Mediator kinase inhibition reverses castration resistance of advanced prostate cancer.

Mediator kinases CDK19 and CDK8, pleiotropic regulators of transcriptional reprogramming, are differentially regulated by androgen signaling, but both kinases are upregulated in castration-resistant prostate cancer (CRPC). Genetic or pharmacological inhibition of CDK8 and CDK19 reverses the castration-resistant phenotype and restores the sensitivity of CRPC xenografts to androgen deprivation in vivo. Prolonged CDK8/19 inhibitor treatment combined with castration not only suppressed the growth of CRPC xenografts but also induced tumor regression and cures. Transcriptomic analysis revealed that Mediator kinase inhibition amplified and modulated the effects of castration on gene expression, disrupting CRPC adaptation to androgen deprivation. Mediator kinase inactivation in tumor cells also affected stromal gene expression, indicating that Mediator kinase activity in CRPC molded the tumor microenvironment. The combination of castration and Mediator kinase inhibition downregulated the MYC pathway, and Mediator kinase inhibition suppressed a MYC-driven CRPC tumor model even without castration. CDK8/19 inhibitors showed efficacy in patient-derived xenograft models of CRPC, and a gene signature of Mediator kinase activity correlated with tumor progression and overall survival in clinical samples of metastatic CRPC. These results indicate that Mediator kinases mediated androgen-independent in vivo growth of CRPC, supporting the development of CDK8/19 inhibitors for the treatment of this presently incurable disease.

Overall Survival and Updated Results for Sunitinib Compared With Interferon Alfa in Patients With Metastatic Renal Cell Carcinoma.

PURPOSE: A randomized, phase III trial demonstrated superiority of sunitinib over interferon alfa (IFN-α) in progression-free survival (primary end point) as first-line treatment for metastatic renal cell carcinoma (RCC). Final survival analyses and updated results are reported. PATIENTS AND METHODS: Seven hundred fifty treatment-naïve patients with metastatic clear cell RCC were randomly assigned to sunitinib 50 mg orally once daily on a 4 weeks on, 2 weeks off dosing schedule or to IFN-α 9 MU subcutaneously thrice weekly. Overall survival was compared by two-sided log-rank and Wilcoxon tests. Progression-free survival, response, and safety end points were assessed with updated follow-up. RESULTS: Median overall survival was greater in the sunitinib group than in the IFN-α group (26.4 v 21.8 months, respectively; hazard ratio [HR] = 0.821; 95% CI, 0.673 to 1.001; P = .051) per the primary analysis of unstratified log-rank test (P = .013 per unstratified Wilcoxon test). By stratified log-rank test, the HR was 0.818 (95% CI, 0.669 to 0.999; P = .049). Within the IFN-α group, 33% of patients received sunitinib, and 32% received other vascular endothelial growth factor-signaling inhibitors after discontinuation from the trial. Median progression-free survival was 11 months for sunitinib compared with 5 months for IFN-α (P < .001). Objective response rate was 47% for sunitinib compared with 12% for IFN-α (P < .001). The most commonly reported sunitinib-related grade 3 adverse events included hypertension (12%), fatigue (11%), diarrhea (9%), and hand-foot syndrome (9%). CONCLUSION: Sunitinib demonstrates longer overall survival compared with IFN-α plus improvement in response and progression-free survival in the first-line treatment of patients with metastatic RCC. The overall survival highlights an improved prognosis in patients with RCC in the era of targeted therapy.

Predicting Response of Triple-Negative Breast Cancer to Neoadjuvant Chemotherapy Using a Deep Convolutional Neural Network-Based Artificial Intelligence Tool.

PURPOSE: Achieving a pathological complete response (pCR) to neoadjuvant chemotherapy (NAC) is associated with improved patient outcomes in triple-negative breast cancer (TNBC). Currently, there are no validated predictive biomarkers for the response to NAC in TNBC. We developed and validated a deep convolutional neural network-based artificial intelligence (AI) model to predict the response of TNBC to NAC. MATERIALS AND METHODS: Whole-slide images (WSIs) of hematoxylin and eosin-stained core biopsies from 165 (pCR in 60 and non-pCR in 105) and 78 (pCR in 31 and non-pCR in 47) patients with TNBC were used to train and validate the model. The model extracts morphometric features from WSIs in an unsupervised manner, thereby generating clusters of morphologically similar patterns. Downstream ranking of clusters provided regions of interest and morphometric scores; a low score close to zero and a high score close to one represented a high or low probability of response to NAC. RESULTS: The predictive ability of AI score for the entire cohort of 78 patients with TNBC ascertained by receiver operating characteristic analysis demonstrated an area under the curve (AUC) of 0.75. The AUC for stages I, II, and III disease were 0.88, 0.73, and 0.74, respectively. Using a cutoff value of 0.35, the positive predictive value of the AI score for pCR was 73.7%, and the negative predictive value was 76.2% for non-pCR patients. CONCLUSION: To our knowledge, this study is the first to demonstrate the use of an AI tool on digitized hematoxylin and eosin-stained tissue images to predict the response to NAC in patients with TNBC with high accuracy. If validated in subsequent studies, these results may serve as an ancillary aid for individualized therapeutic decisions in patients with TNBC.

