Survival in Patients With De Novo Metastatic Prostate Cancer

This cross-sectional study investigates trends in overall survival among patients with newly diagnosed metastatic prostate cancer in 2 national registries in the United States.

Sarcomatoid Urothelial Carcinoma Is Associated With Limited Response to Neoadjuvant Chemotherapy and Poor Oncologic Outcomes After Radical Cystectomy

INTRODUCTION

To examine oncologic outcomes and response to neoadjuvant chemotherapy (NAC) in patients with sarcomatoid urothelial carcinoma (SUC) treated with radical cystectomy (RC).

MATERIALS AND METHODS

We retrospectively queried our institutional database (2003-18) and Surveillance, Epidemiology, and End Results (SEER)-Medicare (2004-2015) for patients with cT2-4, N0-2, M0 SUC and conventional UC (CUC) treated with RC. Clinicopathologic characteristics were described using descriptive statistics (t test, χ2-test and log-rank-test for group comparison). Overall (OS) and recurrence-free-survival (RFS) after RC were estimated with the Kaplan Meier method and associations with OS were evaluated with Cox proportional hazards models.

RESULTS

We identified 38 patients with SUC and 287 patients with CUC in our database, and 190 patients with SUC in SEER-Medicare. In the institutional cohort, patients with SUC versus CUC had higher rates of pT3/4 stage (66% vs. 35%, P < 0.001), lower rates of ypT0N0 (6% vs. 35%, P = .02), and worse median OS (17.5 vs. 120 months, P < .001). Further, patients with SUC in the institutional versus SEER-Medicare cohort had similar median OS (17.5 vs. 21 months). In both cohorts, OS was comparable between patients with SUC undergoing NAC+RC vs. RC alone (17.5 vs. 18.4 months, P = .98, institutional cohort; 24 vs. 20 months, P = .56, SEER cohort). In Cox proportional hazards models for the institutional RC cohort, SUC was independently associated with worse OS (HR 2.3, CI 1.4-3.8, P = .001).

CONCLUSION

SUC demonstrates poor pathologic response to NAC and worse OS compared with CUC, with no OS benefit associated with NAC. A unique pattern of rapid abdominopelvic cystic recurrence was identified.

Nucleosome Patterns in Circulating Tumor DNA Reveal Transcriptional Regulation of Advanced Prostate Cancer Phenotypes

Advanced prostate cancers comprise distinct phenotypes, but tumor classification remains clinically challenging. Here, we harnessed circulating tumor DNA (ctDNA) to study tumor phenotypes by ascertaining nucleosome positioning patterns associated with transcription regulation. We sequenced plasma ctDNA whole genomes from patient-derived xenografts representing a spectrum of androgen receptor active (ARPC) and neuroendocrine (NEPC) prostate cancers. Nucleosome patterns associated with transcriptional activity were reflected in ctDNA at regions of genes, promoters, histone modifications, transcription factor binding, and accessible chromatin. We identified the activity of key phenotype-defining transcriptional regulators from ctDNA, including AR, ASCL1, HOXB13, HNF4G, and GATA2. To distinguish NEPC and ARPC in patient plasma samples, we developed prediction models that achieved accuracies of 97% for dominant phenotypes and 87% for mixed clinical phenotypes. Although phenotype classification is typically assessed by IHC or transcriptome profiling from tumor biopsies, we demonstrate that ctDNA provides comparable results with diagnostic advantages for precision oncology.

SIGNIFICANCE

This study provides insights into the dynamics of nucleosome positioning and gene regulation associated with cancer phenotypes that can be ascertained from ctDNA. New methods for classification in phenotype mixtures extend the utility of ctDNA beyond assessments of somatic DNA alterations with important implications for molecular classification and precision oncology. This article is highlighted in the In This Issue feature, p. 517.

Surrogate Endpoints as Predictors of Overall Survival in Metastatic Urothelial Cancer: A Trial-level Analysis

Background

Surrogate endpoints (SEs), such as progression-free survival (PFS) and objective response rate (ORR), are frequently used in clinical trials. The relationship between SEs and overall survival (OS) has not been well described in metastatic urothelial cancer (MUC).

Objective

We evaluated trial-level data to assess the relationship between SEs and OS. We hypothesize a moderate surrogacy relationship between both PFS and ORR with OS.

Design setting and participants

We systematically reviewed phase 2/3 trials in MUC with two or more treatment arms, and report PFS and/or ORR, and OS.

Outcome measurements and statistical analysis

Linear regression was performed, and the coefficient of determination (R²) and surrogate threshold effect (STE) estimate were determined between PFS/ORR and OS.

Results and limitations

Of 3791 search results, 59 trials and 62 comparisons met the inclusion criteria. Of the 53 trials that reported PFS, 31 (58%) reported proportional hazard regression for PFS and OS. Linear regression across trials demonstrated an R² of 0.60 between hazard ratio (HR) for PFS (HR^PFS) and HR for OS (HR^OS), and an STE of 0.41. Linear regression of ΔPFS (median PFS in months of the treatment arm - that of the control arm) and ΔOS demonstrated an R² of 0.12 and an STE of 14.1 mo. Thirty trials reported ORRs. Linear regression for ORR^ratio and HR^OS among all trials found an R² of 0.08; an STE of 95% was not reached at any value and ΔORR and HR^OS similarly demonstrated a poor correlation with an R² value of 0.03.

Conclusions

PFS provides only a moderate level of surrogacy for OS; An HR^PFS of ≤0.41 provides 95% confidence of OS improvement. ORR is weakly correlated with OS and should be de-emphasized in MUC clinical trials. When PFS is discussed, proportional hazard regression should be reported.

Patient summary

We examined the relationship between surrogate endpoints, common outcomes in clinical trials, with survival in urothelial cancer trials. Progression-free survival is moderately correlated, while objective response rate had a poor correlation with survival and should be de-emphasized as a primary endpoint.

Circulating and Intratumoral Adrenal Androgens Correlate with Response to Abiraterone in Men with Castration-Resistant Prostate Cancer

PURPOSE

In metastatic castration-resistant prostate cancer (mCRPC) low serum androgens prior to starting abiraterone acetate (AA) is associated with more rapid progression. We evaluated the effect of AA on androgens in castration-resistant prostate cancer (CRPC) metastases and associations of intratumoral androgens with response.

EXPERIMENTAL DESIGN

We performed a phase II study of AA plus prednisone in mCRPC. The primary outcome was tissue testosterone at 4 weeks. Exploratory outcomes were association of steroid levels and genomic alterations with response, and escalating AA to 2,000 mg at progression.

RESULTS

Twenty-nine of 30 men were evaluable. Testosterone in metastatic biopsies became undetectable at 4 weeks (P < 0.001). Serum and tissue dehydroepiandrosterone sulfate (DHEAS) remained detectable in many patients and was not increased at progression. Serum and tissue DHEAS in the lowest quartile (pretreatment), serum DHEAS in the lowest quartile (4 weeks), and undetectable tissue DHEAS (on-therapy) associated with rapid progression (20 vs. 48 weeks, P = 0.0018; 20 vs. 52 weeks, P = 0.0003; 14 vs. 40 weeks, P = 0.0001; 20 vs. 56 weeks, P = 0.02, respectively). One of 16 men escalating to 2,000 mg had a 30% PSA decline; 13 developed radiographic progression by 12 weeks. Among patients with high serum DHEAS at baseline, wild-type (WT) PTEN status associated with longer response (61 vs. 33 weeks, P = 0.02).

CONCLUSIONS

Low-circulating adrenal androgen levels are strongly associated with an androgen-poor tumor microenvironment and with poor response to AA. Patients with CRPC with higher serum DHEAS levels may benefit from dual androgen receptor (AR)-pathway inhibition, while those in the lowest quartile may require combinations with non-AR-directed therapy.

Hormonal intervention for the treatment of veterans with COVID-19 requiring hospitalization (HITCH): a multicenter, phase 2 randomized controlled trial of best supportive care vs best supportive care plus degarelix: study protocol for a randomized controlled trial

Background

Therapeutic targeting of host-cell factors required for SARS-CoV-2 entry is an alternative strategy to ameliorate COVID-19 severity. SARS-CoV-2 entry into lung epithelium requires the TMPRSS2 cell surface protease. Pre-clinical and correlative data in humans suggest that anti-androgenic therapies can reduce the expression of TMPRSS2 on lung epithelium. Accordingly, we hypothesize that therapeutic targeting of androgen receptor signaling via degarelix, a luteinizing hormone-releasing hormone (LHRH) antagonist, will suppress COVID-19 infection and ameliorate symptom severity.

