Safety and efficacy of sorafenib in patients with castrate resistant prostate cancer: a Phase II study

Sorafenib Encapsulated Poly(ester amide) Nanoparticles for Efficient and Biosafe Prostate Cancer Therapy

Prostate cancer (PCa) with a high incidence worldwide is a serious threat to men's health. Despite the continuous development of treatment strategies for PCa in recent years, the long-term prognosis of patients is still poor. Hence, the discovery and development of novel, secure, and efficient therapeutic approaches hold significant clinical significance. Although sorafenib (SOR) displays potential as a therapeutic option for PCa, its clinical efficacy is hindered by drug resistance, limited water solubility, and rapid metabolism. Therefore, we proposed to prepare nanoparticles (named SOR@8P4 NPs) utilizing the phenylalanine-based poly(ester amide) polymer (8P4) as the drug carrier to enhance the solubility and drug stability of SOR and improve the therapeutic targeting and bioavailability. SOR@8P4 NPs had high stability and showed acid-responsive drug release at the acidic tumor microenvironment. Additionally, SOR@8P4 NPs demonstrated more remarkable anticancer, antimetastatic, and antiproliferative abilities in vitro, compared with those of free drugs. SOR@8P4 NPs showed high tumor targeting and significantly inhibited tumor growth in vivo. In summary, the drug delivery system of SOR@8P4 NPs provides new ideas for the clinical treatment of PCa.

Combinatorial approaches of nanotherapeutics for inflammatory pathway targeted therapy of prostate cancer

Prostate cancer (PC) is the most prevalent male urogenital cancer worldwide. PC patients presenting an advanced or metastatic cancer succumb to the disease, even after therapeutic interventions including radiotherapy, surgery, androgen deprivation therapy (ADT), and chemotherapy. One of the hallmarks of PC is evading immune surveillance and chronic inflammation, which is a major challenge towards designing effective therapeutic formulations against PC. Chronic inflammation in PC is often characterized by tumor microenvironment alterations, epithelial-mesenchymal transition and extracellular matrix modifications. The inflammatory events are modulated by reactive nitrogen and oxygen species, inflammatory cytokines and chemokines. Major signaling pathways in PC includes androgen receptor, PI3K and NF-κB pathways and targeting these inter-linked pathways poses a major therapeutic challenge. Notably, many conventional treatments are clinically unsuccessful, due to lack of targetability and poor bioavailability of the therapeutics, untoward toxicity and multidrug resistance. The past decade witnessed an advancement of nanotechnology as an excellent therapeutic paradigm for PC therapy. Modern nanovectorization strategies such as stimuli-responsive and active PC targeting carriers offer controlled release patterns and superior anti-cancer effects. The current review initially describes the classification, inflammatory triggers and major inflammatory pathways of PC, various PC treatment strategies and their limitations. Subsequently, recent advancement in combinatorial nanotherapeutic approaches, which target PC inflammatory pathways, and the mechanism of action are discussed. Besides, the current clinical status and prospects of PC homing nanovectorization, and major challenges to be addressed towards the advancement PC therapy are also addressed.

Synergistic Effects of Nobiletin and Sorafenib Combination on Metastatic Prostate Cancer Cells

Objective: Herein we, for the first time, investigated a potential synergistic effect of nobiletin (NOB) and sorafenib (SOR) on PC-3 prostate cancer and HUVEC control cell lines. Methods: In order to determine the cytotoxic and apoptotic effects of the combination of NOB and SOR, WST-1, Annexin V, and cell cycle analysis were performed. The potential molecular mechanism of apoptotic cell death was assessed by Bax, Bcl-2, CCDN1, Rb1, and CDKN1A gene expression and acridine orange (AO) and DAPI staining. Results: Our results indicated that NOB and SOR combination had a significant inhibitory effect on the viability of PC-3 cells with less toxicity on HUVEC cells than SOR alone (P < 0.01). NOB and SOR combination significantly caused much more apoptotic cell death and cell cycle arrest at G0/G1 phase by up-regulation of Bax, Rb1, and CDKN1A levels in PC-3 cells (P < 0.01). Therefore, strong synergistic effects between NOB and SOR were analyzed (CI < 1). Conclusion: NOB and SOR combination was more effective than SOR and NOB alone and reduced the exposure time for SOR and NOB in PC-3 cells. Combination strategy is a therapeutic potential to improve efficacy and reduce side-effect of SOR for the treatment of metastatic prostate cancer cells.

