Phase 1b study of enzalutamide plus CC-115, a dual mTORC1/2 and DNA-PK inhibitor, in men with metastatic castration-resistant prostate cancer (mCRPC)

BACKGROUND

CC-115, a dual mTORC1/2 and DNA-PK inhibitor, has promising antitumour activity when combined with androgen receptor (AR) inhibition in pre-clinical models.

METHODS

Phase 1b multicentre trial evaluating enzalutamide with escalating doses of CC-115 in AR inhibitor-naive mCRPC patients (n = 41). Primary endpoints were safety and RP2D. Secondary endpoints included PSA response, time-to-PSA progression, and radiographic progression.

RESULTS

Common adverse effects included rash (31.7% Grades 1-2 (Gr); 31.7% Gr 3), pruritis (43.9% Gr 1-2), diarrhoea (37% Gr 1-2), and hypertension (17% Gr 1-2; 9.8% Gr 3). CC-115 RP2D was 5 mg twice a day. In 40 evaluable patients, 80% achieved ≥50% reduction in PSA (PSA50), and 58% achieved ≥90% reduction in PSA (PSA90) by 12 weeks. Median time-to-PSA progression was 14.7 months and median rPFS was 22.1 months. Stratification by PI3K alterations demonstrated a non-statistically significant trend towards improved PSA50 response (PSA50 of 94% vs. 67%, p = 0.08). Exploratory pre-clinical analysis suggested CC-115 inhibited mTOR pathway strongly, but may be insufficient to inhibit DNA-PK at RP2D.

CONCLUSIONS

The combination of enzalutamide and CC-115 was well tolerated. A non-statistically significant trend towards improved PSA response was observed in patients harbouring PI3K pathway alterations, suggesting potential predictive biomarkers of response to a PI3K/AKT/mTOR pathway inhibitor.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02833883.

A Proposal for the Comprehensive Care of Men on Androgen Deprivation Therapy: Recommendations From the Multidisciplinary Prostate Cancer 360 Working Group

INTRODUCTION

To promote comprehensive care of patients throughout the androgen deprivation therapy (ADT) prescribing process, the Prostate Cancer 360 (PC360) Working Group developed monitoring and management recommendations intended to mitigate or prevent ADT-associated adverse events.

METHODS

The PC360 Working Group included 14 interdisciplinary experts with a dedicated clinical interest in prostate cancer and ADT management. The working group defined challenges associated with ADT adverse event management and then collaboratively developed comprehensive care recommendations intended to be practical for ADT prescribers.

RESULTS

The PC360 Working Group developed both overarching recommendations for ADT adverse event management and specific recommendations across 5 domains (cardiometabolic, bone, sexual, psychological, and lifestyle). The working group recommends an interdisciplinary, team-based approach wherein the ADT prescriber retains an oversight role for ADT management while empowering patients and their primary and specialty care providers to manage risk factors. The PC360 recommendations also emphasize the importance of proactive patient education that involves partners or other support providers. Recommended monitoring and assessment tools, risk factor management, and patient counseling points are also included for the 5 identified domains, with an emphasis on lifestyle and behavioral interventions that can improve quality of life and reduce the risk for ADT-associated complications.

CONCLUSIONS

Comprehensive care of patients receiving ADT requires early and ongoing coordinated management of a variety of health domains, including cardiometabolic, bone, sexual, psychological health. Patient education and primary care provider involvement should begin prior to ADT initiation and continue throughout treatment to improve patient and partner quality of life.

Randomized Phase II Multicenter Trial of Abiraterone Acetate With or Without Cabazitaxel in the Treatment of Metastatic Castration-Resistant Prostate Cancer

PURPOSE

Improving clinical outcomes with novel drug combinations to treat metastatic castration-resistant prostate cancer (mCRPC) is challenging. Preclinical studies showed cabazitaxel had superior antitumor efficacy compared with docetaxel. Gene expression profiling revealed divergent effects of these taxanes in cycling cells. mCRPC are RB deficient rendering them hypersensitive to taxanes. These data suggested that upfront treatment with cabazitaxel with abiraterone may affect therapeutic response. We designed a phase II randomized noncomparative trial of abiraterone acetate/prednisone (AAP) or AAP and cabazitaxel (AAP + C) in men with mCRPC to address this hypothesis.

METHODS

This trial of 81 men with mCRPC determined the radiographic progression-free survival (rPFS), prostate-specific antigen (PSA) progression-free survival, overall objective response, and safety of AAP or AAP + C. Equally allocated patients received AAP followed by switching to cabazitaxel upon radiographic progression (arm 1) or upfront with AAP + C (arm 2). Patients were stratified into high-/low-risk groups by the Halabi nomogram. Real-time assessment of RB status and circulating tumor cell (CTC) analysis to correlate with clinical outcomes was exploratory.

RESULTS

Both treatment arms were well-tolerated. Median rPFS in AAP was 6.4 months (95% CI, 3.8 to 10.6) and median overall survival (OS) 18.3 months (95% CI, 14.4 to 37.6), respectively. Fifty-six percent of patients showed ≥50% decline in PSA. Median rPFS in AAP + C was 14.8 months (95% CI, 10.6 to 16.4), and median OS 24.5 months (95% CI, 20.4 to 35.0). There was a ≥50% decline in PSA in 92.1% of men. Neither RB expression in pretherapy tumor biopsy, CTC, or tissue explants identified those who may benefit from AAP + C.

CONCLUSION

AAP + C was safe with improved rPFS, OS duration, and a higher proportion of PSA declines. This suggests that AAP + C given earlier rather than sequentially may benefit some men. Further work is needed to identify this population.

Evaluation of immune-related adverse events (irAE): Utilizing the patient-reported outcomes of the common terminology criteria for adverse events (PRO-CTCAE) in a phase II study of ipilimumab (ipi) in men with castration-sensitive prostate cancer (CSPC)

e24174

Background: Incorporation of the PRO-CTCAE during chemotherapy is associated with fewer ER visits and improved survival. Limited data exist using this tool to capture irAE in immunotherapy trials. We collected select PRO-CTCAEs in a clinical trial evaluating an immune checkpoint inhibitor (ICI) in patients (pts) with CSPC. Methods: Cohort A (Coh A) enrolled de novo metastatic CSPC; Cohort B (Coh B) enrolled recurrent CSPC after radical prostatectomy (RP). Treatment consisted of 4 doses of ipi and 8 months of androgen deprivation therapy (ADT) in Coh A & B, and RP in Coh A. PRO-CTCAEs were collected at each ipi or ADT administration, and during follow-up. PRO-CTCAE items included abdominal pain, diarrhea, fatigue, anorexia, nausea, vomiting, rash and pruritus, with the correspondent attributes of frequency (freq), severity (sev), interference (int), and presence. Results: 16 pts were treated (Coh A: 7; Coh B: 9) with 181 matched pairs of PRO-CTCAE and CTCAE. The study was terminated early for an unfavorable risk:benefit ratio. PRO-CTCAE completion at required visits was 85.4% in Coh A and 98.1% in Coh B. Cohen’s kappa coefficients was lowest for pruritus (k = 0.10, slight agreement) and highest for rash (k = 0.64, moderate agreement). CTCAE captured diarrhea in 10 pts, 4 of whom received steroids. 75% (3/4) of pts receiving steroids graded diarrhea as ‘frequently’ or ‘almost constantly’ on the PRO-CTCAE while 66.7% (4/6) of those who did not receive steroids reported the same frequency. Conclusions: IrAE were more commonly reported and of higher grade by patients using the PRO-CTCAE as compared to clinician reporting, consistent with existing literature in non-ICI studies. Diarrhea as reported by the PRO-CTCAE did not associate with steroid use in this small trial. Further studies are needed to evaluate irAE using PRO-CTCAEs and the potential role in management of these toxicities. Clinical trial information: NCT02020070 . [Table: see text]

A phase II study of the dual mTOR inhibitor MLN0128 in patients with metastatic castration resistant prostate cancer

