New treatment hope for PV


Dr Cavan Bennett (R) is pictured in the lab with Nathalie Cook OAM  (a PV patient) from the MPN AA who is part of the WEHI patient consumer program

A ground-breaking new treatment for polycythaemia vera (PV) has been developed here in Melbourne by researchers Dr Cavan Bennett and Professor Sant-Rayn Pasricha from the Walter and Eliza Hall Institute (WEHI). This treatment appears to avoid the need for venesections. Phase 1 clinical trials begin shortly. There will be 7 trial sites in Australia and more detailed information will be provided shortly.

A report on ABC Radio’s Health Report of 3 April this year outlines the potential benefits of this treatment for patients. The report is available to listen to HERE.

More detailed information about the research is available below.

” SLN124: ironing out a new treatment for Polycythaemia Vera (PV)

The average adult has approximately 3-4 grams of iron stored in their body. Large changes in the amount of stored iron can have drastic consequences, with too little iron (iron deficiency) causing chronic fatigue and brain fog. Two-thirds of the iron in the body is contained within red blood cells. As such, venesection (blood withdrawal – the first-line treatment of Polycythaemia Vera) induces iron deficiency by removing iron-containing red blood cells from the body. Consequently, chronic fatigue and brain fog are not uncommon in venesected patients.

A small amount of iron travels around the body in the liquid compartment of the blood (the plasma). Plasma iron supplies the body’s cells with their iron needs, most notably for producing new red blood cells. Iron in the plasma comes from two main sources: dietary iron and recycling iron contained within dying red blood cells in the spleen. The amount of iron entering the plasma is controlled by the levels of a hormone called hepcidin. Hepcidin prevents iron exiting the cells of the intestine and spleen and entering the plasma. Therefore, increases in hepcidin result in less plasma iron and, as such, less iron is available for producing new red blood cells. Hepcidin is produced in the liver and the biological pathway that leads to hepcidin production has an internal brake, which limits hepcidin production.

Researchers Dr Cavan Bennett and Professor Sant-Rayn Pasricha from the WEHI (Melbourne, Australia) therapeutically silenced hepcidin’s internal brake, TMPRSS6, in a new clinically relevant mouse model of Polycythaemia Vera. In doing so, they discovered that hepcidin levels increased and plasma iron levels went down. Furthermore, they showed that the increase in hepcidin acted as a sort of medical venesection and reduced the haematocrit of the Polycythaemia Vera mice by nearly 20%. However, they have revealed that unlike traditional venesection, therapeutically increasing hepcidin levels did not physically remove iron from the body and therefore did not lower the total body iron levels. Because of this, it is thought that compounds that silence hepcidin’s TMPRSS6 could replace traditional venesection. This would offer an alternative to venesection and importantly offer hope to the population of Polycythaemia Vera patients intolerant to venesection who currently have no alternative therapeutic options.

Dr Bennett and Professor Pasricha used a short interfering (si) RNA developed by Silence Therapeutics Plc to silence hepcidin’s TMPRSS6. SLN124 is a siRNA in development by Silence Therapeutics as a treatment for haematological conditions. SLN124 has a potential to modulate hepcidin by ‘silencing’ TMPRSS6 to increase hepcidin levels to restrict iron in the bone marrow thereby reducing red blood cell production. SLN124 is expected to replace venesection and reduce thrombotic risk while reallocating iron away from the bone marrow to improve PV symptoms including fatigue. SLN124 has demonstrated safety in healthy volunteers and is currently being assessed in patients with thalassaemia. A new study for SLN124 is starting in Australia (and other locations) to investigate the safety and efficacy of SLN124 in patients with Polycythaemia Vera. This is a two-part study:  the first part will look at different doses and the second part will compare a single dose with placebo. All patients participating in the phase 1 are eligible to participate in the phase 2. ”

The photo above was provided with kind permission of WEHI, and is Copyright:© WEHI (Walter and Eliza Hall Institute of Medical Research) 1G Royal Parade Parkville 3052


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