OBJECTIVES: Mosunetuzumab (Mosun), a novel CD20xCD3 T-cell engaging bispecific antibody, has received accelerated approval by the US Food and Drug Administration for adult patients with R/R FL after at least 2 prior therapies (3L+). We sought to evaluate the cost-effectiveness of Mosun for the treatment of 3L+ R/R FL from a US-payer perspective.

METHODS: A three-state (progression-free, progression, death) partitioned-survival model was developed to simulate the lifetime costs and outcomes of Mosun against 7 comparators: axicabtagene ciloleucel (axi-cel), tisagenlecleucel (tisa-cel), tazemetostat (taz, EZH2 wild-type only), rituximab in combination with lenalidomide (R-Len) or bendamustine (R-Benda), obinutuzumab in combination with bendamustine (O-Benda), and 3L+ FL treatments used in routine care by a retrospective real-world cohort (RW). Efficacy data for Mosun were from the GO29781 trial (NCT02500407). The real-world cohort data were derived from a US electronic health record database (Flatiron Health). The relative efficacy of Mosun vs. the comparators was estimated from indirect treatment comparisons (ITCs). Costs (inflated to 2022 US dollars) included US-specific costs associated with treatment, adverse events, routine and terminal care. Costs and quality-adjusted life years (QALYs) were used to calculate incremental cost-effectiveness ratios (ICERs). For cases where a new treatment was lower in cost and less efficacious, the net monetary benefit (NMB) was calculated. A willingness to pay (WTP) threshold of $150,000 per QALY was used to assess cost-effectiveness.

RESULTS: Mosun dominated taz, tisa-cel, and axi-cel with greater QALYs and lower costs. Mosun was cost-effective against R-Benda, O-Benda, and RW with ICERs of $78,604, $42,736, and $21,521, respectively. Mosun incurred lower costs but lower QALYs vs. R-Len. The NMBs at the $150,000 WTP per QALY showed that Mosun was cost-effective against all comparators except R-Len.

CONCLUSIONS: Mosun is projected to be cost-effective compared with most approved regimens for the treatment of adults with 3L+ R/R FL.