Background MLN0128 is a first-in-class, dual mTOR inhibitor with potential to outperform standard rapalogs through inhibition of TORC1 and TORC2. This phase II study was designed to assess antitumor activity of MLN0128 in metastatic castration-resistant prostate cancer (mCRPC). Methods Eligible patients had mCRPC previously treated with abiraterone acetate and/or enzalutamide. Five patients started MLN0128 at 5 mg once daily, subsequently dose reduced to 4 mg because of toxicity. Four subsequent patients started MLN0128 at 4 mg daily. Primary endpoint was progression-free survival at 6 months. Results Nine patients were enrolled and median time on treatment was 11 weeks (range: 3-30). Best response was stable disease. All patients had a rise in PSA on treatment, with a median 159% increase from baseline (range: 12-620%). Median baseline circulating tumor cell count was 1 cell/mL (range: 0-40); none had a decrease in cell count posttreatment. Grade ≤ 2 adverse events included fatigue, anorexia, and rash. The most common serious adverse events were grade 3 dyspnea and maculopapular rash. Eight patients discontinued treatment early because of radiographic progression (n = 1), grade 3 toxicity (n = 5), or investigator discretion (n = 2). Four patients had immediate PSA decline following drug discontinuation, suggesting MLN0128 could cause compensatory increase of androgen receptor (AR) activity. Correlative studies of pretreatment and posttreatment biopsy specimens revealed limited inhibition of AKT phosphorylation, 4EBP1 phosphorylation, and eIF4E activity. Conclusions Clinical efficacy of MLN0128 in mCRPC was limited likely due to dose reductions secondary to toxicity, PSA kinetics suggesting AR activation resulting from mTOR inhibition, and poor inhibition of mTOR signaling targets.

A phase II study combining ipilimumab and degarelix with or without radical prostatectomy (RP) in men with newly diagnosed metastatic noncastration prostate cancer (mNCPC) or biochemically recurrent (BR) NCPC

203

Background: Androgen deprivation therapy (ADT) does not completely eliminate disease in mNCPC or BRPC. We explored a multimodality treatment (tx) approach combining ADT with ipilimumab (ipi) with the aim of achieving no evidence of disease or complete elimination of disease, given the potential for cure seen with immunotherapy. Methods: Cohort A (Coh A) enrolled men with ≤ 10 bone metastases treated with induction of degarelix (deg) and ipi prior to RP and subsequent ipi q3 weeks x 3 and 8 months (mos) total of deg. Cohort B (Coh B) opened later and enrolled men with BRNCPC after RP with a doubling time ≤ 12 mos, and received ipi q3 weeks x 4 and 8 mos of deg. The primary endpoint was an undetectable PSA (<0.05) at 12 and 20 mos with non-castrate testosterone. Results: 16 pts (7 Coh A; 9 Coh B) were treated. No Coh A pts experienced immune related toxicities (irAE) that delayed surgery. 4/7 (57%) Coh A pts came off study for irAE, 1 (14%) for insurance reasons, and 2 (29%) completed all protocol requirements. In Coh B 6/9 (67%) pts have completed tx and entered follow-up. Conclusions: A combined modality approach with ipi 10mg/kg, ADT, and RP in mNCPC was associated with limiting toxicities, however 3mg/kg was better tolerated and more feasible in a BRNCPC cohort. One pt in Coh A (14%) had an undetectable PSA with testosterone recovery while evaluation of efficacy for Coh B is ongoing. The role for RP and other immunotherapeutic approaches in NCPC remain viable interests to the field. Clinical trial information: NCT02020070. [Table: see text]

A phase II study of the androgen signaling inhibitor ARN-509 in patients with castration-resistant prostate cancer (CRPC)

TPS4697

Background: ARN-509 is a novel small molecule androgen signaling inhibitor that impairs AR nuclear translocation and binding to DNA, inhibiting tumor growth and promoting apoptosis, with no partial agonist activity. Preclinical data suggests that the maximal therapeutic index of ARN-509 can be achieved at low steady state plasma levels with minimal toxicity (Clegg et al, 2012). Enrollment in the Phase 1 dose escalation study of ARN-509 in patients with progressive CRPC with and without prior chemotherapy was completed in January 2012. The recommended Phase 2 dose of 240 mg was determined based on safety, PSA kinetics, and pharmacokinetic and pharmacodynamic analysis (Rathkopf et al, GU ASCO, 2012). Methods: The primary objective of this Phase 2 study is to determine the PSA response at 12 weeks according to Prostate Cancer Working Group 2 (PCWG2) Criteria (Scher et al, 2008). Three expansion cohorts will enroll a total of 80-90 patients for treatment with 240 mg continuous oral ARN-509 daily. These cohorts include: 1) non-metastatic treatment-naïve CRPC (50 patients); 2) chemotherapy-naïve metastatic (m) CRPC (20 patients); and 3) chemotherapy-naïve, post abiraterone mCRPC (10-20 patients). The effect of food on the PK of ARN-509 and the effect of ARN-509 on ventricular repolarization will also be evaluated. Phase 2 enrollment is ongoing. DOD/PCF PCCTC trial sponsored by Aragon Pharmaceuticals. NCT01171898.

A phase I study of the androgen signaling inhibitor ARN-509 in patients with metastatic castration-resistant prostate cancer (mCRPC)

4548

Background: ARN-509 is a novel small molecule AR antagonist that impairs AR nuclear translocation and binding to DNA, inhibiting tumor growth and promoting apoptosis, with no partial agonist activity. (Clegg et al., 2012) We conducted a phase I trial to assess safety, pharmacokinetics (PK), and determine the recommended phase II dose (RP2D). Methods: Eligible patients with mCRPC received ARN-509 orally on a continuous daily dosing schedule. Seven doses (30, 60, 90, 120, 180, 240, and 300 mg) were tested using standard 3x3 dose escalation criteria. Once drug concentrations were achieved that met or exceeded optimal levels predicted preclinically, an additional 2 dose levels were tested to further confirm the safety margin of ARN-509 (390 and 480 mg). Anti-tumor activity was assessed by PSA, radiographic responses, and FDHT-PET imaging. Results: Thirty patients were enrolled. The most common grades 1-2 treatment-related adverse events were fatigue (38%), nausea (29%), and pain (24%). There was only 1 treatment-related grade 3 adverse event (abdominal pain) at 300 mg, possibly related to a higher pill burden. PK was shown to be linear and dose-dependent. At 12 weeks, 42% of patients have had ≥ 50% PSA declines. Eleven (37%) patients have discontinued the study due to progression, with the longest patient still on study for more than 16 months. FDHT-PET imaging demonstrated AR blockade at 4 weeks across multiple dose levels. Conclusions: In this phase I study, ARN-509 was shown to be safe and well tolerated with linear PK. Based on promising activity across all dose levels and pharmacodynamic evidence of AR antagonism, an optimal biologic dose of 240 mg daily was selected for phase II investigation. DOD/PCF PCCTC trial sponsored by Aragon Pharmaceuticals.

A phase I trial of docetaxel and pulse-dose 17-allylamino-17-demethoxygeldanamycin in adult patients with solid tumors

PURPOSE

To define maximum tolerated dose (MTD), clinical toxicities, and pharmacokinetics of 17-allylamino-17-demethoxygeldanamycin (17-AAG) when administered in combination with docetaxel once every 21 days in patients with advanced solid tumor malignancies.

EXPERIMENTAL DESIGN

Docetaxel was administered over 1 h at doses of 55, 70, and 75 mg/m(2). 17-AAG was administered over 1-2 h, following the completion of the docetaxel infusion, at escalating doses ranging from 80 to 650 mg/m(2) in 12 patient cohorts. Serum was collected for pharmacokinetic and pharmacodynamic studies during cycle 1. Docetaxel, 17-AAG, and 17-AG levels were determined by high-performance liquid chromatography. Biologic effects of 17-AAG were monitored in peripheral blood mononuclear cells by immunoblot.

