Phase II study of oxaliplatin versus oxaliplatin combined with infusional 5-fluorouracil in hormone refractory metastatic prostate cancer patients

Application of Approved Cisplatin Derivatives in Combination Therapy against Different Cancer Diseases

The problems with anticancer therapy are resistance and toxicity. From 3000 Cisplatin derivatives tested as antitumor agents, most of them have been rejected, due to toxicity. The aim of current study is the comparison of therapeutic combinations of the currently applied in clinical practice: Cisplatin, Carboplatin, Oxaliplatin, Nedaplatin, Lobaplatin, Heptaplatin, and Satraplatin. The literature data show that the strategies for the development of platinum anticancer agents and bypassing of resistance to Cisplatin derivatives and their toxicity are: combination therapy, Pt IV prodrugs, the targeted nanocarriers. The very important strategy for the improvement of the antitumor effect against different cancers is synergistic combination of Cisplatin derivatives with: (1) anticancer agents—Fluorouracil, Gemcitabine, Cytarabine, Fludarabine, Pemetrexed, Ifosfamide, Irinotecan, Topotecan, Etoposide, Amrubicin, Doxorubicin, Epirubicin, Vinorelbine, Docetaxel, Paclitaxel, Nab-Paclitaxel; (2) modulators of resistant mechanisms; (3) signaling protein inhibitors—Erlotinib; Bortezomib; Everolimus; (4) and immunotherapeutic drugs—Atezolizumab, Avelumab, Bevacizumab, Cemiplimab, Cetuximab, Durvalumab, Erlotinib, Imatinib, Necitumumab, Nimotuzumab, Nivolumab, Onartuzumab, Panitumumab, Pembrolizumab, Rilotumumab, Trastuzumab, Tremelimumab, and Sintilimab. An important approach for overcoming the drug resistance and reduction of toxicity of Cisplatin derivatives is the application of nanocarriers (polymers and liposomes), which provide improved targeted delivery, increased intracellular penetration, selective accumulation in tumor tissue, and enhanced therapeutic efficacy. The advantages of combination therapy are maximum removal of tumor cells in different phases; prevention of resistance; inhibition of the adaptation of tumor cells and their mutations; and reduction of toxicity.

Effectiveness of Platinum-Based Chemotherapy in Patients With Metastatic Prostate Cancer: Systematic Review and Meta-analysis

BACKGROUND

Taxanes are the only cytotoxic drugs that have demonstrated a survival benefit for patients with castration-resistant prostate cancer (CRPC), but there is some evidence that platinum compounds may also benefit such patients.

METHODS

We performed a systematic search on electronic databases. We sought prospective clinical studies testing platinum compounds for CRPC. Platinum compounds could be delivered alone or in combination with other drugs. Both randomized and nonrandomized studies were included for qualitative synthesis, only randomized studies were included for meta-analyses. Clinical overall response rate (cORR), prostate-specific antigen overall response rate (sORR), progression-free survival (PFS), overall survival (OS), and toxicity were the outcomes of interest.

RESULTS

We identified 53 studies delivering platinum agents for patients with CRPC. cORR varied from 0 to 82%, while sORR varied from 2% to 100%. Response rates were higher in patients who received combination treatments rather than platinum compounds alone. Pooled data from randomized trials demonstrated a statistically significant increase in both cORR (odds ratio = 5.3; 95% confidence interval, 1.89-14.92) and sORR (odds ratio = 2.07; 95% confidence interval, 1.33-3.22) when adding platinum compounds to chemotherapy. PFS varied from 2.1 to 12 months and OS 4.2 to 28 months with platinum-containing chemotherapy. Nausea and myelosuppression were the most common adverse effects. Toxicity was manageable in most studies.

CONCLUSION

Platinum compounds are a safe and active treatment for CRPC. Response rates are higher when cytotoxic chemotherapy containing platinum agents are compared to nonplatinum chemotherapy. Data on OS and PFS are inconclusive. More research is needed to evaluate whether platinum-based chemotherapy results in a survival benefit for patients with CRPC, as well as to establish predictive biomarkers.

Genome-Based Classification and Therapy of Prostate Cancer

In the past decade, multi-national and multi-center efforts were launched to sequence prostate cancer genomes, transcriptomes, and epigenomes with the aim of discovering the molecular underpinnings of tumorigenesis, cancer progression, and therapy resistance. Multiple biological markers and pathways have been discovered to be tumor drivers, and a molecular classification of prostate cancer is emerging. Here, we highlight crucial findings of these genome-sequencing projects in localized and advanced disease. We recapitulate the utility and limitations of current clinical practices to diagnosis, prognosis, and therapy, and we provide examples of insights generated by the molecular profiling of tumors. Novel treatment concepts based on these molecular alterations are currently being addressed in clinical trials and will lead to an enhanced implementation of precision medicine strategies.

