Prior authorizations for oral anticancer drugs and delayed prescription fills.

Abstract

1504 Background: Oral anticancer drugs have proliferated in recent decades. These drugs are increasingly approved based on provisional data via the FDA’s accelerated approval pathway and have high prices, motivating payers to closely monitor how they are used. We assessed use of prior authorization (PA) of oral cancer drugs for Medicare Part D beneficiaries and assessed the impact of PA on delays in prescription fills. Methods: Using Medicare Part D formulary and claims data from 2010-2019, we described trends in Part D plans’ use of PA for oral oncology drugs, identified using the Oncology Care Model drug list (excluding hormonal therapies). We then examined changes in access to imatinib after the introduction of a new PA. We focused on imatinib because it is a highly effective first-in-class drug with a generic entrant in 2016. We compared Part D beneficiaries continuously enrolled in a plan with a policy change (new PA introduced) or a control plan (no change) in the 120 days before and after the policy change or equivalent date (control) and had at least three 30-day imatinib fills in the pre period. This restriction aimed to identify individuals filling regularly and plausibly expected to continue the drug. For each index fill in the post period, we calculated predicted fill (date of previous fill + days supply received). Our outcome variable was the difference (in days) between predicted and observed index fill date, censored at 120 days for post-period observations without an observed fill. We used an event study to model predicted vs. actual time to first fill following a policy change (new PA) relative to the controls (no change), adjusting for patient age, sex, low-income subsidy, average number of days between pre-period fills, year of fill, and plan type (standalone or Medicare Advantage). Results: The proportion of oral anticancer drugs requiring a PA increased from 52.8 to 96.3% from 2010 to 2019. For imatinib, PA increased from 65% to 89% from 2010-16, the year generic imatinib entered. PA for generic imatinib was 95% on market entry. In the imatinib event study sample, there were 1,354 index fills for patients. Unadjusted mean delay in index fill was 40 days for new PA and 15 days for controls; median difference was 4 and 3 days, respectively. Discontinuation was comparable: 9.3% (new PA) vs. 9.5% (control). The adjusted difference between predicted and actual fills for new PA was 20.3 days (95% CI 6.5-34.2, p<0.004). Conclusions: Use of PA for oral oncology drugs has increased substantially over 10 years. In the setting of high prices and provisional outcomes data, PA may be appropriate. However, PA may delay fills, even for high-value drugs like imatinib. Oral anticancer drug adherence is an NCI priority; further study is warranted to identify opportunities to reduce administrative burden of PA and lessen barriers in access to effective medications.