Can Bone Marrow Fibrosis Be Reversed?

While current myelofibrosis treatments like ruxolitinib (a JAK inhibitor) help manage symptoms such as an enlarged spleen or fatigue, they don’t address the underlying bone marrow scarring (fibrosis) that can worsen symptoms over time.

A new study was presented at the 66th annual American Society of Hematology, exploring the possibility of reversing bone marrow scarring. This could be achieved by combining ruxolitinib with a new treatment called PXS-5505. 

A New Treatment for Reversing Fibrosis?  

PXS-5505 is a new medication that targets lysyl oxidase enzymes. These enzymes cause collagen and elastin fibers in the bone marrow to become stiff and tangled, leading to fibrosis. By blocking these enzymes, PXS-5505 may help reduce or even reverse bone marrow scarring.

The Possibility of a New Combination for Myelofibrosis

A new phase 1/2a clinical trial looked at how safe and effective the combination of PXS-5505 and ruxolitinib is for patients with intermediate to high-risk myelofibrosis. The objective of this study was to assess safety and tolerability of this combination.

All participants had been taking ruxolitinib for a while (on average, over two years) but had not achieved remission before entering the study. Many had low hemoglobin levels, were transfusion-dependent, or had high-risk gene mutations.

PXS-5505 was given twice daily for up to 52 weeks alongside ruxolitinib. Patients could adjust their dose of ruxolitinib if needed, and if they had to stop it, they were still allowed to continue with PXS-5505.

The results reported in December 2024 showed that the combination was well-tolerated, with no major safety concerns. We are expecting updates and will report them as soon as they are available. 

Why This Matters for the Myelofibrosis Community

Understanding and treating the root cause of myelofibrosis can help develop new treatments that improve patient outcomes. While current therapies help with symptoms, they don’t stop the scarring process in the bone marrow. This ongoing damage can lead to worsening anemia, increased transfusion needs, and a reduced quality of life.

The potential of PXS-5505 lies in how it can modify the fibrosis progression. This could mean:

• Improved blood counts
• Reduced need for transfusions
• Longer-lasting disease control
• Better quality of life

This opens the possibility of having a treatment that goes beyond symptom relief and may actually change the disease’s course.

What’s Next?

This early-phase trial provides an important first step in understanding how PXS-5505 works with ruxolitinib. If the combination continues to benefit patients, it could be used in larger trials to confirm its benefits.

While more data is still to come, early results show that this approach is safe and can potentially address aspects of the disease that current treatments cannot.

Staying informed is key for advocating for new options that delay myelofibrosis progression. The more we understand about how the disease works (and how we can stop it), the closer we get to transforming care and giving people with myelofibrosis a better future.

Want to stay up to date on emerging myelofibrosis treatments? Explore our latest research articles and educational tools.

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Source: 

• Multicenter, Open-Label Phase 1/2a Study of Pxs-5505 and Ruxolitinib in Patients with Primary, Post-Polycythemia Vera (PV) or Post-Essential Thrombocythemia (ET) Myelofibrosis