RESULTS

Forty-nine patients received docetaxel and 17-AAG. The most common all-cause grade 3 and 4 toxicities were leukopenia, lymphopenia, and neutropenia. An MTD was not defined; however, three dose-limiting toxicities were observed, including 2 incidences of neutropenic fever and 1 of junctional bradycardia. Dose escalation was halted at docetaxel 75 mg/m(2)-17-AAG 650 mg/m(2) due to delayed toxicities attributed to patient intolerance of the DMSO-based 17-AAG formulation. Of 46 evaluable patients, 1 patient with lung cancer experienced a partial response. Minor responses were observed in patients with lung, prostate, melanoma, and bladder cancers. A correlation between reduced docetaxel clearance and 17-AAG dose level was observed.

CONCLUSIONS

The combination of docetaxel and 17-AAG was well tolerated in adult patients with solid tumors, although patient intolerance to the DMSO formulation precluded further dose escalation. The recommended phase II dose is docetaxel 70 mg/m(2) and 17-AAG 500 mg/m(2).

A phase I dose escalation trial of vaccine replicon particles (VRP) expressing prostate-specific membrane antigen (PSMA) in patients (pts) with castration-resistant prostate cancer (CRPC): Preliminary results

140

Background: Prostate-specific membrane antigen (PSMA), a type II transmembrane protein overexpressed in prostate cells as they emerge into the androgen-independent state, remains a target to which vaccines with novel adjuvants or naked DNA has been directed. The PSMA-Viral Replicon Package (VRP) is a propagation-defective vector system from an attentuated strain of an alpha virus (VEE) encoding PSMA for use as a vaccine in prostate cancer. The PSMA gene is encoded by a subgenomic messenger RNA (mRNA), leading to high level expression of PSMA protein and presentation to the immune system.. We report preliminary results of a first in human trial using PSMA VRP to elicit immune responses targeting PSMA.

Methods: Up to 18 pts with chemotherapy naïve CRPC metastatic to bone or soft tissue were permitted with 12 pts enrolled with ECOG status of 0 or 1. PSMA VRP was administered SC doses of either 0.9×107 IU or 0.36×108 IU for a total of 5 doses given on weeks 1, 4, 7, 10 and 18. Adverse events, PSA, circulating tumor cells, and clinical disease progression were assessed. Immune assessment was performed on patients' sera by ELISA and flow cytometry of serum binding to PSMA expressing tumor cells (3T3) and cellular (IFN-g EliSpot) components. Patients underwent imaging with bone and CAT scans every 3 months.

Results: Three pts received 0.9×107 IU and 9 received 0.36×108 IU. Of these, 8 pts received all 5 vaccines. Four pts were taken off study for disease progression. One pt at the 0.36×108 continues on study and will be receiving his seventh vaccine. The demographic featuresof the 12 subjects enrolled were similar (mean age 69±11 yrs). No significant adverse events were noted; no aberrant laboratory abnormalities were associated with treatment. Weak humoral responses were observed in 1 patient in the 0.9×107 IU group and in 3 treated at 0.36×108.

Conclusions: In this first-in-man evaluation, vaccination with PSMA VRP appeared to be well-tolerated but does not appear to show impact on disease progression. Further studies are ongoing to assess immune responses and identify potential pathways for enhancement of the PSMA VRP approach.

[Table: see text]

Phase 1 trial of high-dose exogenous testosterone in patients with castration-resistant metastatic prostate cancer

BACKGROUND

Growth of selected castration-resistant prostate cancer (CRPC) cell lines and animal models can be repressed by reexposure to androgens. Low doses of androgens, however, can stimulate tumor growth.

OBJECTIVE

We performed a phase 1 clinical trial to determine the safety of high-dose exogenous testosterone in patients with castration-resistant metastatic prostate cancer (CRMPC).

DESIGN, SETTING, AND PARTICIPANTS

Patients with progressive CRMPC who had been castrate for at least 1 yr received three times the standard replacement dose of transdermal testosterone.

INTERVENTION

Cohorts of 3-6 patients received testosterone for 1 wk, 1 mo, or until disease progression.

MEASUREMENTS

Toxicities, androgen levels, prostate-specific antigen (PSA) assays, computed tomography (CT) scans, bone scintigraphy, positron emission tomography (PET) scans, and metastatic tumor biopsy androgen receptor levels were assessed.

RESULTS AND LIMITATIONS

Twelve patients were treated-three in cohorts 1 and 2 and six in cohort 3. No pain flares were noted. One patient came off study because of epidural disease, which was treated with radiation. Average testosterone levels were within normal limits, although dihydrotestosterone (DHT) levels on average were supraphysiologic in cohort 3. One patient achieved a PSA decline of >50% from baseline. No objective responses were seen. For cohort 3, median time on treatment was 84 d (range: 23-247 d).

CONCLUSIONS

We have demonstrated that patients with CRMPC can be safely treated in clinical trials using high-dose exogenous testosterone. Patients did not, on average, achieve sustained supraphysiologic serum testosterone levels. Future studies should employ strategies to maximize testosterone serum levels, use contemporary methods of identifying patients with androgen receptor overexpression, and utilize PSA Working Group II Consensus Criteria clinical trial end points.

TRIAL REGISTRATION

ClinicalTrials.gov; NCT00006044.

Phase I study of samarium-153 lexidronam with docetaxel in castration-resistant metastatic prostate cancer

PURPOSE

Early studies of patients with castration-resistant metastatic prostate cancer (CRMPC) suggest that chemotherapy administered with a dose of a bone-seeking radiopharmaceutical is superior to chemotherapy alone. To build on this strategy and fully integrate a repetitively dosed bone-seeking radiopharmaceutical into a contemporary chemotherapy regimen, we conducted a phase I study of docetaxel and samarium-153 ((153)Sm) lexidronam.

PATIENTS AND METHODS

Men with progressive CRMPC were eligible. Cohorts of three to six patients were defined by dose escalations as follows: docetaxel 65, 70, 75, 75, 75 mg/m(2) and (153)Sm ethylenediaminetetramethylenephosphonate (EDTMP) 0.5, 0.5, 0.5, 0.75, 1 mCi/kg. Each cycle lasted a minimum of 6 (cohorts 1 through 5) or 9 (cohort 6) weeks. Docetaxel was administered on days 1 and 22 (and day 43 for cohort 6), and (153)Sm-EDTMP was administered on day -1 to 1 of each cycle. Patients with acceptable hematologic toxicities were eligible to receive additional cycles until progression.

RESULTS

Twenty-eight men were treated in six cohorts. Maximum-tolerated dose was not reached, because full doses of both agents were well tolerated, even using an every-6-week dosing schedule of (153)Sm-EDTMP. Patients received an average of 5.6 docetaxel doses (range, one to 13 doses) and 2.9 (153)Sm-EDTMP doses (range, one to six doses). Fifteen patients demonstrated a more than 50% decline in prostate-specific antigen. Treatment significantly reduced indices of bone deposition and resorption.

CONCLUSION

Docetaxel and (153)Sm-EDTMP can be combined safely at full doses over repeated cycles. Responses were seen in the small group of patients with taxane-resistant disease tested. The optimal phase II doses for patients with taxane-naïve disease may differ from those optimal for patients with taxane-resistant disease.

Phase II trial of docetaxel with rapid androgen cycling for progressive noncastrate prostate cancer

PURPOSE

We evaluated rapid androgen cycling in combination with docetaxel for men with progressive noncastrate prostate cancers.

PATIENTS AND METHODS

Noncastrate patients with 150 ng/dL) and an undetectable prostate-specific antigen (PSA;

RESULTS

A higher proportion of patients achieved the undetectable PSA outcome at 18 months in cohort 2 relative to cohort 1 (13% v 0%). The 16% incidence of febrile neutropenia was higher than that observed in patients was castration-resistant disease, which may have been related to a 50% reduction in overall docetaxel clearance in the noncastrate group. There was no alteration in CYP3A4 activity (P = .87) or docetaxel clearance (P = .88) between cycles.

CONCLUSION

The undetectable PSA end point allows for a rapid screening of interventions for further study. Increasing the number of docetaxel cycles after a shorter period of testosterone repletion, and a longer duration of testosterone depletion, increased the proportion of men who achieved an undetectable PSA. The higher-than-expected incidence of febrile neutropenia may have been related to the reduced overall docetaxel clearance in patients with noncastrate versus castrate testosterone levels.

