Technetium (99mTc) arcitumomab

Arcitumomab is a medicament on the basis of a fragment of a murine monoclonal antibody which is linked to the radioisotope Technetium ( 99m Tc). Arcitumomab is an immunoconjugate, which is used as a diagnostic agent in oncology.

The antibody is a Fab fragment of IMMU -4, a murine IgG1 monoclonal antibody that is derived from the ascites of mice by purification. For this, the belly of water is treated with pepsin to produce from the IMMU -4 F (ab ') 2 fragments and then ultimately the 50 -kDa Arcitumomab.

Arcitumomab was sold under the trademark CEA- Scan Immunomedics; permission for distribution was withdrawn in 2005 by the EMA.

Mechanism of Action

The carcinoembryonic antigen (CEA ) is a protein which is overexpressed in many tumor cells on the surface. In particular, expressing more than 95 % of all colorectal cancers CEA. For such tumors Arcitumomab can be used as an in vivo diagnostic agent to obtain a forecast of the absorption of the drug and the disease process. Combined with a single-photon emission computed tomography ( SPECT), it provides specific high-resolution functional images, which visualize the colon cancer localization, extent of remission and / or metastasis development.

Dosage

The ampoules with Arcitumomab included in the delivery form no technetium. Immediately prior to intravenous administration is eluted with sodium pertechnetate solution from a technetium generator, reconstituted and diluted with physiological saline solution for injection. For adults, a single injection of 1 mg, with 750-1000 MBq 99mTc recommended labeled Fab 'fragment. The radiolabelled solution ( 5-10 ml) should be administered as an intravenous injection over a period of about 30 seconds.

The half-life of 99mTc is 6.02 hours. In the decay gamma rays are generated with 140.5 keV, which are detected and evaluated by SPECT.