A Novel Artificial Intelligence-Powered Method for Prediction of Early Recurrence of Prostate Cancer After Prostatectomy and Cancer Drivers.

PURPOSE: To develop a novel artificial intelligence (AI)-powered method for the prediction of prostate cancer (PCa) early recurrence and identification of driver regions in PCa of all Gleason Grade Group (GGG). MATERIALS AND METHODS: Deep convolutional neural networks were used to develop the AI model. The AI model was trained on The Cancer Genome Atlas Prostatic Adenocarcinoma (TCGA-PRAD) whole slide images (WSI) and data set (n = 243) to predict 3-year biochemical recurrence after radical prostatectomy (RP) and was subsequently validated on WSI from patients with PCa (n = 173) from the University of Wisconsin-Madison. RESULTS: Our AI-powered platform can extract visual and subvisual morphologic features from WSI to identify driver regions predictive of early recurrence of PCa (regions of interest [ROIs]) after RP. The ROIs were ranked with AI-morphometric scores, which were prognostic for 3-year biochemical recurrence (area under the curve [AUC], 0.78), which is significantly better than the GGG overall (AUC, 0.62). The AI-morphometric scores also showed high accuracy in the prediction of recurrence for low- or intermediate-risk PCa-AUC, 0.76, 0.84, and 0.81 for GGG1, GGG2, and GGG3, respectively. These patients could benefit the most from timely adjuvant therapy after RP. The predictive value of the high-scored ROIs was validated by known PCa biomarkers studied. With this focused biomarker analysis, a potentially new STING pathway-related PCa biomarker-TMEM173-was identified. CONCLUSION: Our study introduces a novel approach for identifying patients with PCa at risk for early recurrence regardless of their GGG status and for identifying cancer drivers for focused evolution-aware novel biomarker discovery.

Prostate cancer cells survive anti-androgen and mitochondrial metabolic inhibitors by modulating glycolysis and mitochondrial metabolic activities.

BACKGROUND: Most cancer cells are more glycolytic even under aerobic conditions compared with their normal counterparts. Recent evidence of tumor cell metabolism, however, shows that some tumors also increase mitochondrial oxidative phosphorylation (ox-phos) at some disease states during progression and/or development of drug resistance. Our data show that anti-androgen enzalutamide (ENZA) resistant prostate cancer (PCa) cells use more mitochondrial metabolism leading to higher ox-phos as compared to the ENZA-sensitive cells and can become vulnerable to mitochondrial metabolism targeted therapies. METHODS: Seahorse assay, mass spectrometry and high resolution fluorescence confocal microscopy coupled with image analysis has been used to compare mitochondrial metabolism in ENZA-treated and -untreated anti-androgen-sensitive LNCaP and -resistant C4-2, CWR22ν1, and PCa2b cells. Ex vivo fluorescence microscopy and image analysis has been standardized to monitor mitochondrial electron transport (ETS) activity that likely increases ox-phos in circulating tumor cells (CTCs) isolated fom patients undergoing AR-targeted therapies. RESULTS: Our data show that PCa cells that are resistant to anti-androgen ENZA switch from glycolysis to ox-phos leading to an increased ETS activity. ENZA pretreated cells are more vulnerable to ETS component complex I inhibitor IACS-010759 (IACS) and mitochondrial glutaminase inhibitor CB-839 that reduces glutamate supply to tricarboxylic acid cycle. CTCs isolated from 6 of 20 patient blood samples showed relatively higher ETS activity than the rest of the patients. All six patients have developed ENZA resistance within less than 6 months of the sample collection. CONCLUSION: The enhanced growth inhibitory effects of mitochondrial metabolic inhibitors IACS and CB-839 in ENZA pretreated PCa cells provides a rationale for designing a drug combination trial. Patients can be selected for such trials by monitoring the mitochondrial ETS activities in their CTCs to maximize success.

