Preclinical evaluation of an 131I-labeled benzamide for targeted radiotherapy of metastatic melanoma

Joyal, John L and Barrett, John A. and Marquis, John C and Chen, Jianqing and Hillier, Shawn M and Maresca, Kevin P and Boyd, Marie and Gage, Kenneth and Nimmagadda, Sridhar and Kronauge, James F and Friebe, Matthias and Dinkelborg, Ludger and Stubbs, James B and Stabin, Michael G and Mairs, Rob and Pomper, Martin G and Babich, John W (2010) Preclinical evaluation of an 131I-labeled benzamide for targeted radiotherapy of metastatic melanoma. Cancer Research, 70 (10). pp. 4045-4053. (https://doi.org/10.1158/0008-5472.CAN-09-4414)

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Abstract

Radiolabeled benzamides are attractive candidates for targeted radiotherapy of metastatic melanoma as they bind melanin and exhibit high tumor uptake and retention. One such benzamide, N-(2-diethylamino-ethyl)-4-(4-fluoro-benzamido)-5-iodo-2-methoxy-benzamide (MIP-1145), was evaluated for its ability to distinguish melanin-expressing from amelanotic human melanoma cells, and to specifically localize to melanin-containing tumor xenografts. The binding of [(131)I]MIP-1145 to melanoma cells in vitro was melanin dependent, increased over time, and insensitive to mild acid treatment, indicating that it was retained within cells. Cold carrier MIP-1145 did not reduce the binding, consistent with the high capacity of melanin binding of benzamides. In human melanoma xenografts, [(131)I]MIP-1145 exhibited diffuse tissue distribution and washout from all tissues except melanin-expressing tumors. Tumor uptake of 8.82% injected dose per gram (ID/g) was seen at 4 hours postinjection and remained at 5.91% ID/g at 24 hours, with tumor/blood ratios of 25.2 and 197, respectively. Single photon emission computed tomography imaging was consistent with tissue distribution results. The administration of [(131)I]MIP-1145 at 25 MBq or 2.5 GBq/m(2) in single or multiple doses significantly reduced SK-MEL-3 tumor growth, with multiple doses resulting in tumor regression and a durable response for over 125 days. To estimate human dosimetry, gamma camera imaging and pharmacokinetic analysis was performed in cynomolgus monkeys. The melanin-specific binding of [(131)I]MIP-1145 combined with prolonged tumor retention, the ability to significantly inhibit tumor growth, and acceptable projected human dosimetry suggest that it may be effective as a radiotherapeutic pharmaceutical for treating patients with metastatic malignant melanoma.

ORCID iDs

Joyal, John L, Barrett, John A., Marquis, John C, Chen, Jianqing, Hillier, Shawn M, Maresca, Kevin P, Boyd, Marie ORCID logoORCID: https://orcid.org/0000-0003-4120-2218, Gage, Kenneth, Nimmagadda, Sridhar, Kronauge, James F, Friebe, Matthias, Dinkelborg, Ludger, Stubbs, James B, Stabin, Michael G, Mairs, Rob, Pomper, Martin G and Babich, John W;
CORE (COnnecting REpositories)