153Sm-EDTMP for bone pain palliation in skeletal metastases

Recent Advances in 64Cu/67Cu-Based Radiopharmaceuticals

Copper-64 (T_1/2 = 12.7 h) is a positron and beta-emitting isotope, with decay characteristics suitable for both positron emission tomography (PET) imaging and radiotherapy of cancer. Copper-67 (T_1/2 = 61.8 h) is a beta and gamma emitter, appropriate for radiotherapy β-energy and with a half-life suitable for single-photon emission computed tomography (SPECT) imaging. The chemical identities of ⁶⁴Cu and ⁶⁷Cu isotopes allow for convenient use of the same chelating molecules for sequential PET imaging and radiotherapy. A recent breakthrough in ⁶⁷Cu production opened previously unavailable opportunities for a reliable source of ⁶⁷Cu with high specific activity and purity. These new opportunities have reignited interest in the use of copper-containing radiopharmaceuticals for the therapy, diagnosis, and theranostics of various diseases. Herein, we summarize recent (2018-2023) advances in the use of copper-based radiopharmaceuticals for PET, SPECT imaging, radiotherapy, and radioimmunotherapy.

177Lu-EDTMP for Metastatic Bone Pain Palliation: A Systematic Review and Meta-Analysis

Purpose: Painful metastatic bone involvement is common in advanced stages of many cancers. Between available radionuclides for bone pain palliation, no consensus has been reached on lutetium ethylenediaminetetramethylene phosphonate (¹⁷⁷Lu-EDTMP) administration in this milieu. The aim of this study is to evaluate the treatment efficacy, safety profile, and toxicities of ¹⁷⁷Lu-EDTMP in patients with metastatic bone involvement, according to the published literature. Methods: A comprehensive literature search of PubMed/MEDLINE, Scopus, and Google Scholar databases was carried out to retrieve pertinent articles published until January 2019, concerning the clinical efficacy and safety of ¹⁷⁷Lu-EDTMP for bone pain palliative purposes. Results: Eight studies (172 patients) were included. This analysis revealed statistically significant effect of ¹⁷⁷Lu-EDTMP therapy on the visual analog score (4.84% (95% CI: 3.88-5.81; p < 0.001), bone palliative pain response (84%, 95% CI: 75%-90%; p < 0.001), and Karnofsky performance status (21%, 95% CI: 18%-24%; p < 0.001) overall (as well as in the high-dose and low-dose subgroups). Complete palliative pain response to treatment was observed in 32% (95% CI: 16%-53%) of patients receiving ¹⁷⁷Lu-EDTMP. Anemia was found to be the most common hematologic toxicity imposed by this therapeutic approach (grade I/II anemia in 24% (95% CI: 14%-38%; p < 0.001) and grade III/IV anemia in 19% (95% CI: 12%-28%; p < 0.001)). Conclusions: ¹⁷⁷Lu-EDTMP seems to have comparable efficacy and safety profile as that of the frequently administered radiopharmaceuticals for bone palliation. Therefore, this agent can be a good option for bone pain palliative purposes, in case of limited access to other bone palliative radiopharmaceuticals.

Targeted Palliative Radionuclide Therapy for Metastatic Bone Pain

Bone metastasis develops in multiple malignancies with a wide range of incidence. The presence of multiple bone metastases, leading to a multitude of complications and poorer prognosis. The corresponding refractory bone pain is still a challenging issue managed through multidisciplinary approaches to enhance the quality of life. Radiopharmaceuticals are mainly used in the latest courses of the disease. Bone-pain palliation with easy-to-administer radionuclides offers advantages, including simultaneous treatment of multiple metastatic foci, the repeatability and also the combination with other therapies. Several β¯- and α-emitters as well as pharmaceuticals, from the very first [⁸⁹Sr]strontium-dichloride to recently introduced [²²³Ra]radium-dichloride, are investigated to identify an optimum agent. In addition, the combination of bone-seeking radiopharmaceuticals with chemotherapy or radiotherapy has been employed to enhance the outcome. Radiopharmaceuticals demonstrate an acceptable response rate in pain relief. Nevertheless, survival benefits have been documented in only a limited number of studies. In this review, we provide an overview of bone-seeking radiopharmaceuticals used for bone-pain palliation, their effectiveness and toxicity, as well as the results of the combination with other therapies. Bone-pain palliation with radiopharmaceuticals has been employed for eight decades. However, there are still new aspects yet to be established.

IUPAC Periodic Table of the Elements and Isotopes (IPTEI) for the Education Community (IUPAC Technical Report)

The IUPAC (International Union of Pure and Applied Chemistry) Periodic Table of the Elements and Isotopes (IPTEI) was created to familiarize students, teachers, and non-professionals with the existence and importance of isotopes of the chemical elements. The IPTEI is modeled on the familiar Periodic Table of the Chemical Elements. The IPTEI is intended to hang on the walls of chemistry laboratories and classrooms. Each cell of the IPTEI provides the chemical name, symbol, atomic number, and standard atomic weight of an element. Color-coded pie charts in each element cell display the stable isotopes and the relatively long-lived radioactive isotopes having characteristic terrestrial isotopic compositions that determine the standard atomic weight of each element. The background color scheme of cells categorizes the 118 elements into four groups: (1) white indicates the element has no standard atomic weight, (2) blue indicates the element has only one isotope that is used to determine its standard atomic weight, which is given as a single value with an uncertainty, (3) yellow indicates the element has two or more isotopes that are used to determine its standard atomic weight, which is given as a single value with an uncertainty, and (4) pink indicates the element has a well-documented variation in its atomic weight, and the standard atomic weight is expressed as an interval. An element-by-element review accompanies the IPTEI and includes a chart of all known stable and radioactive isotopes for each element. Practical applications of isotopic measurements and technologies are included for the following fields: forensic science, geochronology, Earth-system sciences, environmental science, and human health sciences, including medical diagnosis and treatment.

