Development and validation of circulating tumour cell enumeration (Epic Sciences) as a prognostic biomarker in men with metastatic castration-resistant prostate cancer.

PURPOSE: To evaluate the prognostic significance of circulating tumour cell (CTC) number determined on the Epic Sciences platform in men with metastatic castration-resistant prostate cancer (mCRPC) treated with an androgen receptor signalling inhibitor (ARSI). PATIENTS AND METHODS: A pre-treatment blood sample was collected from men with progressing mCRPC starting either abiraterone or enzalutamide as a first-, second- or third-line systemic therapy at Memorial Sloan Kettering Cancer Center (Discovery cohort, N = 171) or as a first- or second-line therapy as part of the multicenter PROPHECY trial (NCT02269982) (Validation cohort, N = 107). The measured CTC number was then associated with overall survival (OS) in the Discovery cohort, and progression-free survival (PFS) and OS in the Validation cohort. CTC enumeration was also performed on a concurrently obtained blood sample using the CellSearch® Circulating Tumor Cell Kit. RESULTS: In the MSKCC Discovery cohort, CTC count was a statistically significant prognostic factor of OS as a dichotomous (<3 CTCs/mL versus ≥ 3 CTCs/mL; hazard ratio [HR] = 1.8 [95% confidence interval {CI} 1.3-3.0]) and a continuous variable when adjusting for line of therapy, presence of visceral metastases, prostate-specific antigen, lactate dehydrogenase and alkaline phosphatase. The findings were validated in an independent datas et from PROPHECY (HR [95% CI] = 1.8 [1.1-3.0] for OS and 1.7 [1.1-2.9] for PFS). A strong correlation was also observed between CTC counts determined in matched samples on the CellSearch® and Epic platforms (r = 0.84). CONCLUSION: The findings validate the prognostic significance of pretreatment CTC number determined on the Epic Sciences platform for predicting OS in men with progressing mCRPC starting an ARSI.

Circulating tumour cell increase as a biomarker of disease progression in metastatic castration-resistant prostate cancer patients with low baseline CTC counts.

Background: The development of treatment response and surrogate biomarkers for advanced prostate cancer care is an unmet clinical need. Patients with baseline circulating tumour cell (BLCTCs) counts <5/7.5 mL represent a good prognosis subgroup but are non-evaluable for response assessment (decrease in CTCs). The aim of the study is to determine the value of any increase in CTCs (CTC progression) as an indicator of progression in prostate cancer patients with low pre-treatment CTCs (<5). Patients and methods: We carried out a post hoc analysis of patients with BLCTCs < 5 treated in the COU-AA-301 (abiraterone or placebo + prednisone) and IMMC-38 (chemotherapy) trials. The association of CTC progression (increase in CTCs at 4, 8 or 12 weeks) with overall survival (OS) was evaluated in multi-variable Cox regression models. Performance of survival models with and without CTC progression was evaluated by calculating ROC curve area under the curves (AUCs) and weighted c-indices. Results: Overall, 511 patients with CTCs < 5 (421 in COU-AA-301 and 90 in IMMC-38) were selected; 212 (41.7%) had CTC progression at 4, 8 or 12 weeks after treatment initiation. CTC progression was associated with significantly worse OS [27.1 versus 15.1 m; hazard ratio (HR) 3.4 (95% confidence interval [CI] 2.5-4.5; P < 0.001)], independent of baseline CTCs and established clinical variables. Adding CTC progression to the OS model significantly improved ROC AUC (0.77 versus 0.66; P < 0.001). Models including CTC progression had superior ROC AUC (0.77 versus 0.69; P < 0.001) and weighted c-index [0.750 versus 0.705; delta c-index: 0.045 (95% CI 0.019-0.071)] values than those including CTC conversion (increase to CTCs ≥ 5). In COU-AA-301, the impact of CTC progression was independent of treatment arm. Conclusions: Increasing CTCs during the first 12 weeks of treatment are independently associated with worse OS from advanced prostate cancer in patients with baseline CTCs < 5 treated with abiraterone or chemotherapy and improve models with established prognostic variables. These findings must be prospectively validated.

Androgen receptor mutations in patients with castration-resistant prostate cancer treated with apalutamide.

