Management of painful bone metastases

Systemic administration of Resolvin D1 reduces cancer-induced bone pain in mice: Lack of sex dependency in pain development and analgesia

AIMS

Bone cancer produces severe pain that is treated with opioids, but serious side effects limit opioid utilization. There is therefore a need to develop effective and safe non-opioid alternatives. The lipid mediator, Resolvin D1 (RvD1), could be a prospective candidate for cancer pain treatment. To assess RvD1 and other potential candidates, appropriate animal models that recapitulate clinical features must be used. Although several preclinical models of cancer pain have been developed, the influence of sex on the development of cancer pain and the effectiveness of RvD1 have not been studied.

RESULTS

Using a mouse model of fibrosarcoma growth in and around the calcaneus bone, we demonstrated that the mechanical hyperalgesia in the tumor-bearing hind paw develops independently of sex, except that it developed a little sooner in female mice. A single intravenous injection of RvD1 (0.001-10 μg/kg) decreased hyperalgesia in both sexes with similar potency (ED50 = 0.0015 μg/kg) and efficacy. Repeated daily administration of 10 μg/kg RvD1 prolonged the analgesic effect and completely abolished hyperalgesia. This was also independent of sex.

CONCLUSION

In this preclinical mouse model of bone cancer pain, the development of pain and the analgesic effectiveness of RvD1 are not influenced by sex.

Treatment of Pelvic and Spinal Bone Metastases: Radiotherapy and Hyperthermia Alone vs. in Combination

Painful pelvic and spinal bone metastases are a considerable challenge for doctors and patients. Conventional therapies include morphine-equivalent medication (MeM) and local radiotherapy (RT), but these interventions are not always successful. More recently, hyperthermia (HT) has been applied to complement RT and MeM, and this complex approach has shown promising synergistic results. The objective of our study was to present the results of RT combined with a special kind of HT (modulated electrohyperthermia, mEHT), in which some of the thermal effect is contributed by equivalent nonthermal components, drastically reducing the necessary power and energy. This retrospective study included 61 patients divided into three groups with pelvic and spinal bone metastases to compare the effects of RT and mEHT alone and in combination (RT + mEHT). A detailed evaluation of pain intensity, measured by the brief pain inventory score, MeM use, and breakthrough pain episodes, revealed no significant differences between RT and mEHT alone; thus, these individual methods were considered equivalent. However, RT + mEHT yielded significantly better results in terms of the above parameters. Clinically, mEHT has a lower risk of adverse thermal effects, and due to its efficacy, mEHT can be used to treat RT-resistant lesions.

Magnetic resonance-guided focused ultrasound versus percutaneous thermal ablation in local control of bone oligometastases: a systematic review and meta-analysis

BACKGROUND

The percutaneous thermal ablation techniques (pTA) are radiofrequency ablation, cryoablation, and microwave ablation, suitable for the treatment of bone oligometastases. Magnetic resonance-guided focused ultrasound (MRgFUS) is a noninvasive ablation technique.

OBJECTIVES

To compare the effectiveness and safety of MRgFUS and pTA for treating bone oligometastases and their complications.

METHODS

Studies were selected with a PICO/PRISMA protocol: pTA or MRgFUS in patients with bone oligometastases; non-exclusive curative treatment. Exclusion criteria were: primary bone tumor; concurrent radiation therapy; palliative therapy; and absence of imaging at follow-up. PubMed, BioMed Central, and Scopus were searched. The modified Newcastle-Ottawa Scale assessed articles quality. For each treatment (pTA and MRgFUS), we conducted two separate random-effects meta-analyses to estimate the pooled effectiveness and safety. The effectiveness was assessed by combining the proportions of treated lesions achieving local tumor control (LTC); the safety by combining the complications rates of treated patients. Meta-regression analyses were performed to identify any outcome predictor.

RESULTS

A total of 24 articles were included. Pooled LTC rate for MRgFUS was 84% (N = 7, 95% CI 66-97%, I2 = 74.7%) compared to 65% of pTA (N = 17, 95% CI 51-78%, I2 = 89.3%). Pooled complications rate was similar, respectively, 13% (95% CI 1-32%, I2 = 81.0%) for MRgFUS and 12% (95% CI 8-18%, I2 = 39.9%) for pTA, but major complications were recorded with pTA only. The meta-regression analyses, including technique type, study design, tumor, and follow-up, found no significant predictors.

DISCUSSION

The effectiveness and safety of the two techniques were found comparable, even though MRgFUS is a noninvasive treatment that did not cause any major complication. Limited data availability on MRgFUS and the lack of direct comparisons with pTA may affect these findings.

CONCLUSIONS

MRgFUS can be a valid, safe, and noninvasive treatment for bone oligometastases. Direct comparison studies are needed to confirm its promising benefits.

Pain Outcomes in Patients with Metastatic Castration-Resistant Prostate Cancer Treated with 223Ra: PARABO, a Prospective, Noninterventional Study

223Ra, a targeted α-therapy, is approved for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) who have bone metastases. In the phase 3 ALSYMPCA study, 223Ra prolonged survival and improved quality of life versus placebo. Our real-world study, PARABO, investigated pain and bone pain-related quality of life in patients with mCRPC and symptomatic bone metastases receiving 223Ra in clinical practice. Methods: PARABO was a prospective, observational, noninterventional single-arm study conducted in nuclear medicine centers across Germany (NCT02398526). The primary endpoint was a clinically meaningful pain response (≥2-point improvement from baseline for the worst-pain item score in the Brief Pain Inventory-Short Form). Results: The analysis included 354 patients, who received a median of 6 223Ra injections (range, 1-6). Sixty-seven percent (236/354) received 5-6 injections, and 33% (118/354) received 1-4 injections. Of 216 patients with a baseline worst-pain score of more than 1, 59% (128) had a clinically meaningful pain response during treatment. Corresponding rates were 67% (range, 98/146) with 5-6 223Ra injections versus 43% (range, 30/70) with 1-4 injections, 60% (range, 60/100) in patients with no more than 20 lesions versus 59% (range, 65/111) in those with more than 20 lesions, and 65% (range, 69/106) in patients without prior or concomitant opioid use versus 54% (range, 59/110) in those with prior or concomitant opioid use. Mean subscale scores (pain severity and pain interference) on the Brief Pain Inventory-Short Form improved during treatment. Conclusion: 223Ra reduced pain in patients with mCRPC and symptomatic bone metastases, particularly in patients who received 5-6 injections. The extent of metastatic disease did not impact pain response.

Mechanisms of cancer pain

Personalised and targeted interventions have revolutionised cancer treatment and dramatically improved survival rates in recent decades. Nonetheless, effective pain management remains a problem for patients diagnosed with cancer, who continue to suffer from the painful side effects of cancer itself, as well as treatments for the disease. This problem of cancer pain will continue to grow with an ageing population and the rapid advent of more effective therapeutics to treat the disease. Current pain management guidelines from the World Health Organisation are generalised for different pain severities, but fail to address the heterogeneity of mechanisms in patients with varying cancer types, stages of disease and treatment plans. Pain is the most common complaint leading to emergency unit visits by patients with cancer and over one-third of patients that have been diagnosed with cancer will experience under-treated pain. This review summarises preclinical models of cancer pain states, with a particular focus on cancer-induced bone pain and chemotherapy-associated pain. We provide an overview of how preclinical models can recapitulate aspects of pain and sensory dysfunction that is observed in patients with persistent cancer-induced bone pain or neuropathic pain following chemotherapy. Peripheral and central nervous system mechanisms of cancer pain are discussed, along with key cellular and molecular mediators that have been highlighted in animal models of cancer pain. These include interactions between neuronal cells, cancer cells and non-neuronal cells in the tumour microenvironment. Therapeutic targets beyond opioid-based management are reviewed for the treatment of cancer pain.

