Preliminary data from the phase III Heritage trial suggest that a biosimilar to trastuzumab, MYL-14010, is just as safe and effective as its brand-name equivalent for women with HER2-positive advanced breast cancer. The findings, presented during the annual meeting of the American Society of Clinical Oncology in June, may pave the way for the first FDA-approved biosimilar for cancer.

A trastuzumab (Herceptin; Genentech) biosimilar is as safe and effective as its brand-name counterpart for women with HER2-positive advanced breast cancer, according to data presented during the annual meeting of the American Society of Clinical Oncology in Chicago, IL, June 3–7. The findings pave the way for the first FDA approval of a biosimilar for cancer.

In the international Heritage trial, 500 patients with metastatic HER2-positive breast cancer were randomized to receive taxane chemotherapy (docetaxel or paclitaxel) with either the biosimilar MYL-14010 (Mylan) or trastuzumab every 3 weeks for 24 weeks, followed by trastuzumab alone until disease progression.

Women treated with MYL-14010 had a 69.6% objective response rate'the primary endpoint—compared with 64% among women in the trastuzumab arm. The rates of serious adverse events were comparable at 36% (trastuzumab) and 38% (MYL-14010), with neutropenia being the most common.

If approved, the biosimilar could offer a lower-cost alternative to trastuzumab, which has been the cornerstone of therapy for HER2-positive breast cancer, said the study's lead investigator, Hope Rugo, MD, professor of medicine at the University of California, San Francisco, who presented the findings. Investigators will evaluate progression-free survival after participants have completed therapy with trastuzumab alone, she added.

Mylan has already received approval to market MYL-14010 in India, where it is branded as Hertraz. The FDA will consider data both from its use in that country and from the Heritage trial when evaluating the drug's safety and efficacy, said Rugo.

Several other companies—including Pfizer and Amgen—are working on their own versions of trastuzumab, which loses U.S. patent protection in 2019. In addition, ongoing trials are exploring biosimilars of other commonly used cancer drugs, such as rituximab (Rituxan; Genentech) and bevacizumab (Avastin; Genentech).

Thus far, the FDA has approved only one biosimilar: Sandoz's Zarxio (filgrastim-sndz), a biosimilar for Amgen's Neupogen (filgrastim), used to treat neutropenia.

With patent protection on Genentech's blockbuster drug trastuzumab (Herceptin) set to expire in the United States in 2019, several companies, including Mylan Pharmaceuticals, are developing their own versions of the biologic.

With patent protection on Genentech's blockbuster drug trastuzumab (Herceptin) set to expire in the United States in 2019, several companies, including Mylan Pharmaceuticals, are developing their own versions of the biologic.

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In contrast to generic drugs, biosimilars are not exactly identical to their corresponding brand-name counterparts. Whereas generic drugs are copies of small-molecule drugs with relatively simple chemical compositions, biosimilars correspond to complex large-molecule biologics and must be synthesized from living organisms.

Because biosimilars are impossible to precisely replicate, the FDA requires manufacturers to perform extensive analyses and conduct confirmatory clinical studies demonstrating that the products are highly similar to their branded counterparts, without any clinically meaningful differences.

“This is one of the first trials with biosimilars in oncology to demonstrate similar efficacy, safety, and immunogenicity against the reference product,” said Rugo. –Janet Colwell

For more news on cancer research, visit Cancer Discovery online at http://cancerdiscovery.aacrjournals.org/content/early/by/section.