Radium-223 dichloride is a radiopharmaceutical agent which, in combination with best standard of care (including androgen deprivation therapy), was shown to improve overall survival and time to first symptomatic skeletal event compared to placebo and best standard of care in patients with castration-resistant prostate cancer and symptomatic bone metastases without known visceral disease. Most of the energy from radium-223 is emitted as alpha-particles (95.3%), with a much smaller percentage as beta-particles (3.6%) and gamma-radiation (1.1%). Gamma-radiation allows for the measurement of radioactivity and detection of contamination with standard instruments. The specific activity of radium-223 is 1.9 MBq/ng (51.4 microcurie/ng), with typical treatment activity below 8,000 kBq (216 microcurie). Unlike gamma-radiation (blocked by lead or concrete) and beta-particles (blocked by aluminum), alpha-particles are unable to penetrate skin or paper; therefore, the radiation exposure associated with handling of patient doses is expected to be low. Radium-223 dichloride is FDA-approved for the treatment of castration-resistant prostate cancer in patients with symptomatic bone metastases and no known visceral metastases.
General Administration Information
For storage information, see the specific product information within the How Supplied section. Radium-223 dichloride (an alpha particle-emitting pharmaceutical) should only be received, used and administered by authorized persons in designated clinical settings, and is subject to the regulations and/or appropriate licenses of the competent official organization.
Route-Specific Administration
Injectable Administration
-Radium-223 dichloride is available in 6 mL single use vials containing 1,100 kBq/mL (30 microcurie/mL) at the reference date.
-Use universal precautions to avoid contamination, including gloves and barrier gowns, when handling blood and body fluids. Minimize the time spent in radiation areas, maximize the distance to radiation sources, and use adequate shielding
-In case of exposure to skin or eyes, flush immediately with water.
-In case of a spill, contact the local radiation safety officer immediately to begin decontamination procedures. Ethylene-diaminetetraacetic acid (EDTA, 0.01M) is recommended to remove contamination.
-There is a risk for radiation exposure or contamination from spills of bodily fluids (e.g., feces, urine, and vomit). Medical staff, caregivers, and patient's household members should take appropriate radiation protection precautions, including multiple flushes after using the toilet, washing soiled clothing separately from other clothing, and wearing gloves when handling body fluids.
-Do not mix or dilute radium-223 dichloride with other solutions.
-Dispose of any unused product or contaminated materials in accordance with local regulations on radioactive waste.
Intravenous Administration
-Use aseptic technique during preparation and administration, as well as appropriate precautions for radiopharmaceuticals.
-Visually inspect product for particulate matter and discoloration.
-Flush the line with isotonic saline before and after administration.
-Administer as a slow intravenous injection over 1 minute.
Radium-233 dichloride in combination with best supportive care (n = 600) has been compared to best supportive care alone (n = 301) in a randomized, double-blind, placebo-controlled trial of patients with castration-resistant prostate cancer with symptomatic bone metastases. During the trial, anemia (all grades, 93% vs. 88%; grade 3 or 4, 6% vs. 6%) and lymphocytopenia (all grades, 72% vs. 53%; grade 3 or 4, 20% vs. 7%) were among the most frequently reported adverse events, with anemia and thrombocytopenia as the most common hematologic reasons for treatment discontinuation, each at a rate of 2%. Additional hematologic adverse effects included leukopenia (all grades, 35% vs. 10%; grade 3 or 4, 3% vs. less than 1%), thrombocytopenia (all grades, 31% vs. 22%; grade 3 or 4, 3% vs. less than 1%), and neutropenia (all grades, 18% vs. 5%; grade 3 or 4, 2% vs. less than 1%). Of patients who received radium-223, grade 3 or 4 thrombocytopenia (4% vs. 1%) and neutropenia (3% vs. 1%) occurred more frequently in those who had received prior treatment with docetaxel compared to patients who were docetaxel naive. In the randomized trial, bone marrow failure or ongoing pancytopenia occurred in 2% of patients receiving radium-223 (grade 3 or 4, 1%) compared to 0% of patients treated with placebo, resulting in 2 deaths. Additionally, fatal vascular hemorrhage in association with myelosuppression occurred in 1% of patients treated with radium-223 and 0.3% of patients who received placebo. Bone marrow failure was ongoing at the time of death in 7 of 13 patients in the radium-223 arm. In a phase I study, neutrophil and platelet nadirs occurred 2 to 3 weeks after treatment, and most patients recovered 6 to 8 weeks after administration. A complete blood count, including white blood cell count with differential, platelet count, hemoglobin, and hematocrit should be performed prior to initiation of therapy with radium-223 and before each dose. Prior to the first dose of radium-223, the absolute neutrophil count (ANC) should be greater than or equal to 1.5 x 109/L, platelet count greater than or equal to 100 x 109/L, and hemoglobin greater than or equal to 10 g/dL; before each subsequent dose, the ANC should be greater than or equal to 1 x 109/L and platelet count greater than or equal to 50 x 109/L. Discontinue treatment if labs have not recovered within 6 to 8 weeks of the last dose or if patients experience life-threatening complications despite supportive care for bone marrow suppression.
