Pharmaxis reports positive results from trial of PXS‐6302

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Pharmaxis (ASX:PXS) has announced that a phase 1c trial of its novel topical drug treatment for scarring has met its primary safety objective and two secondary biomarker endpoints in patients with established scars.

The study, led by surgeon Professor Fiona Wood AM and researchers at The University of Western Australia (UWA), assessed the safety and tolerability of PXS‐6302 when applied to areas of established scars on adult patients.

Skin biopsies were taken to quantify the enzyme inhibition and scar composition. A visual and physical assessment of the scars was added as an exploratory endpoint because it could not be predicted from the pre‐clinical evidence how long treatment would be needed to effect a change in an established scar.

PXS‐6302, formulated in a cream, is a first-in-class inhibitor of the lysyl oxidase enzymes (LOX) involved in the formation and maintenance of scars. It is a potential breakthrough treatment for patients with problematic scars.

The trial involved 42 people with any type of scar older than one year and at least 10 square centimetres in size. PXS‐6302 or placebo cream was applied three times a week for three months.

The primary endpoint of safety and tolerability was met. PXS‐6302 was very well tolerated and demonstrated a good safety profile. No serious adverse events were reported, and only two patients withdrew from the study after reporting redness and itching at the application site, which resolved after treatment was stopped.

The use of PXS‐6302 resulted in a mean 66 per cent reduction in LOX activity when measured two days after the last dose compared to baseline and to placebo group.

Professor Wood said, “This exploratory clinical study has significantly enhanced our understanding of the role of LOX enzymes in scarring and the scar process itself. PXS‐6302 safely inhibits these key enzymes to a significant degree and leads directly to an unprecedented change to the scar composition that we have not seen with any other form of treatment.

"We estimate that up to 50 per cent of the excess collagen in these patients’ scars has been removed and while the length of this Phase 1c safety study was not sufficient to change the appearance of an established scar the remodelling process will be ongoing and I’m confident we would see an improvement in scar appearance and physical characteristics if we observed them for longer.

“The collected data also bodes well for studying the effect of LOX inhibition on the prevention of scars after surgery and in younger scars where the remodelling process is more aggressive and probably more sensitive to intervention with a LOX inhibitor. This work is a particular passion of mine and I am looking forward to extending our collaboration with Pharmaxis for future studies.”

LOX plays a critical role in scar formation by crosslinking the collagen fibres. The resulting changes in collagen structure and increased rigidity of the tissue stimulates greater production of collagen and LOX which in turn leads to more scar tissue.

Pharmaxis CEO Gary Phillips added, “The pre‐clinical work conducted by Professor Wood’s team at UWA and published recently in Nature Communications clearly pointed to the significant role played by LOX enzymes in skin scarring. This first in man clinical study has underlined those findings and pointed the way for future clinical research for our pan‐LOX inhibitors. I am pleased to announce an extension of our collaboration with Professor Wood and her team at UWA and look forward to updating further details in the near future.”