cabozantinib and Prostatic-Neoplasms

This review will describe the management of patients with prostate cancer and bone metastases with a particular emphasis on recent advances in this area.. Two osteoclast-targeted agents have been shown to decrease the incidence of skeletal-related events in patients with metastatic castration-resistant prostate cancer (mCRPC) and bone metastases. These agents are the bisphosphonate zoledronic acid and the monoclonal antibody denosumab. Recent advances in the field include the approval of several agents shown to extend survival in mCRPC. Among these agents, the androgen-pathway inhibitors, abiraterone and enzalutamide, are shown to decrease the incidence of skeletal-related events, whereas the radiopharmaceutical radium-223 is shown to reduce the incidence of symptomatic skeletal event. Cabozantinib, an agent in development, has shown encouraging activity in patients with mCRPC and bone metastases; definitive phase III trials of this agent are underway. Phase III metastasis-prevention trials are also underway in nonmetastatic CRPC.. Osteoclast-targeted agents reduce skeletal-related events in mCRPC. Disease-modifying agents also reduce the skeletal morbidity associated with mCRPC. Multiple agents are now available to reduce the skeletal morbidity of prostate cancer, whereas agents in development may provide additional options in the future.

Topics: Androstenes; Anilides; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Benzamides; Bone Density Conservation Agents; Bone Neoplasms; Denosumab; Diphosphonates; Fractures, Spontaneous; Humans; Imidazoles; Male; Nitriles; Phenylthiohydantoin; Prostatic Neoplasms; Prostatic Neoplasms, Castration-Resistant; Pyridines; Radioisotopes; Radium; Zoledronic Acid

Improved understanding of mechanisms underlying metastatic castration-resistant prostate cancer (mCRPC) progression has led to the recognition of multiple molecular targets and advances in the therapeutic landscape. The addition of abiraterone acetate, sipuleucel-T, cabazitaxel, and denosumab to the therapeutic armamentarium and the impending addition of MDV-3100 and radium-223 underscore the importance of androgen pathway inhibition, immunotherapy, tubulin antagonism, and pathophysiology of bone metastasis.. Review the next generation of molecular targets in mCRPC.. Medline databases were searched for >100 original articles published as of October 18, 2011, with the search terms metastatic castration-resistant prostate cancer, targeted therapy, biologic agents, and immunotherapy. Proceedings from the last 5 yr of conferences of the American Society of Clinical Oncology, American Urological Association, European Society of Medical Oncology, and the European Association of Urology were also searched. We included novel and promising drugs that have reached clinical trial evaluation.. The major findings were addressed in an evidence-based fashion. Prospective trials and important preclinical data were analyzed.. mCRPC is a disease with multiple molecular drivers. Molecular pathways being targeted in ongoing phase 3 trials are androgen signaling (MDV3100, TAK700), immunoregulatory pathways (ipilimumab, Prostvac-VF-TRICOM), Src (dasatinib), Met (cabozantinib), clusterin (custirsen), and angiogenesis (aflibercept, tasquinimod). The strides made in identifying multiple other novel molecular targets offer potential opportunities for further improving outcomes.

Topics: Abiraterone Acetate; Androstadienes; Anilides; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Benzamides; Bone Neoplasms; Cancer Vaccines; Carcinoma; Clinical Trials, Phase III as Topic; Clusterin; Dasatinib; Denosumab; Humans; Ipilimumab; Male; Nitriles; Orchiectomy; Phenylthiohydantoin; Prostatic Neoplasms; Pyridines; Pyrimidines; Quinolines; Quinolones; Radium; Receptors, Vascular Endothelial Growth Factor; Recombinant Fusion Proteins; Taxoids; Thiazoles; Tissue Extracts; Treatment Outcome; Vaccines, Synthetic

Antiangiogenic therapy has been successful for the treatment of solid tumors. Several strategies have been used to target angiogenesis in prostate cancer. These strategies include blocking proangiogenic factors via monoclonal antibodies or small molecule inhibitors targeting downstream signaling effector pathways, or using agents with immune-modulatory effects. This review examines the general concepts of tumor angiogenesis and the key clinical trials that have used these agents and other novel biologics in prostate cancer. Targeting angiogenesis is still a promising treatment strategy in prostate cancer with a rational trial design and combination approach.