Rac1/PAK1 signaling contributes to bone cancer pain by Regulation dendritic spine remodeling in rats

Bone cancer pain (BCP) is severe chronic pain caused by tumor metastasis to the bones, often resulting in significant skeletal remodeling and fractures. Currently, there is no curative treatment. Therefore, insight into the underlying mechanisms could guide the development of mechanism-based therapeutic strategies for BCP. We speculated that Rac1/PAK1 signaling plays a critical role in the development of BCP. Tumor cells implantation (TCI) into the tibial cavity resulted in bone cancer-associated mechanical allodynia. Golgi staining revealed changes in the excitatory synaptic structure of WDR (Wide-dynamic range) neurons in the spinal cord, including increased postsynaptic density (PSD) length and thickness, and width of the cleft. Behavioral and western blotting test revealed that the development and persistence of pain correlated with Rac1/PAK1 signaling activation in primary sensory neurons. Intrathecal injection of NSC23766, a Rac1 inhibitor, reduced the persistence of BCP as well as reversed the remodeling of dendrites. Therefore, we concluded that activation of the Rac1/PAK1 signaling pathway in the spinal cord plays an important role in the development of BCP through remodeling of dendritic spines. Modulation of the Rac1/PAK1 pathway may be a potential strategy for BCP treatment.

Dexamethasone Coanalgesic Administration in Steroid Naïve and Steroid Non-Naïve Patients for the Prevention of Pain Flares after Palliative Radiotherapy for Bone Metastases

Objective

Dexamethasone could be an effective prophylactic agent for the prevention of pain flares after palliative radiotherapy (RT) for uncomplicated bone metastases. To date, there are no data on its prophylactic coanalgesic (opioid-sparing) effect after RT in patients with complicated bone metastases compared to uncomplicated ones, which is the aim of our study.

Methods

Twenty-nine American Society of Anaesthesiologists (ASA) III-IV patients, aged ≥18, treated with single-fraction 8 Gy/1 or multi-fraction 20 Gy/5 RT for painful uncomplicated bone metastases (steroid naïve patients, n = 14) or complicated ones (steroid non-naïve patients, n = 15), were examined retrospectively. All patients received parenteral dexamethasone (4 mg or 8 mg daily, 1 hour before RT, followed by the same dose for the next 4 days) along with their background and breakthrough pain opioid intake (morphine equivalents) during their 5-day in-hospital stay. Pain severity (numeric rating scale) and analgesic consumption were recorded at admission, daily during the hospital stay, and for 10 days following treatment. Binary logistic regression was used to determine predictive factors for pain flare occurrence.

Results

A higher ASA score is the only determinant positively influencing opioid consumption (P = 0.018) and pain flare as well (OR = 15.00; 95% CI: 2, 24-100, 48; P = 0.005). Lower dose 4 mg dexamethasone was revealed as a moderate analgesic agent in steroid naïve patients with no side effects, whereas in steroid non-naïve patients the predominantly higher dose 8 mg dexamethasone had minimal impact on pain flares prevention at the expense of more pronounced immunosuppression (P = 0.039).

Conclusions

Irrespective of the supporting evidence of dexamethasone potential for prevention of RT-induced pain flare, our data failed to reveal its efficacy in the real practice world (a case mix of uncomplicated and complicated bone metastases). Further dose-effect bigger studies are needed, identifying optimal doses of dexamethasone intake and its optimal duration in high-risk patients.

Interventional Radiology in the Management of Metastases and Bone Tumors

Interventional Radiology (IR) has experienced an exponential growth in recent years. Technological advances of the last decades have made it possible to use new treatments on a larger scale, with good results in terms of safety and effectiveness. In musculoskeletal field, painful bone metastases are the most common target of IR palliative treatments; however, in selected cases of bone metastases, IR may play a curative role, also in combination with other techniques (surgery, radiation and oncology therapies, etc.). Primary malignant bone tumors are extremely rare compared with secondary bone lesions: osteosarcoma, Ewing sarcoma, and chondrosarcoma are the most common; however, the role of interventional radiology in this fiels is marginal. In this review, the main techniques used in interventional radiology were examined, and advantages and limitations illustrated. Techniques of ablation (Radiofrequency, Microwaves, Cryoablation as also magnetic resonance imaging-guided high-intensity focused ultrasound), embolization, and Cementoplasty will be described. The techniques of ablation work by destruction of pathological tissue by thermal energy (by an increase of temperature up to 90 °C with the exception of the Cryoablation that works by freezing the tissue up to -40 °C). Embolization creates an ischemic necrosis by the occlusion of the arterial vessels that feed the tumor. Finally, cementoplasty has the aim of strengthening bone segment weakened by the growth of pathological tissue through the injection of cement. The results of the treatments performed so far were also assessed and presented focused the attention on the management of bone metastasis.

Musculoskeletal Applications of Magnetic Resonance-Guided Focused Ultrasound

Magnetic resonance-guided focused ultrasound (MRgFUS) is a novel noninvasive therapy that uses focused sound energy to thermally ablate focal pathology within the body. In the United States, MRgFUS is approved by the Food and Drug Administration for the treatment of uterine fibroids, palliation of painful bone metastases, and thalamotomy for the treatment of essential tremor. However, it has also demonstrated utility for the treatment of a wide range of additional musculoskeletal (MSK) conditions that currently are treated as off-label indications. Advantages of the technology include the lack of ionizing radiation, the completely noninvasive technique, and the precise targeting that offer unprecedented control of the delivery of the thermal dose, as well as real-time monitoring capability with MR thermometry. In this review, we describe the most common MSK applications of MRgFUS: palliation of bone metastases, treatment of osteoid osteomas, desmoid tumors, facet arthropathy, and other developing indications.

Efficacy and safety of magnetic resonance-guided focused ultrasound for the treatment of painful bone metastases: a systematic review and meta-analysis

OBJECTIVE

To report the safety and efficacy of magnetic resonance-guided focused ultrasound (MRgFUS) in the treatment of painful bone metastases through a systematic review and meta-analysis of pain scores before and after MRgFUS treatment and post-treatment adverse events.

MATERIALS AND METHODS

A comprehensive literature search of PubMed and Embase databases was performed for studies evaluating the efficacy and/or safety of MRgFUS. The mean difference of pain scores (10-point visual analogue scale or numerical rating scale) between baseline and 1-month/3-month pain scores was collected and analyzed in a pooled meta-analysis. Post-treatment adverse events based on the Common Terminology Criteria for Adverse Events (CTCAE) grading were recorded and the pooled prevalence was calculated.

RESULTS

A total of 33 studies published between 2007 and 2019 were collected, resulting in a total sample size of 1082 patients. The majority of the studies were prospective with a reported follow-up period of 3 months. The pooled proportion of patients that achieved pain relief from MRgFUS (complete response or partial response [≥ 2-point improvement of pain score]) was 79% (95% CI 73-83%). The pooled 1-month and 3-month mean difference in pain score were - 3.8 (95% CI - 4.3; - 3.3) and - 4.4 (95% CI - 5.0; - 3.7), respectively. The overall rate of high-grade (CTCAE grade 3 or higher) and low-grade (CTCAE grade 2 or lower) MRgFUS-related adverse events were 0.9% and 5.9%, respectively.

CONCLUSION

MRgFUS is an effective procedure that is able to provide significant pain palliation for patients with symptomatic bone metastases with a favorable safety profile.

