The role of bisphosphonates in hormone-refractory prostate cancer

Men with advanced prostate cancer are at high risk for developing bone metastases, which result in clinically significant skeletal morbidity. Treatments that prevent skeletal complications in these patients could considerably improve their quality of life. Therefore, this paper reviews the role of bisphosphonates in the treatment of hormone-refractory prostate cancer (HRPC). Published studies were identified through MEDLINE searches, review of bibliographies of relevant articles, and review of abstracts from scientific meetings. Metastatic bone disease in men with HRPC results in skeletal complications such as pathologic fractures, spinal cord compression, and debilitating bone pain. First- and second-generation bisphosphonates, clodronate and pamidronate, had transient palliative effects that were not durable and did not prevent skeletal events in these patients. A small open-label study of ibandronate demonstrated significant reductions in pain, but these results have not been confirmed in a larger, randomized, controlled trial. To date, zoledronic acid is the only bisphosphonate that has demonstrated a statistically significant reduction in skeletal morbidity in this patient population. In a large, multicenter, randomized, placebo-controlled trial, treatment of men with HRPC and bone metastases with zoledronic acid significantly reduced skeletal-related events and provided a durable reduction of bone pain over 24 months compared with placebo. Zoledronic acid is the only bisphosphonate that has demonstrated efficacy for preventing skeletal complications in patients with HRPC and bone metastases. Therefore, initiation of zoledronic acid therapy should be considered to prevent skeletal morbidity and improve the quality of life of these patients.     

Use of bisphosphonates can dramatically improve pain in advanced hormone-refractory prostate cancer patients

INTRODUCTION: Approximately 85% of patients who die from prostate cancer present the spread of bone metastases. Even though the radiological appearance of such metastases is osteoblastic, it is now known that these lesions coexist in their microenvironment with blastic and lytic lesions. The process always begins with bone lysis by osteoclast proliferation, paralleling nearby bone deposition. The treatment options are palliative and have poor clinical response with short-lived improvement. We have studied the clinical effect of bisphosphonates (clodronate) in the treatment of skeletal complications from prostate cancer. MATERIALS AND METHODS: In an open prospective study, 58 patients with hormone-refractory prostate cancer with bone metastases were assessed from November 2000 to September 2003. The mean age was 70.3 y (range: 51-87 y). Bone scintigraphy, plain X-ray, assaying of prostate-specific antigen (PSA) and biochemical tests were requested before and following treatment. Patients were previously and subsequently assessed using the visual pain scale (0-10) and Karnofsky's index after the first and second intravenous (i.v.) infusions (administration of i.v. clodronate every 28 days) and every 4-6 months thereafter. Student's t-test was used for statistical analysis. RESULTS: A total of 53 patients (91.4%) showed improvement after the first and/or second cycle, which persisted for at least 4 months (average 6.3 months). The averages on the visual pain scale improved from 7.4 (range: 2-8) to 2.4 (0-7) and on Karnofsky's index from 43 (32-58) to 73 (50-82). The radiological appearance of the metastases improved in 27 patients (46.5%) and there were few relapses (six patients; 10.3%). CONCLUSIONS: Clodronate was effective in the treatment of skeletal complications from prostate cancer. There was an objective response in 91.4% of treated patients, with a marked improvement in the subjective visual pain scale evaluation as well as on Karnofsky's index, with low side effects.     

The use of bisphosphonates in the management of bone metastatic prostate cancer

Improved understanding of the pathophysiology of prostate cancer-induced metabolic bone disease implies that bisphosphonates may have a role in the treatment of this disorder. Although prostate cancer cells stimulate osteoblasts, resulting in a marked increase in bone volume and the classic radiologic aspect of sclerotic metastases, accelerated bone resorption has been reported by histomorphometric and biochemical studies. The significant relationship between the biochemical parameters of bone resorption and formation suggests a coupling between these two processes in metastatic prostate cancer. Several studies have demonstrated that administration of bisphosphonates is one of the most cost-effective palliative treatments for patients with prostate carcinoma and bone metastases, both as first-line and long-term therapy. With appropriate doses, a large proportion of patients can be maintained free of bone pain until death. Studies of the efficacy of lower doses to prevent skeletal morbidity in patients without metastases or with asymptomatic bone lesions are warranted.     

The androgen receptor in hormone-refractory prostate cancer

Advanced prostate cancer is responsive to hormone therapy that interferes with androgen receptor （AR） signalling. However, the effect is short-lived, as nearly all tumours progress to a hormone-refractory （HR） state, a lethal stage of the disease. Intuitively, the AR should not be involved because hormone therapy that blocks or reduces AR activity is not effective in treating HR tumours. However, there is still a consensus that AR plays an essential role in HR prostate cancer （HRPC） because AR signalling is still functional in HR tumours. AR signalling can be activated in HR tumours through several mechanisms. First, activation of intracellular signal transduction pathways can sensitize the AR to castrate levels of androgens. Also, mutations in the AR can change AR ligand specificity, thereby allowing it to be activated by non-steroids or anti-androgens. Finally, overexpression of the wild-type AR sensitizes itself to low concentrations of androgens. Therefore, drugs targeting AR signalling could still be effective in treating HRPC.     

