Because the NpG group is a valuable labeling moiety for all radiohalogen elements, radiohalogen-labeled amino acid derivatives ([211At]At-NpGT, [125I]I-NpGT, and [18F]F-NpGT; Fig. 1) were synthesized and characterized for their LAT1-specific cellular uptake and biodistribution in tumor-bearing mice. Here, SLC7A5 is linked to neoplasm.