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.

Separation of samarium and europium by solvent extraction with an undiluted quaternary ammonium ionic liquid: towards high-purity medical samarium-153

Long-lived europium-154 impurities are formed during the production of medical samarium-153 in a high-flux nuclear reactor. A method to separate these europium impurities from samarium was investigated using the hydrophobic quaternary ammonium ionic liquid Aliquat 336 nitrate. The separation method consists of the selective reduction of Eu³⁺ by zinc metal in an aqueous feed solution containing a high nitrate salt concentration. Subsequent extraction using undiluted Aliquat 336 nitrate leads to an efficient separation of both lanthanides in a relatively short time frame. Sm³⁺ was extracted to the neat ionic liquid phase much more efficiently than Eu²⁺. An initial approach using the addition of dicyclohexano-18-crown-6 to capture Eu²⁺ in the ionic liquid phase was less efficient.

After selective reduction of europium(iii), samarium is separated from europium by Aliquat 336 nitrate with high separation factors.

The importance of BMI in dosimetry of 153Sm-EDTMP bone pain palliation therapy: A Monte Carlo study

Using digital phantoms as an atlas compared to acquiring CT data for internal radionuclide dosimetry decreases patient overall radiation dose and reduces the required analysis effort and time for organ segmentation. The drawback is that the phantom may not match exactly with the patient. We assessed the effect of varying BMIs on dosimetry results for a bone pain palliation agent, ¹⁵³Sm-EDTMP. The simulation was done using the GATE Monte Carlo code. Female XCAT phantoms with the following different BMIs were employed: 18.6, 20.8, 22.1, 26.8, 30.3 and 34.7kg/m². S-factors (mGy/MBq.s) and SAFs (kg^-1) were calculated for the dosimetry of the radiation from major source organs including spine, ribs, kidney and bladder into different target organs as well as whole body dosimetry from spine. The differences in dose estimates from different phantoms compared to those from the phantom with BMI of 26.8kg/m² as the reference, were calculated for both gamma and beta radiations. The relative differences (RD) of the S-factors or SAFs from the values of reference phantom were calculated. RDs greater than 10% and 100% were frequent in radiations to organs for photon and beta particles, respectively. The relative differences in whole body SAFs from the reference phantom were 15.4%, 7%, 4.2%, -9.8% and -1.4% for BMIs of 18.6, 20.8, 22.1, 30.3 and 34.7kg/m², respectively. The differences in whole body S-factors for the phantoms with BMIs of 18.6, 20.8, 22.1, 30.3 and 34.7kg/m² were 39.5%, 19.4%, 8.8%, -7.9% and -4.3%, respectively. The dosimetry of the gamma photons and beta particles changes substantially with the use of phantoms with different BMIs. The change in S-factors is important for dose calculation and can change the prescribed therapeutic dose of ¹⁵³Sm-EDTMP. Thus a phantom with BMI better matched to the patient is suggested for therapeutic purposes where dose estimates closer to those in the actual patient are required.

Human absorbed dose estimation for a new (175)Yb-phosphonate based on rats data: Comparison with similar bone pain palliation agents

In this work, the absorbed dose to human organs for (175)Yb-BPAMD was evaluated based on the biodistribution studies in rats. The results showed that the bone surface would receive the highest absorbed dose after injection of (175)Yb-BPAMD with 13.32mGy/MBq, while the other organs receive insignificant absorbed dose. Also, the comparison of (175)Yb-BPAMD with other therapeutic phosphonate complexes demonstrated noticeable characteristics for this new agent. Generally, based on the obtained results, (175)Yb-BPAMD can be considered as a promising agent for bone pain palliative therapy in near future.

Metastatic Bone Pain Palliation using (177)Lu-Ethylenediaminetetramethylene Phosphonic Acid

¹⁷⁷Lu-ethylenediaminetetramethylene phosphonic acid (EDTMP) is presently suggested as an excellent bone seeking radionuclide for developing metastatic bone pain (MBP) palliation agent owing to its suitable nuclear decay characteristics. To find the exact dosage and its efficiency, this clinical study was performed on the human being, using ¹⁷⁷Lu-EDTMP for MBP palliation. ¹⁷⁷Lu-EDTMP was prepared by Iran, atomic energy organization. Thirty consecutive patients with determined tumors, incontrollable MBP, and positive bone scan at 4 weeks before the beginning of the study participated in this study in the nuclear medicine ward. ¹⁷⁷Lu-EDTMP in the form of sterile slow IV injection was administered with a dose of 29.6 MBq/kg. Short form of brief pain inventory questionnaire was used to evaluate the efficiency of the intervention. Questionnaires were filled out by an expert nuclear physician every 2 weeks while the cell blood count was also checked every 2 weeks up to 12 weeks for evaluation of bone marrow suppression and hematological toxicity. Furthermore, whole body scan was done at days 1, 3, and 7. Twenty-five patients showed a significant pain relief since 2 weeks after the injection, and continued until the end of the follow up period (12 weeks). There were no significant early complications such as bone marrow suppression, hematological toxicity, and no systemic adverse effects. No complication was observed in renal function. Twenty one patients showed flare phenomenon that was started after the 12.2 ± 1.78 h lasting for 38.4 ± 23.08. Sixteen patients (53%) were completely treated; nine patients (30%) showed a partial response, and five patients (17%) had no response to treatment. Total response to treatment was achieved in 25 patients (83%). At the end of the evaluation, no bone marrow suppression or hematologic toxicity was observed. ¹⁷⁷Lu-EDTMP has shown suitable physical and biological properties with good results in long term bone pain relief for patients with bone metastasis.