Therapy of hormone-refractory prostate cancer

PSA-progression following primary ADT defines an androgen-refractory but still hormone sensitive PCA which might respond to secondary hormonal manipulations. Secondary hormonal manipulations will result in a PSA decline >50% in about 60-80% of the patients with a mean duration of 7-17 months depending on the type of treatment. PSA-progression following secondary endocrine treatment defines hormone-refractory prostate cancer (HRPCA) which might be treated by systemic chemotherapy. Based on the results of 2 prospective, randomized clinical phase-III trials comparing docetaxel and mitoxantrone, docetaxel results in a statistically significant survival benefit of 2.5 months, a significantly higher PSA- and pain response and represents the treatment of choice in the management of HRPCA. Bisphosphonates such as zoledronate represent another cornerstone in the management of PSA-progressive PCA demonstrating a significant benefit with regard to the prevention of skeletal related events. Furthermore, bisphosphonates might be indicated in the treatment of symptomatic bone pain. The current article critically reflects the various therapeutic options in the management of PSA progression following primary androgen deprivation for advanced prostate cancer.     

Fluorescence-guided surgery of prostate cancer bone metastasis

Background

The aim of this study is to investigate the effectiveness of fluorescence-guided surgery (FGS) of prostate cancer experimental skeletal metastasis.

Materials and methods

Green fluorescent protein-expressing PC-3 human prostate cancer cells (PC-3-green fluorescent protein) were injected into the intramedullary cavity of the tibia in 32 nude mice. After 2 wk, 16 of the mice underwent FGS; the other 16 mice underwent bright-light surgery (BLS). Half of BLS and FGS mice (8 mice in each group) received zoledronic acid (ZOL). Weekly fluorescence imaging of the mice was performed. Six weeks after surgery, metastases to lung and inguinal lymph node were evaluated by fluorescence imaging.

Results

The percentage of residual tumor after BLS and FGS was 9.9 ± 2.2% and 0.9 ± 0.3%, respectively (P < 0.001). FGS reduced recurrent cancer growth compared with BLS (P < 0.005). Although FGS alone had no significant effect on inguinal lymph node metastases, lung metastasis or disease-free survival (DFS), ZOL in combination with FGS significantly increased DFS (P = 0.01) in comparison with the combination of BLS and ZOL. ZOL reduced lymph node metastases (P = 0.033) but not lung metastasis.

Conclusions

FGS significantly reduced recurrence of experimental prostate cancer bone metastasis compared with BLS. The combination of FGS and ZOL increased DFS over BLS and ZOL. ZOL inhibited lymph node metastasis but not lung metastasis.     

Chemotherapy in hormone-refractory prostate cancer

The results of the TAX 327 and SWOG 99-16 trials for the first time showed an improvement in overall survival (OS) with docetaxel-based chemotherapy in patients with metastatic hormone-refractory prostate cancer. As such, 3-weekly (q3w) docetaxel plus low-dose prednisone is widely considered to be the treatment of choice for these patients. An updated survival analysis from TAX 327 confirms that benefits observed with docetaxel are sustained at 3 years. Furthermore, q3w docetaxel plus prednisone was effective in all patient subgroups investigated, regardless of age, presence or absence of pain, and performance status. Multivariate analysis has shown that prostate-specific antigen (PSA) concentrations and kinetics (pre-treatment PSA doubling time; PSADT) are independent prognostic factors for survival in the TAX 327 cohort, along with pain, number of metastatic sites and measurable disease. Patients with baseline PSA concentrations of <114 ng/mL and PSADT > or =55 days have a median overall survival of 25 months while those with PSA concentrations of > or =114 ng/mL and a PSADT of <55 days have a median overall survival of only 14 months. A PSA decline of > or 1=30% within 3 months' therapy with docetaxel is also a surrogate of OS. Measurements such as these, and the use of predictive nomograms, can assist the physician in identifying patients at high risk of disease progression who may benefit from earlier treatment with chemotherapy.     