BACKGROUND: Mutations in the androgen receptor (AR) ligand-binding domain (LBD), such as F877L and T878A, have been associated with resistance to next-generation AR-directed therapies. ARN-509-001 was a phase I/II study that evaluated apalutamide activity in castration-resistant prostate cancer (CRPC). Here, we evaluated the type and frequency of 11 relevant AR-LBD mutations in apalutamide-treated CRPC patients. PATIENTS AND METHODS: Blood samples from men with nonmetastatic CRPC (nmCRPC) and metastatic CRPC (mCRPC) pre- or post-abiraterone acetate and prednisone (AAP) treatment (≥6 months' exposure) were evaluated at baseline and disease progression in trial ARN-509-001. Mutations were detected in circulating tumor DNA using a digital polymerase chain reaction-based method known as BEAMing (beads, emulsification, amplification and magnetics) (Sysmex Inostics' GmbH). RESULTS: Of the 97 total patients, 51 had nmCRPC, 25 had AAP-naïve mCRPC, and 21 had post-AAP mCRPC. Ninety-three were assessable for the mutation analysis at baseline and 82 of the 93 at progression. The overall frequency of detected AR mutations at baseline was 7/93 (7.5%) and at progression was 6/82 (7.3%). Three of the 82 (3.7%) mCRPC patients (2 AAP-naïve and 1 post-AAP) acquired AR F877L during apalutamide treatment. At baseline, 3 of the 93 (3.2%) post-AAP patients had detectable AR T878A, which was lost after apalutamide treatment in 1 patient who continued apalutamide treatment for 12 months. CONCLUSIONS: The overall frequency of detected mutations at baseline (7.5%) and progression (7.3%) using the sensitive BEAMing assay was low, suggesting that, based on this assay, AR-LBD mutations such as F877L and T878A are not common contributors to de novo or acquired resistance to apalutamide. CLINICALTRIALS.GOV IDENTIFIER: NCT01171898.

Periprostatic adipose inflammation is associated with high-grade prostate cancer.

BACKGROUND: Obesity, a cause of subclinical inflammation, is associated with increased risk of high-grade prostate cancer (PC) and poor outcomes. Whether inflammation occurs in periprostatic white adipose tissue (WAT), and contributes to the negative impact of obesity on PC aggressiveness, is unknown. METHODS: In a single-center, cross-sectional design, men with newly diagnosed PC undergoing radical prostatectomy were eligible for study participation. The primary objective was to examine the prevalence of periprostatic WAT inflammation defined by the presence of crown-like structures (CLS-P) as detected by CD68 immunohistochemistry. Secondary objectives were to explore the clinical and systemic correlates of periprostatic WAT inflammation. Tumor characteristics and host factors including BMI, adipocyte diameter, and circulating levels of lipids, adipokines, and other metabolic factors were measured. Wilcoxon rank-sum, Chi-square, or Fisher's exact tests, and generalized linear regression were used to examine the association between WAT inflammation and tumor and host characteristics. RESULTS: Periprostatic fat was collected from 169 men (median age 62 years; median BMI 28.3). Periprostatic WAT inflammation was identified in 49.7% of patients and associated with higher BMI (P=0.02), larger adipocyte size (P=0.004) and Gleason grade groups IV/V tumors (P=0.02). The relationship between WAT inflammation and high Gleason grade remained significant after adjusting for BMI (P=0.04). WAT inflammation correlated with higher circulating levels of insulin, triglycerides, and leptin/adiponectin ratio, and lower high density lipoprotein cholesterol, compared to those without WAT inflammation (P's <0.05). CONCLUSION: Periprostatic WAT inflammation is common in this cohort of men with PC and is associated with high-grade PC.

A prognostic index model for predicting overall survival in patients with metastatic castration-resistant prostate cancer treated with abiraterone acetate after docetaxel.

