89Strontium in bone metastases from hormone resistant prostate cancer: palliation effect and biochemical changes

Spine and Non-spine Bone Metastases - Current Controversies and Future Direction

Bone is a common site of metastases in advanced cancers. The main symptom is pain, which increases morbidity and reduces quality of life. The treatment of bone metastases needs a multidisciplinary approach, with the main aim of relieving pain and improving quality of life. Apart from systemic anticancer therapy (hormonal therapy, chemotherapy or immunotherapy), there are several therapeutic options available to achieve palliation, including analgesics, surgery, local radiotherapy, bone-seeking radioisotopes and bone-modifying agents. Long-term use of non-steroidal analgesics and opiates is associated with significant side-effects, and tachyphylaxis. Radiotherapy is effective mainly in localised disease sites. Bone-targeting radionuclides are useful in patients with multiple metastatic lesions. Bone-modifying agents are beneficial in reducing skeletal-related events. This overview focuses on the role of surgery, including minimally invasive treatments, conventional radiotherapy in spinal and non-spinal bone metastases, bone-targeting radionuclides and bone-modifying agents in achieving palliation. We present the clinical data and their associated toxicity. Recent advances are also discussed.

Single vs multiple fraction palliative radiotherapy for uncomplicated painful bone metastases treated at University of Malaya Medical Centre: A single institutional Malaysian experience

INTRODUCTION

This study was conducted to compare pain response between single and multiple fraction palliative radiotherapy and to describe prognostic factors affecting treatment response in University of Malaya Medical Centre (UMMC).

METHODS

The case records of 162 patients with uncomplicated painful bone metastases treated with palliative radiotherapy from 2006 to 2014 were analyzed. Treatment outcomes were pain score response, analgesic score response, response according to International Consensus Endpoints (complete response and overall response) at 4, 12, and 24 weeks, retreatment rate, symptomatic skeletal events (SSEs), and prognostic factors.

RESULTS

At 24 weeks, pain score response for single and multiple fraction group was 82.3% and 88.5%, analgesic score response was 54.8% and 61.5%, and overall response according to International Consensus Endpoint was 61.3% and 67.7%, respectively. There was no statistically significant difference in treatment response between the 2 treatment groups for all endpoints. ECOG (<2 vs ≥2: aOR 3.405, 95% CI 1.708-6.790, P = .001) and primary breast and prostate (breast vs others: aOR 5.231, 95% CI 1.973-13.869, P = .001; prostate vs others: aOR 5.522, 95% CI 1.493-20.420, P = .01) were significant variables on multivariate analysis.

CONCLUSION

Single fraction radiotherapy is as effective as multiple fraction radiotherapy for the palliation of uncomplicated bone metastases.

Palliative effects and adverse events of strontium-89 for prostate cancer patients with bone metastasis

The aim of the present study was to evaluate the palliative effects and adverse events of strontium-89 (Sr-89) in patients with bone metastasis from prostate cancer. A total of 18 patients with prostate cancer and painful bone metastases, as diagnosed on bone scintigraphy, who were treated with Sr-89 at the National Kyushu Cancer Center between February, 2008 and April, 2014 were reviewed. Of the 18 subjects, 13 (72.2%) achieved a pain response, whereas 5 were classified as pain non-responders (27.8%). According to a logistic regression analysis, the pre-administration characteristics, including age, prostate-specific antigen (PSA), alkaline phosphatase (ALP), history of bone-modifying agent administration, opioid use or palliative radiation therapy, time after the combined androgen blockade nadir and time since the pain onset, were not found to be significant predictors of the pain response. Similarly, the post-administration characteristics, including pain flares and the PSA and ALP response, were not found to be significant predictors of the pain response. Although no patients exhibited leukocyte toxicities, 2 patients experienced myelosuppression, involving anemia and thrombocytopenia, requiring transfusion of red cell or platelet concentrate following Sr-89 treatment. Of the 18 patients, 5 (27.8%) reported pain flares, all of whom were successfully treated with rescue drugs alone. According to the logistic regression analysis, of the pre-administration characteristics, only ALP was identified as a significant predictor of bone marrow suppression in the univariate and multivariate analyses (P=0.006). Therefore, Sr-89 treatment was found to be effective in ameliorating bone pain associated with metastasis from prostate cancer. Although it is difficult to identify the patients who will receive pain relief prior to Sr-89 administration, this drug should be administered during the early stages due to the potential for bone marrow suppression in patients with high ALP levels.

