Taxanes in the management of metastatic castration-resistant prostate cancer: efficacy and management of toxicity

Cancer on motors: How kinesins drive prostate cancer progression?

Prostate cancer causes numerous male deaths annually. Although great progress has been made in the diagnosis and treatment of prostate cancer during the past several decades, much about this disease remains unknown, especially its pathobiology. The kinesin superfamily is a pivotal group of motor proteins, that contains a microtubule-based motor domain and features an adenosine triphosphatase activity and motility characteristics. Large-scale sequencing analyses based on clinical samples and animal models have shown that several members of the kinesin family are dysregulated in prostate cancer. Abnormal expression of kinesins could be linked to uncontrolled cell growth, inhibited apoptosis and increased metastasis ability. Additionally, kinesins may be implicated in chemotherapy resistance and escape immunologic cytotoxicity, which creates a barrier to cancer treatment. Here we cover the recent advances in understanding how kinesins may drive prostate cancer progression and how targeting their function may be a therapeutic strategy. A better understanding of kinesins in prostate cancer tumorigenesis may be pivotal for improving disease outcomes in prostate cancer patients.

Safety Analyses of the Phase 3 VISION Trial of [177Lu]Lu-PSMA-617 in Patients with Metastatic Castration-resistant Prostate Cancer

BACKGROUND AND OBJECTIVE

[177Lu]Lu-PSMA-617 (177Lu-PSMA-617) plus the standard of care (SoC) significantly improved overall survival and radiographic progression-free survival versus SoC alone in patients with prostate-specific membrane antigen (PSMA)-positive metastatic castration-resistant prostate cancer in the VISION trial. We evaluated the safety of additional cycles of 177Lu-PSMA-617 and the impact of longer observation time for patients receiving 177Lu-PSMA-617 plus SoC.

METHODS

VISION was an international, open-label study. Patients were randomised 2:1 to receive 177Lu-PSMA-617 plus SoC or SoC alone. The incidence of treatment-emergent adverse events (TEAEs) was assessed in prespecified subgroups of patients who received ≤4 cycles versus 5-6 cycles of treatment and during each cycle of treatment. The TEAE incidence was also adjusted for treatment exposure to calculate the incidence per 100 patient-treatment years of observation. This analysis was performed for the first occurrence of TEAEs.

KEY FINDINGS AND LIMITATIONS

The any-grade TEAE incidence was similar in cycles 1-4 and cycles 5-6. TEAE frequency was similar across all cycles of 177Lu-PSMA-617 treatment. No additional safety concerns were reported for patients who received >4 cycles. The exposure-adjusted safety analysis revealed that the overall TEAE incidence was similar between arms, but distinct trends for different TEAE types were noted and the incidence of events associated with 177Lu-PSMA-617 remained higher in the 177Lu-PSMA-617 arm.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Longer exposure to 177Lu-PSMA-617 plus SoC was not associated with a higher toxicity risk, and the extended time for safety observation could account for the higher TEAE incidence in comparison to SoC alone. The findings support a favourable benefit-risk profile for 6 cycles of 177Lu-PSMA-617 in this setting and the use of up to 6 cycles of 177Lu-PSMA-617 in patients who are clinically benefiting from and tolerating this therapy.

PATIENT SUMMARY

For patients with metastatic prostate cancer no longer responding to hormone therapy, an increase in the number of cycles of treatment with a radioactive compound called 177Lu-PSMA-617 from four to six had no additional adverse side effects.

Renal and Multiorgan Safety of 177Lu-PSMA-617 in Patients with Metastatic Castration-Resistant Prostate Cancer in the VISION Dosimetry Substudy