Topics: Angiogenesis Inhibitors; Anilides; Antibodies, Monoclonal, Humanized; Bevacizumab; Disease Progression; Drug Therapy, Combination; Humans; Indoles; Male; Prostatic Neoplasms; Pyridines; Pyrroles; Signal Transduction; Sunitinib; Thalidomide; Vascular Endothelial Growth Factor A

Recent advances in tumor biology have made remarkable achievements in the development of therapy for metastatic castrate-resistant prostate cancer. These advances reflect a growing appreciation for the role of the tumor microenvironment in promoting prostate cancer progression. Prostate cancer is no longer viewed predominantly as a disease of abnormally proliferating epithelial cells but rather as a disease of complex interactions between prostate cancer epithelial cells (epithelial compartment) and the surrounding tissues (stromal compartment) in which they reside. For example, prostate cancers frequently metastasize to bone, an organ that contains a microenvironment rich in extracellular matrix proteins and stromal cells including hematopoietic cells, osteoblasts, osteoclasts fibroblasts, endothelial cells, adipocytes, immune cells, and mesenchymal stem cells. Multiple signaling pathways provide crosstalk between the epithelial and the stromal compartments to enhance tumor growth, including androgen receptor signaling, tyrosine kinase receptor signaling, and immune surveillance. The rationale to disrupt this "two-compartment" crosstalk has led to the development of drugs that target tumor stromal elements in addition to the cancer epithelial cell.

Topics: Androstenes; Androstenols; Angiogenesis Inhibitors; Anilides; Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Antineoplastic Agents, Hormonal; Atrasentan; Benzamides; Bevacizumab; Biomarkers, Tumor; Bone Remodeling; Cancer Vaccines; Clinical Trials as Topic; Clusterin; Dasatinib; Denosumab; Endothelin-1; Humans; Immunotherapy; Indoles; Ipilimumab; Male; Mice; Mice, SCID; Molecular Targeted Therapy; Nitriles; Orchiectomy; Phenylthiohydantoin; Prostate-Specific Antigen; Prostatic Neoplasms; Pyridines; Pyrimidines; Pyrroles; Pyrrolidines; RANK Ligand; Receptor Cross-Talk; Receptors, Androgen; Signal Transduction; Sunitinib; Taxoids; Thiazoles; Tissue Extracts; Treatment Failure; Tumor Microenvironment; Xenograft Model Antitumor Assays

Cabozantinib (XL184) is an orally bioavailable tyrosine kinase inhibitor with activity against MET and vascular endothelial growth factor receptor 2. We evaluated the activity of cabozantinib in patients with castration-resistant prostate cancer (CRPC) in a phase II randomized discontinuation trial with an expansion cohort.. Patients received 100 mg of cabozantinib daily. Those with stable disease per RECIST at 12 weeks were randomly assigned to cabozantinib or placebo. Primary end points were objective response rate at 12 weeks and progression-free survival (PFS) after random assignment.. One hundred seventy-one men with CRPC were enrolled. Random assignment was halted early based on the observed activity of cabozantinib. Seventy-two percent of patients had regression in soft tissue lesions, whereas 68% of evaluable patients had improvement on bone scan, including complete resolution in 12%. The objective response rate at 12 weeks was 5%, with stable disease in 75% of patients. Thirty-one patients with stable disease at week 12 were randomly assigned. Median PFS was 23.9 weeks (95% CI, 10.7 to 62.4 weeks) with cabozantinib and 5.9 weeks (95% CI, 5.4 to 6.6 weeks) with placebo (hazard ratio, 0.12; P < .001). Serum total alkaline phosphatase and plasma cross-linked C-terminal telopeptide of type I collagen were reduced by ≥ 50% in 57% of evaluable patients. On retrospective review, bone pain improved in 67% of evaluable patients, with a decrease in narcotic use in 56%. The most common grade 3 adverse events were fatigue (16%), hypertension (12%), and hand-foot syndrome (8%).. Cabozantinib has clinical activity in men with CRPC, including reduction of soft tissue lesions, improvement in PFS, resolution of bone scans, and reductions in bone turnover markers, pain, and narcotic use.

