Skp2 E3 ligase is overexpressed in numerous human cancers and plays a critical role in cell-cycle progression, senescence, metabolism, cancer progression, and metastasis. In the present study, we ...identified a specific Skp2 inhibitor using high-throughput in silico screening of large and diverse chemical libraries. This Skp2 inhibitor selectively suppresses Skp2 E3 ligase activity, but not activity of other SCF complexes. It also phenocopies the effects observed upon genetic Skp2 deficiency, such as suppressing survival and Akt-mediated glycolysis and triggering p53-independent cellular senescence. Strikingly, we discovered a critical function of Skp2 in positively regulating cancer stem cell populations and self-renewal ability through genetic and pharmacological approaches. Notably, Skp2 inhibitor exhibits potent antitumor activities in multiple animal models and cooperates with chemotherapeutic agents to reduce cancer cell survival. Our study thus provides pharmacological evidence that Skp2 is a promising target for restricting cancer stem cell and cancer progression.
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•Integrated computational approaches identify a specific Skp2 inhibitor•The Skp2 inhibitor selectively impairs Skp2 activity and functions•Skp2 inactivation restricts cancer stemness and potentiates chemotherapy sensitivity•The Skp2 inhibitor exhibits potent antitumor activity
A selective Skp2 inhibitor identified through a virtual chemical screen suppresses cancer stem cell renewal and cancer progression, establishing Skp2 as a promising target for cancer treatment.
Summary Background Abiraterone acetate improved overall survival in metastatic castration-resistant prostate cancer at a preplanned interim analysis of the COU-AA-301 double-blind, placebo-controlled ...phase 3 study. Here, we present the final analysis of the study before crossover from placebo to abiraterone acetate (after 775 of the prespecified 797 death events). Methods Between May 8, 2008, and July 28, 2009, this study enrolled 1195 patients at 147 sites in 13 countries. Patients were eligible if they had metastatic castration-resistant prostate cancer progressing after docetaxel. Patients were stratified according to baseline Eastern Cooperative Oncology Group (ECOG) performance status, worst pain over the past 24 h on the Brief Pain Inventory-Short Form, number of previous chemotherapy regimens, and type of progression. Patients were randomly assigned (ratio 2:1) to receive either abiraterone acetate (1000 mg, once daily and orally) plus prednisone (5 mg, orally twice daily) or placebo plus prednisone with a permuted block method via an interactive web response system. The primary endpoint was overall survival, analysed in the intention-to-treat population. This study is registered with ClinicalTrials.gov , number NCT00638690. Findings Of the 1195 eligible patients, 797 were randomly assigned to receive abiraterone acetate plus prednisone (abiraterone group) and 398 to receive placebo plus prednisone (placebo group). At median follow-up of 20·2 months (IQR 18·4–22·1), median overall survival for the abiraterone group was longer than in the placebo group (15·8 months 95% CI 14·8–17·0 vs 11·2 months 10·4–13·1; hazard ratio HR 0·74, 95% CI 0·64–0·86; p<0·0001). Median time to PSA progression (8·5 months, 95% CI 8·3–11·1, in the abiraterone group vs 6·6 months, 5·6–8·3, in the placebo group; HR 0·63, 0·52–0·78; p<0·0001), median radiologic progression-free survival (5·6 months, 5·6–6·5, vs 3·6 months, 2·9–5·5; HR 0·66, 0·58–0·76; p<0·0001), and proportion of patients who had a PSA response (235 29·5% of 797 patients vs 22 5·5% of 398; p<0·0001) were all improved in the abiraterone group compared with the placebo group. The most common grade 3–4 adverse events were fatigue (72 9% of 791 patients in the abiraterone group vs 41 10% of 394 in the placebo group), anaemia (62 8% vs 32 8%), back pain (56 7% vs 40 10%), and bone pain (51 6% vs 31 8%). Interpretation This final analysis confirms that abiraterone acetate significantly prolongs overall survival in patients with metastatic castration-resistant prostate cancer who have progressed after docetaxel treatment. No new safety signals were identified with increased follow-up. Funding Janssen Research & Development.
