RESUMO
PURPOSE: PSMA (prostate-specific membrane antigen) is highly expressed on prostate cancer (PrCa) cells and extensively used as a homing target for PrCa treatment. Most prominently, PSMA-targeting conjugate PSMA-617, carrying a DOTA chelator and labeled with therapeutic radionuclides like beta-emitting lutetium-177 or alpha-emitting actinium-225, has shown clinical activity in PrCa patients. We sought to develop PSMA-targeting small molecule (SMOL) conjugates that show high uptake in PSMA-expressing tumors and fast clearance, and can easily be labeled with the alpha emitter thorium-227 (half-life 18.7 days). METHODS: A novel linker motif with improved competition against 3H-PSMA-617 on PSMA-expressing LNCaP cells was identified. A 2,3-hydroxypyridinone chelator modified with carboxyl groups (carboxy-HOPO) with increased hydrophilicity and robust labeling with thorium-227 was developed and allowed the synthesis of mono-, di-, tri-, and tetrameric conjugates. The resulting monomeric and multimeric PSMA SMOL-TTCs (targeted thorium conjugate) were evaluated for cellular binding, internalization, and antiproliferative activity. The in vivo antitumor efficacy of the PSMA SMOL-TTCs was determined in ST1273 and KUCaP-1 PrCa models in mice, and their biodistribution was assessed in cynomolgus monkeys, minipigs, and mice. RESULTS: The monomeric and multimeric PSMA SMOL conjugates were readily labeled with thorium-227 at room temperature and possessed high stability and good binding, internalization, and antiproliferative activity in vitro. In vivo, the monomeric, dimeric, and trimeric PSMA SMOL-TTCs showed fast clearance, potent antitumor efficacy, and high uptake and retention in prostate tumors in mice. No major uptake or retention in other organs was observed beyond kidneys. Low uptake of free thorium-227 into bone confirmed high complex stability in vivo. Salivary gland uptake remained inconclusive as mini pigs were devalidated as a relevant model and imaging controls failed in cynomolgus monkeys. CONCLUSION: Monomeric and multimeric PSMA SMOL-TTCs show high tumor uptake and fast clearance in preclinical models and warrant further therapeutic exploration.
Assuntos
Neoplasias da Próstata , Tório , Masculino , Humanos , Animais , Camundongos , Suínos , Distribuição Tecidual , Macaca fascicularis/metabolismo , Porco Miniatura/metabolismo , Glutamato Carboxipeptidase II/metabolismo , Antígenos de Superfície/metabolismo , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/metabolismo , Compostos Radiofarmacêuticos , Quelantes/química , Linhagem Celular TumoralRESUMO
Inhibition of intracellular nicotinamide phosphoribosyltransferase (NAMPT) represents a new mode of action for cancer-targeting antibody-drug conjugates (ADCs) with activity also in slowly proliferating cells. To extend the repertoire of available effector chemistries, we have developed a novel structural class of NAMPT inhibitors as ADC payloads. A structure-activity relationship-driven approach supported by protein structural information was pursued to identify a suitable attachment point for the linker to connect the NAMPT inhibitor with the antibody. Optimization of scaffolds and linker structures led to highly potent effector chemistries which were conjugated to antibodies targeting C4.4a (LYPD3), HER2 (c-erbB2), or B7H3 (CD276) and tested on antigen-positive and -negative cancer cell lines. Pharmacokinetic studies, including metabolite profiling, were performed to optimize the stability and selectivity of the ADCs and to evaluate potential bystander effects. Optimized NAMPTi-ADCs demonstrated potent in vivo antitumor efficacy in target antigen-expressing xenograft mouse models. This led to the development of highly potent NAMPT inhibitor ADCs with a very good selectivity profile compared with the corresponding isotype control ADCs. Moreover, we demonstrateâto our knowledge for the first timeâthe generation of NAMPTi payload metabolites from the NAMPTi-ADCs in vitro and in vivo. In conclusion, NAMPTi-ADCs represent an attractive new payload class designed for use in ADCs for the treatment of solid and hematological cancers.
