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.

Abstract 5408: AI powered-platform to predict gene modifications from prostate and breast cancer whole slide images

There is little published evidence of predicting cancer genotypes directly from tissue histology, especially for breast and prostate cancers. Artificial intelligence (AI) enables discriminating and extracting morphological features reflective of the underlying genomic alterations at visual and subvisual levels. We have built a morphology-based and AI-powered platform for cancer genotyping, risk stratification and outcome prediction that addresses the needs for treatment decision-making in a cost effective and timely fashion. A cohort of 390 prostate and 742 invasive breast cancer patients with known molecular status of key genes, such as TP53, PIK3CA, MYC, ERBB2, TMPRSS2-ERG and PTEN from The Cancer Genome Atlas were included in this study. Hematoxylin and eosin (H&E) stained whole slide images (WSI) of the cancer tissue sections were available at 20x or 40x. The WSI from the two cancer cohorts were split 2:1 into a training and test dataset, respectively. Our platform involved two different deep Convolutional Neural Network (DCNN) architectures. The platform first divided each WSI into multiple tiles. Each tile was then analyzed using a DCNN that graded the tile and generated a high dimensional vector to provide a mathematical representation of the morphology. The combination of high dimensional vectors across the WSI was then fed into a second DCNN that generated a morphological score, which predicted whether the gene under consideration was wild type or modified. Our platform has achieved 70 - 80% accuracy as defined by the Area under the Curve for the receiver operating characteristics curves for the genetic markers on the test cohorts (Table 1). Our platform can predict genotypes/molecular alterations directly from H&E stained WSI with high accuracy. This technology presents a novel, practical and cost-effective approach for cancer molecular classification and risk stratification, enabling timely and optimal treatment decision-making for positive clinical outcomes.

Genotype Prediction for Breast Cancer (BrCa) and Prostate Cancer (PCa) from WSI Cohort Molecular Biomarker Training Dataset (n) Test Dataset (n) Test ROC AUC Score (%) Gene Modification/Loss Intact/Wild type Gene Modification/Loss Intact/Wild type BrCa TP53 196 302 96 149 80 PIK3CA 153 344 75 170 74 MYC 68 414 33 204 77 ERBB2 66 416 32 205 78 PCa TMPRSS2-ERG 104 157 51 78 70 PTEN 57 201 28 99 73

Citation Format: Wei Huang, Parag Jain, Chensu Xie, Hassan Muhammad, Hirak Basu, George Wilding, Rajat Roy. AI powered-platform to predict gene modifications from prostate and breast cancer whole slide images. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5408.

Abstract P6-01-18: Predicting response of triple negative breast cancer to neoadjuvant chemotherapy using a deep convolutional neural network-based artificial intelligence tool

Background: Triple-negative breast cancer (TNBC) is commonly treated with neoadjuvant chemotherapy (NAC). Pathologic complete response (pCR) to NAC is associated with improved patient outcomes. The ability to predict which patients have high likelihood to achieve pCR has important clinical implications. We developed and validated a deep convolutional neural network (CNN)–based artificial intelligence (AI) model to extract morphometric features of TNBC to predict response to NAC. Methods: Whole-slide images (WSIs) of hematoxylin and eosin–stained core biopsies of 165 (pathologic complete response [pCR] in 60 and non-pCR in 105) and 78 (pCR in 31 and non-pCR in 47) TNBC patients, respectively, were used for training and validation of the model. The model extracted morphometric features from WSIs in an unsupervised way and transformed the image tiles from WSIs into high-dimensional vectors, generating clusters of morphologically similar patterns. Downstream ranking of clusters using neural networks provided regions of interest with high or low predictive value for NAC response. Morphometric scores combined with clinical TNM stage gave AI prediction scores; a low score close to 0 and high score close to 1, respectively, represented a high or low probability of pCR, respectively. Results: The predictive ability of the AI score for the entire cohort of 78 TNBC patients ascertained by receiver operating characteristic (ROC) analysis demonstrated area under the curve (AUC) of 75.5%. The AUC for stage I, II, and III disease was 88.1%, 73.7%, and 74.7% respectively. The performance of the AI scores was also analyzed based on their distribution into quartiles. Patients in the highest score quartile were predicted to not have pCR and those in the lowest score quartile were predicted to have pCR. Of the 20 patients in the lowest score quartile, 15 experienced pCR yielding a positive predictive value of the AI score for pCR of 75%. Of the 20 patients in the highest score quartile, 16 did not have pCR, yielding a negative predictive value of 80%. Conclusions: This is the first demonstration of using an AI tool to predict response to NAC in patients with TNBC. These results if validated in subsequent studies, could inform individualized decisions regarding intensity of NAC, including options to de-escalate NAC in patients with TNBC who are likely to achieve pCR.

Citation Format: Savitri Krishnamurthy, Parag Jain, Debu Tripathy, Hassan Muhammad, Wei huang, Hua Yang, Shivaani Kummar, George Wilding, Rajat Roy, Ramandeep Randhawa. Predicting response of triple negative breast cancer to neoadjuvant chemotherapy using a deep convolutional neural network-based artificial intelligence tool [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-18.

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.

Abstract 2357: Inhibition of CDK8/19 mediator kinase suppresses primary and metastatic growth of castration-resistant prostate cancer

Following androgen deprivation therapy (ADT), prostate cancers (PCa) progress to castration resistant prostate cancer (CRPC) status, independent of androgen signaling, through changes in androgen receptor (AR) or by converting to AR-negative forms. Metastatic CRPC remains incurable, and the most potent new drugs prolong survival by only a few months. There is an urgent need for novel agents against advanced CRPC. CDK8 and CDK19 are two isoforms of Mediator kinase, which regulates transcriptional reprogramming, a key process in cancer development, metastasis, and drug resistance. Bioinformatic analysis of clinical prostate cancers shows that CDK19 expression increases during PCa development and progression reaching higher levels than in any other cancers, whereas CDK8 expression increases when PCa becomes CRPC. We have investigated the effects of CDK8/19 Mediator kinase inhibition on gene expression and tumor growth in several CPRC tumor models, growing subcutaneously or in the bone, the principal cause of PCa lethality. CDK8/19 inhibition decreased androgen-stimulated expression of the most strongly androgen-regulated genes, including PSA, in androgen-responsive PCa in vitro and in vivo. CRISPR knockout of both CDK8 and CDK19 in 22Rv1 CRPC cells that express both full-length AR and its androgen-independent V7 variant, had little effect on the tumor growth in intact male mice but strongly suppressed tumor growth in castrated animals. Moreover, re-expression of CDK19 but not of its kinase-dead mutant partially restored tumor growth in castrated mice. Similarly, SNX631, a selective CDK8/19 inhibitor, had little effect on 22Rv1 growth in intact mice but strongly suppressed the growth of these cells (but not of their knockout derivative) in castrated mice. Prolonged (up to 300 days) treatment with SNX631 induced tumor shrinkage and disappearance in a subset of 22Rv1 tumors grown in castrated animals. Transcriptomic analysis revealed that CDK8/19 inhibition or knockout suppressed castration-induced transcriptional reprogramming in tumor cells and affected stromal gene expression. SNX631 also inhibited the growth of a CRPC PDX derived from a PCa patient who failed casodex, abiraterone, and docetaxel, in castrated mice. SNX631 also significantly inhibited in vivo growth of AR-negative PC3 cells both in the flank and in the bone, the principal metastatic site of PCa. These results warrant the development of CDK8/19 inhibitors for the presently incurable metastatic CRPC. Funding acknowledgement: This research was funded by NIH grant R44CA203184 (M.C., I.R., M.L., Y.S.)