Topics: Aged; Aged, 80 and over; Alkaline Phosphatase; Anilides; Antineoplastic Agents; Biomarkers, Tumor; Bone Neoplasms; Bone Remodeling; Collagen Type I; Disease-Free Survival; Follow-Up Studies; Humans; Kaplan-Meier Estimate; Lymphatic Metastasis; Male; Middle Aged; Orchiectomy; Peptides; Prostatic Neoplasms; Pyridines; Receptor Protein-Tyrosine Kinases; Treatment Outcome

Topics: Anilides; Animals; Disease Models, Animal; Humans; Male; Mice; Nanoparticles; Neutrophils; Prostatic Neoplasms; Pyridines; Receptor Protein-Tyrosine Kinases

With the advent of potent second-line anti-androgen therapy, we and others have observed an increased incidence of androgen receptor (AR)-null small cell or neuroendocrine prostate cancer (SCNPC) in metastatic castration-resistant prostate cancer (mCRPC). Our study was designed to determine the effect of cabozantinib, a multi-targeted tyrosine kinase inhibitor that inhibits VEGFR2, MET and RET on SCNPC. Transcriptome analysis of the University of Washington rapid autopsy and SU2C mCRPC datasets revealed upregulated MET and RET expression in SCNPCs relative to adenocarcinomas. Additionally, increased MET expression correlated with attenuated AR expression and activity. In vitro treatment of SCNPC patient-derived xenograft (PDX) cells with the MET inhibitor AMG-337 had no impact on cell viability in LuCaP 93 (MET+/RET+) and LuCaP 173.1 (MET-/RET-), whereas cabozantinib decreased cell viability of LuCaP 93, but not LuCaP 173.1. Notably, MET+/RET+ LuCaP 93 and MET-/RET- LuCaP 173.1 tumor volumes were significantly decreased with cabozantinib treatment in vivo, and this activity was independent of MET or RET expression in LuCaP 173.1. Tissue analysis indicated that cabozantinib did not inhibit tumor cell proliferation (Ki67), but significantly decreased microvessel density (CD31) and increased hypoxic stress and glycolysis (HK2) in LuCaP 93 and LuCaP 173.1 tumors. RNA-Seq and gene set enrichment analysis revealed that hypoxia and glycolysis pathways were increased in cabozantinib-treated tumors relative to control tumors. Our data suggest that the most likely mechanism of cabozantinib-mediated tumor growth suppression in SCNPC PDX models is through disruption of the tumor vasculature. Thus, cabozantinib may represent a potential therapy for patients with metastatic disease in tumor phenotypes that have a significant dependence on the tumor vasculature for survival and proliferation.

Topics: Anilides; Animals; Carcinoma, Neuroendocrine; Cell Line, Tumor; Humans; Male; Mice; Mice, SCID; Neovascularization, Pathologic; Prostatic Neoplasms; Proto-Oncogene Proteins c-met; Proto-Oncogene Proteins c-ret; Pyridines; Xenograft Model Antitumor Assays

Topics: Anilides; Gallium Isotopes; Gallium Radioisotopes; Humans; Male; Membrane Glycoproteins; Middle Aged; Organometallic Compounds; Positron Emission Tomography Computed Tomography; Prostate-Specific Antigen; Prostatic Neoplasms; Pyridines

Topics: Anilides; Animals; Antineoplastic Agents; Cell Line, Tumor; Docetaxel; Drug Administration Schedule; Drug Synergism; Humans; Male; Mice; Mice, Nude; Prostatic Neoplasms; Pyridines; Taxoids

