An upcoming presentation at the annual American Society of Clinical Oncology (ASCO) meeting promises equal efficacy and much improved safety for patients with early-stage breast cancer receiving Herceptin®. This change in trastuzumab dosing from a 12-month to a 6-month regimen will have ramifications for patients, health systems, and manufacturers.
A number of biosimilar drug makers are trying to be the first to enter the market for trastuzumab. Mylan/Biocon’s Ogivri™ (trastuzumab-dkst) is the only approved agent in the US, but it will not launch before 2019, owing to a licensing agreement with Roche. Amgen/Allergan is expecting word from the Food and Drug Administration (FDA) by May 28th on their own biosimilar version. Samsung Bioepis is also expecting a decision in the fourth quarter of this year. This new study could significantly lower anticipated revenues for these drug makers. The expected pricing pressures of the category (another 2 manufacturers are working through complete response letters from the FDA) will further add to lower revenue.
Trastuzumab Study Results: Half as Long Just as Good
This British study comprised over 4,000 women (median age, 56 yr) who were followed for more than five years. Patients were randomized to receive the originator trastuzumab for either six or 12 months, in addition to usual standard of care. The researchers found that the disease-free survival was 89.8% in the 12-month group compared with 89.4% for the 6-month group. However, the latter showed significantly fewer toxic effects of cancer therapy.
The wholesale acquisition cost for trastuzumab approaches $6,400 per month ($76,700 per 12-mo course). This may lower patients’ out-of-pocket costs, depending on how quickly they reach their cost-sharing maximums. Typically, women taking trastuzumab will be subject to a fixed copay (e.g., $300 per treatment) or a co-insurance (e.g., 20% or $1,280 per month) for this medication alone. Yet, even with the treatment duration being halved, some patients may reach their out-of-pocket maximums. This is the result of office visits, other medications to be taken, and other care related to the toxic side effects of chemotherapy.
Half the Duration but not Half the Costs
For payers and health systems, cost savings will be substantial, but not halved. Most of the costs will be incurred with the first 4 months of weekly therapy. After 12 to 18 weeks, treatments are stretched out to infusions every 3 weeks for the remainder of the regimen. For a 100-kg woman who would receive a total of 5,400 mg of trastuzumab over 52 weeks, this could be reduced to 3,666 mg over 26 weeks (–32%).
The real benefit, should these study results pass scrutiny of peer review and inclusion in practice guidelines, will be in the lower frequency of toxic adverse effects. According to its prescribing information, trastuzumab is associated with “left ventricular cardiac dysfunction, arrhythmias, hypertension, disabling 197 cardiac failure, cardiomyopathy, and cardiac death.” This can occur during therapy (causing discontinuation) or in the years after treatment is completed.
We hope that the good news represented by these study results for patients does not dissuade other manufacturers from seeking biosimilar trastuzumab approval.