Antibodies: They're Not Just for Fighting Infection Anymore

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Therapeutic antibodies have continued to evolve since the first, OKT3, was approved back in 1986. Biotech investors had better pay attention, lest the technology passes them by.

The drugs are similar to the antibodies used by your immune system to fight off bacteria and viruses, but instead of binding to foreign invaders, therapeutic antibodies are designed to bind to human proteins, which inhibit the latter's function. Blocking a protein that promotes the growth of a tumor, for instance, can help slow the progression of the disease.

Most of the therapeutic antibodies have been designed to treat cancer -- Roche's Avastin and Herceptin, for example -- and autoimmune diseases such as Abbott Labs' (NYS: ABT) Humira and Johnson & Johnson's (NYS: JNJ) Remicade. There are also a handful of other indications where antibodies have proven successful, like Biogen Idec (NAS: BIIB) and Elan's (NYS: ELN) multiple sclerosis treatment Tysabri.

Need for speed
If privately held Adimab's technology works, we could see a lot more antibodies on the market. The company's yeast-based discovery technology allows researchers to optimize a therapeutic antibody much quicker than the conventional approaches.

Plenty of drugmakers seem convinced that the biotech's technology will work. Nine different partners have signed on to have Adimab help develop antibodies for them including Biogen Idec and Novo Nordisk.

The next generation
Taking therapeutic antibodies a step further, Seattle Genetics (NAS: SGEN) and ImmunoGen (NAS: IMGN) have developed antibody-drug conjugates that attach a toxic payload to an antibody. The antibody hones the drug into the tumor cells where the toxic payload is delivered to kill the cancerous cell.

Seattle Genetics' first drug using this technology, Adcetris, was recently approved by the FDA, giving credence to the technology. ImmunoGen's lead molecule, T-DM1, is partnered with Roche and should head in front of U.S. and EU regulators in the middle of next year. The phase 2 data was pretty remarkable, although apparently not remarkable enough to justify an accelerated approval from the FDA.

A toxic payload is the most obvious use for antibody-drug conjugates, but the technology could also be used to deliver a therapeutic drug directly to the type of cells that should get it. Using the antibody as a honing device could avoid the side effects caused by some drugs because the drug would be concentrated at the place where it's needed rather than floating around in the bloodstream doing who knows what else.

Multiple targets
The structure of an antibody is like a Y, where the two prongs of the Y are each capable of binding to the target. Researchers figure if one target is good, two must be better, leading companies to develop so-called bispecific antibodies that can bind to two different proteins at the same time. The most obvious application is to use one side to bind to a tumor cell and the other to hone the immune system to the tumor.

This week, Merck (NYS: MRK) enlisted the help of Zymeworks to develop bispecific antibodies. What exactly each half of the bispecific antibodies will attack wasn't disclosed, but we do know Merck is willing to shell out an undisclosed upfront payment and development milestone payments worth as much as $187 million if the drugs actually work.

Old is new again
A few years ago, there was a lot of talk about RNAi -- another way to inhibit a protein's function -- replacing therapeutic antibodies. But RNAi has been slow to develop, and a few large companies have abandoned the field, while therapeutic antibodies have continued to flourish.

Keep your eyes on the technology, Fools; therapeutic antibodies seem to have plenty of life left in them.

At the time this article was published Fool contributor Brian Orelli holds no position in any company mentioned. Click here to see his holdings and a short bio. The Motley Fool owns shares of Johnson & Johnson and Abbott Laboratories. Motley Fool newsletter services have recommended buying shares of Abbott Laboratories, Johnson & Johnson, Elan, and Immunogen, as well as creating a diagonal call position in Johnson & Johnson. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.

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