Hormone Refractory Prostate Cancer (Hrpc): Present and Future Approaches of Therapy

The mainstay of therapy for patients with advanced prostate cancer still remains androgen deprivation, although response to this is invariably temporary. Most of the patients develop hormone-refractory disease resulting in progressive clinical deterioration and, ultimately, death. Until recently there has been no standard chemotherapeutic approach for hormone refractory prostate cancer (HRPC), the major benefits of chemotherapy being only palliative. The studies combining mitoxantrone plus a corticosteroid demonstrated that chemotherapy could be given to men with symptomatic HRPC with minimal toxicity and a significant palliation could be provided. Recently, results from 2 phase III randomized clinical trials demonstrating that a combination of docetaxel plus prednisone can improve survival in men with HRPC have propelled docetaxel-based therapy into the forefront of treatment options for these patients as the new standard of care. There is a promising activity of new drug combinations such as taxanes plus vinca alkaloids; bisphosphonates are assuming a prominent role in prostate therapy through their ability to prevent skeletal morbidity. Combinations of classic chemotherapeutic agents and biological drugs began to be tested in phase II-III trials and the first results appear interesting. This article focuses on combinations recently evaluated or under clinical development for the treatment of HRPC.

Treatment Options in Hormone-refractory Metastatic Prostate Carcinoma

Prostate cancer represents one of the most important health problems in industrialized countries. It is the second leading cause of cancer-related death in the United States. Therapeutic options are different according to the stage of the disease at the diagnosis. Patients with localized disease may be treated with surgery or radiation, whereas the treatment for patients with a metastatic disease is purely palliative. Hormonal treatment represents the standard therapy for stage IV prostate cancer, but patients ultimately become unresponsive to androgen ablation and are classified as hormone-refractory prostate cancer patients. The molecular mechanisms involved in progression in hormone resistance are characterized by mutations, down and up-regulation in the androgen receptor gene, mutations in p53 and over-expression of Bcl2 and other alterations in genes and in gene expression. The important thing is that we understand these mechanisms to define potential therapeutic agents for the treatment of hormone-refractory prostate cancer patients. Conventional options for patients with hormone-refractory prostate cancer include secondary hormone therapy, radiotherapy and cytotoxic chemotherapy. The commonest antineoplastic agents are mitoxantrone, estramustine and taxanes. Despite an improvement In the palliative benefit, none of these agents has demonstrated a beneficial impact on the overall survival of patients. Therefore, there is no standard therapy for these patients, thus we need new approaches which should be studied in clinical trials. The evaluation and incorporation of new agents into current treatment regimens could have a role in the treatment of hormone-refractory prostate cancer, but their efficacy has not yet been demonstrated.

Chemotherapy oxaliplatin sensitizes prostate cancer to immune checkpoint blockade therapies via stimulating tumor immunogenicity

Even though standard treatment options are available for prostate cancer patients, prostate cancer is still a leading cause of death in many Western countries due to drug resistance and recurrence. Immune checkpoint blockade therapy has been proved to be very effective in some melanoma patients, which might dependent on the preconditioned immune system. Here we explored the effect of chemotherapy (oxaliplatin) in combination with immune checkpoint blockade therapy (anti‑PD‑1 treatment) in prostate cancer cell lines and pre‑clinical animal models. We found that oxaliplatin is effective in castration‑resistant cells and enhanced the response of prostate cancer to anti‑PD‑1 antibody treatment. Oxaliplatin stimulated the immunogenic potential and established a pro‑immune microenvironment in prostate cancer. In conclusion, oxaliplatin sensitized anti‑PD‑1 treatment in prostate cancer and this combination may be an option for castration‑resistant prostate cancer patients.

Anti-tumour activity of platinum compounds in advanced prostate cancer-a systematic literature review

BACKGROUND

For men with advanced castration-resistant prostate cancer (CRPC), several treatment options are available, including androgen receptor (AR) pathway inhibitors (abiraterone acetate, enzalutamide), taxanes (docetaxel, cabazitaxel) and the radionuclide (radium-223). However, cross-resistance is a clinically relevant problem. Platinum compounds have been tested in a number of clinical trials in molecularly unselected prostate cancer patients. Advances in CRPC molecular profiling have shown that a significant proportion of patients harbour DNA repair defects, which may serve as predictive markers for sensitivity to platinum agents.

OBJECTIVE

To systematically identify and analyse clinical trials that have evaluated platinum agents in advanced prostate cancer patients.

METHODS

PubMed was searched to identify published clinical trials of platinum agents in advanced prostate cancer. The PRIMSA statement was followed for the systematic review process. Identified trials are analysed for study design, statistical plan, assessments of anti-tumour activity and the potential value of predictive biomarkers.

RESULTS

A total of 163 references were identified by the literature search and 72 publications that met the selection criteria were included in this review; of these 33 used carboplatin, 27 cisplatin, 6 satraplatin, 4 oxaliplatin and 2 other platinum compounds. Overall, anti-tumour activity varies in the range of 10%-40% for objective response and 20%-70% for PSA decline ≥50%. Response seemed highest for the combinations of carboplatin with taxanes or oxaliplatin with gemcitabine. The interpretation of the clinical data is limited by differences in response criteria used and patient populations studied.

