the 2014 ASH Annual Meeting
SAN FRANCISCO—Combination therapy with ruxolitinib and panobinostat shows signs of efficacy in myelofibrosis (MF), according to research
presented at the 2014 ASH Annual Meeting.
“Targeting multiple components of the JAK/STAT pathway, as well as parallel signaling pathways that may also be involved in the pathogenesis of myelofibrosis, has the potential to have a synergistic therapeutic effect on the underlying disease,” said Jean-Jacques Kiladjian MD, PhD, of the Hôpital Saint-Louis and Université Paris Diderot in Paris, France.
Ruxolitinib, a potent JAK1/JAK2 inhibitor, demonstrated rapid and durable reductions in splenomegaly and MF-related symptoms, improved quality of life, and provided a survival advantage in the phase 3 COMFORT studies.
Panobinostat, a potent oral pan-deacetylase inhibitor, reduced spleen size, symptoms, and JAK2V617F allele burden in patients with MF in phase 1 and phase 2 studies.
The combination of ruxolitinib and panobinostat demonstrated synergistic anti-MF activity in a phase 1b study.
At ASH, Dr Kiladjian presented updated results from the expansion phase of this trial (abstract 711). This study was sponsored by Novartis, the company developing ruxolitinib.
The treatment schedule was ruxolitinib at 5 mg to 15 mg twice daily and panobinostat at 10 mg to 25 mg once daily 3 times per week on days 2, 4, and 6 every other week in a 28-day cycle.
A dose-escalation phase included 38 patients with a median age of 63 years, and an expansion phase included 23 patients with a median age of 67 years.
The recommended phase 2 dose was 15 mg of ruxolitinib twice daily and 25 mg of panobinostat twice weekly, every other week.
“Changes in spleen size were seen in the escalation phase, even at low doses,” Dr Kiladjian said. “Some patients completely eliminated splenomegaly.”
The expansion phase showed similar results. At 24 weeks, more than 85% of patients had a 50% or greater reduction in splenomegaly. Some 59% of patients achieved a 50% or greater reduction in palpable spleen length.
“We saw some JAK2 inhibition and reduction in bone marrow fibrosis, as well as significant reduction in several cytokines related to inflammation,” Dr Kiladjian said.
The most common hematologic adverse events were anemia and thrombocytopenia. There were few neutropenias.
“We saw quite remarkably stable levels of hemoglobin and platelets,” Dr Kiladjian said.
Non-hematologic adverse events were primarily gastrointestinal toxicity associated with panobinostat, including grade 3 or 4 diarrhea and asthenia.
“The rates of adverse events observed in this trial are in line with the expected and known adverse events of these 2 agents when used as monotherapies,” Dr Kiladjian said.
“The combination of ruxolitinib and panobinostat was well-tolerated and resulted in substantial reductions in splenomegaly. Most patients treated at the [recommended phase 2 dose] of combination therapy achieved a spleen response.”
Dr Kiladjian therefore encouraged further exploration of this “favorable” combination.