Citation Format: Jing Li, Thomas Hilimire, Chen Cheng, Eugenia V. Broude, Yueying Liu, Michael B. Lilly, Yusuke Shiozawa, George Wilding, Igor B. Roninson, Mengqian Chen. Inhibition of CDK8/19 mediator kinase suppresses primary and metastatic growth of castration-resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2357.

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.

Timing of the definitive procedure and ileostomy closure for total colonic aganglionosis HD: Systematic review

AIM

To establish the cogency of recommendations for the appropriate age for pull-through and ileostomy closure in Total Colonic Aganglionosis-Hirschsprung Disease's (TCA-HD).

METHOD

Medline, PubMed, Cochrane, and the ClinicalKey databases were searched without date restriction. The studies that reported TCA-HD cases were evaluated for the number of cases, age at the definitive procedure, age at the ileostomy closure, reported complications, and the type of procedure. Perianal excoriation and diaper rash rates were analyzed using SPSS software, with p < 0.05 considered significant.

RESULTS

Twenty-five studies mentioned TCA-HD findings between 1968 and 2019. The total number of patients who had definitive surgery was 218. Analysis showed no correlation between development of diaper rash and the age of the patient at the time of the definitive surgery or ileostomy closure. Studies scored between six and nine of nine possible stars on the NOS scoring system.

CONCLUSION

There is no correlation between age of surgery and postoperative diaper rash. Delaying the definitive procedure or ileostomy closure for TCA-HD has limited support on a review of current studies. The perianal excoriation/diaper rash is not reported in the literature at a high enough frequency to warrant keeping a diverting ileostomy until toilet trained of urine.

TYPE OF STUDY

Systematic review and meta-analysis. Levels of evidence IV.

Abstract 4791: Metabolic switch from glycolysis to oxidative phosphorylation (ox-phos) provides survival advantage to anti-androgen-treated prostate cancer cells and make them vulnerable to mitochondrial metabolism inhibitors IACS-010759 and CB-839

Background: Most cancer cells depend more on glycolysis for their energy need compared with their normal counterparts incubated under identical condition. In addition to glycolysis, tumor cells also engage mitochondrial ox-phos to support growth. Here, we show that PCa cells surviving under anti-androgen enzalutamide (ENZA) treatment switch from glycolysis to ox-phos for their energy need and are more vulnerable to mitochondria-targeted metabolic inhibitors. We have also standardized a high-resolution quantitative fluorescence microscopic method to detect this metabolic switch in patient circulating tumor cells (CTCs).

Methods: Seahorse assay has been used to compare mitochondrial metabolism in ENZA treated anti-androgen-sensitive LNCaP and -resistant C4-2 and PCa2b cells. The Seahorse data were supported by mass spectroscopic analysis of corresponding metabolites and metabolic fluxes. An ex vivo fluorescence staining for the CTC mitochondria with high ox-phos followed by high-resolution quantitative microscopic image analysis method has been standardized to follow such changes in cultured cells and patient CTCs.

Results: Seahorse, mass spectroscopy and high-resolution microscopy of mitochondrial ox-phos showed that ENZA significantly decreases glycolysis and increases ox-phos in all surviving PCa cells within 24h of treatment. These cells are more vulnerable to treatment with mitochondrial ox-phos inhibitor IACS-010759 and a glutaminase inhibitor CB-839. High-resolution microscopic analysis of CTCs has thus far been performed in 18 patient blood samples. Six out of the 18 patients developed resistance to anti-androgen therapy within 0-6 months of sample collection. CTCs from all six patients showed a relatively higher average fluorescence due to high mitochondrial ox-phos as compared with the rest of the patients.

Discussion: The data presented here may lead to informed combination therapy for selected PCa patients developing resistance to anti-androgen therapy for better clinical outcome.

Citation Format: Hirak S. Basu, Nathaniel Wilganowski, Samantha Robertson, Sumankalai Ramachandran, Amado Zurita-Saavedra, Mark Titus, Evan Cohen, James Reuben, George Wilding. Metabolic switch from glycolysis to oxidative phosphorylation (ox-phos) provides survival advantage to anti-androgen-treated prostate cancer cells and make them vulnerable to mitochondrial metabolism inhibitors IACS-010759 and CB-839 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4791.

Abstract B091: Small-molecule inhibitors targeting a specific metabolic pathway for precision therapy of advanced castrate-resistant prostate cancer

Introduction: The mechanism of prostate cancer (PCa) progression to the mostly lethal, metastatic, castrate-resistant stage (mCRPC) remains generally unknown. This prevents identifying patients likely to progress to mCRPC and designing new therapies for their treatment. A transcription factor JunD is overexpressed in PCa, but not in normal prostate epithelial cells. It complexes with androgen receptor (AR) to induce spermidine/spermine acetyl transferase (SSAT) [3]. SSAT initiates polyamine oxidation that generates copious amounts of reactive oxygen species (ROS) production in polyamine-rich PCa cells. ROS activate NF-κB. NF-κB can also induce SSAT and activate AR. This sets up a feed-forward loop for PCa growth at low androgen.

Here, we present one mechanism of PCa progression to CRPC as well as its invasion and metastasis that may provide predictive biomarkers to identify patients with potentially lethal PCa at an early stage. Effects of an agent that can block both AR-JunD and AR-NF-κB interactions and prevent growth of PCa cells in vitro as well as in vivo xenografts will also be presented.

Method: We have used a novel microscale device to separate invading from noninvading PCa cells ex vivo in a bone microenvironment. Immunocytochemistry (ICC), proteomic and metabolomic techniques have been employed to analyze the separated cells to understand the mechanism of invasion. Gaussia luciferase reconstitution assay has been used in a high-throughput screen (HTS) to identify inhibitors of AR-JunD and AR-NF-κB interactions. State-of-the-art in vitro cell growth assay along with in vivo pharmacokinetic (PK), maximum tolerated dose (MTD) and enzalutamide-resistant CRPC cell xenograft growth in nude mice are used to optimize the lead.

Summary of Unpublished Results: Immunocytochemistry (ICC) data show that in cultured enzalutamide-resistant C4-2 and -sensitive LNCaP cells as well as in some patient PCa cells, more SSAT-positive cells are in the migratory than in the stationary section of the microscale device. Metabolomic analysis show a decrease in 3-phospho-glycerate levels in C4-2 cells, suggesting a decrease in GAPDH enzymatic activity that is related to an enhanced oxidation of GAPDH protein.

Our published data of screening of 27,000+ compounds from two different chemical libraries detected a single compound that specifically inhibits both AR-JunD and AR-NF-κB2 (p52) interactions. We have synthesized several of its analogs. Lead analogs inhibit growth of AR-positive C4-2 and LNCaP cells, but have little effect on the growth of AR-negative PC-3 and SSAT-silent LNCaP siSSAT cells in culture. Co-immunoprecipitation (co-IP) assay shows its efficacy in inhibiting AR-JunD and AR-p52 interactions in LNCaP cells. It has been formulated in 25% ethanol:water and administered to nude mice orally. It is well tolerated at 50 mg/kg p.o. daily for more than 28 days and has a serum Cmax of ~ 3 μM within 30 minutes and a plasma t1/2 of ~1 h after a single oral dose of 100 mg/kg. Twenty-four hours after dosing it is found in the flank tumor (1.5 ng/mg tissue; ~450 nM) and in the prostate tissues (10 ng/mg tissue; ~3 μM) in addition to liver and kidney. Its effects on the growth of C4-2 xenografts in nude mice will be presented.