Study of Bone Surface Absorbed Dose in Treatment of Bone Metastases via Selected Radiopharmaceuticals: Using MCNP4C Code and Available Experimental Data

Bone metastases are major clinical concern that can cause severe problems for patients. Currently, various beta emitters are used for bone pain palliation. This study, describes the process for absorbed dose prediction of selected bone surface and volume-seeking beta emitter radiopharmaceuticals such as (32)P, (89)SrCl2,(90)Y-EDTMP,(153)Sm-EDTMP, (166)Ho-DOTMP, (177)Lu-EDTMP,(186)Re-HEDP, and (188)Re-HEDP in human bone, using MCNP code. Three coaxial sub-cylinders 5 cm in height and 1.2, 2.6, and 7.6 cm in diameter were used for bone marrow, bone, and muscle simulation respectively. The *F8 tally was employed to calculate absorbed dose in the MCNP4C simulations. Results show that with injection of 1 MBq of these radiopharmaceuticals given to a 70 kg adult man, (32)P, (89)SrCl2, and (90)Y-EDTMP radiopharmaceuticals will have the highest amount of bone surface absorbed dose, where beta particles will have the greatest proportion in absorbed dose of bone surface in comparison with gamma radiation. These results demonstrate moderate agreement with available experimental data.

The elements of life and medicines

Which elements are essential for human life? Here we make an element-by-element journey through the periodic table and attempt to assess whether elements are essential or not, and if they are, whether there is a relevant code for them in the human genome. There are many difficulties such as the human biochemistry of several so-called essential elements is not well understood, and it is not clear how we should classify elements that are involved in the destruction of invading microorganisms, or elements which are essential for microorganisms with which we live in symbiosis. In general, genes do not code for the elements themselves, but for specific chemical species, i.e. for the element, its oxidation state, type and number of coordinated ligands, and the coordination geometry. Today, the biological periodic table is in a position somewhat similar to Mendeleev's chemical periodic table of 1869: there are gaps and we need to do more research to fill them. The periodic table also offers potential for novel therapeutic and diagnostic agents, based on not only essential elements, but also non-essential elements, and on radionuclides. Although the potential for inorganic chemistry in medicine was realized more than 2000 years ago, this area of research is still in its infancy. Future advances in the design of inorganic drugs require more knowledge of their mechanism of action, including target sites and metabolism. Temporal speciation of elements in their biological environments at the atomic level is a major challenge, for which new methods are urgently needed.

Samarium-153 therapy for prostate cancer: the evaluation of urine activity, staff exposure and dose rate from patients

The aim of this study was to determine the excretion of Samarium-153-ethylenediaminetetramethylphosphonic acid ((153)Sm-EDTMP) in urine and to calculate the dose rate of its retention in the body as a function of time and the dose received by the skin of laboratory staff's finger. Urine samples were collected from 11 patients after intravenous injection of (153)Sm-EDTMP. The measurements of dose rate were performed. Thermoluminescent dosemeters were used for absorbed dose measurements. Effective half-lives that were calculated from urine sample measurements were found as 7.1±3 h within the first 24 h. Whole body dose rates before collecting urine of patients were 60.0 ± 15.7 µSv h(-1) for within 1 h following (153)Sm-EDTMP administration. The highest finger radiation dose is to the right-hand thumb (3.8 ± 2 mGy). The results of the study imply that patients who recieved (153)Sm-EDTMP therapy should be kept a minumum of 8 h in an isolated room at hospital and that one staff should give therapy at most two patients per week.

Production, quality control, and bio-distribution studies of (159)Gd-EDTMP as a palliative agent for bone pain

INTRODUCTION

Particle-emitting, bone-seeking radiopharmaceuticals have attracted the attention of the nuclear medicine community over the last three decades for the treatment of the pain of osteoblastic metastases. The objectives of this research were to produce quality-controlled (159)Gd-EDTMP in order to provide a new therapeutic radiopharmaceutical for use in clinical applications.

METHODS

The investigation was an experimental study in which (159)Gd (T1/2=18.479 h, Eβ (max)=970.60 keV, Eγ=363.55 (11.4%) keV] was produced by thermal neutron bombardment of natural Gd2O3 at the Tehran Research Reactor (TRR) for a period of 7 d at a flux of 3-4×10(13) neutrons/cm(2).s. It was then quality-controlled and used to radio-label the in-house prepared ethylene diamine tetra acetic acid (EDTM).

RESULTS

Complexation parameters were optimized to achieve maximum yields (>99%). The radiochemical purity of (159)Gd-EDTMP was checked by radio thin layer chromatography RTLC. It was found to retain its stability at room temperature (>95%). Bio-distribution studies of the complexes conducted in wild rats showed significant bone uptake with rapid clearance from blood.

CONCLUSION

The properties of the (159)Gd-EDTMP that was produced suggest then use of a new, efficient, palliative therapeutic agent for metastatic bone pain instead of some other current radiopharmaceuticals.

Improving the dose-myelotoxicity correlation in radiometabolic therapy of bone metastases with 153Sm-EDTMP

PURPOSE

(153)Sm-ethylene diamine tetramethylene phosphonic acid ((153)Sm-EDTMP) is widely used to palliate pain from bone metastases, and is being studied for combination therapy beyond palliation. Conceptually, red marrow (RM) dosimetry allows myelotoxicity to be predicted, but the correlation is poor due to dosimetric uncertainty, individual sensitivity and biological effects from previous treatments. According to EANM guidelines, basic dosimetric procedures have been studied to improve the correlation between dosimetry and myelotoxicity in (153)Sm-EDTMP therapy.

