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Hey, I am Dr. Lucia Masarova from MD Anderson Cancer Center is Houston, Texas and I will discuss our work presented here in Atlanta at the American Society of Hematology characterizing patients with chronic phase myelofibrosis and elevated blasts between 5 - 9% in the effect of JAK2 inhibitor ruxolitinib.
Myelofibrosis is the most aggressive Philadelphia chromosome negative myeloproliferative neoplasm. Patients mostly present in the chronic phase with less than 10% blasts. Accelerated phase with 10-19% blasts represent an aggressive form of the disease with a very high rate of progression to acute leukemia and poor survival with median less than 12 months.
Ruxolitinib, the only FDA approved JAK2 inhibitor has been shown to improve survival in patients with chronic phase, if know in accelerated phase or acute leukemia post MPN.
Outcome of patients presenting in chronic phase with elevated blasts within 5-9% was unknown. Therefore, we aim to evaluate the clinical characteristics and outcome of these patients and compare them to patients with a chronic phase and less than 5% blasts and those in accelerated phase.
We have retrospectively reviewed of medical charts of almost 1,200 patients presented to MD Anderson Cancer Center over the last 30 years with the diagnosis of myelofibrosis. 70% of patients had primary myelofibrosis and almost 60% were newly diagnosed. Patients were stratified according to the highest blast percentage upon presentation into the groups shown in the table.
The largest graph was patients with the chronic phase and less than 5% blasts. As expected the smallest were patients in accelerated phase and 10-19% blasts. 123 patients presented in the chronic phase with elevated 5-9% blasts accounting for 10% of all study population.
Clinical characteristics and comparison among groups are shown on this slide and demonstrate the patients presented with chronic phase and elevated blasts between 5 to 9% are similar to most of the characteristics to patients in accelerated phase yet significantly different from those in the chronic phase and less than 5% blasts.
Both of these groups were more likely anemic and thrombocytopenic. They get higher white cell and favorable carrier type and higher risk DIPSS. They also had higher incidence of additional known driver molecular mutations.
In terms of therapy 70% of all patients receive at least one treatment during their follow up. Patients with elevated blasts, including those in a chronic phase and elevated blasts between 5 to 9% were likely to be treated with more than three therapists.
Allogenic stem cell transplantation was given to about 9% of all patients with similar distribution among groups. Ruxolitinib was given to one third of all patients and those with a chronic phase involve low as well as elevated blasts were more treated with ruxolitinib and the duration of this therapy was longer.
On the contrary only 11% of patients in accelerated phase received ruxolitinib during their follow up. Ruxolitinib was given as a single agent in 70% of the patients. Remaining of the patients was treated with combinations.
Spleen responses appear to be similar in groups yet direct comparison was impossible due to different treatment regiments.
As we get to outcome of the patients survival shown in the left graph in patients with the chronic phase and the 5 to 9% blasts was similar than survival of patients in accelerated phase, the blue and the red lines.
Median survival of both of these patients was significantly inferior to patients in a chronic phase and less than 5% blast. Acute leukemia progression occurred in 11% of all patients with a higher incidence in those with accelerated phase, yet patients with the chronic phase and elevated blasts between 5 and 9% had still twice as high incidence acute leukemia than patients in the chronic phase and less than 5% blasts.
Treatment with ruxolitinib improved survival in patients in both chronic phases with low as well as elevated blasts as shown on these two graphs, yet not in those in accelerated phase. Patients in chronic phase and less than 5% blasts who were treated with ruxolitinib shown with a black line in the left graph had superior survivor.
Similar, however better improvement in survival, was noticed in patients in a chronic phase and an elevated 5 to 9% blasts. Survival of these patients was twice as high as those without treatment of ruxolitinib within the same groups, 54 versus 27 mans and their survival was similar to those with a chronic phase and less than 5% blast with or without treatment with ruxolitinib. Such a difference was not observed in patients in chronic phase, although graph is not shown.
In conclusion, patients in chronic phase of myelofibrosis who present with 5 to 9% blasts in the bone marrow or peripheral blood have similarly adverse clinical characteristics and inferior survival as patients in accelerated phase. Although the rate of acute leukemia is lower, it's still twice as high as those in the chronic phase and less than 5% blasts. Therefore these patients deserve significant attention in a clinic especially if they did not meet standard criteria for Harris disease according to IPSS score.
Ruxolitinib has improved survival of these patients and their survival reached those with less than 5% blasts, however we don't know the duration of this affect at this point. Therefore new therapies are strongly needed to improve outcome of these patients.
Thank you for your attention and enjoy your presentation.