May 10, 2022

Calgary, Alberta, CANADA CALGARY, Alberta, May 10, 2022 (GLOBE NEWSWIRE) -- Zenith Epigenetics Ltd. (“Zenith” or the “Company”) announced today the initiation of a Phase 2b Triple Negative Breast Cancer (TNBC) clinical trial combining ZEN-3694 + Pfizer Inc.’s Talzenna (talazoparib). The trial will continue to evaluate the efficacy and safety of this combination in patients with locally advanced or metastatic germline wild type BRCA1/2 TNBC. This Phase 2b trial is an extension of the recently completed Phase 1b/2 trial which met its primary efficacy endpoint of clinical benefit rate comprised of objective responses plus stable disease and which showed that the combination regimen was well tolerated. The Phase 2b extension will enroll patients who have previously been treated with a TROP2 antibody drug conjugate for locally advanced or metastatic disease. “The data from the Phase 1b/2 trial has shown that the ZEN-3694 plus talazoparib combination regimen induced durable responses in tumors of TNBC patients which do not harbor mutations in BRCA1/2," said Dr. Mark Robson, a principal investigator and medical oncologist at The Memorial Sloan Kettering Cancer Center. “These clinical results confirm the rationale and data from pre-clinical experiments which have shown that BET inhibition can sensitize wild type BRCA1/2 TNBC tumors to PARP inhibition. This interesting data warrants the continued clinical evaluation of this combination”. In the United States, talazoparib is currently approved under the brand name TALZENNA, which is a poly (ADP-ribose) polymerase (PARP) inhibitor indicated for the treatment of adult patients with deleterious or suspected deleterious germline BRCA-mutated (gBRCAm) HER2-negative locally advanced or metastatic breast cancer. Single agent PARPi are approved for gBRCAm HER2-negative locally advanced or metastatic breast cancer, as both PARP inhibition and non-functioning DNA repair proteins BRCA1/2 are required to block DNA repair and kill tumor cells (synthetic lethality). Preclinical and clinical data has shown that BET inhibition may reduce the levels of DNA repair proteins such as BRCA1/2 and RAD51 and thus create synthetic lethality in wildtype BRCA1/2 TNBC tumors when combined with PARP inhibition. “We are very pleased to advance our TNBC program to Phase 2b and closer to possible registration,” said Donald J. McCaffery, President and CEO of Zenith. “There is a significant unmet need in this aggressive cancer with few non cytotoxic therapy options available for the patient”. The data from the completed Phase 1b/2 part of the clinical trial will be presented in an oral poster discussion section at the annual ASCO conference in Chicago, Illinois on Monday, June 6, 2022. The abstract for this presentation will be released by ASCO on May 26, 2022, at 5:00 PM EDT on ASCO.org/Abstracts. Abstract Number: 1023 Abstract Title: A phase 1b/2 study of the BET inhibitor ZEN-3694 in combination with talazoparib for treatment of patients with TNBC without gBRCA1/2 mutations. Session Type/Title: Session Date and Time:  About Zenith and ZEN-3694 Zenith Epigenetics Ltd., a wholly-owned subsidiary of Zenith Capital Corp., is a clinical stage biotechnology company focused on the discovery and development of novel therapeutics for the treatment of cancer and other disorders with significant unmet medical need. Zenith Epigenetics is developing various novel combinations of BET inhibitors with other targeted agents. The lead compound, ZEN-3694, is in clinical development for various oncologic indications, specifically: Phase 2b metastatic castration resistant prostate (mCRPC) cancer trial in combination with androgen receptor inhibitor, XTANDI (enzalutamide), conducted in collaboration with Astellas Pharma and Newsoara Biopharma.Zenith and Newsoara are the trial sponsors. Phase 2b Triple Negative Breast Cancer (TNBC) trial in combination with the PARP inhibitor TALZENNA (talazoparib), conducted in collaboration with Pfizer and Newsoara Biopharma. Zenith and Newsoara are the trial sponsors. Phase 1b/2 androgen receptor independent mCRPC trial in combination with immune checkpoint inhibitor KEYTRUDA (pembrolizumab) and XTANDI, conducted in collaboration with Merck, the University of California, San Francisco, and the University of Michigan. Phase 1b/2 ovarian cancer trial in combination with immune-checkpoint inhibitors, nivolumab and ipilimumab, conducted by the National Cancer Institute in collaboration with Zenith and BMS. About Triple Negative Breast Cancer (“TNBC”) TNBC is an aggressive form of breast cancer with low survival rates. TNBC accounts for about 10-15% of all breast cancers and it differs from other types of invasive breast cancer in that it tends to grow and spread faster, has fewer treatment options, and tends to have a worse prognosis. The term triple-negative breast cancer refers to the fact that the cancer cells have only low or no amount of the receptors ER, PR, and HER2. Approximately 75,000 women in the US, Japan and the major EU countries are diagnosed with TNBC each year. For further information, please contact: Investor Relations & Communications