RESUMO
BACKGROUND: Mast cells (MC) are powerful inflammatory immune sentinel cells that drive numerous allergic, inflammatory, and pruritic disorders when activated. MC-targeted therapies are approved in several disorders, yet many patients have limited benefit suggesting the need for approaches that more broadly inhibit MC activity. MCs require the KIT receptor and its ligand stem cell factor (SCF) for differentiation, maturation, and survival. Here we describe CDX-0159, an anti-KIT monoclonal antibody that potently suppresses MCs in human healthy volunteers. METHODS: CDX-0159-mediated KIT inhibition was tested in vitro using KIT-expressing immortalized cells and primary human mast cells. CDX-0159 safety and pharmacokinetics were evaluated in a 13-week good laboratory practice (GLP)-compliant cynomolgus macaque study. A single ascending dose (0.3, 1, 3, and 9 mg/kg), double-blinded placebo-controlled phase 1a human healthy volunteer study (n = 32) was conducted to evaluate the safety, pharmacokinetics, and pharmacodynamics of CDX-0159. RESULTS: CDX-0159 inhibits SCF-dependent KIT activation in vitro. Fc modifications in CDX-0159 led to elimination of effector function and reduced serum clearance. In cynomolgus macaques, multiple high doses were safely administered without a significant impact on hematology, a potential concern for KIT inhibitors. A single dose of CDX-0159 in healthy human subjects was generally well tolerated and demonstrated long antibody exposure. Importantly, CDX-0159 led to dose-dependent, profound suppression of plasma tryptase, a MC-specific protease associated with tissue MC burden, indicative of systemic MC suppression or ablation. CONCLUSION: CDX-0159 administration leads to systemic mast cell ablation and may represent a safe and novel approach to treat mast cell-driven disorders.
Assuntos
Anticorpos Monoclonais , Mastócitos , Proteínas Proto-Oncogênicas c-kit , Anticorpos Monoclonais/efeitos adversos , Anticorpos Monoclonais/farmacologia , Voluntários Saudáveis , Humanos , Mastócitos/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-kit/antagonistas & inibidores , Fator de Células-TroncoRESUMO
PURPOSE: Estrogen receptor (ER) alpha signaling is a known driver of ER-positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer. Combining endocrine therapy (ET) such as fulvestrant with CDK4/6, mTOR, or PI3K inhibitors has become a central strategy in the treatment of ER+ advanced breast cancer. However, suboptimal ER inhibition and resistance resulting from the ESR1 mutation dictates that new therapies are needed. EXPERIMENTAL DESIGN: A medicinal chemistry campaign identified vepdegestrant (ARV-471), a selective, orally bioavailable, and potent small molecule PROteolysis-TArgeting Chimera (PROTAC) degrader of ER. We used biochemical and intracellular target engagement assays to demonstrate the mechanism of action of vepdegestrant, and ESR1 wild-type (WT) and mutant ER+ preclinical breast cancer models to demonstrate ER degradation-mediated tumor growth inhibition (TGI). RESULTS: Vepdegestrant induced ≥90% degradation of wild-type and mutant ER, inhibited ER-dependent breast cancer cell line proliferation in vitro, and achieved substantial TGI (87%-123%) in MCF7 orthotopic xenograft models, better than those of the ET agent fulvestrant (31%-80% TGI). In the hormone independent (HI) mutant ER Y537S patient-derived xenograft (PDX) breast cancer model ST941/HI, vepdegestrant achieved tumor regression and was similarly efficacious in the ST941/HI/PBR palbociclib-resistant model (102% TGI). Vepdegestrant-induced robust tumor regressions in combination with each of the CDK4/6 inhibitors palbociclib, abemaciclib, and ribociclib; the mTOR inhibitor everolimus; and the PI3K inhibitors alpelisib and inavolisib. CONCLUSIONS: Vepdegestrant achieved greater ER degradation in vivo compared with fulvestrant, which correlated with improved TGI, suggesting vepdegestrant could be a more effective backbone ET for patients with ER+/HER2- breast cancer.
