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Avapritinib Adoption for GIST Demonstrates Minimal Budget Impact on US Health Plan

January 12, 2021

The adoption of avapritinib as a treatment option for metastatic or unresectable gastrointestinal stromal tumors (GIST) would have a minimal budget impact to a hypothetical US health plan (JAMA Netw Open. 2020;3[11]:e2025866. doi:10.1001/jamanetworkopen.2020.25866).

David Proudman, MBiochem, MPH, Analysis Group Inc, Menlo Park, California, and colleagues conducted an economic evaluation in order to estimate the budget impact of introducing avapritinib to a formulary for metastatic or unresectable GIST in patients with a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 variant or who have received 3 prior therapies from the perspective of a US health plan.

“Before the availability of avapritinib, effective treatment options for patients with GIST and the PDGFRA exon 18 variant were lacking, leading to a poor prognosis for these patients” reported Mr Proudman and colleagues.

“Health plans need tools to assess the economic impact and plan for future spending,” they added. 

In March 2020, a 3-year budget impact model was developed and included costs for drug acquisition, testing, monitoring, adverse events, and postprogression treatment. The model assumed avapritinib adoption would be associated with increased PDGFRA testing rates. Scenarios with and without avapritinib in a formulary were compared.

A hypothetical health plan that included 1 million members was used with an assumed population of 69% commercial, 22% Medicare, and 9% Medicaid.

The main outcome measures of the study were annual, total, and per member per month (PMPM) budget impact.

Overall, less than 0.1 new patients with a PDGFRA exon 19 variant per year and 1.2 patients receiving fourth-line therapy per year were eligible for treatment.

With the availability of avapritinib, the total costs increase in year 3 was $46,875 ($0.004 PMPM) for all eligible patients with a PDGFRA exon 18 variant and $69,182 ($0.006 PMPM) for patients undergoing fourth-line therapy. The total budget impact in year 3 amounted to $115,604 ($0.010 PMPM) and included postprogression costs avoided or delayed of $3607.

Additionally, higher rates of molecular testing resulted in a minimal incremental cost increase of $453 in year 3.

“These results suggest that adoption of avapritinib as a treatment option would have a minimal budget impact to a hypothetical US health plan,” concluded Mr Proundman and colleagues.

“This would be primarily attributable to the small eligible patient population and cost offsets from reduced or delayed postprogression costs,” they added.—Marta Rybczynski

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