– Referral to a specialized center with expertise in the management of myeloproliferative neoplasms is strongly recommended for all patients diagnosed with myelofibrosis, according to a new treatment guideline from the National Comprehensive Cancer Network.

The guideline is the first in a series addressing myeloproliferative neoplasms (MPNs), and it focuses on the diagnostic work-up of MPNs, as well as the treatment of myelofibrosis. The guideline panel, led by panel chair Ruben A. Mesa, MD, is working next on guidelines for the other two “core classic” Philadelphia chromosome–negative MPNs: polycythemia vera, and essential thrombocythemia.

Dr. Ruben A. Mesa of the Mayo Clinic Cancer Center, Phoenix Sharon Worcester/Frontline Medical News

Dr. Ruben A. Mesa

Myelofibrosis was addressed first, as it represented the greatest unmet need in terms of guidance, Dr. Mesa said at the annual conference of the National Comprehensive Cancer Network.

Nearly two-thirds of myelofibrosis patients have intermediate-risk 2 or high-risk disease, and treatment decisions in these patients are complex and require patient input – particularly in candidates for allogeneic hematopoietic stem cell transplantation, he said.

“These diseases can be a little different than other malignant diseases,” Dr. Mesa said, explaining that while there is a clear risk of progression to acute myeloid leukemia, and from polycythemia vera and essential thrombocythemia to myelofibrosis, and while the diseases can be fatal, the burden patients face is not solely related to mortality.

There are implications in terms of health that are independent of that, such as the risk of thrombosis and bleeding, the potential for cytopenia, and severe splenomegaly that results in significant symptoms, he said.

Further, while molecular mutations and their implications for prognosis are a “rapidly moving part of the discussion,” the care of patients with MPNs involves far more than a molecular understanding of the disease.

In fact, the role of molecular changes in these patients is speculative, he said.

While such changes can be assessed and used for patient stratification, their role in myelofibrosis – unlike in other diseases such as chronic myeloid leukemia where the level of change in a target gene is highly relevant and prognostic, is not yet clear.

Thus, a core aspect of the guideline is inclusion of the voice of the patient in individualizing care, he said, noting that many factors should be considered, including how well the patient metabolizes drugs, and the symptom profile, psychosocial circumstances, support structure, and personal beliefs.

“It’s not solely about the tumor,” he stressed.

In fact, the answer to the question of whether a patient can be symptomatic enough to require a specific treatment is “no,” because of the potential for side effects, risk, expense, and other considerations.

“So the voice of the patient is always a key part [of the decision],” he said, noting also that as with all NCCN guidelines, this guideline is a partnership with the treating physician; deciding who is a transplant candidate is a nuanced issue for which the panel provides “discussion and guidance.”

“But clearly, these guidelines are the most useful and helpful in the setting of experienced providers bringing all of their experiences to bear,” he said.

In general, however, the guidelines call for allogeneic hematopoietic stem cell transplantation (HCT) in those with intermediate-risk 2 or high-risk disease who are transplant candidates, and treatment based on assessment of symptom burden (using the MPN–Symptom Assessment Form Total Symptom Score–10 Items) in those who are not HCT candidates. Those with platelets at 50,000 or below should be considered for clinical trial enrollment, and those with platelets above 50,000 should be considered for a clinical trial or treatment with the oral JAK1 and JAK2 inhibitor ruxolitinib, which has been shown to have beneficial effects on both symptoms and survival and which is approved for patients with platelets above 50,000. .

Treated patients should be monitored for response and for signs and symptoms of disease progression every 3-6 months. Treatment should continue in those who respond, as well as in those who do not – as long as there is no disease progression.

Those with progressive disease include patients who are moving toward acute leukemia, and those with overt acute leukemia.

“Here is where the key decision occurs. Are they or are they not a transplant candidate? If they are a candidate, we have a potentially curative track which would include cytoreduction followed by transplant,” Dr. Mesa said.

Cytoreduction can involve hypomethylating agents if the patient doesn’t have excess blast cells or too high a burden of disease.

Acute myeloid leukemia–like induction chemotherapy followed by allogeneic HCT is also an option in these patients.