Phase 2 Study of Weekly Paclitaxel Plus Estramustine in Metastatic Hormone-Refractory Prostate Carcinoma: ECOG-ACRIN Cancer Research Group (E1898) Trial.

INTRODUCTION: This multicenter phase 2 study assessed the combination of estramustine and weekly paclitaxel with metastatic castration-resistant prostate cancer (CRPC). PATIENTS AND METHODS: We enrolled 77 patients who had received no prior chemotherapy for CRPC between 1998 and 2000; a total of 74 subjects were eligible for the study. Each 8-week cycle included paclitaxel 90 mg/m2 provided intravenously weekly for 6 weeks, followed by 2 weeks off therapy and oral estramustine 280 mg twice daily for 3 days beginning 24 hours before the first dose of paclitaxel. The primary end point was rate of objective or prostate-specific antigen (PSA) response at 16 weeks. A 50% response rate was considered of further interest. RESULTS: Eligible patients received a median of 3 cycles (range, 1-10 cycles). The response rate among patients with measurable disease was 34% (95% confidence interval [CI], 19-52). The PSA response rate was 58% (95% CI, 47-70). Clinical benefit rate was 45% (95% CI, 33-57). The median progression-free survival was 5.9 months (95% CI, 4.4-6.7). The median overall survival was 17.6 months (95% CI, 14.6-20.8). The most common clinical grade 3/4 toxicities were fatigue (14%) and sensory neuropathy (7%). Grade 3/4 hematologic toxicities included lymphopenia (21%) and anemia (9%). There was one toxicity-related death. Quality-of-life scores improved by week 8, but the change was not statistically significant. CONCLUSION: The combination has activity defined by PSA declines in CRPC but did not meet the protocol-specified end point for efficacy as defined by objective response rate. Since this study was conducted, more effective, better-tolerated regimens have been developed.

Assessment of adherence and relative dose intensity with oral chemotherapy in oncology clinical trials at an academic medical center.

Background/Aims Oral chemotherapy is increasingly utilized leaving the patient responsible for self-administering an often complex regimen where adverse effects are common. Non-adherence and reduced relative dose intensity are both associated with poorer outcomes in the community setting but are rarely reported in clinical trials. The purpose of this study is to quantify adherence and relative dose intensity in oncology clinical trials and to determine patient and study related factors that influence adherence and relative dose intensity. Methods Patients were identified from non-industry-funded clinical trials conducted between 1 January 2009 and 31 March 2013 at the University of Wisconsin Carbone Cancer Center. Data were extracted from primary research records. Descriptive statistics and linear regression modeling was performed using SAS 9.4. Results A total of 17 clinical trials and 266 subjects were included. Mean adherence was greater than 97% for the first eight cycles. Mean relative dose intensity was less than 90% for the first cycle and declined over time. Male gender, a performance status of 1 or 2, metastatic disease, and traveling more than 90 miles to reach the cancer center were associated with higher relative dose intensity. Conclusions Patients with cancer enrolled in clinical trials are highly adherent but unlikely to achieve protocol specified relative dose intensity. Given that determining the phase II dose is the primary endpoint of phase I trials, incorporating relative dose intensity into this determination should be considered.

Clinical Trial Characteristics and Barriers to Participant Accrual: The MD Anderson Cancer Center Experience over 30 years, a Historical Foundation for Trial Improvement.

Purpose: Slow-accruing clinical trials delay the translation of basic biomedical research, contribute to increasing health care costs, and may prohibit trials from reaching their original goals.Experimental Design: We analyzed a prospectively maintained institutional database that tracks all clinical studies at the MD Anderson Cancer Center (Houston, TX). Inclusion criteria were activated phase I-III trials, maximum projected accrual ≥10 participants, and activation prior to March 25, 2011. The primary outcome was slow accrual, defined as <2 participants per year. Correlations of trial characteristics with slow accrual were assessed with logistic regression.Results: A total of 4,269 clinical trials met inclusion criteria. Trials were activated between January 5, 1981, and March 25, 2011, with a total of 145,214 participants enrolled. Median total enrolment was 16 [interquartile range (IQR), 5-34], with an average enrolment rate of 8.7 participants per year (IQR, 3.3-17.7). There were 755 (18%) trials classified as slow accruing. On multivariable analysis, slow accrual exhibited robust associations with national cooperative group trials (OR = 4.16, P < 0.0001 vs. industry sponsored), time from trial activation to first enrolment (OR = 1.13 per month, P < 0.0001), and maximum targeted accrual (OR = 0.16 per log10 increase, P < 0.0001). Recursive partitioning analysis identified trials requiring more than 70 days (2.3 months) between activation and first participant enrolment as having higher odds of slow accrual (23% vs. 5%, OR = 5.56, P < 0.0001).Conclusions: We identified factors associated with slow trial accrual. Given the lack of data on clinical trials at the institutional level, these data will help build a foundation from which targeted initiatives may be developed to improve the clinical trial enterprise. Clin Cancer Res; 23(6); 1414-21. ©2017 AACR.