Collapse

Key Words Collapse

MESH Headings

• Adult
• Aged
• Aged, 80 and over
• Antineoplastic Combined Chemotherapy Protocols/administration & dosage
• Cytochrome P-450 CYP3A
• Cytochrome P-450 Enzyme System/metabolism
• Docetaxel
• Humans
• Leuprolide/administration & dosage
• Male
• Middle Aged
• Prostate-Specific Antigen/blood
• Prostatic Neoplasms/drug therapy
• Prostatic Neoplasms/metabolism
• Taxoids/administration & dosage
• Taxoids/pharmacokinetics
• Testosterone/administration & dosage
• Testosterone/metabolism

Collapse

Grants

• P30 CA006973-48 NCI NIH HHS
• P30 CA006973 NCI NIH HHS
• P50-CA92629 NCI NIH HHS
• P50 CA092629 NCI NIH HHS
• PC051382 NCI NIH HHS

Collapse

Affiliation(s)

Dana Rathkopf Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York, USA and Department of Medicine, Joan and Sanford Weill College of Medicine, New York, New York, USA
Michael A. Carducci Prostate Cancer Program, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
Michael J. Morris Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York, USA and Department of Medicine, Joan and Sanford Weill College of Medicine, New York, New York, USA
Susan F. Slovin Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York, USA and Department of Medicine, Joan and Sanford Weill College of Medicine, New York, New York, USA
Mario A. Eisenberger Prostate Cancer Program, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
Roberto Pili Prostate Cancer Program, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
Samuel R. Denmeade Prostate Cancer Program, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
Moshe Kelsen Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York, USA and Department of Medicine, Joan and Sanford Weill College of Medicine, New York, New York, USA
Tracy Curley Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York, USA and Department of Medicine, Joan and Sanford Weill College of Medicine, New York, New York, USA
Regina Priet Prostate Cancer Program, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
Connie Collins Prostate Cancer Program, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
Martin Fleisher Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
Glenn Heller Department of Clinical Chemistry, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
Sharyn D. Baker Pharmaceutical Sciences Department, St. Jude Children’s Research Hospital, Memphis, TN, USA
Howard I. Scher Genitourinary Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York, USA and Department of Medicine, Joan and Sanford Weill College of Medicine, New York, New York, USA

Collapse

Phase I trial of 17-allylamino-17-demethoxygeldanamycin in patients with advanced cancer

PURPOSE

To define the maximum tolerated dose (MTD), toxicities, and pharmacokinetics of 17-allylamino-17-demethoxygeldanamycin (17-AAG) when administered using continuous and intermittent dosing schedules.

EXPERIMENTAL DESIGN

Patients with progressive solid tumor malignancies were treated with 17-AAG using an accelerated titration dose escalation schema. The starting dose and schedule were 5 mg/m(2) daily for 5 days with cycles repeated every 21 days. Dosing modifications based on safety, pharmacodynamic modeling, and clinical outcomes led to the evaluation of the following schedules: daily x 3 repeated every 14 days; twice weekly (days 1, 4, 8, and 11) for 2 weeks every 3 weeks; and twice weekly (days 1 and 4) without interruption. During cycle 1, blood was collected for pharmacokinetic and pharmacodynamic studies.

RESULTS

Fifty-four eligible patients were treated. The MTD was schedule dependent: 56 mg/m(2) on the daily x 5 schedule; 112 mg/m(2) on the daily x 3 schedule; and 220 mg/m(2) on the days 1, 4, 8, and 11 every-21-day schedule. Continuous twice-weekly dosing was deemed too toxic because of delayed hepatotoxicity. Hepatic toxicity was also dose limiting with the daily x 5 schedule. Other common toxicities encountered were fatigue, myalgias, and nausea. This latter adverse effect may have been attributable, in part, to the DMSO-based formulation. Concentrations of 17-AAG above those required for activity in preclinical models could be safely achieved in plasma. Induction of a heat shock response and down-regulation of Akt and Raf-1 were observed in biomarker studies.

CONCLUSION

The MTD and toxicity profile of 17-AAG were schedule dependent. Intermittent dosing schedules were less toxic and are recommended for future phase II studies.

Rapid androgen cycling as treatment for patients with prostate cancer

PURPOSE

To investigate the safety and feasibility of rapid androgen cycling for men with progressive prostate cancer.

EXPERIMENTAL DESIGN

Schedule 1 included a 4-week induction of androgen depletion, followed by 4-week treatment cycles of a monthly gonadotropin-releasing hormone agonist, testosterone on days 1 to 7, and an estrogen patch on days 8 to 21. Schedule 2 included a 12-week induction of androgen depletion followed by 4-week cycles of gonadotropin-releasing hormone agonist and testosterone, but no estrogens for patients with a prostate-specific antigen (PSA) nadir <1 ng/mL after induction. The primary end point was serially declining PSA trough values over six treatment cycles.

RESULTS

Thirty-six patients were treated; 27 were evaluable after cycling, of whom 8 of 12 (67%) and 9 of 15 (60%) on schedules 1 and 2, respectively, reached the end point. Five patients with PSA >1 ng/mL following induction did not cycle. No patient progressed radiographically or clinically during cycling. Three posttherapy PSA patterns were observed: a decline followed by a rapid increase in trough levels, a sustained decline with a plateau at a detectable nadir, and a decline to an undetectable nadir. Mean testosterone levels were castrate at the time of trough and in the normal physiologic range following androgen repletion. Major toxicities included grades 1 and 2 fatigue, hepatitis, gynecomastia, and hot flashes.

CONCLUSIONS

Rapid hormonal cycling is feasible and well tolerated, and successive declines in PSA troughs are achievable. Although the sample size was small, the proportion of patients achieving declining PSA at the end of six cycles was comparable with that reached with continuous androgen depletion therapy.

Phase I trial results of PCK3145 in patients (pts) with castrate metastatic prostate cancer (PC)—The US experience

4650

Background: PCK3145 is a synthetic 15-mer peptide derived from the natural sequence of amino acids of Prostate Secretory Protein (PSCP94), a predominant protein found in seminal fluid. Its expression in PC is down-regulated in pts with metastatic disease and is believed to be a signal transduction inhibitor via multiple pathways in carcinogenesis. Recent data from a phase IIa trial in Great Britain demonstrated safety and suggested reduction in MMP-9 levels, an enzyme involved in angiogenesis, tumor invasion and metastasis. A phase I trial was performed to assess dosing and dosing schedule, pharmacokinetics, safety and impact on MMP-9 levels in pts with castrate metastatic PC who have failed multiple therapies including hormones and chemotherapy. Methods: Two cohorts of 10 pts received either 7.5 mg/m2 twice weekly or 15 mg/m2 weekly, respectively. Pts were treated for 4 weeks followed by a 2 week non-treatment period. Pts could receive addtional two-month cycles if PSAs and scans remained stable. MMP-9 levels, PSA, pharmacokinetics and imaging assessments were done at screening, and at weeks 2, 4 and 6. Results: Ten pts have been enrolled at each dose level. No adverse events were observed, however, declines in MMP-9 levels occurred in most pts by week #3 posttreatment. MMP-9 levels rose when drug was discontinued. Six pts were taken off study due to disease progression whereas 5 pts were discontinued due to rising PSAs. One pt at the 7.5 mg/m2 biweekly dosing schedule received 4 additional cycles with stable PSAs and scans with a PSA doubling time which increased from 4 months pretreatment to 8 months posttreatment. Conclusions: PCK3145 was well-tolerated without toxicity. While early, the weekly dosing schedule appears to result in greater declines in MMP-9 levels and will likely be used in a forthcoming phase II trial in chemotherapy naive pts.

[Table: see text]

Pilot trial of unlabeled and indium-111-labeled anti-prostate-specific membrane antigen antibody J591 for castrate metastatic prostate cancer

BACKGROUND

Prostate-specific membrane antigen (PSMA) is a transmembrane glycoprotein primarily expressed on benign and malignant prostatic epithelial cells. J591 is an IgG1 monoclonal antibody that targets the external domain of the PSMA. The relationship among dose, safety, pharmacokinetics, and antibody-dependent cellular cytotoxicity (ADCC) activation for unlabeled J591 has not been explored.

