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

Does castration status affect docetaxel-related adverse events? :Identification of risk factors for docetaxel-related adverse events in metastatic prostate cancer

BACKGROUND

Docetaxel-related adverse events (AEs) such as neutropenia and febrile neutropenia (FN) can be life-threatening. A previous in vivo study raised the hypothesis that the castration status affects the rate of hematologic AEs. We aimed to investigate the impact of castration status on the incidence of docetaxel-related AE in metastatic prostate cancer (mPCa) patients.

METHODS

We retrospectively analyzed the records of 265 mPCa patients treated with docetaxel, comprising 92 patients with metastatic hormone-sensitive prostate cancer (mHSPC) and 173 patients with metastatic castration-resistant prostate cancer (mCRPC) between January 2015 and December 2021. Common terminology Criteria for Adverse Events (CTCAE) was applied to evaluate AEs. We analyzed the differential incidences between mHSPC and mCRPC, and risk factors of hematologic and nonhematologic AEs using a logistic regression model.

RESULTS

The rate of patients who received primary prophylaxis against neutropenia was higher in those with the mHSPC compared with those with the mCRPC (7.5% vs. 33%, p < 0.001). Among the patients without primary prophylaxis, incidence rates of severe neutropenia (CTCAE ≥ Grade3) and FN were 89% and 16% in patients with mCRPC compared to 81% and 18% in those with mHSPC. Logistic regression analysis revealed that age ≥ 75 years and failure to provide primary prophylaxis were independent risk factors of severe neutropenia (odds ratio [OR]: 2.39, 95% confidential interval [CI]: 1.10-5.18 and OR: 15.8, 95% CI: 7.23-34.6, respectively). Eastern Cooperative Oncology Group Performance Status (ECOG-PS) ≧ 1 was an independent risk factor of FN (OR: 2.26, 95% CI: 1.13-4.54). Castration status (mHSPC vs. mCRPC) was not associated with the risks of severe neutropenia and FN.

CONCLUSIONS

Castration status did not affect the risk of severe neutropenia or FN in mPCa patients treated with docetaxel regardless of the disease state. Failure to provide primary prophylaxis and advanced patient age are independent risk factors of severe neutropenia; while patients with poor PS are more likely to develop FN. These findings may help guide the clinical decision-making for proper candidate selection of docetaxel treatment.

Should androgen deprivation therapy and other systemic treatments be used in men with prostate cancer and a rising PSA post-local treatments?

Biochemical recurrence is an evolving space in prostate cancer, with increasing multidisciplinary involvement. Androgen deprivation therapy has shown proof of its value in complementing salvage radiotherapy in high-risk biochemical relapsing patients; ongoing trials aim to further refine this treatment combination. As systemic treatments, and notably next-generation androgen receptor targeted agents, have moved towards early hormone-sensitive and non-metastatic stages, the prostate specific antigen (PSA)-relapse disease stage will be undoubtedly challenged by future evidence from such ongoing clinical trials. With the use of modern imaging and newer molecular technologies, including integration of tumoral genomic profiling and liquid biopsies in risk stratification, a path towards a precision oncology-focused approach will become a reality to guide in the future decisions for patients with a diagnosis of biochemical recurrence.

Cancer epithelia-derived mitochondrial DNA is a targetable initiator of a paracrine signaling loop that confers taxane resistance

The work provides a conceptual advance in functionally defining the cross talk of tumor epithelia with cancer-associated fibroblastic cells contributing to tumor progression and therapeutic resistance. Independent of protein-based signaling molecules, prostate cancer cells secreted mitochondrial DNA to induce associated fibroblasts to generate anaphylatoxin C3a to support tumor progression in a positive feedback loop. Interestingly, the standard of care chemotherapy, docetaxel, used to treat castrate-resistant prostate cancer was found to further potentiate this paracrine-signaling axis to mediate therapeutic resistance. Blocking anaphylatoxin C3a signaling cooperatively sensitized prostate cancer tumors to docetaxel. We reveal that docetaxel resistance is not a cancer cell-autonomous phenomena and that targeting an immune modulator derived from cancer-associated fibroblasts can limit the expansion of docetaxel-resistant tumors.