BACKGROUND: Few prognostic models for overall survival (OS) are available for patients with metastatic castration-resistant prostate cancer (mCRPC) treated with recently approved agents. We developed a prognostic index model using readily available clinical and laboratory factors from a phase III trial of abiraterone acetate (hereafter abiraterone) in combination with prednisone in post-docetaxel mCRPC. PATIENTS AND METHODS: Baseline data were available from 762 patients treated with abiraterone-prednisone. Factors were assessed for association with OS through a univariate Cox model and used in a multivariate Cox model with a stepwise procedure to identify those of significance. Data were validated using an independent, external, population-based cohort. RESULTS: Six risk factors individually associated with poor prognosis were included in the final model: lactate dehydrogenase > upper limit of normal (ULN) [hazard ratio (HR) = 2.31], Eastern Cooperative Oncology Group performance status of 2 (HR = 2.19), presence of liver metastases (HR = 2.00), albumin ≤4 g/dl (HR = 1.54), alkaline phosphatase > ULN (HR = 1.38) and time from start of initial androgen-deprivation therapy to start of treatment ≤36 months (HR = 1.30). Patients were categorized into good (n = 369, 46%), intermediate (n = 321, 40%) and poor (n = 107, 13%) prognosis groups based on the number of risk factors and relative HRs. The C-index was 0.70 ± 0.014. The model was validated by the external dataset (n = 286). CONCLUSION: This analysis identified six factors used to model survival in mCRPC and categorized patients into three distinct risk groups. Prognostic stratification with this model could assist clinical practice decisions for follow-up and monitoring, and may aid in clinical trial design. TRIAL REGISTRATION NUMBERS: NCT00638690.

Does Gleason score at initial diagnosis predict efficacy of abiraterone acetate therapy in patients with metastatic castration-resistant prostate cancer? An analysis of abiraterone acetate phase III trials.

BACKGROUND: The usefulness of Gleason score (<8 or ≥8) at initial diagnosis as a predictive marker of response to abiraterone acetate (AA) plus prednisone in patients with metastatic castration-resistant prostate cancer (mCRPC) was explored retrospectively. PATIENTS AND METHODS: Initial diagnosis Gleason score was obtained in 1048 of 1195 (COU-AA-301, post-docetaxel) and 996 of 1088 (COU-AA-302, chemotherapy-naïve) patients treated with AA 1 g plus prednisone 5 mg twice daily by mouth or placebo plus prednisone. Efficacy end points included radiographic progression-free survival (rPFS) and overall survival (OS). Distributions and medians were estimated by Kaplan-Meier method and hazard ratio (HR) and 95% confidence interval (CI) by Cox model. RESULTS: Baseline characteristics were similar across studies and treatment groups. Regardless of Gleason score, AA treatment significantly improved rPFS in post-docetaxel [Gleason score <8: median, 6.4 versus 5.5 months (HR = 0.70; 95% CI 0.56-0.86), P = 0.0009 and Gleason score ≥8: median, 5.6 versus 2.9 months (HR = 0.58; 95% CI 0.48-0.72), P < 0.0001] and chemotherapy-naïve patients [Gleason score <8: median, 16.5 versus 8.2 months (HR = 0.50; 95% CI 0.40-0.62), P < 0.0001 and Gleason score ≥8: median, 13.8 versus 8.2 months (HR = 0.61; 95% CI 0.49-0.76), P < 0.0001]. Clinical benefit of AA treatment was also observed for OS, prostate-specific antigen (PSA) response, objective response and time to PSA progression across studies and Gleason score subgroups. CONCLUSION: OS and rPFS trends demonstrate AA treatment benefit in patients with pre- or post-chemotherapy mCRPC regardless of Gleason score at initial diagnosis. The initial diagnostic Gleason score in patients with mCRPC should not be considered in the decision to treat with AA, as tumour metastases may no longer reflect the histology at the time of diagnosis. CLINICAL TRIALS NUMBER: COU-AA-301 (NCT00638690); COU-AA-302 (NCT00887198).

Management of patients with advanced prostate cancer: recommendations of the St Gallen Advanced Prostate Cancer Consensus Conference (APCCC) 2015.

The first St Gallen Advanced Prostate Cancer Consensus Conference (APCCC) Expert Panel identified and reviewed the available evidence for the ten most important areas of controversy in advanced prostate cancer (APC) management. The successful registration of several drugs for castration-resistant prostate cancer and the recent studies of chemo-hormonal therapy in men with castration-naïve prostate cancer have led to considerable uncertainty as to the best treatment choices, sequence of treatment options and appropriate patient selection. Management recommendations based on expert opinion, and not based on a critical review of the available evidence, are presented. The various recommendations carried differing degrees of support, as reflected in the wording of the article text and in the detailed voting results recorded in supplementary Material, available at Annals of Oncology online. Detailed decisions on treatment as always will involve consideration of disease extent and location, prior treatments, host factors, patient preferences as well as logistical and economic constraints. Inclusion of men with APC in clinical trials should be encouraged.