Targeting androgen-independent pathways: new chances for patients with prostate cancer?

Androgen deprivation therapy (ADT) is the mainstay treatment for advanced prostate cancer (PC). Most patients eventually progress to a condition known as castration-resistant prostate cancer (CRPC), characterized by lack of response to ADT. Although new androgen receptor signaling (ARS) inhibitors and chemotherapeutic agents have been introduced to overcome resistance to ADT, many patients progress because of primary or acquired resistance to these agents. This comprehensive review aims at exploring the mechanisms of resistance and progression of PC, with specific focus on alterations which lead to the activation of androgen receptor (AR)-independent pathways of survival. Our work integrates available clinical and preclinical data on agents which target these pathways, assessing their potential clinical implication in specific settings of patients. Given the rising interest of the scientific community in cancer immunotherapy strategies, further attention is dedicated to the role of immune evasion in PC.

Inefficiencies and Patient Burdens in the Development of the Targeted Cancer Drug Sorafenib: A Systematic Review

Failure in cancer drug development exacts heavy burdens on patients and research systems. To investigate inefficiencies and burdens in targeted drug development in cancer, we conducted a systematic review of all prelicensure trials for the anticancer drug, sorafenib (Bayer/Onyx Pharmaceuticals). We searched Embase and MEDLINE databases on October 14, 2014, for prelicensure clinical trials testing sorafenib against cancers. We measured risk by serious adverse event rates, benefit by objective response rates and survival, and trial success by prespecified primary endpoint attainment with acceptable toxicity. The first two clinically useful applications of sorafenib were discovered in the first 2 efficacy trials, after five drug-related deaths (4.6% of 108 total) and 93 total patient-years of involvement (2.4% of 3,928 total). Thereafter, sorafenib was tested in 26 indications and 67 drug combinations, leading to one additional licensure. Drug developers tested 5 indications in over 5 trials each, comprising 56 drug-related deaths (51.8% of 108 total) and 1,155 patient-years (29.4% of 3,928 total) of burden in unsuccessful attempts to discover utility against these malignancies. Overall, 32 Phase II trials (26% of Phase II activity) were duplicative, lacked appropriate follow-up, or were uninformative because of accrual failure, constituting 1,773 patients (15.6% of 11,355 total) participating in prelicensure sorafenib trials. The clinical utility of sorafenib was established early in development, with low burden on patients and resources. However, these early successes were followed by rapid and exhaustive testing against various malignancies and combination regimens, leading to excess patient burden. Our evaluation of sorafenib development suggests many opportunities for reducing costs and unnecessary patient burden in cancer drug development.

Targeting neuroendocrine prostate cancer: molecular and clinical perspectives

Neuroendocrine prostate carcinoma, either co-present with the local adenocarcinoma disease or as a result of transdifferentiation later in time, was described as one major process of emerging resistance to androgen deprivation therapies, and at the clinical level it is consistent with the development of rapidly progressive visceral disease, often in the absence of elevated serum prostate-specific antigen level. Until present, platinum-based chemotherapy has been the only treatment modality, able to produce a fair amount of responses but of short duration. Recently, several efforts for molecular characterization of this lethal phenotype have resulted in identification of novel signaling factors involved in microenvironment interactions, mitosis, and neural reprograming as potential therapeutic targets. Ongoing clinical testing of specific inhibitors of these targets, for example, Aurora kinase A inhibitors, in carefully selected patients and exploitation of expression changes of the target before and after manipulation is anticipated to increase the existing data and facilitate therapeutic decision making at this late stage of the disease when hormonal manipulations, even with the newest androgen-directed therapies are no longer feasible.

Incidence and risk of sorafenib-induced hypertension: a systematic review and meta-analysis

