Problems associated with radioimmunodetection and possibilities for future solutions.

It is the opinion of the authors that the molecule of the future for radioimmunodetection (and hopefully radioimmunotherapy and delivery of drugs) will have the following characteristics: It will be an altered fragment, rather than an intact molecule or fragment. It will be small, perhaps 60,000 molecular weight, yet remain in the vascular compartment for a comparatively long period of time, then be eliminated via the kidney. It will be of human origin or a murine molecule altered to mask its immunogenic properties. It will be 111In- or 99mTc-labeled or bifunctionally chelated to another metal ion. It will target a cell surface antigen, but one that does not circulate. It will be used in combination with derivatives of other MoAbs that target other antigens on the cell. It would be a hapten-type device that follows the administration of a "bifunctional MoAb." Whatever the final molecule, it will be administered to a patient who has been "prepped" with an antigen-enhancing substance or one that "unmasks" a gene and allows a repressed marker to be expressed by the tumor cell to which the MoAb was developed. It may be a MoAb that attaches to a white cell, which then chemotactically seeks the tumor that has been previously induced to produce a substance that the white cell recognizes.