A multicenter phase 1/2a dose-escalation study of the antioxidant moiety of vitamin E 2,2,5,7,8-pentamethyl-6-chromanol (APC-100) in men with advanced prostate cancer.

BACKGROUND: A phase 1/2a dose escalation study of APC-100 (2,2,5,7,8-Pentamethyl-6-chromanol) was conducted to determine maximum tolerated dose (MTD), recommended phase 2 dose, toxicities and efficacy in men with castrate-resistant prostate cancer (CRPC). METHODS: This open label phase 1/2a study utilizes a time-to-event reassessment method (TITE-CRM) design. Patients in cohorts of 3 were treated with escalating doses of APC-100 (900 mg-2400 mg) orally once daily continuously. Cycles were 28 days. RESULTS: Twenty patients with CRPC were enrolled in the dose escalation cohort. One possible DLT (elevated ALT) was seen at dose level 1. No other DLTs were seen and no dose reductions were required. Most frequent AEs included nausea (grade 1 in 6 patients) and elevated transaminases (grade 1-3 in 5 patients). After enrolment of 20 patients the MTD was not reached, however the maximal feasible dose was exceeded due to the number of capsules ingested. Five of the 20 patients had stable disease as their best response. The median progression free survival (PFS) for the cohort was 2.8 months (range 1-8). CONCLUSIONS: APC-100 is a novel agent with dual mechanism of action functioning both as potent antioxidant as well as antiandrogen. No detectable APC-100 was found in the plasma at dose level 5 (2100 mg) and it was felt that maximal feasibility was nearly reached. APC-100 is being reformulated as a tablet to allow further dose escalation. Once a recommended phase 2 dose is established, future studies in prostate cancer chemoprevention should be conducted.

Adjuvant sunitinib or sorafenib for high-risk, non-metastatic renal-cell carcinoma (ECOG-ACRIN E2805): a double-blind, placebo-controlled, randomised, phase 3 trial.

BACKGROUND: Renal-cell carcinoma is highly vascular, and proliferates primarily through dysregulation of the vascular endothelial growth factor (VEGF) pathway. We tested sunitinib and sorafenib, two oral anti-angiogenic agents that are effective in advanced renal-cell carcinoma, in patients with resected local disease at high risk for recurrence. METHODS: In this double-blind, placebo-controlled, randomised, phase 3 trial, we enrolled patients at 226 study centres in the USA and Canada. Eligible patients had pathological stage high-grade T1b or greater with completely resected non-metastatic renal-cell carcinoma and adequate cardiac, renal, and hepatic function. Patients were stratified by recurrence risk, histology, Eastern Cooperative Oncology Group (ECOG) performance status, and surgical approach, and computerised double-blind randomisation was done centrally with permuted blocks. Patients were randomly assigned (1:1:1) to receive 54 weeks of sunitinib 50 mg per day orally throughout the first 4 weeks of each 6 week cycle, sorafenib 400 mg twice per day orally throughout each cycle, or placebo. Placebo could be sunitinib placebo given continuously for 4 weeks of every 6 week cycle or sorafenib placebo given twice per day throughout the study. The primary objective was to compare disease-free survival between each experimental group and placebo in the intention-to-treat population. All treated patients with at least one follow-up assessment were included in the safety analysis. This trial is registered with ClinicalTrials.gov, number NCT00326898. FINDINGS: Between April 24, 2006, and Sept 1, 2010, 1943 patients from the National Clinical Trials Network were randomly assigned to sunitinib (n=647), sorafenib (n=649), or placebo (n=647). Following high rates of toxicity-related discontinuation after 1323 patients had enrolled (treatment discontinued by 193 [44%] of 438 patients on sunitinib, 199 [45%] of 441 patients on sorafenib), the starting dose of each drug was reduced and then individually titrated up to the original full doses. On Oct 16, 2014, because of low conditional power for the primary endpoint, the ECOG-ACRIN Data Safety Monitoring Committee recommended that blinded follow-up cease and the results be released. The primary analysis showed no significant differences in disease-free survival. Median disease-free survival was 5·8 years (IQR 1·6-8·2) for sunitinib (hazard ratio [HR] 1·02, 97·5% CI 0·85-1·23, p=0·8038), 6·1 years (IQR 1·7-not estimable [NE]) for sorafenib (HR 0·97, 97·5% CI 0·80-1·17, p=0·7184), and 6·6 years (IQR 1·5-NE) for placebo. The most common grade 3 or worse adverse events were hypertension (105 [17%] patients on sunitinib and 102 [16%] patients on sorafenib), hand-foot syndrome (94 [15%] patients on sunitinib and 208 [33%] patients on sorafenib), rash (15 [2%] patients on sunitinib and 95 [15%] patients on sorafenib), and fatigue 110 [18%] patients on sunitinib [corrected]. There were five deaths related to treatment or occurring within 30 days of the end of treatment; one patient receiving sorafenib died from infectious colitis while on treatment and four patients receiving sunitinib died, with one death due to each of neurological sequelae, sequelae of gastric perforation, pulmonary embolus, and disease progression. Revised dosing still resulted in high toxicity. INTERPRETATION: Adjuvant treatment with the VEGF receptor tyrosine kinase inhibitors sorafenib or sunitinib showed no survival benefit relative to placebo in a definitive phase 3 study. Furthermore, substantial treatment discontinuation occurred because of excessive toxicity, despite dose reductions. These results provide a strong rationale against the use of these drugs for high-risk kidney cancer in the adjuvant setting and suggest that the biology of cancer recurrence might be independent of angiogenesis. FUNDING: US National Cancer Institute and ECOG-ACRIN Cancer Research Group, Pfizer, and Bayer.