In the VISION trial, [177Lu]Lu-PSMA-617 (177Lu-PSMA-617) plus protocol-permitted standard of care significantly improved overall survival and radiographic progression-free survival compared with standard of care alone in patients with prostate-specific membrane antigen-positive metastatic castration-resistant prostate cancer. This VISION dosimetry substudy quantified absorbed doses of 177Lu-PSMA-617 in the kidneys and other organs. Methods: Participants were a separate cohort of 30 nonrandomized patients receiving standard of care plus 177Lu-PSMA-617 at 7.4 GBq per cycle for up to 6 cycles. Blood samples, whole-body conjugate planar image scintigraphy, and abdominal SPECT/CT images were collected. SPECT/CT images were collected at 2, 24, 48, and 168 h after administration in cycle 1 and at a single time point 48 h after administration in cycles 2-6. Outcomes were absorbed dose per unit activity per cycle and cumulative absorbed dose over all cycles. Cumulative absorbed doses were predicted by extrapolation from cycle 1, and calculation of observed values was based on measurements of cycle 1 and cycles 2-6. Safety was also assessed. Results: Mean (±SD) absorbed doses per cycle in the kidneys were 0.43 ± 0.16 Gy/GBq in cycle 1 and 0.44 ± 0.21 Gy/GBq in cycles 2-6. The observed and predicted 6-cycle cumulative absorbed doses in the kidneys were 15 ± 6 and 19 ± 7 Gy, respectively. Observed and predicted cumulative absorbed doses were similar in other at-risk organs. Safety findings were consistent with those in the VISION study; no patients experienced renal treatment-emergent adverse events of a grade higher than 3. Conclusion: The renal cumulative absorbed 177Lu-PSMA-617 dose was below the established limit. 177Lu-PSMA-617 had a good overall safety profile, and low renal radiotoxicity was not a safety concern. Cumulative absorbed doses in at-risk organs over multiple cycles can be predicted by extrapolation from cycle 1 data in patients with metastatic castration-resistant prostate cancer receiving 177Lu-PSMA-617.

A VISION Substudy of Reader Agreement on 68Ga-PSMA-11 PET/CT Scan Interpretation to Determine Patient Eligibility for 177Lu-PSMA-617 Radioligand Therapy

⁶⁸Ga-gozetotide (⁶⁸Ga-PSMA-11) is used to identify prostate-specific membrane antigen (PSMA)-positive tumors on PET scans. In the VISION study, ⁶⁸Ga-PSMA-11 was used to determine the eligibility of patients with metastatic castration-resistant prostate cancer for treatment with ¹⁷⁷Lu-vipivotide tetraxetan (¹⁷⁷Lu-PSMA-617), based on predefined read criteria. This substudy aimed to investigate the interreader variability and intrareader reproducibility of visual assessments of ⁶⁸Ga-PSMA-11 PET/CT scans using the VISION read criteria and evaluate the agreement between read results for this and the VISION study. Methods: In VISION, ⁶⁸Ga-PSMA-11 PET/CT scans were centrally read as inclusion cases if they had at least 1 PSMA-positive lesion and no PSMA-negative lesions that fulfilled the exclusion criteria. In this substudy, 125 PET/CT scans (75 inclusion and 50 exclusion cases) were randomly selected from VISION and retrospectively assessed by 3 independent central readers. A random subset of 20 cases (12 inclusion and 8 exclusion cases) was recoded for assessment of intrareader reproducibility. Classification of cases as inclusion or exclusion cases was based on the VISION read criteria. Overall interreader variability was assessed by Fleiss κ-statistics, and pairwise variability and intrareader reproducibility were assessed by Cohen κ-statistics. Results: For interreader variability, the readers agreed on 77% of cases (overall average agreement rate, 0.85; Fleiss κ, 0.60 [95% CI, 0.50-0.70]). The pairwise agreement rate was 0.82, 0.88, and 0.84, and the corresponding Cohen κ was 0.54 (95% CI, 0.38-0.71), 0.67 (95% CI, 0.52-0.83), and 0.59 (95% CI, 0.43-0.75), respectively. For intrareader reproducibility, the agreement rate was 0.90, 0.90, and 0.95, and the corresponding Cohen κ was 0.78 (95% CI, 0.49-0.99), 0.76 (95% CI, 0.46-0.99), and 0.89 (95% CI, 0.67-0.99), respectively. The number of actual VISION inclusion cases out of the total number of cases scored as inclusion in this substudy was 71 of 93 (agreement rate, 0.76; 95% CI, 0.66-0.85) for reader 1, 70 of 88 (0.80; 0.70-0.87) for reader 2, and 73 of 96 (0.76; 0.66-0.84) for reader 3. All readers agreed on 66 of 75 VISION inclusion cases. Conclusion: Moderate-to-substantial interreader agreement and substantial-to-almost perfect intrareader reproducibility for ⁶⁸Ga-PSMA-11 PET/CT scan assessment using the VISION read criteria were observed. The read rules applied in VISION can be readily learned and demonstrate good reproducibility.