Conclusion: A mechanism of PCa progression to CRPC and then to mCRPC provides a rational basis for targeted drug design that prevents PCa progression and metastasis. This should open up a new avenue of precision therapy of potentially lethal PCa at an early stage.

Citation Format: Hirak Basu, Nathaniel Wilganowski, Jessica Lieblich, Grace Wu, Izabela Fokt, Sumankalai Ramachandran, Jiaquin Yu, Mark Titus, Waldemar Priebe, David J. Beebe, George Wilding. Small-molecule inhibitors targeting a specific metabolic pathway for precision therapy of advanced castrate-resistant prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B091.

Abstract 3846: A metabolic pathway targeted inhibitor for precision therapy of castrate-resistant prostate cancer

Background: We have previously reported that an AP-1 factor JunD is overexpressed in PCa. It complexes with androgen receptor (AR) to induce spermidine/spermine acetyl transferase (SSAT). SSAT initiates polyamine oxidation that generates copious amounts of reactive oxygen species (ROS) production in polyamine-rich PCa cells. ROS activate NF-κB. NF-κB also induces SSAT and activates AR. This sets-up a feed-forward loop for PCa growth at low androgen. An IHC assay for SSAT can be utilized to identify PCa patients with this loop activated. AR-N-terminal targeted inhibitors that block AR interactions with JunD and NF-κB can be developed as a precision therapy for these patients. Method: We applied Immunocytochemistry (ICC), proteomic and metabolomic techniques to analyze stationary and invading cells that are separated in a novel micro-scale dvice to understand the mechanism of invasion. Gaussia luciferase reconstitution assay in a high throughput screen (HTS) to identify inhibitors of AR-JunD and AR-NF-κB interactions. In vitro cell growth assay along with in vivo pharmacokinetic (PK), maximum tolerated dose (MTD) and enzalutamide-resistant CRPC cell xenograft growth in nude mice are used to optimize the lead. Unpublished data: Immunocytochemistry (ICC) data show that in cultured enzalutamide-resistant C4-2 and -sensitive LNCaP cells as well as in some patient PCa cells, more SSAT positive cells are in the migratory than in the stationary section of the microscale device. Screening of 27,000+ compounds from 2 different chemical libraries detected a single compound that specifically inhibits both AR-JunD and AR-NF-κB2 (p52) interactions. We have synthesized several of its analogs. Lead analogs inhibit growth of AR-positive C4-2 and LNCaP cells at nanomolar concentration, but have little effect on the growth of AR-negative PC-3 and SSAT silent siSSAT cells in culture. Co-immunoprecipitation (co-IP) assay shows its efficacy in inhibiting AR-JunD and AR-p52 interactions in situ. It has been formulated in 25% ethanol:water and administered orally. PCa tumor bearing nude mice tolerated it at 50 mg/kg p.o. daily for more than 28 days and has a serum Cmax of ~ 3 μM within 30 minutes and a plasma t1/2 of ~1 h after a single oral dose of 100 mg/kg. Twenty four hours after dosing it is found in the flank tumor (1.5 ng/mg tissue; ~450 nM) and in the prostate tissues (10 ng/mg tissue; ~3 μM) in addition to liver and kidney and inhibited growth of C4-2 xenografts in nude mice.

Citation Format: Hirak S. Basu, Nathaniel L. Wilgonowski, Jessica L. Lieblich, Grace T. Wu, Izabela Fokt, Sumankalai Ramachandran, Jiaquin Yu, Mark Titus, Waldemar Priebe, David J. Beebe, George Wilding. A metabolic pathway targeted inhibitor for precision therapy of castrate-resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3846.

Small bowel fed response as measured by wireless motility capsule: Comparative analysis in healthy, gastroparetic, and constipated subjects

BACKGROUND

Small bowel fed response is an increased contractile activity pattern following the ingestion of a meal. Postprandial motility is traditionally evaluated using small bowel manometry. Wireless motility capsule (WMC) is an ingestible wireless capsule that measures pH, temperature, and intraluminal pressure. The primary aim of the study was to assess small bowel fed response captured with the non-invasive WMC. The secondary aim was to compare the fed response patterns between healthy subjects and patients with motility disorders of gastroparesis and constipation.

METHODS

All subjects had 250 cc Ensure^® meal 6 hours after WMC ingestion. Frequency of contractions (Ct), area under the curve (AUC), and motility index (MI) were analyzed during 30 minutes of pre-prandial baseline and 60 minutes postprandially in 20-minute windows.

KEY RESULTS

One hundred and eighty-eight subjects (107 healthy, 23 gastroparetics, 58 constipated) were analyzed. Healthy: Ct, AUC, and MI all increased significantly immediately after meal ingestion (P < .01). Motility parameters peak at 20-40 minutes postmeal. The motor activity decreased at the end of postprandial hour, but was still significantly higher than the fasting baseline (P < .01). Gastroparetics: All motility parameters failed to increase significantly compared to the baseline throughout the entire postprandial hour. Constipated: The fed response was similar to healthy subjects.

CONCLUSIONS AND INFERENCES

The small bowel fed response was readily observed in healthy and chronic constipation subjects with WMC but is blunted in gastroparetics. A blunted small bowel fed response suggests neuropathic changes outside the stomach and may contribute to postprandial symptoms.

Mipsagargin, a novel thapsigargin-based PSMA-activated prodrug: results of a first-in-man phase I clinical trial in patients with refractory, advanced or metastatic solid tumours

Background:

Mipsagargin (G-202; (8-O-(12-aminododecanoyl)-8-O-debutanoyl thapsigargin)-Asp-γ-Glu-γ-Glu-γ-GluGluOH)) is a novel thapsigargin-based targeted prodrug that is activated by PSMA-mediated cleavage of an inert masking peptide. The active moiety is an inhibitor of the sarcoplasmic/endoplasmic reticulum calcium adenosine triphosphatase (SERCA) pump protein that is necessary for cellular viability. We evaluated the safety of mipsagargin in patients with advanced solid tumours and established a recommended phase II dosing (RP2D) regimen.

Methods:

Patients with advanced solid tumours received mipsagargin by intravenous infusion on days 1, 2 and 3 of 28-day cycles and were allowed to continue participation in the absence of disease progression or unacceptable toxicity. The dosing began at 1.2 mg m⁻² and was escalated using a modified Fibonacci schema to determine maximally tolerated dose (MTD) with an expansion cohort at the RP2D. Plasma was analysed for mipsagargin pharmacokinetics and response was assessed using RECIST criteria.

Results:

A total of 44 patients were treated at doses ranging from 1.2 to 88 mg m⁻², including 28 patients in the dose escalation phase and 16 patients in an expansion cohort. One dose-limiting toxicity (DLT; Grade 3 rash) was observed in the dose escalation portion of the study. At 88 mg m⁻², observations of Grade 2 infusion-related reaction (IRR, 2 patients) and Grade 2 creatinine elevation (1 patient) led to declaration of 66.8 mg m⁻² as the recommended phase II dose (RP2D). Across the study, the most common treatment-related adverse events (AEs) were fatigue, rash, nausea, pyrexia and IRR. Two patients developed treatment-related Grade 3 acute renal failure that was reversible during the treatment-free portion of the cycle. To help ameliorate the IRR and creatinine elevations, a RP2D of 40 mg m⁻² on day 1 and 66.8 mg m⁻² on days 2 and 3 with prophylactic premedications and hydration on each day of infusion was established. Clinical response was not observed, but prolonged disease stabilisation was observed in a subset of patients.