Bone-targeting radiopharmaceuticals including radium-223

Bone-seeking radionuclides including samarium-153 ethylene diamine tetramethylene phosphonate and strontium-89 have been used for decades in the palliation of pain from bone metastases especially from prostate cancer. Emerging evidence of improved survival in metastatic castration-resistant prostate cancer (CRPC) with the first-in-class α-radionuclide, radium-223 (Ra) has rekindled interest in the role of bone-seeking radionuclide therapy.We review the literature for randomized controlled trials of bone-seeking radionuclides and explore some of the issues regarding the optimal use of these agents. In particular, we discuss dose, dose rate, radiobiology, and quality of radiation and postulate on potential future directions in particular combination schedules. β-Emitting, bone-seeking radionuclides have proven ability to control pain in prostate cancer metastatic to bone with pain response rates in the order of 60% to 70% when used as single agents. Most of the published trials were underpowered to detect differences in survival; however, there is evidence of the potential for disease modification when these agents are used in combination with chemotherapy or in multiple cycles.Data from the recent phase III ALSYMPCA trial that compared Ra to placebo in symptomatic CRPC demonstrate a significant improvement in median overall survival of 3.6 months for patients with symptomatic CRPC metastatic to bone treated with 6 cycles of the α-emitting radionuclide Ra compared with placebo. The success of Ra in improving survival in CRPC will lead this agent to become part of the treatment paradigm for this disease, and with such an excellent safety profile, Ra has huge potential in combination strategies as well as for use earlier in the natural history of metastatic prostate cancer.

Hypocalcemia associated with strontium-89 administration in a patient with diffuse bone metastases from neuroendocrine carcinoma

Metastatic bone disease is often associated with severe pain in cancer patients, and has become an increasingly important quality-of-life issue. Radionuclides, such as strontium-89 (Sr-89), have provided effective palliation of metastatic bone pain. Although strontium follows the biochemical pathways of calcium in the body, changes in calcium homeostasis related to Sr-89 therapy have rarely been reported. We present a case of a 32-year-old male with poorly differentiated neuroendocrine carcinoma and extensive skeleton metastases who developed profound hypocalcemia after Sr-89 administration.

Radioisotopes for the palliation of metastatic bone cancer: a systematic review

Strontium-89 and samarium-153 are radioisotopes that are approved in the USA and Europe for the palliation of pain from metastatic bone cancer, whereas rhenium-186 and rhenium-188 are investigational. Radioisotopes are effective in providing pain relief with response rates of between 40% and 95%. Pain relief starts 1-4 weeks after the initiation of treatment, continues for up to 18 months, and is associated with a reduction in analgesic use in many patients. Thrombocytopenia and neutropenia are the most common toxic effects, but they are generally mild and reversible. Repeat doses are effective in providing pain relief in many patients. The effectiveness of radioisotopes can be greater when they are combined with chemotherapeutic agents such as cisplatin. Some studies with 89Sr and 153Sm indicate a reduction of hot spots on bone scans in up to 70% of patients, and suggest a possible tumoricidal action. Further studies are needed to address the questions of which isotope to use, what dose and schedule to use, and which patients will respond.

