Mini antibodies: biotech's next big thing?

LONDON (Reuters) - GlaxoSmithKline Plc's head of biotech research is excited about a new generation of "slimline" antibody medicines that may be successors to current blockbusters such as Avastin and Rituxan.

That's no surprise, perhaps, given Ian Tomlinson headed the next-generation antibody firm Domantis until Glaxo snapped it up for 230 million pounds ($405 million) in 2006.

But the fact the world's second-largest drugmaker has put the technology centre-stage shows how a coming wave of ultra-small antibody products -- capable of working in ways impossible for conventional treatments -- is gaining attention.

"I think the next generation approaches have tremendous applications across the board," Tomlinson said in an interview. "It's potentially a big deal; the question is how big."

Today's monoclonal antibodies are large proteins that act as footsoldiers for the immune system. They are already the fastest-growing section of the global drugs market, with sales expected to hit $49 billion in 2013 compared with $26 billion in 2007, according to market analysis group Datamonitor.

And by the middle of the next decade, Genentech Inc and Roche AG's cancer drug Avastin is predicted by analysts to be the biggest-selling medicine of any type in the world.

But conventional antibodies, which must be injected, are limited in the parts of the body they can reach.

Next-generation antibody fragments, which are a fraction of the size, are potentially more flexible, cheaper to make and could lead to the development of drugs that are inhaled, used as eyedrops or given by mouth.

Last week, Belgium's Ablynx NV, which produces so-called nanobodies derived from llama antibodies, signed its most lucrative deal to date with Germany's Merck KGaA.

It was the latest in a string of alliances with Big Pharma players, including Novartis AG, Wyeth and Boehringer Ingelheim.

DEALMAKING

Other major drugmakers are pursuing rival approaches.

A year ago, Bristol-Myers Squibb Co bought Adnexus Therapeutics for $430 million to get access to its novel class of drugs called Adnectins, which have similar properties to monoclonal antibodies but are much smaller.

And in 2006, Amgen Inc bought Avidia in a $290 million deal to exploit its Avimer platform technology.

At the same time, a host of independent biotech companies are developing different technologies to shrink tomorrow's antibody drugs -- among them Switzerland's ESBATech, U.S.-based Trubion Pharmaceuticals Inc and Denmark's Genmab.

At the moment, the jury is out on how well the new generation of products will work, since even the most advanced are only now starting mid-stage Phase II clinical trials.

"The answer is only going to come when we get the clinical data for these things in the next two years or so," said Sam Fazeli, a biotech analyst at brokerage Piper Jaffray.

Nonetheless, Ablynx CEO Edwin Moses is convinced the ability of these smaller molecules to penetrate tissue more effectively will open many new doors in treatment.

"There will be areas where we can only do as well as a whole antibody but there are certainly areas where we feel we can do better," he said.

Others are more wary. Genmab CEO Lisa Drakeman, whose company is developing next-generation mini antibodies called Unibodies as an adjunct to its main business in conventional ones, sees the emerging technology as more of a niche.

"My personal feeling is that whole antibodies is where most of the products will come from. We think next generation technology will be for special applications," she said.

Glaxo, which was slow to get into antibody treatments in the first place, is hedging its bets by backing both the established and new approaches.

"The current market for monoclonal antibodies is very big and is growing rapidly -- GSK is aggressively pursuing both avenues," Tomlinson said.

(Editing by David Holmes)