Conclusions:

Mipsagargin demonstrated an acceptable tolerability and favourable pharmacokinetic profile in patients with solid tumours.

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.

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.

Phase I study of docetaxel and topotecan in patients with advanced malignancies

Background. Docetaxel and topotecan are drugs with different mechanisms of action and significant activity against various tumour types. Topotecan may influence docetaxel metabolism by inhibiting the CYP3A4 enzyme. We designed a phase I study to evaluate the maximum tolerated dose of this combination and to assess the impact of pharmaco-kinetic interactions of the two drugs on toxicity.

Methods. Docetaxel and topotecan were administered intravenously on day 1, and days 1- 5 respectively, using a phase I dose escalation design. Plasma samples were analysed to determine docetaxel and topotecan concentration by HPLC with subsequent pharmacokinetic analysis using NONMEM.

Results. Of the 17 patients enrolled in the trial, 11 had grade 3 and 4 neutropenia and 1 had grade 4 thrombocytopenia. Nonhaematological toxicities were less frequent. The maximum tolerated dose for docetaxel and topotecan were 60 mg/m2 on day 1 and 0.75 mg/m2 days 1- 5, respectively. One patient had stable disease. Subjects with grade]3 haematologic toxicity had higher plasma docetaxel or topotecan area under the curve (AUC) (docetaxel 1.0390.11 mg-hr/L versus 0.7390.13 mghr/L; topotecan 65.8914.6 mcg-hr/L versus 41.6913.9 mcg-hr/L). There was no additive effectoftheAUCofthetwodrugsonthe likelihood of grade]3 haematologic toxicity by multiple logistic regression.

Conclusion. The dose-limiting toxicity seen with the combination of docetaxel and topotecan was myelosuppression. Future trials will require growth factor support if this combination is pursued.

Abstract 4968: “Moonlighting Functions” of glycolytic enzymes relate to human prostate cancer invasion

Background: Castrate-resistant prostate cancer (CRPC) is the second leading cause of cancer deaths among US men. Currently, a large number of small and low grade prostate cancers (PCa) are being diagnosed. Only a few of them will metastasize and become lethal. A clinical method to distinguish aggressive from the indolent tumors is warranted. An enhanced glucose metabolism (Warbürg effect) and invasion of cells from their organs of origin and metastasis to distant organs are two characteristics that are ubiquitous in most solid tumors. In the last few years, the non-glycolytic activities (“moonlighting functions”) of glycolytic enzymes have been investigated in relation to cancer cell invasion. We propose that oxidatively stressed PCa cells, as a countermeasure, redirect some of the glycolytic enzymes to their moonlighting functions.

Methods: We used a novel microfluidic device that separates the invading from the non-invading PCa cells based on their migratory characteristics in a 3D collagen matrix. We performed ICC analysis of the separated cells for oxidative stress generating enzyme spermidine/spermine N1 acetyl transferase (SSAT) and glycolytic enzymes aldolase, GAPDH and F-actin levels. We also carried out proteomic analysis of aldolase and GAPDH levels and oxidation state and metabolomic analysis for enzymatic activities of those two enzymes.

Results: Under identical condition, LNCaP cells show minimum invasion, whereas between 30-40% of C4-2 cells invade more than 0.8 mm in 16 hours. ICC assay of C4-2 cells shows that most migratory C4-2 cells have SSAT overexpression, but less than 5% stationary cells show this effect. Proteomic analysis shows that androgen treatment that increases overall oxidative stress in both LNCaP and C4-2 cells actually decreases oxidation status of GAPDH in LNCaP cells and increases that in C4-2 cells. Anti-androgen enzalutamide reverses the androgen effect in both cell lines. The glycolytic activity of GAPDH decreases with an increase in protein oxidation. Our metabolomic data further confirmed an increase in GAPDH activity in LNCaP and a decrease in C4-2 cells after androgen treatment and the reversal with enzalutamide as expected from its oxidation status.

Discussion: SSAT expression and a consequent increase in oxidative stress are related to invasion of CRPC. Oxidation of certain glycolytic enzymes in CRPC cells may divert them to their moonlighting function related to cellular invasion and metastasis. These functions may be monitored in patient biopsies and/or prostatectomy tissues for PCa prognosis. Application of the microfluidic method for the separation of invading from the non-invading cells and proteogenomic and metabolomic analysis of these cells isolated from patient prostatectomy tissues are currently being standardized.

Citation Format: Jiaquan Yu, Ashley M. Weichmann, Alexandria Craig, Wei Huang, Dawn R. Church, Farideh Mehraein, Laurie L. Parker, David J. Beebe, George Wilding, Hirak S. Basu. “Moonlighting Functions” of glycolytic enzymes relate to human prostate cancer invasion. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4968.

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.

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.

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.

Abstract 2899: Mitophagy imparts enzalutamide resistance in prostate cancer

Purpose: Anti-androgens are widely used in androgen deprivation therapy (ADT), a standard-of-care for patients with recurrent prostate cancer (PCa). Unfortunately, most patients ultimately develop resistance to ADT and progress to castrate-resistant prostate cancer (CRPC). Recently, two agents that block androgen receptor activation [abiraterone acetate (Zytiga, J&J) and enzalutamide (Xtandi, Medivation/Astellas)] have been approved for CRPC therapy. While some patients respond to these therapies, many fail. We investigated if sequestration of metabolically aberrant mitochondria in the autophagosomes (mitophagy) imparts anti-androgen resistance.

Method: We studied the effects of anti-androgen enzalutamide on the autophagy of androgen-dependent LNCaP and -independent C4-2 cells. Autophagy was monitored by cellular fluorescence in cells treated with monodansylcadavarine (MDC). Cellular fluorescence due to Mitosox dye oxidation was used to identify mitochondria producing high superoxide (O2-). Mitophagy of O2- producing mitochondria was monitored using fluorescence resonance energy transfer (FRET) between MDC and Mitosox in a 96-well plate based high throughput (HTS) assay and by visualization of FRET images and quantitation of FRET image intensities using a Nikon A1 fluorescence confocal microscope and associated software.

Results: Our data show that in low androgen media, the degree of autophagy is less in C4-2 cells than in LNCaP cells. Enzalutamide treatment induces autophagy in both cell lines, but the increase in autophagy is more pronounced in the androgen-independent C4-2 than in the -dependent LNCaP cells. FRET data from both HTS and fluorescence microscopy show that while enzalutamide increases mitophagy of O2- producing mitochondria in C4-2 cells in a dose dependent manner, it decreases after an initial increase in LNCaP cells. Mitophagy of such mitochondria has also been observed by FRET based fluorescence microscopy in live circulating tumor cells (CTCs) isolated from blood sample of a patient undergoing enzalutamide therapy.

Conclusion: Our data demonstrate that PCa cells resistant to enzalutamide show high degree of mitophagy of O2- mitochondria in autophagosomes. If this effect correlates with CTCs from blood collected from CRPC patients undergoing enzalutamide therapy, it can become a clinically useful method of identifying patients who are most likely to benefit from enzalutamide treatment.