As for treatment of low-risk myelofibrosis, the guideline states that asymptomatic patients can be observed or enrolled in a clinical trial and monitored for progression every 3-6 months, and that symptomatic patients should receive ruxolitinib or interferons (which are used off label), or be enrolled in a clinical trial. Treatment is important for patients with particularly difficult symptoms, he said, noting that some patients have had pruritus so severe that they have committed suicide. Treatment should continue unless monitoring shows signs of progression to intermediate risk 1, intermediate risk 2/high-risk, or advanced stage disease.

For those with intermediate risk 1 disease, the guideline calls for observation or ruxolitinib in those who are symptomatic, or clinical trial enrollment or allogeneic HCT. Treatment should continue unless monitoring shows disease progression, in which case the appropriate algorithm should be considered.

The guideline also addresses several special circumstances, including the management of anemia in myelofibrosis patients, which can be a difficult issue, he said.

Since the guideline was first published in December, two updates have been incorporated, and Dr. Mesa said that he anticipates regular updates given the rapidly evolving understanding of MPNs and new findings with respect to potential treatment strategies.

He noted that a number of drugs are currently in clinical trials involving patients with myelofibrosis, including the JAK2/FLT3 inhibitor pacritinib, the JAK1/JAK2 inhibitor momelotinib, the active antifibrosing agent PRM-151, and the telomerase inhibitor imetelstat, as well as numerous drug combinations.

Going forward, the guideline panel will be focusing on four different areas of assessment, including new therapies and new genetic therapies, improving transplant outcomes, MPN symptom and quality of life assessment, and nonpharmacologic interventions such as yoga.

“We certainly hope to complement things over time, to look not only at pharmacologic interventions, but others that patients may be able to utilize from a toolkit of resources,” he said.

COMFORT-1 update: ruxolitinib responses durable in myelofibrosis

To date, ruxolitinib is the only Food and Drug Administration–approved drug for the treatment of myelofibrosis.

The randomized controlled phase III COMFORT I and II trials conducted in the United States and Europe, respectively, demonstrated that the oral JAK1/JAK2 inhibitor has a rapid, beneficial impact on both survival and disease-associated enlargement of the spleen and improvement in related symptoms, Dr. Mesa said.

A 5-year update on data from 309 patients in the COMFORT-1 trial, as reported at the annual meeting of the American Society of Clinical Oncology in 2016, confirmed the durability of treatment responses to ruxolitinib in patients initially randomized to receive the drug, he said.

“We were able to demonstrate a continued survival advantage for those individuals receiving ruxolitinib,” he added.

At weeks 24 and 264, the mean spleen volume reduction was 31.6% and 37.6%, respectively, in those originally randomized to ruxolitinib. The median duration of at least 35% spleen volume reduction was 168.3 weeks.

Overall survival favored ruxolitinib (hazard ratio, 0.69). Median overall survival in the ruxolitinib group had not yet been reached.

“But we realize our work is not done. The survival curve does not plateau; we are not curing these patients. We’re having meaningful impact, but we have room to continue to improve,” he said.

Also, there is an initial drop in platelet counts that tends to stabilize, but not improve, and there is worsening of anemia (new onset grade 3 or 4 anemia was 25.2% with ruxolitinib, and 26.1% in 111 of 154 patients who crossed over from the placebo group), and although this tends to improve, these are among areas of unmet need, he added.

Further, long-term risks of treatment include cutaneous malignancies (basal cell carcinoma occurred in 7.7% and 9.0% of treatment and crossover patients, respectively), which are difficult to separate from baseline hydroxyurea use, and increased risk of herpes zoster (which occurred in 10.3% and 13.5% of treated and crossover patients).

However, there appears to be no increased risk – and there may be a slight decreased risk – of progression to acute leukemia, Dr. Mesa said.

Dr. Mesa disclosed that he has received consulting fees, honoraria, and/or grant/research support from ARIAD Pharmaceuticals, Celgene, CTI BioPharma, Galena Biopharma, Gilead Sciences, Incyte, Novartis Pharmaceuticals, and Promedior.