Patrys' deoxymab significantly increases survival in animal model

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Patrys (ASX:PAB) has announced data from its completed pre-clinical study that has demonstrated that its full-sized deoxymab antibody, PAT-DX3, can be used as a targeting agent for antibody-drug conjugates (ADC) to deliver anti-cancer drugs to tumours.

In September, the company announced preliminary data showing that the administration of an ADC in which PAT-DX3 was conjugated to the anticancer drug monomethyl auristatin E (MMAE) significantly inhibited the growth of tumours in mice implanted with xenografts of the human breast cancer cell line MCF7.

Patrys now reports that this inhibition of tumour growth resulted in a significant improvement in survival in animals treated with the ADC based on Patrys’ PAT-DX3 deoxymab.

At day 60, the completion date for this study, 80 per cent of the animals treated with PAT-DX3-MMAE were still alive. This was 39 days after the last treatment with PAT-DX3-MMAE was administered. By comparison, all of the animals in the untreated control group had been euthanised because of tumour growth by day 60 (black), and only one animal treated in the non-specific, control antibody group remained alive. PAT-DX3-MMAE significantly increased survival compared to the control group of animals, said the company.

CEO and managing director Dr James Campbell said, “It is very exciting to report such positive data from our proof-of-concept study showing that Patrys’ deoxymabs may have potential as targeting agents for ADCs.

“While most ADCs are based on antibodies directed against cell surface antigens that are specific for a particular tumour, our deoxymabs are attracted to the DNA that is released from most cancers as a result of the high rates of cell death and cell turnover in tumours.

“This preclinical study has shown that the affinity our deoxymabs have for DNA is sufficient for them to target the delivery of cancer drugs to tumours where they can inhibit tumour growth and improve survival. This exciting finding may open up new opportunities for deoxymabs as a basis for developing new therapeutic ADC products.

"Additional studies will need to be performed to better understand the potential impacts of on-target and off-target toxicity using this approach; however, the results from this study have clearly demonstrated the proof-of-concept. “We look forward to advancing this program as an adjunct to our planned first in human clinical study of PAT-DX1, which remains on track for late 2022.”