PSMA-targeted diabodies were developed from the huJ591 and D2B antibodies (PSMA-targeted huJ591 cysteine-modified scFv diabody labeled with 89Zr, PSMA-targeted cysteine-modified scFv diabody labeled with 99mTc, PSMA-targeted huJ591 DOTA (1,4,7,10-tetraazacyclodode cane-N,N,N,N-tetraacetic acid)-cysteine-modified scFv diabody labeled with 64Cu) and so far their usefulness was evaluated for prostate cancer diagnosis by PET and SPECT [84,88,89]. The gene discussed is FOLH1; the disease is prostate cancer.