METHODS

RM dosimetry for 33 treatments of bone metastases from breast, prostate and lung tumours was performed prospectively (with (99m)Tc-MDP) and retrospectively, acquiring whole-body scans early and late after injection. The (153)Sm-EDTMP activity was calculated by prospective dosimetry based on measured skeletal uptake and full physical retention, with the RM absorbed dose not exceeding 3.8 Gy. Patient-specific RM mass was evaluated by scaling in terms of body weight (BW), lean body mass (LBM) and trabecular volume (TV) estimated from CT scans of the L2–L4 vertebrae. Correlations with toxicity were determined in a selected subgroup of 27 patients, in which a better correlation between dosimetry and myelotoxicity was expected.

RESULTS

Skeletal uptakes of (99m)Tc and (153)Sm (Tc% and Sm%) were well correlated. The median Sm% was higher in prostate cancer (75.3 %) than in lung (60.5%, p = 0.005) or breast (60.8%, p = 0.008). PLT and WBC nadirs were not correlated with administered activity, but were weakly correlated with uncorrected RM absorbed doses, and the correlation improved after rescaling in terms of BW, LBM and TV. Most patients showed transient toxicity (grade 1–3), which completely and spontaneously recovered over a few days. Using TV, RM absorbed dose was in the range 2–5 Gy, with a median of 312 cGy for PLT in patients with toxicity and 247 cGy in those with no toxicity (p = 0.019), and 312 cGy for WBC in those with toxicity and 232 cGy in those with no toxicity (p = 0.019). ROC curves confirmed the correlations, yielding toxicity absorbed dose thresholds of 265 cGy for PLT and 232 cGy for WBC.

CONCLUSION

The best predictor of myelotoxicity and blood cells nadir was obtained scaling the RM absorbed dose in terms of the estimated TV. It seems clear that the increase in skeletal uptake due to the presence of bone metastases and the assumption of full physical retention cause an overestimation of the RM absorbed dose. Nevertheless, an improvement of the dose–toxicity correlation is easily achievable by simple methods, also leading to possible improvement in multifactorial analyses of myelotoxicity.

(177)Lu-EDTMP for palliation of pain from bone metastases in patients with prostate and breast cancer: a phase II study

PURPOSE

The purpose of this study was to evaluate the efficacy and safety of (177)Lu-EDTMP for pain palliation in patients with bone metastases from castration-resistant prostate and breast cancer. The secondary objective was to compare low-dose and high-dose (177)Lu-EDTMP in bone pain palliation.

METHODS

Included in the study were 44 patients with documented breast carcinoma (12 patients; age 47 ± 13 years) or castration-resistant prostate carcinoma (32 patients; age 66 ± 9 years) and skeletal metastases. Patients were randomized into two equal groups treated with (177)Lu-EDTMP intravenously at a dose of 1,295 MBq (group A) or 2,590 MBq (group B). Pain palliation was evaluated using a visual analogue score (VAS), analgesic score (AS) and Karnofsky performance score (KPS) up to 16 weeks. Toxicity was assessed in terms of haematological and renal parameters.

RESULTS

The overall response rate (in all 44 patients) was 86 %. Complete, partial and minimal responses were seen in 6 patients (13 %), 21 patients (48 %) and 11 patients (25 %), respectively. A favourable response was seen in 27 patients (84 %) with prostate cancer and in 11 patients (92 %) with breast cancer. There was a progressive decrease in the VAS from baseline up to 4 weeks (p < 0.05). Also, AS decreased significantly from 1.8 ± 0.7 to 1.2 ± 0.9 (p < 0.0001). There was an improvement in quality of life of the patients as reflected by an increase in mean KPS from 56 ± 5 to 75 ± 7 (p < 0.0001). The overall response rate in group A was 77 % compared to 95 % in group B (p = 0.188). There was a significant decrease in VAS and AS accompanied by an increase in KPS in both groups. Nonserious haematological toxicity (grade I/II) was observed in 15 patients (34 %) and serious toxicity (grade III/IV) occurred in 10 patients (23 %). There was no statistically significant difference in haematological toxicity between the groups.

CONCLUSION

(177)Lu-EDTMP was found to be a safe and effective radiopharmaceutical for bone pain palliation in patients with metastatic prostate and breast carcinoma. There were no differences in efficacy or toxicity between patients receiving low-dose and high-dose (177)Lu-EDTMP.

New treatment option: 223Ra chloride, the first approved unsealed α-emitting radiopharmaceutical

A 66-year-old man with prostate cancer presented with intractable pain associated with multifocal bone metastases. After receiving 180 µCi (1.35 µCi/kg) of (223)Ra chloride, radiation survey measured 0.2 mR/h at 1 m, and the patient was discharged to home. He will return monthly for the next 5 months for repeat (223)Ra chloride administrations. (223)Ra chloride is the first Food and Drug Administration-approved unsealed α-emitting radiopharmaceutical.

Pain palliative therapy in women with breast cancer osseous metastatic disease and the role of specific serum cytokines as prognostic factors

PURPOSE

To evaluate the efficacy of radionuclide palliative therapy (RPT) in women suffering from painful metastatic bone disease (MBD) due to breast cancer (BrCa), and to investigate the possible relationship between the RPT efficacy and cytokines levels.

METHODS

Sixty-three BrCa women patients with MBD enrolled in a prospective, nonrandomized study. Thirty were treated with Rhenium-186-hydroxyethylidenediphosphonic acid ((186)Re-HEDP), 21 with Strontium-89-Chloride ((89)Sr-Cl2), and 12 with Samarium-153-thylenediaminetetramethylenephosphonic acid ((153)Sm-EDTMP). Blood samples were collected pre- and post-therapy to assess the interleukin (IL)-2, IL-6 and tumor necrosis factor (TNF)-a titers. The palliative effect of the treatment was evaluated using a modified Wisconsin test.

