Developing oncolytic viruses for clinical use: A consortium approach

The use of oncolytic viruses forms an appealing approach for cancer treatment. On the one hand the viruses replicate in, and kill, tumor cells, leading to their intra-tumoral amplification. On the other hand the viral infection will activate virus-directed immune responses, and may trigger immune responses directed against tumor cells and tumor antigens. To date, a wide variety of oncolytic viruses is being developed for use in cancer treatment. While the development of oncolytic viruses has often been initiated by researchers in academia and other public institutions, a large majority of the final product development and the testing of these products in clinical trials is industry led. As a consequence relatively few pre-clinical and clinical studies evaluated different oncolytic viruses i

Nuclear Eg5 (kinesin spindle protein) expression predicts docetaxel response and prostate cancer aggressiveness

Novel biomarkers predicting prostate cancer (PCa) aggressiveness and docetaxel therapy response of PCa patients are needed. In this study the correlation between nuclear Eg5-expression, PCa docetaxel response and PCa aggressiveness was assessed. Immunohistochemical staining for nuclear Eg5 was performed on 117 archival specimens from 110 PCa patients treated with docetaxel between 2004 and 2012. Samples were histologically categorized as positive/negative. Median follow-up time from diagnosis was 11.6 years. Nuclear Eg5-expression was significantly related to docetaxel response (p=0.036) in tissues acquired within three years before docetaxel initiation. Nuclear Eg5-expression was not related to Gleason-score (p=0.994). Survival of patients after docetaxel initiation did not differ based on nuclear Eg5-expression (p=0.540). Analyzing samples taken before hormonal therapy, overall survival and time to docetaxel use were significantly decreased in patients with nuclear Eg5-expressing tumors (p<0.01). Eg5-positive nuclei were found more frequently in T4-staged tumors (p=0.04), Gleason 8-10 tumors (p=0.08), and in metastasized tumors (p<0.01). Multivariate analyses indicated that nuclear Eg5-expression may be an independent parameter for tumor aggressiveness. Limitations of a retrospective analysis apply. In conclusion, nuclear Eg5-expression may be a predictive biomarker for docetaxel response in metastatic castrate-resistant PCa patients and a prognostic biomarker for hormone-naive PCa patients. Prospective validation studies are needed

The aldehyde dehydrogenase enzyme 7A1 is functionally involved in prostate cancer bone metastasis

High aldehyde dehydrogenase (ALDH) activity can be used to identify tumor-initiating and metastasis-initiating cells in various human carcinomas, including prostate cancer. To date, the functional importance of ALDH enzymes in prostate carcinogenesis, progression and metastasis has remained elusive. Previously we identified strong expression of ALDH7A1 in human prostate cancer cell lines, primary tumors and matched bone metastases. In this study, we evaluated whether ALDH7A1 is required for the acquisition of a metastatic stem/progenitor cell phenotype in human prostate cancer. Knockdown of ALDH7A1 expression resulted in a decrease of the α2hi/αvhi/CD44+ stem/progenitor cell subpopulation in the human prostate cancer cell line PC-3M-Pro4. In addition, ALDH7A1 knockdown significantly inhibited the clonogenic and migratory ability of human prostate cancer cells in vitro. Furthermore, a number of genes/factors involved in migration, invasion and metastasis were affected including transcription factors (snail, snail2, and twist) and osteopontin, an ECM molecule involved in metastasis. Knockdown of ALDH7A1 resulted in decreased intra-bone growth and inhibited experimentally induced (bone) metastasis, while intra-prostatic growth was not affected. In line with these observations, evidence is presented that TGF-β, a key player in cancer invasiveness and bone metastasis, strongly induced ALDH activity while BMP7 (an antagonist of TGF-β signaling) down-regulated ALDH activity. Our findings show, for the first time, that the ALDH7A1 enzyme is functionally involved in the formation of bone metastases and that the effect appeared dependent on the microenvironment, i.e., bone versus prostate

Liposomal nanomedicines in the treatment of prostate cancer

Prostate cancer is the most common cancer type and the second leading cause of death from cancer in males. In most cases, no curative treatment options are available for metastatic castration-resistant prostate cancer as these tumors are highly resistant to chemotherapy. Targeted drug delivery, using liposomal drug delivery systems, is an attractive approach to enhance the efficacy of anticancer drugs and prevent side effects, thereby potentially increasing the therapeutic index. In most preclinical prostate cancer studies, passive liposomal targeting of anticancer drugs (caused by enhanced permeability and retention of the therapeutic compound) leads to an increased antitumor efficacy and decreased side effects compared to non-targeted drugs. As a result, the total effective dose of anticancer drugs can be substantially decreased. Active (ligand-mediated) liposomal targeting of tumor cells and/or tumor-associated stromal cells display beneficial effects, but only limited preclinical studies were reported. To date, clinical studies in prostate carcinoma have been performed with liposomal doxorubicin only. These studies showed that long-circulating, PEGylated, liposomal doxorubicin generally outperforms conventional short-circulating liposomal doxorubicin, stressing the importance of passive tumor targeting for this drug in prostate carcinoma. In this review, we provide an overview of the (pre)clinical studies that focus on liposomal drug delivery in prostate carcinoma