Stromal-epithelial interactions dictate cancer progression and therapeutic response. Prostate cancer (PCa) cells were identified to secrete greater concentration of mitochondrial DNA (mtDNA) compared to noncancer epithelia. Based on the recognized coevolution of cancer-associated fibroblasts (CAF) with tumor progression, we tested the role of cancer-derived mtDNA in a mechanism of paracrine signaling. We found that prostatic CAF expressed DEC205, which was not expressed by normal tissue-associated fibroblasts. DEC205 is a transmembrane protein that bound mtDNA and contributed to pattern recognition by Toll-like receptor 9 (TLR9). Complement C3 was the dominant gene targeted by TLR9-induced NF-κB signaling in CAF. The subsequent maturation complement C3 maturation to anaphylatoxin C3a was dependent on PCa epithelial inhibition of catalase in CAF. In a syngeneic tissue recombination model of PCa and associated fibroblast, the antagonism of the C3a receptor and the fibroblastic knockout of TLR9 similarly resulted in immune suppression with a significant reduction in tumor progression, compared to saline-treated tumors associated with wild-type prostatic fibroblasts. Interestingly, docetaxel, a common therapy for advanced PCa, further promoted mtDNA secretion in cultured epithelia, mice, and PCa patients. The antiapoptotic signaling downstream of anaphylatoxin C3a signaling in tumor cells contributed to docetaxel resistance. The inhibition of C3a receptor sensitized PCa epithelia to docetaxel in a synergistic manner. Tumor models of human PCa epithelia with CAF expanded similarly in mice in the presence or absence of docetaxel. The combination therapy of docetaxel and C3 receptor antagonist disrupted the mtDNA/C3a paracrine loop and restored docetaxel sensitivity.

Neutropenia and docetaxel exposure in metastatic castration-resistant prostate cancer patients: A meta-analysis and evaluation of a clinical cohort

The incidence of neutropenia in metastatic castration‐resistant prostate cancer (mCRPC) patients treated with docetaxel has been reported to be lower compared to patients with other solid tumors treated with a similar dose. It is suggested that this is due to increased clearance of docetaxel in mCRPC patients, resulting in decreased exposure. The aims of this study were to (1) determine if exposure in mCRPC patients is lower vs patients with other solid tumors by conducting a meta‐analysis, (2) evaluate the incidence of neutropenia in patients with mCRPC vs other solid tumors in a clinical cohort, and (3) discuss potential clinical consequences. A meta‐analysis was conducted of studies which reported areas under the plasma concentration‐time curves (AUCs) of docetaxel and variability. In addition, grade 3/4 neutropenia was evaluated using logistic regression in a cohort of patients treated with docetaxel. The meta‐analysis included 36 cohorts from 26 trials (n = 1150 patients), and showed that patients with mCRPC had a significantly lower mean AUC vs patients with other solid tumors (fold change [95% confidence interval (CI)]: 1.8 [1.5‐2.2]), with corresponding AUCs of 1.82 and 3.30 mg∙h/L, respectively. Logistic regression, including 812 patient, demonstrated that patients with mCRPC had a 2.2‐fold lower odds of developing grade 3/4 neutropenia compared to patients with other solid tumors (odds ratio [95%CI]: 0.46 [0.31‐0.90]). These findings indicate that mCRPC patients have a lower risk of experiencing severe neutropenia, possibly attributable to lower systemic exposure to docetaxel.