Summary Background Abiraterone acetate plus prednisone significantly improved radiographic progression-free survival compared with placebo plus prednisone in men with chemotherapy-naive ...castration-resistant prostate cancer at the interim analyses of the COU-AA-302 trial. Here, we present the prespecified final analysis of the trial, assessing the effect of abiraterone acetate plus prednisone on overall survival, time to opiate use, and use of other subsequent therapies. Methods In this placebo-controlled, double-blind, randomised phase 3 study, 1088 asymptomatic or mildly symptomatic patients with chemotherapy-naive prostate cancer stratified by Eastern Cooperative Oncology performance status (0 vs 1) were randomly assigned with a permuted block allocation scheme via a web response system in a 1:1 ratio to receive either abiraterone acetate (1000 mg once daily) plus prednisone (5 mg twice daily; abiraterone acetate group) or placebo plus prednisone (placebo group). Coprimary endpoints were radiographic progression-free survival and overall survival analysed in the intention-to-treat population. The study is registered with ClinicalTrials.gov , number NCT00887198. Findings At a median follow-up of 49·2 months (IQR 47·0–51·8), 741 (96%) of the prespecified 773 death events for the final analysis had been observed: 354 (65%) of 546 patients in the abiraterone acetate group and 387 (71%) of 542 in the placebo group. 238 (44%) patients initially receiving prednisone alone subsequently received abiraterone acetate plus prednisone as crossover per protocol (93 patients) or as subsequent therapy (145 patients). Overall, 365 (67%) patients in the abiraterone acetate group and 435 (80%) in the placebo group received subsequent treatment with one or more approved agents. Median overall survival was significantly longer in the abiraterone acetate group than in the placebo group (34·7 months 95% CI 32·7–36·8 vs 30·3 months 28·7–33·3; hazard ratio 0·81 95% CI 0·70–0·93; p=0·0033). The most common grade 3–4 adverse events of special interest were cardiac disorders (41 8% of 542 patients in the abiraterone acetate group vs 20 4% of 540 patients in the placebo group), increased alanine aminotransferase (32 6% vs four <1%), and hypertension (25 5% vs 17 3%). Interpretation In this randomised phase 3 trial with a median follow-up of more than 4 years, treatment with abiraterone acetate prolonged overall survival compared with prednisone alone by a margin that was both clinically and statistically significant. These results further support the favourable safety profile of abiraterone acetate in patients with chemotherapy-naive metastatic castration-resistant prostate cancer. Funding Janssen Research & Development.
The signaling mechanisms between prostate cancer cells and infiltrating immune cells may illuminate novel therapeutic approaches. Here, utilizing a prostate adenocarcinoma model driven by loss of ...Pten and Smad4, we identify polymorphonuclear myeloid-derived suppressor cells (MDSC) as the major infiltrating immune cell type, and depletion of MDSCs blocks progression. Employing a novel dual reporter prostate cancer model, epithelial and stromal transcriptomic profiling identified CXCL5 as a cancer-secreted chemokine to attract CXCR2-expressing MDSCs, and, correspondingly, pharmacologic inhibition of CXCR2 impeded tumor progression. Integrated analyses identified hyperactivated Hippo-YAP signaling in driving CXCL5 upregulation in cancer cells through the YAP-TEAD complex and promoting MDSC recruitment. Clinicopathologic studies reveal upregulation and activation of YAP1 in a subset of human prostate tumors, and the YAP1 signature is enriched in primary prostate tumor samples with stronger expression of MDSC-relevant genes. Together, YAP-driven MDSC recruitment via heterotypic CXCL5-CXCR2 signaling reveals an effective therapeutic strategy for advanced prostate cancer.
We demonstrate a critical role of MDSCs in prostate tumor progression and discover a cancer cell nonautonomous function of the Hippo-YAP pathway in regulation of CXCL5, a ligand for CXCR2-expressing MDSCs. Pharmacologic elimination of MDSCs or blocking the heterotypic CXCL5-CXCR2 signaling circuit elicits robust antitumor responses and prolongs survival.
Abiraterone has been approved as second-line chemotherapy in patients with metastatic castration-resistant prostate cancer. This study shows significant improvement in progression-free survival with ...abiraterone as first-line chemotherapy in these patients.
Metastatic castration-resistant prostate cancer, defined by tumor growth despite a testosterone level of less than 50 ng per deciliter (1.7 nmol per liter), causes approximately 258,400 deaths annually worldwide.