Hypertension is one of the major side effects of sorafenib, and reported incidences vary substantially among clinical trials. A systematic review was conducted using Medline, PubMed, Embase, and the Cochrane Library for all longitudinal studies to investigate the incidence and risk of hypertension events in cancer patients treated with sorafenib. A total of 14 randomized controlled trials and 39 prospective single-arm trials involving 13,555 patients were selected for the meta-analysis. The relative risk of all-grade and high-grade hypertension associated with sorafenib were 3.07 (95% confidence interval [CI], 2.05–4.60; P<.01) and 3.31 (95% CI, 2.21–4.95; P<.01), respectively. The overall incidence of sorafenib-induced all-grade and high-grade hypertension were 19.1% (95% CI, 15.8%–22.4%) and 4.3% (95% CI, 3.0%–5.5%), respectively. A significantly higher incidence of hypertension was noted in patients with renal cell carcinoma (RCC) compared with those with non-RCC malignancies (all-grade: 24.9% [95% CI, 19.7%–30.1%] vs 15.7%[95% CI, 12.1%–19.3%]; P<.05; high-grade:8.6% [95% CI, 6.0%–11.2%] vs 1.8% [95% CI, 0.9%–2.6%]; P<.05). The trials with median progression-free survival (PFS) longer than 5.3 months (mean PFS) demonstrated a significantly higher incidence of high-grade hypertension than trials with shorter PFS (6.3% [95% CI, 4.1%–8.5%] vs 2.6% [95% CI, 1.4%– 3.8%]; P<.05). Findings of the meta-analysis indicated a significantly high risk of sorafenib-induced hypertension. Patients with RCC have a significantly higher incidence of hypertension and the occurrence of hypertension may be associated with improved prognosis.

Oral anticancer drugs: how limited dosing options and dose reductions may affect outcomes in comparative trials and efficacy in patients

Historically, cancer medicine has avoided the problem of unequal dosing by comparing maximum-tolerated doses of intravenous regimens with proportionate dose reductions for toxicity. However, in recent years, with the development of numerous oral anticancer agents, dosing options are arbitrarily and increasingly limited by the size of pills. We contend that an underappreciated consequence of pill size is unequal dosing in comparative clinical trials and that this can have an impact on outcomes. We discuss how comparative effectiveness trials can be unbalanced and how the use of doses that are not sustainable might affect outcomes, especially marginal ones. We further argue that because of their poor tolerability and their limited dosing options, which often result in large dose adjustments in response to toxicity, the real-world clinical effectiveness of oral anticancer agents may be diminished and may not emulate results achieved in registration trials.

Sorafenib: targeting multiple tyrosine kinases in cancer

Sorafenib (BAY 43-9006, Nexavar®) is an oral multiple tyrosine kinase inhibitor. Main targets are receptor tyrosine kinase pathways frequently deregulated in cancer such as the Raf-Ras pathway, vascular endothelial growth factor (VEGF) pathway, and FMS-like tyrosine kinase 3 (FLT3). Sorafenib was approved by the FDA in fast track for advanced renal cell cancer and hepatocellular cancer and shows good clinical activity in thyroid cancer. Multiple clinical trials are undertaken to further investigate the role of sorafenib alone or in combination for the treatment of various tumor entities.

Role of sorafenib in overcoming resistance of chemotherapy-failure castration-resistant prostate cancer

BACKGROUND

Sorafenib promotes apoptosis through downstream pathways that can be deregulated in CRPC. We hypothesized that sorafenib could overcome chemotherapy resistance in CRPC.

PATIENTS AND METHODS

Eligible patients were those whose disease had progressed during chemotherapy (docetaxel or mitoxantrone) or within 12 weeks of stopping either. Patients then continued or resumed their last chemotherapy regimen with the addition of sorafenib 400 mg twice daily. Patients received a maximum of 6 cycles of chemotherapy/sorafenib followed by sorafenib alone until disease progression. The primary end point was combination safety. Secondary end points were overall response, percentage of SD, and time to progression (TTP).

RESULTS

Twenty-two patients (21 evaluable) were enrolled (16 patients with Gleason score ≥ 7). Median age was 68 years (range, 59-83 years). Median prostate-specific antigen (PSA) was 142 ng/dL (range, 13.6-9584). Visceral and bone disease were present combined in 9 patients (41%). Ten patients (47.6%) showed biochemical response (19% with > 50% PSA decline) and 16 patients (76%) achieved radiographic stability (according to Response Evaluation Criteria for Solid Tumors) after starting sorafenib for a median duration of 6 months (range, 4-12 months). Grade 3/4 nonhematologic toxicities were fatigue (n = 7, 32%), palmar-plantar erythrodysesthesia (n = 4, 18%). Dose reduction of sorafenib occurred at least once in 15 patients (68%) because of palmar-plantar erythrodysesthesia (22%) and fatigue (22%). With a median follow-up of 19 months (range, 3-46 months), median overall survival was 8 months. TTP according to PSA level was 3 months and TTP according to imaging studies and/or clinically was 6 months. Median number of treatment cycles given was 6 (range, 1-10).