Drug development for noncastrate prostate cancer in a changed therapeutic landscape

The unprecedented progress in the treatment of metastatic castration-resistant prostate cancer is only beginning to be realized in patients with noncastrate disease. This slow progress in part reflects the use of trial objectives focused on time-to-event end points, such as time to metastasis and overall survival, which require long follow-up durations and large sample sizes, and has been further delayed by the use of approved therapies that are effective at the time of progression. Our central hypotheses are that progress can be accelerated, and that outcomes can be improved by shifting trial objectives to response measures occurring early that solely reflect the effects of the treatment. To test these hypotheses, a continuously enrolling multi-arm, multi-stage randomized trial design, analogous to that used in the STAMPEDE trial, has been developed. Eligibility is focused on patients with incurable disease or those with a high risk of death with any form of monotherapy alone. The primary objective is to eliminate all disease using a multimodality treatment strategy. End points include pathological complete response and an undetectable level of serum prostate-specific antigen, with recovery of serum testosterone levels. Both are binary, objective, and provide an early, quantitative indication of efficacy.

Deletion of tumor suppressors adenomatous polyposis coli and Smad4 in murine luminal epithelial cells causes invasive prostate cancer and loss of androgen receptor expression

Prostate cancer is the most diagnosed non-skin cancer in the US and kills approximately 27,000 men per year in the US. Additional genetic mouse models are needed that recapitulate the heterogeneous nature of human prostate cancer. The Wnt/beta-catenin signaling pathway is important for human prostate tumorigenesis and metastasis, and also drives tumorigenesis in mouse models. Loss of Smad4 has also been found in human prostate cancer and drives tumorigenesis and metastasis when coupled with other genetic aberrations in mouse models. In this work, we concurrently deleted Smad4 and the tumor suppressor and endogenous Wnt/beta-catenin inhibitor adenomatous polyposis coli (Apc) in luminal prostate cells in mice. This double conditional knockout model produced invasive castration-resistant prostate carcinoma with no evidence of metastasis. We observed mixed differentiation phenotypes, including basaloid and squamous differentiation. Interestingly, tumor cells in this model commonly lose androgen receptor expression. In addition, tumors disappear in these mice during androgen cycling (castration followed by testosterone reintroduction). These mice model non-metastatic castration resistant prostate cancer and should provide novel information for tumors that have genetic aberrations in the Wnt pathway or Smad4.

Exploiting Epigenetic Alterations in Prostate Cancer

Prostate cancer affects an increasing number of men worldwide and is a leading cause of cancer-associated deaths. Beside genetic mutations, many epigenetic alterations including DNA and histone modifications have been identified in clinical prostate tumor samples. They have been linked to aberrant activity of enzymes and reader proteins involved in these epigenetic processes, leading to the search for dedicated inhibitory compounds. In the wake of encouraging anti-tumor efficacy results in preclinical models, epigenetic modulators addressing different targets are now being tested in prostate cancer patients. In addition, the assessment of microRNAs as stratification biomarkers, and early clinical trials evaluating suppressor microRNAs as potential prostate cancer treatment are being discussed.

A Pilot Study of a Multimodal Treatment Paradigm to Accelerate Drug Evaluations in Early-stage Metastatic Prostate Cancer

OBJECTIVE

To evaluate a multimodal strategy aimed at treating all sites of disease that provides a rapid readout of success or failure in men presenting with non-castrate metastatic prostate cancers that are incurable with single modality therapy.

MATERIALS AND METHODS

Twenty selected men with oligometastatic M1a (extrapelvic nodal disease) or M1b (bone disease) at diagnosis were treated using a multimodal approach that included androgen deprivation, radical prostatectomy plus pelvic lymphadenectomy (retroperitoneal lymphadenectomy in the presence of clinically positive retroperitoneal nodes), and stereotactic body radiotherapy to osseous disease or the primary site. Outcomes of each treatment were assessed sequentially. Androgen deprivation was discontinued in responding patients. The primary end point was an undetectable prostate-specific antigen (PSA) after testosterone recovery. The goal was to eliminate all detectable disease.

RESULTS

Each treatment modality contributed to the outcome: 95% of the cohort achieved an undetectable PSA with multimodal treatment, including 25% of patients after androgen deprivation alone and an additional 50% and 20% after surgery and radiotherapy, respectively. Overall, 20% of patients (95% confidence interval: 3%-38%) achieved the primary end point, which persisted for 5, 6, 27+ , and 46+ months. All patients meeting the primary end point had been classified with M1b disease at presentation.