Synergistic Antitumor Activity of SH003 and Docetaxel via EGFR Signaling Inhibition in Non-Small Cell Lung Cancer

Epidermal growth factor receptor (EGFR) is overexpressed in lung cancer patients. Despite treatment with various EGFR tyrosine kinase inhibitors, recurrence and metastasis of lung cancer are inevitable. Docetaxel (DTX) is an effective conventional drug that is used to treat various cancers. Several researchers have studied the use of traditional herbal medicine in combination with docetaxel, to improve lung cancer treatment. SH003, a novel herbal mixture, exerts anticancer effects in different cancer cell types. Here, we aimed to investigate the apoptotic and anticancer effects of SH003 in combination with DTX, in human non-small-cell lung cancer (NSCLC). SH003, with DTX, induced apoptotic cell death, with increased expression of cleaved caspases and cleaved poly (ADP-ribose) polymerase in NSCLC cells. Moreover, SH003 and DTX induced the apoptosis of H460 cells via the suppression of the EGFR and signal transducer and activator of transcription 3 (STAT3) signaling pathways. In H460 tumor xenograft models, the administration of SH003 or docetaxel alone diminished tumor growth, and their combination effectively killed cancer cells, with increased expression of apoptotic markers and decreased expression of p-EGFR and p-STAT3. Collectively, the combination of SH003 and DTX may be a novel anticancer strategy to overcome the challenges that are associated with conventional lung cancer therapy.

Role of noncoding RNA in drug resistance of prostate cancer

Prostate cancer is one of the most prevalent forms of cancer around the world. Androgen-deprivation treatment and chemotherapy are the curative approaches used to suppress prostate cancer progression. However, drug resistance is extensively and hard to overcome even though remarkable progress has been made in recent decades. Noncoding RNAs, such as miRNAs, lncRNAs, and circRNAs, are a group of cellular RNAs which participate in various cellular processes and diseases. Recently, accumulating evidence has highlighted the vital role of non-coding RNA in the development of drug resistance in prostate cancer. In this review, we summarize the important roles of these three classes of noncoding RNA in drug resistance and the potential therapeutic applications in this disease.

δ-Tocopherol Enhances Docetaxel-Induced Growth Inhibition and Apoptosis in Ovarian Cancer SKOV3 Cells

Docetaxel is the first-line chemotherapeutic drug for ovarian cancer. However, its clinical use is limited owing to its serious side effects. Therefore, it is of great clinical significance to enhance the efficacy of docetaxel at lower doses in a less-toxic manner. In this study, we investigated whether δ-tocopherol could enhance the anti-tumor effects of docetaxel on ovarian cancer SKOV3 cells in vitro. For docetaxel and δ-tocopherol, IC50 values of 1.89 nM and 11.41 µM, respectively, were obtained, in SKOV3 cells. The combination of δ-tocopherol and docetaxel had a synergistic cell growth inhibition effect, with lower cell viability and more cell arrest at the S phase compared to either δ-tocopherol or docetaxel alone. In addition, the combination of δ-tocopherol and docetaxel had a synergistic cell apoptosis induction effect, with more apoptotic cells and reduced anti-apoptotic protein expression compared to either δ-tocopherol or docetaxel alone. Furthermore, we identified 3 hoursub genes (CAT, EP300, CREBBP), which predicted the prognosis of ovarian cancer, which correlated with δ-tocopherol and docetaxel. In conclusion, the combination of δ-tocopherol and docetaxel presented synergistic cell growth inhibition and cell apoptosis induction effects in SKOV3 cells at a low dose, which suggesting that δ-tocopherol could improve the serious side effects of docetaxel.

Association between the anticancer efficacy of cabazitaxel and toll-like receptor 4 mediating signaling pathways in metastatic castration-resistant prostate cancer cells

BACKGROUND

We evaluated the effect of cabazitaxel (CAB) as a third-line taxane on Toll-like receptor 4 (TLR4)-mediated signaling pathways, especially NF-κB activity, in metastatic castration-resistant prostate cancer (mCRPC) cells.

