Cost-efficiency analysis of conversion to biosimilar filgrastim for supportive cancer care and resultant expanded access analysis to supportive care and early-stage HER2+ breast cancer treatment in Saudi Arabia: simulation study.

Aims: This study estimated, for Saudi Arabia, the cost-efficiency of converting patients from reference Neupogen and Neulastim to one of two filgrastim biosimilars (Nivestim, Zarzio); the budget-neutral expanded access to supportive care with biosimilar filgrastim and therapeutic care to ado-trastuzumab emtansine thus afforded; and the number-needed-to-convert (NNC) to provide supportive or therapeutic treatment to one patient.

Materials And Methods: Replicating prior studies, we modeled the cost-efficiencies gained from converting varying proportions of a hypothetical panel of 4,000 patients undergoing six cycles of cancer treatment from Neupogen or Neulastim to one of the two biosimilar G-CSF formulations, using national cost inputs. Cost-savings in USD were used to estimate the additional doses of biosimilar G-CSF and expanded access to ado-trastuzumab emtansine on a budget-neutral basis, and NNC to purchase one additional dose of supportive or therapeutic treatment.

Results: Savings from conversion from reference to a biosimilar filgrastim were $3,086,400 (Nivestim) and $3,460,800 (Zarzio). With reference pegfilgrastim, savings from conversion were $11,712,240 (Nivestim) and $12,086,640 (Zarzio). Biosimilar conversion from reference to biosimilar filgrastim enabled expanded access to ado-trastuzumab emtansine ranging from 61 patients (5 days, Nivestim) to 191 patients (14 days, Zarzio). For supportive care, biosimilar conversion enabled expanded access ranging from 8,244 patients (5 days, Nivestim) to 25,882 patients (14 days, Zarzio). For biosimilar conversion from daily filgrastim, the NNC for treatment with ado-trastuzumab emtansine decreased as days of injections increased [5 days: 395 (Nivestim), 352 (Zarzio); 14 days: 141(Nivestim), 126 (Zarzio)]. Alternately, for biosimilar conversion from single-injection pegfilgrastim to daily biosimilar filgrastim, the NNC for treatment with ado-trastuzumab emtansine rose as days of injections increased, being highest under the 14-day scenario (146, Nivestim; 130, Zarzio).

Conclusion: This simulation study demonstrated significant potential cost-savings from biosimilar conversion. These savings provide budget-neutral increased access to supportive and therapeutic cancer care.