A pilot window-of-opportunity study of preoperative fluvastatin in localized prostate cancer

Abstract

Background: Statins inhibit HMG-CoA reductase, the rate-limiting enzyme of the mevalonate pathway. Epidemiological and pre-clinical evidence support an association between statin use and delayed prostate cancer (PCa) progression. Here, we evaluated the effects of neoadjuvant fluvastatin treatment on markers of cell proliferation and apoptosis in men with localized PCa.

Methods: Thirty-three men were treated daily with 80 mg fluvastatin for 4-12 weeks in a single-arm window-of-opportunity study between diagnosis of localized PCa and radical prostatectomy (RP) (ClinicalTrials.gov: NCT01992042). Percent Ki67 and cleaved Caspase-3 (CC3)-positive cells in tumor tissues were evaluated in 23 patients by immunohistochemistry before and after treatment. Serum and intraprostatic fluvastatin concentrations were quantified by liquid chromatography-mass spectrometry.

Results: Baseline characteristics included a median prostate-specific antigen (PSA) level of 6.48 ng/mL (IQR: 4.21-10.33). The median duration of fluvastatin treatment was 49 days (range: 27-102). Median serum low-density lipoprotein levels decreased by 35% after treatment, indicating patient compliance. Median PSA decreased by 12%, but this was not statistically significant in our small cohort. The mean fluvastatin concentration measured in the serum was 0.2 μM (range: 0.0-1.1 μM), and in prostatic tissue was 8.5 nM (range: 0.0-77.0 nM). At these concentrations, fluvastatin induced PCa cell death in vitro in a dose- and time-dependent manner. In patients, fluvastatin treatment did not significantly alter intratumoral Ki67 positivity; however, a median 2.7-fold increase in CC3 positivity (95% CI: 1.9-5.0, p = 0.007) was observed in post-fluvastatin RP tissues compared with matched pre-treatment biopsy controls. In a subset analysis, this increase in CC3 was more pronounced in men on fluvastatin for >50 days.

Conclusions: Fluvastatin prior to RP achieves measurable drug concentrations in prostatic tissue and is associated with promising effects on tumor cell apoptosis. These data warrant further investigation into the anti-neoplastic effects of statins in prostate tissue.

Conflict of interest statement

The authors declare that they have no conflict of interest.

Figures

Fig. 1. Study overview.

a CONSORT diagram and b schematic of the study.

Fig. 2. Serum and tissue measurements before and after fluvastatin treatment, and effects of fluvastatin on PCa cell death.

a Median (IQR) values are reported, unless otherwise indicated. Statistical comparisons (p values) are the result of Wilcoxon matched-pairs signed rank tests. *LLOQ: 5 ng/mL; **LLOQ: 0.25 ng/g; 28 of the 33 enrolled patients were evaluated. HDL high-density lipoprotein, LH luteinizing hormone, FSH follicle-stimulating hormone, N/A not applicable. b Fluvastatin concentrations in the serum and prostate tissue of patients were quantified by HPLC-MS/MS. Data are represented as the mean ± SD. c PC-3 cells were treated with a range of fluvastatin concentrations measurable in prostatic tissue (0–100 nM) for 3 or 7 days, and cell death was quantified using live-cell imaging analysis. Data are represented as the mean + SD, n = 3. *p < 0.05 (one-way ANOVA with Bonferroni’s multiple comparisons test, where each group was compared with the corresponding solvent control). d Representative PC-3 live-cell images. Treated cells were stained with DRAQ5 (red) to identify all nuclei in the well and to score nuclear condensation in response to fluvastatin treatment, as well as TMRE (orange) to identify cells with healthy and active mitochondria. Nuclear condensation and the loss of TMRE staining are markers of cell death. Examples of dead cells are indicated by the white arrows.

Fig. 3. Effects of fluvastatin on intratumoral proliferation and apoptosis.

Percentage of (a) Ki67- and (b) cleaved Caspase-3 (CC3)-positive tumor cells in pre-treatment biopsy and post-fluvastatin RP tissues (log transformed). Patients were subsequently subdivided based on the duration of fluvastatin treatment (<50 or >50 days). c Ki67 and d CC3 positivity in pre-treatment biopsy and post-fluvastatin RP tissues (log transformed), subdivided based on the duration of fluvastatin treatment. Data are represented as the mean ± 95% CI. Statistical comparisons (p values) are the result of Wilcoxon matched-pairs signed rank tests.