PATIENTS AND METHODS

Patients with progressive metastatic prostate cancer despite androgen deprivation were eligible. Each patient received 10, 25, 50, and 100 mg of J591. Two milligrams of antibody, conjugated with the chelate 1,4,7,10-tetraazacyclododecane-N, N',N'',N'''-tetraacetic acid, were labeled with 5 mCi indium-111 (111In) as a tracer. One group of patients received unlabeled J591 before the labeled antibody; the other received both together. Toxicities, pharmacokinetic properties, biodistribution, ADCC induction, immunogenicity, and clinical antitumor effects were assessed.

RESULTS

Fourteen patients were treated (seven in each group). Treatment was well tolerated. Biodistribution of 111In-labeled J591 was comparable in both groups. The mean T1/2 was .96, 1.9, 2.75, and 3.47 days for the 10, 25, 50, and 100 mg doses, respectively. Selective targeting of 111In-labeled J591 to tumor was seen. Hepatic saturation occurred by the 25-mg dose. ADCC activity was proportional to dose. One patient showed a >50% prostate-specific antigen decline.

CONCLUSIONS

J591 is well tolerated in repetitive dose-escalating administrations. The rate of serum clearance decreases with increasing antibody mass. ADCC activation is proportional to antibody mass. The optimal dose is 25 mg for radioimmunotherapy and 100 mg for immunotherapy. Phase II studies using J591 as a radioconjugate are under way.

Potential Role of Histone Deacetylase Inhibitors in Mesothelioma: Clinical Experience with Suberoylanilide Hydroxamic Acid

BACKGROUND

Histone deacetylase inhibitors are a novel class of therapeutic agents that inhibit deacetylate histones and other proteins involved in the regulation of gene expression and cell cycle progression. Phase I trials of intravenous and oral formulations of one such agent, vorinostat (suberoylanilide hydroxamic acid [SAHA]), have shown that it is safe and tolerable, that it inhibits histone deacetylation in peripheral blood mononuclear cells, and that it has a broad range of antitumor activity.

PATIENTS AND METHODS

Thirteen patients with mesothelioma were included in a phase I trial of oral SAHA. All but one had previously been treated with chemotherapy.

RESULTS

Four patients completed > or = 6 cycles of therapy; 2 patients demonstrated a partial response. The toxicities in this cohort of patients were similar to those observed in the entire phase I trial: primarily fatigue, dehydration, nausea, and vomiting.

CONCLUSION

Given the dearth of treatment options for patients with advanced mesothelioma who have progressed after first-line chemotherapy, these results are encouraging. A placebo-controlled, randomized phase III study of oral SAHA is now open for patients with mesothelioma in whom treatment with pemetrexed has failed.

Phase I study of an oral histone deacetylase inhibitor, suberoylanilide hydroxamic acid, in patients with advanced cancer

PURPOSE

To determine the safety, dosing schedules, pharmacokinetic profile, and biologic effect of orally administered histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) in patients with advanced cancer.

PATIENTS AND METHODS

Patients with solid and hematologic malignancies were treated with oral SAHA administered once or twice a day on a continuous basis or twice daily for 3 consecutive days per week. Pharmacokinetic profile and bioavailibity of oral SAHA were determined. Western blots and enzyme-linked immunosorbent assays of histones isolated from peripheral-blood mononuclear cells (PBMNCs) pre and post-therapy were performed to evaluate target inhibition.

RESULTS

Seventy-three patients were treated with oral SAHA and major dose-limiting toxicities were anorexia, dehydration, diarrhea, and fatigue. The maximum tolerated dose was 400 mg qd and 200 mg bid for continuous daily dosing and 300 mg bid for 3 consecutive days per week dosing. Oral SAHA had linear pharmacokinetics from 200 to 600 mg, with an apparent half-life ranging from 91 to 127 minutes and 43% oral bioavailability. Histones isolated from PBMNCs showed consistent accumulation of acetylated histones post-therapy, and enzyme-linked immunosorbent assay demonstrated a trend towards a dose-dependent accumulation of acetylated histones from 200 to 600 mg of oral SAHA. There was one complete response, three partial responses, two unconfirmed partial responses, and 22 (30%) patients remained on study for 4 to 37+ months.

CONCLUSIONS

Oral SAHA has linear pharmacokinetics and good bioavailability, inhibits histone deacetylase activity in PBMNCs, can be safely administered chronically, and has a broad range of antitumor activity.

Multi-institutional randomized phase II trial of the epothilone B analog ixabepilone (BMS-247550) with or without estramustine phosphate in patients with progressive castrate metastatic prostate cancer

PURPOSE

To evaluate the antitumor activity and safety of the epothilone B analog, ixabepilone, with or without estramustine phosphate (EMP), in chemotherapy-naive patients with progressive castrate metastatic prostate cancer.

PATIENTS AND METHODS

Patients were randomly assigned to receive ixabepilone (35 mg/m(2)) by intravenous infusion every 3 weeks with or without EMP 280 mg orally three times daily on days 1 to 5.

RESULTS

Between December 2001 and October 2003, 92 patients were enrolled and randomly assigned to treatment with ixabepilone alone (45 patients) or in combination with EMP (47 patients). Grades 3 and 4 toxicities experienced by more than 5% of patients included neutropenia (22%), fatigue (9%), and neuropathy (13%) on the ixabepilone arm, and neutropenia (29%), febrile neutropenia (9%), fatigue (9%), neuropathy (7%), and thrombosis (6%) on the ixabepilone + EMP arm. Post-treatment declines in prostate-specific antigen of > or = 50% were achieved in 21 of 44 patients (48%; 95% CI, 33% to 64%) on the ixabepilone arm, and 31 of 45 patients (69%; 95% CI, 55% to 82%) on the ixabepilone + EMP arm. In patients with measurable disease, partial responses were observed in eight of 25 patients (32%; 95% CI, 14% to 50%) on the ixabepilone arm, and 11 of 23 (48%; 95% CI, 27% to 68%) on the ixabepilone + EMP arm. Time to prostate-specific antigen progression was 4.4 months (95% CI, 3.1 to 6.9 months) on the ixabepilone-alone arm and 5.2 months (95% CI, 4.5 to 6.8 months) on the combination arm.

CONCLUSION

Ixabepilone, with or without estramustine phosphate, is well tolerated and has antitumor activity in patients with castrate metastatic prostate cancer.

High-dose calcitriol, zoledronate, and dexamethasone for the treatment of progressive prostate carcinoma

BACKGROUND

Preclinical and clinical data have suggested that high-dose calcitriol (1,25-dihydroxycholecalciferol) has activity against prostate carcinoma. Pulse-dosed calcitriol and dexamethasone may maximize tolerability and efficacy. The authors examined the toxicity of pulse-dosed calcitriol with zoledronate and with the addition of dexamethasone at the time of disease progression.

METHODS

Patients with progressive prostate carcinoma were eligible for the current study. In cohorts of 3-6 patients, calcitriol was administered for 3 consecutive days per week, starting at a dose of 4 microg per day. Doses were escalated to 30 microg per day. Intravenous zoledronate (4 mg) was administered monthly. Dexamethasone could be added to the regimen at disease progression. Toxicities, markers of bone turnover, plasma calcitriol levels, and clinical outcomes were recorded.

RESULTS

Thirty-one patients were treated in cohorts that were defined by the calcitriol dose administered (4, 6, 8, 10, 14, 20, 24, or 30 microg). Seven patients received dexamethasone. Three patients had their doses reduced due to calcium-related laboratory findings. Patients tolerated therapy well, even in the 30 microg cohort; therefore, a maximum tolerated dose was not defined. Peak plasma levels observed in the 24 microg and 30 microg cohorts ranged from 391 to 968 pg/mL. Minimal antitumor effects were observed.

