A diagnosis of myelofibrosis without a JAK2, CALR, or MPL mutation should be treated as a red flag, not a final diagnosis. It warrants a deeper investigation for alternative causes, such as MDS/MPN overlap syndromes or secondary fibrosis from other conditions like autoimmune disease or hairy cell leukemia.
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Clinicians can reassure myelofibrosis patients that the drop in hemoglobin often seen when starting ruxolitinib does not carry the same negative prognostic weight as anemia caused by the disease itself. This distinction is crucial for managing patient expectations and continuing effective therapy despite initial side effects.
While beneficial for patients with prior weight loss, ruxolitinib can cause significant weight gain (20-30 pounds) in other myelofibrosis patients. This quality-of-life issue should be discussed proactively, as it can become a major concern, effectively trading one disease state for another.
For myelofibrosis patients with profound splenomegaly but only moderate thrombocytopenia (platelets 50k-100k), fedratinib may be the best frontline option. It is arguably the most potent JAK inhibitor for spleen reduction and is approved for use in patients with platelet counts as low as 50,000.
In patients with systemic mastocytosis and an associated hematologic neoplasm (SM-AHN), the primary clinical challenge is determining which disease component is driving the main problems, such as cytopenias. This is critical because KIT inhibitors treat the SM, but the AHN may require a completely different therapy.
A negative KIT mutation result from standard testing is often unreliable for ruling out systemic mastocytosis (SM). The low variant allele fraction requires highly sensitive assays like digital droplet PCR (sensitive to 0.03%) to avoid false negatives, which can prevent or delay correct diagnosis and treatment.
While quizartinib's benefit is less pronounced in AML patients over 60, a specific genomic signature—the co-occurrence of FLT3-ITD, NPM1, and DNMT3A mutations—identifies a subset of older patients who derive a significant survival benefit, challenging age-based treatment decisions.
While rereading pathology reports is always good practice, it provides the most clinical value in cases of suspected ET. These patients are frequently reclassified as having prefibrotic myelofibrosis, a diagnosis that significantly alters patient counseling, prognosis, and long-term management strategies.
For myelofibrosis patients with both anemia and splenomegaly, a practical approach is to start with ruxolitinib for its superior symptom control. If the subsequent anemia is not well-tolerated, switching to momelotinib allows for a more informed, personalized decision based on the patient's experience with both agents.
The Spanish KIWI trial showed a surprising survival benefit for quizartinib in FLT3-ITD negative AML. The benefit was greatest in patients with NPM1 and DNMT3A mutations, suggesting the drug's efficacy extends beyond its primary target through other mechanisms.
Recurrent non-melanoma skin cancers in patients on ruxolitinib may be attributable to its JAK1 inhibition. In such cases, a viable strategy is to switch the patient to a more JAK2-selective inhibitor, such as pacritinib or fedratinib, to potentially mitigate this specific side effect while maintaining disease control.