Enzalutamide: Development from bench to bedside.

Prostate tissue, whether benign or malignant, is heavily dependent on androgen receptor (AR) signaling for growth and proliferation. Androgen deprivation therapy has been standard of care for management of metastatic prostate cancer for the past 70 years. AR antagonists were developed to further abrogate signaling through this pathway by competitive inhibition of the receptor. First-generation compounds such as bicalutamide had modest efficacy, and in the setting of AR overexpression or specific mutations in the AR ligand-binding domain, these early compounds had partial agonist properties that could stimulate tumor growth. Enzalutamide was developed to overcome these deficiencies, and here, we present the story of its preclinical discovery, clinical development, and ultimate approval as a standard-of-care therapy for castration-resistant prostate cancer. Also discussed are ongoing efforts to elucidate mechanisms of resistance to this agent as well as studies that are investigating its role in other prostate cancer disease states and other cancer types.

Androgen dynamics and serum PSA in patients treated with abiraterone acetate.

BACKGROUND: We analyzed the potential of abiraterone acetate (henceforth abiraterone) to reduce androgen levels below lower limits of quantification (LLOQ) and explored the association with changes in PSA decline in metastatic castration-resistant prostate cancer (mCRPC) patients. METHODS: COU-AA-301 is a 2:1 randomized, double-blind, placebo-controlled study comparing abiraterone (1000 mg q.d.) plus low-dose prednisone (5 mg b.i.d.) with placebo plus prednisone in mCRPC patients post docetaxel. Serum testosterone, androstenedione and dehydroepiandrosterone sulfate from baseline to week 12 were measured by novel ultrasensitive two-dimensional liquid chromatography coupled to tandem mass spectrometry assays in a subset of subjects in each arm (abiraterone plus prednisone, n=80; prednisone, n=38). The association between PSA response (< or =50% baseline) and undetectable androgens (week 12 androgen level below LLOQ) was analyzed using logistic regression. RESULTS: A significantly greater reduction in serum androgens was observed with abiraterone plus prednisone versus prednisone (all P < or = 0.0003), reaching undetectable levels for testosterone (47.2% versus 0%, respectively). A positive association was observed between achieving undetectable serum androgens and PSA decline (testosterone: odds ratio=1.54; 95% confidence interval: 0.546-4.347). Reduction of androgens to undetectable levels did not occur in all patients achieving a PSA response, and a PSA response did not occur in all patients achieving undetectable androgen levels. CONCLUSIONS: Abiraterone plus prednisone significantly reduced serum androgens, as measured by ultrasensitive assays and was generally associated with PSA response. However, androgen decline did not uniformly predict PSA decline suggesting ligand-independent or other mechanisms for mCRPC progression.

Improved outcomes in elderly patients with metastatic castration-resistant prostate cancer treated with the androgen receptor inhibitor enzalutamide: results from the phase III AFFIRM trial.

BACKGROUND: The randomized, double-blind phase III AFFIRM trial demonstrated that enzalutamide, an oral androgen receptor inhibitor, significantly prolonged overall survival (OS) [median 18.4 versus 13.6 months (hazard ratio, HR) 0.63 (95% confidence interval, CI, 0.53-0.75); P<0.001] compared with placebo in patients with metastatic castration-resistant prostate cancer who received prior docetaxel chemotherapy. PATIENTS AND METHODS: A post hoc analysis was carried out to assess the efficacy and safety of enzalutamide on outcomes in younger (<75 years) and elderly (≥75 years) patients in the AFFIRM population. Statistics are presented by age group (<75 years, ≥75 years) for efficacy outcomes of OS, radiographic progression-free survival (rPFS), time to prostate-specific antigen (PSA) progression, PSA response, and safety. RESULTS: OS was significantly improved with enzalutamide over placebo in patients<75 years [median not yet reached versus 13.6 months; HR 0.63 (95% CI 0.52-0.78), P<0.001] and in patients ≥75 years [median 18.2 versus 13.3 months; HR 0.61 (95% CI 0.43-0.86), P=0.004], respectively. rPFS was similarly improved in both the younger [HR 0.45 (95% CI 0.38-0.53), P<0.001] and elderly patient cohorts [HR 0.27 (95% CI 0.20-0.37), P<0.001] relative to placebo, as were time to PSA progression and PSA response. Adverse events (AEs) were similar between the two enzalutamide age groups, with the exception of an increase in patients≥75 years in the rates of all grade peripheral edema (22.1% versus 12.5%), fatigue (39.7% versus 31.6%), and diarrhea (26.6% versus 19.6%). The overall grade≥3 AE rates were low with no major difference in frequency or severity between age groups or treatment arms. Five patients were reported with seizure events; three patients<75 years and two patients ≥75 years. CONCLUSIONS: Enzalutamide significantly improves outcomes in both younger (<75 years) and elderly patients (≥75 years), with comparable safety and tolerability.