Targeting osseous metastases: rationale and development of radio-immunotherapy for prostate cancer

For patients with metastatic prostate cancer, bone is the primary site of tumor localization and the major cause of disease-related morbidity and mortality. Hormonal therapy and chemotherapy alone cannot eradicate disease harbored in bone. The delivery of radiotherapy to the reservoir of disease is an approach previously only achievable using bone-seeking radiopharmaceuticals. Now, however, with the identification of tumor-specific targets, antibodies are being used to deliver radiotherapy to these sites. In this article, we review the rationale behind this approach, the targets being explored, the radiation sources available, and the antibodies currently under clinical development.

Targeting osseous metastases: rationale and development of radio-immunotherapy for prostate cancer

For patients with metastatic prostate cancer, bone is the primary site of tumor localization and the major cause of disease-related morbidity and mortality. Hormonal therapy and chemotherapy alone cannot eradicate disease harbored in bone. The delivery of radiotherapy to the reservoir of disease is an approach previously only achievable using bone-seeking radiopharmaceuticals. Now, however, with the identification of tumor-specific targets, antibodies are being used to deliver radiotherapy to these sites. In this article, we review the rationale behind this approach, the targets being explored, the radiation sources available, and the antibodies currently under clinical development.

Role of strontium-89 as adjuvant to palliative external beam radiotherapy is questionable: results of a double-blind randomized study

PURPOSE

To explore the efficacy of adjuvant (89)Sr applied with external beam radiotherapy (EBRT) to treat bone metastases.

METHODS AND MATERIALS

Ninety-five patients were randomized to (89)Sr (Arm A) or saline (Arm B) on Day 1 of EBRT to demonstrate a reduction in 3-month physician-assessed subjective progression from 70% to 45%.

RESULTS

At 3 and 6 months, no difference between treatment arms was observed in the progression rate. At 3 months, the physician-assessed response rate for all patients was 25%, with 46% of the patients progressing. The pretreatment use of opiates was independently associated with short progression-free survival. On the basis of the quality-of-life assessments, pain relief occurred in 50% of patients and 32% experienced improvement in global quality of life, without impact from (89)Sr. Differences were observed between the physician evaluation of radiotherapy efficacy and the patient assessment. In Arm A, serum alkaline phosphatase, but not serum prostate-specific antigen, decreased during the first 3 months after treatment.

CONCLUSION

(89)Sr, adjuvant to ERBT, does not seem to reduce the number of patients with subjective progression at 3 months. Patients should be referred for palliative RT before their bone pain requires high doses of opiates. In radiotherapy trials, the evaluation of pain and pain relief remains problematic because of the confounding use of analgesics.

Strategies for management of prostate cancer-related bone pain

Prostate cancer is one of the most common malignancies and a leading cause of cancer-related death in men worldwide. In the majority of cases, prostate cancer metastases to the skeleton, in which case cancer-related bone pain becomes a major cause of morbidity. Androgen ablation is the treatment of choice for securing regression of skeletal metastases in the majority of cases. Intermittent androgen ablation is an attractive alternative, aimed at minimising adverse effects of hormone deprivation but also potentially delaying hormone-refractoriness. The development of hormone-refractoriness is heralded by a significant increase in morbidity largely because of escalating bone pain caused by the progression of the metastatic process. Skillful use of analgesics is initially successful but eventually fails to control symptoms. Localised metastases are best treated with local radiotherapy that is rapidly effective. Over the last few years, it has become clear that therapeutic modalities using bone-seeking radionuclides or bisphosphonates have been effective in the palliation of prostate cancer-related bone pain, although not affecting survival. The main limiting factor with the use of radionuclides is bone marrow suppression, also a feature of the very late stages of prostate cancer. Bisphosphonates do not carry this disadvantage. Results of large double-blind, placebo-controlled studies should be awaited, however, before advocating the widespread use of these agents in the management of patients with prostate cancer and skeletal metastases.

