Radiopharmaceuticals for palliation of painful osseous metastases

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.

Molecular target therapy for bone metastasis: starting a new era with denosumab, a RANKL inhibitor

INTRODUCTION

The skeleton is generally the primary, and sometimes the only, site of metastasis in patients with advanced solid tumors. Bone metastases are the most frequent cause of cancer-related pain and the origin of severe morbidity in patients. Among the treatment options available for the prevention of skeletal-related events (SREs) associated with bone metastasis, zoledronic acid, an antiresorptive treatment from the group of bisphosphonates, is currently the standard of care in this setting.

AREAS COVERED

Zoledronic acid, together with denosumab (a monoclonal antibody against the receptor activator of nuclear factor kappa B ligand), is the most frequent approach for the prevention of cancer-related events in skeleton. This paper reviews several trials evaluating the efficacy of denosumab in comparison with zoledronic acid in patients with solid osteotropic tumors. In this setting of skeleton-invading cancers, denosumab was demonstrated to be superior to zoledronic acid in preventing or delaying SREs. In comparison with zoledronic acid, denosumab significantly delayed the time to first SRE by 17%.

EXPERT OPINION

Current research on denosumab is addressed to prove the immunomodulator effect of this agent in humans. Other avenue of research is focused on its antitumor activity observed in some Phase III trials.

Painful boney metastases

Boney metastasis may lead to terrible suffering from debilitating pain. The most likely malignancies that spread to bone are prostate, breast, and lung. Painful osseous metastases are typically associated with multiple episodes of breakthrough pain which may occur with activities of daily living, weight bearing, lifting, coughing, and sneezing. Almost half of these breakthrough pain episodes are rapid in onset and short in duration and 44% of episodes are unpredictable. Treatment strategies include: analgesic approaches with "triple opioid therapy", bisphosphonates, chemotherapeutic agents, hormonal therapy, interventional and surgical approaches, steroids, radiation (external beam radiation, radiopharmaceuticals), ablative techniques (radiofrequency ablation, cryoablation), and intrathecal analgesics.

Influence of human biokinetics of strontium on internal ingestion dose of 90Sr and absorbed dose of 89Sr to organs and metastases

The objective of the present work is to apply the plasma clearance parameters to strontium, previously determined in our laboratory, to improve the biokinetic and dosimetric models of strontium-90 ((90)Sr) used in radiological protection; and also to apply this data for the estimation of the radiation doses from strontium-89 ((89)Sr) after administration to patients for the treatment of the painful bone metastases. Plasma clearance and urinary excretion of stable strontium tracers of strontium-84 ((84)Sr) and strontium-86 ((86)Sr) were measured in GSF-National Research Center for Environment and Health (GSF) in 13 healthy German adult subjects after intravenous injection and oral administration. The biological half-life of strontium in plasma was evaluated from 49 plasma concentration data sets following intravenous injections. This value was used to determine the transfer rates from plasma to other organs and tissues. At the same time, the long-term retention of strontium in soft tissue and whole body was constrained to be consistent with measured values available. A physiological urinary path was integrated into the biokinetic model of strontium. Parameters were estimated using our own measured urinary excretion values. Retention and excretion of strontium were modeled using compartmental transfer rates published by the International Commission on Radiological Protection (ICRP), the SENES Oak Ridge Inc. (SENES), and the Urals Research Center for Radiation Medicine (TBM). The results were compared with values calculated by applying our GSF parameters (GSF). For the dose estimation of (89)Sr, a bone metastases model (GSF-M) was developed by adding a compartment, representing the metastases, into the strontium biokinetic model. The related parameters were evaluated based on measured data available in the literature. A set of biokinetic parameters was optimized to represent not only the early plasma kinetics of strontium but also the long-term retention measured in soft tissue and whole body. The ingestion dose coefficients of (90)Sr were computed and compared with different biokinetic model parameters. The ingestion dose coefficients were calculated as 2.8 x 10(-8), 2.1 x 10(-8), 2.5 x 10(-8) and 3.8 x 10(-8) Sv Bq(-1) for ICRP, SENES, TBM and GSF model parameters, respectively. Moreover, organ absorbed dose for the radiopharmaceutical of (89)Sr in bone metastases therapy was estimated based on the GSF and ICRP biokinetic model parameters. The effective doses were 3.3, 1.8 and 1.2 mSv MBq(-1) by GSF, GSF-M, and ICRP Publication 67 model parameters, respectively, compared to the value of 3.1 mSv MBq(-1) reported by ICRP Publication 80. The absorbed doses of red bone marrow and bone surface, 17 and 21 mGy MBq(-1) calculated by GSF parameters, and 7.1 and 8.8 mGy MBq(-1) by GSF-M parameters, are comparable to the clinical results of 3-19 mGy MBq(-1) for bone marrow and 16 mGy MBq(-1) for bone surface. Based on the GSF-M model, the absorbed dose of (89)Sr to metastases was estimated to be 434 mGy MBq(-1). The strontium clearance half-life of 0.25 h from the plasma obtained in the present study is obviously faster than the value of 1.1 h recommended by ICRP. There are no significant changes for ingestion dose coefficients of (90)Sr using different model parameters. A model including the metastases was particularly developed for dose estimation of (89)Sr treatment for the pain of bone metastases.

Supportive Care in Lung Cancer

Lung cancer often is associated with significant morbidity, which has a detrimental effect on quality of life. Supportive care plays a central role in the multimodal treatment of lung cancer. Palliation of symptoms often improves quality of life and compliance with therapy. New developments in supportive care, reviewed here, include management of symptoms of the disease, such as respiratory problems, pain, and cachexia, as well as effects of treatment, including chemotherapy-induced nausea and vomiting, neutropenia, anemia, and mucositis. In the past few years, significant advances have been made in this field; however, palliation of the symptoms of lung cancer remains an area of active investigation.