CONCLUSION

A sequentially applied multimodal treatment strategy can eliminate detectable disease in selected patients with metastatic spread at diagnosis. The end point of undetectable PSA after testosterone recovery should be considered when evaluating new approaches to rapidly set priorities for large-scale testing in early metastatic disease states and to shift the paradigm from palliation to cure.

Advances in hormonal therapies for hormone naïve and castration-resistant prostate cancers with or without previous chemotherapy

Hormonal manipulation plays a significant role in the treatment of advanced hormone naïve prostate cancer and castration-resistant prostate cancer (CRPC) with or without previous chemotherapy. Combination of gonadotropin releasing hormone (GnRH) agonists and androgen receptor (AR) antagonists (combined androgen blockade; CAB) is the first line therapy for advanced hormone naïve prostate cancer, but current strategies are developing novel GnRH antagonists to overcome disadvantages associated with GnRH agonist monotherapy and CAB in the clinical setting. Abiraterone acetate and enzalutamide are hormonal agents currently available for patients with CRPC and are both shown to improve overall survival versus placebo. Recently, in clinical trials, testosterone has been administered in cycles with existing surgical and chemical androgen deprivation therapies (ADT) (intermittent therapy) to CRPC patients of different stages (low risk, metastatic) to abate symptoms of testosterone deficiency and reduce cost of treatment from current hormonal therapies for patients with CRPC. This review will provide an overview on the therapeutic roles of hormonal manipulation in advanced hormone naïve and castration-resistant prostate cancers, as well as the development of novel hormonal therapies currently in preclinical and clinical trials.

Uptake carriers and oncology drug safety

Members of the solute carrier (SLC) family of transporters are responsible for the cellular influx of a broad range of endogenous compounds and xenobiotics in multiple tissues. Many of these transporters are highly expressed in the gastrointestinal tract, liver, and kidney and are considered to be of particular importance in governing drug absorption, elimination, and cellular sensitivity of specific organs to a wide variety of oncology drugs. Although the majority of studies on the interaction of oncology drugs with SLC have been restricted to the use of exploratory in vitro model systems, emerging evidence suggests that several SLCs, including OCT2 and OATP1B1, contribute to clinically important phenotypes associated with those agents. Recent literature has indicated that modulation of SLC activity may result in drug-drug interactions, and genetic polymorphisms in SLC genes have been described that can affect the handling of substrates. Alteration of SLC function by either of these mechanisms has been demonstrated to contribute to interindividual variability in the pharmacokinetics and toxicity associated with several oncology drugs. In this report, we provide an update on this rapidly emerging field.

Androgen-deprivation therapy alone or with docetaxel in non-castrate metastatic prostate cancer (GETUG-AFU 15): a randomised, open-label, phase 3 trial

BACKGROUND

Early chemotherapy might improve the overall outcomes of patients with metastatic non-castrate (ie, hormone-sensitive) prostate cancer. We investigated the effects of the addition of docetaxel to androgen-deprivation therapy (ADT) for patients with metastatic non-castrate prostate cancer.

METHODS

In this randomised, open-label, phase 3 study, we enrolled patients in 29 centres in France and one in Belgium. Eligible patients were older than 18 years and had histologically confirmed adenocarcinoma of the prostate and radiologically proven metastatic disease; a Karnofsky score of at least 70%; a life expectancy of at least 3 months; and adequate hepatic, haematological, and renal function. They were randomly assigned to receive to ADT (orchiectomy or luteinising hormone-releasing hormone agonists, alone or combined with non-steroidal antiandrogens) alone or in combination with docetaxel (75 mg/m(2) intravenously on the first day of each 21-day cycle; up to nine cycles). Patients were randomised in a 1:1 ratio, with dynamic minimisation to minimise imbalances in previous systemic treatment with ADT, chemotherapy for local disease or isolated rising concentration of serum prostate-specific antigen, and Glass risk groups. Patients, physicians, and data analysts were not masked to treatment allocation. The primary endpoint was overall survival. Efficacy analyses were done by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00104715.