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Death of patients with this condition, which typically occurs within 24 to 48 months after the onset of castration resistance, is commonly preceded by a sequence of landmark events associated with deterioration of overall health and worsening symptoms (Figure S1 in the Supplementary Appendix, available with the full text of this article at NEJM.org).
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Among the treatment options for patients with metastatic castration-resistant prostate cancer who have not undergone chemotherapy . . .
Abstract Background Enzalutamide is a novel antiandrogen with proven efficacy in metastatic castration-resistant prostate cancer (mCRPC). Objective To evaluate enzalutamide's effects on cancer and on ...androgens in blood and bone marrow, and associate these with clinical observations. Design, setting, and participants In this prospective phase 2 study, 60 patients with bone mCRPC received enzalutamide 160 mg orally daily and had transilial bone marrow biopsies before treatment and at 8 wk of treatment. Outcome measurements and statistical analysis Androgen signaling components (androgen receptor AR, AR splice variant 7 (ARV7), v-ets avian erythroblastosis virus E26 oncogene homolog ERG, cytochrome P450, family 17, subfamily A, polypeptide 1 CYP17) and molecules implicated in mCRPC progression (phospho-Met, phospho-Src, glucocorticoid receptor, Ki67) were assessed by immunohistochemistry; testosterone, cortisol, and androstenedione concentrations were assessed by liquid chromatography–tandem mass spectrometry; AR copy number was assessed by real-time polymerase chain reaction. Descriptive statistics were applied. Results and limitations Median time to treatment discontinuation was 22 wk (95% confidence interval, 19.9–29.6). Twenty-two (37%) patients exhibited primary resistance to enzalutamide, discontinuing treatment within 4 mo. Maximal prostate-specific antigen (PSA) decline ≥50% and ≥90% occurred in 27 (45%) and 13 (22%) patients, respectively. Following 8 wk of treatment, bone marrow and circulating testosterone levels increased. Pretreatment tumor nuclear AR overexpression (>75%) and CYP17 (>10%) expression were associated with benefit ( p = 0.018). AR subcellular localization shift from the nucleus was confirmed in eight paired samples (with PSA decline) of 23 evaluable paired samples. Presence of an ARV7 variant was associated with primary resistance to enzalutamide ( p = 0.018). Limited patient numbers warrant further validation. Conclusions The observed subcellular shift of AR from the nucleus and increased testosterone concentration provide the first evidence in humans that enzalutamide suppresses AR signaling while inducing an adaptive feedback. Persistent androgen signaling in mCRPC was predictive of benefit and ARV7 was associated with primary resistance. Patient summary We report a first bone biopsy study in metastatic prostate cancer in humans that searched for predictors of outcome of enzalutamide therapy. Benefit is linked to a pretreatment androgen-signaling signature. Trial registration ClinicalTrials.gov identifier NCT01091103.
Persistent androgen signaling is implicated in castrate-resistant prostate cancer (CRPC) progression. This study aimed to evaluate androgen signaling in bone marrow-infiltrating cancer and ...testosterone in blood and bone marrow and to correlate with clinical observations.
This was an open-label, observational study of 57 patients with bone-metastatic CRPC who underwent transiliac bone marrow biopsy between October 2007 and March 2010. Patients received oral abiraterone acetate (1 g) once daily and prednisone (5 mg) twice daily. Androgen receptor (AR) and CYP17 expression were assessed by immunohistochemistry, testosterone concentration by mass spectrometry, AR copy number by polymerase chain reaction, and TMPRSS2-ERG status by fluorescent in situ hybridization in available tissues.
Median overall survival was 555 days (95% CI, 440 to 965+ days). Maximal prostate-specific antigen decline ≥ 50% occurred in 28 (50%) of 56 patients. Homogeneous, intense nuclear expression of AR, combined with ≥ 10% CYP17 tumor expression, was correlated with longer time to treatment discontinuation (> 4 months) in 25 patients with tumor-infiltrated bone marrow samples. Pretreatment CYP17 tumor expression ≥ 10% was correlated with increased bone marrow aspirate testosterone. Blood and bone marrow aspirate testosterone concentrations declined to less than picograms-per-milliliter levels and remained suppressed at progression.