Methods

This is a randomized phase 2, placebo-controlled, double-blind clinical trial in 198 patients to compare efficacy of degarelix plus best supportive care versus placebo plus best supportive care on improving the clinical outcomes of male Veterans who have been hospitalized due to COVID-19. Enrolled patients must have documented infection with SARS-CoV-2 based on a positive reverse transcriptase polymerase chain reaction result performed on a nasopharyngeal swab and have a severity of illness of level 3–5 (hospitalized but not requiring invasive mechanical ventilation). Patients stratified by age, history of hypertension, and severity are centrally randomized 2:1 (degarelix: placebo). The composite primary endpoint is mortality, ongoing need for hospitalization, or requirement for mechanical ventilation at 15 after randomization. Important secondary endpoints include time to clinical improvement, inpatient mortality, length of hospitalization, duration of mechanical ventilation, time to achieve a normal temperature, and the maximum severity of COVID-19 illness. Exploratory analyses aim to assess the association of cytokines, viral load, and various comorbidities with outcome. In addition, TMPRSS2 expression in target tissue and development of anti-viral antibodies will also be investigated.

Discussion

In this trial, we repurpose the FDA approved LHRH antagonist degarelix, commonly used for prostate cancer, to suppress TMPRSS2, a host cell surface protease required for SARS-CoV-2 cell entry. The objective is to determine if temporary androgen suppression with a single dose of degarelix improves the clinical outcomes of patients hospitalized due to COVID-19.

Trial registration

ClinicalTrials.gov NCT04397718. Registered on May 21, 2020

Phase II Multicenter Study of Enzalutamide in Metastatic Castration-Resistant Prostate Cancer to Identify Mechanisms Driving Resistance

PURPOSE

Enzalutamide is a second-generation androgen receptor (AR) inhibitor that has improved overall survival (OS) in metastatic castration-resistant prostate cancer (CRPC). However, nearly all patients develop resistance. We designed a phase II multicenter study of enzalutamide in metastatic CRPC incorporating tissue and blood biomarkers to dissect mechanisms driving resistance.

PATIENTS AND METHODS

Eligible patients with metastatic CRPC underwent a baseline metastasis biopsy and then initiated enzalutamide 160 mg daily. A repeat metastasis biopsy was obtained at radiographic progression from the same site when possible. Blood for circulating tumor cell (CTC) analysis was collected at baseline and progression. The primary objective was to analyze mechanisms of resistance in serial biopsies. Whole-exome sequencing was performed on tissue biopsies. CTC samples underwent RNA sequencing.

RESULTS

A total of 65 patients initiated treatment, of whom 22 (33.8%) had received prior abiraterone. Baseline biopsies were enriched for alterations in AR (mutations, amplifications) and tumor suppression genes (PTEN, RB1, and TP53), which were observed in 73.1% and 92.3% of baseline biopsies, respectively. Progression biopsies revealed increased AR amplifications (64.7% at progression vs. 53.9% at baseline) and BRCA2 alterations (64.7% at progression vs. 38.5% at baseline). Genomic analysis of baseline and progression CTC samples demonstrated increased AR splice variants, AR-regulated genes, and neuroendocrine markers at progression.

CONCLUSIONS

Our results demonstrate that a large proportion of enzalutamide-treated patients have baseline and progression alterations in the AR pathway and tumor suppressor genes. We demonstrate an increased number of BRCA2 alterations post-enzalutamide, highlighting the importance of serial tumor sampling in CRPC.

Impact of mutations in homologous recombination repair genes on treatment outcomes for metastatic castration resistant prostate cancer

INTRODUCTION

A significant proportion of patients with metastatic castration-resistant prostate cancer (mCRPC) harbor mutations in homologous recombination (HR) repair genes, with some of these mutations associating with increased tumor susceptibility to poly(ADP-ribose) polymerase (PARP) inhibitors and platinum-based chemotherapy. While mutations in some HR repair genes (e.g., BRCA1/2) have been associated with a more aggressive clinical course, prior studies correlating HR mutational status with treatment response to androgen receptor (AR) signaling inhibitors (ARSIs) or taxane-based chemotherapy have yielded conflicting results.

METHODS

We conducted a single-center retrospective analysis to assess clinical outcomes to conventional, regulatory-approved therapies in mCRPC patients with somatic (monoallelic and biallelic) and/or germline HR repair mutations compared to patients without alterations as determined by clinical-grade next-generation sequencing assays. The primary endpoint was PSA30/PSA50 response, defined as ≥30%/≥50% prostate-specific antigen (PSA) reduction from baseline. Secondary endpoints of PSA progression-free survival (pPFS) and clinical/radiographic progression-free survival (crPFS) were estimated using Kaplan-Meier methods.

RESULTS

A total of 90 consecutively selected patients were included in this analysis, of which 33 (37%) were identified to have HR repair gene mutations. Age, race, Gleason score, prior surgery, and receipt of prior radiation therapy were comparable between carriers and non-carriers. There was no evidence that PSA30/PSA50 differed by HR gene mutational status. Median pPFS and crPFS ranged 3-14 months across treatment modalities, but there was no evidence either differed by HR gene mutational status (all p>0.05). There was also no difference in outcomes between those with BRCA2 or PALB2 mutations (n = 17) compared to those without HR repair mutations.

CONCLUSION

HR gene mutational status was associated with comparable clinical outcomes following treatment with ARSIs or taxane-based chemotherapy. Additional prospective studies are needed to confirm these findings.

CDK12-Mutated Prostate Cancer: Clinical Outcomes With Standard Therapies and Immune Checkpoint Blockade

PURPOSE

Translational studies have shown that CDK12 mutations may delineate an immunoresponsive subgroup of prostate cancer, characterized by high neo-antigen burden. Given that these mutations may define a clinically distinct subgroup, we sought to describe outcomes to standard drugs and checkpoint inhibitors (CPI).

PATIENTS AND METHODS

Clinical data from consecutive patients with CDK12 mutations were retrospectively collected from 7 centers. Several clinical-grade sequencing assays were used to assess CDK12 status. Descriptive statistics included PSA50 response rate (≥ 50% decline in prostate-specific antigen from baseline) and clinical/radiographic progression-free survival (PFS).

RESULTS

Of 52 patients with CDK12-mutated prostate cancer, 27 (52%) had detected biallelic CDK12 alterations. At diagnosis, 44 (88%) had Gleason grade group 4-5, 52% had T3-T4, and 14 (27%) had M1 disease. Median follow-up was 8.2 years (95% CI, 5.6 to 11.1 years), and 49 (94%) developed metastatic disease. Median overall survival from metastasis was 3.9 years (95% CI, 3.2 to 8.1 years). Unconfirmed PSA50 response rates to abiraterone and enzalutamide in the first-line castration-resistant prostate cancer setting were 11 of 17 (65%) and 9 of 12 (75%), respectively. Median PFS on first-line abiraterone and enzalutamide was short, at 8.2 months (95% CI, 6.6 to 12.6 months) and 10.6 months (95% CI, 10.2 months to not reached), respectively. Nineteen patients received CPI therapy. PSA50 responses to CPI were noted in 11%, and PFS was short; however, the estimated 9-month PFS was 23%. PFS was higher in chemotherapy-näıve versus chemotherapypretreated patients (median PFS: not reached v 2.1 months, P = .004).

CONCLUSION

CDK12 mutations define an aggressive prostate cancer subgroup, with a high rate of metastases and short overall survival. CPI may be effective in a minority of these patients, and exploratory analysis supports using anti-programmed cell death protein 1 drugs early. Prospective studies testing CPI in this subset of patients with prostate cancer are warranted.

Clinical determinants for successful circulating tumor DNA analysis in prostate cancer

BACKGROUND

Plasma-based cell-free DNA is an attractive biospecimen for assessing somatic mutations due to minimally-invasive real-time sampling. However, next generation sequencing (NGS) of cell-free DNA (cfDNA) may not be appropriate for all patients with advanced prostate cancer (PC).