Citation Format: Hirak S. Basu, Cynthia L. Schrieber, Jamie M. Sperger, Maryanne Naundorf, Ashley M. Weichman, Farideh Mehraein-Ghomi, Dawn R. Church, Joshua M. Lang, George Wilding. Mitophagy imparts enzalutamide resistance in prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2899. doi:10.1158/1538-7445.AM2015-2899

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.

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.

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 medications—93 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.

Initial results from ASSURE (E2805): Adjuvant sorafenib or sunitinib for unfavorable renal carcinoma, an ECOG-ACRIN-led, NCTN phase III trial

403

Background: Patients (pts) with locally advanced renal cell carcinoma (RCC) are not uniformly cured by resection. The pursuit of tolerable and effective adjuvant therapies led to this investigation of two oral agents that are widely effective in the metastatic setting. Methods: 1,943 pts with completely resected RCC (pT1b high grade to pT4 any grade N any) were stratified on risk (intermediate-high or very high), clear/non-clear histology, ECOG PS, and resection approach, and randomized equally to sunitinib daily for 4 of 6 wk cycle, sorafenib daily, or placebo, then treated for up to 1 year. The primary endpoint was disease-free survival (DFS). The study was designed to detect a 25% reduction in the hazard rate, corresponding to an improvement from 5.8 to 7.7 years median DFS. After accrual of 1322 pts, the starting dose was reduced and then individually titrated to mitigate the effect of pt discontinuation from treatment intolerance. Results: At an interim analysis conducted with 62% information, although no efficacy or futility boundaries were crossed, the Data Safety Monitoring Committee recommended release of results. Using a stratified log-rank test, there were no significant differences in DFS or overall survival between either of the experimental arms and placebo. The redesign reduced the discontinuation rate on the experimental arms from about 26% in pts starting at full dose to about 14% in pts starting at reduced dose. Most common grade ≥3 adverse events were hypertension (16%/16%/4%), hand-foot reaction (15%/33%/1%), Rash (2%/15%/<1%), and fatigue (17%/7%/3%) on sunitinib, sorafenib and placebo, respectively. (See Table.) Conclusions: In pts with locally advanced, resected RCC, adjuvant treatment with sorafenib or sunitinib should not be pursued. Dose titration reduced the treatment discontinuation rate; this finding may have relevance in other settings. Clinical trial information: NCT00326898. [Table: see text]

A phase I study to determine the maximum tolerated dose and safety of oral LR-103 (1α,24(S)Dihydroxyvitamin D2) in patients with advanced cancer

BACKGROUND

The objective of this study was to determine the maximum tolerated dose and safety of LR-103, a Vitamin D analogue, in patients with advanced cancer.

METHODS

In Step A, patients received oral LR-103 once daily in 14-day cycles with intra-patient dose escalation per accelerated dose escalation design. Dose limiting toxicity for Step A was defined as ≥grade 2 hypercalcemia and/or >grade 2 other toxicities. Starting dose was 5 µg/day. Step B used a 3+3 design starting at Step A maximum tolerated dose with 28-day cycles. Dose limiting toxicity was defined as ≥grade 3 hypercalcemia or any grade 3 or 4 non-hematologic toxicity, except hypercalciuria.

RESULTS

Twenty-one patients were enrolled; eight were treated in Step A. At dose level 3 (15 µg/day), two patients had dose limiting toxicity. One had grade 4 hyperuricemia. The other had grade 4 GGT plus grade 3 alkaline phosphatase, fatigue and urinary tract infection (UTI). Dose level 2 (10 µg/day) was the maximum tolerated dose for Step A and was starting dose for Step B. The dose was escalated to dose level 5 (30 µg/day) with a patient experiencing grade 3 dose limiting toxicity of hypercalcemia. The study was discontinued before reaching the maximum tolerated dose due to sponsor decision. Modest increases in serum osteocalcin and calcium and decrease in parathyroid hormone were noted. Best response was stable disease; four patients were on therapy for six months or longer.

CONCLUSION

Step A dose limiting toxicities limited accelerated dose escalation. The maximum tolerated dose of LR-103 was not reached prior to study termination and this agent is no longer being developed.

Real-time immune monitoring to guide plasmid DNA vaccination schedule targeting prostatic acid phosphatase in patients with castration-resistant prostate cancer

PURPOSE

We have previously reported that a DNA vaccine encoding prostatic acid phosphatase (PAP) could elicit PAP-specific T cells in patients with early recurrent prostate cancer. In the current pilot trial, we sought to evaluate whether prolonged immunization with regular booster immunizations, or "personalized" schedules of immunization determined using real-time immune monitoring, could elicit persistent, antigen-specific T cells, and whether treatment was associated with changes in PSA doubling time (PSA DT).

EXPERIMENTAL DESIGN

Sixteen patients with castration-resistant, nonmetastatic prostate cancer received six immunizations at 2-week intervals and then either quarterly (arm 1) or as determined by multiparameter immune monitoring (arm 2).

RESULTS

Patients were on study a median of 16 months; four received 24 vaccinations. Only one event associated with treatment >grade 2 was observed. Six of 16 (38%) remained metastasis-free at 2 years. PAP-specific T cells were elicited in 12 of 16 (75%), predominantly of a Th1 phenotype, which persisted in frequency and phenotype for at least 1 year. IFNγ-secreting T-cell responses measured by ELISPOT were detectable in 5 of 13 individuals at 1 year, and this was not statistically different between study arms. The overall median fold change in PSA DT from pretreatment to posttreatment was 1.6 (range, 0.6-7.0; P = 0.036).

CONCLUSIONS

Repetitive immunization with a plasmid DNA vaccine was safe and elicited Th1-biased antigen-specific T cells that persisted over time. Modifications in the immunization schedule based on real-time immune monitoring did not increase the frequency of patients developing effector and memory T-cell responses with this DNA vaccine.

Targeting androgen receptor and JunD interaction for prevention of prostate cancer progression

BACKGROUND

Multiple studies show that reactive oxygen species (ROS) play a major role in prostate cancer (PCa) development and progression. Previously, we reported an induction of Spermidine/Spermine N(1) -Acetyl Transferase (SSAT) by androgen-activated androgen receptor (AR)-JunD protein complex that leads to over-production of ROS in PCa cells. In our current research, we identify small molecules that specifically block AR-JunD in this ROS-generating metabolic pathway.

METHODS

A high throughput assay based on Gaussia Luciferase reconstitution was used to identify inhibitors of the AR-JunD interaction. Selected hits were further screened using a fluorescence polarization competitor assay to eliminate those that bind to the AR Ligand Binding Domain (LBD), in order to identify molecules that specifically target events downstream to androgen activation of AR. Eleven molecules were selected for studies on their efficacy against ROS generation and growth of cultured human PCa cells by DCFH dye-oxidation assay and DNA fluorescence assay, respectively. In situ Proximity Ligation Assay (PLA), SSAT promoter-luciferase reporter assay, and western blotting of apoptosis and cell cycle markers were used to study mechanism of action of the lead compound.

RESULTS

Selected lead compound GWARJD10 with EC(50) 10 μM against ROS production was shown to block AR-JunD interaction in situ as well as block androgen-induced SSAT gene expression at IC(50) 5 μM. This compound had no effect on apoptosis markers, but reduced cyclin D1 protein level.

CONCLUSIONS

Inhibitor of AR-JunD interaction, GWARJD10 shows promise for prevention of progression of PCa at an early stage of the disease by blocking growth and ROS production.