The observed pretreatment androgen-signaling signature is consistent with persistent androgen signaling in CRPC bone metastases. This is the first evidence that abiraterone acetate achieves sustained suppression of testosterone in both blood and bone marrow aspirate to less than picograms-per-milliliter levels. Potential admixture of blood with bone marrow aspirate limits our ability to determine the origin of measured testosterone.
In this study, abiraterone acetate inhibited androgen synthesis and prolonged survival by 4 months among men with castration-resistant prostate cancer that had progressed with docetaxel chemotherapy.
...For the past 70 years, depleting or blocking the action of androgens has been the standard of care for men with advanced prostate cancer.
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Androgen deprivation results in a decrease in the concentration of prostate-specific antigen (PSA) as well as tumor regression and relief of symptoms in most patients, but the response to treatment is not durable in patients with advanced cancer, and with time, PSA concentrations increase, indicating reactivated androgen-receptor signaling and a transition to a castration-resistant state that is invariably fatal.
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Many endocrine therapies have been evaluated in these patients, but none have prolonged survival.
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Three nonhormonal systemic . . .
Cabozantinib (XL184), an oral inhibitor of multiple receptor tyrosine kinases such as MET and VEGFR2, was evaluated in a phase II nonrandomized expansion study in castration-resistant prostate cancer ...(CRPC).
Patients received open-label cabozantinib at daily starting doses of 100 mg or 40 mg until disease progression or unacceptable toxicity. The primary end point was bone scan response, defined as ≥ 30% reduction in bone scan lesion area. Other efficacy end points included overall survival, pain, analgesic use, and biomarkers.
One hundred forty-four patients sequentially enrolled in either a 100-mg (n = 93) or 40-mg (n = 51) study cohort. Ninety-one patients (63%) had a bone scan response, often by week 6. Treatment resulted in clinically meaningful pain relief (57% of patients) and reduction or discontinuation of narcotic analgesics (55% of patients), as well as improvements in measurable soft tissue disease, circulating tumor cells, and bone biomarkers. Improvements in each of these outcomes were observed in both cohorts: bone scan response in 73% and 45%, respectively; reductions in measurable soft tissue disease in 80% and 79%, respectively. Median overall survival was 10.8 months for the entire population. Most common grade 3 or 4 adverse events were fatigue (22%) and hypertension (14%). Fewer dose reductions because of toxicity were required in the 40-mg group.
The evidence suggests that cabozantinib has clinically meaningful activity in CRPC. Cabozantinib resulted in improvements in bone scans, pain, analgesic use, measurable soft tissue disease, circulating tumor cells, and bone biomarkers. Taken together, these phase II observations warrant further development of cabozantinib in prostate cancer.
Advances in prostate cancer lag behind other tumor types partly due to the paucity of models reflecting key milestones in prostate cancer progression. Therefore, we develop clinically relevant ...prostate cancer models.
Since 1996, we have generated clinically annotated patient-derived xenografts (PDXs; the MDA PCa PDX series) linked to specific phenotypes reflecting all aspects of clinical prostate cancer.
We studied two cell line-derived xenografts and the first 80 PDXs derived from 47 human prostate cancer donors. Of these, 47 PDXs derived from 22 donors are working models and can be expanded either as cell lines (MDA PCa 2a and 2b) or PDXs. The histopathologic, genomic, and molecular characteristics (androgen receptor, ERG, and
loss) maintain fidelity with the human tumor and correlate with published findings. PDX growth response to mouse castration and targeted therapy illustrate their clinical utility. Comparative genomic hybridization and sequencing show significant differences in oncogenic pathways in pairs of PDXs derived from different areas of the same tumor. We also identified a recurrent focal deletion in an area that includes the speckle-type POZ protein-like (
) gene in PDXs derived from seven human donors of 28 studied (25%).
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paralog, and
mutations define a molecular subclass of prostate cancer.
deletions are found in 7% of The Cancer Genome Atlas prostate cancers, which suggests that our cohort is a reliable platform for targeted drug development.
The MDA PCa PDX series is a dynamic resource that captures the molecular landscape of prostate cancers progressing under novel treatments and enables optimization of prostate cancer-specific, marker-driven therapy.
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