METHODS

Blood was obtained from advanced PC patients for plasma-based sequencing. UW-OncoPlex, a ∼2 Mb multi-gene NGS panel performed in the CLIA/CAP environment, was optimized for detecting cfDNA mutations. Tumor tissue and germline samples were sequenced for comparative analyses. Multivariate logistic regression was performed to determine the clinical characteristic associated with the successful detection of somatic cfDNA alterations (ie detection of at least one clearly somatic PC mutation).

RESULTS

Plasma for cfDNA sequencing was obtained from 93 PC patients along with tumor tissue (N = 67) and germline (N = 93) controls. We included data from 76 patients (72 prostate adenocarcinoma; 4 variant histology PC) in the analysis. Somatic DNA aberrations were detected in 34 cfDNA samples from patients with prostate adenocarcinoma. High PSA level, high tumor volume, and castration-resistance were significantly associated with successful detection of somatic cfDNA alterations. Among samples with somatic mutations detected, the cfDNA assay detected 93/102 (91%) alterations found in tumor tissue, yielding a clustering-corrected sensitivity of 92% (95% confidence interval 88-97%). All germline pathogenic variants present in lymphocyte DNA were also detected in cfDNA (N = 12). Somatic mutations from cfDNA were detected in 30/33 (93%) instances when PSA was >10 ng/mL.

CONCLUSIONS

Disease burden, including a PSA >10 ng/mL, is strongly associated with detecting somatic mutations from cfDNA specimens.

Genomic Characterization of Prostatic Ductal Adenocarcinoma Identifies a High Prevalence of DNA Repair Gene Mutations

PURPOSE

Ductal prostate cancer (dPC) is a rare variant of prostatic adenocarcinoma associated with poor outcomes. Although its histopathologic features are well characterized, the underlying molecular hallmarks of this aggressive subtype are not well described. We sought to provide a comprehensive overview of the spectrum of mutations associated with dPC.

METHODS

Three case series across multiple institutions were assembled. All patients had a diagnosis of dPC, and histopathologic classification was confirmed by an expert genitourinary pathologist. Case series 1 included men who were prospectively enrolled in a tumor sequencing study at the University of Washington (n = 22). Case series 2 and 3 included archival samples from men treated at Johns Hopkins Hospital (n = 21) and University of Calgary (n = 8), respectively. Tumor tissue was sequenced on a targeted next-generation sequencing assay, UW-OncoPlex, according to previously published methods. The frequency of pathogenic/likely pathogenic mutations are reported.

RESULTS

Overall, 25 patients (49%) had at least one DNA damage repair gene alteration, including seven (14%) with a mismatch repair gene mutation and 16 (31%) with a homologous repair mutation. Germline autosomal dominant mutations were confirmed or suspected in 10 patients (20%). Activating mutations in the PI3K pathway (n = 19; 37%), WNT pathway (n = 16; 31%), and MAPK pathway (n = 8; 16%) were common.

CONCLUSION

This study strongly suggests that dPCs are enriched for actionable mutations, with approximately 50% of patients demonstrating DNA damage repair pathway alteration(s). Patients with dPC should be offered next-generation sequencing to guide standard-of-care treatment (eg, immune checkpoint inhibitors) or triaged toward an appropriate clinical trial (eg, poly [ADP-ribose] polymerase inhibitors).

Association of Tissue Abiraterone Levels and SLCO Genotype with Intraprostatic Steroids and Pathologic Response in Men with High-Risk Localized Prostate Cancer

Purpose: Germline variation in solute carrier organic anion (SLCO) genes influences cellular steroid uptake and is associated with prostate cancer outcomes. We hypothesized that, due to its steroidal structure, the CYP17A inhibitor abiraterone may undergo transport by SLCO-encoded transporters and that SLCO gene variation may influence intracellular abiraterone levels and outcomes.Experimental Design: Steroid and abiraterone levels were measured in serum and tissue from 58 men with localized prostate cancer in a clinical trial of LHRH agonist plus abiraterone acetate plus prednisone for 24 weeks prior to prostatectomy. Germline DNA was genotyped for 13 SNPs in six SLCO genes.Results: Abiraterone levels spanned a broad range (serum median 28 ng/mL, 108 nmol/L; tissue median 77 ng/mL, 271 nmol/L) and were correlated (r = 0.355, P = 0.001). Levels correlated positively with steroids upstream of CYP17A (pregnenolone, progesterone), and inversely with steroids downstream of CYP17A (DHEA, AED, testosterone). Serum PSA and tumor volumes were higher in men with undetectable versus detectable tissue abiraterone at prostatectomy (median 0.10 vs. 0.03 ng/dL, P = 0.02; 1.28 vs. 0.44 cc, P = 0.09, respectively). SNPs in SLCO2B1 associated with significant differences in tissue abiraterone (rs1789693, P = 0.0008; rs12422149, P = 0.03) and higher rates of minimal residual disease (tumor volume < 0.5 cc; rs1789693, 67% vs. 27%, P = 0.009; rs1077858, 46% vs. 0%, P = 0.03). LNCaP cells expressing SLCO2B1 showed two- to fourfold higher abiraterone levels compared with vector controls (P < 0.05).Conclusions: Intraprostatic abiraterone levels and genetic variation in SLCO genes are associated with pathologic responses in high-risk localized prostate cancer. Variation in SLCO genes may serve as predictors of response to abiraterone treatment. Clin Cancer Res; 23(16); 4592-601. ©2017 AACR.

External beam radiation therapy and abiraterone in men with localized prostate cancer: safety and effect on tissue androgens

PURPOSE

Optimizing androgen suppression may provide better control of localized prostate cancer (PCa). Numerous trials have supported the benefit of combining androgen deprivation therapy with definitive radiation therapy in men with locally advanced or high-grade disease. Addition of abiraterone to luteinizing hormone-releasing hormone agonist (LHRHa) with radiation has not been reported. We examined the safety of this combination as well as its impact on androgen suppression.

METHODS AND MATERIALS

A prospective, phase 2 study was conducted in men with localized PCa treated with 6 months of neoadjuvant and concurrent abiraterone with LHRHa and radiation. Duration of adjuvant LHRHa was at the discretion of the treating clinician. Prostate biopsy assays were obtained prior to the start of therapy and prior to radiation. Sera and tissue androgen levels were measured by liquid chromatography-tandem mass spectrometry.

RESULTS

A total of 22 men with intermediate- (n=3) and high-risk PCa (n=19) received study therapy. Sixteen men completed the intended course of abiraterone, and 19 men completed planned radiation to 77.4 to 81 Gy. Radiation to pelvic nodes was administered in 20 men. The following grade 3 toxicities were reported: lymphopenia (14 patients), fatigue (1 patient), transaminitis (2 patients), hypertension (2 patients), and hypokalemia (1 patient). There were no grade 4 toxicities. All 21 men who complied with at least 3 months of abiraterone therapy had a preradiation prostate-specific antigen (PSA) concentration nadir of <0.3 ng/mL. Median levels of tissue androgen downstream of CYP17A were significantly suppressed after treatment with abiraterone, and upstream steroids were increased. At median follow-up of 21 months (range: 3-37 months), only 1 patient (who had discontinued abiraterone at 3 months) had biochemical relapse.

CONCLUSIONS

Addition of abiraterone to LHRHa with radiation is safe and achieves effective prostatic androgen suppression. Preliminary analysis of the clinical data is also promising, with excellent PSA nadir and no relapse to date in this high-risk population.

Activity of enzalutamide in men with metastatic castration-resistant prostate cancer is affected by prior treatment with abiraterone and/or docetaxel

BACKGROUND

Enzalutamide and abiraterone are new androgen-axis disrupting treatments for metastatic castration resistant prostate cancer (mCRPC). We examined response and outcomes of enzalutamide-treated mCRPC patients in the real-world context of prior treatments of abiraterone and/or docetaxel.

METHODS

We conducted a seven-institution retrospective study of mCRPC patients treated with enzalutamide between January 2009 and February 2014. We compared baseline characteristics, PSA declines, PSA progression-free survival (PSA-PFS), duration on enzalutamide, and overall survival (OS) across subgroups defined by prior abiraterone and/or docetaxel.

