{"doi":"10.3390/ijms21228860","title":"Radiolabeled 6-(2, 3-Dichlorophenyl)-N4-methylpyrimidine-2, 4-diamine (TH287): A Potential Radiotracer for Measuring and Imaging MTH1","abstract":"MTH1 (MutT homolog 1) or NUDT1 (Nudix Hydrolase 1), also known as oxidized purine nucleoside triphosphatase, has potential as a biomarker for monitoring cancer progression and quantifying target engagement for relevant therapies. In this study, we validate one MTH1 inhibitor TH287 as a PET MTH1 radiotracer. TH287 was radiolabeled with tritium and the binding of [3H]TH287 to MTH1 was evaluated in live glioblastoma cells (U251MG) through saturation and competitive binding assays, together with in vitro enzymatic assays. Furthermore, TH287 was radiolabeled with carbon-11 for in vivo microPET studies. Saturation binding assays show that [3H]TH287 has a dissociation constant (Kd) of 1.97 ± 0.18 nM, Bmax of 2676 ± 122 fmol/mg protein for U251MG cells, and nH of 0.98 ± 0.02. Competitive binding assays show that TH287 (Ki: 3.04 ± 0.14 nM) has a higher affinity for MTH1 in U251MG cells compared to another well studied MTH1 inhibitor: (S)-crizotinib (Ki: 153.90 ± 20.48 nM). In vitro enzymatic assays show that TH287 has an IC50 of 2.2 nM in inhibiting MTH1 hydrolase activity and a Ki of 1.3 nM from kinetics assays, these results are consistent with our radioligand binding assays. Furthermore, MicroPET imaging shows that [11C]TH287 gets into the brain with rapid clearance from the brain, kidney, and heart. The results presented here indicate that radiolabeled TH287 has favorable properties to be a useful tool for measuring MTH1 in vitro and for further evaluation for in vivo PET imaging MTH1 of brain tumors and other central nervous system disorders.","journal":"International Journal of Molecular Sciences","year":2020,"id":74893,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":6,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9619,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":391203,"name":"Sadia Afrin","orcid":"0000-0001-5063-9900","position":1,"is_corresponding":false},{"id":368552,"name":"Yingqiu Guo","orcid":"0000-0002-6772-6143","position":2,"is_corresponding":false},{"id":391865,"name":"Wenhua Chu","orcid":null,"position":3,"is_corresponding":false},{"id":301875,"name":"Tammie L.S. Benzinger","orcid":"0000-0002-8114-0552","position":4,"is_corresponding":false},{"id":227900,"name":"Buck E. Rogers","orcid":"0000-0001-8189-1797","position":5,"is_corresponding":false},{"id":323929,"name":"Joel R. Garbow","orcid":"0000-0002-0654-2703","position":6,"is_corresponding":false},{"id":52686,"name":"Joel S. Perlmutter","orcid":"0000-0003-3263-8917","position":7,"is_corresponding":false},{"id":391204,"name":"Dong Zhou","orcid":"0000-0002-6707-4878","position":8,"is_corresponding":false},{"id":364748,"name":"Jinbin Xu","orcid":"0000-0002-2120-8287","position":9,"is_corresponding":false},{"id":391202,"name":"Huaping Chen","orcid":"0000-0002-9835-5138","position":0,"is_corresponding":true}],"reference_count":49,"raw_metadata":null,"created_at":"2026-07-18T21:46:11.663457Z","pmid":"33238630","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}