However, the results of a direct comparison [22] have demonstrated that a radioiodinated dimeric form of the anti-HER2 affibody molecule (ZHER2:4)2 (KD = 3 nM) does not provide higher tumor uptake than its monomeric form ZHER2:4 (KD = 50 nM), despite the appreciably higher affinity of the dimer (Figure 5A). This evidence concerns the gene ERBB2 and neoplasm.