RESULTS

Of 310 patients who received enzalutamide, 36 (12%) received neither prior abiraterone nor prior docetaxel, 79 (25%) received prior abiraterone, 30 (10%) received prior docetaxel, and 165 (53%) received both prior abiraterone and prior docetaxel. Within these groups, respectively, ≥30% PSA decline was achieved among 67%, 28%, 43%, and 24% of patients; PSA-PFS was 5.5 (95% CI 4.2–9.1), 4.0 (3.2–4.8), 4.1 (2.9–5.4), and 2.8 (2.5–3.2) months; median duration of enzalutamide was 9.1 (7.3-not reached), 4.7 (3.7–7.7), 5.4 (3.8–8.4), and 3.9 (3.0–4.6) months. Median OS was reached only for patients who received both prior abiraterone and docetaxel and was 12.2 months (95% CI 10.7–16.5). 12-month OS was 78% (59%–100%), 64% (45%–90%), 77% (61%–97%), and 51% (41%–62%). Of 70 patients who failed to achieve any PSA decline on prior abiraterone, 19 (27%) achieved ≥30% PSA decline with subsequent enzalutamide.

CONCLUSIONS

The activity of enzalutamide is blunted after abiraterone, after docetaxel, and still more after both, suggesting subsets of overlapping and distinct mechanisms of resistance.

Minireview: SLCO and ABC transporters: a role for steroid transport in prostate cancer progression

Androgens play a critical role in the development and progression of prostate cancer (PCa), and androgen deprivation therapy via surgical or medical castration is front-line therapy for patients with advanced PCa. However, intratumoral testosterone levels are elevated in metastases from patients with castration-resistant disease, and residual intratumoral androgens have been implicated in mediating ligand-dependent mechanisms of androgen receptor activation. The source of residual tissue androgens present despite castration has not been fully elucidated, but proposed mechanisms include uptake and conversion of adrenal androgens, such as dehdroepiandrosterone to testosterone and dihydrotestosterone, or de novo androgen synthesis from cholesterol or progesterone precursors. In this minireview, we discuss the emerging evidence that suggests a role for specific transporters in mediating transport of steroids into or out of prostate cells, thereby influencing intratumoral androgen levels and PCa development and progression. We focus on the solute carrier and ATP binding cassette gene families, which have the most published data for a role in PCa-related steroid transport, and review the potential impact of genetic variation on steroid transport activity and PCa outcomes. Continued assessment of transport activity in PCa models and human tumor tissue is needed to better delineate the different roles these transporters play in physiologic and neoplastic settings, and in order to determine whether targeting the uptake of steroid substrates by specific transporters may be a clinically feasible therapeutic strategy.

Prostate cancer characteristics associated with response to pre-receptor targeting of the androgen axis

BACKGROUND

Factors influencing differential responses of prostate tumors to androgen receptor (AR) axis-directed therapeutics are poorly understood, and predictors of treatment efficacy are needed. We hypothesized that the efficacy of inhibiting DHT ligand synthesis would associate with intra-tumoral androgen ratios indicative of relative dependence on DHT-mediated growth.

METHODS

We characterized two androgen-sensitive prostate cancer xenograft models after androgen suppression by castration in combination with the SRD5A inhibitor, dutasteride, as well as a panel of castration resistant metastases obtained via rapid autopsy.

RESULTS

In LuCaP35 tumors (intra-tumoral T:DHT ratio 2:1) dutasteride suppressed DHT to 0.02 ng/gm and prolonged survival vs. castration alone (337 vs.152 days, HR 2.8, p = 0.0015). In LuCaP96 tumors (T:DHT 10:1), survival was not improved despite similar DHT reduction (0.02 ng/gm). LuCaP35 demonstrated higher expression of steroid biosynthetic enzymes maintaining DHT levels (5-fold higher SRD5A1, 41 fold higher, 99-fold higher RL-HSD, p<0.0001 for both), reconstitution of intra-tumoral DHT (to ∼30% of untreated tumors), and ∼2 fold increased expression of full length AR. In contrast, LuCaP96 demonstrated higher levels of steroid catabolizing enzymes (6.9-fold higher AKR1C2, 3000-fold higher UGT2B15, p = 0.002 and p<0.0001 respectively), persistent suppression of intra-tumoral DHT, and 6-8 fold induction of full length AR and the ligand independent V7 AR splice variant. Human metastases demonstrated bio-active androgen levels and AR full length and AR splice-variant expression consistent with the range observed in xenografts.

CONCLUSIONS

Intrinsic differences in basal steroidogenesis, as well as variable expression of full length and splice-variant AR, associate with response and resistance to pre-receptor AR ligand suppression. Expression of steroidogenic enzymes and AR isoforms may serve as potential biomarkers of sensitivity to potent AR-axis inhibition and should be validated in additional models.

Impact of circulating cholesterol levels on growth and intratumoral androgen concentration of prostate tumors

Prostate cancer (PCa) is the second most common cancer in men. Androgen deprivation therapy (ADT) leads to tumor involution and reduction of tumor burden. However, tumors eventually reemerge that have overcome the absence of gonadal androgens, termed castration resistant PCa (CRPC). Theories underlying the development of CRPC include androgen receptor (AR) mutation allowing for promiscuous activation by non-androgens, AR amplification and overexpression leading to hypersensitivity to low androgen levels, and/or tumoral uptake and conversion of adrenally derived androgens. More recently it has been proposed that prostate tumor cells synthesize their own androgens through de novo steroidogenesis, which involves the step-wise synthesis of androgens from cholesterol. Using the in vivo LNCaP PCa xenograft model, previous data from our group demonstrated that a hypercholesterolemia diet potentiates prostatic tumor growth via induction of angiogenesis. Using this same model we now demonstrate that circulating cholesterol levels are significantly associated with tumor size (R = 0.3957, p = 0.0049) and intratumoral levels of testosterone (R = 0.41, p = 0.0023) in LNCaP tumors grown in hormonally intact mice. We demonstrate tumoral expression of cholesterol uptake genes as well as the spectrum of steroidogenic enzymes necessary for androgen biosynthesis from cholesterol. Moreover, we show that circulating cholesterol levels are directly correlated with tumoral expression of CYP17A, the critical enzyme required for de novo synthesis of androgens from cholesterol (R = 0.4073, p = 0.025) Since hypercholesterolemia does not raise circulating androgen levels and the adrenal gland of the mouse synthesizes minimal androgens, this study provides evidence that hypercholesterolemia increases intratumoral de novo steroidogenesis. Our results are consistent with the hypothesis that cholesterol-fueled intratumoral androgen synthesis may accelerate the growth of prostate tumors, and suggest that treatment of CRPC may be optimized by inclusion of cholesterol reduction therapies in conjunction with therapies targeting androgen synthesis and the AR.

Resistance to CYP17A1 inhibition with abiraterone in castration-resistant prostate cancer: induction of steroidogenesis and androgen receptor splice variants

PURPOSE

Abiraterone is a potent inhibitor of the steroidogenic enzyme CYP17A1 and suppresses tumor growth in patients with castration-resistant prostate cancer (CRPC). The effectiveness of abiraterone in reducing tumor androgens is not known, nor have mechanisms contributing to abiraterone resistance been established.

EXPERIMENTAL DESIGN

We treated human CRPC xenografts with abiraterone and measured tumor growth, tissue androgens, androgen receptor (AR) levels, and steroidogenic gene expression versus controls.

RESULTS

Abiraterone suppressed serum PSA levels and improved survival in two distinct CRPC xenografts: median survival of LuCaP35CR improved from 17 to 39 days (HR = 3.6, P = 0.0014) and LuCaP23CR from 14 to 24 days (HR = 2.5, P = 0.0048). Abiraterone strongly suppressed tumor androgens, with testosterone (T) decreasing from 0.49 ± 0.22 to 0.03 ± 0.01 pg/mg (P < 0.0001), and from 0.69 ± 0.36 to 0.03 ± 0.01 pg/mg (P = 0.002) in abiraterone-treated 23CR and 35CR, respectively, with comparable decreases in tissue DHT. Treatment was associated with increased expression of full-length AR (AR(FL)) and truncated AR variants (AR(FL) 2.3-fold, P = 0.008 and AR(del567es) 2.7-fold, P = 0.036 in 23 CR; AR(FL) 3.4-fold, P = 0.001 and AR(V7) 3.1-fold, P = 0.0003 in 35CR), and increased expression of the abiraterone target CYP17A1 (∼2.1-fold, P = 0.0001 and P = 0.028 in 23CR and 35CR, respectively) and transcript changes in other enzymes modulating steroid metabolism.