RESULTS

All three radiopharmaceuticals were equally effective in pain relief. Pain palliation was complete in 52% of patients, partial in 31%, and absent in 16%. Responders to therapy had higher IL-2 and lower IL-6/TNF-a concentrations, compared with nonresponders, even though statistically significant difference in cytokines levels between responders and nonresponders before treatment was noted only for IL-6.

CONCLUSION

All used radiopharmaceuticals had the same therapeutic effect. Pretherapy low titers of IL-6 levels seems to have a favorable prognostic value for the therapeutic outcome, while IL-2 and TNF-a alterations pre- and post-therapy can only serve as markers of a better RPT response.

Production, quality control and biodistribution studies of thulium-170-labeled ethylenediamine (tetramethylene phosphonic acid)

Thulium-170 (T 1/2 = 128.4 d, E β (max) = 968 keV, E γ = 84 keV (3.26%)) has radionuclidic properties suitable to be used in palliative therapy of bone metastases as an alternative to 89SrCl2. 170Tm can be produced by a relatively easy route involving thermal neutron bombardment on natural Tm2O3 (100% 169Tm) in medium flux research reactors. The requirement for an enriched target does not arise and radionuclidic impurities are not formed by radiative capture during neutron activation. In this study 170Tm was produced using Tm(NO3)3, prepared by neutron activation (3–4E13) of a natural sample. Ethylenediamine (tetramethylene phosphonic acid) (EDTMP) was synthesized and radiolabeled with 170Tm. Complexation parameters were optimized to achieve maximum yields (>99%). The radiochemical purity of 170Tm-EDTMP was checked by RTLC. It was found to retain its stability at room temperature even after 2 months of preparation (> 95%). Biodistribution studies of the complexes carried out in wild-type rats showed significant bone uptake with rapid clearance from blood. The properties of produced 170Tm-EDTMP suggest applying a new efficient bone pain palliative therapeutic agent in the country instead of some other in-use radiopharmaceuticals, such as 89SrCl2 and 32P, in order to overcome metastatic bone pains.

In the field: exploiting the untapped potential of immunogenic modulation by radiation in combination with immunotherapy for the treatment of cancer

Radiation has long been the standard of care for many types of cancer. It is employed to locally eradicate tumor cells as well as alter tumor stroma with either curative or palliative intent. Radiation-induced cell damage is an immunologically active process in which danger signals are released that stimulate immune cells to phagocytose and present locally released tumor-associated antigens (TAAs). Recent studies have indicated that radiotherapy can also alter the phenotype of cancer cells that remain after treatment. These cells upregulate TAAs as well as markers, including major histocompatibility complex and costimulatory molecules, that make them much more immunostimulatory. As our understanding of the immunomodulatory effects of radiation has improved, interest in combining this type of therapy with immune-based therapies for the treatment of cancer has grown. Therapeutic cancer vaccines have been shown to initiate the dynamic process of host immune system activation, culminating in the recognition of host cancer cells as foreign. The environment created after radiotherapy can be exploited by active therapeutic cancer vaccines in order to achieve further, more robust immune system activation. This review highlights preclinical studies that have examined the alteration of the tumor microenvironment with regard to immunostimulatory molecules following different types of radiotherapy, including external beam radiation, radiolabeled monoclonal antibodies, bone-seeking radionuclides, and brachytherapy. We also emphasize how combination therapy with a cancer vaccine can exploit these changes to achieve improved therapeutic benefit. Lastly, we describe how these laboratory findings are translating into clinical benefit for patients undergoing combined radiotherapy and cancer vaccination.

The tipping point for combination therapy: cancer vaccines with radiation, chemotherapy, or targeted small molecule inhibitors

Therapeutic cancer vaccines are a unique treatment modality in that they initiate a dynamic process of activating the host immune system, which can then be exploited by concurrent or subsequent therapies. The addition of immunotherapy to standard-of-care cancer therapies has shown evidence of efficacy in preclinical models and in the clinical setting. This review examines the preclinical and clinical interactions between vaccine-mediated tumor-specific immune responses and local radiation, systemic chemotherapy, or select small molecule inhibitors, as well as the potential synergy between these modalities.

Ethylene diamine tetramethylene phosphonic acid labeled with various β(-)-emitting radiometals: labeling optimization and animal biodistribution

Skeletal uptake of β(-)-emitting radionuclides may be used for bone pain palliation or myeloablation. The physical characteristics of the β(-) particles required for the two conditions are, however, different, that is, higher energies are favorable for destruction of bone marrow. In this study, the labeling conditions of ethylene diamine tetramethylene phosphonic acid (EDTMP) with three rare earth metals (90Y, 166Ho, and 177Lu) having β(-) particles of diverse physical characteristics were optimized, and their animal biodistributions were studied and compared with 153Sm-EDTMP. All the four radiometals (X =  90Y, 166Ho, 177Lu, and 153Sm) were produced from n,γ reactions of their respective precursors (89Y, 165Ho, 176Lu, and 152Sm). They were labeled with EDTMP at varying degrees of pH and molar ratios, and labeling yields were determined by paper chromatography at each data point. The complexes with optimal labeling yields and their chloride forms (XCl3) were then studied for biodistributions in 66 Sprague-Dawley male rats at 30 minutes, 2 hours, and 24 hours after injection. All the radiopharmaceuticals gave ∼98% complex yields at pH 8. At optimum pH level, good labeling was achieved at X:EDTMP molar ratios of 1:5, 1:8, and 1:20 for 90Y, 166Ho, and 177Lu complexes, respectively. 177Lu-EDTMP showed the best biodistribution results among all the complexes, with a total skeletal uptake of 70.2%  ± 2.4% at 24 hours ((153)Sm-EDTMP = 59.1%  ±  2.6%). 90Y-EDTMP had skeletal accumulation significantly higher than (166)Ho-EDTMP (45.5%  ± 2.9% and 27.4%  ±  3.6%, respectively). Blood activity of all the agents disappeared promptly through the kidneys. This study demonstrates higher localization of 177Lu-EDTMP in skeleton than 153Sm-EDTMP and shows that the localization of 90Y-EDTMP is better among the high-energy radiometals studied.

