Generic Drugs Increase Adherence to Life-Saving Breast Cancer Treatment

Dispensing generic hormonal therapies instead of their brand-name counterparts increases breast cancer patients’ life-saving medication adherence by 50%, according to a study published in the October 2014 issue of the Journal of the National Cancer Institute.

Researchers from Columbia University Medical Center observed 5511 women aged 50 years or older with early-stage breast cancer who filled a prescription for a brand-name aromatase inhibitor (BAI) and/or a generic aromatase inhibitor (GAI) between January 1, 2007, and December 31, 2012.

Among the patients, 2815 (51.1%) were taking BAIs, which included Arimidex, Femara, and Aromasin; 1411 (25.6%) were on GAIs, which included anastrozole, exemestane, and letrozole; and 1285 (23.3%) switched from BAIs to GAIs. Of those who started with BAIs prior to the availability of generic alternatives, 73.2% switched to GAIs after they became available.

The investigators defined adherence as a medication possession ratio (MPR) of 80% or greater throughout the first 2 years of therapy, and they categorized patients with a minimum 45-day supply gap with no hormone therapy on hand as having discontinued treatment.

In the study, the researchers determined that patients who received a GAI were less likely to discontinue therapy than those who received a BAI. Additionally, the investigators noted that even a small increase in monthly co-pays negatively affected treatment adherence, as patients with monthly co-pays of $15 to $30 were more likely to discontinue treatment than with those with monthly co-pays under $15. The median monthly co-pay was higher for BAIs ($33.30) than GAIs ($9.04).

“Our findings suggest that more effort should be made to reduce out-of-pocket costs for these potentially life-saving medications,” said study leader Dawn L. Hershman, MD, MS, in a press release. “This is especially important given the rapid increase of expensive oral cancer therapies.”

However, Dr. Hershman noted that cost is not the only factor that influences a patient’s medication adherence, as up to 40% of women taking hormone therapy experience joint stiffness that often leads to treatment discontinuation.

“If you add a high co-payment to the mix, that's often enough to make them discontinue therapy,” Dr. Hershman stated.

Given the growing realm of costly oral biologic cancer therapies, the researchers believe medication nonadherence will likely expand among breast cancer patients. They noted that the average monthly costs of BAIs and GAIs are $380 and $150, respectively, while the average monthly cost of oral biologics ranges from $5000 to $8000.