CONCLUSIONS

These studies indicate that abiraterone reduces CRPC growth via suppression of intratumoral androgens and that resistance to abiraterone may occur through mechanisms that include upregulation of CYP17A1, and/or induction of AR and AR splice variants that confer ligand-independent AR transactivation.

Expression of SLCO transport genes in castration-resistant prostate cancer and impact of genetic variation in SLCO1B3 and SLCO2B1 on prostate cancer outcomes

BACKGROUND

Metastases from men with castration-resistant prostate cancer (CRPC) harbor increased tumoral androgens versus untreated prostate cancers. This may reflect steroid uptake by OATP (organic anion transporting polypeptide)/SLCO transporters. We evaluated SLCO gene expression in CRPC metastases and determined whether prostate cancer outcomes are associated with single nucleotide polymorphisms (SNP) in SLCO2B1 and SLCO1B3, transporters previously shown to mediate androgen uptake.

METHODS

Transcripts encoding eleven SLCO genes were analyzed in untreated prostate cancer and in metastatic CRPC tumors obtained by rapid autopsy. SNPs in SLCO2B1 and SLCO1B3 were genotyped in a population-based cohort of 1,309 Caucasian prostate cancer patients. Median survival follow-up was 7.0 years (0.77-16.4). The risk of prostate cancer recurrence/progression and prostate cancer-specific mortality (PCSM) was estimated with Cox proportional hazards analysis.

RESULTS

Six SLCO genes were highly expressed in CRPC metastases versus untreated prostate cancer, including SLCO1B3 (3.6-fold; P = 0.0517) and SLCO2B1 (5.5-fold; P = 0.0034). Carriers of the variant alleles SLCO2B1 SNP rs12422149 (HR: 1.99; 95% CI: 1.11-3.55) or SLCO1B3 SNP rs4149117 (HR: 1.76; 95% CI: 1.00-3.08) had an increased risk of PCSM.

CONCLUSIONS

CRPC metastases show increased expression of SLCO genes versus primary prostate cancer. Genetic variants of SLCO1B3 and SLCO2B1 are associated with PCSM. Expression and genetic variation of SLCO genes which alter androgen uptake may be important in prostate cancer outcomes.

IMPACT

OATP/SLCO genes may be potential biomarkers for assessing risk of PCSM. Expression and genetic variation in these genes may allow stratification of patients to more aggressive hormonal therapy or earlier incorporation of nonhormonal-based treatment strategies.

Conditioning of a free operant in Octupus cyaneus Gray

Operant conditioning was studied in six specimens of Octopus cyaneus Gray. An "arm-out-of-water" operant, in which the octopus inserted an arm up a feeding-tube breaking the water surface, proved susceptible to reinforcement schedules. An apparatus was developed that provided automated reinforcement and recording. Performance was studied under continuous reinforcement, fixed-ratio and variable-ratio schedules, and extinction conditions.

Reduced tumor necrosis factor receptor-associated death domain expression is associated with prostate cancer progression

By using LNCaP and its derivative cell lines, we first observed an association between tumor necrosis factor-alpha (TNF-alpha) resistance and hormone independence. Moreover, we found that the expression of tumor necrosis factor receptor-associated death domain (TRADD) was reduced in androgen deprivation-independent cells compared with that in androgen deprivation-dependent cells. TRADD is a crucial transducer for TNF-alpha-induced nuclear factor-kappaB (NF-kappaB) activation. Knocking down TRADD expression in LNCaP cells impaired TNF-alpha-induced NF-kappaB activation and androgen receptor repression, whereas overexpression of TRADD in C4-2B cells restored their sensitivity to TNF-alpha. Finally, we found that androgen deprivation reduces TRADD expression in vitro and in vivo, suggesting that androgen deprivation therapy may promote the development of TNF-alpha resistance by reducing TRADD expression during prostate cancer progression.

MEK4 function, genistein treatment, and invasion of human prostate cancer cells

BACKGROUND

Dietary intake of genistein by patients with prostate cancer has been associated with decreased metastasis and mortality. Genistein blocks activation of p38 mitogen-activated protein kinase and thus inhibits matrix metalloproteinase-2 (MMP-2) expression and cell invasion in cultured cells and inhibits metastasis of human prostate cancer cells in mice. We investigated the target for genistein in prostate cancer cells.

METHODS

Prostate cell lines PC3-M, PC3, 1532NPTX, 1542NPTX, 1532CPTX, and 1542CPTX were used. All cell lines were transiently transfected with a constitutively active mitogen-activated protein kinase kinase 4 (MEK4) expression vector (to increase MEK4 expression), small interfering RNA against MEK4 (to decrease MEK4 expression), or corresponding control constructs. Cell invasion was assessed by a Boyden chamber assay. Gene expression was assessed by a quantitative reverse transcription-polymerase chain reaction. Protein expression was assessed by Western blot analysis. Modeller and AutoDock programs were used for modeling of the structure of MEK4 protein and ligand docking, respectively. MMP-2 transcript levels were assessed in normal prostate epithelial cells from 24 patients with prostate cancer from a phase II randomized trial comparing genistein treatment with no treatment. Statistical significance required a P value of .050 or less. All statistical tests were two-sided.

RESULTS

Overexpression of MEK4 increased MMP-2 expression and cell invasion in all six cell lines. Decreased MEK4 expression had the opposite effects. Modeling showed that genistein bound to the active site of MEK4. Genistein inhibited MEK4 kinase activity with a half maximal inhibitory concentration of 0.40 microM (95% confidence interval [CI] = 0.36 to 0.45 muM). The MMP-2 transcript level in normal prostate epithelial cells was statistically significantly higher in the untreated group (100%) than in the genistein-treated group (24%; difference = 76%, 95% CI = 38% to 115%; P = .045).

CONCLUSIONS

We identified MEK4 as a proinvasion protein in six human prostate cancer cell lines and the target for genistein. We showed, to our knowledge for the first time, that genistein treatment, compared with no treatment, was associated with decreased levels of MMP-2 transcripts in normal prostate cells from prostate cancer-containing tissue.

Circulating tumor cells predict survival benefit from treatment in metastatic castration-resistant prostate cancer

PURPOSE

A method for enumerating circulating tumor cells (CTC) has received regulatory clearance. The primary objective of this prospective study was to establish the relationship between posttreatment CTC count and overall survival (OS) in castration-resistant prostate cancer (CRPC). Secondary objectives included determining the prognostic utility of CTC measurement before initiating therapy, and the relationship of CTC to prostate-specific antigen (PSA) changes and OS at these and other time points.

EXPERIMENTAL DESIGN

Blood was drawn from CRPC patients with progressive disease starting a new line of chemotherapy before treatment and monthly thereafter. Patients were stratified into predetermined Favorable or Unfavorable groups (<5 and > or =5 CTC/7.5mL).

RESULTS

Two hundred thirty-one of 276 enrolled patients (84%) were evaluable. Patients with Unfavorable pretreatment CTC (57%) had shorter OS (median OS, 11.5 versus 21.7 months; Cox hazard ratio, 3.3; P < 0.0001). Unfavorable posttreatment CTC counts also predicted shorter OS at 2 to 5, 6 to 8, 9 to 12, and 13 to 20 weeks (median OS, 6.7-9.5 versus 19.6-20.7 months; Cox hazard ratio, 3.6-6.5; P < 0.0001). CTC counts predicted OS better than PSA decrement algorithms at all time points; area under the receiver operator curve for CTC was 81% to 87% and 58% to 68% for 30% PSA reduction (P = 0.0218). Prognosis for patients with (a) Unfavorable baseline CTC who converted to Favorable CTC improved (6.8 to 21.3 months); (b) Favorable baseline CTC who converted to Unfavorable worsened (>26 to 9.3 months).

CONCLUSIONS

CTC are the most accurate and independent predictor of OS in CRPC. These data led to Food and Drug Administration clearance of this assay for the evaluation of CRPC.