Mechanisms, Diagnosis and Treatment of Bone Metastases

Bone and bone marrow are among the most frequent metastatic sites of cancer. The occurrence of bone metastasis is frequently associated with a dismal disease outcome. The prevention and therapy of bone metastases is a priority in the treatment of cancer patients. However, current therapeutic options for patients with bone metastatic disease are limited in efficacy and associated with increased morbidity. Therefore, most current therapies are mainly palliative in nature. A better understanding of the underlying molecular pathways of the bone metastatic process is warranted to develop novel, well-tolerated and more successful treatments for a significant improvement of patients' quality of life and disease outcome. In this review, we provide comparative mechanistic insights into the bone metastatic process of various solid tumors, including pediatric cancers. We also highlight current and innovative approaches to biologically targeted therapy and immunotherapy. In particular, we discuss the role of the bone marrow microenvironment in the attraction, homing, dormancy and outgrowth of metastatic tumor cells and the ensuing therapeutic implications. Multiple signaling pathways have been described to contribute to metastatic spread to the bone of specific cancer entities, with most knowledge derived from the study of breast and prostate cancer. However, it is likely that similar mechanisms are involved in different types of cancer, including multiple myeloma, primary bone sarcomas and neuroblastoma. The metastatic rate-limiting interaction of tumor cells with the various cellular and noncellular components of the bone-marrow niche provides attractive therapeutic targets, which are already partially exploited by novel promising immunotherapies.

Dorsal root ganglia NR2B-mediated Epac1-Piezo2 signaling pathway contributes to mechanical allodynia of bone cancer pain

Mechanical allodynia is a painful perception of mechanical stimuli and one of the typical symptoms in bone cancer pain (BCP). Previous studies have revealed that mice and humans lacking mechanically activated Piezo2 channels do not sense mechanical stimuli. However, the underlying mechanism of Piezo2 in BCP has not been well established. The aim of the present study was to investigate whether exchange protein directly activated by cAMP 1 (Epac1) mediated Piezo2 signaling pathway may be responsible for the mechanical allodynia of BCP and whether N-methyl-D-aspartic acid (NMDA) receptor subunit 2B (NR2B) is involved in the pathway. In the present study, a BCP model was established in C3H/HeJ mice by intramedullary injection of osteosarcoma cells. The results of the mechanical allodynia test demonstrated a markedly decreased paw withdrawal mechanical threshold in BCP mice, accompanied by a significant increase in Epac1, NR2B proteins and Piezo2 mRNA expression levels in the ipsilateral dorsal root ganglion (DRG). Compared with the sham group, intrathecal Epac1 antisense oligodeoxynucleotides (Epac1-ASODN) effectively ameliorated the mechanical allodynia and decreased the expression levels of NR2B and Piezo2 in the tumor group. Pretreatment of naïve mice with a NR2B antagonist prevented the aggravation of mechanical allodynia and DRG Piezo2 levels induced by an Epac1 agonist. However, the NR2B agonist-induced increase in Piezo2 expression levels was not reversed by pretreatment with Epac1-ASODN. In conclusion, the results of the present study demonstrated that NR2B, which is a crucial downstream regulator of Epac1, may mediate the Epac1-Piezo2 pathway contributing to the development of the mechanical allodynia of BCP. The present study may enrich the theoretical knowledge of the mechanical allodynia of BCP and provide a potential analgesic strategy for clinical treatment.

Scorpion alleviates bone cancer pain through inhibition of bone destruction and glia activation

Background

Bone cancer pain is common in patients with advanced cancers as tumor metastasizes to bone. The inefficient clinical treatment severely reduces quality of life of bone cancer pain patients. During the pain status, activated spinal astrocytes and microglia release various inflammatory cytokines, resulting in spinal inflammation and the development of neuron sensitization. Scorpion is the dry body of Buthus martensii Karsch and is often used for various pain management in clinical practice. However, its function on bone cancer pain is unclear.

Methods

We investigated the effects of intragastric administration of scorpion on bone cancer pain induced by left tibial cavity injection of Walker 256 cells. Nociceptive behavior was measured using the von Frey filaments test and the spontaneous ambulatory pain score. The bone destruction was assessed by tibial radiographs. Expression of spinal cord astrocyte marker glial fibrillary acidic protein and microglial marker Iba1 was monitored by Western blot assay and immunofluorescence. Tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and IL-1β was detected by real-time polymerase chain reaction. The proliferation of Walker 256 cells was evaluated by CCK8 assay.

Results

Intragastric administration of scorpion reduced bone cancer pain behavior and relieved bone destruction, accompanied by decreased expression of spinal glial fibrillary acidic protein and Iba1 protein level and TNF-α, IL-6, and IL-1β mRNA level. Besides, scorpion inhibited proliferation of Walker 256 cells in a dose- and time-dependent manner.

Conclusion

Our results demonstrate that scorpion produces an analgesic effect in a rat model of bone cancer pain via inhibiting bone destruction and activation of spinal cord astrocytes and microglia.

Pre-radiotherapy pain intensity and health-related quality of life in patients with bone metastases at various vertebral levels

PURPOSE

The spine is the most common site of bone metastasis from cancer and can be divided into 5 locational subsections, varying in mobility. The purpose of this research was to determine if the mobility of the metastases-bearing vertebral segment influenced pre-treatment pain intensity or health-related quality of life (HR-QoL) for patients about to receive palliative radiation therapy for painful spine metastasis.

METHODS

This study was a retrospective chart review of patients referred to the Palliative Radiation Oncology Program, about to receive radiation therapy for vertebral metastasis between January 2014 and June 2016. The main variables included patient-reported Edmonton Symptom Assessment Score pain intensity, the EQ-5D score for HR-QoL and the location of the vertebral metastasis (categorized using the SINS mobility score (mobile, junctional, semi-rigid, or rigid)). Various patient, disease and treatment characteristics were also collected, and entered into a multivariate analysis.

RESULTS

The eligible sample included 196 patients. Spinal metastases were distributed with approximately equal frequency (~27%) between the junctional, mobile and semi-rigid spine segments. Rigid spine was the least common site for spinal metastases (19%). Patients with metastatic disease in the mobile spine regions experienced greater pre-treatment pain compared to patients with disease in junctional subsections (Odds Ratio [OR] 1.37; p0.012). No relationship between HR-QOL and spinal mobility was found. Multivariate analysis also revealed that spinal metastases from a primary lung diagnosis reported worse pre-treatment pain compared to those from genitourinary cancers (OR 1.15; p0.05). Only age significantly influenced HR-QoL (75-95yrs vs. 35-55yrs; p0.041).

CONCLUSIONS

Patients referred to an RT clinic for the treatment of painful spinal metastases have a different distribution of disease throughout the spine compared to those referred for surgery or SBRT. Those with metastases in mobile spine segments were more likely to experience severe pre-treatment pain than those with metastases in junctional segments. Although further corroboration is needed, our results suggest that the mobility of the metastasis-bearing spinal section could be added to the existing list of predictors that aid clinicians in identifying patients that will benefit from closer follow-up or early intervention.

Radiopharmaceutical therapy in cancer: clinical advances and challenges

Radiopharmaceutical therapy (RPT) is emerging as a safe and effective targeted approach to treating many types of cancer. In RPT, radiation is systemically or locally delivered using pharmaceuticals that either bind preferentially to cancer cells or accumulate by physiological mechanisms. Almost all radionuclides used in RPT emit photons that can be imaged, enabling non-invasive visualization of the biodistribution of the therapeutic agent. Compared with almost all other systemic cancer treatment options, RPT has shown efficacy with minimal toxicity. With the recent FDA approval of several RPT agents, the remarkable potential of this treatment is now being recognized. This Review covers the fundamental properties, clinical development and associated challenges of RPT.

