In vivo testing of ¹⁷⁷Lu-labelled anti-PSMA antibody as a new radioimmunotherapeutic agent against prostate cancer

Aim: The goal of the present study was to test the ¹⁷⁷Lu- labelled anti-PSMA monoclonal antibody 3/F11 (¹⁷⁷Lu-DOTA-3/F11) as a new radioimmunotherapeutic agent in a prostate cancer SCID mouse xenograft model. Materials and Methods: The mAb 3/FU was ¹⁷⁷Lu labelled using 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) as chelating agent. DOTA-3/F11 was tested for cell binding and serum immunoreactivity by flow cytometry. The biodistribution and the therapeutic efficacy of ¹⁷⁷Lu-DOTA-3/F11 in mice bearing PSMA-positive C4-2 prostate cancer xenografts were evaluated. Results: 3/F11 and DOTA-3/F11 showed high and specific cell binding and similar serum half-lives of approximately seven days. Biodistribution studies revealed an increasing tumour uptake of ¹⁷⁷Lu DOTA-3/F11 over time with maximum tumour-to-muscle and tumour-to-blood ratios after 72 h. A single dose of 1 MBq ¹⁷⁷Lu-DOTA-3/F11 inhibited tumour growth and prolonged survival. Conclusion: This study indicated that ¹⁷⁷Lu-DOTA-3/F11 may be a suitable radioimmunotherapeutic agent for the treatment of prostate cancer.