Immunomedics Inc. has published results of a new andimproved agent to bind tumor cells in the current issue of thejournal Cancer.

This second-generation monoclonal antibody (MAb), MN-14,successfully targeted 89 percent of disease sites in 22colorectal cancer patients in the Phase I/II trial, as confirmedby CAT scans.

The Morris Plains, N.J., company (NASDAQ:IMMU) is developingMAbs linked to radioisotopes for detection and treatment ofcancer. The first-generation ImmuRAID-CEA has been underFDA review since April 1991 as a colorectal diagnostic agent.

The new MN-14 appears to have 10 times the affinity ofImmuRAID-CEA for the tumor marker carcinoembryonicantigen. CEA is present in nearly all cases of colorectal cancerand is frequently found in cancers of the pancreas, stomach,lungs and breast.

A therapeutic product incorporating the new antibody is inPhase I/II trials for the treatment of colorectal, breast and lungcancers.

This product candidate has been "humanized" to avoid allergicreactions that may arise from the mouse antibody. Humanizingentails splicing certain components of a mouse antibody to ahuman antibody by recombinant DNA methods, thus reducingthe mouse portions.

The humanized version should be preferable for repeated usein patients, said David Ortlieb, Immunomedics' chief executiveofficer and president. "We are also testing new therapeuticisotopes, such as rhenium-188, that hold promise in thedevelopment of a line of cancer therapeutic agents," he added.

Tagged with a suitable radioisotope, cancer-seeking antibodiessuch as MN-14 are injected into a patient's body, where theytravel to the tumor site and attach to a specific marker such asCEA. Therapeutic isotopes kill tumor cells. Radiation emitted byan imaging isotope, meanwhile, "lights up" the cancer site whenthe patient is scanned by a gamma camera.

Immunomedics holds exclusive rights to a 1989 U.S. patent thatcovers both the new MN-14 antibody and ImmuRAID-CEA.

High CEA levels in the bloodstream of some cancer patients didnot deter the injected MAb conjugate from reaching andbinding to the tumor site, said Hans Hansen, a co-author of theCancer study and vice president of exploratory research atImmunomedics. "The next step," Hansen said, "is to determineif this antibody delivers higher, therapeutic doses of radiationto cancers because of its high binding affinity to CEA ontumors."

-- Nancy Garcia Associate Editor

(c) 1997 American Health Consultants. All rights reserved.

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