Trial Design and Objectives for Castration-Resistant Prostate Cancer: Updated Recommendations From the Prostate Cancer Clinical Trials Working Group 3.

PURPOSE: Evolving treatments, disease phenotypes, and biology, together with a changing drug development environment, have created the need to revise castration-resistant prostate cancer (CRPC) clinical trial recommendations to succeed those from prior Prostate Cancer Clinical Trials Working Groups. METHODS: An international expert committee of prostate cancer clinical investigators (the Prostate Cancer Clinical Trials Working Group 3 [PCWG3]) was reconvened and expanded and met in 2012-2015 to formulate updated criteria on the basis of emerging trial data and validation studies of the Prostate Cancer Clinical Trials Working Group 2 recommendations. RESULTS: PCWG3 recommends that baseline patient assessment include tumor histology, detailed records of prior systemic treatments and responses, and a detailed reporting of disease subtypes based on an anatomic pattern of metastatic spread. New recommendations for trial outcome measures include the time to event end point of symptomatic skeletal events, as well as time to first metastasis and time to progression for trials in the nonmetastatic CRPC state. PCWG3 introduces the concept of no longer clinically benefiting to underscore the distinction between first evidence of progression and the clinical need to terminate or change treatment, and the importance of documenting progression in existing lesions as distinct from the development of new lesions. Serial biologic profiling using tumor samples from biopsies, blood-based diagnostics, and/or imaging is also recommended to gain insight into mechanisms of resistance and to identify predictive biomarkers of sensitivity for use in prospective trials. CONCLUSION: PCWG3 moves drug development closer to unmet needs in clinical practice by focusing on disease manifestations most likely to affect prognosis adversely for therapeutics tested in both nonmetastatic and metastatic CRPC populations. Consultation with regulatory authorities is recommended if a trial is intended to seek support for drug approval.

Effect of Renal Impairment on the Pharmacokinetics and Safety of Axitinib.