Exploratory analysis of the visceral disease subgroup in a phase III study of abiraterone acetate in metastatic castration-resistant prostate cancer.

BACKGROUND: Visceral disease, non-nodal soft-tissue metastases predominantly involving the lung and liver, is a negative prognostic factor in patients with metastatic castration-resistant prostate cancer (mCRPC). An exploratory analysis of COU-AA-301 assessed whether abiraterone acetate (AA) improved overall survival (OS) in mCRPC patients with visceral disease progressing post docetaxel. METHODS: In COU-AA-301, post-docetaxel mCRPC patients were randomized 2:1 to AA 1000 mg (n=797) or placebo (n=398) once daily, each with prednisone 5 mg b.i.d. The primary end point was OS; secondary end points included radiographic progression-free survival (rPFS), PSA response rate and objective response rate (ORR). Treatment effects in visceral disease (n=352) and non-visceral disease (n=843) subsets were examined using final data (775 OS events). RESULTS: AA plus prednisone produced similar absolute improvement in median OS in patients with (4.6 months) and without (4.8 months) visceral disease versus prednisone; hazard ratios (HRs) were 0.79 (95% confidence interval (CI): 0.60-1.05; P=0.102) and 0.69 (95% CI: 0.58-0.83; P<0.0001), respectively. Treatment with AA plus prednisone significantly and comparably improved secondary endpoint outcomes versus prednisone in both the subsets: the HRs for rPFS were 0.60 (95% CI: 0.46-0.78; P=0.0002) and 0.68 (95% CI: 0.58-0.80; P<0.0001) in visceral and non-visceral disease subsets, respectively. PSA response rates were 28% versus 7% in the visceral disease subsets and 30% versus 5% in the non-visceral disease subsets (both P<0.0001), and ORRs were 11% versus 0% (P=0.0058) and 19% versus 5% (P=0.0010), respectively. The incidence of grade 3/4 adverse events was similar between the subsets and between the treatment arms in each subset. Adverse events related to CYP17 blockade were increased in the AA arms and were similar in patients with or without visceral disease. CONCLUSIONS: AA plus prednisone provides significant clinical benefit, including improvements in OS and secondary end points, in post-docetaxel mCRPC patients with or without baseline visceral disease. The presence of visceral disease does not preclude clinical benefit from abiraterone.

First-in-human Phase I study of EZN-4176, a locked nucleic acid antisense oligonucleotide to exon 4 of the androgen receptor mRNA in patients with castration-resistant prostate cancer.

BACKGROUND: Prostate cancer remains dependent of androgen receptor (AR) signalling, even after emergence of castration resistance. EZN-4176 is a third-generation antisense oligonucleotide that binds to the hinge region (exon 4) of AR mRNA resulting in full-length AR mRNA degradation and decreased AR protein expression. This Phase I study aimed to evaluate EZN-4176 in men with castration-resistant prostate cancer (CRPC). METHODS: Patients with progressing CRPC were eligible; prior abiraterone and enzalutamide treatment were allowed. EZN-4176 was administered as a weekly (QW) 1-h intravenous infusion. The starting dose was 0.5 mg kg(-1) with a 4-week dose-limiting toxicity (DLT) period and a 3+3 modified Fibonacci dose escalation design. After determination of the DLT for weekly administration, an every 2 weeks schedule was initiated. RESULTS: A total of 22 patients were treated with EZN-4176. At 10 mg kg(-1) QW, two DLTs were observed due to grade 3-4 ALT or AST elevation. No confirmed biochemical or soft tissue responses were observed. Of eight patients with <5 circulating tumour cells at baseline, a conversion to <5 was observed in three (38%) patients. The most common EZN-4176-related toxicities (all grades) were fatigue (59%), reversible abnormalities in liver function tests ALT (41%) and AST (41%) and infusion-related reactions including chills (36%) and pyrexia (14%). CONCLUSION: Activity of EZN-4176 at the doses and schedules explored was minimal. The highest dose of 10 mg kg(-1) QW was associated with significant but reversible transaminase elevation.