Prostate cancer characteristically induces osteoblastic bone metastasis, for which no therapies are available. A dual kinase inhibitor of c-Met and VEGFR-2 (cabozantinib) was shown to reduce prostate cancer growth in bone, with evidence for suppressing osteoblastic activity. However, c-Met and VEGFR2 signaling in osteoblasts in the context of bone metastasis remain unclear. Here we show using cultured osteoblasts that hepatocyte growth factor (HGF) and VEGF-A increased receptor activator of NFκB ligand (RANKL) and M-CSF, two essential factors for osteoclastogenesis. Insulin-like growth factor-1 (IGF1) also increased RANKL and M-CSF via c-Met transactivation. The conditioned media from IGF1-, HGF-, or VEGFA-treated osteoblasts promoted osteoclastogenesis that was reversed by inhibiting c-Met and/or VEGFR2 in osteoblasts. In vivo experiments used cabozantinib-resistant prostate cancer cells (PC-3 and C4-2B) to test the effects of c-Met/VEGFR2 inhibition specifically in osteoblasts. Cabozantinib (60 mg/kg, 3 weeks) suppressed tumor growth in bone and reduced expression of RANKL and M-CSF and subsequent tumor-induced osteolysis. Collectively, inhibition of c-Met and VEGFR2 in osteoblasts reduced RANKL and M-CSF expression, and associated with reduction of tumor-induced osteolysis, suggesting that c-Met and VEGFR2 are promising therapeutic targets in bone metastasis.

Topics: Anilides; Animals; Bone Neoplasms; Cell Line; Cell Line, Tumor; Cell Proliferation; Cells, Cultured; Humans; Male; Mice, Nude; Osteoblasts; Osteolysis; Prostatic Neoplasms; Proto-Oncogene Proteins c-met; Pyridines; RNA Interference; Vascular Endothelial Growth Factor Receptor-2; Xenograft Model Antitumor Assays

Cabozantinib is an oral multiple tyrosine kinase receptor inhibitor (ITK): VEGFR2, c-MET and RET. Inhibition of VEGFR and c-MET decrease resistance of VEGFR inhibitor via c-MET axis. Cabozantinib improve progression-free survival (PFS) in progressive metastatic medullary thyroid cancer (MTC): 4 months in the placebo group and 11.2 months in the cabozantinib group (P<0.001) in all patient subgroups including those with or without prior ITK and RET mutation status. Cabozantinib increased overall survival (OS) compared with everolimus in patients with advanced renal cell carcinoma who progressed after previous VEGFR ITK treatment: 21.4 months in cabozantinib group and 16.5 months in everolimus group (P<0.0003). Cabozantinib obtained the AMM for the treatment of progressive metastatic MTC and advanced renal cell carcinoma. Cabozantinib is a new option in the treatment of MTC by inclusion in therapeutic trials (no payment in this indication) and advanced renal cell carcinoma (hospital delivery). Its tolerance is similar to anti-angiogenic therapies and justifies an optimal management of the secondary effect.

Topics: Anilides; Antineoplastic Agents; Bone Neoplasms; Carcinoma, Neuroendocrine; Carcinoma, Non-Small-Cell Lung; Carcinoma, Renal Cell; Clinical Trials as Topic; Disease-Free Survival; Everolimus; Humans; Kidney Neoplasms; Lung Neoplasms; Male; Piperidines; Prostatic Neoplasms; Proto-Oncogene Proteins c-ret; Pyridines; Quinazolines; Receptor Protein-Tyrosine Kinases; Thyroid Neoplasms; Vascular Endothelial Growth Factor Receptor-2

Several kinase inhibitors that target aberrant signaling pathways in tumor cells have been deployed in cancer therapy. However, their impact on the tumor immune microenvironment remains poorly understood. The tyrosine kinase inhibitor cabozantinib showed striking responses in cancer clinical trial patients across several malignancies. Here, we show that cabozantinib rapidly eradicates invasive, poorly differentiated PTEN/p53-deficient murine prostate cancer. This was associated with enhanced release of neutrophil chemotactic factors from tumor cells, including CXCL12 and HMGB1, resulting in robust infiltration of neutrophils into the tumor. Critically, cabozantinib-induced tumor clearance in mice was abolished by antibody-mediated granulocyte depletion or HMGB1 neutralization or blockade of neutrophil chemotaxis with the CXCR4 inhibitor plerixafor. Collectively, these data demonstrate that cabozantinib triggers a neutrophil-mediated anticancer innate immune response, resulting in tumor clearance.

