Characterization of prognostic factors and efficacy in a phase-II study with docetaxel and estramustine for advanced hormone refractory prostate cancer

Predicting bone scan positivity in non-metastatic castration-resistant prostate cancer

Objectives

To evaluate PSA levels and kinetic cutoffs to predict positive bone scans for men with non-metastatic castrate resistant prostate cancer (CRPC) from the Shared Equal Access Regional Cancer Hospital (SEARCH) cohort.

Methods

Retrospective analysis of 531 bone scans of 312 clinically CRPC patients with no known metastases at baseline treated with a variety of primary treatment types in the SEARCH database. The association of patients’ demographics, pathological features, PSA levels and kinetics with risk of a positive scan was tested using generalized estimating equations.

Results

A total of 149 (28%) scans were positive. Positive scans were associated with younger age (OR=0.98; P=0.014), higher Gleason scores (relative to Gleason 2-6, Gleason 3+4: OR=2.03, P=0.035; Gleason 4+3 and 8-10: OR=1.76, P=0.059), higher pre-scan PSA (OR=2.11; P<0.001), shorter pre-scan PSA doubling time (PSADT; OR=0.53; P<0.001), higher PSA velocity (OR=1.74; P<0.001) and more remote scan year (OR=0.92; P=0.004). Scan positivity was 6%, 14%, 29% and 57% for men with PSA <5, 5-14.9, 15-49.9 and ≥50ng/mL, respectively (P-trend <0.001). Men with PSADT ≥15, 9-14.9, 3-8.9 and <3 months had a scan positivity of 11%, 22%, 34% and 47%, correspondingly (P-trend <0.001). Tables were constructed using PSA and PSADT to predict the likelihood of a positive bone scan.

Conclusions

PSA levels and kinetics were associated with positive bone scans. We developed tables to predict the risk of positive bone scans by PSA and PSADT. Combining PSA levels and kinetics may help select patients with CRPC for bone scans.

PSA response rate as a surrogate marker for median overall survival in docetaxel-based first-line treatments for patients with metastatic castration-resistant prostate cancer: an analysis of 22 trials

The aim of this study was to determine the correlation between PSA response rate (PSA RR) and overall survival (OS) and identify PSA RR as a potential surrogate for OS, in docetaxel-based first-line treatments for castration-resistant prostate cancer (CRPC). Trials of first-line regimens with docetaxel for patients with metastatic CRCP published between 2004 and 2013 were identified, and data were evaluated statistically in order to investigate the correlation between PSA RR and OS. A total of 22 trials were identified and included in our analysis, for a total of 7,677 patients. In addition, we divided all the trails and arms of the randomized trials in two subgroups, the first one composed only of docetaxel (D) plus prednisone (P) regimens (standard therapy) and the second one composed of all D + other drug combinations (D combinations). Analysing all the trials and arms as a single unit, we found a statistically significant correlation between PSA RR and OS, with Spearman's rank correlation coefficient ρ = 0.50 (95% confidence interval (CI), 0.47 to 0.88) (P = 0.003). Also evaluating the standard therapy group, we found a statistically significant correlation between PSA RR and OS, with Spearman's ρ = 0.65 (95% CI, 0.38 to 0.70) (P = 0.02). However, when we assessed the D combination group, we found Spearman's rank correlation coefficient decreased (ρ = 0.42) (95% CI, 0.28 to 0.80) and resulted nonstatistically significant (P = 0.06). In conclusion, we found a statistically significant correlation between PSA RR and OS. The usage of PSA RR as a surrogate marker for OS in metastatic CRPC patients treated with D-based first-line regimens may be appropriate only in the D + P combination.

Docetaxel: a review of its use for the first-line treatment of advanced castration-resistant prostate cancer

Docetaxel (Taxotere®) is a well established anti-mitotic chemotherapy agent. Among other therapeutic indications, docetaxel plus prednisone is indicated for first-line chemotherapy in patients with castration-resistant prostate cancer (CRPC). Docetaxel every 3 weeks plus continuous prednisone has been standard first-line chemotherapy in CRPC since demonstrating improved survival compared with the previous standard regimen, mitoxantrone plus prednisone, in the phase III TAX 327 trial in 2004. Since that time, docetaxel has been combined with various agents that demonstrated additive or synergistic activity in preclinical studies in an effort to further improve outcomes, but to date, overall survival has not been extended compared with docetaxel plus prednisone. However, several promising agents are emerging with a potential role in docetaxel-based combinations based on efficacy and manageable toxicity, including bevacizumab, dasatinib and atrasentan. In the TAX 327 trial, neutropenia was relatively common in the group receiving 3-weekly docetaxel plus prednisone, but infection was rare. The tolerability of a weekly docetaxel regimen also administered in this trial was not significantly different to that of the 3-weekly regimen, except for a lower incidence of grade 3 or 4 neutropenia. However, weekly or 2-weekly docetaxel administration schedules may have a place in very elderly or frail patients in order to improve tolerability compared with the 3-weekly regimen. In conclusion, docetaxel every 3 weeks plus prednisone remains the optimum first-line chemotherapy for most patients with advanced CRPC until such time that ongoing research with docetaxel and emerging therapeutic agents can demonstrate improved survival.