A phase I study of vorinostat in combination with bortezomib in patients with advanced malignancies

BACKGROUND

A phase I study to assess the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), pharmacokinetics (PK) and antitumor activity of vorinostat in combination with bortezomib in patients with advanced solid tumors.

METHODS

Patients received vorinostat orally once daily on days 1-14 and bortezomib intravenously on days 1, 4, 8 and 11 of a 21-day cycle. Starting dose (level 1) was vorinostat (400 mg) and bortezomib (0.7 mg/m(2)). Bortezomib dosing was increased using a standard phase I dose-escalation schema. PKs were evaluated during cycle 1.

RESULTS

Twenty-three patients received 57 cycles of treatment on four dose levels ranging from bortezomib 0.7 mg/m(2) to 1.5 mg/m(2). The MTD was established at vorinostat 400 mg daily and bortezomib 1.3 mg/m(2). DLTs consisted of grade 3 fatigue in three patients (1 mg/m(2),1.3 mg/m(2) and 1.5 mg/m(2)) and grade 3 hyponatremia in one patient (1.5 mg/m(2)). The most common grade 1/2 toxicities included nausea (60.9%), fatigue (34.8%), diaphoresis (34.8%), anorexia (30.4%) and constipation (26.1%). Objective partial responses were observed in one patient with NSCLC and in one patient with treatment-refractory soft tissue sarcoma. Bortezomib did not affect the PKs of vorinostat; however, the Cmax and AUC of the acid metabolite were significantly increased on day 2 compared with day 1.

CONCLUSIONS

This combination was generally well-tolerated at doses that achieved clinical benefit. The MTD was established at vorinostat 400 mg daily × 14 days and bortezomib 1.3 mg/m(2) on days 1, 4, 8 and 11 of a 21-day cycle.

A Phase I study of intermittently dosed vorinostat in combination with bortezomib in patients with advanced solid tumors

BACKGROUND

Accumulating evidence shows evidence of efficacy with the combination of vorinostat and bortezomib in solid tumors. We previously examined a once-daily continuous dosing schedule of vorinostat in combination with bortezomib which was well tolerated in cycles 1 and 2; however, there was concern regarding the tolerability through multiple cycles. This study was conducted to evaluate an intermittent dosing schedule of vorinostat with bortezomib.

METHODS

Vorinostat was initially administered orally twice daily on days 1-14 with bortezomib IV on days 1, 4, 8, and 11 of a 21 day cycle. Two DLTs (elevated ALT and fatigue) were observed at dose level 1, thus the protocol was amended to administer vorinostat intermittently twice daily on days 1-4 and 8-11.

RESULTS

29 patients were enrolled; 13 men and 16 women. Common cancer types included sarcoma, pancreatic, colorectal, GIST, and breast. The most common Grade 3-4 toxicities at any dose level included thrombocytopenia, fatigue, increased ALT, elevated INR, and diarrhea. DLTs in the intermittent dosing scheduled included thrombocytopenia and fatigue. The Cmax and AUC for the intermittent dosing regimen were similar to those observed in the daily dosing. In this heavily pretreated population, stable disease was observed in patients with sarcoma, colorectal adenocarcinoma and GIST.

CONCLUSIONS

The MTD was established at vorinostat 300 mg BID on days 1-4 and 8-11 and bortezomib 1.3 mg/m(2) IV on days 1, 4, 8, and 11 of a 21 day cycle. Tolerability was not improved with the intermittent dosing schedule of vorinostat when compared to continuous dosing.

Vorinostat in combination with bortezomib in patients with advanced malignancies directly alters transcription of target genes

INTRODUCTION

Vorinostat is a small molecule inhibitor of class I and II histone deacetylase enzymes which alters the expression of target genes including the cell cycle gene p21, leading to cell cycle arrest and apoptosis.

METHODS

Patients enrolled in a phase I trial were treated with vorinostat alone on day 1 and vorinostat and bortezomib in combination on day 9. Paired biopsies were obtained in eleven subjects. Blood samples were obtained on days 1 and 9 of cycle 1 prior to dosing and 2 and 6 h post-dosing in all 60 subjects. Gene expression of p21, HSP70, AKT, Nur77, ERB1, and ERB2 was evaluated in peripheral blood mononuclear cells and tissue samples. Chromatin immunoprecipitation of p21, HSP70, and Nur77 was also performed in biopsy samples.

RESULTS

In peripheral blood mononuclear cells, Nur77 was significantly and consistently decreased 2 h after vorinostat administration on both days 1 and 9, median ratio of gene expression relative to baseline of 0.69 with interquartile range 0.49-1.04 (p < 0.001); 0.28 (0.15-0.7) (p < 0.001), respectively, with more pronounced decrease on day 9, when patients received both vorinostat and bortezomib. p21, a downstream target of Nur77, was significantly decreased on day 9, 2 and 6 h after administration of vorinostat and bortezomib, 0.67 (0.41-1.03) (p < 0.01); 0.44 (0.25-1.3) (p < 0.01), respectively. The ChIP assay demonstrated a protein-DNA interaction, in this case interaction of Nur77, HSP70 and p21 with acetylated histone H3, at baseline and at day 9 after treatment with vorinostat in tissue biopsies in most patients.

CONCLUSION

Vorinostat inhibits Nur77 expression, which in turn may decrease p21 and AKT expression in PBMCs. The influence of vorinostat on target gene expression in tumor tissue was variable; however, most patients demonstrated interaction of acetylated H3 with Nur77, HSP70, and p21 which provides evidence of interaction with the transcriptionally active acetylated H3.

A randomized phase II trial evaluating different schedules of zoledronic acid on bone mineral density in patients with prostate cancer beginning androgen deprivation therapy

OBJECTIVE

To assess the effects of timing and schedule of zoledronic acid (ZA) administration on bone mineral density (BMD) in patients beginning androgen deprivation therapy (ADT) for the treatment of recurrent prostate cancer.

PATIENTS AND METHODS

In this randomized, 3-arm trial, we evaluated changes in BMD after 3 different ZA administration schedules in men with recurrent prostate cancer who were beginning ADT. Forty-four patients were enrolled and randomized to receive a single dose of ZA given 1 week before beginning ADT (arm 1), a single dose of ZA given 6 months after beginning ADT (arm 2), or monthly administration of ZA starting 6 months after beginning ADT, for a total of 6 doses (arm 3).

RESULTS

Patients who received ZA before ADT had a significant improvement in BMD at the total proximal femur and trochanter after 6 months compared with the other groups. In addition, only patients in the arm that received multiple doses improved lumbar spine BMD while on ADT, with these findings persisting to 24 months. However, this group also experienced more grade 1 adverse events.

CONCLUSIONS

Analysis of these data suggests that ZA administration before initiation of ADT was superior to treatment 6 months after starting ADT in maintaining BMD. In addition, monthly ZA administration can increase BMD above baseline but is associated with more adverse events. Further study is needed to examine whether the timing and frequency of ZA therapy in patients on ADT can reduce fracture risk.

A non-comparative randomized phase II study of 2 doses of ATN-224, a copper/zinc superoxide dismutase inhibitor, in patients with biochemically recurrent hormone-naïve prostate cancer

OBJECTIVE

ATN-224 (choline tetrathiomolybdate) is an oral Cu(2+)/Zn(2+)-superoxide dismutase 1 (SOD1) inhibitor with preclinical antitumor activity. We hypothesized that ATN-224 may induce antitumor effects as an antiangiogenic agent at low dose-levels while possessing direct antitumor activity at higher dose-levels. The objective of this study was to screen its clinical activity in patients with biochemically recurrent hormone-naïve prostate cancer.

