With $2.6bn ($2.1bn) in sales, of which $1.6bn were in the US, Lovenox, an injectable drug for the prevention of deep vein thrombosis, is Sanofi-Aventis's top selling drug, so the French company is eager to protect its patent, which expires in the US in 2012.
Teva and Amphastar challenged Lovenox's patent in court, claiming it is unenforceable, but in the latest legal twist this week an appeals court sent the case back to trial, reversing a lower court decision that had invalidated the patent protecting the drug.
However, Momenta has used its sugar-based technology to also produce a generic version of Lovenox called M-Enoxaparin and has an agreement with Sandoz, a division of Novartis, to jointly develop, manufacture, and commercialise the product.
"We have to see what comes out of this now that the case has been returned to the lower court," Sandoz spokesman Kurt Leidner told In-PharmaTechnologist.com.
"We are not going to comment on what our legal strategy for M-Enoxaparin is or the implications of this case for us."
To date the US Food and Drug Administration (FDA) has not approved a generic version of the drug, still Momenta believes it can demonstrate M-Enoxaparin has the same active ingredient as the branded version, despite its complex structure, and has filed an abbreviated new drug application (ANDA).
Lovenox is a low molecular weight heparin, a polysaccharide made up of sugar chains of varying length and sequences, so its precise identification, isolation and characterisation is far from straightforward.
Nonetheless, Momenta claims its technology can rapidly sequence complex sugars in a matter of minutes to hours, allowing detailed descriptions of various heparin products.
Crucially, apart from the production of generic heparins, Momenta's analytical and sequencing techniques can determine how the manufacturing process changes the distribution of sugars present on a protein, thus manipulating its biological properties.
Altering the complex sugar coat of a protein for example can potentially improve efficacy and tissue targeting, reduce negative side effects, such as allergic reactions, and modify the dosing frequency of protein drugs.
Since nine out of the top ten protein-based drugs currently contain sugars, the potential for new improved formulations is huge.
Also attractive is the prospect of applying Momenta's sugar technology in drug delivery through mucosal membranes which are present in the body in areas such as the lungs and gastrointestinal tract.
Although most therapeutic proteins can only be introduced into the body through injection, sugars can efficiently transport these drugs across membranes and facilitate their non-invasive delivery.
Moreover, this method of delivery yields higher levels of bioavailability and can be applied to a variety of marketed drugs and drug candidates.
Momenta is currently focusing on the pulmonary delivery of therapeutic proteins where achieving adequate bioavailability has been a challenge, with specific emphasis on interferon beta, erythropoietin, insulin and human growth hormone.
But whether the company's pioneering technology will take off is dependent on the success of M-Enoxaparin and any legal challenges that may come its way from Sanofi-Aventis.