The Endocannabinoid System Alleviates Pain in a Murine Model of Cancer-Induced Bone Pain

Metastatic breast cancer is prevalent worldwide, and one of the most common sites of metastasis is long bones. Of patients with disease, the major symptom is pain, yet current medications fail to adequately result in analgesic efficacy and present major undesirable adverse effects. In our study, we investigate the potential of a novel monoacylglycerol lipase (MAGL) inhibitor, MJN110, in a murine model of cancer-induced bone pain. Literature has previously demonstrated that MAGL inhibitors function to increase the endogenous concentrations of 2-arachydonylglycerol, which then activates CB1 and CB2 receptors to inhibit inflammation and pain. We demonstrate that administration of MJN110 significantly and dose dependently alleviates spontaneous pain behavior during acute administration compared with vehicle control. In addition, MJN110 maintains its efficacy in a chronic-dosing paradigm over the course of 7 days without signs of receptor sensitization. In vitro analysis of MJN110 demonstrated a dose-dependent and significant decrease in cell viability and proliferation of 66.1 breast adenocarcinoma cells to a greater extent than KML29, an alternate MAGL inhibitor, or the CB2 agonist JWH015. Chronic administration of the compound did not appear to affect tumor burden, as evidenced by radiograph or histologic analysis. Together, these data support the application for MJN110 as a novel therapeutic for cancer-induced bone pain. SIGNIFICANCE STATEMENT: Current standard of care for metastatic breast cancer pain is opioid-based therapies with adjunctive chemotherapy, which have highly addictive and other deleterious side effects. The need for effective, non-opioid-based therapies is essential, and harnessing the endogenous cannabinoid system is proving to be a new target to treat various types of pain conditions. We present a novel drug targeting the endogenous cannabinoid system that is effective at reducing pain in a mouse model of metastatic breast cancer to bone.

Baicalin Ameliorates Bone Cancer Pain by Suppressing TRPV1 in Rat Dorsal Root Ganglia

Bone cancer pain is characterized by moderate to severe ongoing pain that commonly requires the use of opiates, which could produce tolerance or addiction. Baicalin is a flavonoid compound extracted from Huang Qin, possesses antioxidant properties, and has an analgesic effect on nitroglycerin-induced migraine in rats and neuropathic pain in spinal nerve ligation rats. However, the effect of baicalin on bone cancer pain is still unclear. Therefore, the aim of this study is to examine the analgesic effect of baicalin in a rat model of bone cancer pain. Bone cancer pain animal model was created by tumor cell implantation (TCI). Animal behaviors were measured using a set of mechanical or electronic von Frey apparatus and hot plate. mRNA expression and inflammation cytokine levels were examined by Quantitative polymerase chain reaction (qPCR) and enzyme linked immunosorbent assay (ELISA) methods. Baicalin suppressed the upregulation of transient receptor potential vanilloid 1 (TRPV1), but not transient receptor potential A1 in dorsal root ganglion (DRG) of TCI rats. In addition, the phosphorylation of extracellular regulated protein kinases (ERK) was also suppressed by baicalin injection in DRG of TCI rats. Our results revealed that baicalin might play a promising analgesic role by preventing the upregulation of TRPV1 in DRG of TCI rats. Baicalin administration prevented the progress of bone cancer pain and reduced mechanical allodynia and thermal hyperalgesia. Our study clearly established a novel role of baicalin as an analgesic agent for bone cancer pain. And the analgesic role of baicalin in bone cancer pain might involve a TRPV1.

Macrofluidic recirculating model of skeletal metastasis

While microfluidic systems model aspects of metastasis, they are limited to artificially created tissues of limited complexity. We set out to develop an in vitro model of tumor cell migration from a primary tumor to a distant site that allows use of tissue. Accordingly, we created a macrofluidic model using culture plate wells connected with type I collagen-coated large bore tubing and has recirculating media. Green fluorescent protein-positive prostate carcinoma cells in a hydrogel or excised tumor xenografts from mice were placed into primary tumor sites and either human bone stromal cells (HS-5) in a hydrogel or human-derived bone chips were seeded into metastatic sites. Cells from the primary sites migrated to and grew in metastatic sites. Bone enhanced growth at metastatic sites and established a CXCL12 gradient that was higher in metastatic versus primary sites. AMD3100-mediated inhibition of CXCL12 function reduced the number of cells targeting the bone at the metastatic sites. In summary, we have developed a macrofluidic metastasis model that allows incorporation of tumor and metastatic microenvironment tissues and models chemotaxis. This system allows for incorporation of tumor heterogeneity and inclusion of an intact microenvironment. These features will facilitate identification of mechanisms and therapeutics for bone metastasis.

Symptom Palliation in Patients with Bone Metastases Treated with Radiotherapy

Context: Skeleton is the most common organ affected by metastases. Bone pain is the most common symptom of metastatic bone disease. The treatment of bone metastasis is primarily palliative requiring multidisciplinary therapies; radiotherapy (RT), however, remains the cornerstone of the treatment. Aims: The aim of this study is to measure the effectiveness of RT in terms of symptomatic relief in pain and insomnia, improvement in stability/movement, and decrease in the requirement of analgesics by patients using the Hundred Paisa Pain Scale. Subjects and Methods: The RT records of 226 patients with bone metastasis treated at the department of Radiotherapy, SMS Medical College, Jaipur; from July 2015 to December 2016 over cobalt-60 teletherapy unit were analyzed. The RT dose fractionation ranged from 30 Gy in 10 daily fractions, 20 Gy in 5 daily fractions, 12.5 Gy in 2 weekly fractions, and 8 Gy in single fraction. Results: The median age of the cohort was 54 (range, 29–84) years. The most common site of primary tumor was lung (30.1%), followed by breast (12.4%) and prostate (11.9%). The most common bone involved was vertebrae (71.2%), followed by pelvis (14.6%); among vertebrae, thoracic vertebrae were most commonly involved (63.9%), followed by lumbar vertebrae (57.8%). The maximum relief in pain was seen with 6.25 Gy/fraction schedule, whereas the maximum improvement in stability/movement was noted with 3 Gy/fraction schedule. The 8 Gy single-fraction schedule was associated with maximum relief in insomnia and decrease in analgesic requirement. Conclusion: The current institutional protocol of weekly hypofractionated palliative RT of 6.25 Gy per fraction up to a maximum of four fractions given on Saturday has shown results comparable with other schedules with well tolerance and achievement of acceptable symptom palliation. This weekly schedule is practically convenient to both the patients who mostly came from far-flung areas and the institute as it spares the already overburdened machine to carry on conventional RT from Monday to Friday.

Thalidomide alleviates bone cancer pain by down-regulating expressions of NF-κB and GFAP in spinal astrocytes in a mouse model

Aim: Thalidomide is one of the first line therapies in cancer pain management. Previous study has shown that thalidomide decreases the expression of tumor necrosis factor alpha in the mouse spinal cord. However, the exact cellular and molecular mechanism underlying the effect of thalidomide remains unclear. Here, we investigated the effect of thalidomide on the expression level of NF-κB as well as glial fibrillary acidic protein (GFAP) in the spinal cord astrocyte in a mice model. Materials and methods: MC57G fibrosarcoma cells were intramedullary injected into the right femurs of C57/BL mice to induce behaviors related to bone cancer pain. Postoperative thalidomide was administered intraperitoneally to the mice at dose of 100 mg/kg/day for 7 days. The effect of thalidomide on pain hypersensitivity was checked by behavioral testing. The expression levels of NF-κB and GFAP in spinal cord were evaluated by using Western blotting and Immunohistochemistry. Results: Compared with the controls, the tumor-bearing mice showed substantial pain-related behaviors. Furthermore, the expression levels of both NF-κB and GFAP increased significantly in the spinal cord astrocytes of the tumor-bearing mice. Treating the tumor-bearing mice with thalidomide results in a dramatic reduction in pain behaviors and a significant decrease of NF-κB and GFAP expressions. Conclusions: Thalidomide alleviates the pain behaviors probably by down-regulating the expression of NF-κB and GFAP.