Biological evaluation of 153Sm and 166Ho complexes with tetraazamacrocycles containing methylcarboxylate and/or methylphosphonate pendant arms

153Sm and 166Ho complexes with two series of tetraazamacrocyclic ligands containing methylcarboxylate and/or methylphosphonate pendant arms were synthesized and their charge, lipophilicity, protein binding and in vitro and in vivo behaviour evaluated. The first series has the same backbone, a 14-membered tetraazamacrocycle containing a pyridine unit with different pendant arms, namely methylcarboxylates (ac3py14) or methylphosphonates (MeP2py14 and P3py14). The second series comprises 12- to 14-membered tetraazamacrocycles having methylcarboxylates and/or methylphosphonates as pendant arms (trans-DO2A2P, TRITA, TRITP, TETA and TETP). The 153Sm/166Ho complexes with the 14-membered tetraazamacrocycles containing the pyridine unit are neutral, hydrophilic, have a significant plasmatic protein binding, are unstable in vivo and present a slow rate of radioactivity excretion and high hepatic retention. 153Sm/166Ho complexes with the 12- to 14-membered tetraazamacrocycles are quantitatively prepared, except those with TETP. These complexes are hydrophilic, have an overall negative charge and present a medium to low plasmatic protein binding.

The 153Sm/166Ho- trans-DO2A2P, 153Sm/166Ho-TRITA and 166Ho-TRITP complexes are stable in vitro and in vivo, presenting a rapid clearance from main organs and a high rate of whole body radioactivity excretion. Biological profile of 153Sm/166Ho-TRITA complexes makes them promising candidates for therapy when conjugated to a biomolecule, while 166Ho-TRITP is potentially useful for bone targeting due to its considerable uptake by bone.

177Lu-DOTMP: A viable agent for palliative radiotherapy of painful bone metastasis

The suitable nuclear decay characteristics [T 1/2=6.73 d, E β (max)=497 keV, E γ=113 keV (6.4%), 208 keV (11%)] as well as the feasibility of large-scale production with adequate specific activity and radionuclidic purity using a moderate flux reactor are important attributes towards 177Lu to be considered as a promising radionuclide for palliative care in painful bone metastasis. The present study describes the preparation of 177Lu complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid (DOTMP) and its preliminary biological evaluation in animal models with an aim to proposing it as a viable radiopharmaceutical for bone pain palliation. The choice DOTMP as the polyaminophosphonic acid carrier ligand is based on the enhanced thermodynamic stability and kinetic inertness of the metal-ligand complexes with macrocyclic chelators. 177Lu was produced with a specific activity of ∼12 GBq/mg (∼324 mCi/mg) and radionuclidic purity of 99.98% by irradiation of natural Lu2O3 target at a thermal neutron flux of ∼6×1013 n/cm2s for 21 d. 177Lu-DOTMP complex was prepared in high yield and excellent radiochemical purity (>99%) using DOTMP synthesized and characterized in-house. The complex exhibited excellent in-vitro stability at room temperature. Biodistribution studies in Wistar rats showed rapid skeletal accumulation of the injected activity [(1.60±0.19) per gram in femur at 3 h post-injection] with fast clearance from blood and minimal uptake in any of the major organs. Scintigraphic studies carried out in normal Wistar rats and New Zealand white rabbits also demonstrated significant accumulation of the agent in skeleton and almost no retention in any other vital organs.

Percutaneous tumor curettage and interstitial delivery of samarium-153 coupled with kyphoplasty for treatment of vertebral metastases

Object

The object of this study was to investigate the use of a minimally invasive technique for treating metastatic tumors of the vertebral body, aimed at relieving pain, preventing further tumor growth, and minimizing the adverse effects of systemic use of samarium-153 (153Sm).

Methods

The procedure is performed in the same fashion as a kyphoplasty, using a unilateral extrapedicular approach under local anesthesia/mild general sedation, with the patient in the lateral decubitus position. The tumor is accessed as in a standard kyphoplasty. The side is chosen according to the location of the metastasis. Prior to inflation of the balloon the tumor is debulked by percutaneous curettage. Balloon inflation is carried out as per standard kyphoplasty in an attempt to create a larger space and reduce a possible kyphotic deformity. Three mCi of 153Sm-EDTMP (ethylenediaminetetramethylenephosphonic acid) is then mixed with bone cement (polymethylmethacrylate) and injected into the void created by the balloon tamp.

Results

Twenty-four procedures were performed in 19 patients. There was reliable and reproducible delivery of the radiolabeled 153Sm-EDTMP to the metastatic site, without spillage. The procedure was safe. There were no procedure-related complications. There was no hematological toxicity with the low doses of 153Sm used. Pain improved in all patients. The long-term results related to tumor control continue to be investigated.

Conclusions

Combined percutaneous debulking of confined vertebral metastases and administration of local 153Sm is feasible and safe. Furthermore, this technique leads to immediate relief of cancer-related pain and may help prevent or slow down the progression of vertebral metastatic tumors.

