Jointly discovered KAT6i molecule originating from Australian research has initiated Phase 3 in HR+ HER2- Breast Cancer with Pfizer Inc

Australian scientists who discovered how to "turn off" genes that make cancer cells grow are celebrating the next phase of development – with Pfizer's first in class KAT6 inhibitor PF-07248144 now moving to the next stages of clinical investigation.

MELBOURNE, Australia, Sept. 15, 2025 /PRNewswire/ -- Australian biotechnology investment and commercialisation incubator, Oncology One Pty Ltd, is pleased to report that PF-07248144, Pfizer Inc's clinical drug candidate discovered from Oncology One's out-licensed KAT6 inhibitor program, has now commenced a Phase 3 clinical trial, a key milestone.

Quick facts: PF-07248144 is a selective catalytic inhibitor of KAT6 (KAT6A/B), members of the histone lysine acetyltransferase family of enzymes that are involved in regulating gene expression. In certain cancers, KAT6A/B gene activity is dysregulated promoting cancer cell growth. PF-07248144 suppresses this abnormal gene activity and thereby supresses cancer growth. Previous clinical trials have shown promise for treating advanced or metastatic hormone receptor positive, HER2-negative breast cancer.

Pfizer's KATSIS-1 trial, a Phase 3 clinical trial of PF-07248144 combined with fulvestrant, is now published on clinicaltrials.gov. Reference ID NCT 07062965, "A study to Learn About the Study Medicine called PF-07248144 in Combination with Fulvestrant in People with HR-Positive, HER2 Negative Advanced or Metastatic Breast Cancer Who Progressed After a Prior Line of Treatment". The KATSIS-1 trial will have a broad international footprint, seeking to enrol up to 400 subjects across many trial sites including Australian hospitals and specialty breast cancer units.

Although early detection has dramatically improved the overall survival rate of breast cancer, it is estimated that 10,000 – 12,000 Australians are currently living with metastatic disease. The most common cancer type, HR+ HER2- metastatic breast cancer, is responsible for approximately 2, 500 deaths each year, or six Australians per day, indicting a clear need for better treatment of this disease.  This investigational drug provides new hope for people whose cancer has failed to respond to all previous lines of treatment.

The progress of PF-07248144 represents a major win for Oncology One and validation for the multiple research institutes, biotechnology companies and researchers who participated in the Cancer Therapeutics CRC (now Canthera Discovery) to translate this original Australian research into a promising investigational drug.

In 2009, the KAT6 project was licensed into the Cancer Therapeutics Cooperative Research Centre (CTx), Australia's first cooperative drug discovery network funded by the Australian Federal Government and participating organisations. It was further developed by CTx and later licensed to Pfizer in 2018 by Oncology One (formerly CTxONE).

Oncology One Chair of Scientific Advisory Board, Professor Ian Street, said: "In the early 2000s at Walter and Eliza Hall Institute (WEHI), Anne Voss and Tim Thomas made foundational discoveries about KAT6A, a protein that is important for controlling gene expression during development and growth of some blood cancers.  Many CTx research and industry partners - Monash Institute of Pharmaceutical Sciences, SYNthesis Med Chem, Peter MacCallum Cancer Centre, WEHI, CSIRO, Griffith University, St Vincent's Institute of Medical Research, and the Children's Cancer Institute, along with Pfizer, have worked together to develop a new drug that targets KAT6. This is a deeply inspiring story of collaboration in Australia's medical research sector."

If successful, PF-07248144 is on track to become a therapeutic in a completely new class of drugs, which essentially turns off cancer cells and stops them from multiplying.

Professor Ian Street, said: "I would like to congratulate the visionary and talented Australian scientists and clinicians who contributed to the discovery and development of PF-07248144  – and of course, share our sincere gratitude to Pfizer for backing this potential cancer therapeutic so quickly into a Phase 3 Clinical Trial."

To learn more about investment or partnership opportunities with Oncology One, visit oncologyone.com.au.

About Oncology One

Oncology One Pty Ltd is a cancer research and drug development company. We work with partners to identify suitable programs and build value in high potential drug discovery projects. Oncology One has one out-licensed program and is a private company headquartered in Melbourne, Australia. For more information visit oncologyone.com.au.