Maintenance of intratumoral androgens in metastatic prostate cancer: a mechanism for castration-resistant tumor growth

Therapy for advanced prostate cancer centers on suppressing systemic androgens and blocking activation of the androgen receptor (AR). Despite anorchid serum androgen levels, nearly all patients develop castration-resistant disease. We hypothesized that ongoing steroidogenesis within prostate tumors and the maintenance of intratumoral androgens may contribute to castration-resistant growth. Using mass spectrometry and quantitative reverse transcription-PCR, we evaluated androgen levels and transcripts encoding steroidogenic enzymes in benign prostate tissue, untreated primary prostate cancer, metastases from patients with castration-resistant prostate cancer, and xenografts derived from castration-resistant metastases. Testosterone levels within metastases from anorchid men [0.74 ng/g; 95% confidence interval (95% CI), 0.59-0.89] were significantly higher than levels within primary prostate cancers from untreated eugonadal men (0.23 ng/g; 95% CI, 0.03-0.44; P < 0.0001). Compared with primary prostate tumors, castration-resistant metastases displayed alterations in genes encoding steroidogenic enzymes, including up-regulated expression of FASN, CYP17A1, HSD3B1, HSD17B3, CYP19A1, and UGT2B17 and down-regulated expression of SRD5A2 (P < 0.001 for all). Prostate cancer xenografts derived from castration-resistant tumors maintained similar intratumoral androgen levels when passaged in castrate compared with eugonadal animals. Metastatic prostate cancers from anorchid men express transcripts encoding androgen-synthesizing enzymes and maintain intratumoral androgens at concentrations capable of activating AR target genes and maintaining tumor cell survival. We conclude that intracrine steroidogenesis may permit tumors to circumvent low levels of circulating androgens. Maximal therapeutic efficacy in the treatment of castration-resistant prostate cancer will require novel agents capable of inhibiting intracrine steroidogenic pathways within the prostate tumor microenvironment.

Association of Body Mass Index With Response and Survival in Men With Metastatic Prostate Cancer: Southwest Oncology Group Trials 8894 and 9916

PURPOSE

We evaluated the effect of body mass index on prostate specific antigen response, and progression-free and overall survival in men with androgen dependent or androgen independent metastatic prostate cancer.

MATERIALS AND METHODS

We examined the prognostic impact of body mass index in patient cohorts from phase III randomized studies coordinated by the Southwest Oncology Group. The first study included 1,006 men treated with androgen deprivation for metastatic prostate cancer. The second study included 671 patients treated with chemotherapy for metastatic, androgen independent prostate cancer.

RESULTS

Among men with androgen dependent disease, higher body mass index was associated with longer overall (p <0.001) and progression-free (p = 0.009) survival, as well as with an increased likelihood of achieving a prostate specific antigen nadir less than 4 ng/ml (p = 0.008). In multivariate analysis adjusting for risk factors, increasing body mass index was positively correlated with overall survival (p <0.01) and overweight but not obese patients (body mass index 27 to 29.9) had a significantly improved outcome compared to normal weight patients, with hazard ratios for risk of progression and death of 0.82 (95% CI 0.69, 0.98) and 0.75 (95% CI 0.63, 0.89), respectively. Among men with androgen independent prostate cancer, no clear association could be detected between body mass index and progression-free survival, overall survival or prostate specific antigen response.

CONCLUSIONS

This study revealed higher body mass index to be associated with better overall and progression-free survival in patients with androgen dependent metastatic prostate cancer. Among men who had androgen independent disease, no significant association was found between body mass index and survival.

Do Statins Affect Androgen Levels in Men? Results from the Boston Area Community Health Survey

BACKGROUND

In 2005, statins were among the most commonly used prescription medications in the United States. Some data suggest statins may affect cancer risk and/or disease severity. Because cholesterol is a required intermediate in sex steroid synthesis, it is possible that statins influence prostate cancer risk through effects on steroid hormone metabolism. We investigated whether levels of circulating androgens and their carrier protein, sex hormone-binding globulin (SHBG), varied by statin exposure among a sample of 1,812 men from a population-based epidemiologic study, the Boston Area Community Health Survey.

METHODS

We measured serum total testosterone, free testosterone, dehydroepiandrosterone sulfate, luteinizing hormone, and SHBG. Statin exposure was collected through participant self-report and/or interviewer-recorded information. Multivariate linear models were constructed to account for potential confounding.

RESULTS

The prevalence of statin use was 12.4% [95% confidence interval (95% CI), 10.3-14.9]. On average, statin users were older, had larger body mass index and more chronic illnesses, and used more medications. We found no relationship between statin use and free testosterone, dehydroepiandrosterone sulfate, or luteinizing hormone. A significant association between statin use and total testosterone was initially observed but was not robust to covariate control in a multivariate model that included age, body mass index, time since awakening, and history of cardiovascular disease and diabetes (-5.5%; 95% CI, -13.2 to 2.9%). In multivariate models adjusted similarly, SHBG levels among statin users were statistically significantly lower compared with nonusers (-10.6%; 95% CI, -18.8 to -1.6%).

CONCLUSION

In this sample, it is unlikely that statins affect circulating androgens and prostate cancer risk through a hormonal mechanism.

Diethylstilbestrol and docetaxel

BACKGROUND

The addition of diethylstilbestrol to docetaxel modified tubulin composition and improved the response of prostate cancer to chemotherapy in preclinical models. An attempt was made to recapitulate the observations in a clinical trial.

METHODS

Twenty-nine patients with progressive, metastatic, chemotherapy-naive androgen-independent prostate cancer were treated with diethylstilbestrol 1 mg daily and 5 mg on the day before docetaxel and docetaxel 36 mg/m(2) intravenously weekly for 3 weeks of a 4-week cycle. Prophylactic anticoagulation was used in all patients. Patients were assessed by prostate-specific antigen (PSA) monthly and computed tomography (CT) and bone scans every 3 cycles. The Response Evaluation Criteria in Solid Tumors (RECIST) criteria and PSA decline by >50% maintained for 4 weeks were used to assess activity.

RESULTS

The median age was 68 years (range, 56-84 years), Southwest Oncology Group performance status 0 (score range, 0-2), alkaline phosphatase 120 U/L (range, 49-523), hemoglobin (Hgb) 12.6 g/dL (range, 9.2-16.3), PSA 66 ng/dL (range, 4-1962). The median number of cycles administered was 6. Soft tissue metastases were present in 51% of patients and bone metastases in 93%. Twenty-nine patients are evaluable for response. Of these, 20 patients (69%, 95% confidence interval [CI], 49%-85%) had a PSA decline of >50% and the PSA declined by >90% in 12 patients (41%, 95% CI, 23.1%-58.9%). Of 15 patients with measurable disease, 6 (40%, 95% CI, 23.5%-61%) had a partial response. Median time to progression was 6 months (range, 3-19 months). Fifteen patients (51%) suffered grade 3/4 toxicity. Two patients died of causes unrelated to therapy and another died from a steroid-induced ulcer. Six patients developed thrombosis and of those tested 75% had Factor V mutations. Pretreatment PSA, performance status, Hgb, and alkaline phosphatase had no impact on the likelihood of response.

CONCLUSIONS

The combination of diethylstilbestrol and docetaxel produces a significant level of activity, measured by PSA decline and measurable disease response rate, and except for venous thrombosis the toxicity appears similar to that seen with docetaxel plus prednisone. These results suggest that tubulin modulation with diethylstilbestrol may improve the therapeutic efficacy of docetaxel and the combination is worthy of further study.

Combined In vivo Effect of A12, a Type 1 Insulin-Like Growth Factor Receptor Antibody, and Docetaxel against Prostate Cancer Tumors

PURPOSE

A human type 1 insulin-like growth factor receptor antibody (A12) has been shown to effectively inhibit human xenograft tumor growth, including androgen-dependent and androgen-independent prostate tumors. Docetaxel, either as a single agent or combined with others, has shown a survival benefit in prostate cancer patients. Based on these data, we investigated the combined in vivo effect of A12 and docetaxel on human androgen-independent and osseous prostate tumor growth.

EXPERIMENTAL DESIGN

To study human androgen-independent prostate cancer model, LuCaP35V tumors were implanted s.c. into castrated severe combined immunodeficient mice. When tumors reached about 100 mm3, animals were treated with vehicle control docetaxel (10 or 20 mg/kg) and docetaxel in combination with A12 (40 microg/kg) for 4 weeks. To study human osseous prostate cancer model, LuCaP 23.1 tumors were implanted intratibiae. When serum prostate-specific antigen reached 5 to 10 ng/mL, treatments were initiated.

RESULTS

A12 markedly augmented the inhibition of docetaxel on tumor growth. When docetaxel is combined with A12, the inhibition of tumor growth continued after treatment cessation, which was associated with continued apoptosis and decreased proliferation of tumor cells. Gene expression profiles indicated that the posttreatment suppression of tumor growth may be due to enhanced negative regulation of cell cycle progression- and/or cell survival-associated genes, some of which have been shown to induce resistance to docetaxel.