Assuntos
Neoplasias da Mama , Quinase 4 Dependente de Ciclina , Quinase 6 Dependente de Ciclina , Transdução de Sinais , Serina-Treonina Quinases TOR , Ensaios Antitumorais Modelo de Xenoenxerto , Humanos , Feminino , Animais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Neoplasias da Mama/metabolismo , Quinase 6 Dependente de Ciclina/antagonistas & inibidores , Quinase 4 Dependente de Ciclina/antagonistas & inibidores , Camundongos , Serina-Treonina Quinases TOR/metabolismo , Serina-Treonina Quinases TOR/antagonistas & inibidores , Linhagem Celular Tumoral , Transdução de Sinais/efeitos dos fármacos , Receptor alfa de Estrogênio/metabolismo , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/antagonistas & inibidores , Piperazinas/farmacologia , Piperazinas/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Inibidores de Fosfoinositídeo-3 Quinase/farmacologia , Inibidores de Fosfoinositídeo-3 Quinase/administração & dosagem , Receptores de Estrogênio/metabolismo , Piridinas/administração & dosagem , Piridinas/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Proliferação de Células/efeitos dos fármacosRESUMO
In phase I development, CDX-3379, an anti-ErbB3 monoclonal antibody, showed promising molecular and antitumor activity in head and neck squamous cell carcinoma (HNSCC), alone or in combination with cetuximab. Preliminary biomarker data raised the hypothesis of enhanced response in tumors harboring FAT1 mutations. This phase II, multicenter trial used a Simon 2-stage design to investigate the efficacy of CDX-3379 and cetuximab in 30 patients with recurrent/metastatic, HPV-negative, cetuximab-resistant HNSCC. The primary endpoint was objective response rate (ORR). Secondary endpoints included ORR in patients with somatic FAT1 mutations, progression-free survival (PFS), overall survival (OS), and safety. Thirty patients were enrolled from March 2018 to September 2020. The ORR in genomically unselected patients was 2/30 (6.7%; 95% confidence interval [CI], 0.8-22.1). Median PFS and OS were 2.2 (95% CI: 1.3-3.6) and 6.6 months (95% CI: 2.7-7.5), respectively. Tissue was available in 27 patients including one of two responders. ORR was 1/10 (complete response; 10%; 95% CI 0.30-44.5) in the FAT1-mutated versus 0/17 (0%; 95% CI: 0-19.5) in the FAT1-wildtype cohorts. Sixteen patients (53%) experienced treatment-related adverse events (AEs) ≥ grade 3. The most common AEs were diarrhea (83%) and acneiform dermatitis (53%). Dose modification was required in 21 patients (70%). The modest ORR coupled with excessive, dose-limiting toxicity of this combination precludes further clinical development. Dual ErbB3-EGFR inhibition remains of scientific interest in HPV-negative HNSCC. Should more tolerable combinations be identified, development in an earlier line of therapy and prospective evaluation of the FAT1 hypothesis warrant consideration.
RESUMO
PURPOSE: ErbB3 and its ligand neuregulin-1 (NRG1) are widely expressed in head and neck squamous cell carcinoma (HNSCC) and associated with tumor progression. A "window-of-opportunity" study (NCT02473731) was conducted to evaluate the pharmacodynamic effects of CDX-3379, an anti-ErbB3 mAb, in patients with HNSCC. PATIENTS AND METHODS: Twelve patients with newly diagnosed, operable HNSCC received two infusions of CDX-3379 (1,000 mg) at a 2-week interval prior to tumor resection. The primary study objective was to achieve ≥50% reduction in tumor ErbB3 signaling (phosphorylation of ErbB3; pErbB3) in ≥30% of patients. Other potential tumor biomarkers, pharmacokinetics, safety, and tumor measurements were also assessed. RESULTS: pErbB3 was detectable in all tumors prior to treatment and decreased for 10 of 12 (83%) patients following CDX-3379 dosing, with ≥50% reduction in 7 of 12 (58%; P = 0.04; 95% confidence interval, 27.7%-84.8%). Target trough CDX-3379 serum levels were achieved in all patients. CDX-3379 treatment-related toxicity was grade 1-2 and included diarrhea, fatigue, and acneiform dermatitis. Five of 12 (42%) patients had shrinkage in tumor burden, including a marked clinical response in a patient with human papillomavirus-negative oral cavity HNSCC. All patients with tumor shrinkage had tumors that expressed both NRG1 and ErbB3 and demonstrated reduced pErbB3 with CDX-3379 treatment. CONCLUSIONS: This study demonstrates that CDX-3379 can inhibit tumor ErbB3 phosphorylation in HNSCC. CDX-3379 was well tolerated and associated with measurable tumor regression. A phase II study (NCT03254927) has been initiated to evaluate CDX-3379 in combination with cetuximab for patients with advanced HNSCC.
