Current and Emerging Treatment Options for Castration-Resistant Prostate Cancer: A Focus on Immunotherapy

BACKGROUND: Castration-resistant prostate cancer is a disease with limited treatment options. However, the ongoing elucidation of the mechanisms underlying this disease continues to support the development of not only novel agents, but also innovative approaches. Among these therapies, immunotherapy has emerged as a promising strategy. DESIGN: This review article summarizes the most recent data from investigations of immunotherapies in castration-resistant prostate cancer (literature and congress searches current as of August 2011). RESULTS: Immunotherapeutic strategies such as passive immunization, vaccines, and particularly checkpoint blockade have demonstrated some efficacy as single agents. Elucidation of effective combinations of agents and drug regimens is ongoing but will require continued careful investigation, including the standardization of surrogate endpoints in clinical trials. CONCLUSIONS: It is hypothesized that the combination of immunotherapeutic agents with traditional and novel chemotherapeutics will potentiate the efficacy of the chemotherapeutics while maintaining manageable toxicity

A Multisite Preregistered Paradigmatic Test of the Ego-Depletion Effect

We conducted a preregistered multilaboratory project (k = 36; N = 3,531) to assess the size and robustness of ego-depletion effects using a novel replication method, termed the paradigmatic replication approach. Each laboratory implemented one of two procedures that was intended to manipulate self-control and tested performance on a subsequent measure of self-control. Confirmatory tests found a nonsignificant result (d = 0.06). Confirmatory Bayesian meta-analyses using an informed-prior hypothesis (δ = 0.30, SD = 0.15) found that the data were 4 times more likely under the null than the alternative hypothesis. Hence, preregistered analyses did not find evidence for a depletion effect. Exploratory analyses on the full sample (i.e., ignoring exclusion criteria) found a statistically significant effect (d = 0.08); Bayesian analyses showed that the data were about equally likely under the null and informed-prior hypotheses. Exploratory moderator tests suggested that the depletion effect was larger for participants who reported more fatigue but was not moderated by trait self-control, willpower beliefs, or action orientation

Vaccination of colorectal cancer patients with TroVax given alongside chemotherapy (5-fluorouracil, leukovorin and irinotecan) is safe and induces potent immune responses

Modified vaccinia Ankara (MVA) encoding the tumor antigen 5T4 (TroVax®) has been evaluated in an open label phase II study in metastatic colorectal cancer patients. The primary objective was to assess the safety and immunogenicity of TroVax injected before, during and after treatment with 5-fluorouracil, leukovorin and irinotecan. TroVax was administered to 19 patients with metastatic colorectal cancer. Twelve patients had blood samples taken following each of the six injections and were considered to be evaluable for assessment of immunological responses. Both antibody and cellular responses specific for the tumor antigen 5T4 and the viral vector MVA were monitored throughout the study. Administration of TroVax alongside chemotherapy was safe and well tolerated with no SAEs attributed to the vaccine and no enhancement of chemo-related toxicity. Of the 12 patients who were evaluable for assessment of immune responses, ten mounted 5T4-specific antibody responses with titers ranging from 10 to >5,000. IFNγ ELISPOT responses specific for 5T4 were detected in 11 patients with frequencies exceeding one in 1,000 PBMCs in five patients. Eight patients presented with elevated circulating CEA concentrations, six of whom showed decreases in excess of 50% during chemotherapy and four had CEA levels which remained stable for >1 month following completion of chemotherapy. Of the 19 intention to treat (ITT) patients, one had a CR, six had PRs and five had SD. Potent 5T4-specific cellular and/or humoral immune responses were induced in all 12 evaluable patients and were detectable in most patients during the period in which chemotherapy was administered. These data demonstrate that TroVax can be layered on top of chemotherapy regimens without any evidence of enhanced toxicity or reduced immunological or therapeutic efficacy. © 2007 Springer-Verlag