131I-BA52 is a small molecule, a melanin-binding benzamide, being developed for the therapy of malignant melanomas. Benzamide derivatives bind to melanin, and their iodinated form exhibits high uptake in melanin-positive melanoma. Melanin is a biopolymer containing indole units and is contained in 75–90% of malignant melanomas. 131I-BA52 is an improvement on 131I-BZA2 and 131I-MIP-1145 (131I-Ioflubenzamide, Solazed®). The results of the first clinical trial with 131I-BA52 were published in January 2014.
In 2013 the drug completed a safety study intended to estimate the ideal dosimetry for the therapy. At the same time, this trial corresponds to the first therapeutic application of 131I-BA52 in patients with metastatic malignant melanoma (average dose was about 100 mCi) who were selected on the basis of imaging made with 123I-BA52 injection (6 mCi). Observed antitumor effects on a very small cohort of benzamide-positive patients demonstrated a surprisingly long survival of more than 2 years. Unfortunately, the development of this drug is presently on hold.