METHODS

CAB cytotoxicity was determined by WST-1 assay. To assess the relationship between CAB efficacy and TLR4 signaling pathways, RT-PCR, western blot and immunofluorescence analysis were performed. Additionally, CAB-mediated apoptotic cell death was assessed by Annexin V and RT-PCR analysis.

RESULTS

Our results demonstrated that CAB exerted considerably cytotoxic and apoptotic effects on PC-3 mCRPC cells (p < 0.05). CAB treatment altered TLR4 expression level in a dose-dependent manner. Furthermore, 1 nM CAB treatment significantly induced NF-κB activity through p65 nuclear localization and increased the expression level of caspase-3, Bax and p53. Interestingly, total apoptotic cell death and IRF3 protein levels were increased at 5 nM concentration of CAB despite a decrease in the levels of both NF-κB and pro-apoptotic genes.

CONCLUSIONS

Therefore, NF-κB activity may be a potential target for the efficacy of CAB in mCRPC cells.

Naturally occurring compounds as pancreatic cancer therapeutics

Naturally occurring small molecule compounds have long been in the spotlight of pancreatic cancer research as potential therapeutics to prevent cancer progression and sensitize chemoresistant tumors. The hope is that terminal pancreatic cancer patients receiving aggressive chemotherapy can benefit from an increase in treatment efficacy without adding further toxicity by way of utilizing natural compounds. While preclinical studies on a number of natural compounds, such as resveratrol, curcumin, rapalogs and cannabinoids, show promising preclinical results, little has translated into clinical practice, though a number of other compounds hold clinical potential. Nevertheless, recent advances in compound formulation may increase the clinical utility of these compounds.

Proscillaridin A induces apoptosis, inhibits STAT3 activation and augments doxorubicin toxicity in prostate cancer cells

Cardiac glycosides are natural compounds used for the treatment of congestive heart failure and cardiac arrhythmias. Recently, they have been reported to exhibit anticancer activity. Proscillaridin A (PSN-A), a cardiac glycoside constituent of Urginea maritima has been shown to exhibit anticancer activity. However, the cellular targets and anticancer mechanism of PSN-A in various cancers including prostate cancer remain largely unexplored. In the present study, we have shown that PSN-A inhibits proliferation and induces apoptosis in prostate cancer cells in a dose-dependent manner. Further mechanistic study have shown that anticancer activity of PSN-A in prostate cancer cells is associated with ROS generation, Bcl-2 family proteins modulation, mitochondrial membrane potential disruption and ultimately activation of caspase-3 and cleavage of PARP. Moreover, we found that PSN-A inhibits JAK2/STAT3 signaling and augments doxorubicin toxicity in prostate cancer cells. Of note, LNCaP cells were found to be more sensitive to PSN-A treatment as compared to DU145 cells. Taken together, the data provided first evidence of the anticancer activity and possible molecular mechanism of PSN-A in prostate cancer. Further study is needed to develop PSN-A into a potential lead compound for the treatment of prostate cancer.

Three-year Safety of Radium-223 Dichloride in Patients with Castration-resistant Prostate Cancer and Symptomatic Bone Metastases from Phase 3 Randomized Alpharadin in Symptomatic Prostate Cancer Trial

BACKGROUND

In Alpharadin in Symptomatic Prostate Cancer (ALSYMPCA) trial, radium-223 versus placebo prolonged overall survival with favorable safety in castration-resistant prostate cancer patients with symptomatic bone metastases. Long-term radium-223 monitoring underlies a comprehensive safety and risk/benefit assessment.

OBJECTIVE

To report updated ALSYMPCA safety, including long-term safety up to 3 yr after the first injection.

DESIGN, SETTING, AND PARTICIPANTS

Safety analyses from phase 3 randomized ALSYMPCA trial included patients receiving ≥1 study-drug injection (600 radium-223 and 301 placebo). Patients (405 radium-223 and 167 placebo) entered long-term safety follow-up starting 12 wk after the last study-drug injection, to 3 yr from the first injection. Forty-eight of 405 (12%) radium-223 and 12/167 (7%) placebo patients completed follow-up, with evaluations every 2 mo for 6 mo, then every 4 mo until 3 yr.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

All adverse events (AEs) were collected until 12 wk after the last injection; subsequently, only treatment-related AEs were collected. Additional long-term safety was assessed by development of acute myelogenous leukemia (AML), myelodysplastic syndrome (MDS), aplastic anemia, and secondary malignancies. Data analysis used descriptive statistics.