Preliminary results: use of multi-hole injection nails for intramedullary nailing with simultaneous bone cement injection in long-bone metastasis

OBJECTIVE

For symptomatic metastasis of the long bones, intramedullary nailing has been the most accepted fixation method. Intramedullary nailing has effective control of pain, perioperative bleeding, and local tumor progression by augmentation with bone cement around the nail. Here, we report the preliminary results of a new surgical implant that allows for simultaneous injection of bone cement while inserting a percutaneous, flexible intramedullary nail.

MATERIALS AND METHODS

We performed palliative surgeries for long-bone metastasis using a multi-hole injection nail (MIN) with multiple side holes in the distal one third. When the nail tip entered the metastatic cancer lesion, the bone cement injection was started, and continued until the nail was completely seated. Ten patients with advanced cancer underwent palliative surgery using the new implant with simultaneous bone cement injection for humeral (n = 4), femoral (n = 4), and tibial (n = 2) metastases.

RESULTS

The mean operative time was 42 min (range, 36-52 min). The mean length of the injection nail was 23.0 cm (range, 18.0-33.0 cm), and the mean volume of cement was 28.0 ml (range, 14.0-40.0 ml). Marked pain palliation (p < 0.001) and functional recovery (p = 0.01) were verified. The mean Musculoskeletal Tumor Society (MSTS) functional score improved significantly from 12.5 at 6 weeks preoperatively, to 24.9 postoperatively. No acute postoperative complications, including cement embolism, occurred.

CONCLUSION

This minimally invasive surgical method with MIN could be useful for stabilization of long-bone metastases in patients with advanced cancer.

The history of cancer pain and bone-targeted agents: 10 most commonly asked questions

The prevalence of pain and skeletal complications of metastatic bone disease is high and an important factor, which contributes to decreased quality of life and low survival rate. Bone-targeted agents are well-established therapies to reduce the skeletal-related events in patients with bone metastasis. However, the analgesic effect of these medications is still controversial. The objective of this review is to summarize the existing evidence about the use of bone-targeted agents in the treatment of metastatic bone pain, trying to answer to the 10 most commonly asked questions in this matter. To achieve this goal, authors did a research of reviews published between January 2001 and January 2018, using the terms MeSH: “cancer pain” and bisphosphonates. The source used was the PubMed (NLM) database. The search yielded 36 reviews, but only 16 met the inclusion criteria. Even with the introduction of a new class of drugs, bisphosphonates and specially zoledronic acid are the most commonly used drugs in most oncology centers. Bisphosphonates and denosumab appear to be beneficial in preventing skeletal morbidity but their analgesic role and impact on quality of life and survival are not so well established.

Palliative care: needs of advanced breast cancer patients

Advanced breast cancer is characterized by many physical manifestations with the potential to undermine the quality of life (most related to the cancer and some to treatments), as well as substantial impact on psychosocial well-being. Patients with advanced breast cancer and their families have complex needs that have to be addressed in order to minimize severe distress and deterioration in the quality of life of patients and their family members. This task requires the full engagement of an interdisciplinary approach to palliative care with strong emphasis on the assessment of needs and anticipated needs, patient expectations, skilled therapeutics, and commitment to continuity of care. In this review, we address four issues: 1) organizational and conceptual issues in palliative care of patients with breast cancer, 2) common physical symptoms among patients with breast cancer and their management, 3) common psychological issues among patients with breast cancer, and 4) common challenging palliative care problems in breast cancer.

Rhenium-188 Hydroxyethane 1,1-Diphosphonic Acid (HEDP) for Bone Pain Palliation Using BARC-HEDP Kits versus Pars-HEDP Kits: A Comparison on Preparation and Performance Aspects at Hospital Radiopharmacy

Purpose of the Study:

Rhenium-188 hydroxyethane 1,1-diphosphonic acid (HEDP) is a clinically established radiopharmaceutical for palliation of bone pain due to osseous metastases. Recently, the Bhabha Atomic Research Centre (BARC) had developed a freeze-dried kit for the preparation of rhenium-188 HEDP. The present study compares the radiochemistry aspects of indigenous BARC-HEDP kits with commercially available HEDP kits from Pars Isotope Company, Iran.

Materials and Methods:

Freeze-dried HEDP kits were obtained from Radiopharmaceuticals Division, BARC, and Pars Isotope Company, Iran. Following recommended procedures, rhenium-188 HEDP was prepared using freeze-dried kits from both sources using freshly eluted rhenium-188 sodium perrhenate obtained from a commercial tungsten-188/rhenium-188 generator.

Results:

Both kits could be used for the preparation of rhenium-188 HEDP in >95% radiochemical purity (RCP). Rhenium-188 HEDP prepared from both kits showed comparable in vitro stability as well as pharmacokinetic properties. The normal bone-to-soft tissue ratio observed for rhenium-188 HEDP prepared using BARC-HEDP kit and Pars-HEDP kit was 1.993 and 1.416, respectively.

Conclusions:

Both HEDP kits provided a user-friendly solution for the preparation of rhenium-188 HEDP. While Pars-HEDP-kit permits the addition of only 2 mL of rhenium-188 perrhenate solution per kit vial, BARC-HEDP-kit allows up to 5 mL. This feature permits the preparation of patient dose of rhenium-188 HEDP even with older generators providing rhenium-188 perrhenate having a low radioactive concentration (activity/mL). In addition, availability of an indigenous product is always preferable over imported options.

Pain flare, complexity and analgesia in bone oligometastases treated with stereotactic body radiation therapy

The aim of our study was to assess the incidence of pain flare and the effectiveness of stereotactic body radiotherapy (SBRT) in pain management of patients with bone oligometastases. We evaluated 48 patients accounting for 54 treatments. The Edmonton Classification System for Cancer Pain (ECS-CP) was applied to identify indicators of treatment-resistant pain, in patients with active pain (NRS ≥ 2) at baseline. Statistical analysis was performed to identify predictors of pain flare and pain control. Pain flare occurred in 38% of treated patients (n = 18/48): No correlation was found between pain flare and patient- or treatment-related variables. In the subset of patients with active pain at baseline (n = 23), pain control was obtained in 62% of patients at 1 year; median time to pain progression after SBRT was 29 months (CI95% 6-52 months). Presence of ≥2ECS-CP features was correlated with earlier pain progression (4 vs. 30 months, p = 0.012). Pain flare occurred in 38% of cases irrespectively of steroid premedication and dose regimen. In patient with baseline active pain, durable pain control was obtained. Presence of ≥2 complexity indicators at the ECS-CP assessment was correlated with impaired pain control and may deserve future investigation in prospective studies.

Joint-preserving palliative surgery using self-locking screws of intramedullary nail and percutaneous cementoplasty for proximal humeral metastasis in the advanced cancer patients

BACKGROUND

We introduced a palliative joint-preserving surgery using proximal self-locking screws of intramedullary (IM) nail and percutaneous cementoplasty (PC) in patients with proximal humeral metastases, including the head and neck, and evaluated the outcome of the surgical method.

METHODS

Twenty-three patients (mean age = 63.0 ± 11.8 years, M:F = 14:9) had IM nailing with a self-locking screw system and PC for the treatment of humeral head and neck metastases. Usually, three proximal locking screws were inserted after IM nailing, and 20.9 ± 8.0 ml of polymethylmethacrylate (PMMA) bone cement was injected in the perimetal osteolytic area.

