MPN Workshop of the Carolinas 2025 | Sequencing pacritinib relative to other JAK inhibitors in MF and transitioning from ruxolitinib

So I will typically use pacritinib on label, which is to say I use it in patients with less than 50,000 platelets. And while on that subject, I will quickly say that I will occasionally use it in people with higher than 50,000, but still close to 50,000, by which I mean, you know, if I use it in, you know, if I use a different JAK inhibitor in somebody with 60,000 platelets and they’re likely to drop and then I’m likely to have problems and therefore I’ll often use pacritinib in that situation as well, given that the pivotal trial allowed platelets up to 100,000. So I’m backed by data, even though the label is a bit more restrictive, but I will use it sometimes in those, you know, low, but a little higher than 50 platelets. 

Now, these patients tend not to be frontline patients. Frontline patients typically are not going to have very low platelets. I think that’s very rare. It’s been reported to be around 10%, but that’s not my experience. I feel like it’s a lot less. So I will usually use pacritinib, you know, second and third line, again, you know, sort of directed by the platelets if they’re less than 50 for sure and sometimes even if they’re slightly elevated. 

Now what is interesting is something I alluded to. It has an anemia benefit, but so does momelotinib and momelotinib is approved for myelofibrosis with anemia. So generally when the issue is anemia I favor momelotinib but there are situations where say the platelets are marginal and I’m, you know, inclining towards pacritinib, and I also know that it has an anemia benefit. So in those situations, it can be a nice, you know, alternative that can do both, you know, that can be safe on the platelets and help with the anemia. So I would say, you know, second and later lines for me, for the most part. 

And then a very quick point about transitioning, since you asked about sequencing. And you know transitioning from ruxolitinib to pacritinib I think people can do it differently, but one thing I will say is that while there could be a range of ways of doing it what’s important to remember is that with pacritinib, it has a longer half-life and it has no JAK1 activity. For this reason if you switch directly from ruxolitinib to pacritinib without a taper or an overlap, you could run into what’s called ruxolitinib discontinuation syndrome, which can be pretty miserable in some patients. So a rebound or a flare phenomenon. So what I like to do is I like to overlap a small dose of ruxolitinib, just 5 mg twice a day, with a week of pacritinib before stopping the rux altogether and continuing on with the pacritinib.

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