Dataset Information

Testosterone Diminishes Cabazitaxel Efficacy and Intratumoral Accumulation in a Prostate Cancer Xenograft Model.

ABSTRACT: Inactivation of the androgen receptor (AR) pathway by androgen deprivation therapy (ADT) is the mainstay of (metastatic) prostate cancer therapy. Ultimately, the AR pathway will be re-activated despite castrate levels of circulating androgens. Thereby, maintaining its role even in castration resistant prostate cancer (CRPC). The recent STAMPEDE and CHAARTED trials showed that docetaxel in combination with ADT increased survival in hormone sensitive prostate cancer patients, suggesting cross-talk between AR signaling and chemotherapy efficacy. We hypothesized that a similar interaction may also apply for CRPC that is treated with cabazitaxel. We studied the impact of androgen status on the efficacy, pharmacodynamics and -kinetics of cabazitaxel in a unique and clinically relevant patient derived xenograft model of castration resistant disease. We found that cabazitaxel is highly effective in a castrate setting with strongly reduced AR activation, while tumor growth inhibition by cabazitaxel was completely abolished in the presence of high AR pathway activity. Moreover, additional experiments showed that intratumoral cabazitaxel levels were 3.5 times higher in tumors from castrated mice as compared to tumors from androgen-supplemented animals. We confirmed that cabazitaxel pharmacokinetics were not affected by testosterone, suggesting that androgen status might influence cabazitaxel tumor uptake directly. This study reveals the impact of androgen status on cabazitaxel efficacy and supports the potential of combination of taxane chemotherapeutics with AR axis targeting agents.

SUBMITTER: Mout L

PROVIDER: S-EPMC5828553 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Testosterone Diminishes Cabazitaxel Efficacy and Intratumoral Accumulation in a Prostate Cancer Xenograft Model.

Mout Lisanne L de Wit Ronald R Stuurman Debra D Verhoef Esther E Mathijssen Ron R de Ridder Corrina C Lolkema Martijn M van Weerden Wytske W

EBioMedicine 20171220

Inactivation of the androgen receptor (AR) pathway by androgen deprivation therapy (ADT) is the mainstay of (metastatic) prostate cancer therapy. Ultimately, the AR pathway will be re-activated despite castrate levels of circulating androgens. Thereby, maintaining its role even in castration resistant prostate cancer (CRPC). The recent STAMPEDE and CHAARTED trials showed that docetaxel in combination with ADT increased survival in hormone sensitive prostate cancer patients, suggesting cross-talk ...[more]

PMID: 29276148

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Project description:Background:Several studies have reported the efficacy of cabazitaxel in cancer therapy; however, investigations of its safety are few. The aim of this study was to retrospectively analyze the efficacy and safety of cabazitaxel based on treatment outcome data. Methods:A questionnaire form on the use of cabazitaxel was mailed to hospitals associated with the Shinshu University. Responses were received from 11 institutions regarding 55 cases. Results:Patients received a median of 4 courses of cabazitaxel treatment. Decreases in prostrate-specific antigen (PSA) were observed in 61.5% of cases with declines of 30%, 50%, and 90% in 36.5%, 23.0%, and 7.6% of cases, respectively. PSA progression-free survival was 5.0 months, and overall survival after the start of cabazitaxel was 13.0 months. Forty-five patients received postcabazitaxel treatment; 17 showed decreased PSA. Safety assessment indicated that white blood cell and neutrophil counts were significantly higher in the second than in the first course of treatment and Grade 3 to 4 leukopenia and neutropenia significantly decreased. Twenty-four subjects were aged ?75 years; 79% of them had their doses reduced at the first administration. The mean dose was 20 mg/m2. However, there was no significant difference in the PSA progression-free survival between the ?75-year-old and <75-year-old groups. Patients in the ?75-year-old group, particularly those whose doses were not reduced, experienced several Grade 3 to 4 adverse effects. Ten patients discontinued treatment owing to adverse effects and systemic worsening. Conclusions:To use cabazitaxel effectively, starting administration as early as possible before disease progression is important, and even if Grade 3 to 4 leukopenia and neutropenia are observed during the first course, it is important to carefully maintain the dose. Even when treating elderly patients, reducing the dose does not reduce therapeutic efficacy. However, because this cohort experienced several ? Grade 3 adverse effects, a great deal of caution is required.

Project description:BackgroundTestosterone is a driver of prostate cancer (PC) growth via ligand-mediated activation of the androgen receptor (AR). Tumors that have escaped systemic androgen deprivation, castration-resistant prostate cancers (CRPC), have measurable intratumoral levels of testosterone, suggesting that a resistance mechanism still depends on androgen-simulated growth. However, AR activation requires an optimal intracellular concentration of androgens, a situation challenged by low circulating testosterone concentrations. Notably, PC cells may optimize their androgen levels by regulating the expression of steroid metabolism enzymes that convert androgen precursors into androgens. Here we propose that testosterone entry into the cell could be another control point.MethodsTo determine whether testosterone enters cells via a transporter, we performed in vitro 3 H-testosterone uptake assays in androgen-dependent LNCaP and androgen and AR-independent PC3 cells. To determine if the uptake mechanism depended on a concentration gradient, we modified UGT2B17 levels in LNCaP cells and measured androgen levels by liquid-liquid extraction-mass spectrometry. We also analyzed CRPC metastases for expression of AKR1C3 to determine whether this enzyme that converts adrenal androgens to testosterone was present in the tumor stroma (microenvironment) in addition to its expression in the tumor epithelium.ResultsTestosterone uptake followed a concentration gradient but unlike in passive diffusion, was saturable and temperature-dependent, thus suggesting facilitated transport. Suppression of UGT2B17 to abrogate a testosterone gradient reduced testosterone transport while overexpression of the enzyme enhanced it. The facilitated transport suggests a paracrine route of testosterone uptake for maintaining optimal intracellular levels. We found that AKR1C3 was expressed in the tumor microenvironment of CRPC metastases in addition to epithelial cells and the pattern of relative abundance of the enzyme in epithelium vs stroma varied substantially between the metastatic sites.ConclusionsOur findings suggest that in addition to testosterone transport and metabolism by tumor epithelium, testosterone could also be produced by components of the tumor microenvironment. Facilitated testosterone uptake by tumor cells supports a cell nonautonomous mechanism for testosterone signaling in CRPC.

Dataset Information

Testosterone Diminishes Cabazitaxel Efficacy and Intratumoral Accumulation in a Prostate Cancer Xenograft Model.

Publications

Testosterone Diminishes Cabazitaxel Efficacy and Intratumoral Accumulation in a Prostate Cancer Xenograft Model.

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