Bioevaluation of a novel [ 32 P]‐CP‐PLLA microparticle for pancreatic cancer treatment

A novel [ 32 P]‐CP‐PLLA ([ 32 P]‐chromic phosphate‐poly‐ L ‐lactic acid) microparticle was designed and evaluated for the treatment of pancreatic carcinoma. The microparticle was prepared from [ 32 P] chromic phosphate and poly‐ L ‐lactic acid. Bioelimination, biodistribution, SPECT image, and therapeutic effect were studied in mice bearing human pancreatic tumor xenografts. [ 32 P]chromic phosphate ([ 32 P]‐CP) colloid at the same radioactivity dose was compared as the control. High radioactivity (>95%ID) of [ 32 P]‐CP‐PLLA was retained at the tumor, and almost no radioactivity excretion (<1%ID) was observed in urine and feces for 14 days, while radioactivity of [ 32 P]‐CP colloid, was distributed to the liver, spleen, and lung (varied individual), and the excretion increased over 5%ID. Compared with controls, reduced tumor volumes were seen in the [ 32 P]‐CP‐PLLA microparticle treatment group ( P <0.01). Dose dependence was seen histologically. [ 32 P]‐CP‐PLLA microparticle retained high activity and long‐term residence in tumor. With minimal distribution to normal organs [ 32 P]‐CP‐PLLA microparticle is superior to [ 32 P]‐CP colloid and is more suitable for brachytherapy in solid tumor. Drug Dev Res 71:364–370, 2010. © 2010 Wiley‐Liss, Inc.