RESULTS

Regional anesthesia with interscalene block was performed in 87.0% (20/23), and the duration of surgery (from anesthesia to awakening) was approximately 40-55 min. Red blood cell was not transfused intra- and/or postoperatively in 65.2% (15/23). The localized preoperative pain (visual analog scale (VAS), 8.2 ± 3.1) was gradually decreased at postoperative 1 week (VAS, 4.9 ± 2.1) and at 6 weeks (VAS, 2.9 ± 2.1) (P < 0.001). Among nine patients who underwent F-18-FDG PET/CT, the proximal humeral metastasis around PC showed improved, stable, and aggravated states in five (55.6%), three (33.3%), and one patient (11.1%), respectively. Meanwhile, 88.8% (8/9) of patients showed aggravation at the naive bone metastasis area.

CONCLUSION

The selection of the self-locking screw type of the IM nail and PC was helpful in preventing fixation failure for joint-preserving palliative surgery in the proximal humeral metastasis.

Inhibition of Histone Deacetylases Attenuates Morphine Tolerance and Restores MOR Expression in the DRG of BCP Rats

The easily developed morphine tolerance in bone cancer pain (BCP) significantly hindered its clinical use. Increasing evidence suggests that histone deacetylases (HDACs) regulate analgesic tolerance subsequent to continuous opioid exposure. However, whether HDACs contribute to morphine tolerance in the pathogenesis of BCP is still unknown. In the current study, we explored the possible engagement of HDACs in morphine tolerance during the pathogenesis of BCP. After intra-tibia tumor cell inoculation (TCI), we found that the increased expression of HDACs was negatively correlated with the decreased expression of MOR in the DRG following TCI. The paw withdrawal threshold (PWT) and percentage maximum possible effects (MPEs) decreased rapidly in TCI rats when morphine was used alone. In contrast, the concomitant use of SAHA and morphine significantly elevated the PWT and MPEs of TCI rats compared to morphine alone. Additionally, we found that SAHA administration significantly elevated MOR expression in the DRG of TCI rats with or without morphine treatment. Moreover, the TCI-induced increase in the co-expression of MOR and HDAC1 in neurons was significantly decreased after SAHA administration. These results suggest that HDACs are correlated with the downregulation of MOR in the DRG during the pathogenesis of BCP. Inhibition of HDACs using SAHA can be used to attenuate morphine tolerance in BCP.

Suppression of HDAC2 in Spinal Cord Alleviates Mechanical Hyperalgesia and Restores KCC2 Expression in a Rat Model of Bone Cancer Pain

Epigenetic modulation participates in the mechanism of multiple types of pathological pain, so targeting the involved regulators may be a promising strategy for pain treatment. Our previous research identified the analgesic effect of the histone deacetylase (HDAC) inhibitor trichostatin A (TSA) on mechanical hyperalgesia in a rat model of bone cancer pain (BCP) via restoration of μ-opioid receptor (MOR) expression. However, the specific types of HDACs contributing to BCP have not been explored. The present study investigated the expression pattern of some common HDACs and found that HDAC2 was up-regulated in a time-dependent manner in the lumbar spinal cord of BCP rats. TSA application suppressed HDAC2 expression in cultured PC12 cells and reversed the augmented HDAC2 in BCP rats. An RNA-interfering strategy confirmed the essential role of HDAC2 in the modulation of mechanical hyperalgesia following tumor cell inoculation, and we further examined its possible downstream targets. Notably, HDAC2 knock-down did not restore MOR expression, but it robustly reversed the down-regulation of potassium-chloride cotransporter 2 (KCC2). The impaired KCC2 expression is a vital mechanism of many types of pathological pain. Therefore, our results demonstrated that HDAC2 in spinal cord contributed to the mechanical hyperalgesia in BCP rats, and this effect may be associated with KCC2 modulation.

Mechanisms of, and Adjuvants for, Bone Pain

Metastatic bone pain is a complex, poorly understood process. Understanding the unique mechanisms causing cancer-induced bone pain may lead to potential therapeutic targets. This article discusses the effects of osteoclast overstimulation within the tumor microenvironment; the role of inflammatory factors at the tumor-nociceptor interface; the development of structural instability, causing mechanical nerve damage; and, ultimately, the neuroplastic changes in the setting of sustained pain. Several adjuvant therapies are available to attenuate metastatic bone pain. This article discusses the role of pharmacologic therapies, surgery, kyphoplasty, vertebroplasty, and radiofrequency ablation.

Electrical peripheral nerve stimulation relieves bone cancer pain by inducing Arc protein expression in the spinal cord dorsal horn

Objective

The analgesic effect on chronic pain of peripheral nerve stimulation (PNS) has been proven, but its underlying mechanism remains unknown. Therefore, this study aimed to assess the analgesic effect of PNS on bone cancer pain in a rat model and to explore the underlying mechanism.

Materials and methods

PNS on sciatic nerves with bipolar electrode was performed in both naïve and bone cancer pain model rats. Then, the protein levels of activity-regulated cytoskeleton-associated protein (Arc), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid–type glutamate receptor 1 (GluA1), and phosphate N-methyl-d-aspartic acid-type glutamate receptor subunit 2B (pGluNR2B) in spinal cord were evaluated by immunohistochemistry and Western blotting. Thermal paw withdraw latency and mechanical paw withdraw threshold were used to estimate the analgesic effect of PNS on bone cancer pain. Intrathecal administration of Arc shRNA was used to inhibit Arc expression in the spinal cord.

Results

PNS at 60 and 120 Hz for 20 min overtly induced Arc expression in the spinal cord, increased thermal pain thresholds in naïve rats, and relieved bone cancer pain; meanwhile, 10 Hz PNS did not achieve those results. In addition, PNS at 60 and 120 Hz also reduced the expression of GluA1, but not pGluNR2B, in the spinal cord. Finally, the anti-nociceptive effect and GluA1 downregulation induced by PNS were inhibited by intrathecal administration of Arc shRNA.

Conclusion

PNS (60 Hz, 0.3 mA) can relieve bone-cancer-induced allodynia and hyperalgesia by upregulating Arc protein expression and then by decreasing GluA1 transcription in the spinal cord dorsal horn.

Percutaneous Palliative Surgery for Femoral Neck Metastasis Using Hollow Perforated Screw Fixation and Bone Cement

Background:

We introduced a new surgical method of percutaneous hollow perforated screw (HPS) fixation with concomitant bone-cement injection for the treatment of femoral neck metastasis and evaluated its efficacy for the palliative treatment of patients with advanced cancer.

Methods:

The study included 87 patients (39 men and 48 women; mean age [and standard deviation], 64.2 ± 10.2 years; mean body mass index, 24.3 ± 3.2 kg/m²) who underwent percutaneous HPS fixation and cementoplasty (mean cement amount, 19.8 ± 8.3 mL) for the treatment of unilateral or bilateral femoral neck metastasis (total, 95 sites). Anesthesia type, operative time, operative blood loss, pain score changes (according to a visual analog scale [VAS]), walking status, and complications were assessed. The mean duration of follow-up was 10.1 ± 10.8 months (range, 2 to 43 months).

Results:

The majority of procedures were performed with local (3 patients) or spinal (72 patients) anesthesia (total, 75 patients; 86.2%). The mean operative time was 35.9 minutes, and the mean operative blood loss was 97.0 mL. The VAS score for pain improved significantly, from 6.8 ± 2.8 preoperatively to 2.8 ± 2.3 and 2.9 ± 2.8 at 1 and 6 weeks postoperatively (p < 0.001). At 6 weeks postoperatively, 63 (80.8%) of 78 patients were able to walk (with either normal or limping gait, a cane or crutch, or a walker). The prevalence of major local complications (cement leakage into the hip joint, fixation failure) was 10.5% (10 of 95), but major systemic complications (distant cement embolism) were not found.

Conclusions:

Percutaneous HPS fixation and cementoplasty for the treatment of femoral neck metastasis is a minimally invasive technique that provides effective pain relief and early stabilization. This technique seems to be useful for patients with advanced cancer for whom open surgery would be hazardous.

