US FDA clears Pharmaxis' trial of PXS‐5505 in liver cancer

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The US FDA has cleared Pharmaxis' (ASX:PXS) Investigational New Drug (IND) application for a trial of PXS‐5505 in patients with hepatocellular carcinoma (HCC).

The IND was submitted by the University of Rochester Medical Center following the positive pre‐clinical results reported in August 2021 at the Americas Hepato‐Pancreato‐Biliary Association conference.

The trial design approved by the FDA calls for PXS‐5505 to be added to the current chemotherapy standard of care - the combination of a PD‐L1 inhibitor and an anti‐VEGF drug as first-line therapy in newly diagnosed patients with unresectable HCC carcinoma.

Primary liver malignancies have doubled in incidence over the last two decades. These malignancies are now the fourth leading cause of cancer‐related mortality worldwide with a 19.6 per cent five‐year relative survival rate.

Currently, just 20‐30 per cent of HCC are resectable at presentation with many patients relying on chemotherapy.

A prominent feature of HCC is the presence of highly fibrotic tissue that increases tumour stiffness and decreases access of drugs into the tumour.

Under the guidance of Dr Roberto Hernandez‐Alejandro, the research team at the University of Rochester Medical Center have been investigating the role of lysyl oxidase enzymes in liver cancer and whether Pharmaxis’ PXS‐5505 can
improve the efficacy of current chemotherapy drugs by inhibiting these enzymes.

Dr Hernandez‐Alejandro said, "At the University of Rochester Wilmot Cancer Center, we are excited about the prospect of combining PXS‐5505 with standard first-line therapy for our unresectable hepatocellular carcinoma patients. The incidence of hepatocellular carcinoma is rising in part due to increasing incidence of cirrhosis and non‐alcoholic steatohepatitis. Beyond resection, effective systemic therapies for this disease are lacking, thus new treatment regimens are of significant clinical need.”

Dr Nabeel Badri added, “PXS‐5505 is a potent inhibitor of lysyl oxidase, a key enzyme in collagen crosslinking. By inhibiting the formation of fibrotic tissue in the tumor we hope to improve delivery and effectiveness of immunotherapy drugs which
have so far had a limited impact of the survival of our patients. Through preclinical testing and translational research, we have developed a promising clinical trial design that has the potential to benefit these patients and improve our understanding of hepatocellular carcinoma."

The approved trial design envisages a dose-escalation stage where the safety of PXS‐5505 in combination with a PD‐L1 inhibitor and an anti‐VEGF drug will be assessed at several different doses as well as measures designed to explore the impact of PXS‐5505 on fibrosis and drug perfusion. This will be followed by a 6‐month trial of the selected dose with both safety and efficacy endpoints.

Pharmaxis CEO Gary Phillips said, “We highly value our collaboration with the research team at University of Rochester. The rapid progression from the compelling pre‐clinical work presented for the first time in August to a successful IND submission is very encouraging and we look forward to concluding arrangements for the commencement of the dose-escalation study in 2022. PXS‐5505 has recently progressed to a phase 2 clinical trial looking for evidence of disease-modifying effects in
the bone cancer myelofibrosis as a monotherapy so exploring its additional potential to address cancers where fibrosis is limiting the clinical benefit of current chemotherapy‐ such as liver and pancreatic cancer‐ would be significantly value adding.”