Topics: Anilides; Animals; Benzylamines; Cell Line, Tumor; Cell Proliferation; Chemokine CXCL12; Cyclams; Heterocyclic Compounds; HMGB1 Protein; Humans; Immunity, Innate; Male; Mice; Neutrophils; Prostatic Neoplasms; Protein Kinase Inhibitors; PTEN Phosphohydrolase; Pyridines; Tumor Microenvironment; Tumor Suppressor Protein p53

We performed parallel investigations in cabozantinib-treated patients in a phase II trial and simultaneously in patient-derived xenograft (PDX) models to better understand the roles of MET and VEGFR2 as targets for prostate cancer therapy.. In the clinical trial, radiographic imaging and serum markers were examined, as well as molecular markers in tumors from bone biopsies. In mice harboring PDX intrafemurally or subcutaneously, cabozantinib effects on tumor growth, MET, PDX in which MET was silenced, VEGFR2, bone turnover, angiogenesis, and resistance were examined.. In responsive patients and PDX, islets of viable pMET-positive tumor cells persisted, which rapidly regrew after drug withdrawal. Knockdown of MET in PDX did not affect tumor growth in mice nor did it affect cabozantinib-induced growth inhibition but did lead to induction of FGFR1. Inhibition of VEGFR2 and MET in endothelial cells reduced the vasculature, leading to necrosis. However, each islet of viable cells surrounded a VEGFR2-negative vessel. Reduction of bone turnover was observed in both cohorts.. Our studies demonstrate that MET in tumor cells is not a persistent therapeutic target for metastatic castrate-resistant prostate cancer (CRPC), but inhibition of VEGFR2 and MET in endothelial cells and direct effects on osteoblasts are responsible for cabozantinib-induced tumor inhibition. However, vascular heterogeneity represents one source of primary therapy resistance, whereas induction of FGFR1 in tumor cells suggests a potential mechanism of acquired resistance. Thus, integrated cross-species investigations demonstrate the power of combining preclinical models with clinical trials to understand mechanisms of activity and resistance of investigational agents.

Topics: Anilides; Animals; Antineoplastic Agents; Apoptosis; Bone Neoplasms; Cell Line, Tumor; Clinical Trials, Phase II as Topic; Disease Models, Animal; Drug Resistance, Neoplasm; Gene Knockdown Techniques; Humans; Male; Mice; Multicenter Studies as Topic; Neoplasm Staging; Phosphorylation; Positron-Emission Tomography; Prostatic Neoplasms; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-met; Pyridines; Receptor, Fibroblast Growth Factor, Type 1; Signal Transduction; Treatment Outcome; Tumor Burden; Vascular Endothelial Growth Factor Receptor-2; Xenograft Model Antitumor Assays

Abiraterone improves the overall survival of men with metastatic castration-resistant prostate cancer. However, de novo or adaptive resistance to abiraterone limits its activity. Rational combinations of drugs with different mechanisms of action that overcome resistance mechanisms may improve the efficacy of therapy. To that end, we studied the molecular and phenotypic effects of the combination of cabozantinib plus abiraterone.. Three prostate cancer cell lines were used to interrogate the in vitro molecular and antiproliferative effects of the single agents and combination of cabozantinib and abiraterone. The in vivo impact of the combination was assessed using the LAPC4-CR xenograft mouse model.. In vitro proliferation studies demonstrated single-agent doses between 2 μmol/L and 10 μmol/L for abiraterone and cabozantinib inhibit prostate cancer cell proliferation in a dose-dependent manner, and the anticancer activity of abiraterone is enhanced when combined with cabozantinib. In vivo LAPC4-CR xenograft mouse studies also showed that cabozantinib can improve the antitumor activity of abiraterone. Cabozantinib, a multiple receptor tyrosine kinase inhibitor, enhances the ability of abiraterone to inhibit AR activity in a cell line-dependent manner. In addition, our cell line studies demonstrate abiraterone-stimulated insulin-like growth factor I receptor (IGFIR) phosphorylation with downstream activation of MEK1/2 and ERK1/2, and that this potential adaptive resistance mechanism was inhibited by cabozantinib.. Cabozantinib can enhance the efficacy of abiraterone by blocking multiple compensatory survival mechanisms, including IGFIR activation, and supports the assessment of the combination in a clinical trial.

