Systemic metabolic radiopharmaceutical therapy in the treatment of metastatic bone pain

Comparison of the clinical outcomes of intramedullary nailing between impending and completed pathological fractures caused by metastatic femoral tumors from solid cancers

BACKGROUND

We examined the treatment outcomes following intramedullary nailing in patients with metastatic femoral tumors, excluding those from hematological malignancies.

METHODS

We retrospectively evaluated treatment outcomes following intramedullary nailing between patients who underwent preventative surgery compared with those who had surgery following pathological fracture. Patients who underwent preventative surgery (Mirels' score ≥8) were allocated to the impending fracture group (n = 11) and those who underwent surgery after pathological fracture were allocated to the completed fracture group (n = 20).

RESULTS

Duration of surgery was significantly shorter in the impending fracture group than in the completed fracture group. Median blood loss was significantly less, and the median duration of hospital stay was significantly shorter in the impending fracture group than in the completed fracture group. Among patients who died following surgery, the median postoperative survival duration was significantly longer in the impending fracture group than in the completed fracture group. Significantly more patients regained walking function in the impending fracture group than in the completed fracture group. Regarding complications, infection occurred in one patient in the completed fracture group. No implant damage was observed in either group.

CONCLUSIONS

Patients with metastatic femoral tumors who underwent intramedullary nailing in the impending fracture group had better postoperative survival and gait function, less blood loss, and shorter durations of surgery and hospital stay than those in the completed fracture group. These findings indicate the importance of early diagnosis and treatment and value of treatment prior to fracture occurrence.

Nano-radiopharmaceuticals as therapeutic agents

In recent years, there has been an increased interest in exploring the potential synergy between nanotechnology and nuclear medicine. The application of radioactive isotopes, commonly referred to as radiopharmaceuticals, is recognized in nuclear medicine for diagnosing and treating various diseases. Unlike conventional pharmaceutical agents, radiopharmaceuticals are designed to work without any pharmacological impact on the body. Nevertheless, the radiation dosage employed in radiopharmaceuticals is often sufficiently high to elicit adverse effects associated with radiation exposure. Exploiting their capacity for selective accumulation on specific organ targets, radiopharmaceuticals have utility in treating diverse disorders. The incorporation of nanosystems may additionally augment the targeting capability of radiopharmaceuticals, leveraging their distinct pharmacokinetic characteristics. Conversely, radionuclides could be used in research to assess nanosystems pharmacologically. However, more investigation is needed to verify the safety and effectiveness of radiopharmaceutical applications mediated by nanosystems. The use of nano-radiopharmaceuticals as therapeutic agents to treat various illnesses and disorders is majorly covered in this review. The targeted approach to cancer therapy and various types of nanotools for nano-radiopharmaceutical delivery, is also covered in this article.

Cancer Treatment Related Pain

When discussing cancer treatment, it is important to be aware of the potential toxicities and side effects associated with these treatments.

Efficacy and safety of 177Lu-DOTMP in palliative treatment of symptomatic skeletal metastases: a prospective study

AIMS

Bone-seeking radiopharmaceutical 177Lu-DOTMP with favorable pharmacokinetics in the preclinical studies has been evaluated for its role in reducing bone pain and improving quality of life (QOL) in patients with symptomatic skeletal metastases.

METHOD

Patients with painful widespread skeletal metastases documented on 99mTc-MDP bone scintigraphy were intravenously administered 37 MBq/kg of 177Lu-DOTMP. Visual analogue score (VAS), analgesic score, European Cooperative Group of Oncology (ECOG) and the European Organization of Research and Treatment of Cancer QLQ-C30 of all the patients were assessed at baseline and posttherapy follow-up. Adverse effects were graded according to NCI-CTCAE V 5.0.

RESULTS

Twenty-seven patients with painful widespread skeletal metastases (men 18; median age 61 years; range: 18-81) were studied for their responses as complete response, partial response, minimal response, no response and pain progression based on VAS and analgesic score. Overall response was seen in 77.8% of patients (complete, partial and minimal in 29.6, 33.3 and 14.8%, respectively) with significant improvement in median VAS and mean analgesic score at 2 months posttherapy from baseline (P < 0.001). The best response was seen in patients with breast cancer (100%) followed by prostate cancer (81%) and lung cancer (28%). Improvement in QOL was noted in 40% of patients, with change in ECOG score from 3.07 ± 0.67 at baseline to 2.6 ± 0.9 at 2 months posttherapy. Grade 2/3 anemia, grade 1/2 leukopenia and grade 1/3 thrombocytopenia were seen in 37, 11.1 and 18.5% patients respectively in the follow-up.

CONCLUSION

177Lu-DOTMP appears to be efficacious treatment for bone pain palliation with improvement in QOL though less effective in patients with lung cancer. The patients had transient mild-moderate hematotoxicity.

The radio-europium impurities in [153Sm]-EDTMP production: a review of isolation methods

Many human cancers predominantly metastasize to the bone which causes bone pain and other symptoms. However, the management of bone metastases is challenging. Radionuclide therapy using low-energy beta-emitting radionuclides has yielded encouraging results. The aim of this therapy is to deliver the maximum dose to the metastatic sites but a minimal dose to the normal tissue. Samarium-153 [153Sm]Sm-Ethylenediamine tetramethylene phosphonate (EDTMP) is an FDA and European Medicine Agency approved (Quadramet) radionuclide and is widely used for bone pain palliation. 153Sm is reactor produced, and the presence of europium impurities is thus unavoidable. This in turn causes an increase in the hospital radioactive waste burden and in radiation absorbed doses to the patients, and therefore it is a concern. The effective removal of these impurities is thus highly desirable before its administration to the patients. In this article, we present a detailed review of the various methods described in the literature for separation of 153Sm and Eu, that is solvent extraction, ion-exchange chromatography, electrochromatography, electrochemical separation and supported ionic liquid phase.