FINDINGS

Between Oct 18, 2004, and Dec 31, 2008, 192 patients were randomly allocated to receive ADT plus docetaxel and 193 to receive ADT alone. Median follow-up was 50 months (IQR 39-63). Median overall survival was 58·9 months (95% CI 50·8-69·1) in the group given ADT plus docetaxel and 54·2 months (42·2-not reached) in that given ADT alone (hazard ratio 1·01, 95% CI 0·75-1·36). 72 serious adverse events were reported in the group given ADT plus docetaxel, of which the most frequent were neutropenia (40 [21%]), febrile neutropenia (six [3%]), abnormal liver function tests (three [2%]), and neutropenia with infection (two [1%]). Four treatment-related deaths occurred in the ADT plus docetaxel group (two of which were neutropenia-related), after which the data monitoring committee recommended treatment with granulocyte colony-stimulating factor. After this recommendation, no further treatment-related deaths occurred. No serious adverse events were reported in the ADT alone group.

INTERPRETATION

Docetaxel should not be used as part of first-line treatment for patients with non-castrate metastatic prostate cancer.

FUNDING

French Health Ministry and Institut National du Cancer (PHRC), Sanofi-Aventis, AstraZeneca, and Amgen.

Neutropenia as a potential pharmacodynamic marker for docetaxel-based chemotherapy in men with metastatic castration-resistant prostate cancer

BACKGROUND

Docetaxel clearance appears increased in men who are castrated. Neutropenia in cycle 1 may be a pharmacodynamic marker for docetaxel, which may enable tailored dosing in metastatic castration-resistant prostate cancer (mCRPC).

PATIENTS AND METHODS

The association of cycle 1 neutropenia with overall survival (OS) was examined post hoc in a randomized phase II trial of 221 men with mCRPC who received docetaxel-prednisone combined with placebo or AT-101 (bcl-2 inhibitor); weekly blood cell counts were performed during the first cycle. Patients from both arms were combined because no outcome and toxicity differences were observed. OS was calculated from randomization by the Kaplan-Meier method, and Cox proportional hazards regression models were used to estimate the association with OS.

RESULTS

The difference in OS between men with day 8 ≥grade 3 neutropenia and those with ≤grade 2 neutropenia was significant after adjusting for trial stratification factors, pain, and performance status (hazard ratio [HR] 0.64; 2P = .048). Results were similar for logarithmic neutrophil counts adjusted for the risk group based on anemia, visceral metastasis, progression by bone scan and pain (HR 1.18; 2P = .07) for stratification factors (HR 1.20; 2P = .052) or both (HR, 1.20; 2P = .046). Men with ≥grade 3 neutropenia and ≥30% prostate-specific antigen level decline by day 90 had improved OS compared with men exhibiting neither (HR 0.51; 2P = .014).

CONCLUSIONS

For patients with mCRPC who received docetaxel, ≥grade 3 neutropenia on day 8 was prognostic for improved OS, which suggests its utility as a pharmacodynamic marker, in this hypothesis-generating analysis. Exploration of dose escalation of docetaxel to attain ≥grade 3 neutropenia on day 8 may be warranted.

Toxicity in patients receiving adjuvant docetaxel + hormonal treatment after radical radiotherapy for intermediate or high-risk prostate cancer: a preplanned safety report of the SPCG-13 trial

BACKGROUND

Radical radiotherapy (RT) combined with androgen deprivation therapy is currently the standard treatment for elderly patients with localized intermediate- or high-risk prostate cancer (PC). To increase the recurrence-free and overall survival, we conducted an adjuvant, randomized trial using docetaxel (T) in PC patients (Scandinavian Prostate Cancer Group trial 13).

METHODS

The inclusion criteria are the following: men >18 and ≤75 years of age, WHO/ECOG performance status 0--1, histologically proven PC within 12 months before randomization and one of the following: T2, Gleason 7 (4+3), PSA >10; T2, Gleason 8--10, any PSA; or any T3 tumors. Neoadjuvant/adjuvant hormone therapy is mandatory for all patients. The patients were randomized to receive six cycles of T (75 mgm(-2) d 1. cycle 21 d) or no docetaxel after radical RT (with a minimum tumor dose of 74 Gy). This study identifier number is NTC 006653848 (http://www.clinicaltrials.org).

