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Androgen deprivation therapy is a cornerstone of prostate cancer treatment. Pharmacological androgen deprivation includes gonadotropin-releasing hormone agonism and antagonism, androgen receptor inhibition, and CYP17 (cytochrome P450 17A1) inhibition. Studies in the past decade have raised concerns about the potential for androgen deprivation therapy to increase the risk of adverse cardiovascular events such as myocardial infarction, stroke, and cardiovascular mortality, possibly by exacerbating cardiovascular risk factors. In this review, we summarize existing data on the cardiovascular effects of androgen deprivation therapy. Among the therapies, abiraterone stands out for increasing risk of cardiac events in meta-analyses of both randomized controlled trials and observational studies. We find a divergence between observational studies, which show consistent positive associations between androgen deprivation therapy use and cardiovascular disease, and randomized controlled trials, which do not show these associations reproducibly.
BACKGROUND - Abiraterone and enzalutamide are recently-approved androgen deprivation therapies (ADTs) for metastatic prostate cancer, with unknown cardiac safety profiles. Abiraterone has a propensity to hypermineralocorticism on top of androgen deprivation, so might carry an additional risk for atrial tachyarrhythmia (AT) and heart failure (HF) compared with other ADTs.
AIM - To determine if abiraterone was associated with an increased proportion of AT and HF reports among all suspected adverse drug reactions (ADRs) reported in several pharmacovigilance databases compared with enzalutamide, other ADTs and all other drugs.
METHODS - In this observational retrospective pharmacovigilance study, we performed a disproportionality analysis of reports of suspected ADRs in men in the French pharmacovigilance database, the European pharmacovigilance database and the international pharmacovigilance database VigiBase, to evaluate the reporting odds ratios (RORs) of AT and HF for abiraterone compared with enzalutamide, other ADTs and all other drugs.
RESULTS - In the 5,759,781 ADR reports in men in VigiBase, 55,070 pertained to ADTs. The RORs for AT for abiraterone versus enzalutamide, other ADTs and all other drugs were 4.1 (95% confidence interval 3.1-5.3), 3.7 (3-4.5) and 3.2 (2.7-3.7), respectively (P<0.0001 for all). The corresponding RORs for HF were 2.5 (2-3), 1.5 (1.3-1.7) and 2 (1.7-2.3), respectively (P<0.0001 for all). These results were concordant with the French and European pharmacovigilance databases. Mean times to AT and HF onset were shorter with abiraterone (5.2±0.8 and 4.5±0.6 months, respectively) versus other ADTs (13.3±3.2 and 9.2±1.1 months, respectively) (both P<0.05). Cases on abiraterone versus other ADTs were more frequently associated with at least two ADR terms, including AT, HF, hypokalaemia, hypertension and oedema (13.6% vs 6%; P<0.0001). For abiraterone, age, but not dose, was associated with reporting of AT and HF versus any other ADR.
CONCLUSIONS - Compared with other ADTs, abiraterone was associated with higher reporting of AT and HF, associated with hypokalaemia, hypertension and oedema. These findings are consistent with the hypermineralocorticism induced by abiraterone, but not by other ADTs.
Copyright © 2019 Elsevier Masson SAS. All rights reserved.
BACKGROUND - Prostate cancer is poorly responsive to immune checkpoint inhibition, yet a combination with radiotherapy may enhance the immune response. In this study, we combined radiotherapy with immune checkpoint inhibition (iRT) in a castration-resistant prostate cancer (CRPC) preclinical model.
METHODS - Two Myc-CaP tumor grafts were established in each castrated FVB mouse. Anti-PD-1 or anti-PD-L1 antibodies were given and one graft was irradiated 20 Gy in 2 fractions.
RESULTS - In CRPC, a significant increase in survival was found for radiation treatment combined with either anti-PD-1 or anti-PD-L1 compared to monotherapy. The median survival for anti-PD-L1 alone was 13 days compared to 30 days for iRT (p = 0.0003), and for anti-PD-1 alone was 21 days compared to 36 days for iRT (p = 0.0009). Additional treatment with anti-CD8 antibody blocked the survival effect. An abscopal treatment effect was observed for iRT in which the unirradiated graft responded similarly to the irradiated graft in the same mouse. At 21 days, the mean graft volume for anti-PD-1 alone was 2094 mm compared to iRT irradiated grafts 726 mm (p = 0.04) and unirradiated grafts 343 mm (p = 0.0066). At 17 days, the mean graft volume for anti-PD-L1 alone was 1754 mm compared to iRT irradiated grafts 284 mm (p = 0.04) and unirradiated grafts 556 mm (p = 0.21). Flow cytometry and immunohistochemistry identified CD8+ immune cell populations altered by combination treatment in grafts harvested at the peak effect of immunotherapy, 2-3 weeks after starting treatment.