Pain therapy

Cancer-related pain is a major issue of healthcare systems worldwide. The reported incidence, considering all stages of the disease, is 51%, which can increase to 74% in the advanced and terminal stages. For advanced cancer, pain is moderate to severe in about 40-50% and very severe or excruciating in 25-30% of cases. Pain is both a sensation and an emotional experience. Pain is always subjective; and may be affected by emotional, social and spiritual components thus it has been defined as "total pain". From a pathophysiological point of view, pain can be classified as nociceptive (somatic and visceral), neuropathic (central, peripheral, sympathetic) idiopathic or psychogenic. A proper pain assessment is fundamental for an effective and individualised treatment. In 1986 the World Health Organisation (WHO) published analgesic guidelines for the treatment of cancer pain based on a three-step ladder and practical recommendations. These guidelines serve as an algorithm for a sequential pharmacological approach to treatment according to the intensity of pain as reported by the patient. The WHO analgesic ladder remains the clinical model for pain therapy. Its clinical application should be employed only after a complete and comprehensive assessment and evaluation based on the needs of each patient. When applying the WHO guidelines, up to 90% of patients can find relief regardless of the settings of care, social and/or cultural environment. This is the standard treatment on a type C basis. Only when such an approach is ineffective are interventions such as spinal administration of opioid analgesics or neuroinvasive procedures recommended.

153Sm: its use in multiple myeloma and report of a clinical experience

BACKGROUND

In the past years the bone seeking radiopharmaceutical samarium lexidronam ((153)Sm-EDTMP) has been increasingly used alone or in conjunction with chemotherapy and/or bisphosphonates for the treatment of painful bone metastasis.

OBJECTIVE

Its use has been explored in different solid tumours. In this report we explore its interesting characteristics and describe our experience in multiple myeloma (MM).

METHODS

(153)Sm-EDTMP has an affinity for bone and concentrates in areas of bone turnover. It decays as a therapeutic beta-emission and at the same time as gamma-photon that can be used for tracking its concentration with bone scan imaging. Ten patients with symptomatic MM were treated to achieve pain control.

RESULTS

Encouraging results were obtained in MM patients. The use of this radioisotope could be largely improved.

Imaging atoms in medicine

The innovations in science and technology have allowed researchers to look inside the human body. In some cases, like MRI, the protons present in the body generate enough signal for an image. However, the employ of certain atoms, metallic or non-metallic, enable detection through different imaging techniques (computed tomography, nuclear imaging, ultrasound or optical imaging), and improve the quality of the images. Here we discuss the different imaging atoms used depending on the imaging technique and the new possible imaging atoms for medical applications.

Prospective dosimetry with 99mTc-MDP in metabolic radiotherapy of bone metastases with 153Sm-EDTMP

PURPOSE

On the basis of the encouraging results achieved in several clinical trials and its proven therapeutic efficacy, (153)Sm-ethylene diamine tetramethylene phosphonic acid (EDTMP) has become widely used to palliate pain from bone metastases. The results reported in the literature have led the product suppliers (QUADRAMET, Schering) to suggest administering a fixed activity per kilogram (37 MBq/kg). However, considering the observed extreme inter-patient variability of skeletal uptake of (153)Sm-EDTMP, a real therapy optimization would require the individualization of the activity to be administered on a dosimetric basis. This should be planned taking into account the generally accepted 2-Gy dose constraint to the haematopoietic red marrow, the critical organ in palliative treatments with beta-emitting, bone-seeking radiopharmaceuticals.

METHODS

Seven to 14 days before treatment with (153)Sm-EDTMP, 44 patients underwent (99m)Tc-methylene diphosphonate (MDP) total-body bone scan with two scans (the first within 10 min of injection, the second after 6 h). The percentage bone uptake (Tc(%)) was evaluated as the ratio between total counts at 6 h, adjusted for decay, and total counts at the first scan. Tc(%) was then compared to Sm(%) similarly derived from 10-min and 24-h whole-body scans. Tc(%) and Sm(%) were compared both with and without Brenner's method for soft tissue uptake.

RESULTS

The correlation between Tc(%) and Sm(%) was R (2) = 0.81 and R (2) = 0.88 with and without soft tissue correction, respectively. The difference between their average values was statistically significant (Sm(%) = 64.3 +/- 15.2, Tc(%) = 56.2 +/- 16.0; p = 0.017) with soft tissue correction, while was not statistically significant (Sm(%) = 68.2 +/- 15.5, Tc(%) = 66.9 +/- 14.0; p = 0.670) without soft tissue correction.

CONCLUSIONS

The rate of retention of (99m)Tc-MDP in bone provides a reliable estimate of the (153)Sm-EDTMP rate of retention. The proposed method can be usefully adopted for prospective dosimetry seeing its extreme simplicity, and it requires no special investment in terms of human or instrumental resources. This allows an optimization of administered (153)Sm-EDTMP activity.

177Lu-EDTMP: a viable bone pain palliative in skeletal metastasis

Designing ideal radiopharmaceuticals for use as bone pain palliatives require the use of a moderate energy beta() emitter as a radionuclide and a suitable polyaminophosphonic acid as a carrier molecule. Owing to its suitable decay characteristics [T(1/2) = 6.73 d, E((max)) = 497 keV, E() = 113 keV (6.4%), 208 keV (11%)] as well as the feasibility of large-scale production in adequate specific activity and radionuclidic purity using a moderate flux reactor, 177Lu could be considered as a promising radionuclide for palliative care in painful bone metastasis. The present study was therefore, oriented toward the preparation and biologic evaluation of 177Lu complex of ethylenediaminetetramethylene phosphonic acid (EDTMP) in various animal models, with an aim to prepare a viable radiopharmaceutical for bone pain palliation. 177Lu was produced with a specific activity of approximately 12 GBq/mg (approximately 324 mCi/mg) and radionuclidic purity of 99.98% by irradiation of natural Lu2O3 targeted at a thermal neutron flux of approximately 6 x 10(13) n/cm(2).s for 21 days. 177Lu-EDTMP complex was prepared in high-yield and excellent radiochemical purity (>99%), using EDTMP synthesized and characterized in-house. The complex exhibited excellent in vitro stability at room temperature. Biodistribution studies in Wistar rats showed a rapid skeletal accumulation of injected activity [(1.74 +/- 0.30)% per gram in femur at 3 hours postinjection] with a fast clearance from blood and minimal uptake in any of the major organs. Scintigraphic imaging studies carried out in normal Wistar rats, New Zealand white rabbits, as well as in Beagle dogs also demonstrated significant accumulation of the agent in the skeleton and almost no retention of activity in any other vital organs.