CONCLUSIONS

Calcitriol was well tolerated at doses up to and including 30 microg 3 times per week in combination with intravenous zoledronate 4 mg monthly, with or without dexamethasone, in patients with progressive prostate carcinoma. Peak plasma levels in the 24 microg and 30 microg cohorts were greater than the levels associated with antitumor effects preclinically. Due to the cumbersome dosing schedule and the lack of significant activity observed, Phase II trials of this regimen are not planned.

Clinical experience with intravenous estramustine phosphate, paclitaxel, and carboplatin in patients with castrate, metastatic prostate adenocarcinoma

BACKGROUND

The combination of paclitaxel, oral estramustine phosphate (EMP), and carboplatin (TEC) has shown antitumor activity in patients with castrate, metastatic prostate carcinoma. To improve the therapeutic efficacy and reduce the toxicity of TEC, the authors substituted intravenous (i.v.) EMP for oral EMP based on single-agent studies demonstrating an improved safety profile with i.v. EMP.

METHODS

Patients with progressive, castrate, metastatic prostate carcinoma were treated with up to 6 4-week cycles of i.v. EMP (500-1500 mg/m(2) per week), paclitaxel (100 mg/m(2) per week), and carboplatin (target area under the curve = 6 mg/mL every 4 weeks).

RESULTS

Thirty patients were treated in 6 dose cohorts. Deep venous thrombosis occurred in 5 of 30 patients (17%). Other common Grade 3/4 (according to National Cancer Institute Common Toxicity Criteria) toxicities included hepatic toxicity (23%) and leukopenia (24%). Posttherapy prostate specific antigen declines > 50% were seen in 18 of 30 patients (60%), and declines > 80% were seen in 15 of 30 patients (50%). Eleven of 17 patients (65%) with measurable soft tissue disease achieved a partial response. Four of 27 patients (15%) with osseous metastases demonstrated improvement on bone scan.

CONCLUSIONS

Intravenous EMP was administered safely with paclitaxel and carboplatin and produced clinical outcomes similar to the outcomes achieved with the TEC regimen. Substitution of i.v. EMP for the oral formulation was found to result in a lower incidence of severe nausea but increased hepatic toxicity.

Phase I clinical trial of histone deacetylase inhibitor: suberoylanilide hydroxamic acid administered intravenously

PURPOSE

To evaluate the safety, pharmacokinetics, and biological activity of suberoylanilide hydroxamic acid (SAHA) administered by 2-h i.v. infusion in patients with advanced cancer.

EXPERIMENTAL DESIGN

SAHA was administered for 3 days every 21 days in part A and 5 days for 1-3 weeks in part B. Dose escalation proceeded independently in patients with solid tumor and hematological malignancies (part B only). Pharmacokinetic studies were performed along with assessment of acetylated histones in peripheral blood mononuclear cells and tumor tissues.

RESULTS

No dose-limiting toxicities were observed in 8 patients enrolled in part A (75, 150, 300, 600, and 900 mg/m(2)/day). Among 12 hematological and 17 solid tumor patients enrolled in part B (300, 600, and 900 mg/m(2)/day), therapy was delayed > or = 1 week for grade 3/4 leukopenia and/or thrombocytopenia in 2 of 5 hematological patients at 600 mg/m(2)/day x 5 days for 3 weeks. The maximal-tolerated dose was 300 mg/m(2)/day x 5 days for 3 weeks for hematological patients. One solid patient on 900 mg/m(2)/day x 5 days for 3 weeks developed acute respiratory distress and grade 3 hypotension. The cohort was expanded to 6 patients, and no additional dose-limiting toxicities were observed. Mean terminal half-life ranged from 21 to 58 min, and there was dose-proportional increase in area under the curve. An accumulation of acetylated histones in peripheral blood mononuclear cells up to 4 h postinfusion was observed at higher dose levels. Posttherapy tumor biopsies showed an accumulation of acetylated histones by immunohistochemistry. Four (2 lymphoma and 2 bladder) patients had objective tumor regression with clinical improvement in tumor related symptoms.

CONCLUSIONS

Daily i.v. SAHA is well tolerated, inhibits the biological target in vivo, and has antitumor activity in solid and hematological tumors.

Estimating survival benefit in castrate metastatic prostate cancer: decision making in proceeding to a definitive phase III trial

OBJECTIVES

In designing a Phase II trial, the acceptable clinical activity region for a new therapy is often developed using data from historically treated patients. This region incorrectly ignores the variability of this estimate, because the efficacy of the prior treatment lies somewhere around the estimate. The size of this interval is dependent on the sample size used. This report illustrates the use of a published method that accounts for this uncertainty and aids in the decision to proceed to a definitive trial.

METHODS

A historical data set of low-risk patients with progressive castrate metastatic prostate cancer and a group of similar patients treated in a Phase II chemotherapy trial were used. The 1-year Kaplan-Meier estimate of survival was obtained for both. This approach uses the 75% upper confidence bound of the 1-year survival probability from the historical data set to define the lower limit of acceptable clinical activity. Use of this bound makes the approach more conservative, and hence the decision to proceed to a Phase III trial more difficult.

RESULTS

In the low-risk historical patients, the 1-year Kaplan-Meier estimate of survival was 66.4% (75% upper confidence bound 71.0%). In the Phase II patients, the 1-year Kaplan-Meier estimate of survival was 89.5% (95% lower confidence bound 78.2%).

CONCLUSIONS

A hypothesis test using the 75% upper confidence bound to define the lower limit of acceptable clinical activity demonstrates that the 1-year survival probability on Taxol/estramustine/carboplatin is greater than that of the historical population, and hence should be taken into a definitive trial. The design provides investigators increased confidence in making this decision.

Paclitaxel, estramustine phosphate, and carboplatin in patients with advanced prostate cancer

PURPOSE

To determine the safety and activity of weekly paclitaxel in combination with estramustine and carboplatin (TEC) in patients with advanced prostate cancer.

PATIENTS AND METHODS

In a dose-escalation study, patients with advanced prostate cancer were administered paclitaxel (weekly 1-hour infusions of 60 to 100 mg/m(2)), oral estramustine (10 mg/kg), and carboplatin (area under the curve, 6 mg/mL-min every 4 weeks). Paclitaxel levels were determined 0, 30, 60, 90, and 120 minutes and 18 hours after infusion, and a concentration-time curve was estimated. Once a safe dose was established, a multi-institutional phase II trial was conducted in patients with progressive androgen-independent disease.

RESULTS

Fifty-six patients with progressive androgen-independent disease were treated for a median of four cycles. The dose of paclitaxel was escalated from 60 to 100 mg/m(2) without the occurrence of DLT. Posttherapy decreases in serum prostate-specific antigen levels of 50%, 80%, and 90% were seen in 67%, 48%, and 39% (95% confidence interval, 55% to 79%, 35% to 61%, 26% to 52%) of the patients, respectively. Of the 33 patients with measurable disease, two (6%) had a complete response and 13 (39%) had a partial response. The overall median time to progression was 21 weeks, and the median survival time for all patients was 19.9 months. Major grade 3 or 4 adverse effects were thromboembolic disease (in 25% of patients), hyperglycemia (in 38%), and hypophosphatemia (in 42%). Significant leukopenia, thrombocytopenia, and peripheral neuropathy were not observed.

CONCLUSION

TEC has significant antitumor activity and is well tolerated in patients with progressive androgen-independent prostate cancer.

The development of biologic end points in patients treated with differentiation agents: an experience of retinoids in prostate cancer

The evaluation of new therapies in prostate cancer requires unique end points for agents with diverse mechanisms of action. Because retinoic acid may have a confounding effect on prostate-specific antigen, we incorporated a pathological end point into the outcome assessment of two sequential clinical trials using all-trans-retinoic acid (ATRA) and the combination of 13-cis-retinoic acid and IFN-2a (cRA¿IFN). Pre- and posttherapy tumor biopsy specimens were studied for histological changes, apoptosis (terminal deoxynucleotidyl transferase-mediated nick end labeling assay), and proliferation index (Ki67). Prostate-specific membrane antigen (PSMA) expression was also evaluated using two different monoclonal antibodies to its intracellular domain (Cytogen 7E11 and Hybritech PM2). Fourteen patients with androgen-independent disease were treated with ATRA (50 mg/m2 p.o. every 8 h daily) and 16 androgen-independent and 4 androgen-dependent patients were treated with cRA¿IFN (10 mg/kg/day cRA plus 3, 6, or 9 million units daily IFN). Both therapies were well tolerated, with fatigue and cheilitis being the most common adverse events. Clinical activity, assessed by radiographs and serum prostate-specific antigen, was minimal, and the majority of patients progressed within 3 months. One patient with androgen-dependent disease had prolonged stabilization for >1 year. The majority of cases (95%) showed no gross histological changes and no difference in apoptotic or proliferative indices. Increased PSMA immunoreactivity was seen in seven of nine (78%) cases using PM2 antibody and in two of nine (22%) cases using the 7E11 antibody. Although antitumor effects were modest, the results suggest a role for retinoids in modulating the expression of PSMA on prostate cancer cells.