Assuntos
Antineoplásicos , Imunoconjugados , Neoplasias , Nicotinamida Fosforribosiltransferase , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Antígenos B7 , Linhagem Celular Tumoral , Humanos , Imunoconjugados/química , Imunoconjugados/farmacologia , Camundongos , Neoplasias/tratamento farmacológico , Neoplasias/enzimologia , Nicotinamida Fosforribosiltransferase/antagonistas & inibidores , Nicotinamida Fosforribosiltransferase/química , Relação Estrutura-Atividade , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Selective inhibition of exclusively transcription-regulating positive transcription elongation factor b/CDK9 is a promising new approach in cancer therapy. Starting from atuveciclib, the first selective CDK9 inhibitor to enter clinical development, lead optimization efforts aimed at identifying intravenously (iv) applicable CDK9 inhibitors with an improved therapeutic index led to the discovery of the highly potent and selective clinical candidate VIP152. The evaluation of various scaffold hops was instrumental in the identification of VIP152, which is characterized by the underexplored benzyl sulfoximine group. VIP152 exhibited the best preclinical overall profile in vitro and in vivo, including high efficacy and good tolerability in xenograft models in mice and rats upon once weekly iv administration. VIP152 has entered clinical trials for the treatment of cancer with promising longterm, durable monotherapy activity in double-hit diffuse large B-cell lymphoma patients.
Assuntos
Antineoplásicos/farmacologia , Quinase 9 Dependente de Ciclina/antagonistas & inibidores , Descoberta de Drogas , Leucemia Mieloide Aguda/tratamento farmacológico , Inibidores de Proteínas Quinases/farmacologia , Animais , Antineoplásicos/administração & dosagem , Antineoplásicos/química , Proliferação de Células/efeitos dos fármacos , Quinase 9 Dependente de Ciclina/metabolismo , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Humanos , Injeções Intravenosas , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patologia , Camundongos , Camundongos Nus , Estrutura Molecular , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Inibidores de Proteínas Quinases/administração & dosagem , Inibidores de Proteínas Quinases/química , Ratos , Relação Estrutura-AtividadeRESUMO
Since the late 1980s, mutations in the RAS genes have been recognized as major oncogenes with a high occurrence rate in human cancers. Such mutations reduce the ability of the small GTPase RAS to hydrolyze GTP, keeping this molecular switch in a constitutively active GTP-bound form that drives, unchecked, oncogenic downstream signaling. One strategy to reduce the levels of active RAS is to target guanine nucleotide exchange factors, which allow RAS to cycle from the inactive GDP-bound state to the active GTP-bound form. Here, we describe the identification of potent and cell-active small-molecule inhibitors which efficiently disrupt the interaction between KRAS and its exchange factor SOS1, a mode of action confirmed by a series of biophysical techniques. The binding sites, mode of action, and selectivity were elucidated using crystal structures of KRASG12C-SOS1, SOS1, and SOS2. By preventing formation of the KRAS-SOS1 complex, these inhibitors block reloading of KRAS with GTP, leading to antiproliferative activity. The final compound 23 (BAY-293) selectively inhibits the KRAS-SOS1 interaction with an IC50 of 21 nM and is a valuable chemical probe for future investigations.
