Boron Neutron Capture Therapy (BNCT) for treatment of cancer has entered Phase I & II clinical trials. Polyhedral boron hydrides figure predominantly in the ongoing trials. Many polyhedral borane and carboranyl derivatives of biomolecules such as amino acids, nucleotides, nucleic acids, porphyrins, antibodies, etc. have been prepared as possible next generation BNCT agents. Such derivatives are usually based upon B-10 or B-12 cages. A convenient synthesis of a novel [B22H22]2- polyhedral cage from NaBH4 (or B-10 enriched NaBH4) has been discovered. Structurally it may be considered a hybrid of decaborane (B10H14) and the [B12H12]2- cage, the two principal starting materials for many BNCT agents. The specific aim of Phase I is to prepare a carboranyl derivative of the [B22H22]2- cage. Substitution of a carboranyl derivative of [B22H22]2- for the usual B10 or B12 cage would immediately make possible biomolecules for BNCT with a two-fold increase in boron content. Another application for [B22H22]2- would be its attachment to DNA or peptide probes for use in a new patented diagnostic technique
