Biological Evaluation of 99mTc-HYNIC-EDDA/tricine-(Ser)3-D4 Peptide for Tumor Targeting

Background: D4 small peptide (Leu-Ala-Arg-Leu-Leu-Thr) was selected as an appropriate agent for specific targeting of epidermal growth factor receptor (EGFR). Objective: The aim of study was to investigate the ^99mTc-labeled D4 peptide for non-small cell lung tumor targeting. Method: HYNIC-(Ser)3-D4 peptide was labeled with ^99mTc using mixture of tricine and ethylenediamine diacetic acid (EDDA) as co-ligands. The in vitro cellular uptake of radiolabeled peptide was evaluated by blocking test on human non-small cell lung cancer (A-549) cell line and its biodistribution was evaluated in A-549 xenografted nude mice. Results: This conjugated peptide was labeled with 99mTc in high radiochemical purity and it was highly stable in buffer and serum. The un-blocked to blocked cellular radioactivity ratio was 4-fold that showed a specific binding of this radiolabeled peptide on A-549 cell. Animal biodistribution in A-549 xenografted nude mice showed rapid clearance from blood and other non-target organs. Tumor uptake values as %ID/g (percentage of injection dose per gram of tissue) were 2.47% and 1.30% at 1 and 4 h after injection. Conclusion: This study showed the ^99mTc-EDDA/tricine-HYNIC-(Ser)3-D4 peptide had tumor targeting on the non-small cell lung tumor.