By Randall Osborne

In a deal worth up to $36 million for BioTransplant Inc., the company has signed an extension of its pact with Novartis A.G., adding BioTransplant's mixed bone-marrow chimerism approach to the partnership's ongoing study of how to create tolerance in xenotransplantation.

Elliot Lebowitz, president and CEO of BioTransplant, said the existing collaboration on gene-therapy approaches to tolerance of human immune systems to animal transplants was begun in 1991 and "has been modified a few times." Lebowitz declined to be more specific about the monetary terms of the new deal.

BioTransplant, of Charlestown, Mass., will collaborate with Basel, Switzerland-based Novartis for three years. The mixed bone-marrow chimerism approach uses transplanted porcine bone marrow to "re-educate" the primate recipient system, so it recognizes and does not reject donor tissues. This eliminates the need for chronic immune suppression, which carries a number of drawbacks and dangers.

"A new system is created [using mixed bone marrow chimerism] that recognizes both recipient and donor," Lebowitz said. "That's our platform technology." Other xenotransplant firms have experimented with transgenic pigs, which are genetically engineered with human genes to block rejection of animal organs. BioTransplant's differing strategy is based on research by David Sachs, an immunologist at Massachusetts General Hospital, in Boston, who chairs BioTransplant's scientific advisory board. (See BioWorld Today, Sept. 15, 1997, p. 1.)

Lebowitz said the widened agreement with Novartis will help establish the validity of the mixed bone-marrow approach. "We're hoping that, by collaborating with them technologically, we'll be able to complete our proof-of-principle studies," he said. "We're pretty far along, but it would be hard to predict an exact date" when the study might be completed, he added.

BioTransplant, which went public in May 1996, has collaborated with others, including MedImmune, of Gaithersburg, Md., and Sandoz Ltd., of Basel, Switzerland. The MedImmune deal, worth up to $16 million, is to develop drugs preventing transplant rejection. MedImmune has a Medi-500 antibody that suppresses most T cells. BioTransplant's antibody, BTI-322, is more selective.

Sandoz (which merged with Ciba-Geigy Ltd., also of Basel, to form Novartis A.G.) collaborated with BioTransplant to study the possibility of organ transplants from pigs to humans. BioTransplant's XenoMune system is intended to allow the eventual transplanting of organs to humans from the company's proprietary "mini-swine."

As of June 30, BioTransplant had $33.697 in cash and equivalents. The company's stock (NASDAQ:BTRN) closed Tuesday at $6.50, up $0.25. *

No Comments