BACKGROUND: Axitinib, an inhibitor of vascular endothelial growth factor (VEGF) receptors, is approved as second-line treatment for advanced renal cell carcinoma (RCC). Agents targeting the VEGF pathway may induce renal toxicities, which may be influenced by pre-existing renal dysfunction. OBJECTIVE: The objective was to characterize axitinib pharmacokinetics and safety in patients with renal impairment. PATIENTS AND METHODS: Effect of renal function (baseline creatinine clearance [CrCL]) on axitinib clearance was evaluated in a population pharmacokinetic model in 207 patients with advanced solid tumors who received a standard axitinib starting dose, and in 383 healthy volunteers. Axitinib safety according to baseline CrCL was assessed in previously treated patients with RCC (n = 350) who received axitinib in the phase 3 AXIS study. RESULTS: Median axitinib clearance was 14.0, 10.7, 12.3, 7.81, and 12.6 L/h, respectively, in individuals with normal renal function (≥90 ml/min; n = 381), mild renal impairment (60-89 ml/min; n = 139), moderate renal impairment (30-59 ml/min; n = 64), severe renal impairment (15-29 ml/min; n = 5), and end-stage renal disease (<15 ml/min; n = 1). The population pharmacokinetic model adequately predicted axitinib clearance in individuals with severe renal impairment or end-stage renal disease. Grade ≥3 adverse events (AEs) were reported in 63 % of patients with normal renal function or mild impairment, 77 % with moderate impairment, and 50 % with severe impairment; study discontinuations due to AEs were 10 %, 11 %, and 0 %, respectively. CONCLUSIONS: Axitinib pharmacokinetics and safety were similar regardless of baseline renal function; no starting-dose adjustment is needed for patients with pre-existing mild to severe renal impairment.

A phase I study of selumetinib (AZD6244/ARRY-142866), a MEK1/2 inhibitor, in combination with cetuximab in refractory solid tumors and KRAS mutant colorectal cancer.

BACKGROUND: KRAS mutations are clinically important predictors of resistance to EGFR-directed therapies in colorectal cancer (CRC). Oncogenic activation of the RAS/RAF/MEK/ERK signaling cascade mediates proliferation independent of growth factor signaling. We hypothesized that targeting MEK with selumetinib could overcome resistance to cetuximab in KRAS mutant CRC. METHODS: A phase I study (NCT01287130) was undertaken to determine the tolerability, and pharmacokinetic profiles of the combination of selumetinib and cetuximab, with an expanded cohort in KRAS-mutant CRC. RESULTS: 15 patients were treated in the dose escalation cohort and 18 patients were treated in the expansion cohort. Two dose-limiting toxicities were observed. One grade 3 acneiform rash and one grade 4 hypomagnesemia occurred. The most common grade 1 and 2 adverse events included rash, nausea/vomiting, diarrhea, and fatigue. The maximum tolerated dose was established at selumetinib 75 mg p.o. BID and cetuximab 250 mg/m(2) weekly following a 400 mg/m(2) load. Best clinical response in the dose escalation group included 1 unconfirmed partial response in a patient with CRC and stable disease (SD) in 5 patients (1 squamous cell carcinoma of the tonsil, 1 non-small cell lung cancer, and 3 CRC), and in the KRAS-mutant CRC dose expansion cohort, of the 14 patients who were evaluable for response, 5 patients had SD and 9 patients had progressive disease. CONCLUSIONS: The combination of selumetinib and cetuximab is safe and well tolerated. Minimal anti-tumor activity was observed in KRAS-mutant refractory metastatic CRC. Further investigations might be warranted in other cancer subtypes.

Inhibitor of p52 NF-κB subunit and androgen receptor (AR) interaction reduces growth of human prostate cancer cells by abrogating nuclear translocation of p52 and phosphorylated AR(ser81).

Accumulating evidence shows that androgen receptor (AR) activation and signaling plays a key role in growth and progression in all stages of prostate cancer, even under low androgen levels or in the absence of androgen in the castration-resistant prostate cancer. Sustained activation of AR under androgen-deprived conditions may be due to its interaction with co-activators, such as p52 NF-κB subunit, and/or an increase in its stability by phosphorylation that delays its degradation. Here we identified a specific inhibitor of AR/p52 interaction, AR/p52-02, via a high throughput screen based on the reconstitution of Gaussia Luciferase. We found that AR/p52-02 markedly inhibited growth of both castration-resistant C4-2 (IC50 ∼6 µM) and parental androgen-dependent LNCaP (IC50 ∼4 µM) human prostate cancer cells under low androgen conditions. Growth inhibition was associated with significantly reduced nuclear p52 levels and DNA binding activity, as well as decreased phosphorylation of AR at serine 81, increased AR ubiquitination, and decreased AR transcriptional activity as indicated by decreased prostate-specific antigen (PSA) mRNA levels in both cell lines. AR/p52-02 also caused a reduction in levels of p21(WAF/CIP1), which is a direct AR targeted gene in that its expression correlates with androgen stimulation and mitogenic proliferation in prostate cancer under physiologic levels of androgen, likely by disrupting the AR signaling axis. The reduced level of cyclinD1 reported previously for this compound may be due to the reduction in nuclear presence and activity of p52, which directly regulates cyclinD1 expression, as well as the reduction in p21(WAF/CIP1), since p21(WAF/CIP1) is reported to stabilize nuclear cyclinD1 in prostate cancer. Overall, the data suggest that specifically inhibiting the interaction of AR with p52 and blocking activity of p52 and pARser81 may be an effective means of reducing castration-resistant prostate cancer cell growth.