Assuntos
Proteínas Proto-Oncogênicas p21(ras)/antagonistas & inibidores , Proteína SOS1/antagonistas & inibidores , Linhagem Celular , Cristalografia por Raios X , Descoberta de Drogas , Transferência Ressonante de Energia de Fluorescência , Ensaios de Triagem em Larga Escala , Humanos , Ligação Proteica , Proteínas Proto-Oncogênicas p21(ras)/química , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Proteína SOS1/química , Proteína SOS1/metabolismo , Transdução de SinaisRESUMO
PURPOSE: Prostate-specific membrane antigen (PSMA) is a transmembrane protein overexpressed in prostate cancer and is therefore being explored as a biomarker for diagnosing and staging of the disease. Here we report preclinical data on BAY 1075553 (a 9:1 mixture of (2S,4S)- and (2R,4S)-2-[(18)F]fluoro-4-phosphonomethyl-pentanedioic acid), a novel (18)F-labelled small molecule inhibitor of PSMA enzymatic activity, which can be efficiently synthesized from a direct radiolabelling precursor. METHODS: The (18)F-radiolabelled stereoisomers of 2-[(18)F]fluoro-4-(phosphonomethyl)-pentanedioic acid were synthesized from their respective isomerically pure precursors dimethyl 2-{[bis(benzyloxy)phosphoryl]methyl}-4-(tosyloxy)pentanedioate. In vivo positron emission tomography (PET) imaging and biodistribution studies were conducted in mice bearing LNCaP, 22Rv1 and PC-3 tumours. Pharmacokinetic parameters and dosimetry estimates were calculated based on biodistribution studies in rodents. For non-clinical safety assessment (safety pharmacology, toxicology) to support a single-dose human microdose study, off-target effects in vitro, effects on vital organ functions (cardiovascular in dogs, nervous system in rats), mutagenicity screens and an extended single-dose study in rats were conducted with the non-radioactive racemic analogue of BAY 1075553. RESULTS: BAY 1075553 showed high tumour accumulation specific to PSMA-positive tumour-bearing mice and was superior to other stereoisomers tested. Fast clearance of BAY 1075553 resulted overall in low background signals in other organs except for high uptake into kidney and bladder which was mainly caused by renal elimination of BAY 1075553. A modest uptake into bone was observed which decreased over time indicating organ-specific uptake as opposed to defluorination of BAY 1075553 in vivo. Biodistribution studies found highest organ doses for kidneys and the urinary bladder wall resulting in a projected effective dose (ED) in humans of 0.0219 mSv/MBq. Non-clinical safety studies did not show off-target activity, effects on vital organs function or dose-dependent adverse effects. CONCLUSION: BAY 1075553 was identified as a promising PET tracer for PSMA-positive prostate tumours in preclinical studies. BAY 1075553 can be produced using a robust, direct radiosynthesis procedure. Pharmacokinetic, toxicology and safety pharmacology studies support the application of BAY 1075553 in a first-in-man microdose study with single i.v. administration.
Assuntos
Radioisótopos de Flúor , Glutamato Carboxipeptidase II/antagonistas & inibidores , Glutaratos , Organofosfonatos , Tomografia por Emissão de Pósitrons/métodos , Neoplasias da Próstata/diagnóstico por imagem , Compostos Radiofarmacêuticos , Animais , Antígenos de Superfície , Cães , Feminino , Glutaratos/efeitos adversos , Glutaratos/farmacocinética , Glutaratos/farmacologia , Humanos , Marcação por Isótopo , Masculino , Camundongos , Organofosfonatos/efeitos adversos , Organofosfonatos/farmacocinética , Organofosfonatos/farmacologia , Traçadores Radioativos , Radioquímica , Compostos Radiofarmacêuticos/efeitos adversos , Compostos Radiofarmacêuticos/farmacocinética , Compostos Radiofarmacêuticos/farmacologia , Ratos , Segurança , EstereoisomerismoRESUMO
For prostate cancer, prostate specific membrane antigen (PSMA) has been identified as a diagnostic and therapeutic target. Fluorinated derivatives of 2-(phosphonomethyl)pentanedioic acid were designed and synthesized to explore whether this fluorine-substituent is tolerated in the pentanedioic acid moiety that is common to almost all PSMA targeting small molecule inhibitors. The binding affinities of the racemic and individual stereoisomers of 2-fluoro-4-(phosphonomethyl)pentanedioic acid were determined and showed that the introduction of fluorine was well tolerated. The radiosynthesis of the analogous 2-[(18)F]fluoro-4-(phosphonomethyl)pentanedioic acid was developed and evaluated in vivo with the PSMA positive LNCaP human prostate cancer cell. The biological results demonstrated specific binding of the tracer to PSMA positive tumors in mice. These results warrant the further evaluation of this class of compounds as radiolabeled tracers for the detection and staging of prostate cancer.