RESULTS

In this preplanned safety analysis of 100 patients, T treatment induced grade (G) 3 adverse events (AEs) in 15 patients (30%) and G4 AEs in 30 patients (60%), mainly due to bone marrow toxicity. Neutropenia G3--4 was observed in 72% of the patients, febrile neutropenia was found in 24% of patients, neutropenic infection in 10% of patients and G3 infection without neutropenia in 4% of patients. Nonhematological G3 AEs were rare: anorexia, diarrhea, mucositis, nausea, pain (1 patient each) and fatigue (5). Other severe serious AEs related to T were pulmonary embolism and renal failure. However, only three patients discontinued T before completing the planned six cycles. No deaths had occurred. No patients in the control arm experienced G3--4 toxicities at 12 weeks after the randomization.

CONCLUSIONS

Adjuvant docetaxel chemotherapy after radiotherapy has a higher frequency of neutropenia than previous studies on patients with metastatic disease. Otherwise, the treatment was quite well tolerated.

The change of PSA doubling time and its association with disease progression in patients with biochemically relapsed prostate cancer treated with intermittent androgen deprivation

BACKGROUND

We sought to determine the change of PSA doubling time (PSADT) and its association with disease progression during intermittent androgen deprivation (IAD) therapy for prostate cancer.

METHODS

Data were retrospectively analyzed in 96 patients with biochemically relapsed prostate cancer (BRPC) treated with IAD since 1995. IAD consisted of LHRH-agonists ± antiandrogen given usually at PSA threshold (ng/ml) of 10-20, for 6-9 months. Cycles were repeated until the development of castration resistance. Mixed effects model was used to study PSADT change over cycles. Multivariate cox regression model was used to identify outcome-associated variables.

RESULTS

Patients received a mean of 2.8 treatment cycles over a mean follow-up time of 71 months. Fifty-seven (59%) remain on treatment and 39 (41%) developed PSA refractoriness (n = 8) or positive scans (n = 31). First off treatment interval PSADT (median 2.3 months) was significantly shorter than the baseline (median 7.34) but remained stable in subsequent cycles. Off treatment interval PSADT adjusted for testosterone recovery (median 3.7) was significantly longer than that based on all PSA determinations (median 2). Factors associated with disease progression were pre-treatment PSADT (≥6 vs. <6), first off treatment interval PSADT (≥3 vs. <3), and PSA nadir during the first treatment interval (<0.1 vs. ≥0.1).

CONCLUSIONS

During IAD for BRPC, PSADT becomes shorter, and is associated with testosterone recovery. PSADT before treatment and during the first off treatment interval is associated with disease progression. If prospectively validated these data may guide treatment with IAD and clinical trial design.

Beefing up prostate cancer therapy with performance-enhancing (anti-) steroids

In the May 26th issue of the New England Journal of Medicine, de Bono et al. report that the inhibition of androgen synthesis by abiraterone acetate prolonged the survival of men with prostate cancer previously treated by androgen suppression.

Castration-dependent pharmacokinetics of docetaxel in patients with prostate cancer

PURPOSE

To assess whether the low incidence of severe neutropenia in castrated men with prostate cancer treated with docetaxel is the result of changes in systemic clearance.

PATIENTS AND METHODS

A total of 10 noncastrated and 20 castrated men with prostate cancer were studied to achieve 80% power (α = .05) to detect at least a 25% change in the clearance of docetaxel. The erythromycin breath test was evaluated to determine hepatic activity of cytochrome P450 3A4 (CYP3A4), the main docetaxel-metabolizing enzyme. Additional studies were performed in rats and transfected cells overexpressing human or rodent transporters.