Topics: Androstenes; Anilides; Animals; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Drug Antagonism; Drug Resistance, Neoplasm; Humans; Male; Mice; Phosphorylation; Prostatic Neoplasms; Pyridines; Receptor Protein-Tyrosine Kinases; Receptor, IGF Type 1; Receptors, Androgen; Signal Transduction; Tumor Burden; Xenograft Model Antitumor Assays

Resistance to currently available targeted therapies significantly hampers the survival of patients with prostate cancer with bone metastasis. Here we demonstrate an important resistance mechanism initiated from tumor-induced bone. Studies using an osteogenic patient-derived xenograft, MDA-PCa-118b, revealed that tumor cells resistant to cabozantinib, a Met and VEGFR-2 inhibitor, reside in a "resistance niche" adjacent to prostate cancer-induced bone. We performed secretome analysis of the conditioned medium from tumor-induced bone to identify proteins (termed "osteocrines") found within this resistance niche. In accordance with previous reports demonstrating that activation of integrin signaling pathways confers therapeutic resistance, 27 of the 90 osteocrines identified were integrin ligands. We found that following cabozantinib treatment, only tumor cells positioned adjacent to the newly formed woven bone remained viable and expressed high levels of pFAK-Y397 and pTalin-S425, mediators of integrin signaling. Accordingly, treatment of C4-2B4 cells with integrin ligands resulted in increased pFAK-Y397 expression and cell survival, whereas targeting integrins with FAK inhibitors PF-562271 or defactinib inhibited FAK phosphorylation and reduced the survival of PC3-mm2 cells. Moreover, treatment of MDA-PCa-118b tumors with PF-562271 led to decreased tumor growth, irrespective of initial tumor size. Finally, we show that upon treatment cessation, the combination of PF-562271 and cabozantinib delayed tumor recurrence in contrast to cabozantinib treatment alone. Our studies suggest that identifying paracrine de novo resistance mechanisms may significantly contribute to the generation of a broader set of potent therapeutic tools that act combinatorially to inhibit metastatic prostate cancer.

Topics: Anilides; Animals; Antineoplastic Agents; Bone and Bones; Cell Line, Tumor; Cell Proliferation; Drug Resistance, Neoplasm; Humans; Immunohistochemistry; Male; Mice; Ossification, Heterotopic; Prostatic Neoplasms; Pyridines; Reverse Transcriptase Polymerase Chain Reaction; Xenograft Model Antitumor Assays

Cabozantinib, an orally available multityrosine kinase inhibitor with activity against mesenchymal epithelial transition factor (MET) and VEGF receptor 2 (VEGFR2), induces resolution of bone scan lesions in men with castration-resistant prostate cancer bone metastases. The purpose of this study was to determine whether cabozantinib elicited a direct antitumor effect, an indirect effect through modulating bone, or both.. Using human prostate cancer xenograft studies in mice, we determined the impact of cabozantinib on tumor growth in soft tissue and bone. In vitro studies with cabozantinib were performed using (i) prostate cancer cell lines to evaluate its impact on cell growth, invasive ability, and MET and (ii) osteoblast cell lines to evaluate its impact on viability and differentiation and VEGFR2.. Cabozantinib inhibited progression of multiple prostate cancer cell lines (Ace-1, C4-2B, and LuCaP 35) in bone metastatic and soft tissue murine models of prostate cancer, except for PC-3 prostate cancer cells in which it inhibited only subcutaneous growth. Cabozantinib directly inhibited prostate cancer cell viability and induced apoptosis in vitro and in vivo and inhibited cell invasion in vitro. Cabozantinib had a dose-dependent biphasic effect on osteoblast activity and inhibitory effect on osteoclast production in vitro that was reflected in vivo. It blocked MET and VEGFR2 phosphorylation in prostate cancer cells and osteoblast-like cells, respectively.. These data indicate that cabozantinib has direct antitumor activity, and that its ability to modulate osteoblast activity may contribute to its antitumor efficacy.

Topics: Anilides; Animals; Antineoplastic Agents; Bone Neoplasms; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Humans; Immunoblotting; Immunohistochemistry; Male; Mice; Mice, SCID; Osteoblasts; Prostatic Neoplasms; Pyridines; Xenograft Model Antitumor Assays

Treatment with cabozantinib, an inhibitor of MET and VEGFR2 signaling, has demonstrated clinical benefit in early trials in men with metastatic prostate cancer. Preclinical evidence suggests that cabozantinib can kill cancer cell seeds while disrupting angiogenesis and stromal cells in the metastatic soil.