Ipilimumab alone or in combination with radiotherapy in metastatic castration-resistant prostate cancer: results from an open-label, multicenter phase I/II study.

BACKGROUND: This phase I/II study in patients with metastatic castration-resistant prostate cancer (mCRPC) explored ipilimumab as monotherapy and in combination with radiotherapy, based on the preclinical evidence of synergistic antitumor activity between anti-CTLA-4 antibody and radiotherapy. PATIENTS AND METHODS: In dose escalation, 33 patients (≥6/cohort) received ipilimumab every 3 weeks × 4 doses at 3, 5, or 10 mg/kg or at 3 or 10 mg/kg + radiotherapy (8 Gy/lesion). The 10-mg/kg cohorts were expanded to 50 patients (ipilimumab monotherapy, 16; ipilimumab + radiotherapy, 34). Evaluations included adverse events (AEs), prostate-specific antigen (PSA) decline, and tumor response. RESULTS: Common immune-related AEs (irAEs) among the 50 patients receiving 10 mg/kg ± radiotherapy were diarrhea (54%), colitis (22%), rash (32%), and pruritus (20%); grade 3/4 irAEs included colitis (16%) and hepatitis (10%). One treatment-related death (5 mg/kg group) occurred. Among patients receiving 10 mg/kg ± radiotherapy, eight had PSA declines of ≥50% (duration: 3-13+ months), one had complete response (duration: 11.3+ months), and six had stable disease (duration: 2.8-6.1 months). CONCLUSIONS: In mCRPC patients, ipilimumab 10 mg/kg ± radiotherapy suggested clinical antitumor activity with disease control and manageable AEs. Two phase III trials in mCRPC patients evaluating ipilimumab 10 mg/kg ± radiotherapy are ongoing. ClinicalTrials.gov identifier: NCT00323882.

Effect of abiraterone acetate on fatigue in patients with metastatic castration-resistant prostate cancer after docetaxel chemotherapy.

BACKGROUND: Fatigue is a common, debilitating side-effect of prostate cancer and its treatment. Patient-reported fatigue was evaluated as part of COU-AA-301, a randomized, placebo-controlled, phase III trial of abiraterone acetate and prednisone versus placebo and prednisone in metastatic castration-resistant prostate cancer (mCRPC) patients after docetaxel chemotherapy. This is the first phase III study in advanced prostate cancer to evaluate fatigue outcomes using a validated fatigue-specific instrument. PATIENTS AND METHODS: The Brief Fatigue Inventory (BFI) questionnaire was used to measure patient-reported fatigue intensity and fatigue interference with activities of daily life. All analyses were conducted using prespecified responder definitions of clinically meaningful changes. RESULTS: A total of 797 patients were randomized to abiraterone acetate and prednisone, and 398 were randomized to placebo and prednisone. Compared with prednisone alone, in patients with clinically significant fatigue at baseline, abiraterone acetate and prednisone significantly increased the proportion of patients reporting improvement in fatigue intensity (58.1% versus 40.3%, P = 0.0001), improved fatigue interference (55.0% versus 38.0%, P = 0.0075), and accelerated improvement in fatigue intensity (median 59 days versus 194 days, P = 0.0155). CONCLUSIONS: In patients with mCRPC progressing after docetaxel chemotherapy, abiraterone acetate and prednisone yielded clinically meaningful improvements in patient-reported fatigue compared with prednisone alone.

A phase I/IIA study of AGS-PSCA for castration-resistant prostate cancer.