Mechanisms governing bone metastasis in prostate cancer

Why does prostate cancer metastasize to bone? Why is there increased turnover of the bone matrix in the presence of prostate cancer? A recent autopsy study supports a traditional hypothesis that gross, anatomic patterns of blood flow influence the distribution of metastatic deposits. On the other hand, recent developments in animal models of prostate cancer bone metastasis have renewed interest in the traditional 'seed and soil' hypothesis: several studies point to specific biological interactions between prostate cancer cells and the bone microenvironment that can explain the tendency of prostate cancer cells to colonize bone and grow into clinically relevant metastatic deposits. Some studies implicate mechanisms including chemoattraction and enhanced adherence to bone endothelium. Additional data suggest that prostate cancer cells are 'osteomimetic', that is, they take on the properties and behaviors of osteoblasts or osteoclasts upon arrival in bone. These activities lead to enhanced turnover of the bone matrix and may explain the propensity of prostate cancer to grow in bone. Finally, a series of studies have implicated other molecular markers as distinguishing characteristics of bone-metastatic prostate cancer tissue.     

The potential role of bisphosphonates in prostate cancer

Skeletal morbidity secondary to metastases and osteoporosis is common in patients with advanced prostate cancer. Despite the typically sclerotic nature of prostate cancer metastases, osteoclast mediated osteolysis may play a significant role. This review addresses the newly recognised antitumour effects of bisphosphonates in addition to their role in inhibiting osteoclast mediated bone resorption. Both preclinical and clinical evidence of a role for bisphosphonates in the treatment and prevention of bone metastases secondary to prostate cancer is assessed.     

二膦酸盐治疗前列腺癌相关骨痛的疗效观察

目的　探讨二膦酸盐类药物对晚期前列腺癌骨转移疼痛的治疗价值。　方法　回顾性分析 4 0例因骨转移导致骨痛的晚期前列腺癌患者资料 ,无肝肾功能不全和病理性骨折 ,按去势后病情和治疗分为 3组 :A组 1 2例 ,切除睾丸后口服抗雄激素药物加服氯甲膦酸二钠 (固令 ) ;B组 1 7例 ,切除睾丸后口服抗雄激素药物 ;C组 1 1例 ,诊断为雄激素非依赖性前列腺癌 ,口服固令。采用视觉模拟疼痛评分 (VAS)和Karnofsky生活质量评分对 3组患者治疗前与治疗后 2、4周的疼痛程度与生活质量进行比较分析。　结果　 4周后 ,3组患者的骨痛明显改善 ,治疗前后VAS评分 :A组 7.3/ 2 .5 ,B组7.6 / 2 .3,C组 7.9/ 4 .6 ,P <0 .0 5 ;生活质量明显提高 ,治疗前后Karnofsky评分分别为 :A组 4 5 / 70 ,B组 4 0 / 70 ,C组 4 0 / 6 0 ,P <0 .0 5。 4例 (1 0 % )患者发生轻度恶心、呕吐和腹泻。　结论　二膦酸盐类药物是缓解晚期前列腺癌骨痛的有效手段     

Treatment options for hormone-refractory prostate cancer

Surgical or medical androgen deprivation therapy in its multiple variants represents the standard therapeutic approach in the management of metastatic prostate cancer resulting in a primary response rate of about 90%. However, about 90% of the men treated will develop PSA progression within 3-4 years resulting in androgen-independent and later on hormone-refractory prostate cancer. Management of AIPCA and HRPCA still represents a therapeutic challenge despite the development of new and effective treatment options. PSA progression following primary ADT defines an androgen-refractory but still hormone-sensitive PCA which might respond to secondary hormonal manipulations such as antiandrogen withdrawal, addition of nonsteroidal antiandrogens, and administration of estrogens, ketoconazole and hydrocortisone, and somatostatin analogues. Secondary hormonal manipulations will result in a PSA decline >50% in about 60-80% of the patients with a mean duration of 7-17 months depending on the type of treatment. PSA progression following secondary endocrine treatment defines hormone-refractory prostate cancer (HRPCA) which might be treated by systemic chemotherapy. Based on the results of two prospective, randomized clinical phase III trials comparing docetaxel and mitoxantrone, docetaxel results in a statistically significant survival benefit of 2.5 months, a significantly higher PSA and pain response, and represents the treatment of choice in the management of HRPCA.Bisphosphonates such as zoledronate represent another cornerstone in the management of PSA-progressive PCA demonstrating a significant benefit with regard to the prevention of skeletal-related events. Furthermore, bisphosphonates might be indicated in the treatment of symptomatic bone pain as has been demonstrated for ibandronate and zoledronate. The current article critically reflects on the various therapeutic options in the management of PSA progression following primary androgen deprivation for advanced prostate cancer. The development, rationale, and results of systemic chemotherapy are discussed critically and a therapeutic algorithm is demonstrated.     

