Raajit Rampal, MD, PhD, Memorial Sloan Kettering Cancer Center, New York, New York, shares the results of a real-world clinical analysis evaluating hematologic responses among patients with myelofibrosis (MF), including patients with anemia, who were treated with pacritinib.

“Patients with myelofibrosis who were treated with pacritinib in a real-world setting, focusing on those with anemia, had an improvement in their hemoglobin an, in fact, stability in their hemoglobin. This was seen across the spectrum including patients with severe anemia and those with less severe anemia,” Dr Rampal explained.

“The utility of this data is that it tells us that what we saw in the clinical trial data is reflective of what is being seen by patients who are being treated, mostly in a community setting,” he added. 

Key Clinical Takeaways:

• Pacritinib, a JAK2/IRAK1 inhibitor with proposed ACVR1 pathway inhibition, was evaluated for anemia benefit among patients with myelofibrosis using real-world clinical data from community practices from 2022 to 2024.
• 148 patients treated with pacritinib who had > 90 days of follow-up were evaluated for hemoglobin response, defined as an increase ≥ 1.5 g/dL.
• Hemoglobin response: 
  • 65 of 148 patients achieved a hemoglobin response, with a median time to response of 40 days from index.
  • 49 of 148 patients achieved a response within the first 90 days.
• Hemoglobin benefit:
  • Additional responses occurred after 90 days, consistent with clinical observations that some patients require 4 to 6 months for improvement.
  • Hemoglobin improvements were observed across anemia severity, including patients with severe anemia, and most responders by day 90 had severe anemia.
  • Hemoglobin levels remained stable through 180 days among patients with severe and moderate anemia, supporting durability of the hematologic benefit.
• Platelet counts remained stable during follow-up.
• These real-world findings demonstrate similar findings to those of prior clinical trials, indicating that pacritinib can improve hemoglobin and maintain stability among patients with myelofibrosis treated in with pacritinib.

Transcript:

I am Raajit Rampal from Memorial Sloan Kettering Cancer Center. I'm here talking today about the abstract that we presented at ASCO this year entitled "Improved Hemoglobin Responses in Patients With Myelofibrosis Treated With Pacritinib in Real World Clinical Settings."

Data from several studies with pacritinib in patients with myelofibrosis has demonstrated that there can be an anemia benefit in which patients who were previously transfusion-dependent of pact red blood cells become in fact transfusion independent. We think [this] is due to inhibition of the ACVR1 pathway, which in part may be the reason for this. We know that the inhibition of this pathway seems to be the reason that other drugs such as momelotinib also have an anemia benefit. 

The goal of this study was to look in the real world setting and see do we see similar things with regards to transfusion changes or increases in hemoglobin in patients treated with pacritinib? Obviously patients treated in clinical trials are not always reflective of the patients we see in the real world.

This study used de-identified electronic data from community oncology practices for patients with myelofibrosis treated with pacritinib between 2022 and 2024, who had more than 90 days of follow-up. What the study was looking for was hemoglobin response, which was defined as a hemoglobin of greater than 1.5 grand per deciliter increase. Platelets were also monitored in these patients. 

In this study there were about 148 pacritinib-treated patients followed for more than 90 days. Importantly, about 65 of those patients achieved a hemoglobin response with a median of 40 days from index and 49 achieved a response within the first 90 days of index with the median of 33 days to response.

Now, that piece of information is important because what we have known is that the time to benefit with regards to hemoglobin can be variable. In some patients it can occur in the first several months, and some it takes more than a few months to occur, sometimes 4 to 6 months, for example. What this data is saying is that even for patients who weren't in that first group with immediate response, there was a response seen with longer follow-up. Interestingly, some of these patients did have severe anemia, and so there was in fact a benefit for patients across the spectrum of those who have anemia. 

In fact, the majority of patients who responded by day 90 had severe anemia. The hemoglobin remains stable through 180 days in patients with severe and moderate anemia. Importantly, with regards to other side effects of the drug potentially that being effects on the platelets, the platelet count was actually stable in these patients.

To conclude, and to put this into context, patients with myelofibrosis who were treated with pacritinib in a real-world setting, focusing on those with anemia, had an improvement in their hemoglobin an, in fact, stability in their hemoglobin. This was seen across the spectrum including patients with severe anemia and those with less severe anemia. The utility of this data is that it tells us that what we saw in the clinical trial data is reflective of what is being seen by patients who are being treated, mostly in a community setting.

Source:

Rampal R, Eiffert S, Marrone M, et al. Hematologic response in patients with myelofibrosis treated with pacritinib in real-word clinical settings. Presented at 2025 ASCO Annual Meeting. May 30-June 3, 2025; Chicago, IL. Abstract e23274.