Pharmaxis reports positive analysis of data from phase 2 PXS-5505 study

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Pharmaxis (ASX:PXS) has announced details of a final interim analysis of data from ten patients who have completed six months treatment with PXS-5505.

The phase 2 open-label phase clinical involved patients with a bone marrow cancer known as myelofibrosis.

The trial known as MF-101 aims to demonstrate that PXS-5505, an inhibitor of all lysyl oxidase enzymes (LOX), is safe and effective as a monotherapy in myelofibrosis patients who are intolerant, unresponsive or ineligible for treatment with approved JAK inhibitor drugs.

These patients have very limited treatment options and a life expectancy of approximately one year.

A total of 21 patients have been enrolled in the cohort expansion phase of the study. Ten patients have completed 24 weeks of treatment.

Pharmaxis said PXS-5505 was well tolerated, with no serious treatment-related adverse events, and has promising signs of clinical efficacy. These signs include improved symptom scores, stable or improved hematological parameters and reduced bone marrow fibrosis. Ten patients have dropped out of the study due to a lack of clinical response or adverse events unrelated to the drug.

According to Dr Lucia Masarova, assistant professor at the Department of Leukemia at MD Anderson Cancer Center in Houston, “PXS-5505 continues to show not only an excellent safety profile but also promising clinical activity. The effect on bone marrow fibrosis is particularly exciting for a disease like myelofibrosis, where despite numerous years of research, we do not have any effective anti-fibrotic drugs.

"It is encouraging to see that majority of 10 patients who completed 24 weeks of therapy also had improvements of symptoms and more importantly, stable or improved blood counts; including in those patients with severe thrombocytopenia.

“These results support plans to continue clinical investigation of the agent, including combinations with JAK inhibitors where the lack of overlapping hematological toxicity would make PXS-5505 an ideal add-on candidate.”

Pharmaxis said the final results from this cohort will be submitted for presentation at the American Society of Haematology conference later this year.

“Pharmaxis is the only company with pan-LOX inhibitors in clinical development,” said CEO Mr Gary Phillips.

“The results from this trial with an oral LOX inhibitor showing significant improvements in fibrosis grade in bone marrow biopsies corroborate the findings of the trial of our topical LOX inhibitor in established skin scars where we saw a 30% reduction in collagen in skin biopsies after only 3 months treatment.  Further to the published pre-clinical research showing disease modification in several different indications, this is a mechanism which is now proven to be anti-fibrotic in patients.”

Mr Phillips added, “The excellent safety profile of PXS-5505 makes it an ideal candidate to combine with JAK inhibitors, the current standard of care in myelofibrosis. We anticipate that the impact on bone marrow fibrosis and other clinical parameters from the antifibrotic and intracellular effects of LOX inhibition should lead to improved outcomes for patients. We look forward to FDA feedback on our protocol and expect to start recruitment of this next cohort later this year.”