CONCLUSIONS

Our findings suggest that targeting type 1 insulin-like growth factor receptor can enhance the therapeutic effect of docetaxel on advanced prostate cancer. Our findings also suggest a potential mechanism to improve the treatment efficacy of docetaxel in prostate cancer.

Tumor lysis syndrome in a patient with metastatic, androgen independent prostate cancer

Tumor lysis syndrome (TLS) is an uncommon, but well described, clinical entity that typically occurs following chemotherapy in patients with rapidly growing hematological malignancies. It is rarely described in patients with solid tumors. We report a case of TLS in a patient with metastatic adenocarcinoma of the prostate after treatment with paclitaxel chemotherapy.

Estrogen effects on tubulin expression and taxane mediated cytotoxicity in prostate cancer cells

BACKGROUND

The present study was designed to determine if estrogens change microtubule polymerization and modulate cell cycle progression in vitro, related to modulation of tubulin expression and to determine if estrogens had antagonistic or synergistic effects with microtubule active agents.

METHODS

cDNA array analysis of LNCaP cells treated with the estrogens, estradiol, estrone, diethylstilbestrol (DES), and 2-methoxyestradiol (2-ME) was carried out and the results confirmed by PCR and Western blotting. Microtubule arrays in cells treated with estrogens were assessed using indirect immunofluorescence. The effects of combining estrogens with taxane was assessed by MTT assay and flow cytometry for cell cycle kinetics. Human prostate cancer xenografts were treated with DES and docetaxel to assess the effects of combining estrogens and taxane in vivo.

RESULTS

Treatment of LNCaP cells with DES and 2-ME suppressed transcripts and protein for beta-tubulin isotype IVa. This effect on tubulin synthesis was not blocked by estrogen or androgen receptor modulators. Other estrogens had no effect on beta-tubulin expression. 2-ME and DES decreased the density of microtubules. The administration of DES or 2-ME with paclitaxel enhanced cytotoxicity and G(2)-M arrest in vitro. DES enhanced tumor suppression in a human prostate cancer xenograft model when combined with the taxane docetaxel.

CONCLUSION

The use of DES and 2-ME enhances the effects of taxanes and may be a novel and important means of increasing therapeutic efficacy of cytotoxic chemotherapy against prostate carcinoma.

Phase I and initial phase II results from a trial investigating weekly docetaxel and carboplatin given neoadjuvantly and then concurrently with concomitant boost radiotherapy for locally advanced squamous cell carcinoma of the head and neck

BACKGROUND

The current Phase I/II study assessed induction docetaxel/carboplatin given weekly for 4 weeks, followed by weekly docetaxel/carboplatin and concomitant boost radiotherapy (CB-XRT) for locally advanced head and neck squamous cell carcinoma.

METHODS

Twenty patients with Stage III or IV (M0) disease of the oropharynx, supraglottic larynx, or hypopharynx were enrolled. Patients initially received docetaxel 20 mg/m2 and carboplatin area under the curve (AUC) 2 weekly x 4. Patients with stable (SD) or responding disease subsequently received dose-escalated docetaxel (10-20 mg/m2 in sequential patient cohorts) and carboplatin AUC 1 weekly x 5 with CB-XRT (1.8 gray [Gy] every day x 15 days, followed by 1.8/1.5 Gy twice per day x 13 days).

RESULTS

All patients were evaluable, and 15 patients (5 patients with Stage III disease, 10 patients with Stage IV disease) completed all planned therapy. The target docetaxel dose level of 20 mg/m(2) weekly with radiotherapy was achieved with no dose-limiting toxicities. The most frequent maximum toxicities during chemoradiotherapy were Grade 3 mucositis, dysphagia, and/or pain. Primary site responses after induction included 4 patients with partial responses, 11 patients with SD, and 5 patients with disease progression. Fifteen patients (75%) continued to receive chemoradiotherapy, with 14 patients attaining a complete response (CR). Overall, a clinicopathologic neck CR after chemoradiotherapy was achieved in 9 of 10 patients. One patient had persistent primary disease and underwent salvage surgery, whereas another died of unrelated causes before neck assessment. Thirteen patients remain free of any disease event, with a median follow-up of 15 months (range, 3-29 months).

CONCLUSIONS

This regimen was feasible, safe, and particularly well tolerated. Early Phase II outcomes revealed promising activity in patients completing all treatment. Initial induction response results suggested that further investigation of this regimen with more aggressive induction therapy is warranted.

Endogenous anti-HER2 antibodies block HER2 phosphorylation and signaling through extracellular signal-regulated kinase

Immunologic targeting of the oncoprotein HER2/neu with monoclonal antibodies is an important component of current therapeutic strategies for patients with locally and systemically advanced breast cancer. Engineered antibodies targeting HER2 may have agonist or antagonist effects on HER2, but little is known about whether endogenous antibodies modulate HER2 activity. Vaccination of patients with HER2 peptides successfully induced antibodies in a minority of patients with HER2-expressing malignancy. A subset of antibodies specifically suppressed phosphorylation of HER2 on tyrosine Y1248, a residue critical for HER2 signaling through extracellular signal-regulated kinase. These antibodies also suppressed extracellular signal-regulated kinase phosphorylation and inhibited colony formation in soft agar. The majority of the antibodies that suppressed HER2 phosphorylation displayed specificity for amino acids 328 to 345 and 369 to 384. The isotype of anti-HER2 antibodies was predominantly IgG3 of low avidity, suggesting a Th1 response to peptide vaccine. Endogenous anti-HER2 antibodies can effectively suppress HER2 kinase activity and downstream signaling to inhibit the transformed phenotype of HER2-expressing tumor cells.

Endogenous Anti-HER2 Antibodies Block HER2 Phosphorylation and Signaling through Extracellular Signal-Regulated Kinase

Immunologic targeting of the oncoprotein HER2/neu with monoclonal antibodies is an important component of current therapeutic strategies for patients with locally and systemically advanced breast cancer. Engineered antibodies targeting HER2 may have agonist or antagonist effects on HER2, but little is known about whether endogenous antibodies modulate HER2 activity. Vaccination of patients with HER2 peptides successfully induced antibodies in a minority of patients with HER2-expressing malignancy. A subset of antibodies specifically suppressed phosphorylation of HER2 on tyrosine Y1248, a residue critical for HER2 signaling through extracellular signal-regulated kinase. These antibodies also suppressed extracellular signal-regulated kinase phosphorylation and inhibited colony formation in soft agar. The majority of the antibodies that suppressed HER2 phosphorylation displayed specificity for amino acids 328 to 345 and 369 to 384. The isotype of anti-HER2 antibodies was predominantly IgG3 of low avidity, suggesting a Th1 response to peptide vaccine. Endogenous anti-HER2 antibodies can effectively suppress HER2 kinase activity and downstream signaling to inhibit the transformed phenotype of HER2-expressing tumor cells.

Antagonistic and agonistic effects of quinazoline tyrosine kinase inhibitors on mutant EGF receptor function

A mutated form of the EGF receptor (EGFRvIII), resulting from deletion of exons 2-7, is an oncogenic protein that is expressed in multiple human tumors. This mutation induces ligand-independent activation of the EGFR tyrosine kinase and thereby can initiate unregulated cell growth and tumorigenesis. Thus, inhibition of the kinase activity of EGFRvIII is a potential means of suppressing its oncogenic properties. Certain tyrosine kinase inhibitors (tyrphostins) specifically inhibit the wild-type EGFR and thereby inhibit tumor growth both in vitro and in vivo. We demonstrate that the quinazoline tyrphostins AG 1478 and AG 1517 can suppress morphologic transformation of cell lines by EGFRvIII. Quinazolines were found to inhibit receptor autophosphorylation and signaling through MAP kinase, but had minimal effects on association of EGFRvIII with Grb2/SOS. Low concentrations of quinazoline also increased receptor dimerization and phosphotyrosine content. This was associated with increases in colony formation in soft agar and increased invasion through matrigel for AG 1478. Thus, both AG 1478 and AG 1517 can inhibit multiple EGFRvIII signaling pathways, but at low concentrations AG 1478 can enhance colony formation, presumably related to augmented homodimerization of the receptor and activation of downstream signaling.