Assuntos
Antineoplásicos Imunológicos/uso terapêutico , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Receptor ErbB-3/antagonistas & inibidores , Carcinoma de Células Escamosas de Cabeça e Pescoço/tratamento farmacológico , Anticorpos Monoclonais/efeitos adversos , Anticorpos Monoclonais/farmacocinética , Anticorpos Monoclonais/uso terapêutico , Antineoplásicos Imunológicos/efeitos adversos , Antineoplásicos Imunológicos/farmacocinética , Biomarcadores Tumorais/metabolismo , Feminino , Neoplasias de Cabeça e Pescoço/imunologia , Neoplasias de Cabeça e Pescoço/metabolismo , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Neuregulina-1/metabolismo , Receptor ErbB-3/imunologia , Receptor ErbB-3/metabolismo , Transdução de Sinais , Carcinoma de Células Escamosas de Cabeça e Pescoço/imunologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologiaRESUMO
PURPOSE: Targeting of KIT and platelet-derived growth factor receptor (PDGFR) tyrosine kinases by imatinib is an effective anticancer strategy. However, mutations of the gatekeeper residue (T670 in KIT and T681 in PDGFRbeta) render the two kinases resistant to imatinib. The aim of this study was to evaluate whether sorafenib (BAY 43-9006), a multitargeted ATP-competitive inhibitor of KIT and PDGFR, was active against imatinib-resistant KIT and PDGFRbeta kinases. EXPERIMENTAL DESIGN: We used in vitro kinase assays and immunoblot with phosphospecific antibodies to determine the activity of sorafenib on KIT and PDGFRbeta kinases. We also exploited reporter luciferase assays to measure the effects of sorafenib on KIT and PDGFRbeta downstream signaling events. The activity of sorafenib on interleukin-3-independent proliferation of Ba/F3 cells expressing oncogenic KIT or its imatinib-resistant T670I mutant was also tested. RESULTS: Sorafenib efficiently inhibited gatekeeper mutants of KIT and PDGFRbeta (IC(50) for KIT T670I, 60 nmol/L; IC(50) for PDGFRbeta T681I, 110 nmol/L). Instead, it was less active against activation loop mutants of the two receptors (IC(50) for KIT D816V, 3.8 micromol/L; IC(50) for PDGFRbeta D850V, 1.17 micromol/L) that are also imatinib-resistant. Sorafenib blocked receptor autophosphorylation and signaling of KIT and PDGFRbeta gatekeeper mutants in intact cells as well as activation of AP1-responsive and cyclin D1 gene promoters, respectively. Finally, the compound inhibited KIT-dependent proliferation of Ba/F3 cells expressing the oncogenic KIT mutant carrying the T670I mutation. CONCLUSIONS: Sorafenib might be a promising anticancer agent for patients carrying KIT and PDGFRbeta gatekeeper mutations.
Assuntos
Benzenossulfonatos/farmacologia , Mutação , Piperazinas/farmacologia , Proteínas Proto-Oncogênicas c-kit/metabolismo , Proteínas Proto-Oncogênicas c-sis/genética , Proteínas Proto-Oncogênicas c-sis/metabolismo , Piridinas/farmacologia , Pirimidinas/farmacologia , Trifosfato de Adenosina/metabolismo , Animais , Antineoplásicos/farmacologia , Benzamidas , Ligação Competitiva , Proliferação de Células , Humanos , Mesilato de Imatinib , Concentração Inibidora 50 , Interleucina-3/metabolismo , Camundongos , Niacinamida/análogos & derivados , Compostos de Fenilureia , SorafenibeRESUMO
A high-throughput mass spectrometry assay to measure the catalytic activity of phosphatidylserine decarboxylase (PISD) is described. PISD converts phosphatidylserine to phosphatidylethanolamine during lipid synthesis. Traditional methods of measuring PISD activity are low throughput and unsuitable for the high-throughput screening of large compound libraries. The high-throughput mass spectrometry assay directly measures phosphatidylserine and phosphatidylethanolamine using the RapidFiretrade mark platform at a rate of 1 sample every 7.5 s. The assay is robust, with an average Z' value of 0.79 from a screen of 9920 compounds. Of 60 compounds selected for confirmation, 54 are active in dose-response studies. The application of high-throughput mass spectrometry permitted a high-quality screen to be performed for an otherwise intractable target.
