The news came in the wake of a unanimous vote two months earlier by FDA advisors who recommended approval of Zarxio [1]. It is hoped that this first approval will make further complex biological therapies readily accessible in the US.

The approval of Zarxio was based on review of evidence that included comparative structural and functional characterization, animal studies, human pharmacokinetics and pharmacodynamics, and clinical immunogenicity data, and other clinical safety and effectiveness data, which demonstrate that Zarxio is highly similar to US-licensed Neupogen.

Sandoz, the generics division of Novartis, already markets its biosimilar filgrastim product under the brand name Zarzio in more than 40 countries outside the US [2]. Theirs was the first biological application to be accepted by FDA via its abbreviated biosimilars pathway.

Filgrastim is a granulocyte colony-stimulating factor (G-CSF) used to stimulate bone marrow to produce more neutrophils to fight infection in patients undergoing chemotherapy.

FDA can designate a biosimilar as interchangeable with its reference product thanks to the Biologics Price Competition and Innovation (BPCI) Act, which was passed as part of the Affordable Care Act (Obamacare) that President Obama signed into law in March 2010 [3].

However, Zarxio was approved as a biosimilar, not as an interchangeable product. According to the BPCI Act, only a biological that has been approved as interchangeable may be substituted for the reference product without the intervention of the healthcare provider who prescribed the reference product.

FDA has designated a placeholder non-proprietary name for this product – filgrastim-sndz. The agency makes it clear that provision of a placeholder non-proprietary name should not be viewed as reflective of the agency’s decision on a comprehensive naming policy for biosimilar and other biological products [4]. ‘While the FDA has not yet issued draft guidance on how current and future biological products marketed in the United States should be named, the agency intends to do so in the near future,’ reads a statement from the agency.

The decision to designate a ‘placeholder non-proprietary name’ for the biosimilar has prompted industry groups to call for FDA to promptly issue appropriate guidance on the issue of naming, as well as to issue or finalize guidances on other outstanding issues such as establishing interchangeability. While the US Generic Pharmaceutical Association (GPhA) reiterated its stance that ‘the Agency’s departure from the currently accepted international nonproprietary name (INN) system could disrupt the ability to track and dispense these medicines, risking provider confusion and patient safety.’

It remains to be seen what savings will be made for the patient or the caregiver as a result of this approval, although Sandoz says the biosimilar will be priced competitively. A European cost-efficiency analysis for the three most common G-CSF products used to treat febrile neutropenia: Neupogen and its biosimilar Zarzio and the pegylated form of filgrastim, pegfilgrastim (Neulasta, Amgen), concluded that biosimilar filgrastim was the most cost saving compared to both originator filgrastim and pegfilgrastim [5].

‘Filgrastim has proven clinical value in treating patients at increased risk of neutropenia, but it is underused in the US for a variety of reasons, including price’, said Dr Louis Weiner, Chairman of the Department of Oncology and Director of the Georgetown Lombardi Comprehensive Cancer Center at Georgetown University, Washington DC, USA, quoted in a press release from Sandoz. ‘Biosimilars have the potential to increase access and the approval of Zarxio may reduce costs to the healthcare system. The comprehensive data set supports its use in clinical practice’.

Related article
Filgrastim biosimilar has similar safety and efficacy to Neupogen

References
1.   GaBI Online - Generics and Biosimilars Initiative. FDA advisers recommend approval of filgrastim biosimilar [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 Mar 13]. Available from: www.gabionline.net/Biosimilars/News/FDA-advisers-recommend-approval-of-filgrastim-biosimilar
2.   GaBI Online - Generics and Biosimilars Initiative. FDA accepts biosimilar filgrastim application [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 Mar 13]. Available from: www.gabionline.net/Biosimilars/News/FDA-accepts-biosimilar-filgrastim-application
3.   GaBI Online - Generics and Biosimilars Initiative. Assessment of interchangeability under the BPCI Act [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 Mar 13]. Available from: www.gabionline.net/Biosimilars/Research/Assessment-of-interchangeability-under-the-BPCI-Act
4.   GaBI Online - Generics and Biosimilars Initiative. US senators call for guidance on biosimilars [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 Mar 13]. Available from: www.gabionline.net/Biosimilars/General/US-senators-call-for-guidance-on-biosimilars
5.   GaBI Online - Generics and Biosimilars Initiative. Biosimilar filgrastim provides cost savings for treating febrile neutropenia [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 Mar 13]. Available from: www.gabionline.net/Biosimilars/Research/Biosimilar-filgrastim-provides-cost-savings-for-treating-febrile-neutropenia 

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