Dr. William Williams reports

BRIACELL HIGHLIGHTS OUTSTANDING TOPLINE SURVIVAL AND CLINICAL BENEFIT DATA IN ADVANCED METASTATIC BREAST CANCER AT THE 2023 SABCS

Briacell Therapeutics Corp. has released continued outstanding top-line survival and clinical benefit data in advanced metastatic breast cancer patients treated with Bria-IMT in combination with an immune checkpoint inhibitor (CPI). The data are being revealed at the 2023 San Antonio Breast Cancer Symposium held at Henry B. Gonzalez Convention Center, San Antonio, Tex.

"The survival data in this heavily pretreated advanced metastatic breast cancer patients looks very promising and we are looking forward to validate these findings in the Prevail trial. Importantly, the favourable safety profile makes the novel treatment regimen an attractive choice for patients who are heavily pretreated and often cannot tolerate the harsh side effects of other therapies," stated Dr. Carmen Calfa, MD, clinical research lead for the breast site disease group at the University of Miami Miller School of Medicine, co-director of the Cancer Survivorship Program at Sylvester Comprehensive Cancer Center and principal clinical investigator of the phase 2 Bria-IMT study.

Abstract title: Randomized Phase 2 of Bria-IMT, an Allogenic Human Cell Line with Antigen Presenting Activity, in Heavily Pretreated Metastatic Breast Cancer

Submission ID: 1580375

Presentation ID: PO3-05-12

Spotlight session: Poster session 3

Session date and time: Thursday, Dec. 7, 2023, 12 p.m. to 2 p.m. CT

Phase 2 combination study of Bria-IMT with immune checkpoint inhibitor:

• The phase 2 study is fully enrolled.
• An aggregate of 54 advanced metastatic breast cancer patients have been enrolled in the study (11 patients with Keytruda (pembrolizumab), and 43 patients with Incyte's retifanlimab with one patient crossover from the Keytruda study to retifanlimab study).
• Data are available on 48 of these heavily pretreated metastatic breast cancer patients (average number of prior treatments is six).

Excellent overall survival and tolerability:

• Interim analysis using Kaplan-Meier curve method, measuring the probability of patients' survival in time, showed median overall survival (OS) of 13.4 months for 54 patients. This is a marked improvement over the benchmark 6.7 to 9.8 months reported in similar (third line or higher) patients.
• Thirty-two out of 42 patients that have received treatment since 2022 remain alive, suggesting tolerability and survival efficacy. The data will continue to mature as patients remain on the study.
• All patients were able to receive therapy with no toxicity-related discontinuations.

Immune response:

• In certain instances, Briacell's combination regimen turned cold breast cancer tumours hot and activated the patient's cancer-fighting immune system cells, including CD8+ tumour-infiltrating lymphocytes.
• Briacell's regimen reversed immune exhaustion in several heavily pretreated patients who had failed prior CPI treatments, suggesting potentially better clinical and survival outcomes in these patients.
• Bria-IMT before CPI showed a prolonged reduction in neutrophil to lymphocyte ratio (NLR), a significant predictor of clinical benefit in patients, and this optimized sequence is in use in the current pivotal phase 3 study (NCT06072612).

In summary, the consistent top-line survival and clinical benefits support Briacell's hypothesis of additive and/or synergistic effects of immune checkpoint inhibitors with Bria-IMT and support the continuing pivotal study of its combination regimen in the treatment of advanced metastatic breast cancer.

About Briacell Therapeutics Corp.

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

We seek Safe Harbor.