CONCLUSION

Platinum compounds have moderate anti-tumour activity in molecularly unselected patients with advanced prostate cancer. Translational evidence of DNA repair deficiency should be leveraged in future studies to select prostate cancer patients most likely to benefit from platinum-based therapy.

Assessment of anticancer-treatment outcome in patients with metastatic castration-resistant prostate cancer-going beyond PSA and imaging, a systematic literature review

BACKGROUND

In the past years, there has been significant progress in anticancer drug development for patients with metastatic castration-resistant prostate cancer (CRPC). However, the current instruments to assess clinical treatment response have limitations and may not sufficiently reflect patient benefit. Our objective was to systematically identify tools to evaluate both patient benefit and clinical anticancer-treatment response as basis for an international consensus process and development of a specific pragmatic instrument for men with CRPC.

METHODS

PubMed, Embase and CINAHL were searched to identify currently available tools to assess anticancer-treatment benefit, other than standard imaging procedures and prostate-specific antigen measurements, namely quality of life (QoL), detailed pain assessment, physical function and objective measures of other complex cancer-related syndromes in patients with CRPC. Additionally, all CRPC phase III trials published in the last 5 years were reviewed as well as studies using physical function tools in a general cancer population. The PRIMSA statement was followed for the systematic review process.

RESULTS

The search generated 1096 hits, 185 full-text papers were screened and finally 73 publications were included. Additional 89 publications were included by hand-search. We identified a total of 98 tools used in CRPC trials and grouped these into three categories: 22 tools assessing QoL domains and subgroups, 47 tools for pain assessment and 29 tools for objective measures, mainly physical function and assessment of skeletal disease burden.

CONCLUSION

A wide variety of assessment tools and also efforts to standardize and harmonize patient-reported outcomes and pain assessment were identified. However, the specific needs of the increasing CRPC population living longer with their incurable cancer are insufficiently captured and objective physical outcome measures are under-represented. In the age of new anticancer drug targets and principles, new methods to monitor patient relevant outcomes of antineoplastic therapy are of utmost importance.

Gemcitabine-oxaliplatin plus prednisolone is active in patients with castration-resistant prostate cancer for whom docetaxel-based chemotherapy failed

Background:

There has been no previous study on the activity of gemcitabine in combination with oxaliplatin (GemOx) for castration-resistant prostate cancer (CRPC).

Methods:

The GemOx was preclinically tested for cytotoxic activity in human prostate cancer cell lines. Clinically, patients with CRPC who failed prior docetaxel were treated with gemcitabine 1000 mg m⁻² and oxaliplatin 100 mg m⁻² intravenously every 2 weeks and prednisolone 5 mg orally twice daily. The primary end point was the prostate-specific antigen (PSA) response rate.

Results:

The GemOx displayed synergistic effects based on Chou and Talalay analysis. In the phase II study, 33 patients were accrued. The median dose of docetaxel exposure was 518 mg m⁻². A total of 270 cycles were administered with a median of eight cycles per patient. A PSA response rate was 55% (95% CI, 38–72) and radiologic response rate was 82% (9 out of 11). With a median follow-up duration of 20.5 months, the median time to PSA progression was 5.8 months (95% CI, 4.4–7.2) and the median overall survival was 17.6 months (95% CI, 12.6–22.6). The most frequently observed grade 3 or 4 toxicities were neutropenia (13%) and thrombocytopenia (13%).

Conclusions:

The GemOx is active and tolerable in patients with metastatic CRPC after docetaxel failure (NCT 01487720).

Evolving treatment paradigms for locally advanced and metastatic prostate cancer

While men with early stage prostate cancer typically enjoy long-term survival after definitive management, for those who present with locally advanced or metastatic disease, survival is compromised. Multimodality therapy can prolong survival in these patients, with state-of-the-art options including intensity-modulated radiation or brachytherapy in conjunction with androgen ablation, adjuvant androgen ablation and/or chemotherapy with radical retropubic prostatectomy. In addition, novel biological therapies are being explored to target the unique molecular changes in prostate cancer cells and their interactions with the microenvironment. With these advances the outlook will undoubtedly improve, even for patients presenting with advanced disease. Careful application of these emerging therapies to a select group of prostate cancer patients most likely to obtain benefit from them is the challenge for urologists, medical oncologists and radiation oncologists for the future.