Therapeutic options for hormone-refractory prostate cancer

For a long time, hormone-refractory prostate cancer was regarded as a chemoresistant tumor. The introduction of taxanes has prompted a change in this opinion. For the first time treatment with 75 mg/m(2) docetaxel every 3 weeks has evidenced a survival benefit in a phase III trial (median survival of 18.9 months versus 16.5 months with mitoxantrone). Further advantages were improved pain reduction and quality of life. Neutropenia was foremost among the side effects. Docetaxel is currently the standard treatment for hormone-refractory prostate cancer.The morbidity of metastatic hormone-refractory prostate cancer is influenced by bone metastases. Pain is a prominent feature. Skeletal complications are frequent. Therapy with 4 mg zoledronic acid reduced skeletal complications significantly in comparison to placebo. The most pronounced effect is the reduction of pathological fractures. Side effects include flu-like symptoms, muscle pain, and edemas. Zoledronic acid also belongs to the standard treatment of hormone-refractory prostate cancer with bone metastases.     

Molecular-targeted therapy for hormone-refractory prostate cancer

Molecular-targeted therapy is to treat pathologic pathways specifically in tumor cell or tumor microenvironment. Specific molecular-targeted therapeutic agents for hormone-refractory prostate cancer (HRPC) include endothelin-A receptor antagonist, EGF receptor (EGFR) inhibitor, platelet derived growth factor receptor (PDGFR) inhibitor, nuclear factor of kappaB (NF-kappaB) inhibitor, cyclooxygenase-2 (COX2) inhibitor, and active form of Vitamin D. These agents have been investigated in clinical trials. So far, none of the above-mentioned agent has shown a sufficient clinical efficacy alone. However, docetaxel-based combinations with thalidomide or calcitriol have promising clinical activities. Further investigations are needed to optimize the molecular-targeted agents in the combinations with chemotherapeutic agents for the treatment of HRPC.     

激素抵抗型前列腺癌分子靶向治疗的进展

前列腺癌是中老年男性最常见的恶性肿瘤之一,初期内分泌治疗有效,但几乎都会转变为激素抵抗型前列腺癌(hormone-refractory prostate cancer,HRPC)。多西紫杉醇联合强的松是HRPC标准的一线治疗,但目前尚无公认的二线治疗方案,本文拟着眼于HRPC形成的分子机制,介绍以肿瘤新生血管、细胞信号传导通路、凋亡、增殖及免疫调节为靶点治疗方法的最新进展。     

Hormonal chemotherapy for hormone-refractory prostate cancer

To our knowledge, no standard chemotherapy for patients with hormone-refractory prostate cancer (HRPC) has been established. Since most patients with HRPC are elderly and have bone metastasis, cytotoxic chemotherapy causes them to be at high risk for myelosuppression. Therefore, chemotherapeutic agents with low toxicity and good compliance should be elected. We conducted three regimens for HRPC on an outpatient basis. Eligibility criteria were defined as serial rising PSA values on 3 or more occasions at least 2 weeks apart or radiological new or extensive lesions under hormonal therapy. The first regimen is comprised of cyclophosphamide (CPM), 100 mg/day, UFT, 400 mg/day, and estramustine phosphate (EMP), 560 mg/day in two daily fractions. The second regimen is comprised of an oral administration of dexamethasone (DEX) (0.5-2 mg/day). The third regimen is comprised of DEX, 1 mg/day, cyclophosphamide, 100 mg/day and UFT, 400 mg/day in two daily fractions. Post-therapy prostate-specific antigen (PSA) level in serum, objective response on bone scan or measurable disease, and symptomatic response on bone pain were assessed. All regimens showed clinical efficacy with mild toxicity. Indications and limitations of these regimens are discussed. Further, the combination trials of taxane and EMP in patients with HRPC are reviewed.     

The comparative values of bone marrow aspirate and trephine for obtaining bone scan-targeted metastases from hormone-refractory prostate cancer

Samples of metastatic prostate cancer to bone are difficult to obtain. The aim of this study was to compare the results of bone marrow aspirate and trephine biopsy for obtaining metastatic hormone-refractory prostate cancer (HRPC) samples using previous diagnostic planar 99(m)Tc-HDP bone scans to guide the procedure. All samples taken were for the purposes of research and molecular studies on HRPC. Twenty patients with HRPC had bone marrow aspirate and trephines taken from lesions in the posterior superior iliac spine or sacro-iliac region when shown on diagnostic 99(m)Tc-HDP bone scans. Three patients also underwent plain X-ray, 18F-positron emission tomography bone scan, pelvic MRI scan and 99(m)Tc nanocolloid bone marrow scans. These images were used to assess if the extra imaging information provided, such as three-dimensional localisation of the bone metastases, was of value for target bone metastases. Cancer cells were obtained in 15/20 (75%) cases in which a trephine biopsy was attempted and 0/20 of cases in which a bone marrow aspiration was attempted. The additional information provided by the range of other imaging investigations was of little benefit in obtaining tumour samples, but did suggest why negative biopsies were obtained in some cases after targeting with planar bone scans. We recommend the use of bone marrow trephine biopsy alone, guided by previous diagnostic 99(m)Tc planar bone scan as a practical method to obtain prostate cancer cells from bone metastases.