The use of chelated radionuclide (samarium-153-ethylenediaminetetramethylenephosphonate) to modulate phenotype of tumor cells and enhance T cell-mediated killing

PURPOSE

Exposing human tumor cells to sublethal doses of external beam radiation up-regulates expression of tumor antigen and accessory molecules, rendering tumor cells more susceptible to killing by antigen-specific CTLs. This study explored the possibility that exposure to palliative doses of a radiopharmaceutical agent could alter the phenotype of tumor cells to render them more susceptible to T cell-mediated killing.

EXPERIMENTAL DESIGN

Here, 10 human tumor cell lines (4 prostate, 2 breast, and 4 lung) were exposed to increasing doses of the radiopharmaceutical samarium-153-ethylenediaminetetramethylenephosphonate ((153)Sm-EDTMP) used in cancer patients to treat pain due to bone metastasis. Fluorescence-activated cell sorting analysis and quantitative real-time PCR analysis for expression of five surface molecules and several tumor-associated antigens involved in prostate cancer were done. LNCaP human prostate cancer cells were exposed to (153)Sm-EDTMP and incubated with tumor-associated antigen-specific CTL in a CTL killing assay to determine whether exposure to (153)Sm-EDTMP rendered LNCaP cells more susceptible to T cell-mediated killing.

RESULTS

Tumor cells up-regulated the surface molecules Fas (100% of cell lines up-regulated Fas), carcinoembryonic antigen (90%), mucin-1 (60%), MHC class I (50%), and intercellular adhesion molecule-1 (40%) in response to (153)Sm-EDTMP. Quantitative real-time PCR analysis revealed additional up-regulated tumor antigens. Exposure to (153)Sm-EDTMP rendered LNCaP cells more susceptible to killing by CTLs specific for prostate-specific antigen, carcinoembryonic antigen, and mucin-1.

CONCLUSIONS

Doses of (153)Sm-EDTMP equivalent to palliative doses delivered to bone alter the phenotype of tumor cells, suggesting that (153)Sm-EDTMP may work synergistically with immunotherapy to increase the susceptibility of tumor cells to CTL killing.

Comparative studies of 177Lu-EDTMP and 177Lu-DOTMP as potential agents for palliative radiotherapy of bone metastasis

(177)Lu is presently considered as an excellent radionuclide for developing bone pain palliation agents owing to its suitable nuclear decay characteristics [T(1/2)=6.73d, E(beta)((max))=497keV, E(gamma)=113keV (6.4%) and 208keV (11%)] and large-scale production feasibility with adequate specific activity using moderate flux research reactors. Multidentate polyaminophosphonic acids have already been proven as the carrier molecule of choice for radiolanthanides and similar +3 metal ions in designing agents for palliative radiotherapy of bone pain due to skeletal metastases. The present paper describes a comparison between (177)Lu complexes of two potential polyaminophosphonic acid ligands, namely Ethylenediaminetetramethylene phosphonic acid (EDTMP) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid (DOTMP) with respect to their radiochemical and in-vivo biological characteristics. Although both the agents have exhibited promising features, the study reveals that (177)Lu-EDTMP has marginally higher skeletal accumulation in comparison to that of (177)Lu-DOTMP, while the latter has slightly faster blood clearance along with lower retention in liver and kidneys in animal models.

A comparative study of 188Re-HEDP, 186Re-HEDP, 153Sm-EDTMP and 89Sr in the treatment of painful skeletal metastases

AIM

The surface bone-seeking radiopharmaceuticals 188Re-HEDP, 186Re-HEDP and 153Sm-EDTMP, and the volume seeker 89Sr were investigated to determine the efficacy and toxicity in pain palliation of bone metastases.

METHOD

The effect of treatment with 188Re-HEDP, 186Re-HEDP, 153Sm-EDTMP and 89Sr on pain symptoms, quality of life, and bone marrow function were studied. In total, 79 patients (18 with breast cancer and 61 with prostate cancer) were treated (31 patients with 188Re-HEDP, 15 patients each with 186Re-HEDP and 153Sm-EDTMP, and 18 patients with 89Sr). All patients were interviewed using standardized sets of questions before and after therapy weekly for 12 weeks. Blood counts were taken weekly for 6 weeks and after 12 weeks.

RESULTS

In total, 73% of patients reported pain relief (77% after 188Re-HEDP, 67% after 186Re-HEDP 73% after 153Sm-EDTMP, and 72% after 89Sr). Fifteen percent of patients could discontinue their analgesics and were pain-free. Pain showed a decrease from 3.6+/-1.7 to a maximum of 2.2+/-1.8 at visual analogue scale in 10 steps (P<0.01). Patients described an improvement on the Karnofsky performance scale from 70+/-10% to 78+/-14% 12 weeks after treatment (P=0.15). There were eight patients with a thrombocytopenia grade I, two patients with grade II and one with grade III. The maximum nadir of platelet and leukocyte counts were observed between the 2nd to 5th week after treatment and was reversible within 12 weeks. There were no significant differences in pain palliation, Karnofsky performance status (KPS) and bone marrow toxicity between the different radionuclides (P=0.087-0.449).

CONCLUSION

All radiopharmaceuticals were effective in pain palliation, without induction of severe side effects or significant differences in therapeutic efficacy or toxicity.