METHODS

Biochemically-recurrent prostate cancer patients with prostate specific antigen doubling times (PSADT) < 12 months, no radiographic evidence of metastasis, and no hormonal therapy within 6 months (with serum testosterone levels > 150 ng/dl) were eligible. ATN-224 was administered at 2 dose-levels, 300 mg (n = 23) or 30 mg (n = 24) daily, by way of randomization. PSA progression was defined as a ≥ 50% increase (and >5 ng/ml) in PSA from baseline or post-treatment nadir. Endpoints included the proportion of patients who were free of PSA progression at 24 weeks, changes in PSA slope/PSADT, and safety. The study was not powered to detect differences between the 2 treatment groups.

RESULTS

At 24 weeks, 59% (95% CI 33%-82%) of men in the low-dose arm and 45% (95% CI 17%-77%) in the high-dose arm were PSA progression-free. Median PSA progression-free survival was 30 weeks (95% CI 21-40(+)) and 26 weeks (95% CI 24-39(+)) in the low-dose and high-dose groups, respectively. Pre- and on-treatment PSA kinetics analyses showed a significant mean PSA slope decrease (P = 0.006) and a significant mean PSADT increase (P = 0.032) in the low-dose arm only. Serum ceruloplasmin levels, a biomarker for ATN-224 activity, were lowered in the high-dose group, but did not correlate with PSA changes.

CONCLUSIONS

Low-dose ATN-224 (30 mg daily) may have biologic activity in men with biochemically-recurrent prostate cancer, as suggested by an improvement in PSA kinetics. However, the clinical significance of PSA kinetics changes in this patient population remains uncertain. The absence of a dose-response effect also reduces enthusiasm, and there are currently no plans to further develop this agent in prostate cancer.

Phase II open label, multi-center clinical trial of modulation of intermediate endpoint biomarkers by 1α-hydroxyvitamin D2 in patients with clinically localized prostate cancer and high grade pin

BACKGROUND

Prostate cancer is the most common malignancy and second leading cause of cancer related deaths in American men supporting the study of prostate cancer chemoprevention. Major risk factors for this disease have been associated with low serum levels of vitamin D. Here, we evaluate the biologic activity of a less calcemic vitamin D analog 1α-hydroxyvitamin D2 [1α-OH-D2] (Bone Care International, Inc.) in patients with prostate cancer and high grade prostatic intraepithelial neoplasia (HG PIN).

METHODS

Patients with clinically organ-confined prostate cancer and HG PIN were randomized to 1α-OH-D2 versus placebo for 28 days prior to radical prostatectomy. Intermediate endpoint biomarkers included serum vitamin D metabolites, TGFß 1/2, free/total PSA, IGF-1, IGFBP-3, bFGF, and VEGF. Tissue endpoints included histology, MIB-1 and TUNEL staining, microvessel density and factor VIII staining, androgen receptor and PSA, vitamin D receptor expression and nuclear morphometry.

RESULTS

The 1α-OH-D2 vitamin D analog was well tolerated and could be safely administered with good compliance and no evidence of hypercalcemia over 28 days. While serum vitamin D metabolite levels only slightly increased, evidence of biologic activity was observed with significant reductions in serum PTH levels. TGF-ß2 was the only biomarker significantly altered by vitamin D supplementation. Whether reduced TGF-ß2 levels in our study is an early indicator of response to vitamin D remains unclear.

CONCLUSIONS

While further investigation of vitamin D may be warranted based on preclinical studies, results of the present trial do not appear to justify evaluation of 1α-OH-D2 in larger clinical prostate cancer prevention studies.

A phase I study of MK-2206 in combination with lapatinib in patients (pts) with advanced solid tumors

2607

Background: The AKT protein kinase is a key mediator of signaling in the human epidermal growth factor receptor-2 (HER2) pathway. HER2 inhibition can result in feedback regulation of signaling, leading to high AKT activity. Preclinical studies demonstrate activity of combined HER2 and AKT inhibition. Lapatinib is an oral tyrosine kinase inhibitor of HER2. MK-2206 is an oral selective inhibitor of AKT with a maximum tolerated dose (MTD) of 60mg qod. Both agents cause rash and diarrhea. This study was designed to determine the MTD, dose limiting toxicities (DLTs), adverse events (AEs), clinical activity and pharmacokinetic (PK) parameters of the combination. Methods: This phase I study evaluated the safety of MK-2206 (30-60 mg qod) and lapatinib (1000-1500 mg qd) continuously. Cycles were 28 days, except cycle 1 (35 days), due to a 1 week MK-2206 lead-in to evaluate for PK interactions. Because of the continuous nature of therapy, protocol-specified intolerable grade 2 AEs were considered DLTs during cycle 1. Results: 23 pts (median age 59 [range 22-72];15 female:8 male) were enrolled. The most common malignancies were colorectal (8 pts), lung (4 pts), and breast (3 pts). 4 pts were unevaluable per protocol; 19 evaluable pts were on study a median of 8 weeks (range 3-35). 3 pts experienced DLTs. At dose level one, 1 pt had grade (gr) 3 hyponatremia and fatigue. At dose level four, 1 pt had gr 4 hyponatremia, gr 3 rash and hypocalcemia and 1 pt had intolerable gr 2 mucositis with delivery of <75% of drug. The most common AEs at least possibly related to therapy included diarrhea (gr 3-4 in 3 pts; gr 1-2 in 16 pts), nausea (gr 3 in 2 pts; gr 1-2 in 14 pts) and rash (gr 3 in 2 pts; gr 1-2 in 12 pts). The MTD was 45mg po qod of MK-2206 with 1500 mg po qd of lapatinib, exceeding biologically active doses for each agent. One pt with adrenal cortical carcinoma was on study for 6 months with stable disease (SD) and 1 pt with colorectal cancer was on study for 5 months with significant tumor marker decline and SD. PK analyses are ongoing. Conclusions: MK-2206 in combination with lapatinib is well-tolerated at biologically active single agent doses. Anti-tumor activity will be evaluated further in a dose expansion cohort in pts with advanced HER2-positive breast cancer. Clinical trial information: NCT01245205.

Final results of the phase I trial of niraparib (MK4827), a poly(ADP)ribose polymerase (PARP) inhibitor incorporating proof of concept biomarker studies and expansion cohorts involving BRCA1/2 mutation carriers, sporadic ovarian, and castration resistant prostate cancer (CRPC)

