Updated Efficacy and Safety Data from the AETHERA Trial of Consolidation with Brentuximab Vedotin after Autologous Stem Cell Transplant (ASCT) in Hodgkin Lymphoma Patients at High Risk of Relapse

Introduction

The AETHERA trial is a phase 3, randomized, placebo-controlled trial (ClinicalTrials.gov #NCT01100502), which evaluated whether post-ASCT consolidation treatment with brentuximab vedotin (BV) could prevent disease progression in Hodgkin lymphoma (HL) patients at high risk for relapse. The study met its primary endpoint: significant improvement in progression-free survival (PFS) per independent review with BV versus placebo (hazard ratio [HR]=0.57, P=0.001) (Moskowitz, 2015). The 2 most common adverse events (AEs) in the BV- treatment group were peripheral sensory neuropathy (56%) and neutropenia (35%). We are presenting updated efficacy and safety data after approximately 1 additional year of follow-up after the primary analysis.

Methods

Patients were randomized to receive BV 1.8 mg/kg q3wk or placebo for 16 cycles (approximately 12 months), 30–45 days after transplantation. Randomization was stratified by response to frontline therapy and by best clinical response to pre-ASCT salvage therapy. Patients whose disease had progressed after salvage treatment were not eligible. Patients received CT scans quarterly for the first year and then at 18 and 24 months during long-term follow-up (LTFU). Clinical lymphoma assessments were performed at each cycle of treatment, quarterly during the first year of LTFU, and every 6 months thereafter. AEs were collected for 30 days after the end of treatment, except for peripheral neuropathies and secondary malignancies, which were followed throughout LTFU.  Clinical responses to subsequent BV treatment received after progression were also recorded.

Results

A total of 329 patients were randomized to the BV- (n=165) or placebo- (n=164) treatment arms. Median PFS per investigator assessment was not reached (95% CI not estimable [NE]–NE) in the BV arm and was 15.8 months (95% CI 8.5–44.0) in the placebo arm (HR=0.52, 95% CI 0.37–0.71). A sustained plateau with substantial separation is evident between both treatment groups, with improved PFS at 3-years post-randomization with BV consolidation versus placebo (Figure). The 3-year PFS rate was 61% (95% CI 52–68) for the BV arm and 43% (95% CI 36-51) for the placebo arm. Six PFS events (2 progressions and 4 deaths) were recorded after the 24-month evaluation period in the BV arm and 3 in the placebo arm (2 progressions and 1 death). The HR for PFS per independent review was 0.58 (95% CI 0.41–0.82).

No new secondary malignancies have been observed since the primary analysis. The number of cases were comparable between the 2 treatment arms (n=4 BV, n=2 placebo). Malignancies on the BV arm included bladder cancer, lung cancer, pancreatic cancer, and myelodysplastic syndrome (n=1 each). In the placebo arm, secondary malignancies included mantle cell lymphoma and myelodysplastic syndrome (n=1 each). Among the 112 patients on the BV arm who experienced treatment-emergent peripheral neuropathy based on a Standardised Medical Dictionary for Regulatory Activities (MedDRA) Query (SMQ) analysis, 99 patients (88%) experienced some improvement (23%) or complete resolution (65%) of neuropathy symptoms at the time of analysis. Discontinuation of treatment due to an AE occurred in 54 patients (33%) on the BV arm, most commonly due to peripheral sensory and motor neuropathies (14% and 7%, respectively). Patients who discontinued treatment as a result of an AE received a median of 9.5 cycles (range, 1 to 15) on the BV arm.  The 2-year PFS rate in these patients was 69% (95% CI 54–79) versus 82% (95% CI 71–89) for patients who completed all 16 treatment cycles.

Conclusions

Consolidation treatment with BV in HL patients at high risk of relapse after ASCT showed an improvement in PFS versus placebo, approximately 3 years since the last patient was randomized. Kaplan-Meier analysis of PFS per investigator assessment showed a continued benefit of BV consolidation. No additional secondary malignancies have been observed in either treatment arm and most patients experienced resolution of peripheral neuropathy symptoms. We are currently analyzing clinical responses to BV treatment after disease progression.

Figure: Progression-Free Survival per Investigator Assessment