Novartis’ generic medicines subsidiary Sandoz has made a significant investment in the development of biosimilar versions of established biologic drugs via a $263 million investment in US firm Momenta Pharmaceuticals.

In addition to biosimilars, the agreement also covers complex generics, medicines that like biosimilars are hard to develop because of difficulties in proving that a copycat version has the same characteristics as the branded product.

Sandoz and Momenta have already been working together on the development of a generic version of Sanofi-Aventis’ Lovenox (enoxaparin), used for deep vein thrombosis and other cardiovascular indications, which was submitted in the USA last August. In addition to extending this alliance to include European development of this drug, the new deal will be expanded to include four other unnamed biologic and complex drugs.

In the USA, there is still no defined regulatory route to approval for these products, mainly because it is not possible to make a biologic by one production process that is completely identical to another using a different process. This means that classical notions of bioequivalence - which underpin the generic drug market - do not apply, so regulators have to draw up special criteria to support approval of follow-on biologics.

The US Food and Drug Administration has still not done so, although the European Commission completed its regulatory framework earlier this year and has already approved the first two biosimilars for sale.

Sandoz has been a pioneer in the development of biosimilars, known in the USA as follow-on biologics, and won approval on both sides of the Atlantic for Omnitrope, a human growth hormone product that is a copy of Pfizer’s Genotropin (somatropin) product.

But while classed as a biosimilar in Europe, the US approval made use of an existing regulatory loophole which only makes it possible for the FDA to approve small, simple follow-on biologics.

Underpinning the collaboration is Momenta’s characterisation technology, which enables the detailed sequencing and analysis of complex mixtures and, it is hoped, could provide data that will satisfy regulators that Sandoz’ copycat products are substitutable for the original brand.

A key element in the technology is its ability to measure sugar side chains on protein drugs – the glycosylation pattern that can have an impact on its efficacy, bioavailability and safety.

Sandoz does not identify the biosimilars it is developing for commercial reasons, but other first-generation biologics that have lost patent protection include interferon alfa, insulin, erythropoietin and colony stimulating factors. Datamonitor has estimated that biologics with annual sales of around $20 billion are out of patent and vulnerable to generic competition.