For patients given less than five years to live after being diagnosed with myelofibrosis, there is a new flicker of hope after clinical stage drug development company Pharmaxis (ASX: PXS) reported encouraging interim data from their Phase 2 trials.

Myelofibrosis is a rare cancer of the bone marrow affecting 15 per 1 million people worldwide. It is driven by fibrosis, or scar tissue build up within the bone marrow, which in turn disrupts production of normal blood cells. This results in reduced immunity, bleeding issues, anaemia and ultimately, poor patient outcomes.

The disease has a particularly poor prognosis. Some patients go on to develop acute myeloid leukaemia and many are not responsive or fail to tolerate current treatments that are limited in their effectiveness. Pharmaxis has just released interim clinical data from its phase 2 trial in these patients with no other treatment options taking its lead drug candidate PXS-5505. The results support the disease-modifying potential shown in earlier pre-clinical models.

With the trial, named MF-101, cleared by the FDA under the Investigational New Drug (IND) scheme, 6 patients have completed a 24-week treatment program. Of those patients, 5 have reported stable or improved bone marrow fibrosis scores as well as stable or improved platelet or haemoglobin scores whilst a further 2 of those patients have shown an improvement in their symptoms.

Dr Gabriela Hobbs MD, Assistant Professor, Medicine, Harvard Medical School & Clinical Director, Leukemia Service, Massachusetts General Hospital said, “PXS-5505 continues to be very well tolerated in the clinic with no severe treatment related adverse events reported.”

“Though still early in the dose expansion phase of the study, PXS-5505 appears to be stabilising and in some cases, improving the haemoglobin and platelet counts, which has also been associated with symptom improvements in those patients that were treated to 24 weeks.

“This is encouraging given the poor prognosis seen after ruxolitinib discontinuation with a median overall survival of only 11-14 months, typical of this study population. These results support further clinical investigation of PXS-5505 in myelofibrosis.”

Additional data supporting the potential of PXS-5505 may not be far away with 9 other patients undergoing treatment and expected to return clinical data in the weeks ahead. There are 18 recruitment sites actively recruiting in Australia, South Korea, Taiwan and the US with Pharmaxis predicting that the target recruitment of 24 patients will be reached by the end of the year and full trial results available in Q3 2023.

Gary Phillips, Pharmaxis CEO said, “We are confident that these results, if repeated in the whole study population, will satisfy regulatory requirements to continue the development of PXS-5505 in myelofibrosis and also excite clinicians, patients and industry groups who are closely following our progress with this novel mechanism.”

While thousands of myelofibrosis patients and their families eagerly await the full results from the MF-101 trial, medical researchers around the world also follow with interest. Preclinical data has shown PXS-5505 as a treatment in several other cancers including liver and pancreatic cancer by breaking down fibrotic tissue in tumours and enhancing the effect of chemotherapy treatment.

The myelofibrosis treatment market is conservatively estimated at USD $1 billion per annum with no current product on the market that can modify the disease.