US orphan status for Pharmaxis cancer treatment

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Sydney-based biopharmaceutical company Pharmaxis (ASX:PXS) has announced the US FDA has granted orphan‐drug designation for its oral pan LOX inhibitor PXS‐5505 for the treatment of myelofibrosis.

Orphan designation qualifies the sponsor of the drug for various development incentives such as reduced regulatory fees and extended periods of market exclusivity. 

PXS‐5505 is an oral drug that inhibits all lysyl oxidase family members. The company said the compound successfully cleared pre‐clinical safety including six‐month toxicity studies and has shown significant reductions in fibrosis in in‐vivo models of myelofibrosis and other cancers.

"PXS‐5505 has shown to be well tolerated in Phase 1 single and multiple ascending dose studies in humans with an excellent pharmacokinetic and pharmacodynamic profile," said the company in a statement.

According to CEO Gary Phillips, “We are very pleased with the FDA orphan‐drug designation for PXS‐5505. Pharmaxis believes that the current treatments for myelofibrosis can be augmented by a pan‐LOX inhibitor and be disease-modifying in a market with high unmet need and significant deal values for programs with clinical proof of concept.

"We expect to file an investigational new drug (IND) application with the FDA shortly and will provide an update on the clinical trial plans at that time.”

Myelofibrosis is a rare cancer in which normal bone marrow tissue is gradually replaced with a fibrous scar‐like material.

Over time, this leads to progressive bone marrow failure preventing the production of adequate numbers of red cells, white cells and platelets. It has a poor prognosis and limited therapeutic options.

Apart from a small group of patients eligible for stem cell transplantation, the current standard of care is JAK1/2 inhibitors. They provide mainly symptomatic relief but carry a risk of worsening blood cell counts.

The company said a recent publication reported that Pharmaxis pan‐LOX inhibitor compounds significantly decreased the bone marrow fibrotic burden in two different models of primary myelofibrosis.