CONCLUSION

Sorafenib can be combined safely with chemotherapy and in some patients overcomes chemotherapy resistance.

Pruritus in patients treated with targeted cancer therapies: systematic review and meta-analysis

BACKGROUND

Pruritus has been anecdotally described in association with targeted cancer therapies. The risk of pruritus has not been systematically ascertained.

OBJECTIVE

A systematic review and meta-analysis of the literature was conducted for axitinib, cetuximab, dasatinib, erlotinib, everolimus, gefitinib, imatinib, ipilimumab, lapatinib, nilotinib, panitumumab, pazopanib, rituximab, sorafenib, temsirolimus, tositumomab, vandetanib, and vemurafenib.

METHODS

Databases from PubMed, Web of Science (January 1998 through July 2012), and American Society of Clinical Oncology abstracts (2004 through 2012) were searched. Incidence and relative risk of pruritus were calculated using random- or fixed-effects model.

RESULTS

The incidences of all-grade and high-grade pruritus were 17.4% (95% confidence interval 16.0%-19.0%) and 1.4% (95% confidence interval 1.2%-1.6%), respectively. There was an increased risk of all-grade pruritus (relative risk 2.90 [95% confidence interval 1.76-4.77, P < .001]) and variation among different drugs (P < .001).

LIMITATIONS

The reporting of pruritus may vary, resulting from concomitant medications, comorbidities, and underlying malignancies. We found a higher incidence of pruritus in patients with solid tumors, concordant with those targeted therapies with the highest pruritus incidences.

CONCLUSION

There is a significant risk of developing pruritus in patients receiving targeted therapies. To prevent suboptimal dosing and decreased quality of life, patients should be counseled and treated against this untoward symptom.

Effects of sorafenib on C-terminally truncated androgen receptor variants in human prostate cancer cells

Recent evidence suggests that the development of castration resistant prostate cancer (CRPCa) is commonly associated with an aberrant, ligand-independent activation of the androgen receptor (AR). A putative mechanism allowing prostate cancer (PCa) cells to grow under low levels of androgens, is the expression of constitutively active, C-terminally truncated AR lacking the AR-ligand binding domain (LBD). Due to the absence of a LBD, these receptors, termed ARΔLBD, are unable to respond to any form of anti-hormonal therapies. In this study we demonstrate that the multikinase inhibitor sorafenib inhibits AR as well as ARΔLBD-signalling in CRPCa cells. This inhibition was paralleled by proteasomal degradation of the AR- and ARΔLBD-molecules. In line with these observations, maximal antiproliferative effects of sorafenib were achieved in AR and ARΔLBD-positive PCa cells. The present findings warrant further investigations on sorafenib as an option for the treatment of advanced AR-positive PCa.

Phase I study investigating the safety and feasibility of combining imatinib mesylate (Gleevec) with sorafenib in patients with refractory castration-resistant prostate cancer

Background:

Determining the maximum tolerated dose (MTD) and the dose-limiting toxicity (DLT) of sorafenib (S) plus imatinib (IM) in castration-resistant prostate cancer (CRPC) patients.

Methods:

Refractory CRPC patients were enrolled onto this 3+3 dose escalation designed study. Imatinib pharmacokinetics (PK) were determined on day 15, 4 h post dose with a validated LC–MS assay.

Results:

Seventeen patients were enrolled; 10 evaluable (6 at 400 mg S qd with 300 mg IM qd (DL0) and 4 at 400 mg S bid with 300 mg IM qd (DL1)); inevaluable patients received <1 cycle. The median age was 73 (57–89); median prostatic serum antigen was 284 ng ml⁻¹ (11.7–9027). Median number of prior non-hormonal therapies was 3 (1–12). Dose-limiting toxicities were diarrhoea and hand-foot syndrome. Maximum tolerated dose was 400 mg S and 300 mg IM both daily. No biochemical responses were observed. Two patients had stable disease by RECIST. Median time to progression was 2 months (1–5). Median OS was 6 months (1–30+) with 3/17 patients (17%) alive at 21 months median follow-up. Ten patients had PK data suggesting that S reduced IM clearance by 55%, resulting in 77% increased exposure (P=0.005; compared with historical data).

Conclusion:

This is the first report showing that S+IM can be administered in CRPC at a dose of 400 mg S and 300 mg IM, daily.