Rhenium-186-labeled hydroxyethylidene diphosphonate dosimetry and dosing guidelines for the palliation of skeletal metastases from androgen-independent prostate cancer

Rhenium-186 (tin)-labeled hydroxyethylidene diphosphonate (186Re-labeled HEDP) was evaluated in 27 men with progressive androgen-independent prostate cancer and bone metastases. Administered activities ranged from 1251 to 4336 MBq (33.8-117.2 mCi). The primary objectives were to assess tumor targeting, normal organ dosimetry, and safety. Antitumor effects were assessed by posttherapy changes in prostate-specific antigen and, when present, palliation of pain. Whole-body kinetics, blood and kidney clearance, skeletal dose, marrow dose, and urinary excretion of the isotope were assessed. Targeting of skeletal disease was observed over the period of quantification (4-168 h). Radiation doses to whole body, bladder, and kidney were well tolerated. The dose-limiting toxicity was myelosuppression (grade III) at 4107 MBq (111 mCi) and grade II at 296 MBq (80 mCi). Probe clearance (whole body) and urinary excretion measurements were highly correlated. Of the six patients treated at the highest dosage schedules (three at 1510 MBq/m2 and three at 1665 MBq/m2), three showed a posttherapy decline in prostate-specific antigen of 50% or more. The declines were not sustained. The determination of total activity retained at 24 h, as well as an estimate of marrow dose, correlated with the amount of myelosuppression observed. These results suggest that a single 24-h measurement of retained activity would allow individualized dosing and an improved therapeutic index relative to fixed dosing schema. Repetitive dosing is required to increase palliation.

Prospective evaluation of hydrocortisone and suramin in patients with androgen-independent prostate cancer

PURPOSE

To assess efficacy of intermittent infusion of suramin in patients with androgen-independent prostate cancer who have had disease progression on hydrocortisone.

PATIENTS AND METHODS

Chemotherapy-naive patients with progressive androgen-independent prostate cancer were given hydrocortisone 40 mg/d and monitored for treatment effect. At the time of disease progression, suramin was administered on a pharmacokinetically derived, 2-week dosing schedule.

RESULTS

Thirty patients with a median Karnofsky performance status (KPS) of 90% were treated with hydrocortisone. No responses were seen in 12 patients with measurable disease or 29 patients with abnormal bone scans. Thirty patients had an increasing prostate-specific antigen (PSA) level before treatment and six (20%) had a more than 50% decline in PSA from the baseline value for a median of 16 weeks (range, 12 to 52+). Twenty-eight patients had disease progression after a median of 7 weeks (range, 3 to 23), and two patients have continued to receive hydrocortisone for 44 and 52 weeks. Twenty-eight patients received hydrocortisone and suramin, with median suramin concentrations of 97 to 170 micrograms/mL for 4 weeks. No responses in measurable disease and no improvements in bone scans were seen. Five patients (18%) showed a more than 50% decline in PSA levels from baseline, of whom three had previously responded to hydrocortisone. Only two of 24 patients who did not show a posttherapy decline in PSA levels after hydrocortisone had a reduction in PSA levels with the addition of suramin. Toxicity profiles were acceptable with each agent, although a higher proportion of subjects showed hematologic, cardiac, and neurologic events when suramin was added.

CONCLUSION

Suramin has limited efficacy in patients with androgen-independent prostate cancer who have had disease progression after hydrocortisone.

Suramin and hydrocortisone: determining drug efficacy in androgen-independent prostate cancer

PURPOSE

The combination of suramin and hydrocortisone has shown clinical benefit in patients with androgen-independent prostate cancer. Widespread use was limited by the complex dose schedules and the need for pharmacologic monitoring. This study reports three sequential pharmacokinetically derived treatment regimens that simplified the administration of suramin and hydrocortisone with reduced toxicity.

PATIENTS AND METHODS

Three cohorts of patients with advanced prostate cancer that progressed despite castrate levels of testosterone received oral hydrocortisone plus suramin administered in the following manners: (1) a loading dose of suramin followed by a continuous infusion using an adaptive control program (cohort A); (2) an intermittent schedule using a simplified adaptive control schedule (cohort B); and (3) an empiric dosing regimen (cohort C). Drug concentrations were monitored along with the toxicities associated with each regimen. Efficacy was assessed using measurable-disease criteria, radionuclide scans, and posttherapy changes in prostate-specific antigen (PSA) levels.

RESULTS

Fifty-six patients were treated and plasma suramin concentrations were similar for each regimen. A partial response was observed in 4% (one of 28; 95% confidence interval, 0% to 18.4%) of patients with measurable disease, while 12% (six of 50; 95% confidence interval, 4.5% to 24.3%) had a greater than 80% decline in the baseline PSA level. The median duration of response was 12 months. No responses on radionuclide scans were seen. Anemia and lymphocytopenia were the most common toxicities, while 7% of patients developed a sensory or motor neurotoxicity. In the sequential regimens, the frequency of renal insufficiency (P = .04) and coagulopathy (P < .0001) decreased, while transaminase elevations (P = .05) were more common using intermittent infusions (cohorts B and C) versus continuous infusion schedules (cohort A).

CONCLUSION

The administration of suramin was simplified and the drug concentrations were maintained. In this cohort of patients with advanced prostate cancer, the clinical activity of suramin using these dosing schedules was limited. Pharmacodynamic issues, patients selection, and criteria to assess efficacy could have effected the clinical outcome.

Detection of circulating tumor cells in patients with localized and metastatic prostatic carcinoma: clinical implications

PURPOSE

To determine the frequency with which prostate-specific antigen (PSA)-positive cells can be detected in the peripheral blood of patients with prostatic cancer in different stages and with different sensitivities to hormonal therapy.

PATIENTS AND METHODS

Peripheral blood from 107 men with prostatic cancer and 27 non-prostate cancer controls was analyzed for PSA mRNA using reverse-transcriptase polymerase chain reaction (RT-PCR) and Southern blotting.

RESULTS

The lower limit of detection was one PSA-producing cell diluted into 1 x 10(6) blood mononuclear cells. The test detected PSA mRNA in four of 25 patients (16%) with clinically organ-confined (T1-2) disease, three of 10 (30%) with T3-4 or N+ tumors, and 25 of 72 (35%) with distant metastases. None of the control samples were positive. An increase in positivity was observed with increasing PSA levels. Within the subgroup of patients with distant metastases, positivity was observed in six of 16 patients (38%) with normal or undetectable PSA levels after hormonal therapy and, overall, in 37% of patients (21 of 57) with androgen-independent disease.

CONCLUSION

An RT-PCR-based assay for PSA mRNA can detect circulating cells in the peripheral blood of patients with prostatic cancer. The frequency of positivity increases with tumor stage. A unique observation was the detection of cells in patients with no measurable PSA on hormonal therapy. This suggests that continued seeding of distant sites may still be occurring in these patients, despite seemingly successful therapy. The relationship between continued seeding, disease progression, and survival will require further study.

Effect of relative cumulative dose-intensity on survival of patients with urothelial cancer treated with M-VAC

PURPOSE

To evaluate the received dose-intensity in a mature data set of patients with advanced urothelial cancer who received at least one cycle of the methotrexate (M), vinblastine (V), Adriamycin ([A], doxorubicin; Adria Laboratories, Columbus, OH), and cisplatin (C) regimen (M-VAC).