Gene expression signature predicting high-grade prostate cancer responses to oxaliplatin

Prostate cancer is one of the leading causes of cancer-related deaths among men. Several prognostic factors allow differentiation of low-grade tumors from high-grade tumors with high metastatic potential. High-grade tumors are currently treated with hormone therapy, to which taxanes are added when the tumors become resistant to castration. Clinical trials with other anticancer agents did not take into account the genetic backgrounds of the tumors, and most trials demonstrated low response rates. Here we used an in silico approach to screen for drug candidates that might be used as alternatives to taxanes, on the basis of a published expression signature involving 86 genes that could distinguish high-grade and low-grade tumors (Proc Natl Acad Sci USA 103:10991-10996, 2006). We explored the National Cancer Institute databases, which include data on the gene expression profiles of 60 human tumor cell lines and the in vitro sensitivities of the cell lines to anticancer drugs, and we identified several genes in the signature for which expression levels were correlated with chemosensitivity. As an example of the validation of this in silico approach, we identified a set of six genes for which expression levels could predict cell sensitivity to oxaliplatin but not cisplatin. This signature was validated in vitro through silencing of the genes in DU145, LNCaP, and C4-2B prostate cancer cells, which was accompanied by changes in oxaliplatin but not cisplatin cytotoxicity. These results demonstrate the relevance of our approach for the identification of both alternative treatments for high-grade prostate cancers and new biomarkers to predict clinical tumor responses.

Constitutive and treatment-induced CXCL8-signalling selectively modulates the efficacy of anti-metabolite therapeutics in metastatic prostate cancer

BACKGROUND

The current study was undertaken to characterize the effect of anti-metabolites on inducing CXCL8 signaling and determining whether the constitutive and/or drug-induced CXCL8 signaling in metastatic prostate cancer (CaP) cells modulates their sensitivity to this class of agent.

METHODS

The response of metastatic CaP cells to 5-Fluorouracil (5-FU), Pemetrexed or Tomudex was determined using cell count assays, flow cytometry and PARP cleavage analysis. Quantitative-PCR, ELISA and immunoblots were employed to determine effects of drugs or CXCL8 administration on target gene/protein expression.

RESULTS

Administration of 5-FU but not pemetrexed potentiated CXCL8 secretion and increased CXCR1 and CXCR2 gene expression in metastatic PC3 cells. Consistent with this, the inhibition of CXCL8 signaling using a CXCR2 antagonist, AZ10397767, increased the cytotoxicity of 5-FU by 4-fold (P<0.001), and increased 5-FU-induced apoptosis in PC3 cells (P<0.01). In contrast, while administration of AZ10397767 had no effect on the sensitivity of pemetrexed, the CXCR2 antagonist exerted the greatest effect in increasing the sensitivity of PC3 cells to Tomudex, a directed thymidylate synthase (TS) inhibitor. Subsequent experiments confirmed that administration of recombinant human CXCL8 increased TS expression, a response mediated in part by the CXCR2 receptor. Moreover, siRNA-mediated knockdown of the CXCL8-target gene Bcl-2 increased the sensitivity of PC3 cells to 5-FU.

CONCLUSIONS

CXCL8 signaling provides a selective resistance of metastatic prostate cancer cells to specific anti-metabolites by promoting a target-associated resistance, in addition to underpinning an evasion of treatment-induced apoptosis.

Pemetrexed as second-line chemotherapy for castration-resistant prostate cancer after docetaxel failure: results from a phase II study

OBJECTIVE

Although there is no standard treatment after docetaxel failure in patients with castration-resistant prostate cancer (CRPC), second-line chemotherapy is increasingly required. Its mechanism of action and toxicity profile make pemetrexed suitable for testing in this setting.

METHODS AND MATERIALS

Patients with docetaxel-resistant CRPC received pemetrexed 500 mg/m(2) every 3 weeks for 6 courses. The usual premedication with vitamin supplementation and dexamethasone prophylaxis was regularly administered. The primary objective was to quantify the biochemical response rate.

RESULTS

The biochemical response rate was 10.5% (95% CI 1.3-33.1), with 2 patients showing a reduction in prostate specific antigen (PSA) of ≥50%. The null hypothesis that the PSA response rate would be less than 20% was therefore accepted, and patient accrual was stopped after the evaluation of the 19th patient. The 1-year overall survival rate was 61.5%, with a median survival of 14 months. A considerable proportion of the patients (36%) were withdrawn from the study because of hematologic and nonhematologic toxicity.

CONCLUSIONS

Our experience with pemetrexed in CRPC patients appears discouraging in terms of activity and toxicity. No further studies of this drug should be performed in CRPC patients.

Phase II trial of oxaliplatin and capecitabine after progression to first-line chemotherapy in androgen-independent prostate cancer patients

INTRODUCTION

Docetaxel plus prednisone is the current standard of care in first-line chemotherapy for metastatic hormone-refractory prostate cancer. However, there is no agent proven as effective after progression to standard docetaxel-based therapy. Platins and capecitabine have shown activity in this setting.

PATIENTS AND METHODS

A total of 14 patients were included in this prospective, single-center trial. All patients had progressed to first-line docetaxel-based treatment. Patients received oxaliplatin 100 mg/sqm on D1 and capecitabine 1000 mg/sqm/bid on days 1 to 14 every 21 days.