Atrasentan in Patients With Advanced Renal Cell Carcinoma: A Phase 2 Trial of the ECOG-ACRIN Cancer Research Group (E6800).

BACKGROUND: Atrasentan, an oral endothelin receptor A antagonist, demonstrated phase 1 activity in patients with renal cell carcinoma (RCC). A phase 2 study was undertaken in patients with measurable or bone-only metastatic RCC in the pre-VEGF/TKI era. METHODS AND MATERIALS: Patients were stratified by disease status and prior immunotherapy. Eligible patients had no prior chemotherapy, 0 to 1 prior immunotherapies, and an Eastern Cooperative Oncology Group performance status of 0 to 2. Patients received atrasentan 10 mg per day until progression. The primary end point was progression-free (PF) rate at 6 months. Rates of 25% among patients treated with prior immunotherapy and 45% among patients with no prior immunotherapy were considered promising. A 2-stage design was used for cohorts without prior immunotherapy. RESULTS: From 2003 to 2005, 98 patients were registered. Median treatment duration was 9.9 weeks (range, 0.3-107 weeks). Toxicities were mild; 71% of patients reported no grade 3 or higher treatment-related events. Grade 4 events included neutropenia (n = 3), dyspnea (n = 2), thrombosis (n = 1), and arrhythmia (n = 1). Two grade 5 events (dyspnea and constitutional) were possibly treatment related. Six-month PF rates (90% confidence interval) were 14% (6-25), 0% (0-39), 8% (1-23), and 22% (8-44), respectively, for patients with prior immunotherapy/measurable disease (n = 44), prior immunotherapy/bone metastases (n = 6), no prior immunotherapy/measurable disease (n = 25), and no prior immunotherapy/bone metastases (n = 18). Median PF survival was 2.3 months (95% confidence interval, 2.0-3.5 months). CONCLUSION: Although well tolerated, atrasentan did not yield 6-month PF rates supporting its use as first-line monotherapy in patients with advanced RCC.

Leinamycin E1 acting as an anticancer prodrug activated by reactive oxygen species.

Leinamycin (LNM) is a potent antitumor antibiotic produced by Streptomyces atroolivaceus S-140, featuring an unusual 1,3-dioxo-1,2-dithiolane moiety that is spiro-fused to a thiazole-containing 18-membered lactam ring. Upon reductive activation in the presence of cellular thiols, LNM exerts its antitumor activity by an episulfonium ion-mediated DNA alkylation. Previously, we have cloned the lnm gene cluster from S. atroolivaceus S-140 and characterized the biosynthetic machinery responsible for the 18-membered lactam backbone and the alkyl branch at C3 of LNM. We now report the isolation and characterization of leinamycin E1 (LNM E1) from S. atroolivacues SB3033, a ΔlnmE mutant strain of S. atroolivaceus S-140. Complementary to the reductive activation of LNM by cellular thiols, LNM E1 can be oxidatively activated by cellular reactive oxygen species (ROS) to generate a similar episulfonium ion intermediate, thereby alkylating DNA and leading to eventual cell death. The feasibility of exploiting LNM E1 as an anticancer prodrug activated by ROS was demonstrated in two prostate cancer cell lines, LNCaP and DU-145. Because many cancer cells are under higher cellular oxidative stress with increased levels of ROS than normal cells, these findings support the idea of exploiting ROS as a means to target cancer cells and highlight LNM E1 as a novel lead for the development of anticancer prodrugs activated by ROS. The structure of LNM E1 also reveals critical new insights into LNM biosynthesis, setting the stage to investigate sulfur incorporation, as well as the tailoring steps that convert the nascent hybrid peptide-polyketide biosynthetic intermediate into LNM.

Potential cytochrome P-450 drug-drug interactions in adults with metastatic solid tumors and effect on eligibility for Phase I clinical trials.