Level of Evidence:

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The Effect of Gabapentin and Tramadol in Cancer Pain Induced by Glioma Cell in Rat Femur

Preclinical Research The presence of pain as part of the cancer process is variable. Glioblastoma multiform (GBM) can produce bone metastasis, a condition that involves other pathological phenotypes including neuropathic and inflammatory pain. Tramadol and gabapentin are drugs used in the treatment of neuropathic pain. However, there are no studies evaluating their analgesic effects in bone metastasis. We produced a pain model induced by the inoculation of glioma cells (10⁵ ) into the rat femur, by perforating the intercodiloid fossa. Painful behavior was evaluated by measuring mechanical allodynia using the Von Frey test while thermal hyperalgesia was assessed in the plantar test. Histopathological features were evaluated and antinociceptive responses were compared using tramadol and gabapentin. The inoculation of cells inside the right femur produced nociceptive behaviors. Tramadol and gabapentin produced an anti-allodynic effect in this condition, but tramadol did not produce an anti-hyperalgesic response. The development of this model will allow us to perform tests to elucidate the pathology of bone metastasis, cancer pain, and in particular the pain produced by glioma. Drug Dev Res 78 : 173-183, 2017. © 2017 Wiley Periodicals, Inc.

Neuron-restrictive silencer factor-mediated downregulation of μ-opioid receptor contributes to the reduced morphine analgesia in bone cancer pain

Neuron-restrictive silencer factor–induced downregulation of μ-opioid receptor is involved in the reduction of morphine analgesia in sarcoma-induced bone cancer pain.

Bone cancer pain has been reported to have unique mechanisms and is resistant to morphine treatment. Recent studies have indicated that neuron-restrictive silencer factor (NRSF) plays a crucial role in modulating the expression of the μ-opioid receptor (MOR) gene. The present study elucidates the regulatory mechanisms of MOR and its ability to affect bone cancer pain. Using a sarcoma-inoculated murine model, pain behaviors that represent continuous or breakthrough pain were evaluated. Expression of NRSF in the dorsal root ganglion (DRG) and spinal dorsal horn was quantified at the transcriptional and translational levels, respectively. Additionally, chromatin immunoprecipitation assays were used to detect NRSF binding to the promoter of MOR. Furthermore, NRSF was genetically knocked out by antisense oligodeoxynucleotide, and the expression of MOR and the effect of morphine were subsequently analyzed. Our results indicated that in a sarcoma murine model, NRSF expression is upregulated in dorsal root ganglion neurons, and the expression of NRSF mRNA is significantly negatively correlated with MOR mRNA expression. Additionally, chromatin immunoprecipitation analysis revealed that NRSF binding to the neuron-restrictive silencer element within the promoter area of the MOR gene is promoted with a hypoacetylation state of histone H3 and H4. Furthermore, genetically knocking down NRSF with antisense oligodeoxynucleotide rescued the expression of MOR and potentiated the systemic morphine analgesia. The present results suggest that in sarcoma-induced bone cancer pain, NRSF-induced downregulation of MOR is involved in the reduction of morphine analgesia. Epigenetically, up-regulation of MOR could substantially improve the effect of system delivery of morphine.

Effect of systemic injection of heterogenous and homogenous opioids on peripheral cellular immune response in rats with bone cancer pain: A comparative study

Exogenous and endogenous opioids have been shown to modulate the immune system. Morphine-induced immunosuppression has been investigated extensively. However, the immune-regulating function of endogenous opioid peptides is unclear. The present study aimed to evaluate the difference in effects on cellular immune function between recombinant rat β-endorphin (β-EP; 50 µg/kg) and plant source morphine (10 mg/kg) via intraperitoneal injection treatment in a rat model of bone cancer pain. Walker 256 cells were injected into a tibial cavity injection to establish the bone cancer pain model. The paw withdrawal thresholds and body weights were measured prior to surgery, at 6 days after surgery, and following 1, 3,6 and 8 treatments. The spleen cells were harvested for detection of T cell proliferation, natural killer (NK) cell cytotoxicity, and the relative quantities of T cell subtypes (CD3⁺, CD4⁺ and CD8⁺ cells). Plasma levels of interleukin-2 (IL-2) were also determined. It was found that single or multiple treatments with β-EP (a homogenous opioid peptide) and morphine (a heterogenous opioid) had good analgesic effects on bone cancer pain, while the analgesia provided by morphine was stronger than that of β-EP. Treatment with β-EP 3, 6 and 8 times increased the body weight gain in the rat model of bone cancer pain, while morphine treatment had on effect on it. With regard to immunomodulatory functions, β-EP treatment increased T cell proliferation and NK cell cytotoxicity, and increased the relative quantities of T cell subtypes, but no effect on T cell secretion. However, morphine treatment decreased T cell proliferation and the levels of T cell subtypes. These data indicate that opioids from different sources have different effects on cellular immune function in vivo. A small dose of homogenous opioid peptide exhibited positive effects (analgesia and immune enhancement) on cancer pain. These results provide experimental evidence supporting the exploitation of human opioids for the treatment of cancer pain.

Mas-Related Gene (Mrg) C Activation Attenuates Bone Cancer Pain via Modulating Gi and NR2B

Objective

This study is to investigate the role of Mas-related gene (Mrg) C in the pathogenesis and treatment of bone cancer pain (BCP).

Methods

BCP mouse model was established by osteosarcoma cell inoculation. Pain-related behaviors were assessed with the spontaneous lifting behavior test and mechanical allodynia test. Expression levels of MrgC, Gi, and NR2B in the spinal cord were detected with Western blot analysis and immunohistochemistry.

Results

Pain-related behavior tests showed significantly increased spontaneous flinches (NSF) and decreased paw withdrawal mechanical threshold (PWMT) in mouse models of BCP. Western blot analysis showed that, compared with the control group and before modeling, all the expression levels of MrgC, Gi, and NR2B in the spinal cord of BCP mice were dramatically elevated, which were especially increased at day 7 after operation and thereafter, in a time-dependent manner. Moreover, the treatment of MrgC agonist BAM8-22 significantly up-regulated Gi and down-regulated NR2B expression levels, in the spinal cord of BCP mice, in a time-dependent manner. On the other hand, anti-MrgC significantly down-regulated Gi expression, while dramatically up-regulated NR2B expression, in the BCP mice. Similar results were obtained from the immunohistochemical detection. Importantly, BAM8-22 significantly attenuated the nociceptive behaviors in the BCP mice.

Conclusion

Our results indicated the MrgC-mediated Gi and NR2B expression alterations in the BCP mice, which might contribute to the pain hypersensitivity. These findings may provide a novel strategy for the treatment of BCP in clinic.

CREB-regulated transcription coactivator 1 enhances CREB-dependent gene expression in spinal cord to maintain the bone cancer pain in mice

Background

cAMP response element binding protein (CREB)-dependent gene expression plays an important role in central sensitization. CREB-regulated transcription coactivator 1 (CRTC1) dramatically increases CREB-mediated transcriptional activity. Brain-derived neurotrophic factor, N-methyl-d-aspartate receptor subunit 2B, and miRNA-212/132, which are highly CREB responsive, function downstream from CREB/CRTC1 to mediate activity-dependent synaptic plasticity and in turn loops back to amplify CREB/CRTC1 signaling. This study aimed to investigate the role of spinal CRTC1 in the maintenance of bone cancer pain using an RNA interference method.