CONCLUSIONS - These data provide preclinical evidence for the use of iRT targeting PD-1 and PD-L1 in the treatment of CRPC. Immune checkpoint inhibition combined with radiotherapy treats CPRC with significant increases in median survival compared to drug alone: 70% longer for anti-PD-1 and 130% for anti-PD-L1, and with an abscopal treatment effect.
PRECIS - Castration-resistant prostate cancer in a wild-type mouse model is successfully treated by X-ray radiotherapy combined with PD-1 or PD-L1 immune checkpoint inhibition, demonstrating significantly increased median overall survival and robust local and abscopal treatment responses, in part mediated by CD8 T-cells.
Radiation therapy is often combined with androgen deprivation therapy in the treatment of aggressive localized prostate cancer. However, castration-resistant disease may not respond to testosterone deprivation approaches. Enzalutamide is a second-generation anti-androgen with high affinity and activity that is used for the treatment of metastatic disease. Although radiosensitization mechanisms are known to be mediated through androgen receptor activity, this project aims to uncover the detailed DNA damage repair factors influenced by enzalutamide using multiple models of androgen-sensitive (LNCaP) and castration-resistant human prostate cancer (22Rv1 and DU145). Enzalutamide is able to radiosensitize both androgen-dependent and androgen-independent human prostate cancer models in cell culture and xenografts in mice, as well as a treatment-resistant patient-derived xenograft. The enzalutamide-mediated mechanism of radiosensitization includes delay of DNA repair through temporal prolongation of the repair factor complexes and halting the cell cycle, which results in decreased colony survival. Altogether, these findings support the use of enzalutamide concurrently with radiotherapy to enhance the treatment efficacy for prostate cancer.
Radiation therapy is a frequently used modality for the treatment of solid cancers. Although the mechanisms of cell kill are similar for all forms of radiation, the in vivo properties of photon and proton beams differ greatly and maybe exploited to optimize clinical outcomes. In particular, proton particles lose energy in a predictable manner as they pass through the body. This property is used clinically to control the depth at which the proton beam is terminated, and to limit radiation dose beyond the target region. This strategy can allow for substantial reductions in radiation dose to normal tissues located just beyond a tumor target. However, the degradation of proton energy in the body remains highly sensitive to tissue density. As a consequence, any changes in tissue density during the course of treatment may significantly alter proton dosimetry. Such changes may occur through alterations in body weight, respiration, or bowel filling/gas, and may result in unfavorable dose deposition. In this manuscript, we provide a detailed method for the delivery of proton therapy using both passive scatter and pencil beam scanning techniques for prostate cancer. Although the described procedure directly pertains to prostate cancer patients, the method may be adapted and applied for the treatment of virtually all solid tumors. Our aim is to equip readers with a better understanding of proton therapy delivery and outcomes in order to facilitate the appropriate integration of this modality during cancer therapy.
Abnormalities in nuclear shape are a well-known feature of cancer, but their contribution to malignant progression remains poorly understood. Here, we show that depletion of the cytoskeletal regulator, Diaphanous-related formin 3 (DIAPH3), or the nuclear membrane-associated proteins, lamin A/C, in prostate and breast cancer cells, induces nuclear shape instability, with a corresponding gain in malignant properties, including secretion of extracellular vesicles that contain genomic material. This transformation is characterized by a reduction and/or mislocalization of the inner nuclear membrane protein, emerin. Consistent with this, depletion of emerin evokes nuclear shape instability and promotes metastasis. By visualizing emerin localization, evidence for nuclear shape instability was observed in cultured tumor cells, in experimental models of prostate cancer, in human prostate cancer tissues, and in circulating tumor cells from patients with metastatic disease. Quantitation of emerin mislocalization discriminated cancer from benign tissue and correlated with disease progression in a prostate cancer cohort. Taken together, these results identify emerin as a mediator of nuclear shape stability in cancer and show that destabilization of emerin can promote metastasis. This study identifies a novel mechanism integrating the control of nuclear structure with the metastatic phenotype, and our inclusion of two types of human specimens (cancer tissues and circulating tumor cells) demonstrates direct relevance to human cancer. http://cancerres.aacrjournals.org/content/canres/78/21/6086/F1.large.jpg .
©2018 American Association for Cancer Research.
Metastasis is the most lethal aspect of cancer, yet current therapeutic strategies do not target its key rate-limiting steps. We have previously shown that the entry of cancer cells into the blood stream, or intravasation, is highly dependent upon in vivo cancer cell motility, making it an attractive therapeutic target. To systemically identify genes required for tumor cell motility in an in vivo tumor microenvironment, we established a novel quantitative in vivo screening platform based on intravital imaging of human cancer metastasis in ex ovo avian embryos. Utilizing this platform to screen a genome-wide shRNA library, we identified a panel of novel genes whose function is required for productive cancer cell motility in vivo, and whose expression is closely associated with metastatic risk in human cancers. The RNAi-mediated inhibition of these gene targets resulted in a nearly total (>99.5%) block of spontaneous cancer metastasis in vivo.