RESULTS AND LIMITATIONS

During treatment to 12 wk following the last injection, 564/600 (94%) radium-223 and 292/301 (97%) placebo patients had treatment-emergent AEs (TEAEs). Myelosuppression incidence was low. Grade 3/4 hematologic TEAEs in radium-223 and placebo groups were anemia (13% vs 13%), neutropenia (2% vs 1%), and thrombocytopenia (7% vs 2%). Ninety-eight of 600 (16%) radium-223 and 68/301 (23%) placebo patients experienced grade 5 TEAEs. Long-term follow-up showed no AML, MDS, or new primary bone cancer; secondary non-treatment-related malignancies occurred in four radium-223 and three placebo patients. One radium-223 patient had aplastic anemia 16 mo after the last injection. No other cases were observed. Limitations include short (3-yr) follow-up.

CONCLUSIONS

Final long-term safety ALSYMPCA analysis shows that radium-223 remained well tolerated, with low myelosuppression incidence and no new safety concerns.

PATIENT SUMMARY

Updated Alpharadin in Symptomatic Prostate Cancer (ALSYMPCA) trial findings show that radium-223 remained well tolerated during treatment and up to 3 yr after each patient's first injection.

Brefeldin A enhances docetaxel-induced growth inhibition and apoptosis in prostate cancer cells in monolayer and 3D cultures

Docetaxel is a commonly used chemotherapeutic drug for patients with late stage prostate cancer. However, serious side effect and drug resistance limit its clinical success. Brefeldin A is a 16-membered macrolide antibiotic from mangrove-derived Fungus Aspergillus sp. (9Hu), which exhibited potent cytotoxicity against human cancer cells. In the present study, we determined the effect of brefeldin A on docetaxel-induced growth inhibition and apoptosis in human prostate cancer PC-3 cells. Brefeldin A in combination with docetaxel inhibited the growth of PC-3 cells in monolayer and in three dimensional cultures. The combination also potently stimulated apoptosis in PC-3 cells as determined by propidium iodide staining and morphological assessment. Mechanistic studies showed that growth inhibition and apoptosis in PC-3 cells treated with brefeldin A and docetaxel were associated with decrease in the level of Bcl-2. The present study indicates that combined brefeldin A with docetaxel may represent a novel approach for improving the efficacy of docetaxel, and Bcl-2 may serve as a target for brefeldin A to enhance the effects of docetaxel chemotherapy.

Carbon nanomaterials sensitize prostate cancer cells to docetaxel and mitomycin C via induction of apoptosis and inhibition of proliferation

We have previously shown that carbon nanofibers (CNFs) and carbon nanotubes (CNTs) can sensitize prostate cancer (PCa) cells to platinum-based chemotherapeutics. In order to further verify this concept and to avoid a bias, the present study investigates the chemosensitizing potential of CNFs and CNTs to the conventional chemotherapeutics docetaxel (DTX) and mitomycin C (MMC), which have different molecular structures and mechanisms of action than platinum-based chemotherapeutics. DU-145 PCa cells were treated with DTX and MMC alone or in combination with the carbon nanomaterials. The impact of the monotreatments and the combinatory treatments on cellular function was then systematically analyzed by using different experimental approaches (viability, short-term and long-term proliferation, cell death rate). DTX and MMC alone reduced the viability of PCa cells to 94% and 68%, respectively, whereas a combined treatment with CNFs led to less than 30% remaining viable cells. Up to 17- and 7-fold higher DTX and MMC concentrations were needed in order to evoke a similar inhibition of viability as mediated by the combinatory treatments. In contrast, the dose of platinum-based chemotherapeutics could only be reduced by up to 3-fold by combination with carbon nanomaterials. Furthermore, combinatory treatments with CNFs led mostly to an additive inhibition of short- and long-term proliferation compared to the individual treatments. Also, higher cell death rates were observed in combinatory treatments than in monotreatments, e.g., a combination of MMC and CNFs more than doubled the cell death rate mediated by apoptosis. Combinations with CNTs showed a similar, but less pronounced impact on cellular functions. In summary, carbon nanomaterials in combination with DTX and MMC evoked additive to partly synergistic anti-tumor effects. CNFs and CNTs possess the ability to sensitize cancer cells to a wide range of structurally diverse chemotherapeutics and thus represent an interesting option for the development of multimodal cancer therapies. Co-administration of chemotherapeutics with carbon nanomaterials could result in a reduction of the chemotherapeutic dosage and thus limit systemic side effects.

