F. Hoffman-La Roche Ltd. continued its recent flurry of deal making by shelling out $56.5 million in cash for Therapeutic Human Polyclonals Inc. (THP) and its antibody-producing transgenic rabbits.

The acquisition came just days after Basel, Switzerland-based Roche's diagnostics unit acquired 454 Life Sciences for $154.9 million in cash. Earlier in March, Roche entered drug discovery collaborations with KineMed Inc. and Molecular Partners. The big pharma also did some deal breaking during the month, backing out of drug development deals with Maxygen Inc. for a next-generation Factor VII product and Trimeris Inc. for a next-generation HIV fusion inhibitor. (See BioWorld Today, March 15, 2007, March 19, 2007, and March 30, 2007.)

The THP acquisition serves to bolster Roche's stake in the antibody market, providing a new approach to the creation of next-generation versions of blockbuster monoclonals like Avastin (bevacizumab) and Rituxan (rituximab). THP's rabbit-based technology platform complements Roche's existing antibody partnerships with Genmab A/S for humanized mouse-derived antibodies and with MorphoSys AG for humanized antibodies generated in vitro.

"Roche is very interested in monoclonal antibodies from rabbits," said Wim Van Schooten, cofounder and former CEO of THP. While rabbits and mice are both efficient at producing monoclonals, THP's rabbit system generates antibodies that differ from those produced in mice and may allow stronger binding to certain targets, resulting in enhanced efficacy.

Yet monoclonals are just the tip of the carrot for THP's rabbit-based technology. Its humanized polyclonal antibodies, although still in preclinical, may be able to address some of the shortcomings of monoclonals, Van Schooten said.

"The problem with monoclonals is they are not very potent because they target only one molecule," Van Schooten explained. "This is why people attach a payload to a monoclonal." Additionally, monoclonals targeting complex diseases such as cancer or viruses may become ineffective if their single target mutates during the course of the disease.

Animal-derived polyclonals have been in use for more than a century. Other companies working on human or humanized polyclonals include Symphogen A/S, which is in Phase I with a fully-human recombinant polyclonal produced in vitro, and Kirin Brewery Co. Ltd., which gained a cow-based humanized polyclonal platform through its 2005 acquisition of Hematech LLC. (See BioWorld Today, July 27, 2005.)

As a result of its acquisition by Roche, THP closed its Mountain View, Calif.-based headquarters, where co-founders Van Schooten and Roland Buelow were based. The rest of the company worked out of a research facility in southern Germany, which will remain operational. Employees will be integrated into the nearby Roche Pharma Center of Excellence for Protein Research.

Van Schooten said THP's 2002 collaboration with SangStat Medical Corp., since acquired by Genzyme Corp., will now transfer to Roche. The companies are developing a humanized version of Thymoglobulin (anti-Thymocyte-globulin, rabbit). While the rabbit-derived polyclonal antibody is approved for the treatment of acute renal graft rejection, a humanized version could open the door to use in broader applications. (See BioWorld Today, Nov. 12, 2002.)

Founded in 2000, THP had raised $12.5 million in financing from Research Corporation Technology (RCT) BioVentures and Genzyme Corp. prior to its acquisition. The company also received a $5.8 million grant from the National Institutes of Health to collaborate with SRI International on the development of humanized polyclonal antibodies against Botulinum neurotoxin.