Radioactive polymeric nanoparticles for biomedical application

Nowadays, emerging radiolabeled nanosystems are revolutionizing medicine in terms of diagnostics, treatment, and theranostics. These radionuclides include polymeric nanoparticles (NPs), liposomal carriers, dendrimers, magnetic iron oxide NPs, silica NPs, carbon nanotubes, and inorganic metal-based nanoformulations. Between these nano-platforms, polymeric NPs have gained attention in the biomedical field due to their excellent properties, such as their surface to mass ratio, quantum properties, biodegradability, low toxicity, and ability to absorb and carry other molecules. In addition, NPs are capable of carrying high payloads of radionuclides which can be used for diagnostic, treatment, and theranostics depending on the radioactive material linked. The radiolabeling process of nanoparticles can be performed by direct or indirect labeling process. In both cases, the most appropriate must be selected in order to keep the targeting properties as preserved as possible. In addition, radionuclide therapy has the advantage of delivering a highly concentrated absorbed dose to the targeted tissue while sparing the surrounding healthy tissues. Said another way, radioactive polymeric NPs represent a promising prospect in the treatment and diagnostics of cardiovascular diseases such as cardiac ischemia, infectious diseases such as tuberculosis, and other type of cancer cells or tumors.

Progress in Targeted Alpha-Particle-Emitting Radiopharmaceuticals as Treatments for Prostate Cancer Patients with Bone Metastases

Bone metastasis remains a major cause of death in cancer patients, and current therapies for bone metastatic disease are mainly palliative. Bone metastases arise after cancer cells have colonized the bone and co-opted the normal bone remodeling process. In addition to bone-targeted therapies (e.g., bisphosphonate and denosumab), hormone therapy, chemotherapy, external beam radiation therapy, and surgical intervention, attempts have been made to use systemic radiotherapy as a means of delivering cytocidal radiation to every bone metastatic lesion. Initially, several bone-seeking beta-minus-particle-emitting radiopharmaceuticals were incorporated into the treatment for bone metastases, but they failed to extend the overall survival in patients. However, recent clinical trials indicate that radium-223 dichloride (223RaCl2), an alpha-particle-emitting radiopharmaceutical, improves the overall survival of prostate cancer patients with bone metastases. This success has renewed interest in targeted alpha-particle therapy development for visceral and bone metastasis. This review will discuss (i) the biology of bone metastasis, especially focusing on the vicious cycle of bone metastasis, (ii) how bone remodeling has been exploited to administer systemic radiotherapies, and (iii) targeted radiotherapy development and progress in the development of targeted alpha-particle therapy for the treatment of prostate cancer bone metastasis.

Bone Health and Bone-Targeted Therapies for Prostate Cancer: ASCO Endorsement of a Cancer Care Ontario Guideline

PURPOSE

In 2017, Cancer Care Ontario's Program in Evidence-Based Care released the Bone Health and Bone-Targeted Therapies for Prostate Cancer guideline. This guideline included recommendations across a relatively broad clinical spectrum within prostate cancer. Topics addressed ranged from management of osteoporotic fracture risk in nonmetastatic disease to management of men with castration-resistant prostate cancer metastatic to bone. ASCO has a policy and set of procedures for endorsing clinical practice guidelines that have been developed by other professional organizations.

METHODS

The Bone Health and Bone-Targeted Therapies for Prostate Cancer guideline was reviewed for developmental rigor by methodologists. An ASCO Expert Panel then reviewed the content and the recommendations.

RESULTS

The ASCO Expert Panel determined that the recommendations from the Bone Health and Bone-Targeted Therapies for Prostate Cancer guideline were clear, thorough, and based on the most relevant scientific evidence. ASCO wholly endorses the Bone Health and Bone-Targeted Therapies for Prostate Cancer guideline.

RECOMMENDATIONS

The ASCO Expert Panel endorses all the original guideline recommendations as written and offers a series of discussion points to guide practice for clinicians as they manage bone-related risks within this patient population.

Systemic Treatment of Bone Disease in Metastatic Urinary Malignancies

CONTEXT

Bone metastasis is a common site of metastatic disease in patients with genitourinary malignancies. Given that the presence of bone metastasis decreases survival and has a negative impact on quality of life impact, it is critical to optimize management of this patient population.

OBJECTIVE

To systematically review literature on the systemic treatment of bone metastasis in prostate cancer, renal cell carcinoma, urothelial carcinoma, and germ cell tumors.

EVIDENCE ACQUISITION

We performed a nonsystematic critical review of PubMed/Medline, clinicaltrials.gov, and the Cochrane Library from January 2001 to February 2019. Identified reports were reviewed according to the Consolidated Standards of Reporting Trials, and selected based on reporting skeletal related events and symptomatic skeletal events for patients with urologic malignancies.

EVIDENCE SYNTHESIS

Skeletal metastases occur frequently in genitourinary malignancies, at rates around 80% for patients with metastatic prostate cancer and 30% for patients with metastatic renal cell and urothelial carcinoma, and are uncommon in patients with germ cell tumors. Skeletal related events and symptomatic skeletal events can occur in these patients. Optimization of bone health involves dietary and lifestyle modifications, and use of osteoclast-targeted agents in select individuals. Additionally, disease-modifying agents, such as radiopharmaceutical, immunotherapy, and cMET inhibitors, which have activity in the bone, have improved outcomes for patients, including skeletal-related events and symptomatic skeletal events.

CONCLUSIONS

While the presence of bone metastases is associated with increased mortality and worse outcomes in patients with genitourinary malignancies, strategies have been developed to improve quality of life and survival for patients with skeletal metastases. Future studies investigating novel therapeutic options and bone supporting agents are warranted to target this patient population.