Assuntos
Carboxiliases/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Espectrometria de Massas/métodos , Carboxiliases/análise , Carboxiliases/genética , Linhagem Celular , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Estabilidade Enzimática , Congelamento , Humanos , Rim/citologia , Cinética , Plasmídeos , Proteínas Recombinantes de Fusão/antagonistas & inibidores , Robótica , Análise de Sequência de DNA , TransfecçãoRESUMO
Purpose: KTN0158 is a novel anti-KIT antibody that potently inhibits wild-type and mutant KIT. This study evaluated the safety, biologic activity, and pharmacokinetic/pharmacodynamics profile of KTN0158 in dogs with spontaneous mast cell tumors (MCT) as a prelude to human clinical applications.Experimental Design: Cell proliferation, KIT phosphorylation, and mast cell degranulation were evaluated in vitro KTN0158 was administered to 4 research dogs to assess clinical effects and cutaneous mast cell numbers. Thirteen dogs with spontaneous MCT were enrolled into a prospective phase I dose-escalating open-label clinical study of KTN0158 evaluating 3 dose levels and 2 schedules and with weekly assessments for response and clinical toxicities.Results: KTN0158 was a potent inhibitor of human and dog KIT activation and blocked mast cell degranulation in vitro In dogs, KTN0158 was well tolerated and reduced cutaneous mast cell numbers in a dose-dependent manner. Clinical benefit of KTN0158 administration in dogs with MCT (n = 5 partial response; n = 7 stable disease) was observed regardless of KIT mutation status, and decreased KIT phosphorylation was demonstrated in tumor samples. Histopathology after study completion demonstrated an absence of neoplastic cells in the primary tumors and/or metastatic lymph nodes from 4 dogs. Reversible hematologic and biochemical adverse events were observed at doses of 10 and 30 mg/kg. The MTD was established as 10 mg/kg.Conclusions: KTN0158 inhibits KIT phosphorylation, demonstrates an acceptable safety profile in dogs, and provides objective responses in canine MCT patients with and without activating KIT mutations, supporting future clinical evaluation of KTN0158 in people. Clin Cancer Res; 23(10); 2565-74. ©2016 AACR.
Assuntos
Anticorpos Monoclonais/administração & dosagem , Doenças do Cão/tratamento farmacológico , Proteínas Proto-Oncogênicas c-kit/imunologia , Animais , Anticorpos Monoclonais/imunologia , Proliferação de Células/efeitos dos fármacos , Doenças do Cão/genética , Doenças do Cão/imunologia , Cães , Feminino , Humanos , Mastócitos/efeitos dos fármacos , Mastócitos/imunologia , Mutação , FosforilaçãoRESUMO
The receptor tyrosine kinase KIT is an established oncogenic driver of tumor growth in certain tumor types, including gastrointestinal stromal tumors, in which constitutively active mutant forms of KIT represent an actionable target for small-molecule tyrosine kinase inhibitors. There is also considerable potential for KIT to influence tumor growth indirectly based on its expression and function in cell types of the innate immune system, most notably mast cells. We have evaluated syngeneic mouse tumor models for antitumor effects of an inhibitory KIT mAb, dosed either alone or in combination with immune checkpoint inhibitors. Anti-KIT mAb treatment enhanced the antitumor activity of anti-CTLA-4 and anti-PD-1 mAbs, and promoted immune responses by selectively reducing the immunosuppressive monocytic myeloid-derived suppressor cell population and by restoring CD8+ and CD4+ T-cell populations to levels observed in naïve mice. These data provide a rationale for clinical investigation of the human KIT-specific mAb KTN0158 in novel immuno-oncology combinations with immune checkpoint inhibitors and other immunotherapeutic agents across a range of tumor types. Mol Cancer Ther; 16(4); 671-80. ©2017 AACR.