Sorafenib in progressive castrate-resistant prostate cancer. Can we talk about a new therapeutic option?

Castrate-resistant prostate cancer represents a significant clinical challenge. Currently, the standard treatment for patients with castrate-resistant prostate cancer is chemotherapy, after which patients only receive symptomatic treatment. The available results of phase II clinical trials of sorafenib in patients with hormone-refractory prostate cancer indicate that, despite a relatively short progression-free survival, the treatment may be associated with good outcomes in terms of overall survival and maintenance of a good quality of life. The study presents the authors' critical opinions and observations about the usefulness of sorafenib in patients with prostate cancer.

Perfusion MRI for monitoring the effect of sorafenib on experimental prostate carcinoma: a validation study

OBJECTIVE

The purpose of this study was to investigate with immunohistochemical validation whether dynamic contrast-enhanced MRI with small-molecule contrast medium is useful for monitoring the effects of the multikinase inhibitor sorafenib on prostate carcinomas in rats.

MATERIALS AND METHODS

Copenhagen rats (n = 20) into which prostate carcinoma (MAT-Ly-Lu-B2) had been implanted subcutaneously were imaged on the day of implantation and 7 days later with 3-T dynamic gadobutrol-enhanced MRI. The therapy group (n = 10) received daily administration of 10 mg/kg body weight sorafenib. Quantitative measurements of tumor perfusion, tumor vascularity, and permeability-surface area product were calculated with a two-compartment model. Dynamic contrast-enhanced MRI values were correlated with immunohistochemical results for validation.

RESULTS

Tumor perfusion in sorafenib-treated prostate carcinoma declined significantly from day 0 to day 7 (47.9 ± 36.8 mL/100 mL/min to 24.4 ± 18.6 mL/100 mL/min; p < 0.05). No significant effect on permeability-surface area product was observed in either the therapy or the control group (p > 0.05). Tumor vascularity decreased significantly (p < 0.05) from day 0 to day 7 under sorafenib treatment (15.6% ± 11.4% to 5.4% ± 2.1%). Immunohistochemical analysis revealed significantly lower tumor vascularity in the therapy than in the control group (rat endothelial cell antigen 1, 74.4 ± 16.9 cells vs 197 ± 75.4 cells; p < 0.05). In sorafenib-treated tumors, significantly more apoptotic cells (terminal deoxynucleotidyl transferase-mediated nick end labeling, 6923 ± 3761 vs 3167 ± 1500; p < 0.05) and significantly fewer proliferating cells (Ki-67, 10,198 ± 3064 vs 15,003 ± 3674; p < 0.05) were observed than in the control group. Modest but significant correlations were observed between tumor perfusion and immunohistochemical tumor cell apoptosis (r = -0.56; p < 0.05) and between tumor perfusion and immunohistochemical tumor vascularity (r = 0.56; p < 0.05).

CONCLUSION

Tumor perfusion quantified with gadobutrol-enhanced dynamic contrast-enhanced MRI can be used as a noninvasive surrogate parameter for monitoring the antiangiogenic, antiproliferative, and proapoptotic effects of sorafenib on prostate carcinoma allografts as validated with immunohistochemical analysis.

Sorafenib sensitizes (-)-gossypol-induced growth suppression in androgen-independent prostate cancer cells via Mcl-1 inhibition and Bak activation

The natural BH3-mimetic (-)-gossypol shows promising efficacy in ongoing phase II/III clinical trials for human prostate cancer. Here, we show for the first time, that treatment with (-)-gossypol and multikinase inhibitor sorafenib synergistically suppresses the growth of androgen-independent prostate cancer cells (AI-PC) in vitro and in vivo. Our data suggest that sorafenib attenuates (-)-gossypol-induced Mcl-1 upregulation in AI-PCs. In this way, it serves as a potent chemosensitizer to affect cell death. Interestingly, (-)-gossypol and sorafenib induce cell death via two distinct pathways among different AI-PCs; DU145 cells via apoptosis and PC-3 via autophagy. The appointed death pathway may depend on the level of proapoptotic protein Bak, although the level of antiapoptotic protein Bcl-2 plays some role in it. DU145 cells with high Bak level prefer apoptosis induction, whereas PC-3 cells with low Bak prefer the induction of autophagy. Furthermore, inhibiting nondominant death pathways, that is, autophagy in DU145 and apoptosis in PC-3, enhances cell killing by (-)-gossypol/sorafenib combination therapy. Ultimately, our data expose a new action for sorafenib as an enhancer of (-)-gossypol-induced cell growth suppression and reveal a novel cell death mode by Bak activation manners in AI-PCs. These new insights may facilitate the rational design of clinical trials by selecting patients most likely to benefit from the Bcl-2-targeted molecular therapy.