PATIENT SUMMARY

In this report, we reviewed the current literature and recent clinical trials involving treatment of bone metastases in urinary cancers. The use of bone-targeting agents can improve outcomes for patients, and additional lifestyle modification can optimize bone health in this population.

Bone Pain in Cancer Patients: Mechanisms and Current Treatment

The skeletal system is the third most common site for cancer metastases, surpassed only by the lungs and liver. Many tumors, especially those of the breast, prostate, lungs, and kidneys, have a strong predilection to metastasize to bone, which causes pain, hypercalcemia, pathological skeletal fractures, compression of the spinal cord or other nervous structures, decreased mobility, and increased mortality. Metastatic cancer-induced bone pain (CIBP) is a type of chronic pain with unique and complex pathophysiology characterized by nociceptive and neuropathic components. Its treatment should be multimodal (pharmacological and non-pharmacological), including causal anticancer and symptomatic analgesic treatment to improve quality of life (QoL). The aim of this paper is to discuss the mechanisms involved in the occurrence and persistence of cancer-associated bone pain and to review the treatment methods recommended by experts in clinical practice. The final part of the paper reviews experimental therapeutic methods that are currently being studied and that may improve the efficacy of bone pain treatment in cancer patients in the future.

Personalized Radiation Therapy in Cancer Pain Management

The majority of advanced cancer patients suffer from pain, which severely deteriorates their quality of life. Apart from analgesics, bisphosphonates, and invasive methods of analgesic treatment (e.g., intraspinal and epidural analgesics or neurolytic blockades), radiation therapy plays an important role in pain alleviation. It is delivered to a growing primary tumour, lymph nodes, or distant metastatic sites, producing pain of various intensity. Currently, different regiments of radiation therapy methods and techniques and various radiation dose fractionations are incorporated into the clinical practice. These include palliative radiation therapy, conventional external beam radiation therapy, as well as modern techniques of intensity modulated radiation therapy, volumetrically modulated arch therapy, stereotactic radiosurgery or stereotactic body radiation therapy, and brachytherapy or radionuclide treatment (e.g., radium-223, strontium-89 for multiple painful osseous metastases). The review describes the possibilities and effectiveness of individual patient-tailored conventional and innovative radiation therapy approaches aiming at pain relief in cancer patients.

Targeted Radionuclide Therapy of Painful Bone Metastases: Past Developments, Current Status, Recent Advances and Future Directions

Bone pain arising from secondary skeletal malignancy constitutes one of the most common types of chronic pain among patients with cancer which can lead to rapid deterioration of the quality of life. Radionuclide therapy using bone-seeking radiopharmaceuticals based on the concept of localization of the agent at bone metastases sites to deliver focal cytotoxic levels of radiation emerged as an effective treatment modality for the palliation of symptomatic bone metastases. Bone-seeking radiopharmaceuticals not only provide palliative benefit but also improve clinical outcomes in terms of overall and progression-free survival. There is a steadily expanding list of therapeutic radionuclides which are used or can potentially be used in either ionic form or in combination with carrier molecules for the management of bone metastases. This article offers a narrative review of the armamentarium of bone-targeting radiopharmaceuticals based on currently approved investigational and potentially useful radionuclides and examines their efficacy for the treatment of painful skeletal metastases. In addition, the article also highlights the processes, opportunities, and challenges involved in the development of bone-seeking radiopharmaceuticals. Radium-223 is the first agent in this class to show an overall survival advantage in Castration-Resistant Prostate Cancer (CRPC) patients with bone metastases. This review summarizes recent advances, current clinical practice using radiopharmaceuticals for bone pain palliation, and the expected future prospects in this field.

Ce-141-labeled DOTMP: A theranostic option in management of pain due to skeletal metastases

Owing to its favorable radioactive decay characteristics (T_1/2  = 32.51 d, E_β [max] = 434.6 keV [70.5%] and 580.0 keV [29.5%], E_γ  = 145.4 keV [48.5%]), ¹⁴¹ Ce could be envisaged as a theranostic radionuclide for use in nuclear medicine. The present article reports synthesis and evaluation of ¹⁴¹ Ce complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylenephosphonic acid (DOTMP) as a potent theranostic agent targeting metastatic skeletal lesions. Ce-141 was produced with 314 ± 29 MBq/mg (n = 6) specific activity and >99.9% radionuclidic purity (n = 6). Around 185 MBq dose of [¹⁴¹ Ce]Ce-DOTMP was synthesized with 98.6 ± 0.5% (n = 4) radiochemical yield under optimized conditions of reaction, and the preparation showed adequately high in vitro stability. Biodistribution studies in normal Wistar rats demonstrated significant skeletal localization and retention of injected activity (2.73 ± 0.28% and 2.63 ± 0.22% of injected activity per gram in femur at 3 hours and 14 days post-injection, respectively) with rapid clearance from non-target organs. The results of biodistribution studies were corroborated by serial scintigraphic imaging studies. These results demonstrate the potential utility of ¹⁴¹ Ce-DOTMP as a theranostic molecule for personalized patient care of cancer patients suffering from painful metastatic skeletal lesions.

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.

Anabolic and antiresorptive actions of locally delivered bisphosphonates for bone repair: A review

During the last decades, several research groups have used bisphosphonates for local application to counteract secondary bone resorption after bone grafting, to improve implant fixation or to control bone resorption caused by bone morphogenetic proteins (BMPs). We focused on zoledronate (a bisphosphonate) due to its greater antiresorptive potential over other bisphosphonates. Recently, it has become obvious that the carrier is of importance to modulate the concentration and elution profile of the zoledronic acid locally. Incorporating one fifth of the recommended systemic dose of zoledronate with different apatite matrices and types of bone defects has been shown to enhance bone regeneration significantly in vivo. We expect the local delivery of zoledronate to overcome the limitations and side effects associated with systemic usage; however, we need to know more about the bioavailability and the biological effects. The local use of BMP-2 and zoledronate as a combination has a proven additional effect on bone regeneration. This review focuses primarily on the local use of zoledronate alone, or in combination with bone anabolic factors, in various preclinical models mimicking different orthopaedic conditions.