BACKGROUND: This first-in-human phase I/IIA study was designed to evaluate the safety and pharmacokinetics (PKs) of AGS-PSCA a fully human monoclonal antibody directed to prostate stem cell antigen (PSCA) in progressive castration-resistant prostate cancer. PATIENTS AND METHODS: Twenty-nine patients were administered infusions of AGS-PSCA (1-40 mg/kg) every 3 weeks for 12 weeks; 18 final patients received a 40-mg/kg loading dose followed by 20-mg/kg repeat doses. Primary end points were safety and PK. Immunogenicity, antitumor activity and circulating tumor cells were also evaluated. RESULTS: No drug-related serious adverse events were noted. Dose escalation stopped before reaching the maximum tolerated dose as target concentrations were achieved. Drug levels accumulated linearly with dose and the mean terminal half-life was 2-3 weeks across dose levels. The 40-mg/kg loading dose followed by repeated 20-mg/kg doses yielded serum drug concentrations above the projected minimum therapeutic threshold after two to three doses without excessive drug accumulation or toxicity. Significant antitumor effects were not seen. CONCLUSIONS: A 40-mg/kg loading dose followed by 20-mg/kg infusions every 3 weeks is the recommended phase II dose of AGS-PSCA. PSCA is a promising drug target and studies in prostate and other relevant solid tumors are planned.

ADAM12 is highly expressed in carcinoma-associated stroma and is required for mouse prostate tumor progression.

The interaction between stromal cells and tumor cells is emerging as a critical aspect of tumor progression. Yet there is a paucity of molecular markers for cells participating in such interactions, and only few genes are known to play a critical role in this process. Here, we describe the identification of ADAM12 (a disintegrin and metalloprotease 12) as a novel marker for a subpopulation of stromal cells that are adjacent to epithelial tumor cells in three mouse carcinoma models (models for prostate, breast and colon cancer). Moreover, we show that ADAM12 is essential for tumor development and progression in the W10 mouse model for prostate cancer. These results suggest that ADAM12 might be a useful marker for stromal cells in mouse tumors that are likely to participate in stromal/tumor cell crosstalk, and that ADAM12 is a potential target for design of drugs that prevent carcinoma growth.

Effective antigen cross-presentation by prostate cancer patients' dendritic cells: implications for prostate cancer immunotherapy.

Despite the potency with which dendritic cells (DCs) are able to utilize the exogenous MHC I antigen cross-presentation pathway to cross-present antigen for the activation of killer T cells in model systems, concern about defects in immune function in cancer patients has led to uncertainty regarding whether immune cells derived from patients can effectively be used to generate tumor vaccines. We have undertaken a careful analysis of the potency of using DCs obtained from prostate cancer patients to cross-present antigen derived from human prostate tumor cells for the activation of antigen-specific T cells. Such DCs can be matured ex vivo into functionally active cells and are capable of cross-presenting influenza antigen derived from internalized apoptotic prostate tumor cells. Importantly, we demonstrate effective stimulation of both CD4+ and CD8+ T cells, as evident by production of IFN-gamma, and the ability of CD8+ T cells to differentiate into effector CTLs. These results, defining conditions in which prostate cancer patient DCs can efficiently utilize the cross-presentation pathway and in which apoptotic tumor can serve as a source of antigen for DCs to activate T cells, demonstrate that this system warrants clinical study as a potential immunotherapy.

Pilot study of epothilone B analog (BMS-247550) and estramustine phosphate in patients with progressive metastatic prostate cancer following castration.

BACKGROUND: Several trials have demonstrated that the response proportions to microtubule agents in patients with prostate cancer are increased by the addition of estramustine phosphate (EMP). The epothilone B analog BMS-247550 is a novel microtubule agent that has shown activity in taxane-resistant tumors. We conducted a dose-escalation study to determine a safe dose of BMS-247550 to combine with EMP in patients with metastatic prostate cancer. PATIENTS AND METHODS: Chemotherapy-naive patients with castrate-metastatic prostate cancer were treated with intravenous BMS-247550 and oral EMP (280 mg three times daily for 5 days) every 3 weeks. RESULTS: Thirteen patients were treated at two dose levels (35 and 40 mg/m(2)). Three of six patients treated at 40 mg/m(2) developed grade 4 neutropenia, establishing 35 mg/m(2) as the maximum-tolerated dose. Significant peripheral neuropathy (grade >/= 2) was related to dose level and infusion rate. A decline in prostate-specific antigen (PSA) of >/= 50% was seen in 11 of 12 evaluable patients (92%) (95% confidence interval 76% to 100%). There were objective responses in soft tissue (57%) and bone metastasis (40%). CONCLUSIONS: The phase II dose of BMS-247550 combined with EMP is 35 mg/m(2) over 3 h every 3 weeks. This combination is safe and >/= 50% post-therapy declines in PSA were seen in 11 of 12 patients (92%).