OBJECTIVES : This economic evaluation assessed the incremental cost-effectiveness ratio (ICER) of induction with obinutuzumab (G) plus chemotherapy followed by G maintenance (G-chemo) compared with rituximab (R) plus chemotherapy followed by R maintenance (R-chemo) for the treatment of high-risk patients (high/intermediate FLIPI score) with previously untreated follicular lymphoma (FL) from the Canadian healthcare perspective, based on the Phase III GALLIUM study.

METHODS : A Markov model was created to estimate the cost-utility of treatment with G- versus R-chemo over a lifetime horizon. It included four health states (progression-free survival [PFS], early progressive disease [PD, including PD within 24 months; POD24], late PD, and death) to capture differences in costs (2018 Canadian dollars) and outcomes for these patients. The chemotherapy regimen (CHOP, CVP or bendamustine) was chosen upfront by the participating centers.

The model used the latest GALLIUM trial data (February 2018) for the pre-specified high/intermediate FLIPI population (n=950). The base case incorporated the primary outcome, investigator-assessed PFS (4-year PFS: 78.16 % vs 64.37% for G-chemo [n=474] vs R-chemo [n=476], respectively [hazard ratio (HR)=0.65, 95% confidence interval 0.52–0.82, p=0.0003]). Median PFS was not reached in either arm (median follow-up 4.12 years). PFS was extrapolated using parametric survival functions, assuming proportional constant hazards until treatment effect was capped at 9 years, resulting in median PFS estimates of 9.6 versus 6.4 years for G-chemo versus R-chemo, respectively (estimated median difference 3.2 years). Post-progression survival was informed by GALLIUM based on rates observed for POD24 patients and those progressing after 24 months.

RESULTS : In the base case, G-chemo led to an ICER of $36k/Quality-Adjusted Life-Year (QALY) versus R-chemo in high/intermediate FLIPI score patients. In a sensitivity analysis, with chemotherapy regimens weigh ted to reflect Canadian clinical practice, the ICER was $29k/QALY.

CONCLUSIONS : G-chemo may be a cost-effective option for first-line high-risk patients with FL in Canada.