The development of a telemedical cancer center within the Veterans Affairs Health Care System: a report of preliminary clinical results

In order to optimize the delivery of multidisciplinary cancer care to veterans, our institution has developed a regional cancer center with a telemedical outreach program. The objectives of this report are to describe the organization and function of the telemedical cancer center and to report our early clinical results. The Veterans Affairs Health Care System is organized into a series of integrated service networks that serve veterans within different areas throughout the United States. Within Veterans Integrated Service Network 20 (Washington, Alaska, Idaho, Oregon) we have developed a regional cancer center with telemedicine links to four outlying facilities within the service area. The telemedical outreach effort functions through the use of a multidisciplinary telemedicine tumor board. The tumor board serves patients in outlying facilities by providing comprehensive, multidisciplinary consultation for the complete range of malignancies. For individuals who do require referral to the cancer center, the tumor board serves to coordinate the logistical and clinical details of the referral process. This program has been in existence for 1 year. During that time 85 patients have been evaluated in the telemedicine tumor board. Sixty-two percent of the patients were treated at their closest facility; 38% were referred to the cancer center for treatment and/or additional diagnostic studies. The patients' diagnoses included the entire clinical spectrum of malignant disease. Preliminary clinical results demonstrate the program is feasible and it improves access to multidisciplinary cancer care. Potential benefits include improved referral coordination and minimization of patient travel and treatment delays.

Expression of oncogenic epidermal growth factor receptor family kinases induces paclitaxel resistance and alters beta-tubulin isotype expression

Oncogenic transformation confers resistance to chemotherapy through a variety of mechanisms, including suppression of apoptosis, increased drug metabolism, and modification of target proteins. Oncogenic epidermal growth factor receptor family members, including EGFRvIII and HER2, are expressed in a broad spectrum of human malignancies. Cell lines transfected with EGFRvIII and HER2 are more resistant to paclitaxel-mediated cytotoxicity, and tubulin polymerization induced by paclitaxel is suppressed compared with cells expressing wild type epidermal growth factor receptor. Because differential expression of beta-tubulin isotypes has been proposed to modulate paclitaxel resistance, we analyzed beta-tubulin isotypes expressed in cell lines transfected with different oncogenes. EGFRvIII- and HER2-expressing cells demonstrated equivalent total beta-tubulin protein compared with cells transfected with wild type receptor or untransfected controls. EGFRvIII-expressing cells demonstrated increases in class IVa (2.5-fold) and IVb (3.1-fold) mRNA, and HER2-expressing cells showed increases in class IVa (2. 95-fold) mRNA. Expression of oncogenic Ha-Ras did not change class IV RNA levels significantly. Inhibition of EGFRvIII kinase activity using a mutant allele with an inactivating mutation in the kinase domain decreased expression of class IVa by 50% and partially reversed resistance to paclitaxel. Expression of oncogenic epidermal growth factor receptor family members is associated with modulation of both beta-tubulin isotype expression and paclitaxel resistance in cells transformed by expression of the receptor. This effect on tubulin expression may modulate drug resistance in human malignancies that express these oncogenes.

Constitutive activation of phosphatidylinositol 3-kinase by a naturally occurring mutant epidermal growth factor receptor

The most frequently found alteration of the epidermal growth factor receptor (EGFR) in human tumors is a deletion of exons 2-7. This receptor, termed EGFRvIII, can transform NIH 3T3 cells, and the frequent expression of this variant implies that it confers a selective advantage upon tumor cells in vivo. Although EGFRvIII is a constitutively activated tyrosine kinase, there is no increase in Ras.GTP levels and low levels of mitogen-activated protein kinase activity in NIH 3T3 cells expressing this variant. We investigated whether phosphatidylinositol (PI) 3-kinase was an effector in transformation by the EGFRvIII. High levels of PI 3-kinase activity were constitutively present in EGFRvIII-transformed cells and were dependent upon the kinase activity of the receptor. While mitogen-activated protein kinase activity was quickly down-regulated to basal levels after 12 h of continuous EGFR activation, there was a 3-fold increase in PI 3-kinase activity in cells expressing normal EGFR and an 8-fold increase in cells expressing EGFRvIII after 48 h. This increased activity may reflect enhanced binding to EGFRvIII and the presence of novel PI 3-kinase isoforms. Treatment with the PI 3-kinase inhibitors wortmannin and LY294002 blocked both anchorage-independent growth and growth in low serum media and also resulted in morphological reversion of EGFRvIII-transformed cells. These results support an essential role for PI 3-kinase in transformation by this EGFR variant.

Epidermal growth factor receptor stimulation of diacylglycerol kinase

The epidermal growth factor receptor (EGFR) activates formation of the phospholipid signal messenger phosphatidic acid (PA) on ligand binding. We explored the effects of chronic EGF stimulation on cellular PA in NIH3T3 cells expressing intact EGFR a mutant EGFR (EGFRvIII). The presence of EGFRvIII increased PA levels to twice those induced by chronic EGFR activation. Fatty acid methyl ester analysis revealed a marked increase in oleic acid containing PA. No apparent increase in phospholipase D (PLD) activity was detected, and diacylglycerol (DAG) kinase assays demonstrated a marked preference for dioleoyl DAG in the presence of activated EGFR or EGFRvIII. Levels of PA which were lower than would be predicted by DAG kinase activation are explained by increased phosphatidate phosphohydrolase activity. Specific inhibitors of EGFR kinase and DAG kinase suppressed DAG kinase activation and PA production by EGFRvIII. EGFR kinase activation by chronic exposure to ligand or by deletional mutation stimulates formation of a specific form of signalling PA.

Transformational and altered signal transduction by a naturally occurring mutant EGF receptor

An amino-truncated variant form of the epidermal growth factor receptor (EGFRvIII) has been identified in human brain, breast, lung and ovarian tumors. We have found that overexpression of this mutant EGF receptor in NIH3T3 cells results in transformation as a result of the activation of the receptor kinase via ligand-independent dimerization. Transformation was correlated with tyrosine phosphorylation of only a subset of the proteins observed in cells overexpressing the normal EGF receptor. This suggested that further studies on cells expressing the EGFRvIII might provide insights into the pathways most relevant to transformation. In clones expressing high levels of mutant EGF receptor, the levels of both Grb2 and SHC were decreased. Despite this decrease, much of the endogenous Grb2 immunoprecipitated with EGFRvIII. Interestingly, no increase in ras-GTP loading was found in clones expressing the EGFRvIII and MAP kinase assays indicated only a small increase in activity. These results indicate that high-level expression of the EGFRvIII induces down-regulation of the ras-MAP kinase pathway and that other components involved in EGF receptor signal transduction may play a greater role in neoplastic transformation by the EGFRvIII.

Differential modulation of mitogen-activated protein (MAP) kinase/extracellular signal-related kinase kinase and MAP kinase activities by a mutant epidermal growth factor receptor

A paradigm has been established whereby mutant tyrosine kinase receptors such as the v-erbB and v-fms gene products function as oncoproteins in the absence of ligand. A spontaneously occurring deletional mutant of the human epidermal growth factor receptor (EGFR-vIII) has been isolated from astrocytic neoplasms and transforms NIH3T3 cells in the absence of ligand. The EGFRvIII is constitutively complexed with the majority of cellular GRB2, suggesting a link to the Ras-Mitogen-activated protein (MAP) kinase pathway (D. Moscatello, R. B. Montgomery, P. Sundareshan, H. McDanel, M. Y. Wong, and A. J. Wong, submitted for publication). In this report, we document that expression of EGFRvIII in fibroblasts is associated with downstream activation of mitogen-activated protein (MAP) kinase/extracellular signal-regulated kinase (MEK) and modest activation of p42 and p44 MAP kinases. The presence of EGFRvIII suppresses activation of p42 and p44 MAP kinases by phorbol 12-myristate 13-acetate (PMA) and serum; however, MEK activation by PMA is not suppressed by EGFRvIII. Basal and PMA-stimulated MAP kinase activity in EGFRvIII-transfected cells is augmented by the tyrosine phosphatase inhibitor sodium vanadate. EGFR-vIII is capable of transducing downstream signals through MAP kinase as evidenced by activation of cytoplasmic phospholipase A2 at levels similar to that induced by intact EGFR. Our results suggest that EGFR-vIII constitutively activates downstream signal transduction through MAP kinase, and this chronic stimulation of the MAP kinase pathway may represent one means by which mutant EGFR transduces an oncogenic signal.