Background: Oral tyrosine kinase inhibitors (TKIs) have transformed chronic myeloid leukemia (CML) into a manageable disease, enabling most patients to achieve near-normal life expectancy. As with other specialty drugs, potential hurdles to initiating TKIs include insurer rejection of the prescription, out-of-pocket costs (OOP), and maintaining adherence; however, little real-world evidence exists on these challenges and associated factors. Generic imatinib's impact on patient access and affordability is also understudied. This study aimed to estimate the rates of insurer approval, fill, and adherence to TKIs and associated factors in CML patients.

Methods: This retrospective claims study used the 2021-2023 Symphony Health Solutions Integrated Dataverse database, which uniquely captures whether a prescription submitted to a pharmacy is approved or rejected by the patient's insurer, and filled by the patient. All CML patients with evidence of ≥1 new TKI prescription between 01/01/2022 and 12/31/2022 were included in the sample (index date = date of first TKI prescription). Outcomes included the index TKI approval rate within 90 days of new prescription, index TKI fill rate within 90 days of approval date, and index TKI adherence (defined as a proportion of days covered [PDC]≥0.80) over 6 months after the first fill date. In sensitivity analysis, we expanded the outcomes to measure fill, approval, and adherence to any TKI. Logistic regressions adjusting for insurance plan-level clustering were used to examine factors associated with each outcome. Model covariates included sociodemographics, clinical characteristics, and OOP costs.

Results: The final sample included 2,141 patients (mean age 63.9 y; 48.6% male; 55.3% White), of whom 53.0%, 39.4%, and 7.6% were enrolled in Medicare, commercial insurance, and Medicaid, respectively. Half (50.1%) of the sample received generic imatinib.

Among the 2,141 patients newly prescribed TKIs, 74.7% (n=1600) were approved for their index TKI. Two-thirds (64.1%, 1025 out of 1600) of approved patients filled their index TKI. Less than half (41.9%, 429 out of 1025) of patients who filled their TKI were adherent over 6 months from initiation, representing only 20.0% (429 out of 2,141) of the initial sample. Outcomes based on any TKI were similar (76.4% approval rate, 64.1% fill rate, 45.2% adherence rate). Outcome rates were slightly higher for generic imatinib compared to branded TKIs (76.2% vs. 73.2% approval rate, 67.2% vs. 60.7% fill rate, 46% vs. 37.1% adherence rate).

Compared to commercial patients, Medicare (OR: 3.59, 95% CI 2.64-4.87) and Medicaid (OR: 3.04, 95% CI 1.77-5.21) patients had higher odds of index TKI approval. Other factors associated with approval included older age, residence outside of the northeast, and higher comorbidity index. The only factor associated with the index TKI fill rate was the OOP cost. Compared to patients with OOP ≤$10, higher OOP cost categories were associated with lower odds of filling the index TKI: for example, OR: 0.25 (95% CI: 0.15-0.41) for $100.01 to $250 group, and OR: 0.03, 95% CI 0.02-0.05 for >$2,000 group. Compared to commercial patients, Medicaid patients had higher odds of index TKI adherence (OR: 1.78, 95% CI 1.10-2.85); other factors associated with index TKI adherence included older age and Hispanic ethnicity. No statistically significant difference in any outcome was found between generic imatinib and branded TKIs after adjusting for other factors. Models based on any TKI instead of index TKI showed similar results.

Conclusions: This national, real-world study found that 75% of CML patients newly prescribed a TKI were approved by their insurer; only 60% of approved patients filled their TKI through insurance and only 40% of patients who filled their TKI were adherent over a 6-month period. Insurance type and OOP costs were the strongest factors associated with these outcomes. While our data cannot capture if patients obtained TKIs via manufacturer free-drug programs or direct-to-consumer pharmacy, our findings demonstrate that many patients are unable to access and/or afford these medications despite insurance coverage and generic TKI availability. Legislative efforts may be needed to facilitate access to life-extending therapies such as TKIs, particularly among the commercially insured. Future research should also monitor the impact of recent major policy changes on access and affordability for Medicare and Medicaid patients.

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2025
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