Liposomal nanomedicines in the treatment of prostate cancer

Prostate cancer is the most common cancer type and the second leading cause of death from cancer in males. In most cases, no curative treatment options are available for metastatic castration-resistant prostate cancer as these tumors are highly resistant to chemotherapy. Targeted drug delivery, using liposomal drug delivery systems, is an attractive approach to enhance the efficacy of anticancer drugs and prevent side effects, thereby potentially increasing the therapeutic index. In most preclinical prostate cancer studies, passive liposomal targeting of anticancer drugs (caused by enhanced permeability and retention of the therapeutic compound) leads to an increased antitumor efficacy and decreased side effects compared to non-targeted drugs. As a result, the total effective dose of anticancer drugs can be substantially decreased. Active (ligand-mediated) liposomal targeting of tumor cells and/or tumor-associated stromal cells display beneficial effects, but only limited preclinical studies were reported. To date, clinical studies in prostate carcinoma have been performed with liposomal doxorubicin only. These studies showed that long-circulating, PEGylated, liposomal doxorubicin generally outperforms conventional short-circulating liposomal doxorubicin, stressing the importance of passive tumor targeting for this drug in prostate carcinoma. In this review, we provide an overview of the (pre)clinical studies that focus on liposomal drug delivery in prostate carcinoma

Improving Taxane-Based Chemotherapy in Castration-Resistant Prostate Cancer

Currently, the clinical utility of taxane-based drug formulations in castration-resistant prostate cancer (CRPC) is severely limited by acquired chemotherapy resistance, dose-limiting toxicities, and nonresponders. Therefore, approaches to improve taxane-based chemotherapy are desperately required. In this review, we highlight the strategies that aim to overcome these limitations, such as bypassing therapy resistance, targeted drug delivery, and adequate prediction of therapy response. The involvement of the apoptotic pathway, ABC transporters, the glucocorticoid receptor (GR) axis, androgen receptor (AR) splicing, epithelial plasticity, and cancer stem cells in mediating taxane-resistance are outlined. Furthermore, passive and active targeted nanomedicinal drug delivery strategies and the use of circulating tumor cells in predicting docetaxel responses are discussed. Finally, recent advances towards clinical translation of these approaches in CRPC are reviewed

Improving Taxane-Based Chemotherapy in Castration-Resistant Prostate Cancer

Currently, the clinical utility of taxane-based drug formulations in castration-resistant prostate cancer (CRPC) is severely limited by acquired chemotherapy resistance, dose-limiting toxicities, and nonresponders. Therefore, approaches to improve taxane-based chemotherapy are desperately required. In this review, we highlight the strategies that aim to overcome these limitations, such as bypassing therapy resistance, targeted drug delivery, and adequate prediction of therapy response. The involvement of the apoptotic pathway, ABC transporters, the glucocorticoid receptor (GR) axis, androgen receptor (AR) splicing, epithelial plasticity, and cancer stem cells in mediating taxane-resistance are outlined. Furthermore, passive and active targeted nanomedicinal drug delivery strategies and the use of circulating tumor cells in predicting docetaxel responses are discussed. Finally, recent advances towards clinical translation of these approaches in CRPC are reviewed

Osteolytic cancer cells induce vascular/axon guidance processes in the bone/bone marrow stroma.

Prostate and breast cancers frequently metastasize to bone. The physiological bone homeostasis is perturbed once cancer cells proliferate at the bone metastatic site. Tumors are complex structures consisting of cancer cells and numerous stroma cells. In this study, we show that osteolytic cancer cells (PC-3 and MDA-MB231) induce transcriptome changes in the bone/bone marrow microenvironment (stroma). This stroma transcriptome differs from the previously reported stroma transcriptome of osteoinductive cancer cells (VCaP). While the biological process "angiogenesis/vasculogenesis" is enriched in both transcriptomes, the "vascular/axon guidance" process is a unique process that characterizes the osteolytic stroma. In osteolytic bone metastasis, angiogenesis is denoted by vessel morphology and marker expression specific for arteries/arterioles. Interestingly, intra-tumoral neurite-like structures were in proximity to arteries. Additionally, we found that increased numbers of mesenchymal stem cells and vascular smooth muscle cells, expressing osteolytic cytokines and inhibitors of bone formation, contribute to the osteolytic bone phenotype. Osteoinductive and osteolytic cancer cells induce different types of vessels, representing functionally different hematopoietic stem cell niches. This finding suggests different growth requirements of osteolytic and osteoinductive cancer cells and the need for a differential anti-angiogenic strategy to inhibit tumor growth in osteolytic and osteoblastic bone metastasis