Recent advances in radionuclide therapy

A variety of radionuclides continue to be investigated and/or clinically used for different therapeutic applications in nuclear medicine. The choice of a particular radionuclide with regard to appropriate emissions, linear energy transfer, and physical half-life is dictated to a large extent by the character of the disease (eg, solid tumor or metastatic disease) and by the carrier used to selectively transport the radionuclide to the desired site. An impressive body of information has appeared in the recent literature that addresses many of these considerations. This article summarizes and discusses the many recent advances and the progress in the clinical applications of therapeutic radionuclides in relatively new and developing areas, such as radioimmunotherapy, peptide therapy, intravascular therapy to prevent restenosis, radiation synovectomy, and bone malignancy therapy. Projections are made as to the future directions and progress in these areas. The crucial issue of a reliable, year-round supply of new and emerging therapeutic radionuclides in quantities sufficient initially for research, and then for routine clinical use, is a very worthy goal which, in the United States, remains to be achieved.

The pattern of serum markers in patients with androgen-independent adenocarcinoma of the prostate

In this exploratory study, our objectives were to correlate the serum and bone marrow concentrations of putative markers of prostate cancer progression in patients with advanced androgen-independent prostate cancer (AIPC), to assess the frequency and quantity of relative expression of these markers, and to correlate the expression of the markers with extent of disease (EOD) and overall survival. In a cohort of 50 patients with AIPC with bone metastases, we obtained serum and bone marrow samples and measured prostate specific antigen (PSA), serum interleukin-6 (sIL-6), bone marrow interleukin-6, serum chromogranin A (sCgA), bone marrow chromogranin A, and prostate specific membrane antigen (PSMA) by immunoassays. EOD was determined by quantifying identifiable bone lesions on radionuclide bone scans. Each variable was categorized into two groups (low and high) based on the median found in this cohort or on the cutoff based on normal limits when available. Analyses were performed in two subsets of patients with EOD either <20 or >/=20. Results showed that: (1) PSA is associated with EOD but not with outcome; (2) sIL-6 and sCgA may be intermediate markers of early progression in AIPC, because they are predictive of outcome only in patients with EOD <20; (3) elevated PSMA is associated with elevated sIL-6 but not with PSA, suggesting that PSMA may be a useful marker in AIPC; and (4) the ratio of PSA to putative markers of progression may reflect the complex clonal progression of prostate cancer. We conclude that patients with advanced AIPC exhibit one of two patterns of serologic marker expression: in some patients the disease status is reflected by PSA, and in others it is reflected by other markers. If these data are prospectively confirmed, this would help group patients with advanced AIPC into clinically relevant categories.

Local and systemic radiation for palliation of metastatic disease

Many radiotherapeutic treatment options are available for the palliation of patients with metastatic prostate cancer. These include local field radiotherapy to symptomatic sites of metastasis and the use of radioisotope therapy either alone or in combination with local field radiotherapy. To date, the majority of patients treated with radioisotope therapy have been treated with 89Sr. Other agents, such as 153Sm-EDTMP are available now, also. Combined radioisotope therapy, cytotoxic chemotherapy, and biphosphonates hold great promise.

Overview of nuclides for bone pain palliation

A variety of radiopharmaceuticals has been used for systemic therapy to relieve pain from malignancies metastatic to bone, using electron emitting radionuclides either in ionic form or as labels for bone seeking compounds to irradiate locally at sites of metastases. The major complication comes from the absorbed dose to the bone marrow. Therefore, there has been a search for radionuclides with lower energy emissions and correspondingly shorter range in tissue. Some studies have shown that it is possible to delay the onset of new pain sites and perhaps increase life expectancy.

