Cost-Effectiveness of Obinutuzumab Plus Chemotherapy Versus Rituximab Biosimilars Plus Chemotherapy for Patients with Previously Untreated Follicular Lymphoma

Background: Obinutuzumab (G) plus chemotherapy (G+chemo) demonstrated greater progression-free survival (PFS) compared with rituximab (R) plus chemotherapy (R+chemo) for patients with previously untreated follicular lymphoma (Marcus, NEJM 2017). G+chemo was shown to be highly cost-effective vs R+chemo, with a cost per quality-adjusted life year (QALY) of $2,300 (Guzauskas, Leuk Lymphoma 2019). The FDA has approved two R biosimilars for use in combination with chemotherapy in this setting, rituximab-abbs (Ra) and rituximab-pvvr (Rp); however, it has not yet been determined if they are cost-effective vs G+chemo. Methods: We used PFS and post-progression survival data from the GALLIUM trial to model overall survival for G+chemo vs R+chemo using an existing Markov model. Efficacy and safety equivalence were assumed for R-biosimilars+chemo and the R+chemo arm, with drug utilization, treatment duration, and adverse events (AEs) also based on GALLIUM trial data (data cutoff February 2018). Costs for drugs, drug administration, AEs, and treatment following disease progression were included. QALYs were estimated from utility estimates based on GALLIUM trial data and published literature. Sensitivity analyses assessed key drivers of the model and uncertainty in the results. Results: The total cost of G+chemo was $197,211, while the costs of Ra+chemo and Rp+chemo were $190,238 and $178,997, respectively. This corresponded to incremental costs of $6,974 and $18,214, for G+chemo vs Ra+chemo and Rp+chemo, respectively. The average total cost was higher for G+chemo, mainly due to increased drug and administration costs ($128,103 for G+chemo vs $114,640 for Ra+chemo and $103,399 for Rp+chemo); however, this was largely offset by cost-savings for disease progression of $7,839. An increase in QALYs of 0.93 was calculated for treatment with G+chemo relative to R-biosimilars+chemo. The incremental cost-effectiveness ratios were $7,465 and $19,498 per QALY gained for G+chemo vs Ra+chemo and Rp+chemo, respectively. In probabilistic sensitivity analyses, G+chemo was cost-effective at the $100,000 per QALY threshold vs both Ra+chemo and Rp+chemo (99.4% and 98.7% probabilities, respectively). Conclusions: As a result of delayed progression treatments and increasing QALYs, these data indicate that G+chemo is likely cost-effective in the US as first-line therapy for follicular lymphoma, despite the lower cost of R-biosimilars compared with R. Acknowledgements: GALLIUM was sponsored by F. Hoffmann-La Roche Ltd. Third-party editorial assistance, under the instruction of the authors, was provided by Katie Smith, Gardiner-Caldwell Communications, and was funded by F. Hoffmann-La Roche Ltd.