Researchers at ImmunoGen Inc. and the Dana Farber CancerInstitute have published data demonstrating the effectivenessof the company's anti-cancer compounds that are now inclinical trials.

In the Dec. 1 issue of Cancer Research, the scientists showedthat a plant-derived toxin called ricin can be targeted tolymphomas and leukemias. This is done by blocking the part ofricin that normally recognizes most cells, and then adding amonoclonal antibody that will direct the ricin only to cancercells.

The company's blocked ricin, which retains the molecule's Bchain, is more potent than other ricin-based compounds thatlack the B-chain, the scientists said. Others have sought toderail the toxin's non-specific effects on cells by using only thericin A chain. However, this strategy partially handcuffs thetoxin because the B chain appears to help the A chain enter andwork inside cells.

Blocked B-chain ricin linked to various monoclonals are in trialsfor B-cell leukemias and lymphoma, AIDS-related lymphoma,multiple myeloma, and as an adjunct in bone marrowtransplants.

Patents on blocked ricin technology are held by the DanaFarber Institute in Boston, which has licensed the rights to itsuse exclusively to ImmunoGen. Stock of the Cambridge, Mass.,company (NASDAQ:IMGN) closed at $17.25, up $1.

-- Roberta Friedman, Ph.D. Special to BioWorld

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