RESULTS

Median number of cycles was 3. No unexpected toxicity was observed. Only grade 3 toxicity reported was grade 3 anemia. Of the 14 patients, 3 presented grade 2 neuropathy which was spontaneously resolved. Prostate-specific antigenresponse rate was 57%, with a median time to progression of 14.5 weeks, and overall survival of 24 weeks.

CONCLUSIONS

In the second-line setting, after receiving docetaxel-based chemotherapy, the combination of oxaliplatin and capecitabine offers promising activity with an excellent safety profile.

Quantitative analysis of the enzymes associated with 5-fluorouracil metabolism in prostate cancer biopsies

Orotate phosphoribosyl transferase (OPRT) is the initial enzyme of 5-FU activation, in which 5-FU is converted to 5-fluorouridinemonophosphate. Dihydropyrimidine dehydrogenase (DPD) is a degrading enzyme that catabolizes 5-FU. In this study, we investigated the expression of these enzymes in normal prostate gland (NP), hormone-sensitive prostate cancer (HSPC), and hormone-refractory prostate cancer (HRPC). The prostatic tissue specimens were obtained from patients who had undergone prostate needle biopsies without any treatments or with PSA failure after initial androgen deprivation. The tissue samples derived from formalin-fixed, paraffin-embedded (FFPE) sections were prepared by laser-capture microdissection, and from them RNA was extracted. The levels of OPRT and DPD mRNA expression were examined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). The level of OPRT mRNA expression in the HSPC or the HRPC specimens was significantly higher than that in the NP specimens. There was a significant correlation between OPRT mRNA expression levels and the tumor pathological grade. Furthermore, the OPRT/ DPD expression ratio, a powerful predictive factor to evaluate 5-FU sensitivity, in the HRPC group was significantly higher than that in the low-grade HSPC group. Thus, the quantitative evaluation for these enzymes based on phosphorylation of 5-FU may be an effective option for some prostate cancer patients, particularly HRPC group.

The synergistic effect of recombinant human endostatin (YH-16) combined with oxaliplatin on human colorectal carcinoma

This study was designed to investigate the effect of recombinant human endostatin (YH-16) combined with oxaliplatin (L-OHP) on the growth of orthotopically-implanted human colorectal carcinoma in nude mice. Tumour volumes and weights were measured after therapy. Tumour cell morphology was observed by light and electron microscopy. Apoptosis was detected using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling (TUNEL) assay, and vascular endothelial growth factor (VEGF) expression and microvessel density (MVD) were determined by immunohistochemical staining. Tumour volumes in all treatment groups were significantly reduced compared with controls. YH-16 and L-OHP either alone or in combination caused tumour cell apoptosis, except in the YH-16 low-dose group. MVD was strongly inhibited in the treatment groups compared with the controls, although only YH-16 combined with L-OHP or L-OHP alone decreased VEGF expression. No obvious change in side-effects occurred. In conclusion, YH-16 combined with L-OHP inhibited growth and induced apoptosis in orthotopically-transplanted human colorectal carcinoma in nude mice without increasing side-effects.

Oxaliplatin plus gemcitabine as a salvage schedule for hormone-refractory prostate adenocarcinoma

We report a case of hormone-refractory prostate cancer (HRPC) treated with oxaliplatin plus gemcitabine in a third-line schedule after liver progression, with an excellent clinical, biochemical and radiological response and with an acceptable tolerance. Prior chemotherapy regimens included docetaxel plus estramustine and oral etoposide. To our knowledge, this is the first report that shows this approach in an HRPC patient.

Chemotherapy-induced CXC-chemokine/CXC-chemokine receptor signaling in metastatic prostate cancer cells confers resistance to oxaliplatin through potentiation of nuclear factor-kappaB transcription and evasion of apoptosis

Constitutive activation of nuclear factor (NF)-kappaB is linked with the intrinsic resistance of androgen-independent prostate cancer (AIPC) to cytotoxic chemotherapy. Interleukin-8 (CXCL8) is a transcriptional target of NF-kappaB whose expression is elevated in AIPC. This study sought to determine the significance of CXCL8 signaling in regulating the response of AIPC cells to oxaliplatin, a drug whose activity is reportedly sensitive to NF-kappaB activity. Administration of oxaliplatin to PC3 and DU145 cells increased NF-kappaB activity, promoting antiapoptotic gene transcription. In addition, oxaliplatin increased the transcription and secretion of CXCL8 and the related CXC-chemokine CXCL1 and increased the transcription and expression of CXC-chemokine receptors, especially CXC-chemokine receptor (CXCR) 2, which transduces the biological effects of CXCL8 and CXCL1. Stimulation of AIPC cells with CXCL8 potentiated NF-kappaB activation in AIPC cells, increasing the transcription and expression of NF-kappaB-regulated antiapoptotic genes of the Bcl-2 and IAP families. Coadministration of a CXCR2-selective antagonist, AZ10397767 (Bioorg Med Chem Lett 18:798-803, 2008), attenuated oxaliplatin-induced NF-kappaB activation, increased oxaliplatin cytotoxicity, and potentiated oxaliplatin-induced apoptosis in AIPC cells. Pharmacological inhibition of NF-kappaBorRNA interference-mediated suppression of Bcl-2 and survivin was also shown to sensitize AIPC cells to oxaliplatin. Our results further support NF-kappaB activity as an important determinant of cancer cell sensitivity to oxaliplatin and identify the induction of autocrine CXCR2 signaling as a novel mode of resistance to this drug.