Cite this article: I. Qayoom, D. B. Raina, A. Širka, Š. Tarasevičius, M. Tägil, A. Kumar, L. Lidgren. Anabolic and antiresorptive actions of locally delivered bisphosphonates for bone repair: A review. Bone Joint Res 2018;7:548–560. DOI: 10.1302/2046-3758.710.BJR-2018-0015.R2.

Inhibitory effects of low intensity pulsed ultrasound on osteoclastogenesis induced in vitro by breast cancer cells

Background

Bone tissue is one of the main sites for breast metastasis; patients diagnosed with advanced breast cancer mostly develop bone metastasis characterized by severe osteolytic lesions, which heavily influence their life quality. Low Intensity Pulsed Ultrasound (LIPUS) is a form of mechanical energy able to modulate various molecular pathways both in cancer and in health cells.

The purpose of the present study was to evaluate for the first time, the ability of LIPUS to modulate osteolytic capability of breast cancer cells.

Methods

Two different approaches were employed: a) Indirect method -conditioned medium obtained by MDA-MB-231 cell line treated or untreated with LIPUS was used to induce osteoclast differentiation of murine macrophage Raw264.7 cell line; and b) Direct method -MDA-MB-231 were co-cultured with Raw264.7 cells and treated or untreated with LIPUS.

Results

LIPUS treatment impaired MDA-MB-231 cell dependentosteoclast differentiation and produced a reduction of osteoclast markers such as Cathepsin K, Matrix Metalloproteinase 9 and Tartrate Resistant Acid Phosphatase, suggesting its role as an effective and safe adjuvant in bone metastasis management.

Conclusion

LIPUS treatment could be a good and safety therapeutic adjuvant in osteolyitic bone metastasis not only for the induction properties of bone regeneration, but also for the reduction of osteolysis.

188Re-HEDP therapy in the therapy of painful bone metastases

For bone-targeted radionuclide therapy (BTRT), different commercial radiopharmaceuticals are available such as strontium-89, 186Rhenium-hydroxyethylidene diphosphonate (186Re-HEDP), Samarium-153-ethylenediamine tetramethylene phosphonic acid, and radium-223. Unfortunately, the commercial available radiopharmaceuticals are very expensive (from 1,200 to 36,000€ per patient in Europe). The 188W/188Re generator is an ideal source for the long-term (4-6 months) continuous availability of 188Re suitable for the preparation of radiopharmaceuticals for different radionuclide therapies. Labeling at HEDP, it can use cost-effective for BTRT, if enough patients are available for therapy. And so, 188Re-HEDP is the ideal candidate in developing countries which high population to replace the other agents. Two German groups documented a response rate of 80% without any severe side effects and similar bone marrow toxicity compared to the other compounds for 188Re-HEDP. Using 188Re-HEDP in repeated treatments, a prolonged overall survival of repeated to single application was observed (from 4.5 months for single to 15.7 months using ≥≥3 applications).

Clinical utility of 188Rhenium-hydroxyethylidene-1,1-diphosphonate as a bone pain palliative in multiple malignancies

¹⁸⁸Rhenium-hydroxyethylidene-1,1-diphosphonate (¹⁸⁸Re-HEDP) is a clinically established radiopharmaceutical for bone pain palliation of patients with metastatic bone cancer. Herein, the effectiveness of ¹⁸⁸Re-HEDP for the palliation of painful bone metastases was investigated in an uncontrolled initial trial in 48 patients with different types of advanced cancers. A group of 48 patients with painful bone metastases of lung, prostate, breast, renal, and bladder cancer was treated with 2.96–4.44 GBq of ¹⁸⁸Re-HEDP. The overall response rate in this group of patients was 89.5%, and their mean visual analog scale score showed a reduction from 9.1 to 5.3 (P < 0.003) after 1 week posttherapy. The patients did not report serious adverse effects either during intravenous administration or within 24 h postadministration of ¹⁸⁸Re-HEDP. Flare reaction was observed in 54.2% of patients between day 1 and day 3. There was no correlation between flare reaction and response to therapy (P < 0.05). Although bone marrow suppression was observed in patients receiving higher doses of ¹⁸⁸Re-HEDP, it did not result in any significant clinical problems. The present study confirmed the clinical utility and cost-effectiveness of ¹⁸⁸Re-HEDP for palliation of painful bone metastases from various types of cancer in developing countries.

Molecular radiotheragnostics in prostate cancer

Two different molecular radio-theragnostic principles are applied in prostate cancer, providing a personalised management for those patients. Firstly, radiopharmaceuticals with the same or similar mechanism of action but different energy (gamma-γ, eg 99mTc-diphosphonates or positron-β+, eg 18F-NaF emitting isotopes) can be used to identify patients with osteoblastic metastases for a treatment with bone seeking beta (β-) or alpha (α-) emitting radionuclides to deliver targeted molecular radiotherapy. A number of such β- emitting molecules have been used for bone palliation. More recently, an alpha emitting 223Ra-dicholoride demonstrated not only symptomatic relief but also significantly improved overall survival in castration-resistant prostate cancer with predominant bone metastases. The second principle involves utilisation of the same prostatic specific membrane antigen (PSMA) or similar compound (eg PSMA-11, PSMA-617), but different label with either β+ (68Ga) or γ (99mTc) emitting radioisotope for imaging and subsequently β- (177Lu) or α (225Ac) emitting radionuclide for treatment.

