RESUMO
Recent cancer therapies have focused on reducing immune suppression in the tumor microenvironment to prevent cancer progression and metastasis. PD-1 is a checkpoint protein that stops the immune response and is expressed on immune T cells. Cancer cells express a PD-1 ligand (PD-L1) to bind to the T-cell surface and activate immunosuppressive pathways. This study aimed to design, synthesize, and evaluate a 99mTc-labeled PD-L1-targeting cyclic peptide inhibitor (99mTc-iPD-L1) as a novel SPECT radiopharmaceutical for PD-L1 expression imaging. AutoDock software (version 1.5) was used to perform molecular docking for affinity calculations. The chemical synthesis was based on the coupling reaction of 6-hydrazinylpyridine-3-carboxylic acid with a 14-amino-acid cyclic peptide. iPD-L1 was prepared for 99mTc labeling. Radio-HPLC was used to verify radiochemical purity. The stability of the radiopeptide in human serum was evaluated by HPLC. iPD-L1 specificity was assessed by SDS-PAGE. [99mTc]Tc-iPD-L1 cellular uptake in PD-L1-positive cancer cells (HCC827 and HCT116) and biodistribution in mice with induced tumors were also performed. One patient with advanced plantar malignant melanoma received [99mTc]Tc-iPD-L1. The iPD-L1 ligand (AutoDock affinity: -6.7 kcal/mol), characterized by UPLC mass, FT-IR, and UV-Vis spectroscopy, was obtained with a chemical purity of 97%. The [99mTc]Tc-iPD-L1 was prepared with a radiochemical purity of >90%. In vitro and in vivo analyses demonstrated [99mTc]Tc-iPD-L1 stability (>90% at 24 h) in human serum, specific recognition for PD-L1, high uptake by the tumor (6.98 ± 0.89% ID/g at 1 h), and rapid hepatobiliary and kidney elimination. [99mTc]Tc-iPD-L1 successfully detected PD-L1-positive lesions in a patient with plantar malignant melanoma. The results obtained in this study warrant further dosimetric and clinical studies to determine the sensitivity and specificity of [99mTc]Tc-iPD-L1/SPECT for PD-L1 expression imaging.
RESUMO
PURPOSE: To determine in vitro, the efficacy and safety window of not-front-line and first-line anti-colorectal (CRC) drug combinations. METHODS: The adenocarcinoma cell line Colo 320DM and normal human mesenchymal stem cells derived from adipose tissue were used respectively to determine the anti-CRC efficacy (% of Colo 320DM cell death [CD]) and safety window [SW] - % Colo 320DM percent cancer death (PCD)/% of mesenchymal stem cell's death) of drug combinations, using the adenosine triphosphate-based chemotherapy response assay (ATP-CRA). RESULTS: First-line anti-CRC drug combinations (5-fluorouracil [5FU]/oxaliplatin [oxa] and 5-FU/Oxa /leucovorin [Leuco]) produced 57.7% and 52.4% CD, and 1.38 and 2.44 SW, respectively. Combinations of 5-FU/Oxa and 1 to 3 non-front line drugs led to 56.3-99.8% CD and to 0.96-2.2 SW. The highest safety window corresponded to 5FU/Oxa/ carboplatin [Carbo] (93% CD and 1.4 SW) and to 5-FU/ Oxa/cisplatin [Cispl] (93.5% CD and 1.4 SW). In contrast, non-front line drugs led to 89.8-97.4% CD and to 1.1-78.2 SW. Outstandingly, those combinations containing Carbo/ Cispl/3,3'-diindolylmethane (DIM), aspirin (Asp), or 3,3'- DIM/ Asp showed a very high CD (91.9-96.9% [39.2-39.5 times higher than first-line-combined drugs]) and very wide SW (57.8-81.56 [66.6-40 times higher than the first-line drug combinations]). CONCLUSIONS: Human mesenchymal stem cells could be an excellent alternative to laboratory animals, when testing the safety profiles of drugs. The most promising combinations of non-frontline drugs to treat CRC are Carbo/Cispl/ Asp and Carbo/Cispl/DIM.