Weekly paclitaxel and high-dose 5-fluorouracil plus leucovorin in hormone-refractory prostate cancer: In vitro combined effects and a Phase II trial

PURPOSE

Paclitaxel and 5-fluorouracil have been used to treat hormone-refractory prostate cancer with some success. In vitro data suggest that the combined cytotoxicity may be sequence dependent. Thus, we explored the combined effects of the 2 agents, both in vitro and in vivo.

PATIENTS AND METHODS

The combined cytotoxicity of paclitaxel and 5-fluorouracil, and the possible schedule dependence were studied in vitro using PC-3 and DU145 cells and the microculture tetrazolium assay. There were 23 patients with hormone-refractory prostate cancer treated with the regimen T-HDFL: paclitaxel 90 mg/m2 intravenously 1 hour on days 1 and 8; 5-fluorouracil 2000 mg/m2; and leucovorin 300 mg/m2 intravenous 24-hour infusion on days 2 and 9, which repeated every 21 days. The allowed percentage of bone marrow irradiation was 50%.

RESULTS

Significant synergistic cytotoxicity was seen only when paclitaxel was given 24 hours before 5-fluorouracil. With the T-HDFL regimen, 11 (52%) of the 21 evaluable patients had > or = 50% reduction of prostate-specific antigen, lasting for 6 weeks. Of the 7 patients with measurable disease, 2 had a partial response. Median overall survival was 14.1 months. Grade III/IV leukopenia occurred in 2 patients. There was no treatment-related death. Toxicities were well tolerated.

CONCLUSIONS

The combined cytotoxicity of paclitaxel and 5-fluorouracil is schedule dependent. It is feasible to administer weekly paclitaxel and high-dose 5-fluorouracil infusions in patients with hormone-refractory prostate cancer. Our findings may serve as an important rationale for future trial design.

Phase I and pharmacokinetic trial of AP5346, a DACH–platinum–polymer conjugate, administered weekly for three out of every 4 weeks to advanced solid tumor patients

PURPOSE

To determine the maximum tolerated dose (MTD) safety and pharmacokinetics of AP5346, a copolymer-linked 1,2-diaminocyclohexane(DACH)-platinum compound, in advanced solid tumor patients.

EXPERIMENTAL DESIGN

AP5346 was administered as a 1-hour IV infusion on days 1, 8, 15 of a 28-day cycle. Seven dose levels (DL) were explored: DL1: 40 mg platinum (Pt)/m2 (1 patient); DL2: 80 (1); DL3: 160 (3); DL4: 320 (3); DL5: 640 (6); DL6: 850 (6); DL7: 1280 (6) mg Pt/m2. Dose-limiting toxicity (DLT) included infusion omission and cycle delay >2 weeks.

RESULTS

Twenty-six patients received 41 cycles (median 1/patient, range 1-4). No DLT occurred in DL 1-4; 1 DLT in DL5 (RD; renal insufficiency), two in DL6 (MTD; vomiting; fatigue) and 5 in DL7 (neutropenic infection with diarrhea; neutropenia with vomiting; vomiting with fatigue; renal insufficiency; and fatigue). Two deaths occurred due to renal insufficiency (DL5); in both cases patients had disease in or surrounding genitourinary tract whose contribution could not be accurately discerned. Grade 1-2 creatinine abnormalities occurred in seven patients. Nausea/emesis was frequent (92%), reaching grade 3-4 (23%), but controlled by antiemetics. Grade 2-4 allergic reactions occurred in 4 patients. Cmax and AUC increased linearly with dose for total plasma platinum and ultrafiltrate platinum. Antitumor activity included two partial responses in metastatic melanoma and ovarian cancer, and an additional CA-125 normalization (from 133 IU/l) in a suspected ovarian cancer.

CONCLUSIONS

AP5346 administered weekly for 3 weeks out of every four is tolerated up to a dose of 640 mg Pt/m2 on the first cycle when given with antiemetic prophylaxis. The pharmacokinetics of AP5346 indicates a prolonged half-life, and evidence of antitumor activity was observed at this dose level.