2513

Background: Niraparib(N) is an oral, potent PARP1/2 inhibitor that induces synthetic lethality in BRCA1/2 deficient tumors. PARP is also implicated in transcription regulated by the androgen receptor (AR) and rearranged ETS genes; key targets in CRPC. Methods: Dose-escalation was enriched for BRCA1/2mutation carriers (BRCA-MCs). Two MTD expansion cohorts were undertaken in patients (pts) with sporadic high grade serous ovarian cancer (HGSOC) and CRPC. In CRPC pts, archival tissue and circulating tumor cells (CTC) were analyzed for PTEN deletion and ETS gene rearrangements. Results: 100 pts [ovary (49), CRPC (23), breast (12) others (16)], received N at 10 dose levels: 30mg to 400mg daily (od), continuously. Grade (G) 4 thrombocytopenia was dose limiting at 400mg od; MTD was established at 300mg od. Drug-related toxicities were G1-2 reversible anemia (48%), fatigue (42%), nausea (42%), thrombocytopenia (35%), anorexia (27%), neutropenia (24%), constipation (23%), and vomiting (20%). PKs were dose proportional with a mean elimination t1/2of 40 hours. Peripheral blood mononuclear cells had >50% PARP inhibition from 80 mg od. gH2AX foci formation, a marker of DNA damage, was seen in CTCs. Antitumor activity occurred from 60mg od with RECIST and/or CA125 partial responses (PR) in 9/20 (45%) BRCA-MC ovarian cancer pts and 2/4 (50%) BRCA-MC breast cancer pts. Platinum-sensitive vs resistant BRCA-MC HGSOC response rate was 60% vs 33% with median time for responding pts of 429 and 340 days, respectively. In sporadic HGSOC, there were 2/3 PRs in platinum-sensitive pts, and 3/20 PRs plus 4/20 stable disease (SD) >16 weeks in platinum resistant pts. In CRPC, symptomatic benefit and SD >6 months (median 9 months) was seen in 9/21 (43%) pts treated at MTD. CTC declines of >30% (median 80%; range 36%-92%) were observed in 7/10 (70%) pts with evaluable CTC counts (≥5 cells/ 7.5mL blood). Conclusions: Niraparib was well tolerated and has promising antitumor activity in BRCA-MCs, sporadic HGSOC and CRPC. Clinical trial information: NCT0074902.

Intermittent versus continuous androgen deprivation in prostate cancer

BACKGROUND

Castration resistance occurs in most patients with metastatic hormone-sensitive prostate cancer who are receiving androgen-deprivation therapy. Replacing androgens before progression of the disease is hypothesized to prolong androgen dependence.

METHODS

Men with newly diagnosed, metastatic, hormone-sensitive prostate cancer, a performance status of 0 to 2, and a prostate-specific antigen (PSA) level of 5 ng per milliliter or higher received a luteinizing hormone-releasing hormone analogue and an antiandrogen agent for 7 months. We then randomly assigned patients in whom the PSA level fell to 4 ng per milliliter or lower to continuous or intermittent androgen deprivation, with patients stratified according to prior or no prior hormonal therapy, performance status, and extent of disease (minimal or extensive). The coprimary objectives were to assess whether intermittent therapy was noninferior to continuous therapy with respect to survival, with a one-sided test with an upper boundary of the hazard ratio of 1.20, and whether quality of life differed between the groups 3 months after randomization.

RESULTS

A total of 3040 patients were enrolled, of whom 1535 were included in the analysis: 765 randomly assigned to continuous androgen deprivation and 770 assigned to intermittent androgen deprivation. The median follow-up period was 9.8 years. Median survival was 5.8 years in the continuous-therapy group and 5.1 years in the intermittent-therapy group (hazard ratio for death with intermittent therapy, 1.10; 90% confidence interval, 0.99 to 1.23). Intermittent therapy was associated with better erectile function and mental health (P<0.001 and P=0.003, respectively) at month 3 but not thereafter. There were no significant differences between the groups in the number of treatment-related high-grade adverse events.

CONCLUSIONS

Our findings were statistically inconclusive. In patients with metastatic hormone-sensitive prostate cancer, the confidence interval for survival exceeded the upper boundary for noninferiority, suggesting that we cannot rule out a 20% greater risk of death with intermittent therapy than with continuous therapy, but too few events occurred to rule out significant inferiority of intermittent therapy. Intermittent therapy resulted in small improvements in quality of life. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT00002651.).

Axitinib in metastatic renal cell carcinoma: results of a pharmacokinetic and pharmacodynamic analysis

Axitinib is a potent and selective inhibitor of vascular endothelial growth factor receptors 1, 2, and 3, approved for second-line therapy for advanced renal cell carcinoma (RCC). Axitinib population pharmacokinetic and pharmacokinetic/pharmacodynamic relationships were evaluated. Using nonlinear mixed effects modeling with pooled data from 383 healthy volunteers, 181 patients with metastatic RCC, and 26 patients with other solid tumors in 17 trials, the disposition of axitinib was best described by a 2-compartment model with first-order absorption and a lag time, with estimated mean systemic clearance (CL) of 14.6 L/h and central volume of distribution (V(c)) of 47.3 L. Of 12 covariates tested, age over 60 years and Japanese ethnicity were associated with decreased CL, whereas V(c) increased with body weight. However, the magnitude of predicted changes in exposure based on these covariates does not warrant dose adjustments. Multivariate Cox proportional hazard regression and logistic regression analyses showed that higher exposure and diastolic blood pressure were independently associated with longer progression-free and overall survivals and higher probability of partial response in metastatic RCC patients. These findings support axitinib dose titration to increase plasma exposure in patients who tolerate axitinib, and also demonstrate diastolic blood pressure as a potential marker of efficacy.

Overall survival (OS) and safety of dasatinib/docetaxel versus docetaxel in patients with metastatic castration-resistant prostate cancer (mCRPC): Results from the randomized phase III READY trial

LBA8

Background: SRC kinases may contribute to androgen independence of mCRPC.Dasatinib (DAS) inhibits tyrosine kinases including SRC kinases with preclinical evidence for antimetastatic activity, inhibition of osteoclast function in tumor microenvironment, and synergistic activity with docetaxel (D). In phase I/II trials of mCRPC patients (pts), DAS in combination with D had an acceptable safety profile with objective response rates (ORR) improved over historical data and decreased levels of bone turnover markers. Methods: READY was a multinational, randomized, double-blinded, placebo-controlled, phase III study. Pts with mCRPC (n = 1,522) were randomized (1:1) to receive either D 75 mg/m2q3wk + prednisone with double-blinded DAS 100 mg qd (DAS/D, n = 762) or placebo (PBO/D, n = 760). Primary endpoint was overall survival (OS). Secondary endpoints were ORR, time to first skeletal-related event (TFSRE), time to prostate-specific antigen progression (TPSAP), urinary N-telopeptide (uNTX) reduction, pain reduction, progression-free survival (PFS), and safety. Results: No OS difference between DAS/D and PBO/D (median, 21.5 vs. 21.2 mos; hazard ratio [HR], 0.99; log-rank P = 0.90) was observed. Results of secondary endpoints for DAS/D vs. PBO/D were: ORR (30.5 vs. 31.9%); TFSRE (median, not reached vs. 31.1 mos; HR, 0.81 [95% CI, 0.64-1.02]); uNTX reduction (66.0 vs. 60.6%); PFS (median, 11.8 vs. 11.1 mos; HR, 0.92); TPSAP (median, 8.0 vs. 7.6 mos; HR, 0.91), and pain reduction (66.6 vs. 71.5%). Twenty-three percent of DAS/D and 14% of PBO/D pts received therapy for <3 mos. Most common AEs in DAS/D arm included diarrhea, fatigue, alopecia, and nausea. Grade 3-4 AEs of interest for DAS/D vs. PBO/D included anemia (8.0 vs.5.9%), neutropenia (6.2 vs. 5.5%), hypocalcemia (3.5 vs.3.1%), GI bleeding (2.6 vs.1.3%), and pleural effusion (1.3 vs. 0.4%). Conclusions: The addition of DAS to standard-of-care chemotherapy in mCRPC pts did not improve OS. There was a modest reduction in the risk of TFSRE with DAS/D vs. PBO/D. With a median follow-up of 19 mos of 761 DAS/D-treated pts, no unexpected toxicities for DAS were observed. Clinical trial information: NCT00744497.