and durable anti-cancer immune responses that may translate into prolonged clinical benefit for patients treated with the Bria-OTS+ platform of whole cell immunotherapies.

Bria-OTS+: broad applicability

Positive results with lead candidates Bria-BRES+ and Bria-PROS+ reinforce the broad applicability of the Bria-OTS+ platform and support possible expansion into other solid tumour indications. These data highlight the platform's capacity to generate broad and potent immune responses against multiple tumour types that share key immune-recognition features.

About Bria-OTS+

Bria-OTS+ is an advanced immunotherapy platform and an enhanced version of Bria-OTS, Briacell's personalized off the shelf breast cancer immunotherapy which has already demonstrated positive clinical results as announced on April 24 2025. Bria-OTS+ is designed to express multiple immune-activating cytokines and co-stimulatory molecules to further enhance immune engagement. Lead candidates Bria-BRES+ (breast cancer) and Bria-PROS+ (prostate cancer) have completed GMP manufacturing and are expected to be evaluated in upcoming phase 1/2a clinical studies with Bria-PROS+ supported by a $2-million National Cancer Institute (NCI) Small Business Innovative Research (SBIR) award announced on Aug. 25, 2025.

About Briacell Therapeutics Corp.

Briacell is a clinical-stage biotechnology company that develops novel immunotherapies to transform cancer care.

We seek Safe Harbor.