Serum PICP as a bone formation marker in 89Sr and external beam radiotherapy of prostatic bony metastases

The clinical management of skeletal metastatic disease is problematic because of the difficulty in treating and accurately monitoring therapy impact and disease progression. This investigation measured serum procollagen type I C-terminal peptide (PICP) concentrations as a semi-quantitative index of bone turnover in patients with metastatic prostatic adenocarcinoma before and following palliative 89Sr chloride therapy. 10 patients with early stage (stage A2, B1 and B2) biopsy-confirmed prostatic adenocarcinoma were investigated (n = 10). Two groups of 10 patients each (n = 10 per group) with advanced (stage D) metastatic prostatic adenocarcinoma who had previously undergone hormonal manipulation were also investigated. One group of patients with scintigraphically documented metastatic bone disease received additional irradiation for new symptomatic bone metastases, whereas the other group received 89Sr chloride therapy. A radioimmunoassay for PICP was used to measure serum concentrations of patients in each of these groups as well as positive and negative controls. The concentration of serum PICP rose from 649 +/- 279 before treatment with external beam radiotherapy to 927 +/- 157 ng ml-1 4 months after therapy (p < 0.05). However, the results demonstrated a four-fold decrease (p < 0.001) in serum PICP in clinical responders to 89Sr chloride therapy versus baseline 4 months after the completion of treatment. The clinical non-responders demonstrated no significant change in PICP concentrations during that interval. This may be due to an increase in untreated bony metastases in the non-89Sr treated group. Although a relatively small representative group of patients was studied, these data demonstrate that serum PICP concentration correlates with clinical response to 89Sr chloride therapy. This objective laboratory technique may be useful for monitoring and predicting the need for 89Sr chloride therapy and optimizing palliative care. It may also be extremely useful in predicting a therapeutic response to such intervention.

Unsealed source therapy of painful bone metastases: an update

Pain in patients with cancer metastatic to bone is a significant cause of morbidity and of referrals from general practice and specialist physicians. Management typically utilizes radiation therapy and the graduated use of opiate analgesics. Bone-seeking radiopharmaceuticals have provided a new option to these management strategies, which is effective and cost effective. Strontium 89 is now in routine clinical use, while rhenium 186 hydroxyethylidene diphosphonate (HEDP) and samarium 153 ethylenediaminetetramethylene phosphonate (EDTMP) are in Phase III trials and tin 117m (4+) diethylene triaminepentacetic acid (DTPA) is in Phase I trials. Evidence taken primarily from the Strontium 89 trial, shows unsealed source therapy with these bone-seeking radiopharmaceuticals to be effective in palliating pain, improving quality of life, reducing the rate at which new painful sites develop, reducing requirements for additional radiation therapy, and reducing lifetime management costs. Indications and contraindications to therapy have now been defined, and retreatment is an option with all radiopharmaceuticals.

Skeletal metastases

This synthesis of the literature on radiotherapy for skeletal metastases is based on 171 scientific articles, including 13 randomized studies, 24 prospective studies, and 79 retrospective studies. These studies involve 13054 patients. Radiotherapy has been well documented as a method for alleviating pain, but the mechanisms underlying this effect are largely unknown. When used for pain palliation, radiotherapy achieves freedom from pain, or substantial alleviation of pain in nearly all cases, with few side effects. Half-body irradiation is effective in treating multiple metastatic sites and should be considered for use more frequently. However, this increases the requirements on equipment, dosimetry, and hospital beds. Systemic radiotherapy with radionuclides may be indicated for generalized skeletal pain. The role of radiotherapy in preventing or healing fractures is not fully evaluated. Optimum dose levels and fractionation schedules have not been established. Early radiotherapy for spinal cord compression may prevent symptoms from worsening, but the effects on existing paralysis are modest.