Chemotherapy for hormone-refractory prostate cancer

BACKGROUND

Prostate cancer mainly affects elderly men, and its incidence has steadily increased over the last decade. The management of this disease is replete with controversy. In men with advanced, metastatic prostate cancer, hormone therapy is almost universally accepted as the initial treatment of choice and produces good responses in most patients. However, many patients will relapse and become resistant to further hormone manipulation; the outlook for these patients is poor. Many have disease extending to the skeleton, which is associated with severe pain. Therapies for these men include chemotherapy, bisphosphonates, palliative radiotherapy, and radioisotopes. Systemic chemotherapy has been evaluated in men with hormone-refractory prostate cancer (HRPC) for many years, with disappointing results. However, more recent studies with newer agents have shown encouraging results. There is therefore a need to explore the value of chemotherapy in this disease.

OBJECTIVES

The present review aims to assess the role of chemotherapy in men with metastatic HRPC. The major outcome was overall survival. Secondary objectives include the effect of chemotherapy on pain relief, prostate-specific antigen (PSA) response, quality of life, and treatment-related toxicity.

SEARCH STRATEGY

Trials were identified by searching electronic databases, such as MEDLINE, and handsearching of relevant journals and conference proceedings. There was no restriction of language or location.

SELECTION CRITERIA

Only published randomised trials of chemotherapy in HRPC patients were eligible for inclusion in this review. Randomised comparisons of different chemotherapeutic regimens, chemotherapy versus best standard of care or placebo, were relevant to this review. Randomised, dose-escalation studies were not included in this review.

DATA COLLECTION AND ANALYSIS

Data extraction tables were designed specifically for this review to aid data collection. Data from relevant studies were extracted and included information on trial design, participants, and outcomes. Trial quality was also assessed using a scoring system for randomisation, blinding, and description of patient withdrawal.

MAIN RESULTS

Out of 107 randomised trials of chemotherapy in advanced prostate cancer identified by the search strategy, 47 were included in this review and represented 6929 patients with HRPC. Only two trials compared the same chemotherapeutic interventions and therefore a meta-analysis was considered inappropriate. The quality of some trials was poor because of poor reporting, low-patient recruitment, or poor trial design. For clarity, trials were categorised according to the major drug used, but this was not a definitive grouping, since many trials used several agents and would be eligible for inclusion in a number of categories. Drug categories included estramustine, 5-fluorouracil, cyclophosphamide, doxorubicin, mitoxantrone, and docetaxel. Only studies using docetaxel reported a significant improvement in overall survival compared to best standard of care, although the increase was small (< 2.5 months). The mean percentage of patients achieving at least a 50% reduction in PSA compared to baseline was as follows: estramustine 48%; 5-fluorouracil 20%; doxorubicin 50% (one study only); mitoxantrone 33%; and docetaxel 52%. Pain relief was reported in 35% to 76% of patients receiving either single agents or combination regimens. A three weekly regime of docetaxel significantly improved pain relief compared to mitoxantrone plus prednisone (the latter regimen approved as standard therapy for HRPC in the USA). All chemotherapeutics, either as single agents or in combination, were associated with toxicity; the major ones being myelosuppression, gastrointestinal toxicity, cardiac toxicity, neuropathy, and alopecia. Quality of life was significantly improved with docetaxel compared to mitoxantrone plus prednisone.

AUTHORS' CONCLUSIONS

Patients with HRPC have not traditionally been offered chemotherapy as a routine treatment because of treatment-related toxicity and poor responses. Recent data from randomised studies, in particular those using docetaxel, have provided encouraging improvements in overall survival, palliation of symptoms, and improvements in quality of life. Chemotherapy should be considered as a treatment option for patients with HRPC. However, patients should make an informed decision based on the risks and benefits of chemotherapy.

Non-hormonal systemic therapy in men with hormone-refractory prostate cancer and metastases: a systematic review from the Cancer Care Ontario Program in Evidence-based Care's Genitourinary Cancer Disease Site Group

BACKGROUND

Prostate cancer that has recurred after local therapy or disseminated distantly is usually treated with androgen deprivation therapy; however, most men will eventually experience disease progression within 12 to 20 months. New data emerging from randomized controlled trials (RCTs) of chemotherapy provided the impetus for a systematic review addressing the following question: which non-hormonal systemic therapies are most beneficial for the treatment of men with hormone-refractory prostate cancer (HRPC) and clinical evidence of metastases?

METHODS

A systematic review was performed to identify RCTs or meta-analyses examining first-line non-hormonal systemic (cytotoxic and non-cytotoxic) therapy in patients with HRPC and metastases that reported at least one of the following endpoints: overall survival, disease control, palliative response, quality of life, and toxicity. Excluded were RCTs of second-line hormonal therapies, bisphosphonates or radiopharmaceuticals, or randomized fewer than 50 patients per trial arm. MEDLINE, EMBASE, the Cochrane Library, and the conference proceedings of the American Society of Clinical Oncology were searched for relevant trials. Citations were screened for eligibility by four reviewers and discrepancies were handled by consensus.

