Studies on biodistribution and imaging of 188Re labeled insulin-like growth factor-1 analogue in nude mice bearing human pancreatic carcinoma

Objective To evaluate the biodistribution and planar gamma camera imaging charact- eristics of 188Re labeled insulin-like growth factor 1 analogue QSSRe-IGF-1A）in tumor-bearing mice. Methods （1）To label IGF-1A with raRe directly and to determine the labeling efficiency. （2）To establish nude mice model which bearing human pancreatic carcinoma cell Patu8988. （3）To scan those nude mice at 15 min, 1 h, 4 h, 24 h, 3 d and 5 d after intratumor injection with 188Re-IGF-1A into their tumors. （4）To scan those nude mice at 15 min, 1 h, 2 h, 4 h and 24 h after intratumor injection with 188ReO4- into their tumors. To calculate the tumor to normal tissue ratio （T/NT） and the percentages of injected dose per gram tissue（%ID/g） of different organs. Results （1）The labeling efficiency of 188Re-IGF-1A was （94.07 ±0.32） %. （2）The largest uptake of tumors was （42.38±17.82） %ID/g at 4 h after injection of lSSRe-IGF-1A. Then the tumor to normal tissue ratios increased and the largest tumor to muscle ratio was 6531.79±4930.26 at 5 d after injection. （3）188ReO4- was major distributed in thyroid glands, stomachs, tumors and blood in nude mice after injection at first. Then %ID/g decreased rapidly in tumors. （4）The difference of %ID/g was significant （t=5.877, t= 13.287, P〈0.01） in tumors and kidneys between 188Re-IGF-1A group than in 188ReO4- group. The largest ratio of tumors in the two groups was 74.10 at 24 h after injection. （5）After being injected, 188Re-IGF-1A formed clear images in tumors, 5 d later, nothing but tumors can be seen. Conclusions 188Re -IGF-1A has good affinity with human pancreatic cancer, and the tumor to muscle ratios in nude mice is high. So 188Re-IGF-1A is expected to be used for targeting therapy of human pancreatic carcinoma. Key words: Rhenium;  Insulin-like growth factor-1 receptor;  Pancreatic neoplasms;  Mice, nude