Dose escalation study of rhenium-186 hydroxyethylidene diphosphonate in patients with metastatic prostate cancer

Rhenium-186 hydroxyethylidene diphosphonate (186Re-HEDP) has been used for the palliative treatment of metastatic bone pain. A phase 1 dose escalation study was performed using 186Re-HEDP. Twenty-four patients with hormone-resistant prostate cancer entered the study. Each patient had at least four bone metastases and adequate haematological function. Groups of at least three consecutive patients were treated with doses starting at 1295 MBq and increasing to 3515 MBq (escalated in increments of 555 MBq). Thrombocytopenia proved to be the dose-limiting toxicity, while leucopenia played a minor role. Early death occurred in one patient (10 days after administration) without clear relationship to the 186Re-HEDP therapy. Transient neurological dysfunction was seen in two cases. Two patients who received 3515 MBq 186Re-HEDP showed grade 3 toxicity (thrombocytes 25-50 x 10(9)/l), defined as unacceptable toxicity. After treatment alkaline phosphatase levels showed a transient decrease in all patients (mean: 26% +/- 10% IU/l; range: 11%-44%). Prostate-specific antigen values showed a decline in eight patients, preceded by a temporary increase in three patients. From this study we conclude that the maximally tolerated dose of 186Re-HEDP is 2960 MBq. A placebo-controlled comparative study on the efficacy of 186Re-HEDP has been initiated.

Quality of life after palliative radiotherapy in patients with hormone-resistant prostate cancer: single institution experience

OBJECTIVE

To review the development, methodology and difficulties of evaluating the quality of life (QoL) in patients with hormone-resistant prostate cancer, and to analyse the subjective effect of palliative radiotherapy among these patients.

PATIENTS AND METHODS

Since 1986, a self-administered QoL questionnaire has been developed for patients with hormone-resistant prostate cancer. The study group included 137 such patients, with a median age of 70 years (range 48-87), who received either 89Sr (31) or external beam radiotherapy (106) because of painful bone metastases. Quality of life was assessed in all patients before treatment and, if possible, 3 months afterwards.

RESULTS

The questionnaire had acceptable psychometric properties (validity, reliability). In these patients with very advanced disease, palliative radiotherapy proved less effective than reports in the literature might suggest.

CONCLUSIONS

In patients with hormone-resistant prostate cancer, quality of life assessment is both possible and desirable for the evaluation of palliative treatment. The patients' perception of physical function represents an independent prognostic factor of overall survival together with alkaline phosphatase and performance status. Valid and reliable QoL questionnaires are now available, though further research is required to establish the most effective way of using them. At 3 months palliative radiotherapy was effective in only 25% of the patients investigated, two-thirds of whom had > or = 20 hot spots on bone scan. Palliative radiotherapy should probably be offered during an earlier phase of the disease.

New bisphosphonates in the treatment of bone metastases

Normal skeletal integrity is maintained by physiological bone turnover through a coupled process of bone resorption, mediated by osteoclasts, followed by new bone formation, mediated by osteoblasts. Major features of the pathogenesis of cancer-associated skeletal destruction are enhanced osteoclast-mediated bone resorption and disruption of normal bone formation. In this article, the literature on the pathogenesis and clinical manifestations of metastatic bone disease is discussed. Animal and clinical trials investigating novel bone targeted agents, emphasizing the bisphosphonates, are critically assessed. The most frequent clinical manifestations of bone metastases are pain, fracture, immobility, spinal cord compression, and hypercalcemia. New treatments under study for patients with bone metastases include agents specifically targeted to the skeleton such as bone-seeking radioisotopes and bisphosphonates. Studies in animal models of metastatic bone disease show that these bisphosphonates are able to inhibit tumor-induced osteolysis and are potentially useful in this condition. Bisphosphonates have been investigated in several clinical trials of patients with skeletal metastases from breast cancer, prostate cancer, and multiple myeloma. Overall, the studies investigating bone targeted radioisotopes or bisphosphonates for the treatment of morbidity due to skeletal metastases have been inconclusive. An improved understanding of the pathogenesis of metastatic bone disease and preclinical studies with bisphosphonates suggest that these agents may have a role in the treatment of this disorder. Additional trials of new generation bisphosphonates, employing a rigorously controlled, randomized study design with adequate numbers of subjects, are needed to demonstrate the safety and efficacy of this class of agents in this setting.