PATIENTS AND METHODS

Received dose-intensity was evaluated over time by summing doses over cycles for each patient, cumulating treatment times, and assuming four cycles of chemotherapy were planned. Relative cumulative dose-intensity was then calculated for individual patients at the end of each cycle. To assess a relationship with survival, relative cumulative dose-intensity was then used as a time-dependent covariate in Cox regression.

RESULTS

The median follow-up was 6 years and median survival 13.3 months, with 20 patients alive at the time of analysis. Out of a maximum of 1.0, the median relative dose-intensity for the M-VAC combination decreased from .69 to .59 from cycle 1 to cycle 4. Similarly, a decrease from .68 to .62 and from .80 to .72 was observed for A and C, respectively. The median received dose-intensity for A was 6.0 mg/m2/wk, and for C 14 mg/m2/wk. Neither the four-cycle relative cumulative dose-intensity for the M-VAC combination, nor the relative cumulative dose-intensities for A or C were found to be significant prognostic factors.

CONCLUSION

The absence of an effect for received dose-intensity on survival may reflect the low dose-intensities of the components of the regimen actually delivered in this study. The results question whether the individual agents can be escalated sufficiently, with growth factor support, to improve significantly complete response proportions, a prerequisite for increasing the proportion of long-term survivors.

Dose-intensification of MVAC with recombinant granulocyte colony-stimulating factor as initial therapy in advanced urothelial cancer

PURPOSE

This study was undertaken to define an escalated dose schedule of methotrexate, vinblastine, doxorubicin, and cisplatin (E-MVAC) with hematopoietic growth-factor support, to define the ability to deliver E-MVAC with recombinant human granulocyte colony-stimulating factor (rhG-CSF) on 21- and 14-day schedules, and to assess the ability of rhG-CSF to maintain dose-intensity over four cycles of chemotherapy.

PATIENTS AND METHODS

Twenty-three patients with transitional-cell carcinoma of the urothelium received E-MVAC in a phase I investigation. Patients were treated on an every-21-day (n = 19) or every-14-day schedule of administration (n = 4), with rhG-CSF support. Delivered dose-intensity was calculated at the completion of four cycles of therapy relative to the planned administration of conventional MVAC (relative dose-intensity [RDI]). Peripheral-blood progenitor cell kinetics in these patients were studied prospectively.

RESULTS

Overall, the delivered RDI was 33% higher than the previously reported delivered dose-intensity of MVAC without hematopoietic support (140% for doxorubicin, 51% for cisplatin). Dose-intensity was well maintained through three cycles of therapy, after which leukopenia and thrombocytopenia became dose-limiting. Sixty-nine percent of patients with measurable disease responded, four (25%) with complete remissions. In five patients treated beyond the maximally tolerated dose (MTD), a 50- to 200-fold increase in G-CSF, granulocyte-macrophage CSF (GM-CSF), and interleukin-3 (IL-3)-responsive peripheral-blood progenitor cells over baseline was observed after 9 days of rhG-CSF administration.

CONCLUSION

These findings demonstrate the feasibility and limitations of dose intensification of M-VAC with rhG-CSF. While the overall impact of the increased drug administration can only be assessed in randomized comparisons, the results of the present trial suggest that escalations of the components of the four-drug regimen are unlikely to improve significantly the outcome for patients with advanced urothelial tract tumors.

Estramustine and vinblastine: use of prostate specific antigen as a clinical trial end point for hormone refractory prostatic cancer

The combination of estramustine phosphate and vinblastine sulfate, 2 agents with separate and unique antimicrotubular effects, has demonstrated additive cytotoxicity against the DU145 human prostate derived cell line in vitro. We evaluated this combination in 25 patients with progressive hormone refractory prostate cancer. Of 24 patients with an elevated prostate specific antigen (PSA) level at the start of treatment 13 (54%, 95% confidence limits 34 to 74%) had a greater than 50% decrease in PSA levels on at least 3 consecutive biweekly determinations. The median decrease in PSA in responding patients was 64% (mean 71.7%) and the median duration of response was 7 months. In 5 patients with bidimensionally measurable disease 2 partial responses were observed. Treatment was well tolerated, with mild and manageable toxicity. This is a well tolerated outpatient treatment regimen for patients with hormone-refractory prostatic cancer which deserves further investigation.

Therapeutic alternatives for hormone-refractory prostatic cancer

The currently available prognostic factors allow the identification of patients who are destined to do poorly with primary hormone therapy. Standardization of these factors is required so that they become incorporated into routine practice. For patients who relapse in osseous sites radiolabeled diphosphonates are one therapeutic alternative that can provide palliation. Future use will be directed to optimize treatment schedules, and use earlier in the course of the disease so that more durable palliation of bony metastases can be achieved. Evolving data on the use of PSA show that elevations antedate clinical relapse for most patients. In these cases, sequential changes can be used to assess therapeutic effects, which in turn can allow novel therapies to be screened more rapidly in the clinic. Criteria for the degree of change that is indicative of response must be standardized. Preliminary data suggest a 50% decline be the minimum that is used. The results with agents such as suramin, which interrupts autocrine and paracrine growth factor loops, are a therapeutic strategy that need further study. Future efforts will focus on defining which patients are best suited for specific therapeutic approaches.

Use of adaptive control with feedback to individualize suramin dosing

Suramin is the first putative growth factor inhibitor in clinical trial that has demonstrated antitumor activity. Administration of suramin is complicated by a narrow therapeutic index and significant interpatient variability of measured pharmacokinetic parameters. Because both antitumor response and dose-limiting toxicities are related to plasma suramin concentration profiles, individualized dose schedules are required for optimal administration of the compound. In this report, the use of optimal sampling theory to derive sparse data monitoring and control strategies for use with suramin is described. A fixed rate continuous infusion schedule was used in seven patients, and the time to peak concentration (280-300 micrograms/ml) ranged from 7.7-21 days (mean, 13.2 days) with a decline to 150 micrograms/ml in 3-22 days (mean, 11 days). An initial population pharmacokinetic model was fit using a maximum likelihood algorithm. The mean volume of the central compartment was 4.5 +/- 6.7 liters/m2, volume of the peripheral compartment 10.6 +/- 1.4 liters/m2, distributional half-life 25 +/- 5.4 h, and elimination half-life 29.7 +/- 6.9 h. The terminal half-life was shorter than previously reported. These parameters were used as the initial population model for an iterative 2-stage analysis. The resulting distributional half-life of 22.3 +/- 2.7 h and elimination half-life of 28.2 +/- 5.0 h were similar, reflecting the intensive sampling. The iterative 2-stage analysis model was then used to determine the optimal sampling times and to simulate 20 data sets for a protocol designed to maintain plasma concentrations in a defined concentration range. This strategy is currently under investigation in phase I clinical trials.

Trimetrexate in prostatic cancer: preliminary observations on the use of prostate-specific antigen and acid phosphatase as a marker in measurable hormone-refractory disease

Thirty-one patients with bidimensionally measurable hormone-refractory prostatic cancer received trimetrexate (TMTX). Serial values of prostate-specific antigen (PSA) and acid phosphatase (SAP) were correlated with response. Five patients (17%; 95% confidence interval, 3% to 30%) achieved a partial remission for a median of 3 months (range, 3 to 7.5 months). Marker levels showed large variations with no discernible patterns. Serial PSA and SAP in 19 patients with abnormal baseline values showed a correlation with measurable disease response in only 68% (13 of 19) and 47% (nine of 19) of patients, respectively. Values were then smoothed using an exploratory data analysis technique of running medians and averages. Trends in marker changes were much more apparent. Several "decision rules" were evaluated for use of markers as indices of disease progression. A 50% increase from the patient's minimum value in either PSA or SAP on two successive determinations correlated with progression in 90% of cases in this trial. TMTX has modest activity in prostatic cancer, and further trials are not warranted. Biochemical markers do not uniformly reflect disease activity in hormone-refractory disease, and changes in biochemical markers must be interpreted cautiously when used as the sole end point to assess efficacy in clinical trials.