PFS improvement will translate to OS, speaker says
SAN FRANCISCO—Administering brentuximab vedotin immediately after autologous stem cell transplant can improve progression-free survival (PFS) in patients with Hodgkin lymphoma (HL), results of the phase 3 AETHERA trial suggest.
The overall survival (OS) data for this study are not yet mature, but the significant improvement in PFS will likely translate to improved OS in a few years’ time, according to Craig Moskowitz, MD, of Memorial Sloan Kettering Cancer Center in New York.
Dr Moskowitz presented results from the AETHERA trial at the 2014 ASH Annual Meeting as abstract 673. The trial was funded by Seattle Genetics, Inc., and Takeda Pharmaceutical Company Limited, the companies developing brentuximab.
The trial included HL patients with at least one risk factor for progression. Eligible patients must have had a history of refractory HL, relapsed within a year of receiving frontline chemotherapy, and/or had disease outside of the lymph nodes at the time of pre-transplant relapse.
Researchers enrolled 329 patients, and they were randomized to receive brentuximab or placebo every 3 weeks for up to about a year. Baseline characteristics were similar between the 2 arms.
Dr Moskowitz pointed out that 43% of patients in the brentuximab arm and 48% in the placebo arm had required 2 or more prior salvage therapies, and 60% and 59%, respectively, had primary refractory HL.
Patients in both arms received a median of 15 treatment cycles, with an average of 12 cycles on the brentuximab arm and 11 cycles on the placebo arm.
“Patients who progressed in the placebo arm could be unblinded and subsequently receive brentuximab on a companion study,” Dr Moskowitz noted. “So technically, this was a cross-over design, making overall survival at 24 months quite unlikely.”
Efficacy/survival results
About half of patients in each arm completed treatment—47% in the brentuximab arm and 49% in the placebo arm. The reasons for discontinuation included disease progression (15% and 42%, respectively), adverse events (33% and 6%, respectively), and patient decision (5% and 2%, respectively).
Still, the trial achieved its primary endpoint, demonstrating a significant increase in PFS, according to an independent review facility (IRF).
The median PFS per the IRF was 43 months for patients in the brentuximab arm and 24 months in the placebo arm (hazard ratio=0.57, P=0.001). The 2-year PFS rates per the IRF were 63% and 51%, respectively.
The 2-year PFS rate according to investigators was 65% in the brentuximab arm and 45% in the placebo arm. The median PFS per investigators has not yet been reached for brentuximab but was 16 months for placebo.
The PFS benefit was consistent across all pre-specified subgroups, Dr Moskowitz noted, including primary refractory patients, patients who relapsed within 12 months of frontline therapy, and patients who relapsed after 12 months with extranodal disease.
Patients who experienced disease progression received a variety of subsequent therapies.
In the brentuximab arm, 16% of patients receiving subsequent therapy were treated with brentuximab after relapse. In the placebo arm, 85% of patients receiving subsequent therapy were treated with single-agent brentuximab.
Twenty-eight percent of patients in the placebo arm and 25% in the brentuximab arm received stem cell transplant as subsequent therapy, the majority of which were allogeneic transplants. Dr Moskowitz said a second transplant could have improved survival in these patients, but whether it actually did is unclear.
He noted that the OS data are immature, but there is currently no significant difference in OS between the treatment arms (hazard ratio=1.15; P=0.62).
“The median follow-up right now is 24 months,” he said. “So one will have to wait for a survival advantage or disadvantage, but from my point of view, a PFS of 65% at 2 years will translate to an overall survival difference. We’re just going to have to wait a few more years.”
