GRPR and neoplasm: Co-injection of a 100-fold molar excess of unlabeled NOTA-PEG2-RM26 significantly (p < 0.0001) reduced tumor and pancreas activity uptake of [177Lu]Lu-PKB2 and [177Lu]Lu-PKB3 and at 2 h pi, confirming the GRPR specificity of both peptides (Table S2 and S3).