PEDF inhibits IL8 production in prostate cancer cells through PEDF receptor/phospholipase A2 and regulation of NFκB and PPARγ

Interleukin-8 (IL8/CXCL8) has been described as a key effector in prostate cancer progression and resistance to standard chemotherapeutic drugs. In the present study, we investigated the effect of the natural, angio-inhibitory and anti-tumoral Pigment Epithelium-Derived Factor (PEDF) on the expression of IL8 cytokine by prostate cancer cells. Using a cytokine antibody array and ELISA, in addition to IL8 quantitative RT PCR, we showed that PEDF inhibits the production of IL8 in human hormone-refractory prostate cancer cells, and delays the growth of these cells in vitro. IL8 reduction was mimicked in cancer cells treated with PPARγ agonist and NFκB-specific inhibitors. Accordingly, PPARγ expression increased in response to PEDF, whereas RelA/p65 expression and nuclear localization, and NFκB transcriptional activity decreased. NFκB deactivation was reversed by the PPARγ antagonist GW9662 and PPARγ (Leu(468)/Glu(471)) dominant negative suggesting a PPARγ-dependent process. We also investigated PEDF Receptor/PLA2 as key player in this pathway by small interference RNA. PEDFR knock down in prostate cancer cells reversed PEDF-induced PPARγ up-regulation, and NFκB and IL8 inhibition compared to non-targeting control siRNA. We conclude that by binding to PEDFR, PEDF up-regulates PPARγ, leading subsequently to suppressed NFκB-mediated transcriptional activation, reduced production of IL8 and limited proliferation of prostate cancer cells. These results reinforce PEDF's therapeutic potential and imply that blocking IL8 could represent a novel alternative for prostate cancer treatment.

Impact of PSA flare-up in patients with hormone-refractory prostate cancer undergoing chemotherapy

OBJECTIVES

The intention of this study is to describe the impact and underlying potential basis of the prostate-specific antigen (PSA) flare-up phenomenon in patients with hormone-refractory prostate cancer (HRPC) treated with docetaxel-based chemotherapy.

METHODS

We retrospectively identified 74 consecutive patients who received docetaxel/estramustine-based chemotherapy at our institution. Patients were evaluated based on modified criteria from the Prostate-Specific Antigen Working Group regarding survival and toxicity. Additionally, two androgen receptor mutations derived from patients with advanced disease were analyzed for promiscuous transactivation activity.

RESULTS

The 74 patients were stratified into four groups: response, partial response, flare-up-initial PSA elevation, and progression. Median survival in the flare-up group (n=8) was 20 months and did not differ from the response group (p=0.564). The flare-up group showed a maximum PSA elevation from baseline between 3.4 and 28.3% (between three and six weeks) followed by PSA decline >or=50% from the baseline level in seven of the eight patients. The androgen receptor mutations AR(877) and AR(715) displayed a 37.5- and 5.2-fold increase in transactivation activity by progesterone and a 12.6- and 5.4-fold increase by estrogen compared to the AR(WT), respectively.

CONCLUSIONS

A considerable portion of HRPC patients experience an initial PSA flare-up under systemic chemotherapy. In this study, occurrence of flare-up phenomenon did not impact survival. Chemotherapy should be continued a minimum of six weeks before removing patients from a docetaxel-based regimen. We showed evidence that co-medication with dexamethasone/prednisolone and/or estramustine itself can induce an initial PSA flare-up via androgen receptor mutations.

A randomized study of docetaxel and dexamethasone with low- or high-dose estramustine for patients with advanced hormone-refractory prostate cancer

OBJECTIVE

To test the combination of docetaxel with two different doses of estramustine in patients with hormone-refractory prostate cancer (HRPC), to improve response rates and to lower side-effects, as docetaxel-based chemotherapy is an increasing option for men with advanced HRPC, and alone or combined with estramustine, docetaxel improves median survival.

PATIENTS AND METHODS

In all, 72 patients with metastatic HRPC were randomly assigned to receive docetaxel (70 mg/m(2) intravenously, on day 2 every 21 days) and estramustine (3 x 280 mg/day oral starting 1 day before docetaxel, for 5 consecutive days) for arm A, or estramustine (3 x 140 mg/day oral starting 1 day before docetaxel, for 3 consecutive days) for arm B. Premedication with oral dexamethasone at a total daily dose of 16 mg, in divided doses twice a day was administered in arm A on day 1-5 and in arm B on day 1-3. Initially, six cycles were administered. Chemotherapy was restarted after a significant increase in prostate-specific antigen (PSA) level. Patients were monitored for any measurable PSA response and toxicity.

RESULTS

Between the arms there was no statistically significant difference in time to progression and overall survival. However, treatment B had less treatment-related toxicity than A. Independent prognostic variables were baseline factors like PSA level, haemoglobin level, Eastern Cooperative Oncology Group performance status, and bone pain at presentation.

CONCLUSIONS

In this randomized phase II study the combination of docetaxel and estramustine had substantial activity in HRPC, with a significant incidence of severe toxicity, both haematological and not. Nevertheless, treatment-related toxicity was predictable and manageable. There was no better effect with a higher dose of estramustine with docetaxel than for a lower dose. There was a slight tendency to higher toxicity for high-dose estramustine but this was not statistically significant. The present results support the assertion that estramustine is not necessary in docetaxel-based treatment regimens.