Financial Implications of Avapritinib for Treatment of Unresectable Gastrointestinal Stromal Tumors in Patients With a PDGFRA Exon 18 Variant or After 3 Previous Therapies in a Hypothetical US Health Plan

Abstract

IMPORTANCE With the approval of avapritinib for adults with unresectable or metastatic gastrointestinal stromal tumors (GISTs) harboring a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 variant, including PDGFRA D842V variants, and National Comprehensive Cancer Network guideline recommendations as an option for patients with GIST after third-line treatment, it is important to estimate the potential financial implications of avapritinib on a payer's budget. OBJECTIVE To estimate the budget impact associated with the introduction of avapritinib to a formulary for metastatic or unresectable GISTs in patients with a PDGFRA exon 18 variant or after 3 or more previous treatments from the perspective of a US health plan. DESIGN, SETTING, AND PARTICIPANTSFor this economic evaluation, a 3-year budget impact model was developed in March 2020, incorporating costs for drug acquisition, testing, monitoring, adverse events, and postprogression treatment. The model assumed that avapritinib introduction would be associated with increased PDGFRA testing rates from the current 49% to 69%. The health plan population was assumed to be mixed 69% commercial, 22% Medicare, and 9% Medicaid. Base case assumptions included a GIST incidence rate of 9.6 diagnoses per million people, a metastatic PDGFRA exon 18 mutation rate of 1.9%, and progression rate from first-line to fourth-line treatment of 17%. EXPOSURESThe model compared scenarios with and without avapritinib in a formulary.MAIN OUTCOMES AND MEASURES Annual, total, and per member per month (PMPM) budget impact. RESULTSIn a hypothetical 1-million member plan, fewer than 0.1 new patients with a PDGFRA exon 18 variant per year and 1.2 patients receiving fourth-line therapy per year were eligible for treatment.

The immunotherapy in gastrointestinal stromal tumors

“…Limitations of the study include its retrospective nature, potential biases inherent in observational studies, and the indirect comparison between different treatment regimens. [ 18 ] The study population included adults with unresectable or metastatic gastrointestinal stromal tumors (GISTs) harboring a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 variant or those who had undergone 3 or more previous treatments. The treatment under consideration was avapritinib, which was approved for adults with unresectable or metastatic GISTs harboring PDGFRA exon 18 variants.…”

“…A new generation of second-, third-, and fourth-line GIST treatments has emerged with sunitinib, regorafenib, and ripretinib, respectively [ [13] , [14] , [15] , [16] ]. Additionally, avapritinib has received recent FDA approval [ 17 , 18 ]. A two-decade-long revolution has occurred in GIST treatment with the introduction of imatinib and subsequent tyrosine kinase inhibitors (TKIs), providing a significant survival advantage by delaying metastases and recurrences.…”

Budget impact analysis of trilaciclib for decreasing the incidence of chemotherapy-induced myelosuppression in patients with extensive-stage small cell lung cancer in the United States

“…Finally, only grade ≥ 3 AEs were considered within the AE management cost estimates, which may underestimate the health and economic impact of trilaciclib. Although there is no consensus on which AEs to include, economic models typically focus on grade ≥ 3 AEs, [65][66][67][68] as these are most likely to require resource utilization and have a meaningful impact on the results. Moreover, although lower-grade AEs may require medical services in some cases, consideration of all AEs would require additional model assumptions, 30,65 which may reduce confidence in the model.…”

Advances in immunology and immunotherapy for mesenchymal gastrointestinal cancers

“…Recently, the Food and Drug Administration (FDA) of the United States approved sunitinib, regorafenib and ripretinib as the second-, third- and fourth-line drugs for GIST, respectively, which prolong the mPFS of metastatic or recurrent patients with 5.6 [ 29 ], 4.8 [ 30 ] and 6.3 [ 31 ] months, respectively. Avapritinib was also recently approved by the FDA, and the mPFS is 29.5 months in metastatic PDGFRA-D842V GIST patients [ 32 ], and 3.7 months in non-D842V GIST patients [ 33 ].…”