Effective brand-name drugs carry patents that allow pharmaceutical companies to charge high prices for their medications, which in turn generate profits and incentives to develop new products. However, the high prices for brand-name drugs can be a cost barrier for patients who need them, which could limit the appeal and use of even the most beneficial drugs. Generic drugs offer cheaper access to treatment, but they’re not available until after the yearslong patents on brand-name medications expire. To see how the entry of generic drugs into the market influences its popularity and use, School of Public Health researchers tracked the introduction of three generic oral breast cancer drugs and found it meant patients were more likely to choose them and begin therapy sooner.

The study was led by recent graduate Xuanzi Qin (PhD ‘20) and published in the journal Research in Social and Administrative Pharmacy. SPH Professors Peter Huckfeldt, Beth Virnig, and Jean Abraham, and Medical School Professor Douglas Yee co-authored the paper.

The study reviewed the Medicare pharmacy claims for 93,650 older (65+) female Medicare patients diagnosed with hormone receptor-positive (HR+) breast cancer — the predominant form of the disease — between 2007 and 2013. HR+ breast cancer is typically treated with either oral aromatase inhibitors or tamoxifen, with aromatase inhibitors preferred over tamoxifen due to higher effectiveness. During the study period, tamoxifen was available as a generic drug and the three main forms of aromatase inhibitors were released in generic form between 2010 and 2011. The researchers specifically examined the percent of patients beginning treatment with aromatase inhibitors or tamoxifen within one year of diagnosis, the actual time from diagnosis to starting treatment, and the initial choice of therapy.

The study found that:

• Treatment initiation rates increased from 69.5% before generic drug options to 74.3% after they became available.
• With the availability of generic drugs, the estimated time to treatment initiation decreased by 0.3 months from 4.1 months to 3.8 months following diagnosis.
• The probability of choosing aromatase inhibitors over tamoxifen increased by 5.9% once they were available in generic form.

“Overall, when the generic drugs became available, more people started treatment, they did it sooner, and they started choosing aromatase inhibitors more,” says Qin. 

The study also compared the changes of access after generic entry between women who received Medicare Part D low-income subsidies versus those who did not. 

“Beneficiaries receiving the subsidy have reduced Part D premiums, deductibles, and copayments,” says Qin. “While the median out-of-pocket costs for 30-day supply of aromatase inhibitors decreased by around $30, the reduction was only around $2 for those receiving subsidies.”

The price reduction lowered the cost of aromatase inhibitors to roughly the same price as the once-cheaper tamoxifen. Importantly, the study found that even those women who received cost subsidies and only had a small reduction in costs were more likely to initiate the therapy after generic entry of aromatase inhibitors.

All the same, after generic drugs became available, there were still approximately 25% of women diagnosed with HR+ breast cancer who never started the beneficial therapy. 

“Together, the results suggest that costs are not the sole determinant of whether women will begin using a drug,” says Qin.

The researchers say that policymakers should be aware that reducing costs cannot solve all access problems and they need to pay attention to any non-financial barriers to use, such as concerns about drug toxicity and other health issues. Their advice to clinicians is to be aware of the availability and out-of-pocket cost of drugs in order to help patients learn about their treatment choices and choose what works best for them. Clinicians should also be aware that there are programs to help lower-income Medicare recipients with their pharmacy costs.

Qin and the researchers are now examining whether the availability of generic drugs increased switching from among different aromatase inhibitors to manage treatment-related adverse events, and if it influenced adherence or discontinuation of therapy.