PURPOSE: Potential cytochrome P-450 (CYP) drug-drug interactions in adults with metastatic solid tumors and their effect on eligibility for Phase I clinical trials were characterized. METHODS: This study included adult patients with metastatic solid tumors seen by a medical oncologist from January 2008 through July 2011. The medications used by these patients were identified. Each medication's potential for interacting with CYP isozymes was also characterized. Medication changes required to meet Phase I trial eligibility criteria were also reviewed. RESULTS: Data from 1773 patients were analyzed: 1489 were not enrolled in a Phase I trial and 284 were enrolled in a Phase I trial. Polypharmacy was significantly more prevalent in the group enrolled in a Phase I trial compared with those not enrolled (95% versus 80%, p < 0.001). The majority of patients not enrolled in a Phase I trial were taking at least one CYP isozyme inhibitor (87%) and at least one CYP isozyme inducer (45%). In a separate analysis, four Phase I trials were evaluated. Of 295 screened patients, 3.2% could not enroll due to concurrent medications. Charts from 74 enrolled patients revealed 655 concurrent medications­93 medications required further review for eligibility involving 51 (69%) of patients. Of the 93 medications, 38 (41%) were stopped and 41 (44%) were changed for the study. CONCLUSION: Polypharmacy and the use of medications that interact with CYP isoyzmes were common in adult patients with metastatic solid tumors. Patients enrolling in Phase I studies often require medication changes to meet eligibility requirements.

Effects of Adjuvant Sorafenib and Sunitinib on Cardiac Function in Renal Cell Carcinoma Patients without Overt Metastases: Results from ASSURE, ECOG 2805.

PURPOSE: Sunitinib and sorafenib are used widely in the treatment of renal cell carcinoma (RCC). These agents are associated with a significant incidence of cardiovascular (CV) dysfunction and left ventricular ejection fraction (LVEF) declines, observed largely in the metastatic setting. However, in the adjuvant population, the CV effects of these agents remain unknown. We prospectively defined the incidence of cardiotoxicity among resected, high-risk RCC patients treated with these agents. EXPERIMENTAL DESIGN: Sunitinib, sorafenib, or placebo was administered for up to 12 months in patients with high-risk, resected RCC. LVEF was measured by multigated acquisition (MUGA) scans at standard intervals. Additional CV adverse events were reported according to NCI Common Terminology Criteria for Adverse Events (CTCAE). RESULTS: Among 1,943 patients randomized, 1,599 had at least 1 post-baseline MUGA. Within 6 months, 21 patients (1.3%) experienced a cardiac event, defined as an LVEF decline from baseline that was >15% and below the institutional lower limit of normal. Nine of 513 patients (1.8%) were on sunitinib, 7 of 508 (1.4%) on sorafenib, and 5 of 578 (0.9%) on placebo (P = 0.28 and 0.56 comparing sunitinib and sorafenib to placebo, respectively). With dose interruption or adjustment, 16 of the 21 recovered their LVEF to >50%. The incidence of symptomatic heart failure, arrhythmia, or myocardial ischemia did not differ among groups. CONCLUSIONS: In the adjuvant setting, we prospectively define low incidence of cardiotoxicity with sunitinib and sorafenib. These findings may be related to close CV monitoring, or potentially to fewer CV comorbidities in our nonmetastatic population.

Expression of spermidine/spermine N(1) -acetyl transferase (SSAT) in human prostate tissues is related to prostate cancer progression and metastasis.

INTRODUCTION: Prostate cancer (PCa) in many patients remains indolent for the rest of their lives, but in some patients, it progresses to lethal metastatic disease. Gleason score is the current clinical method for PCa prognosis. It cannot reliably identify aggressive PCa, when GS is ≤ 7. It is shown that oxidative stress plays a key role in PCa progression. We have shown that in cultured human PCa cells, an activation of spermidine/spermine N(1) -acetyl transferase (SSAT; EC 2.3.1.57) enzyme initiates a polyamine oxidation pathway and generates copious amounts of reactive oxygen species in polyamine-rich PCa cells. METHOD: We used RNA in situ hybridization and immunohistochemistry methods to detect SSAT mRNA and protein expression in two tissue microarrays (TMA) created from patient's prostate tissues. We analyzed 423 patient's prostate tissues in the two TMAs. RESULTS: Our data show that there is a significant increase in both SSAT mRNA and the enzyme protein in the PCa cells as compared to their benign counterpart. This increase is even more pronounced in metastatic PCa tissues as compared to the PCa localized in the prostate. In the prostatectomy tissues from early-stage patients, the SSAT protein level is also high in the tissues obtained from the patients who ultimately progress to advanced metastatic disease. DISCUSSION: Based on these results combined with published data from our and other laboratories, we propose an activation of an autocrine feed-forward loop of PCa cell proliferation in the absence of androgen as a possible mechanism of castrate-resistant prostate cancer growth.