During a Targeted Oncology™ Case-Based Roundtable™ event, Naveen Pemmaraju, MD, and participants discussed the role of JAK inhibitors in managing myelofibrosis particularly in younger patients who may receive allogeneic stem cell transplant. This is the first of 2 articles based on this event.
A 62-year-old man presented to his primary care physician (PCP) with symptoms of fatigue, night sweats, and increased bruising. He had a history of type 2 diabetes, hypercholesteremia, and hypertension. The PCP noticed lower hemoglobin concentration (11 to 9.5 g/dL) and platelet count (350 × 109/L to 195 × 109/L) from a previous annual physical examination. He was referred to a hematologist/oncologist for consultation and evaluation.
Two months post-PCP visit, he went to a hematologic oncologist. Exam findings included a spleen 5 cm below left costal margin, fatigue and night sweats worsening, bone pain, hemoglobin of 8.7 g/dL, and platelet count of 135 × 109/L . He was diagnosed with primary myelofibrosis (MF); bone marrow fibrosis of grade 2, with 35% bone marrow blasts. He had a history of squamous cell carcinoma of the skin.
Molecular analysis showed a JAK2 V617F mutation and normal cytogenetics. Blood smear reveals leukoerythroblastosis: 1% blasts by manual count/flow cytometry. His ECOG performance status (PS) was 2.
DAI CHU LUU, MD: My standpoint is that a 62-year-old is still young. I have transplant physician within 5 miles of my practice. I would definitely send to a transplant physician…see what they have to say, and then follow up on the recommendations. Usually they’ll give recommendations and then I’ll act on them. Whenever things get tough, I’ll send it to them to establish care.
NAVEEN PEMMARAJU, MD: That’s great. What do you think about JAK [Janus kinase] inhibitor therapy? [Would you use] monotherapy as standard of care up until the transplant?
PEMMARAJU: If the platelets are below 50 × 109/L, what we’ve been doing [in the past] is either giving ruxolitinib [Jakafi] or low-dose ruxolitinib. Maybe you’re doing something different. Has anyone yet prescribed the new agent, pacritinib [Vonjo], which is approved in this lower than 50 × 109/L setting?
SRIKAR MALIREDDY, MD: I have prescribed pacritinib. I had a patient on ruxolitinib for the longest time and then eventually the disease progressed and I could not do any more administration of ruxolitinib. He’s been on [pacritinib] for at least 7 to 8 months.
PEMMARAJU: [Was there] any diarrhea or bleeding events? Or has it been well tolerated?
MALIREDDY: There were no [tolerability issues]. I was very careful with starting with a low dose, and then ramping up. We also watched the platelet counts, and so far...[he has] 30 × 109/L to 40 × 109/L platelets.
PEMMARAJU: What dose did you start? Did you start at 100 mg? Because the approved dose is 200 mg twice daily.1
MALIREDDY: Yes, I started at 100 mg. [Since] he was tolerating it, he is at the maximum dose right now. He’s at 200 mg.
PEMMARAJU: That’s a great story. Did you have any difficulty getting it through insurance or through your specialty pharmacy?
MALIREDDY: This was one of the patients…who initially got azacitidine [Onureg] in combination with ruxolitinib. He was on a clinical trial for that.
PEMMARAJU: For the ruxolitinib/azacitidine trial [NCT01787487]?
MALIREDDY: Yes, exactly. He had some severe cytopenias, myelosuppression, and all that [on the clinical trial]. Eventually, the cytopenias progressed, then [he started on pacritinib]. I didn’t have any issues with getting approval.
PEMMARAJU: That’s great. The combined answer from both of you is the cutting-edge state of the art, which is offering a JAK inhibitor [while] trying to get to [allogeneic stem cell] transplant. We all assume—and it ends up being correct a lot of the time in our patients with myeloproliferative neoplasms as opposed to leukemia or some of the other [disease] states— what happens is [patients have an] ECOG PS of 2 to 3, but they have PS of 0 to 1 after the initiation of JAK inhibitor. With ruxolitinib, it’s usually about 3 months that you see it. After 1 week to 1 month, you start feeling great; by month 2 and 3 is the plateau.
PEMMARAJU: All of us in the field are thinking about the significance of cytopenic MF. It helped lead to the drug approval for this JAK inhibitor [pacritinib], which is great because I have had several similar situations in prescribing it. It’s a very well tolerated drug. But…how frequent is this? Most people in our field think that the cytopenias are treatment related or they happened later on. That is common. But thrombocytopenia and anemia can occur in a quarter or more of our patients at baseline. Some of these patients present…with fairly advanced disease. How often do you encounter a baseline platelet count of less than 50 × 109/L at any point in the myelofibrosis trajectory? And before pacritinib…what were you giving these patients if you had to treat them?
JAGATHI CHALLAGALLA, MD: [I would give] low-dose ruxolitinib, or if they’re transfusion independent, just observation.
PEMMARAJU: Yes, exactly, [or] sometimes we would…give danazol or steroids. Now we know that delivering suboptimal doses is leading to suboptimal outcomes.2 If you’re not reducing the spleen, not improving the symptoms, patients won’t do as well. The benefit of pacritinib…is you can give the full dose of the drug. We heard 1 story of being very cautious, but you can prescribe it as the 200 mg dosing even in the thrombocytopenic setting.1 Just watch out for diarrhea, usually resolved in the first 4 to 6 weeks. It’s usually well managed, but you and the patient need to know about it. There was some concern about cardiac bleeding events…particularly for patients on anticoagulants, but it is a fairly well-tolerated drug.
Say the patient is 82 years old, and transplant is off the table. [For] low platelet count, you’re giving a low dose of ruxolitinib, [or] you’re giving pacritinib…or fedratinib [Inrebic]. What is the goal of therapy in a patient who’s a non-transplant candidate for whom you’re giving a JAK inhibitor?
ANANTH ARJUNAN, MD: For the patient, the symptom improvement is critical. Along with that getting the spleen [size] down is important, not just for survival benefit, but for the patient to feel better. In terms of discussing treatment options, we go through the different JAK inhibitors, typically based off comorbidities, and then their [blood cell] counts. I haven’t found a reason to use fedratinib. It’s usually a question of ruxolitinib or pacritinib. For clinical trial enrollment, any time is appropriate, although we might wait until they become JAK inhibitor resistant, although you have some options recently with momelotinib.
1. Vonjo. Prescribing information. CTI BioPharma Corp; 2022. Accessed August 29, 2023. https://tinyurl.com/yxjnn7yu
2. Maffioli M, Mora B, Ball S, et al. A prognostic model to predict survival after 6 months of ruxolitinib in patients with myelofibrosis. Blood Adv. 2022;6(6):1855-1864. doi:10.1182/bloodadvances.2021006889