Efficacy and safety of 153Sm-EDTMP as treatment of painful bone metastasis: a large single-center study

PURPOSE

The purpose of this study is to assess the efficacy of ¹⁵³Sm-EDTMP (Quadramet®) in a clinical setting.

METHODS

We have conducted a retrospective study of all consecutive patients (pts) treated with ¹⁵³Sm-EDTMP for painful bone metastases. At each visit (before and after treatment), four parameters were collected: (i) pain assessment according to the 10-step visual analogue scale (VAS), (ii) sleep disturbance related to pain, (iii) dose of analgesic medication, and (iv) answer to the following closed question "Do you think you obtained a benefit from treatment?" Success of treatment was defined by the combination of these four parameters.

RESULTS

Three hundred seventy consecutive ¹⁵³Sm-EDTMP treatments for painful bone metastases were given. Patients had the following primary tumors: breast carcinoma (153), prostate carcinoma (155), lung carcinoma (27), or other cancers (35). Fifty-eight percent of the patients had received previous external osseous radiotherapy. Ninety-seven percent of the patients were treated with concomitant analgesics and 61% were treated with diphosphonates. A clinical benefit was described in 55.0% of cases at D30. Treatment was more effective in cases of breast and prostate cancers compared with other types of primary cancers. Patients described a benefit at D30 in 62, 58, 6, and 38% of cases of breast, prostate, lung, and other cancers. The subjective efficacy was accompanied by a decrease in analgesic intake in 35.0% of cases.

CONCLUSION

¹⁵³Sm-EDTMP therapy is an effective supportive treatment in patients who suffer from bone metastases, especially in patients with breast or prostate cancer.

Percutaneous Nailing and Cementoplasty for Palliative Management of Supra-Acetabular Iliac Wing Metastases: A Case Report

CASE

A 48-year-old woman was unable to walk due to an extensive osteolytic supra-acetabular iliac wing metastatic lymphoma involving the arcuate line. A minimally invasive technique that combined percutaneous nailing of the iliac bone with a customized nail and cementoplasty (intraosseous injection of polymethylmethacrylate) was performed. At the 1-year follow-up, she was able to walk without crutches, and computed tomography (CT) showed a stable iliac bone fixation.

CONCLUSION

Osteolytic metastasis is a common cause of bone weakening, especially in load-bearing areas. With osteolytic metastases involving the acetabulum, intraosseous injection of bone cement into the weakened acetabulum may reduce pain and prevent fracture. Nailing combined with cementoplasty may be proposed for extensive destruction of the iliac bone involving the arcuate line to relieve pain and allow for resumed walking.

Diagnostic methods for detection of bone metastases

Skeletal metastases are severe complications in the course of cancer, and they indicate a worse prognosis. The use of modern imaging techniques allows rapid diagnosis of bone metastases. Properly selected diagnostic imaging (scintigraphy, positron emission tomography, whole body MRI) allows us to evaluate the number of metastatic foci in the skeletal system. Complementary imaging examinations (X-ray, computed tomography, magnetic resonance imaging) determine the extent of metastasis and its character: osteolytic, osteoblast, mixed). Hypercalcaemia is a symptom of low specificity for metastatic bone disease (a result of osteolysis); nevertheless, it is a significant complication in oncological treatment and worsens the prognosis of the patient. A biopsy is the final stage of the diagnostic process, which allows us to assess cell and tissue changes. Guided biopsies are performed under the control of musculoskeletal imaging methods (CT, MRI) and they are the most promising tools in bone metastases diagnosis. The development of guided biopsy techniques has led to the conclusion that they should be standard in diagnosing bone metastases. Liquid biopsy (LB) seems to be the most promising diagnostic method for detection of bone metastases. LB based on tumour-specific DNA mutation gives an opportunity for early detection and assessment of the molecular heterogeneity of the overall disease.

In Vitro Evaluation of 188Re-HEDP: A Mechanistic View of Bone Pain Palliations

Skeletal metastasis is common in advanced stages of various cancers, particularly of the prostate and breast carcinoma. ¹⁸⁸Re-HEDP (1-hydroxyethane 1, 1-diphosphonic acid) is a clinically established radiopharmaceutical for bone pain palliation of osseous metastasis, and it takes advantage of high bone affinity. The present work aims at elucidating the possible mechanisms of cell killing by ¹⁸⁸Re-HEDP in osteosarcoma cells and biodistribution studies in mice.¹⁸⁸Re-HEDP complex was prepared by using lyophilized HEDP kits prepared in-house. In vitro cellular uptake in mineralized bone matrix was found to be 13.41% ± 0.46% (at 2 hours), which was reduced to 2.44% ± 0.12% in the presence of excess amounts of unlabeled HEDP ligand. Uptake of ¹⁸⁸Re-HEDP in bones of normal Swiss mice in vivo and mineralized bone in vitro indicated its affinity toward the bone matrix. The study also revealed that cellular toxicity and G2/M cell cycle arrest were dose dependent. At higher doses, G2/M cell cycle arrest was observed, which might be the major cause of cell death and a possible mechanism of bone pain relief.

