Xenograft and Drug Treatment Models

PC3 Wt (wild type, PSMA negative) and PC3(+) (prostate cancer cell line transfected with human PSMA) were provided by Dr. Hisataka Kobayashi [24]. PC3(+) and PC3 Wt cell suspensions [2 × 10⁶ cells; PBS:Matrigel (70:30)] from in vitro cell culture were subcutaneously implanted (right shoulder) into athymic male mice (FOX/nu, Envigo, 5 weeks old) for use as a positive and negative control respectively for in vitro and in vivo studies. For the PDX models, athymic nude mice (male; FOX/nu, Envigo, 5 weeks old) were subcutaneously implanted (right shoulder) with LuCaP73, LuCaP167, or LuCaP136 tumor cell suspensions [2 × 10⁶ cells; PBS:Matrigel (70:30)] prepared from fresh tumors excised from respective mouse xenografts [21]. When tumors reached the appropriate size (> 100 mg), mice were enrolled in imaging studies or euthanized and tumors excised and fast-frozen for in vitro saturation binding assays to determine PSMA levels (B_max) for each tumor type and K_d of [¹⁸F]DCFPyL (Supplementary information: Materials and methods). All animal studies were performed in accordance with NIH Guidelines for the Care and Use of Laboratory Animals using IACUC-approved protocols.

Tumor-bearing mice (tumors >100 mg) were randomly divided (based on tumor volume) into control and ADT (Firmagon (degarelix), Ferring Pharmaceuticals) treated groups. Treated mice were dosed with degarelix (25 mg/Kg) subcutaneously at baseline (following imaging) and day 14 [25, 26].