Assuntos
Anticorpos Monoclonais/administração & dosagem , Antígeno CTLA-4/antagonistas & inibidores , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Neoplasias do Colo/tratamento farmacológico , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-kit/antagonistas & inibidores , Animais , Anticorpos Monoclonais/farmacologia , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD8-Positivos/efeitos dos fármacos , Linhagem Celular Tumoral , Neoplasias do Colo/imunologia , Neoplasias do Colo/metabolismo , Citotoxicidade Imunológica/efeitos dos fármacos , Sinergismo Farmacológico , Humanos , Terapia de Imunossupressão , Camundongos , Células Supressoras Mieloides/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Innate immune cells such as mast cells and myeloid-derived suppressor cells are key components of the tumor microenvironment. Recent evidence indicates that levels of myeloid-derived suppressor cells in melanoma patients are associated with poor survival to checkpoint inhibitors. This suggests that targeting both the innate and adaptive suppressive components of the immune system will maximize clinical benefit and elicit more durable responses in cancer patients. Preclinical data suggest that targeting signaling by the receptor tyrosine kinase KIT, particularly on mast cells, may modulate innate immune cell numbers and activity in tumors. Here, we review data highlighting the importance of the KIT signaling in regulating antitumor immune responses and the potential benefit of combining selective KIT inhibitors with immune checkpoint inhibitors.
Assuntos
Antineoplásicos/uso terapêutico , Imunoterapia/métodos , Células Supressoras Mieloides/imunologia , Neoplasias/terapia , Proteínas Proto-Oncogênicas c-kit/metabolismo , Animais , Receptores Coestimuladores e Inibidores de Linfócitos T/antagonistas & inibidores , Quimioterapia Combinada , Humanos , Imunidade Inata , Terapia de Alvo Molecular , Neoplasias/imunologia , Transdução de Sinais , Evasão Tumoral , Microambiente TumoralRESUMO
PURPOSE: Cross-talk between type I IGF receptor (IGF1R), insulin receptor (INSR), and epidermal growth factor receptor (EGFR) mediates resistance to individual receptor blockade. This study aimed to determine the MTD, safety, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of linsitinib, a potent oral IGF1R/INSR inhibitor, with EGFR inhibitor erlotinib. EXPERIMENTAL DESIGN: This open-label, dose-escalation study investigated linsitinib schedules S1: once daily intermittent (days 1-3 weekly); S2, once daily continuous; S3, twice-daily continuous; each with erlotinib 100-150 mg once daily; and a non-small cell lung cancer (NSCLC) expansion cohort. RESULTS: Ninety-five patients were enrolled (S1, 44; S2, 24; S3, 12; expansion cohort, 15) and 91 treated. Seven experienced dose-limiting toxicities: QTc prolongation (3), abnormal liver function (2), hyperglycemia (1), and anorexia (1). Common adverse events included drug eruption (84%), diarrhea (73%), fatigue (68%), nausea (58%), vomiting (40%). MTDs for linsitinib/erlotinib were 450/150 mg (S1), 400/100 mg (S2). On the basis of prior monotherapy data, S3 dosing at 150 mg twice daily/150 mg once daily was the recommended phase II dose for the expansion cohort. There was no evidence of drug-drug interaction. Pharmacodynamic data showed IGF-1 elevation and reduced IGF1R/INSR phosphorylation, suggesting pathway inhibition. Across schedules, 5/75 (7%) evaluable patients experienced partial responses: spinal chordoma (268+ weeks), rectal cancer (36 weeks), three NSCLCs including 2 adenocarcinomas (16, 72 weeks), 1 squamous wild-type EGFR NSCLC (36 weeks). Disease control (CR+PR+SD) occurred in 38 of 75 (51%), and 28 of 91 (31%) patients were on study >12 weeks. CONCLUSIONS: The linsitinib/erlotinib combination was tolerable with preliminary evidence of activity, including durable responses in cases unlikely to respond to erlotinib monotherapy. Clin Cancer Res; 22(12); 2897-907. ©2016 AACR.