RESULTS

Docetaxel clearance was increased by approximately 100% in castrated men and was associated with a two-fold reduction in area under the curve (P = .0001), although hepatic activity of CYP3A4 was unchanged (P = .26). In rats, castration was associated with higher uptake of docetaxel in the liver and a concurrent increase in the expression of rOat2 (Slc22a7), an organic anion transporter that regulates, in part, the transfer of docetaxel from the circulation into hepatocytes.

CONCLUSION

It is recommended that castration- and/or hormone-related changes in the clearance of oncology drugs should be considered as a possible risk factor for treatment failure.

Efficacy and safety of docetaxel plus prednisolone chemotherapy for metastatic hormone-refractory prostate adenocarcinoma: single institutional study in Korea

PURPOSE

To assess the efficacy and safety of treating Korean patients with metastatic hormone-refractory prostate cancer (HRPC) using docetaxel plus prednisolone chemotherapy.

MATERIALS AND METHODS

This was a retrospective cohort study performed in 98 patients with metastatic HRPC between October 2003 and April 2008. After screening, 72 patients fit the eligibility criteria for inclusion in this study. Treatment consisted of 5 mg prednisolone twice daily and 75 mg/m² docetaxel once every 3 weeks.

RESULTS

Patient demographic characteristics included: median age 67 years (range, 51~86), median ECOG performance status 1 (0~2), Gleason score ≥8 in 61 patients (86%), and median serum PSA 45.5 ng/mL (range, 3.7~2,420.0). A total of 405 cycles of treatment were administered with a median 6 cycles (range, 1~20) per patient. The median docetaxel dose-intensity was 24.4 mg/m(2)/week (range, 17.5~25.6). A PSA response was seen in 51% of 63 evaluable patients at 12 weeks and maximal PSA decline ≥50% in 59% of 70 evaluable patients. Tumor response was evaluated in 13 patients, 4 patients achieved PR, and 5 patients had SD with a response rate of 31%. With a median follow-up duration of 23.1 months (95%CI, 16.7~29.5), the median time to PSA progression was 5.1 months (95%CI, 4.5~5.8) and median overall survival was 22.8 months (95%CI, 16.6~29.1). Nine (13%) patients experienced grade 3 or higher febrile neutropenia.

CONCLUSION

This chemotherapy regimen (docetaxel every 3 weeks plus prednisolone daily) demonstrated a strong response in Korean patients with metastatic HRPC, while the toxicity profile was manageable and similar to that observed in Western patients.

Novel histone deacetylase inhibitors in clinical trials as anti-cancer agents

Histone deacetylases (HDACs) can regulate expression of tumor suppressor genes and activities of transcriptional factors involved in both cancer initiation and progression through alteration of either DNA or the structural components of chromatin. Recently, the role of gene repression through modulation such as acetylation in cancer patients has been clinically validated with several inhibitors of HDACs. One of the HDAC inhibitors, vorinostat, has been approved by FDA for treating cutaneous T-cell lymphoma (CTCL) for patients with progressive, persistent, or recurrent disease on or following two systemic therapies. Other inhibitors, for example, FK228, PXD101, PCI-24781, ITF2357, MGCD0103, MS-275, valproic acid and LBH589 have also demonstrated therapeutic potential as monotherapy or combination with other anti-tumor drugs in CTCL and other malignancies. At least 80 clinical trials are underway, testing more than eleven different HDAC inhibitory agents including both hematological and solid malignancies. This review focuses on recent development in clinical trials testing HDAC inhibitors as anti-tumor agents.

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.

Starving the addiction: new opportunities for durable suppression of AR signaling in prostate cancer

Clinical data and models of human disease indicate that androgen receptor (AR) activity is essential for prostate cancer development, growth, and progression. The dependence of prostatic adenocarcinoma on AR signaling at all stages of disease has thereby been exploited in the treatment of disseminated tumors, for which ablation of AR function is the goal of first-line therapy. Although these strategies are initially effective, recurrent tumors arise with restored AR activity, and no durable treatment has yet been identified to combat this stage of disease. New insights into AR regulation and the mechanisms underlying resurgent AR activity have provided fertile ground for the development of novel strategies to more effectively inhibit receptor activity and prolong the transition to therapeutic failure.