The U.S. Food and Drug Administration (FDA) has approved trastuzumab-dttb (Ontruzant®; Samsung Bioepis) a biosimilar referencing* trastuzumab (Herceptin®; Genentech/Roche), for adjuvant treatment of HER2-overexpressing (ER/PR-negative o with high risk**) breast cancer, metastatic breast cancer and metastatic gastric cancer or gastroesophageal junction adenocarcinoma in patients who have not received prior treatment for metastatic disease.
The agent is Samsung Bioepis’ first oncology biosimilar to receive FDA approval, and will be marketed and distributed in the United States (US) by Merck (MDS).
According to media reports, Merck, which hopes to drive long-term growth, has an agreement with Samsung Bioepis for the development and commercialization of several other pre-specified and undisclosed biosimilar candidates.
Biosimilars are not the same as generics. Generally, generic drugs are relatively simple molecules that are easy to characterize and have a small, well-defined structure. In contrast, biosimilars are complex molecules with many post-translational modifications., requiring extensive analysis to establish their structural and functional characterization.
As part of the regulatory approval process, marketed biosimilars have been compared to an FDA-approved biologic, known as the reference product, for the approved indications based on a totality of evidence. Such approval is based on a review of data inclusive of foundational analytical similarity data, nonclinical data, clinical pharmacology, immunogenicity, clinical efficacy and safety data.
Although some differences between the formulation may be acceptable to regulators, overall, these agents are highly similar to a reference product, and, in studies, no clinically meaningful differences in safety and effectiveness, compared to the biological reference product, have been observed. Most (minor) differences in are between clinically inactive components.
According to statements made by the FDA, prescribers and patients should have no concerns about using these medications instead of reference
“For many cancer patients in the US, battling cancer has not only been a health issue, but a considerable financial burden brought on by cancer treatment,” said Sang-Jin Pak, Senior Vice President and Head of Commercial Division, Samsung Bioepis.
“Biosimilars are intended to be lower cost, high-quality treatment options that have the potential to alleviate such burden. We sincerely hope our trastuzumab biosimilar will do exactly that,” Sang-Jin Pak added.
“At Samsung Bioepis, we will continue to demonstrate our enduring commitment to biosimilars by further strengthening our pipeline and widening the availability of approved treatments for cancer patients across the US,” he comcluded.
In November 2017 trastuzumab-dttb was approved by the European Commission (EC). The drug has since been launched in a growing number of European countries.
Other trastuzumab biosimilars
In December 2018 the FDA approved Herzuma® (trastuzumab-pkrb) another biosimilar of trastuzumab previously known as CT-P6, for the treatment of patients with HER2-overexpressing breast cancer. This drug was co-developed by Celltrion and Teva Pharmaceutical Industries.
“Biosimilars are of growing importance to the oncology community and the approval of HERZUMA may provide more patients access to this important therapy,” said Woosung Kee, Chief Executive Officer of Celltrion at the time of approval in December.
“This is …oncology biosimilar approval in the United States … reinforces the goal for all of our approved products, providing broader treatment options for patients and the providers who treat them,” Kee added.
* A reference product (drug) means the single biological product licensed under section 351(a) of the PHS Act against which a biological product is evaluated by the US Food and Drug Administration in a 351(k) application (section 351(i)(4) of the PHS Act)
** High-risk is defined as ER/PR positive with one of the following features: tumor size >2 cm, age <35 years, or tumor grade 2 or 3.
*** Celltrion and Teva Pharmaceutical Industries Ltd. entered into an exclusive partnership in October 2016 to commercialize a trastuzumab biosimilar in the U.S. and Canada.
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