A "mix-and-use" approach for formulation of human clinical doses of 177 Lu-DOTMP at hospital radiopharmacy for management of pain arising from skeletal metastases

Use of bone-seeking radiopharmaceuticals is an established modality in the palliative care of pain due to skeletal metastases. ¹⁷⁷ Lu-DOTMP is a promising radiopharmaceutical for this application owing to the ideally suited decay properties of ¹⁷⁷ Lu and excellent thermodynamic stability and kinetic rigidity of the macrocyclic complex. The aim of the present study is to develop a robust and easily adaptable protocol for formulation of clinical doses of ¹⁷⁷ Lu-DOTMP at hospital radiopharmacy. After extensive radiochemical studies, an optimized strategy for formulation of clinical doses of ¹⁷⁷ Lu-DOTMP was developed, which involves simple mixing of approximately 3.7 GBq of ¹⁷⁷ Lu activity as ¹⁷⁷ LuCl₃ solution to an aqueous solution containing 5 mg of DOTMP and 8 mg of NaHCO₃ . The proposed protocol yielded ¹⁷⁷ Lu-DOTMP with >98% radiochemical purity, and the resultant formulation showed excellent in vitro stability and desired pharmacokinetic properties in animal model. Preliminary clinical investigations in 5 patients showed specific skeletal accumulation with preferential localization in the osteoblastic lesion sites and almost no uptake in soft tissue or any other major nontarget organ. The developed "mix-and-use" strategy would be useful for large number of nuclear medicine centers having access to ¹⁷⁷ Lu activity and would thereby accelerate the clinical translation of ¹⁷⁷ Lu-DOTMP.

PET and PET/CT with radiolabeled choline in prostate cancer: a critical reappraisal of 20 years of clinical studies

We here aim to provide a comprehensive and critical review of the literature concerning the clinical applications of positron emission tomography/computed tomography (PET/CT) with radiolabeled choline in patients with prostate cancer (PCa). We will initially briefly summarize the historical context that brought to the synthesis of [¹¹C]choline, which occurred exactly 20 years ago. We have arbitrarily grouped the clinical studies in three different periods, according to the year in which they were published and according to their relation with their applications in urology, radiotherapy and oncology. Studies at initial staging and, more extensively, studies in patients with biochemical failure, as well as factors predicting positive PET/CT will be reviewed. The capability of PET/CT with radiolabeled choline to provide prognostic information on PCa-specific survival will also be examined. The last sections will be devoted to the use of radiolabeled choline for monitoring the response to androgen deprivation therapy, radiotherapy, and chemotherapy. The accuracy and the limits of the technique will be discussed according to the information available from standard validation processes, including biopsy or histology. The clinical impact of the technique will be discussed on the basis of changes induced in the management of patients and in the evaluation of the response to therapy. Current indications to PET/CT, as officially endorsed by guidelines, or as routinely performed in the clinical practice will be illustrated. Emphasis will be made on methodological factors that might have influenced the results of the studies or their interpretation. Finally, we will briefly highlight the potential role of positron emission tomography/magnetic resonance and of new radiotracers for PCa imaging.

Pharmaceutical and clinical development of phosphonate-based radiopharmaceuticals for the targeted treatment of bone metastases

Therapeutic phosphonate-based radiopharmaceuticals radiolabeled with beta, alpha and conversion electron emitting radioisotopes have been investigated for the targeted treatment of painful bone metastases for >35years. We performed a systematic literature search and focused on the pharmaceutical development, preclinical research and early human studies of these radiopharmaceuticals. The characteristics of an ideal bone-targeting therapeutic radiopharmaceutical are presented and compliance with these criteria by the compounds discussed is verified. The importance of both composition and preparation conditions for the stability and biodistribution of several agents is discussed. Very few studies have described the characterization of these products, although knowledge on the molecular structure is important with respect to in vivo behavior. This review discusses a total of 91 phosphonate-based therapeutic radiopharmaceuticals, of which only six agents have progressed to clinical use. Extensive clinical studies have only been described for (186)Re-HEDP, (188)Re-HEDP and (153)Sm-EDTMP. Of these, (153)Sm-EDTMP represents the only compound with worldwide marketing authorization. (177)Lu-EDTMP has recently received approval for clinical use in India. This review illustrates that a thorough understanding of the radiochemistry of these agents is required to design simple and robust preparation and quality control methods, which are needed to fully exploit the potential benefits of these theranostic radiopharmaceuticals. Extensive biodistribution and dosimetry studies are indispensable to provide the portfolios that are required for assessment before human administration is possible. Use of the existing knowledge collected in this review should guide future research efforts and may lead to the approval of new promising agents.

A DOTA based bisphosphonate with an albumin binding moiety for delayed body clearance for bone targeting

Radiolabeled bisphosphonates are commonly used in the diagnosis and therapy of bone metastases. Blood clearance of bisphosphonates is usually fast and only 30%-50% of the injected activity is retained in the skeleton, while most of the activity is excreted by the urinary tract. A longer blood circulation may enhance accumulation of bisphosphonate compounds in bone metastases. Therefore, a chemically modified macrocyclic bisphosphonate derivative with an additional human albumin binding entity was synthesized and pharmacokinetics of its complex was evaluated. The DOTA-bisphosphonate conjugate BPAMD was compared against the novel DOTAGA-derived albumin-binding bisphosphonate DOTAGA(428-d-Lys)M^BP (L1). The ligands were labeled with ⁶⁸Ga(III) and were evaluated in in vitro binding studies to hydroxyapatite (HA) as well as to human serum albumin. The compounds were finally compared in in vivo PET and ex vivo organ distribution studies in small animals over 6h. Binding studies revealed a consistent affinity of both bisphosphonate tracers to HA. Small animal PET and ex vivo organ distribution studies showed longer blood retention of [⁶⁸Ga]L1. [⁶⁸Ga]BPAMD is initially more efficiently bound to the bone but skeletal accumulation of the modified compound and [⁶⁸Ga]BPAMD equalized at 6h p.i. Ratios of femur epiphyseal plate to ordinary bone showed to be more favorable for [⁶⁸Ga]L1 than for [⁶⁸Ga]BPAMD due to the longer circulation time of the new tracer. Thus, the chemical modification of BPAMD toward an albumin-binding bisphosphonate, L1, resulted in a novel PET tracer which conserves advantages of both functional groups within one and the same molecule. The properties of this new diagnostic tracer are expected to be preserved in ¹⁷⁷Lu therapeutic agent with the same ligand (a theranostic pair).