BACKGROUND - Membrane-associated guanylate kinase, WW and PDZ domain-containing protein 2 (MAGI2) promotes the activity of phosphatase and tensin homolog (PTEN). Recent studies suggest that dysregulation of this signaling pathway has a role in prostate carcinogenesis. Our study aims to determine the prognostic significance of MAGI2 expression in prostate cancer.
METHODS - Tissue microarrays from 51 radical prostatectomy cases including benign prostatic tissue, high grade prostatic intraepithelial neoplasia (HGPIN), and adenocarcinoma were constructed. Immunohistochemistry with double staining for MAGI2 and p63 was performed and analyzed by image analysis as percent of analyzed area (%AREA). Multivariable logistic regression was used to correlate MAGI2 expression with clinical outcomes. Generalized Estimating Equations (GEE) with linear and logistic regression was used to correlate MAGI2 with intrapatient histology.
RESULTS - MAGI2 %AREA was inversely associated with progression from HGPIN to adenocarcinoma of low to high Gleason score (OR, 0.980; slope, -0.02; P = 0.005) and HGPIN to cancer of any Gleason score (OR, 0.969; P = 0.007). After adjusting for grade, stage, and margin status, MAGI2 %AREA was a significant independent predictor of biochemical recurrence (BCR) (OR, 0.936; 95%CI, 0.880-0.996; P = 0.037; bootstrap P = 0.017). The addition of MAGI2 %AREA to these standard clinical parameters improved accuracy of predicting BCR by 2.9% (91.0% vs 88.1%).
CONCLUSIONS - These results reveal that MAGI2 expression is reduced during prostate cancer progression and that retention of MAGI2 signal reduces odds of BCR. The study results further suggest a possible role of MAGI2 in prostate neoplasia. Decreased MAGI2 expression may help predict prostate cancer aggressiveness and provide new insight for treatment decisions and post-operative surveillance intervals.
© 2018 Wiley Periodicals, Inc.
Cancer-associated fibroblasts (CAFs) are major components of the carcinoma microenvironment that promote tumor progression. However, the mechanisms by which CAFs regulate cancer cell migration are poorly understood. In this study, we show that fibronectin (Fn) assembled by CAFs mediates CAF-cancer cell association and directional migration. Compared with normal fibroblasts, CAFs produce an Fn-rich extracellular matrix with anisotropic fiber orientation, which guides the cancer cells to migrate directionally. CAFs align the Fn matrix by increasing nonmuscle myosin II- and platelet-derived growth factor receptor α-mediated contractility and traction forces, which are transduced to Fn through α5β1 integrin. We further show that prostate cancer cells use αv integrin to migrate efficiently and directionally on CAF-derived matrices. We demonstrate that aligned Fn is a prominent feature of invasion sites in human prostatic and pancreatic carcinoma samples. Collectively, we present a new mechanism by which CAFs organize the Fn matrix and promote directional cancer cell migration.
© 2017 Erdogan et al.
PURPOSE - The identification and targeting of biomarkers specific to prostate cancer (PCa) could improve its detection. Given the high expression of translocator protein (TSPO) in PCa, we investigated the use of [F]VUIIS1008 (a novel TSPO-targeting radioligand) coupled with positron emission tomography (PET) to identify PCa in mice and to characterize their TSPO uptake.
PROCEDURES - Pten, Trp53 prostate cancer-bearing mice (n = 9, 4-6 months old) were imaged in a 7T MRI scanner for lesion localization. Within 24 h, the mice were imaged using a microPET scanner for 60 min in dynamic mode following a retro-orbital injection of ~ 18 MBq [F]VUIIS1008. Following imaging, tumors were harvested and stained with a TSPO antibody. Regions of interest (ROIs) were drawn around the tumor and muscle (hind limb) in the PET images. Time-activity curves (TACs) were recorded over the duration of the scan for each ROI. The mean activity concentrations between 40 and 60 min post radiotracer administration between tumor and muscle were compared.
RESULTS - Tumor presence was confirmed by visual inspection of the MR images. The uptake of [F]VUIIS1008 in the tumors was significantly higher (p < 0.05) than that in the muscle, where the percent injected dose per unit volume for tumor was 7.1 ± 1.6 % ID/ml and that of muscle was < 1 % ID/ml. In addition, positive TSPO expression was observed in tumor tissue analysis.
CONCLUSIONS - The foregoing preliminary data suggest that TSPO may be a useful biomarker of PCa. Therefore, using TSPO-targeting PET ligands, such as [F]VUIIS1008, may improve PCa detectability and characterization.