New pre-clinical data results released by therapeutic antibody developer Patrys Limited (ASX: PAB) have shown its new drug candidate PAT-DX1 has potential to increase survival rates in metastatic triple-negative breast cancer patients with secondary brain tumours.
Ongoing testing of the drug is being done on mouse models of TNBC brain metastases by Dr James Hansen and Dr Jiangbing Zhou at Yale University’s School of Medicine.
The most recent tests have shown that when PAT-DX1 has been administered by tail vein injection, the survival rate can be significantly enhanced.
Prior to commencement of the tests, brain metastases were artificially generated by injecting luciferase-labelled, brain-seeking TNBC cells directly into circulation, via intracardiac injection.
One week later, the presence of the metastases was confirmed and intravenous treatment with PAT-DX1 was initiated.
The ability of PAT-DX1 to reduce TNBC brain metastases was seen after just one week of treatment.
After one month of treatment, the treated mice showed 93% less metastases than untreated mice, quantified by luminescence intensity.
The drug also significantly enhanced survival rate, with 86% of mice treated with PAT-DX1 still alive after all control mice had died.
No toxicity associated with PAT-DX1 treatment was observed.
Patrys chief executive officer James Campbell said the new results add further promise to the drug’s ability to fight TNBC – considered to be the most therapeutically-challenging form of breast cancer.
“Drs Hansen and Zhou have previously shown us that PAT-DX1 crosses the blood-brain barrier to suppress glioblastoma tumours,” he said.
“This new demonstration against TNBC brain metastases has important implications for potential applications of the drug in the treatment of a wide range of brain tumours.”
Whole-of-brain radiotherapy is the current standard of care for breast cancer patients who develop brain metastases.
Mr Campbell said the study team will conduct a follow-up experiment in the same metastatic mouse model to determine whether PAT-DX1 in combination with radiotherapy might be even more effective than either treatment used alone.
In a range of pre-clinical cancer models, PAT-DX1 has shown significant ability to kill cancer cells in cell models, human tumour explants, xenograft and orthotopic models.
Treatment with PAT-DX1 has also been shown to significantly improve survival in an orthotopic model of glioblastoma, and work in synergy with approved ADP-ribose polymerase (PARP) inhibitor Olaparib.
Mr Campbell said PAT-DX1 may have positive applications across a range of malignancies such as gliomas, melanomas, prostate, breast, pancreatic and ovarian cancers.
Leading cause of death
Breast cancer is currently the leading cause of cancer death in women, with approximately 1.67 million new cases diagnosed worldwide each year.
Sub-types are stratified in accordance with their expression of oestrogen, progesterone and HER2 receptors and tumours which lack all three receptors are referred to as triple negative breast cancers.
TBNC accounts for around 20% of all breast cancer cases and is believed to be the most aggressive and difficult to treat.
It is associated with BRCA gene mutations which make cancer cells vulnerable to the inhibition of DNA damage repair, such as that offered by PAT-DX1.
At midday, shares in Patrys Limited were trading 19.23% higher at $0.031.