Biosimilars
While the advent of approved biosimilar products remains a future prospect in the US, European regulators brought three such products to market in 2013. This brings the total number of biosimilars approved thus far in Europe to 19. This total, however, represents a comparatively more modest 10 genuinely different products, as several are marketed under two or more trade names, but with each possessing its own marketing authorization.
While Grastofil (Table I) joins a stable of several biosimilar filgrastims already on the market, the other two products represent first-in-class biosimilar approvals. Ovaleap (Teva Pharmaceuticals) is the first biosimilar follicle stimulating hormone (FSH) to be approved; it will compete with two FSH products already marketed in Europe (Merck-Serono’s Gonal-f and Organon’s Puregon).
Hospira’s Inflectra (also approved under a separate marketing authorization as Remsima) is even more interesting in that it represents the first ever biosimilar mAb to gain approval in Europe. It is a biosimilar version of Remicade, which has been on the market in Europe since 1999 and is used to treat a wide range of inflammatory conditions. Remicade generated annual global revenues in the region of $7.5 billion in 2012.
Engineered antibodies
Genentech’s Gazyva represents another milestone in antibody approvals, being the first glycoengineered mAb to come on the market in the US. mAbs are glycoproteins, carrying an oligosaccharide side chain attached to asparagine residue 297 of the antibody’s heavy chains. This glycocomponent plays a central role in triggering antibody-dependant cellular cytoxicity (ADCC), which appears to be the principle mechanism by which antibodies trigger the destruction of cancer cells. This glycocomponent normally contains a fucose sugar residue and removal of the fucose enhances antibody ADCC activity by up to 100 fold. Gazyva’s glycocomponent is enriched in non-fucosylated oligosaccharide variants.
Like Genentech’s already well-established product Rituxan (rituximab), Gazyva targets the CD20 surface protein associated with B lymphocytes and is approved to treat chronic lymphocytic leukaemia, one of Rituxan’s main indications. However, head-to-head clinical trials showed it more effective than Rituxan (5). In addition to the technical innovation, Gazyva will presumably also help Genentech stave off inevitable competition from Rituxan-based biosimilars, now that the latter is coming off patent.
Although a first for the US, a glycoengineered, non-fucosylated mAb (Mogamulizumab; used for the treatment of T cell leukemia-lymphoma) has been on the Japanese market since 2012.
Kadcyla represents a second engineered variant of an already approved mAb to come to market in 2012. This drug is Herceptin to which a small cytotoxic molecule (DM1) has been conjugated, and like Herceptin, it is approved for the treatment of HER2-positive metastatic breast cancer. As in the case of Gazyva-Rituxan, Kadcyla’s approval may prove convenient for Genentech in terms of staving off inevitable future biosimilar competition, now that Herceptin is also coming off patent.
A new insulin analogue
Insulin degludec (Novo Nordisk), a new long-acting insulin also made it to market in Europe in 2013, where it is marketed on its own (tradename Tresiba) and as a co-formulation (tradename Ryzodeg) with a well-known rapid acting insulin analogue, insulin aspart. Interestingly, FDA declined to approve the product last year, seeking additional cardiovascular outcome data.
Insulin degludec differs from native human insulin in that the threonine reside at position B30 has been omitted, and more importantly, from a pharmacokinetic point of view, a hexadecanedioic acid has been attached to lysine B29, via a glutamic acid spacer. As a result, the analogue forms multihexameric structures in subcutaneous tissue. Entry into circulation is dependent upon their slow disassociation, in practice conferring duration of action of 42 hours or more on the product, several hours longer that previously approved engineered long acting insulins.
Download the table of 2013 drug approvals.
References
1.G. Walsh, Biopharm Int. 26 (4) 54-56 (2013).
2.G. Walsh, Biopharm Int.25 (6), 34-36 (2012).
3.G. Walsh,Biopharm Int. 23 (10), 30-41 (2010).
4.G. Walsh, Biopharm Int. 22 (10) 68-77 (2009).
5.V. Goede, K. et al., New England Journal of Medicine, 370, 1101-1110 (2014).