Topics: Anilides; Animals; Antineoplastic Agents; Bone Neoplasms; Cell Proliferation; Humans; Male; Osteoblasts; Prostatic Neoplasms; Pyridines

Cabozantinib is an oral MET/VEGFR2 inhibitor. A recent phase II study of cabozantinib (100 mg daily) showed improved bone scans in subjects with metastatic castration-resistant prostate cancer (mCRPC), but adverse events (AE) caused frequent dose reductions. This study was designed to determine the efficacy and tolerability of cabozantinib at lower starting doses.. An adaptive design was used to determine the lowest active daily dose among 60, 40, and 20 mg. The primary endpoint was week 6 bone scan response, defined as ≥30% decrease in bone scan lesion area. The secondary endpoint was change in circulating tumor cells (CTC).. Among 11 evaluable subjects enrolled at 40 mg, there were 9 partial responses (PR), 1 complete response, and 1 stable disease (SD). Of 10 subjects subsequently enrolled at 20 mg, there were 1 PR, 5 SDs, and 4 with progressive disease. Among 13 subjects enrolled on the 40 mg expansion cohort, there were 6 PRs and 7 SDs. No subjects required dose reduction or treatment interruption at 6 or 12 weeks; 3 subjects at dose level 0 discontinued due to AEs by 12 weeks. At 40 mg, median treatment duration was 27 weeks. 58% of subjects with ≥5 CTCs/7.5 mL at baseline converted to <5.. Cabozantinib 40 mg daily was associated with a high rate of bone scan response. Cabozantinib 40 mg daily was associated with better tolerability than previously reported for cabozantinib 100 mg daily. These observations informed the design of phase III studies of cabozantinib in mCRPC.

Topics: Aged; Aged, 80 and over; Anilides; Antineoplastic Agents; Bone Neoplasms; Cohort Studies; Humans; Male; Middle Aged; Neoplastic Cells, Circulating; Orchiectomy; Prostate-Specific Antigen; Prostatic Neoplasms; Protein Kinase Inhibitors; Pyridines; Treatment Outcome

Topics: Anilides; Antineoplastic Agents; Bone Neoplasms; Humans; Male; Prostatic Neoplasms; Pyridines; Receptor Protein-Tyrosine Kinases

The development and evaluation of a computer-aided bone scan analysis technique to quantify changes in tumor burden and assess treatment effects in prostate cancer clinical trials.. We have developed and report on a commercial fully automated computer-aided detection (CAD) system. Using this system, scan images were intensity normalized, and then lesions were identified and segmented by anatomic region-specific intensity thresholding. Detected lesions were compared against expert markings to assess the accuracy of the CAD system. The metrics Bone Scan Lesion Area, Bone Scan Lesion Intensity, and Bone Scan Lesion Count were calculated from identified lesions, and their utility in assessing treatment effects was evaluated by analyzing before and after scans from metastatic castration-resistant prostate cancer patients: 10 treated and 10 untreated. In this study, patients were treated with cabozantinib, a MET/vascular endothelial growth factor inhibitor resulting in high rates of resolution of bone scan abnormalities.. Our automated CAD system identified bone lesion pixels with 94% sensitivity, 89% specificity, and 89% accuracy. Significant differences in changes from baseline were found between treated and untreated groups in all assessed measurements derived by our system. The most significant measure, Bone Scan Lesion Area, showed a median (interquartile range) change from baseline at week 6 of 7.13% (27.61) in the untreated group compared with -73.76% (45.38) in the cabozantinib-treated group (P=0.0003).. Our system accurately and objectively identified and quantified metastases in bone scans, allowing for interpatient and intrapatient comparison. It demonstrates potential as an objective measurement of treatment effects, laying the foundation for validation against other clinically relevant outcome measures.

Topics: Anilides; Bone Neoplasms; Humans; Image Processing, Computer-Assisted; Male; Prostatic Neoplasms; Pyridines; Radionuclide Imaging; Radiopharmaceuticals; Sensitivity and Specificity; Technetium Tc 99m Medronate; Treatment Outcome; Tumor Burden; Whole Body Imaging