HPMA copolymer-cyclic RGD conjugates for tumor targeting.

This review describes the design and development of N-(2-hydroxypropyl)-methacrylamide (HPMA) copolymer-cyclic RGD conjugates for targeting tumor angiogenesis. Relative to non-targetable systems, HPMA copolymer-RGD4C and -RGDfK conjugates have shown increased tumor accumulation in a variety of solid tumors including prostate, lung, and breast tumor xenografts. Compared to free peptides, copolymers had increased tumor accumulation and decreased uptake in non-target organs such as the liver and spleen. Clinically relevant imaging agents such as (99m)Tc, (111)In, and Gd enabled in vivo imaging of the constructs by scintigraphy and magnetic resonance techniques. Targeted delivery of (90)Y, a radiotherapeutic agent by HPMA copolymer-RGD4C conjugates resulted in tumor size reduction in mice bearing prostate tumor xenografts. Delivery of the geldanamycin derivative 17-(6-aminohexylamino)-17-demethoxygeldanamycin by HPMA copolymer-RGDfK conjugates resulted in increased tumor concentration of the free drug in a prostate xenograft model. These constructs show promise for targeted delivery of therapeutics and imaging agents to solid tumors.