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

Hypertension and hand-foot skin reactions related to VEGFR2 genotype and improved clinical outcome following bevacizumab and sorafenib

BACKGROUND: Hypertension (HT) and hand-foot skin reactions (HFSR) may be related to the activity of bevacizumab and sorafenib. We hypothesized that these toxicities would correspond to favorable outcome in these drugs, that HT and HFSR would coincide, and that VEGFR2 genotypic variation would be related to toxicity and clinical outcomes. METHODS: Toxicities (≥ grade 2 HT or HFSR), progression-free survival (PFS), and overall survival (OS) following treatment initiation were evaluated. Toxicity incidence and VEGFR2 H472Q and V297I status were compared to clinical outcomes. RESULTS: Individuals experiencing HT had longer PFS following bevacizumab therapy than those without this toxicity in trials utilizing bevacizumab in patients with prostate cancer (31.5 vs 14.9 months, n = 60, P = 0.0009), and bevacizumab and sorafenib in patients with solid tumors (11.9 vs. 3.7 months, n = 27, P = 0.052). HT was also linked to a > 5-fold OS benefit after sorafenib and bevacizumab cotherapy (5.7 versus 29.0 months, P = 0.0068). HFSR was a marker for prolonged PFS during sorafenib therapy (6.1 versus 3.7 months respectively, n = 113, P = 0.0003). HT was a risk factor for HFSR in patients treated with bevacizumab and/or sorafenib (OR(95%CI) = 3.2(1.5-6.8), P = 0.0024). Carriers of variant alleles at VEGFR2 H472Q experienced greater risk of developing HT (OR(95%CI) = 2.3(1.2 - 4.6), n = 170, P = 0.0154) and HFSR (OR(95%CI) = 2.7(1.3 - 5.6), n = 170, P = 0.0136). CONCLUSIONS: This study suggests that HT and HFSR may be markers for favorable clinical outcome, HT development may be a marker for HFSR, and VEGFR2 alleles may be related to the development of toxicities during therapy with bevacizumab and/or sorafenib

Samarium-153-EDTMP (Quadramet®) With or Without Vaccine in Metastatic Castration-Resistant Prostate Cancer: A Randomized Phase 2 Trial

PSA-TRICOM is a therapeutic vaccine in late stage clinical testing in metastatic castration-resistant prostate cancer (mCRPC). Samarium-153-ethylene diamine tetramethylene phosphonate (Sm-153-EDTMP; Quadramet®), a radiopharmaceutical, binds osteoblastic bone lesions and emits beta particles causing local tumor cell destruction. Preclinically, Sm-153-EDTMP alters tumor cell phenotype facilitating immune-mediated killing. This phase 2 multi-center trial randomized patients to Sm-153-EDTMP alone or with PSA-TRICOM vaccine. Eligibility required mCRPC, bone metastases, prior docetaxel and no visceral disease. The primary endpoint was the proportion of patients without radiographic disease progression at 4 months. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and immune responses. Forty-four patients enrolled. Eighteen and 21 patients were evaluable for the primary endpoint in Sm-153-EDTMP alone and combination arms, respectively. There was no statistical difference in the primary endpoint, with two of 18 (11.1%) and five of 21 (23.8%) in Sm-153-EDTMP alone and combination arms, respectively, having stable disease at approximately the 4-month evaluation time point (P = 0.27). Median PFS was 1.7 vs. 3.7 months in the Sm-153-EDTMP alone and combination arms (P = 0.041, HR = 0.51, P = 0.046). No patient in the Sm-153-EDTMP alone arm achieved prostate-specific antigen (PSA) decline \u3e 30% compared with four patients (of 21) in the combination arm, including three with PSA decline \u3e 50%. Toxicities were similar between arms and related to number of Sm-153-EDTMP doses administered. These results provide the rationale for clinical evaluation of new radiopharmaceuticals, such as Ra-223, in combination with PSA-TRICOM

The genetics of castration-resistant prostate cancer: what can the germline tell us?

Androgen deprivation therapy (ADT) is the cornerstone treatment for advanced prostate cancer. Despite frequent responses, the majority of metastatic tumors will progress to castration-resistant prostate cancer. Numerous molecular and genetic perturbations have been described in castration-resistant prostate cancer, which are attributable for gain-of- function changes in the androgen receptor, allowing for cell survival and proliferation with castrate levels of testosterone. The utility of these somatic perturbations, which are selected for in the tumor after ADT, for prognostication of response and response duration in metastatic prostate cancer, is problematic. Here, we discuss recent studies that describe germline polymorphisms that determine the response to ADT. Coding and noncoding germline polymorphisms in genes involved in the androgen pathway affect the response to ADT. These polymorphisms require further study and validation. However, they have the potential to be useful for prognosticating the response to ADT, designing clinical trials for patients who have poor germline prognostic features and designing novel therapies targeted against genes that influence the response to ADT

Secondary hormonal therapy for prostate cancer: what lies on the horizon?

Androgen deprivation therapy with medical or surgical castration is generally the first-line treatment against advanced prostate cancer. Almost invariably, metastatic prostate cancer overcomes testosterone depletion and grows, despite castrate levels of testosterone. Despite advances in cytotoxic chemotherapy, secondary hormonal therapies are often used after the development of castrate-resistant prostate cancer. Secondary hormonal therapies either lower the androgen levels further or directly antagonize the androgen receptor in prostate cancer cells. We discuss novel secondary hormonal agents that are under development, which work by either inhibiting androgen synthesis or directly targeting the androgen receptor

An update on androgen deprivation therapy for prostate cancer

Androgen deprivation therapy (ADT) with gonadal testosterone depletion is the frontline treatment for advanced prostate cancer. Other hormonal interventions have a role in the treatment of prostate cancer. We sought to examine systematically the evidence for hormonal interventions in prostate cancer, risks of ADT, and interventions that mitigate these risks. Search results for therapeutic studies were focused primarily on randomized controlled clinical trials, and the Jadad scale criteria were used to evaluate the quality of these studies. Four trials of the efficacy of intermittent ADT versus continuous ADT were included. One randomized study analysis and six postrandomization analyses were included on the effects of ADT on cardiovascular mortality. Seven randomized controlled trials of pharmacologic interventions were included for the treatment of metabolic effects due to ADT. One randomized trial of GnRH antagonist versus GnRH agonist was included. Six phase I/II clinical trials of secondary hormonal therapies with novel mechanisms of action were included. Randomized studies completed to date indicate that intermittent ADT might be equivalent to continuous ADT. Although adverse effects of ADT include risk factors for cardiovascular disease, effects on cardiovascular mortality are uncertain. Bone loss and increased risk of fracture may be effectively treated with pharmacologic interventions. Benefits of ADT must be balanced with a consideration of the risks