From palliative therapy to prolongation of survival: (223)RaCl2 in the treatment of bone metastases

Patients with hormone-refractory prostate cancer often have multiple bone metastases. The resulting bone pain is associated with reduced life quality, increased cost of therapy and impairment of overall survival. Trials with bone-targeting β-emitters have mostly showed an effect on alleviation of bone pain along with prolongation in survival, documented in only a limited number of patients. A randomized phase III trial (ALSYMPCA) using the α-emitter (223)RaCl2 (Xofigo®) showed for the first time, a longer overall survival of 3.6 months in treated patients as a sign of an antitumor effect. The time to first skeletal-related events was also significantly longer in the therapy group compared with placebo. Because of the short range of α-emitter, the bone marrow toxicity of radium therapy is low, and so this radionuclide could also be a candidate for combination with chemotherapy. The elimination of (223)RaCl2 is mainly through the gastrointestinal tract and side effects are mainly in this area. The procedure is similar to treatment with other bone-seeking agents and consists of six administrations of 50 kBq/kg bodyweight Xofigo®, repeated every 4 weeks. At present Xofigo® is only approved for hormone-refractory prostate cancer.

Targeted delivery to bone and mineral deposits using bisphosphonate ligands

The high concentration of mineral present in bone and pathological calcifications is unique compared with all other tissues and thus provides opportunity for targeted delivery of pharmaceutical drugs, including radiosensitizers and imaging probes. Targeted delivery enables accumulation of a high local dose of a therapeutic or imaging contrast agent to diseased bone or pathological calcifications. Bisphosphonates (BPs) are the most widely utilized bone-targeting ligand due to exhibiting high binding affinity to hydroxyapatite mineral. BPs can be conjugated to an agent that would otherwise have little or no affinity for the sites of interest. This article summarizes the current state of knowledge and practice for the use of BPs as ligands for targeted delivery to bone and mineral deposits. The clinical history of BPs is briefly summarized to emphasize the success of these molecules as therapeutics for metabolic bone diseases. Mechanisms of binding and the relative binding affinity of various BPs to bone mineral are introduced, including common methods for measuring binding affinity in vitro and in vivo. Current research is highlighted for the use of BP ligands for targeted delivery of BP conjugates in various applications, including (1) therapeutic drug delivery for metabolic bone diseases, bone cancer, other bone diseases, and engineered drug delivery platforms; (2) imaging probes for scintigraphy, fluorescence, positron emission tomography, magnetic resonance imaging, and computed tomography; and (3) radiotherapy. Last, and perhaps most importantly, key structure-function relationships are considered for the design of drugs with BP ligands, including the tether length between the BP and drug, the size of the drug, the number of BP ligands per drug, cleavable tethers between the BP and drug, and conjugation schemes.

Relevance of radiobiological concepts in radionuclide therapy of cancer

PURPOSE

Radionuclide therapy (RNT) is a rapidly growing area of clinical nuclear medicine, wherein radionuclides are employed to deliver cytotoxic dose of radiation to the diseased cells/tissues. During RNT, radionuclides are either directly administered or delivered through biomolecules targeting the diseased site. RNT has been clinically used for diverse range of diseases including cancer, which is the focus of the review.

CONCLUSIONS

The major emphasis in RNT has so far been given towards developing peptides/antibodies and other molecules to conjugate a variety of therapeutic radioisotopes for improved targeting/delivery of radiation dose to the tumor cells. Despite that, many of the RNT approaches have not achieved their desired therapeutic success probably due to poor knowledge about complex and dynamic (i) fate of radiolabeled molecules; (ii) radiation dose delivered; (iii) cellular heterogeneity in tumor mass; and (iv) cellular radiobiological response. Based on understanding gathered during recent years, it may be stated that besides the absorbed dose, the net radiobiological response of tumor/normal cells also determines the clinical response of radiotherapeutic modalities including RNT. The radiosensitivity of tumor/normal cells is governed by radiobiological phenomenon such as radiation-induced bystander effect, genomic instability, adaptive response and low dose hyper-radiosensitivity. These concepts have been well investigated in the context of external beam radiotherapy, but their clinical implications during RNT have received meagre attention. In this direction, a few studies performed using in vitro and in vivo models envisage the possibilities of exploiting the radiobiological knowledge for improved therapeutic outcome of RNT.

Palliative care of bone pain due to skeletal metastases: Exploring newer avenues using neutron activated (45)Ca

INTRODUCTION

With an objective to develop a cost-effective radiochemical formulation for palliation of pain due to skeletal metastases, we have demonstrated a viable method for large-scale production of (45)Ca (t½=163 days, Eβmax=0.3MeV) using moderate flux research reactor, its purification from radionuclidic impurities adopting electrochemical approach and preclinical evaluation of (45)CaCl2.

METHODS

Irradiation parameters were optimized by theoretical calculations for production of (45)Ca with highest possible specific activity along with minimum radionuclidic impurity burden. Based on this, the radioisotope was produced in reactor by irradiation of isotopically enriched (98% in (44)Ca) CaO target at a thermal neutron flux of ~1 × 10(14) n.cm(-2).s(-1) for 4 months. Scandium-46 impurity co-produced along with (45)Ca was efficiently removed adopting an electrochemical separation approach. The bone specificity of (45)CaCl2 was established by in vitro studies involving its uptake in hydroxyapatite (HA) particles and also evaluating its biodistribution pattern over a period of 2 weeks after in vivo administration in Wistar rats.