Targeting Taxanes to Castration-Resistant Prostate Cancer Cells by Nanobubbles and Extracorporeal Shock Waves

To target taxanes to castration-resistant prostate cancer cells, glycol-chitosan nanobubbles loaded with paclitaxel and docetaxel were constructed. The loaded nanobubbles were then combined with Extracorporeal Shock Waves, acoustic waves widely used in urology and orthopedics, with no side effects. Nanobubbles, with an average diameter of 353.3 ± 15.5 nm, entered two different castration-resistant prostate cancer cells (PC3 and DU145) as demonstrated by flow cytometry and immunofluorescence. The shock waves applied increased the amount of intracellular nanobubbles. Loading nanobubbles with paclitaxel and docetaxel and combining them with shock waves generated the highest cytotoxic effects, resulting in a paclitaxel GI₅₀ reduction of about 55% and in a docetaxel GI₅₀ reduction of about 45% respectively. Combined treatment also affected cell migration. Paclitaxel-loaded nanobubbles and shock waves reduced cell migration by more than 85% with respect to paclitaxel alone; whereas docetaxel-loaded nanobubbles and shock waves reduced cell migration by more than 82% with respect to docetaxel alone. The present data suggest that nanobubbles can act as a stable taxane reservoir in castration-resistant prostate cancer cells and shock waves can further increase drug release from nanobubbles leading to higher cytotoxic and anti-migration effect.

Tubeimoside-1 induces oxidative stress-mediated apoptosis and G0/G1 phase arrest in human prostate carcinoma cells in vitro

AIM

Tubeimoside-1 (TBMS1), a triterpenoid saponin extracted from the Chinese herbal medicine Bolbostemma paniculatum (Maxim) Franquet (Cucurbitaceae), has shown anticancer activities in various cancer cell lines. The aim of this study was to investigate the anticancer activity and molecular targets of TBMS1 in human prostate cancer cells in vitro.

METHODS

DU145 and P3 human prostate cancer cells were treated with TBMS1. Cell viability and apoptosis were detected. ROS generation, mitochondrial membrane potential and cell cycle profile were examined. Western blotting was used to measure the expression of relevant proteins in the cells.

RESULTS

TBMS1 (5-100 μmol/L) significantly suppressed the viability of DU145 and P3 cells with IC50 values of approximately 10 and 20 μmol/L, respectively. Furthermore, TBMS1 dose-dependently induced apoptosis and cell cycle arrest at G0/G1 phase in DU145 and P3 cells. In DU145 cells, TBMS1 induced mitochondrial apoptosis, evidenced by ROS generation, mitochondrial dysfunction, endoplasmic reticulum stress, modulated Bcl-2 family protein and cleaved caspase-3, and activated ASK-1 and its downstream targets p38 and JNK. The G0/G1 phase arrest was linked to increased expression of p53 and p21 and decreased expression of cyclin E and cdk2. Co-treatment with Z-VAD-FMK (pan-caspase inhibitor) could attenuate TBMS1-induced apoptosis but did not prevent G0/G1 arrest. Moreover, co-treatment with NAC (ROS scavenger), SB203580 (p38 inhibitor), SP600125 (JNK inhibitor) or salubrinal (ER stress inhibitor) significantly attenuated TBMS1-induced apoptosis.

CONCLUSION

TBMS1 induces oxidative stress-mediated apoptosis in DU145 human prostate cancer cells in vitro via the mitochondrial pathway.