Results

Osteosarcoma cells were implanted into the intramedullary space of the right femurs of C3H/HeNCrlVr mice to induce bone cancer pain. Western blotting was applied to examine the expression of spinal phospho-Ser133 CREB and CRTC1. We further investigated effects of repeated intrathecal administration with Adenoviruses expressing CRTC1-small interfering RNA (siRNA) on nociceptive behaviors and on the upregulation of CREB/CRTC1-target genes associated with bone cancer pain. Inoculation of osteosarcoma cells induced progressive mechanical allodynia and spontaneous pain, and resulted in upregulation of spinal p-CREB and CRTC1. Repeated intrathecal administration with Adenoviruses expressing CRTC1-siRNA attenuated bone cancer–evoked pain behaviors, and reduced CREB/CRTC1-target genes expression in spinal cord, including BDNF, NR2B, and miR-212/132.

Conclusions

Upregulation of CRTC1 enhancing CREB-dependent gene transcription in spinal cord may play an important role in bone cancer pain. Inhibition of spinal CRTC1 expression reduced bone cancer pain. Interruption to the positive feedback circuit between CREB/CRTC1 and its targets may contribute to the analgesic effects. These findings may provide further insight into the mechanisms and treatment of bone cancer pain.

Pulsed Radiofrequency Application for the Treatment of Pain Secondary to Sacroiliac Joint Metastases

Sacroiliac (SI) joint pain can result from degeneration, infection, malignancy, and trauma. Patients with metastatic bone pain who do not respond to conventional treatment may need more aggressive neuroinvasive approaches. Recently, pulsed radiofrequency (PRF) neuromodulation has emerged as a promising treatment alternative for refractory cases of SI joint pain. Nevertheless, there is no report on the treatment of pain arising from SI joint metastases with PRF. We are reporting about a 63-year-old woman suffering from buttock pain due to breast cancer metastases in the SI joint. We treated this patient with PRF neuromodulation of the L4-S3 primary dorsal rami and lateral branches using a rotating curved needle technique. The patient tolerated the procedures well, without any complications. She experienced about 70% reduction in pain, and pain relief was sustained for 10 months. This result suggests that PRF neuromodulation is a safe, effective treatment for pain from SI joint metastases.

Spine Cryoablation: Pain Palliation and Local Tumor Control for Vertebral Metastases

BACKGROUND AND PURPOSE

Percutaneous cryoablation has emerged as a minimally invasive technique for the management of osseous metastases. The purpose of this study was to assess the safety and effectiveness of percutaneous imaging-guided spine cryoablation for pain palliation and local tumor control for vertebral metastases.

MATERIALS AND METHODS

Imaging-guided spine cryoablation was performed in 14 patients (31 tumors) with vertebral metastases refractory to conventional chemoradiation therapy or analgesics, to achieve pain palliation and local tumor control in this retrospective study. Spinal nerve and soft-tissue thermal protection techniques were implemented in all ablations. Patient response was evaluated by a pain numeric rating scale administered before the procedure and 1 week, 1 month, and 3 months after the procedure. Pre- and postprocedural analgesic requirements (expressed as morphine-equivalent dosages) were also analyzed at the same time points. Pre- and postprocedural cross-sectional imaging was evaluated in all patients to assess local control (no radiographic evidence of disease at the treated sites). Complications were monitored. Analysis of the primary end points was undertaken via paired-comparison procedures by using the Wilcoxon signed rank test.

RESULTS

Thirty-one tumors were ablated in 14 patients (9 women and 5 men; 20-73 years of age; mean age, 53 years). The most common tumor location was in the lumbar spine (n = 14, 45%), followed by the thoracic spine (n = 8, 26%), sacrum (n = 6, 19%), coccyx (n = 2, 6%), and cervical spine (n = 1, 3%). There were statistically significant decreases in the median numeric rating scale score and analgesic usage at 1-week, 1-month, and 3-month time points (P < .001 for all). Local tumor control was achieved in 96.7% (30/31) of tumors (median follow-up, 10 months). Two patients had transient postprocedural unilateral lower extremity radiculopathy and weakness.

CONCLUSIONS

Percutaneous imaging-guided spine cryoablation is a safe and effective treatment for pain palliation and local tumor control for vertebral metastases.

Behavioral and neurochemical analysis of ongoing bone cancer pain in rats

Cancer-induced bone pain is described as dull, aching ongoing pain. Ongoing bone cancer pain was characterized after intratibial injection of breast cancer cells in rats. Cancer produced time-dependent bone remodeling and tactile hypersensitivity but no spontaneous flinching. Conditioned place preference (CPP) and enhanced dopamine (DA) release in the nucleus accumbens (NAc) shell was observed after peripheral nerve block (PNB) selectively in tumor-bearing rats revealing nociceptive-driven ongoing pain. Oral diclofenac reversed tumor-induced tactile hypersensitivity but did not block PNB-induced CPP or NAc DA release. Tumor-induced tactile hypersensitivity, and PNB-induced CPP and NAc DA release, was blocked by prior subcutaneous implantation of a morphine pellet. In sham rats, morphine produced a modest but sustained increase in NAc DA release. In contrast, morphine produced a transient 5-fold higher NAc DA release in tumor bearing rats compared with sham morphine rats. The possibility that this increased NAc DA release reflected the reward of pain relief was tested by irreversible blockade of rostral anterior cingulate cortex (rACC) μ-opioid receptors (MORs). The rACC MOR blockade prevented the morphine-induced transient increased NAc DA release in tumor bearing rats but did not affect morphine-induced effects in sham-operated animals. Consistent with clinical experience, ongoing cancer pain was controlled by morphine but not by a dose of diclofenac that reversed evoked hypersensitivity. Additionally, the intrinsic reward of morphine can be dissociated from the reward of relief of cancer pain by blockade of rACC MOR. This approach allows mechanistic and therapeutic assessment of ongoing cancer pain with likely translation relevance.

Bone cancer pain: from mechanism to therapy

PURPOSE OF REVIEW

To review how common cancers such as breast, lung, and prostate cancers drive significant and frequently life-altering pain when the cells metastasize to bones.

RECENT FINDINGS

Similar to cancer, the factors that drive bone cancer pain evolve and change with disease progression. Bone cancer pain has both a nociceptive and neuropathic component. The nociceptive component is driven by the release of algogenic substances by tumor and their associated stromal cells, acidosis caused by bone-destroying osteoclasts, and mechanical destabilization and fracture of the bone. The neuropathic component is induced by tumor cell growth which injures and destroys the distal ends of nerve fibers that normally innervate the bone, as well as by inducing a highly pathological sprouting of both sensory and sympathetic nerve fibers.

SUMMARY

There is both a nociceptive and neuropathic component of bone cancer pain. In bone cancer pain, there is frequently a continual afferent drive of sensory nerve fibers that induces a peripheral and central sensitization. These mechanistic insights have begun to lead to advances in not only how we understand bone cancer pain but to the development of new therapies to treat bone cancer pain.

Ablation of musculoskeletal metastases: pain palliation, fracture risk reduction, and oligometastatic disease

Thermal ablation is an effective, minimally invasive alternative to conventional therapies in the palliation of painful musculoskeletal metastases and an emerging approach to obtain local tumor control in the setting of limited metastatic disease. Various thermal ablation technologies have been applied to bone and soft tissue tumors and may be used in combination with percutaneous cement instillation for skeletal lesions with or at risk for pathologic fracture. This article reviews current practices of percutaneous ablation of musculoskeletal metastases with an emphasis on radiofrequency ablation and cryoablation of painful skeletal metastases.

[Management of symptomatic bone metastases in urologic malignancies]

Bone metastases and related skeletal events are frequent complications of genitourinary malignancies. Hypercalcemia, chronic pain, pathologic bone fractures, transverse spinal cord syndromes, and myelosuppression are possible clinical signs. Treatment is usually multimodal and multidisciplinary, and covers oncologic and medical therapy, pain therapy as well as radiation therapy. In case of pathologic bone fractures or instabilities surgery might be indicated.