RESULTS

Thermal neutron irradiation of 100mg of enriched (98% in (44)Ca) CaO target followed by radiochemical processing and electrochemical purification procedure yielded ~37 GBq of (45)Ca with a specific activity of ~370 MBq/mg and radionuclidic purity>99.99%. The reliability and reproducibility of this approach were amply demonstrated by process demonstration in several batches. In vitro studies indicated significant uptake of (45)CaCl2 (up to 65%) in HA particles. In vivo biodistribution studies in Wistar rats showed specific skeletal accumulation (40-46%ID) with good retention over a period of 2 weeks.

CONCLUSIONS

To the best of our knowledge, this is the first study on utilization of (45)CaCl2 in the context of nuclear medicine. The results obtained in this study hold promise and warrant further investigations for future translation of (45)CaCl2 to the clinics, thereby potentially enabling a cost-effective approach for metastatic bone pain palliation especially in developing countries.

Production, biodistribution, and dosimetry of (47)Sc-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid as a bone-seeking radiopharmaceutical

In this study 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid (DOTMP) was used as the polyaminophosphonic acid carrier ligand and the therapeutic potential of the bone seeking radiopharmaceutical (47)Sc-DOTMP was assessed by measuring its dosage-dependent skeletal uptake and then the absorbed radiation dose of human organs was estimated. Because of limited availability of (47)Sc we performed some preliminary studies using (46)Sc. (46)Sc was produced with a specific activity of 116.58 MBq/mg (3.15 mCi/mg) and radionuclide purity of 98%. (46)Sc-DOTMP was prepared and an activity of 1.258 MBq (34 μCi) at a chelant-to-metal ratio of 60:1 was administered to five groups of mice with each group containing 3 mice that were euthanized at 4, 24, 48, 96 and 192 h post administration. The heart, lungs, liver, spleen, kidneys, intestine, skin, muscle, and a femur were excised, weighed, and counted. The data were analyzed to determine skeletal uptake and source organ residence times and cumulated activities for (47)Sc-DOTMP. (46)Sc-DOTMP complex was prepared in radiochemical purity about 93%. In vitro stability of complex was evaluated at room temperature for 48 h. Biodistribution studies of complex in mice were studied for 7 days. The data were analyzed to estimate skeletal uptake and absorbed radiation dose of human organs using biodistribution data from mice. By considering the results, (47)Sc-DOTMP is a possible therapeutic agent for using in palliation of bone pain due to metastatic skeletal lesions from several types of primary cancers in prostate, breast, etc.

Radiofrequency ablation and vertebral augmentation for palliation of painful spinal metastases

Radiofrequency ablation (RFA) and vertebral augmentation is an emerging combination therapy for painful osseous metastases that cannot be or are incompletely palliated with radiation therapy. Herein, we report our experience performing RFA and vertebral augmentation of spinal metastases for pain palliation. Institutional review board approval was obtained to retrospectively review our tumor ablation database for all patients who underwent RFA of osseous metastases between April 2012 and July 2014. Patient demographics, lesion characteristics, concurrent palliative therapies, and complications were recorded. Pre- and post-procedure mean worst pain scores 1 and 4 weeks after treatment were measured using the Numeric Rating Scale (10-point scale) and compared. During the study period, 72 RFA treatments of 110 spinal metastases were performed. Eighty one percent (89/110) of metastases involved the posterior vertebral body and 45 % (49/110) involved the pedicles. Vertebral augmentation was performed after 95 % (105/110) of ablations. Mean and median pre-procedure pain scores were 8.0 ± 1.9 and 8.0, respectively. Patients reported clinically significant decreased pain scores at both 1-week (mean, 3.9 ± 3.0; median, 3.25; P < 0.0001) and 4-week (mean, 2.9 ± 3.0; median, 2.75; P < 0.0001) follow-up. No major complications occurred related to RFA and there were no instances of symptomatic cement extravasation. Combination RFA and vertebral augmentation is a safe and effective therapy for palliation of painful spinal metastases, including tumor involving the posterior vertebral body and/or pedicles.

Well-designed bone-seeking radiolabeled compounds for diagnosis and therapy of bone metastases

Bone-seeking radiopharmaceuticals are frequently used as diagnostic agents in nuclear medicine, because they can detect bone disorders before anatomical changes occur. Furthermore, their effectiveness in the palliation of metastatic bone cancer pain has been demonstrated in the clinical setting. With the aim of developing superior bone-seeking radiopharmaceuticals, many compounds have been designed, prepared, and evaluated. Here, several well-designed bone-seeking compounds used for diagnostic and therapeutic use, having the concept of radiometal complexes conjugated to carrier molecules to bone, are reviewed.

Production cross–section calculations of medical 32P, 117Sn, 153Sm and 186,188Re radionuclides used in bone pain palliation treatment

In this study, production cross–section calculations of 32P, 117Sn, 153Sm and 186,188Re radionuclides used in bone pain palliation treatment produced by 30Si(d,γ)32P, 118Sn(γ,n)117Sn, 116Sn(n,γ)117Sn, 150Nd(α,n)153Sm, 154Sm(n,2n)153Sm, 152Sm(n,γ)153Sm, 186W(d,2n)186Re, 187Re(γ,n)186Re, 185Re(n,γ)186Re and 187Re(n,γ)188Re reactions have been investigated in the different incident energy range of 0.003–34 MeV. Two-component exciton and generalised superfluid models of the TALYS 1.6 and exciton and generalised superfluid models of the EMPIRE 3.1 computer codes have been used to pre-equilibrium (PEQ) reaction calculations. The calculated production cross–section results have been compared with available experimental results existing in the experimental nuclear reaction database (EXFOR). Except the 118Sn(γ,n)117Sn, 150Nd(α,n)153Sm and 185Re(n,γ)186Re reactions, the two-component exciton model calculations of TALYS 1.6 code exhibit generally good agreement with the experimental measurements for all reactions used in this present study.