A Review of Paclitaxel and Novel Formulations Including Those Suitable for Use in Dogs

Paclitaxel is a commonly used chemotherapeutic agent with a broad spectrum of activity against cancers in humans. In 1992, paclitaxel was approved by the U.S. Food and Drug Administration (FDA) as Taxol(®) for use in advanced ovarian cancer. Two years later, it was approved for the treatment of metastatic breast cancer. Paclitaxel was originally isolated from the bark of the Pacific yew tree, Taxus brevifolia in 1971. Taxanes are a family of microtubule inhibitors. As a member of this family, paclitaxel suppresses spindle microtubule dynamics. This activity results in the blockage of the metaphase-anaphase transitions, and ultimately in the inhibition of mitosis, and induction of apoptosis in a wide spectrum of cancer cells. Additional anticancer activities of paclitaxel have been defined that are independent of these effects on the microtubules and may include the suppression of cell proliferation as well as antiangiogenic effects. Based on its targeting of a fundamental feature of the cancer phenotype, the mitotic complex, it is not surprising that paclitaxel has been found to be active in a wide variety of cancers in humans. This review summarizes the evidence in support of paclitaxel's broad anticancer activity and introduces the rationale for, and the progress in development of novel formulations of paclitaxel that may preferentially target cancers and that are not associated with the risks for hypersensitivity in dogs. Of note, a novel nanoparticle formulation of paclitaxel that substantially limits hypersensitivity was recently given conditional approval by the FDA Center for Veterinary Medicine for use in dogs with resectable and nonresectable squamous cell carcinoma and nonresectable stage III, IV and V mammary carcinoma.

A new approach to produce drug nanosuspensions CO2-assisted effervescence to produce drug nanosuspensions

The exploration of a simple and robust approach to produce nanosuspensions is a meaningful attempt for clinical translation. CO2-assisted effervescence was firstly developed to prepare nanosuspensions and was found to be easy for scale-up. Drug nanosuspensions were easily obtained by adding aqueous carbonate to the pre-treated mixture of drug, stabilizer and organic acid. The burst of CO2 bubbles resulted from the acid-base reaction insert a micro gas bubble smashing and mixing effect to the formation of nanosuspensions, leading to smaller sizes and a refined size distribution. We successfully prepared nanosuspensions with twelve structurally diverse drugs. Alternatively, solid carbonate blended with the mixture, allowing for later addition of water, also facilitates the formation of amorphous nanosuspensions. We defined this approach as in situ nanoamorphization (ISN). Intensive in vitro and in vivo investigations for itraconazole and cabazitaxel nanosuspensions validate the availability for administration.

A Randomised Phase II Trial Comparing Docetaxel Plus Prednisone with Docetaxel Plus Prednisone Plus Low-Dose Cyclophosphamide in Castration-Resistant Prostate Cancer

BACKGROUND

Docetaxel plus prednisone is a standard treatment for castration-resistant prostate cancer. Cyclophosphamide may be an effective combination partner.

METHODS

This randomised, multicentre, phase II trial compared the combination therapy of docetaxel plus prednisone plus cyclophosphamide with the standard therapy of docetaxel plus prednisone.

RESULTS

Thirty-three patients received six 3-week treatment cycles (in total 171 cycles). During treatment, an adequate decline in prostate-specific antigen was seen in both groups (p = 0.068) without between-group differences (p = 0.683). No relevant differences between within-group changes were observed for blood pressure, weight, pain score, laboratory variables or quality of life. There were no serious side effects apart from leucopenia requiring treatment (docetaxel + prednisone + cyclophosphamide arm) and no drug-related withdrawals; all three fatalities were considered to be cancer related.

CONCLUSIONS

The oncological effectiveness and tolerability of docetaxel plus prednisone were supported; an additional effect of cyclophosphamide was not detected. However, the small number of patients and short observation period restrict the generalisability of the results.

Impact of beta-blockers on prostate cancer mortality: a meta-analysis of 16,825 patients

Introduction

Increasing evidence suggests that beta-blocker use might be associated with reduced mortality in prostate cancer patients. To provide a quantitative assessment of this association, we pooled data available to examine the association between beta-blocker use and mortality of prostate cancer.

Methods

We identified studies by a literature search of MEDLINE (from 1 January 1966) and EMBASE (from 1 January 1974), through 10 September 2014, and by searching the reference lists of pertinent articles. Two authors independently screened and reviewed the eligibility of each study. The primary outcomes were prostate cancer-specific mortality and all-cause mortality.