Assuntos
Antineoplásicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Cloridrato de Erlotinib/uso terapêutico , Imidazóis/uso terapêutico , Neoplasias Pulmonares/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Pirazinas/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígenos CD , Antineoplásicos/efeitos adversos , Relação Dose-Resposta a Droga , Receptores ErbB/antagonistas & inibidores , Cloridrato de Erlotinib/efeitos adversos , Cloridrato de Erlotinib/farmacocinética , Feminino , Humanos , Imidazóis/efeitos adversos , Imidazóis/farmacocinética , Masculino , Dose Máxima Tolerável , Pessoa de Meia-Idade , Inibidores de Proteínas Quinases/efeitos adversos , Pirazinas/efeitos adversos , Pirazinas/farmacocinética , Receptor IGF Tipo 1 , Receptor de Insulina/antagonistas & inibidores , Receptores de Somatomedina/antagonistas & inibidores , Adulto JovemRESUMO
Protein kinases play a critical regulatory role in essentially every aspect of cell biology. Of the 518 known kinases, the most successful class for drug targeting is the receptor tyrosine kinase (RTK) family consisting of 58 distinct and diverse members. RTKs regulate a broad range of cellular functions, including proliferation, differentiation, survival, and apoptosis and have been intensively studied in development and cancer. Targeting of RTKs has resulted in many marketed small molecule and antibody-based drugs in a number of different solid tumors and hematological malignancies, and more recently in inflammatory diseases such as idiopathic pulmonary fibrosis. In this review, we discuss some of the RTKs in cancer in which drugs targeting the ErbB family (EGFR, HER2, and ErbB3) and KIT have had meaningful clinical benefit to cancer patients, RTKs' emerging role in regulating innate immunity, and the potential to explore targeting RTKs outside of oncology.
Assuntos
Antineoplásicos Imunológicos/uso terapêutico , Inflamação/metabolismo , Terapia de Alvo Molecular , Neoplasias/metabolismo , Receptores Proteína Tirosina Quinases/antagonistas & inibidores , Animais , Antineoplásicos Imunológicos/farmacologia , Feminino , Humanos , Inflamação/tratamento farmacológico , Masculino , Neoplasias/tratamento farmacológico , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de SinaisRESUMO
PURPOSE: OSI-930 is a novel, potent, oral small-molecule receptor tyrosine kinase inhibitor, predominantly against VEGF receptors (VEGFR), c-Kit, and platelet-derived growth factor receptors. A phase I trial was undertaken to determine safety, maximum-tolerated dose (MTD), pharmacokinetics, pharmacodynamics, and antitumor activity of OSI-930 in patients with advanced solid tumors. EXPERIMENTAL DESIGN: OSI-930 was administered once or twice a day using a modified accelerated titration design. Pharmacokinetics and plasma soluble VEGFR2 (sVEGFR2) studies were undertaken. Dynamic contrast-enhanced MRI (DCE-MRI) and 2[18F]fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) MTD expansion cohorts were conducted. RESULTS: Fifty-eight patients received OSI-930 in 2 schedules; once a day schedule: 12 patients at doses up to 1,600 mg without reaching MTD; twice a day schedule: 46 patients at 400 mg (n = 7), 500 mg (n = 31), and 600 mg (n = 8). Dose-limiting toxicities were observed at 600 mg twice a day (n = 3): G3 rash (n = 2) and G4 γ-glutamyltransferase, establishing the MTD at 500 mg twice a day. Common G1-2 toxicities included fatigue, diarrhea, nausea, and rash. Antitumor responses were seen in 2 patients with advanced ovarian cancer [Response Evaluation Criteria in Solid Tumors (RECIST) partial response (PR) (n = 1); GCIG CA125 response (n = 1)]. Eleven of 19 heavily pretreated imatinib-resistant patients with gastrointestinal stromal tumors achieved RECIST stable disease (median duration: 126 days), with FDG-PET scans showing PRs in 4 of 9 patients. OSI-930 exposure increased with dose; substantial decreases in sVEGFR levels were observed with OSI-930 twice a day doses ≥400 mg, while DCE-MRI responses were shown in 4 of 6 patients. CONCLUSIONS: OSI-930 is safe and well tolerated, with pharmacokinetic-pharmacodynamic data supporting proof-of-mechanism with clinically relevant antitumor activity.