The importance of these findings cannot be underscored sufficiently. The development of a biosimilar for treatment in this setting could mean not only lower health-care costs for society overall, but also greater access to an important life-saving or life-extending drug for a larger breast cancer population across the globe.— Chau T. Dang, MD
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The human epidermal growth factor receptor (HER) family consists of four members—epidermal growth factor receptor (EGFR), HER2, HER3, and HER4—all transmembrane receptor tyrosine kinases, which regulate cell growth and survival, differentiation, and migration, as well as other cellular responses.1 HER2 protein was shown to be highly expressed in approximately 20% of breast tumors as a result of amplification of the HER2 gene. Its overexpression portends an aggressive natural history compared to other breast tumors.2
Since the approval of trastuzumab (Herceptin) in 1998 for the treatment of HER2-positive metastatic breast cancer, the natural history of HER2-positive breast cancer has been significantly altered, with patients now living longer with a disease that was once much more difficult to treat.3 Trastuzumab also led to a significant improvement in disease-free and overall survival in patients with early-stage disease and was approved in this setting in 2006.4
According to the World Health Organization’s List of Essential Medicines, trastuzumab is one of the most effective and safe treatments needed in a health system.5 However, it must be emphasized that trastuzumab is not as readily available in many countries as it is in the United States.6 As such, many companies worldwide are developing trastuzumab biosimilars, with patents on the drug having expired in 2014 in Europe and due to expire in 2019 in the United States.7
As reviewed in this issue of The ASCO Post, in a recent JAMA article, Rugo et al reported the results of a phase III equivalence trial—the Heritage study—and demonstrated that treatment with the proposed trastuzumab biosimilar (MYL 1401O) was equivalent to trastuzumab, both in combination with a taxane, in terms of overall response rates at 24 weeks in patients with previously untreated metastatic HER2-positive breast cancer.8 At 48 weeks, there were no differences in time to progression or progression-free or overall survival. Additionally, there were no differences in adverse events.
The importance of these findings cannot be underscored sufficiently. The development of a biosimilar for treatment in this setting could mean not only lower health-care costs for society overall, but also greater access to an important life-saving or life-extending drug for a larger breast cancer population across the globe.
Rugo and colleagues should be congratulated on the importance of their work. Currently, MYL 1401O is being used in several countries and has been filed with the U.S. Food and Drug Administration for approval in the United States. We look forward to the results of other trastuzumab biosimilars being evaluated, both in the metastatic and early-stage settings.9,10 ■
Disclosure: Dr. Dang reported no potential conflicts of interest.
4. U.S. Food and Drug Administration: FDA approved drug products: Herceptin (trastuzumab). Available at www.fda.org. Accessed February 21, 2017.
5. World Health Organization: WHO model lists of essential medicines (19th edition). Available at www.who.int/medicines/publications/essentialmedicines/en. Accessed February 21, 2017.
7. Mulcahy N: As Herceptin goes off patent, ‘biosimilars’ emerge. Available at www.medscape.com. Accessed February 21, 2017.
8. Rugo HS, Barve A, Waller CF, et al: Effect of a proposed trastuzumab biosimilar compared with trastuzumab on overall response rate in patients with ERBB2 (HER2)–positive metastatic breast cancer: A randomized clinical trial. JAMA 317:37-47, 2017.
9. Pfizer announces positive results from the REFLECTIONS study for potential biosimilar to Herceptin (trastuzumab). Available at www.biosimilarnews.com. Accessed February 21, 2017.
10. Amgen and Allergan announce results from phase 3 study evaluating biosimilar trastuzumab in HER2 positive early breast cancer. Available at www.biosimilarnews.com. Accessed February 21, 2017.
Among women with ERBB2-positive metastatic breast cancer receiving taxanes, the use of a proposed trastuzumab biosimilar compared with trastuzumab resulted in an equivalent overall response rate at 24 weeks.— Hope S. Rugo, MD, and colleagues
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