RESULTS

Of the 80 RCTs identified, 27 met the eligibility criteria. Two recent, large trials reported improved overall survival with docetaxel-based chemotherapy compared to mitoxantrone-prednisone. Improved progression-free survival and rates of palliative and objective response were also observed. Compared with mitoxantrone, docetaxel treatment was associated with more frequent mild toxicities, similar rates of serious toxicities, and better quality of life. More frequent serious toxicities were observed when docetaxel was combined with estramustine. Three trials reported improved time-to-disease progression, palliative response, and/or quality of life with mitoxatrone plus corticosteroid compared with corticosteroid alone. Single trials reported improved disease control with estramustine-vinblastine, vinorelbine-hydrocortisone, and suramin-hydrocortisone compared to controls. Trials of non-cytotoxic agents have reported equivocal results.

CONCLUSION

Docetaxel-based chemotherapy modestly improves survival and provides palliation for men with HRPC and metastases. Other than androgen deprivation therapy, this is the only other therapy to have demonstrated improved overall survival in prostate cancer in RCTs. Further investigations to identify more effective therapies for HRPC including the use of systemic therapies earlier in the natural history of prostate cancer are warranted.

A retrospective evaluation of second-line chemotherapy response in hormone-refractory prostate carcinoma

BACKGROUND

Epothilones and taxanes interfere with microtubule function. Ixabepilone, which is an epothilone-B analog, has activity against taxane-resistant cell lines and as first-line therapy for men with hormone-refractory prostate carcinoma (HRPC). Clinical cross-resistance of ixabepilone and taxanes in HRPC is unknown.

METHODS

Records were evaluated retrospectively from patients with HRPC who were treated on a randomized Phase II trial of ixabepilone with or without estramustine and who subsequently received taxane chemotherapy. Posttherapy declines in prostate-specific antigen (PSA) levels and time to PSA progression were defined by consensus criteria. The median survival was evaluated by using the Kaplan-Meier method.

RESULTS

Forty-nine patients who received ixabepilone with estramustine (28 patients) or without estramustine (21 patients) subsequently received second-line taxane therapy. Second-line PSA declines > or = 50% were achieved by 51% of patients (95% confidence interval [95% CI], 33-66%). Second-line PSA declines > or = 50% were achieved by 61% of patients (95% CI, 42-78%) who achieved a first-line PSA decline > or = 50% with ixabepilone, compared with 33% of patients (95% CI, 13-59%) who did not (P = 0.08). Patients who discontinued first-line ixabepilone treatment for disease progression were less likely to achieve a PSA decline > or = 50% in response to second-line, taxane-based therapy compared with patients who discontinued for toxicity or patient preference (36% vs. 71%; P = 0.01).

CONCLUSIONS

Second-line taxane chemotherapy after ixabepilone resulted in a substantial frequency of PSA declines. Although patients with ixabepilone-refractory disease were less likely to respond to second-line taxane chemotherapy, 36% did achieve a PSA response. These findings were consistent with incomplete clinical cross-resistance between the taxanes and the epothilones.

Expression of thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase, and orotate phosphoribosyl transferase in prostate cancer

The enzymes thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP), and orotate phosphoribosyl transferase (OPRT) are involved in the metabolism of the anticancer drug 5-fluorouracil. No reports have examined the expression of these enzymes in prostate cancer (CaP). A total of 25 previously untreated, hormone-sensitive CaP tissue samples and 11 benign prostatic hyperplasia (BPH) specimens were examined. Tissue of CaP and BPH tissue samples were obtained from formalin-fixed, paraffin-embedded sections by laser-captured microdissection, and then RNA was extracted. mRNA expression of TS, DPD, TP, and OPRT was analyzed by quantitative reverse transcriptase-polymerase chain reaction. TS and OPRT expression levels were significantly higher in CaP samples than in BPH. DPD expression level in poorly differentiated CaP was significantly lower than that in CaP with more favorable--well or moderately differentiated--histopathology.

Update on hormone-refractory prostate cancer

PURPOSE OF REVIEW

Androgen deprivation therapy is the cornerstone treatment for men with de novo or recurrent metastatic prostate cancer. Unfortunately, androgen deprivation therapy is primarily palliative, with nearly all men progressing to an androgen-independent state. Hormone-refractory prostate cancer presents significant management challenges and is the focus of this review.

RECENT FINDINGS

Investigations into the pathophysiology of hormone-refractory prostate cancer, the exploration of chemotherapeutic combinations, novel biological targets, skeletal protectants, and radiopharmaceuticals, as well as new prognostic tools are expanding the clinician's armamentarium and improving patient outcomes.

SUMMARY

Bisphosphonates and chemotherapy are providing effective palliative approaches. Phase II trials of taxane-based regimens show higher response rates and longer survival than has typically been achieved with existing standards. Two completed randomized phase III studies to be reported in mid-2004 will more definitively answer the question of whether currently available chemotherapy can improve survival.