Pharmaxis cleared to progress to phase 2 bone marrow cancer trial

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Pharmaxis (ASX:PXS) has announced further positive results of data analysis from a phase 1c clinical trial (MF-101) studying its drug PXS-5505 in patients with bone marrow cancer myelofibrosis for 28 days at three dosage levels. 

The company said the assessment with its proprietary assays of the highest dose has shown inhibition of the target enzymes, LOX and LOXL2, at greater than 90 per cent over a 24-hour period at day 7 and day 28.

It said the trial safety committee has reviewed the results and having identified no safety signals, has cleared the study to progress to the phase 2 dose-expansion phase where 24 patients will be treated at the highest dose twice a day for 6 months.

CEO Gary Phillips said, “We are very pleased to have completed the dose-escalation phase of this study with such clear and positive findings. We will now immediately progress to the phase 2 dose-expansion study where we aim to show PXS-5505 is safe to be taken longer-term with the disease-modifying effects that we have seen in the pre-clinical models. The trial infrastructure and funding is in place and we are on track to complete the study by the end of 2022.”

Commenting on the results of the trial Dr Gabriela Hobbs, an assistant professor of medicine at the Harvard Medical School and clinical director at Massachusetts General Hospital, said, “Despite improvements in the treatment of myelofibrosis, the only curative therapy remains an allogeneic stem cell transplantation, a therapy that many patients are not eligible for due to its morbidity and mortality. None of the drugs approved to date consistently or meaningfully alter the fibrosis that defines this disease. PXS-5505 has a novel mechanism of action by fully inhibiting all LOX enzymes.

"An attractive aspect of this drug is that so far in healthy controls and in this phase 1c study in myelofibrosis patients, the drug appears to be very well tolerated. This is meaningful as approved drugs and those that are undergoing study, are associated with abnormal low blood cell counts. Preliminary data thus far, demonstrate that PXS-5505 leads to a dramatic, >90% inhibition of LOX and LOXL2 at one week and 28 days. This confirms what’s been shown in healthy controls as well as mouse models, that this drug can inhibit the LOX enzymes in patients. Inhibiting these enzymes is a novel approach to the treatment of myelofibrosis by preventing the deposition of fibrosis and ultimately reversing the fibrosis that characterizes this disease.”

Pharmaxis said the phase 1c/2a trial aims to demonstrate that PXS-5505 is safe and effective as a monotherapy in myelofibrosis patients who are intolerant, unresponsive or ineligible for treatment with approved JAK inhibitor drugs. Trial sites will now open to recruit myelofibrosis patients into the 6-month phase 2 study in Australia, South Korea, Taiwan and the US.