Early Study Promising for Ruxolitinib, Decitabine for Myeloproliferative Neoplasms

A phase 1 trial by showed that decitabine with ruxolitinib was generally well tolerated and displayed promising clinical efficacy in patients with accelerated or blast-phase myeloproliferative neoplasms (MPN-AP/BP).

MPN progressing to accelerated and blast-phase disease is associated with extremely poor prognosis, with a median survival of less than 3 months. Treatment with chemotherapy regimens used for acute myeloid leukemia have been rather ineffective, with improvements in survival of only 1 month.

Although there have been limited treatment options in this patient population, 2 of the approaches that demonstrated activity are hypomethylating agents (azacitidine and decitabine) and a JAK1/2 inhibitor (ruxolitinib). Currently, ruxolitinib is not approved alone or in combination with other drugs for the treatment of patients with MPN-AP/BP; however, there have been case reports suggesting synergy with a hypomethylating agent. In this study, investigators tested the safety and efficacy of ruxolitinib with decitabine.

Patients 18 years or older who were recruited had MPN-AP (10%-19% blasts in the peripheral blood or bone marrow) or MPN-BP (≥20% blasts in the peripheral blood or bone marrow). The objective of the trial was to find the optimal dosing of ruxolitinib to be used in combination with decitabine and assess early safety and efficacy endpoints.

From the 21 patients that were in the trial, no signs of drug interactions that affected any of the pharmacokinetic measures were observed. Furthermore, from the 15-mg to 50-mg dose cohorts, the maximum tolerated dose was not reached. Frequent treatment emergent adverse events (TRAEs) that occurred were mainly hematologic, including neutropenia and thrombocytopenia (47.6% each). The most frequent grade 3/4 hematologic TRAEs were neutropenia, lymphopenia, thrombocytopenia, and anemia, and the most frequent grade 3/4 nonhematologic TRAEs were febrile neutropenia, pneumonia, and sepsis.

Of the 17 patients evaluable for response, complete remission with incomplete count recovery was seen in 4 patients, partial remission was seen in 5 patients, and the rest had no response. Overall response rate was 42.9%, 50% with MPN-AP and 38.5% with MPN-BP. Median blast count reductions and median spleen size reductions were 57% and 84.2%, respectively. The largest reductions in blast counts were observed in the 50-mg dose cohort, and the largest reductions in spleen size were observed in the 15- and 25-mg dose cohorts.

The median overall survival (OS) was 7.9 months. Patients with MPN-AP and MPN-BP responders had a median OS of 16 months and 7.2 months, respectively. Median OS was notably higher in responders (10.9 months) compared with nonresponders (7.2 months).

Based on the results of this phase 1 trial, ruxolitinib in combination with decitabine appears to be a safe and tolerable regimen for patients with MPN-AP/BP. A phase 2 trial is ongoing to verify these results in a larger population.

Reference

Rampal RK, Mascarenhas JO, Kosiorek HE, et al. Safety and efficacy of combined ruxolitinib and decitabine in accelerated and blast-phase myeloproliferative neoplasms. Blood Adv. 2018;2(24):3572-3580. doi: 10.1182/bloodadvances.2018019661.