The potential FDA approval of a new biosimilar to trastuzumab may help increase access to the treatment, which is recommended as first-line therapy for patients with ERBB2 (HER2)-positive breast cancer.
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Trastuzumab biosimilar yields similar response rates in breast cancer
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Treatment with the anti-ERBB2 humanized monoclonal antibody trastuzumab, followed by chemotherapy, significantly improves outcomes in patients with ERBB2 (HER2)-positive metastatic breast cancer. But due to its high cost, which is approximately $64,000 for 1 year of treatment, trastuzumab is not widely available for patients in the US or internationally. A biosimilar agent which achieves similar outcomes at a lower cost would enable many patients to have access to affordable, outcome-improving breast cancer treatment.
A randomized clinical trial, led by Hope S. Rugo, MD, University of California San Francisco Helen Diller Family Comprehensive Cancer Center, studied the effects of a proposed trastuzumab biosimilar plus a taxane in patients without prior treatment for ERBB2-positive breast cancer. Researchers compared the overall response rate (ORR) and assessed the safety of the biosimilar to trastuzumab. The study sampled 500 women who were randomly assigned (1:1) to receive the proposed biosimilar or trastuzumab. Chemotherapy was administered for at least 24 weeks followed by antibody alone until the toxic effects or disease progression occurred.
Results of the study showed a 69.6% (95% CI, 63.62%-75.51%) ORR in the biosimilar group and a 64.0% (95% CI, 57.81%-70.26%) ORR in the trastuzumab group. The ORR ratio (1.09; 90% CI, 0.974-1.211) and ORR difference (5.53; 95% CI, −3.08 to 14.04) were within the equivalence boundaries (90% CI, 0.81-1.24 for ratio; 95%, −15 to 15% for difference). Researchers concluded that the use of a proposed trastuzumab biosimilar compared with trastuzumab resulted in an equivalent overall response rate at 24 weeks. Researchers also indicated a need for further study to assess safety and long-term clinical outcomes.
The biosimilar, which is manufactured by Mylan NV (Canonsburg, PN) and Biocon Research Limited (Bangalore, India), is yet to be approved by the FDA. Whether or not this study will be practice-revolutionizing relies largely on the biosimilar’s potential approval as well as whether it will become available to patients currently without access to trastuzumab, a point raised in an editorial accompanying the article, by JAMA Editor in Chief Howard Bauchner, MD, and colleagues.
Financial considerations play a major part in the latter, the authors wrote. This biosimilar is expected to save manufacturing costs because of the ability to leverage preceding research and development using trastuzumab. Drugs like the proposed biosimilar are viewed as a potential solution to the increasing costs of cancer treatment by expanding affordability for many patients.
In wake of an impending FDA approval, the manufacturers of the biosimilar have announced a “shared commitment to increasing access to these critical medicines worldwide” and ability to “enhance access to this affordable therapy to larger patient pools.” To fulfill these promises, the JAMA editors urge Mylan NV and Biocon Research Limited to commit themselves to responsible and fair pricing of their biosimilar.