Results

A total of four studies including 16,825 patients were included in this meta-analysis. Analysis of all studies showed that beta-blocker use was associated with reduced prostate cancer-specific mortality (hazard ratio =0.85, 95% confidence interval =0.77–0.94), without any heterogeneity between studies (Q=3.59, I2=16.5%, P=0.309). However, we observed no association with all-cause mortality (hazard ratio =0.97, 95% confidence interval =0.90–1.04). There was also no evidence of the presence of significant heterogeneity between the four studies (Q=2.48, I2=0.0%, P=0.480).

Conclusion

These findings indicate that beta-blocker use was associated with reduced cancer-specific mortality among prostate cancer patients taking beta-blockers.

Exploitation of the Androgen Receptor to Overcome Taxane Resistance in Advanced Prostate Cancer

Prostate cancer is a tumor addicted to androgen receptor (AR) signaling, even in its castration resistant state, and recently developed antiandrogen therapies including Abiraterone acetate and enzalutamide effectively target the androgen signaling axis, but there is ultimately recurrence to lethal disease. Development of advanced castration-resistant prostate cancer (CRPC) is a biological consequence of lack of an apoptotic response of prostate tumor cells to androgen ablation. Taxanes represent the major clinically relevant chemotherapy for the treatment of patients with metastatic CRPC; unfortunately, they do not deliver a cure but an extension of overall survival. First-generation taxane chemotherapies, Docetaxel (Taxotere), effectively target the cytoskeleton by stabilizing the interaction of β-tubulin subunits of microtubules preventing depolymerization, inducing G2M arrest and apoptosis. Shifting the current paradigm is a growing evidence to indicate that Docetaxel can effectively target the AR signaling axis by blocking its nuclear translocation and transcriptional activity in androgen-sensitive and castration-resistant prostate cancer cells, implicating a new mechanism of cross-resistance between microtubule-targeting chemotherapy and antiandrogen therapies. More recently, Cabazitaxel has emerged as a second-line taxane chemotherapy capable of conferring additional survival benefit to patients with CRPC previously treated with Docetaxel or in combination with antiandrogens. Similar to Docetaxel, Cabazitaxel induces apoptosis and G2M arrest; in contrast to Docetaxel, it sustains AR nuclear accumulation although it reduces the overall AR levels and FOXO1 expression. Cabazitaxel treatment also leads to downregulation of the microtubule-depolymerizing mitotic kinesins, MCAK, and HSET, preventing their ability to depolymerize microtubules and thus enhancing sensitivity to taxane treatment. The molecular mechanisms underlying taxane resistance involve mutational alterations in the tubulin subunits, microtubule dynamics, phenotyping programming of the epithelial-to-mesenchymal transition landscape, and the status of AR activity. This chapter discusses the mechanisms driving the therapeutic resistance of taxanes and antiandrogen therapies in CRPC, and the role of AR in potential interventions toward overcoming such resistance in patients with advanced metastatic disease.

USP11-dependent selective cIAP2 deubiquitylation and stabilization determine sensitivity to Smac mimetics

Given their crucial role in apoptosis suppression, inhibitor of apoptosis proteins (IAPs) have recently become attractive targets for cancer therapy. Here, we report that cellular IAP2 (cIAP2) is specifically stabilized in several cancer cell lines, leading to resistance to Smac mimetics, such as BV6 and birinapant. In particular, our results showed that cIAP2 depletion, but not cIAP1 depletion, sensitized cancer cells to Smac mimetic-induced apoptosis. Ubiquitin-specific protease 11 (USP11) is a deubiquitylase that directly stabilizes cIAP2. USP11 overexpression is frequently found in colorectal cancer and melanoma and is correlated with poor survival. In our study, cancer cell lines expressing high levels of USP11 exhibited strong resistance to Smac mimetic-induced cIAP2 degradation. Furthermore, USP11 downregulation sensitized these cells to apoptosis induced by TRAIL and BV6 and suppressed tumor growth in a xenograft model. Finally, the TNFα/JNK pathway induced USP11 expression and maintained cIAP2 stability, suggesting an alternative TNFα-dependent cell survival pathway. Collectively, our data suggest that USP11-stabilized cIAP2 may serve as a barrier against IAP-targeted clinical approaches.