Drug development for metastatic castration-resistant prostate cancer: current status and future perspectives

Prostate cancer represents a third of all newly diagnosed cancers in men in the USA with an estimated incidence of 192,280 cases and 27,360 deaths in 2009. It continues to be a major cause of cancer-related morbidity and mortality, and there is an urgent need for new treatments. Historically, systemic therapy options were limited after progression on docetaxel-based chemotherapy. This article reviews current data on the novel therapeutics demonstrating activity in metastatic castration-resistant prostate cancer and their future role in the treatment of this disease with a poor prognosis.

Update on castrate-resistant prostate cancer: 2010

PURPOSE OF REVIEW

Prostate cancer remains a medical dilemma and a major cause of morbidity and mortality in many western countries. It represents the most common cancer in US men, with an estimated 192 280 new cases diagnosed in 2009. The median survival for men with metastatic castrate-resistant prostate cancer is 1-2 years, with improvements in survival seen primarily with docetaxel-based therapies. The purpose of this article is to discuss developments of novel agents in the field of metastatic castration-resistant prostate cancer (CRPC), including new cytotoxic agents, immune-based therapies, circulating tumor markers and targeting agents.

RECENT FINDINGS

During this past year, several promising approaches yielded disappointing results in the phase III setting (GVAX); nonetheless, expectations for other agents (Abiraterone, MDV3100, Zibotentan, immunotherapy agents) still remain high.

SUMMARY

Systemic therapy options are limited in CRPC and survival benefit remains to be seen with the new therapies. Circulating tumor cells continue to provide important prognostic information and will likely become an important aspect of future clinical decision-making.

Castration-refractory prostate cancer: New drugs in the pipeline

The standard treatment for patients with castration-refractory prostate cancer (CRPC) is the combination docetaxel-prednisone, if the patient can support chemotherapy. Several new treatments have been tested in chemotherapy-naïve or docetaxel-pretreated patients with CRPC. Some of these treatments have shown activity in first-line and second-line treatment. In this review, an update is given of new treatment studies performed in patients with CRPC.

Angiogenesis inhibition in prostate cancer: current uses and future promises

Angiogenesis has been well recognized as a fundamental part of a multistep process in the evolution of cancer progression, invasion, and metastasis. Strategies for inhibiting angiogenesis have been one of the most robust fields of cancer investigation, focusing on the vascular endothelial growth factor (VEGF) family and its receptors. There are numerous regulatory drug approvals to date for the use of these agents in treating a variety of solid tumors. While therapeutic efficacy has been established, challenges remain with regards to overcoming resistance and assessing response to antiangiogenic therapies. Prostate cancer is the most common noncutaneous malignancy among American men and angiogenesis plays a role in disease progression. The use of antiangiogenesis agents in prostate cancer has been promising and is hereby explored.

Angiogenesis inhibition in the treatment of prostate cancer

For many men, prostate cancer is an indolent disease that, even without definitive therapy, may have no impact on their quality of life or overall survival. However for those men who are either diagnosed with or eventually develop metastatic disease, prostate cancer is a painful and universally fatal disease. Testosterone-lowering hormonal therapy may control the disease for some time, but patients eventually develop resistance and progress clinically. At this point, only docetaxel has been shown to improve survival, so clearly additional therapeutic options are needed. Angiogenesis inhibition is an active area of clinical research in prostate cancer. Without angiogenesis, tumors have insufficient nutrients and oxygen to grow larger than a few millimeters and are potentially less likely to metastasize. In prostate cancer in particular, angiogenesis plays a significant role in tumor proliferation, and markers of angiogenesis appear to have prognostic significance. Several different compounds have been developed to inhibit angiogenesis, including monoclonal antibodies, multitargeted kinase inhibitors, and fusion proteins. In addition, more traditional agents may also have an impact on angiogenesis. Trials studying antiangiogenic agents have been conducted in localized and advanced prostate cancer. There are several large, ongoing phase III trials in metastatic castration-resistant prostate cancer. The findings of these and future studies will ultimately determine the role of angiogenesis inhibitors in the treatment of prostate cancer.