Radium-233 dichloride in combination with best supportive care (n = 600) has been compared to best supportive care alone (n = 301) in a randomized, double-blind, placebo-controlled trial of patients with castration-resistant prostate cancer with symptomatic bone metastases. During the trial, reported gastrointestinal adverse events included nausea (all grades, 36% vs. 35%; grade 3 or 4, 2% vs. 2%), diarrhea (all grades, 25% vs. 15%; grade 3 or 4, 2% vs. 2%), and vomiting (all grades, 19% vs. 14%; grade 3 or 4, 2% vs. 2%). Dehydration occurred in 3% of patients in the radium-223 arm and 1% of patients who received placebo. Monitor patients' oral intake and fluid status to ensure prompt treatment of patients with dehydration or hypovolemia.
Radium-233 dichloride in combination with best supportive care (n = 600) has been compared to best supportive care alone (n = 301) in a randomized, double-blind, placebo-controlled trial of patients with castration-resistant prostate cancer with symptomatic bone metastases. During the trial, the incidence of peripheral edema for patients treated with radium-223 was 13% (grade 3 or 4, 2%) compared to 10% for patients who received placebo (grade 3 or 4, 1%).
Radium-233 dichloride in combination with best supportive care (n = 600) has been compared to best supportive care alone (n = 301) in a randomized, double-blind, placebo-controlled trial of patients with castration-resistant prostate cancer with symptomatic bone metastases. During the trial, the incidence of infectious-related complications were similar in patients treated with radium-223 and placebo: serious infections, 10%; infection-related deaths, 2%; and febrile neutropenia: less than 1%.
Radium-233 dichloride in combination with best supportive care (n = 600) has been compared to best supportive care alone (n = 301) in a randomized, double-blind, placebo-controlled trial of patients with castration-resistant prostate cancer with symptomatic bone metastases. During the trial, an injection site reaction (including erythema, pain, and edema) was reported in 1% of patients treated with radium-223.
Radium-233 dichloride in combination with best supportive care (n = 600) has been compared to best supportive care alone (n = 301) in a randomized, double-blind, placebo-controlled trial of patients with castration-resistant prostate cancer with symptomatic bone metastases. Radium-223 contributes to long-term cumulative radiation exposure, which is associated with an increased risk of new primary malignancy. Rats treated with radium-223 also experienced neoplastic changes, including osteosarcoma. During the trial, new primary malignancy was reported in less than 1% of patients treated with radium-223, compared to 2% of patients who received placebo; however, this may not be reflective of the true incidence due to the relatively short period of follow-up.
In a randomized, double blind, placebo controlled phase 3 trial, hematologic adverse effects occurred more frequently in patients treated with radium-223 dichloride than placebo, including bone marrow failure (with 2 associated deaths), ongoing anemia, neutropenia, and thrombocytopenia (pancytopenia), and vascular hemorrhage. Prior to the first dose of radium-223 dichloride, the absolute neutrophil count (ANC) should be greater than or equal to 1.5 x 109/L, platelet count greater than or equal to 100 x 109/L, and hemoglobin greater than or equal to 10 g/dL. Before each subsequent dose, the ANC should be greater than or equal to 1 x 109/L and platelet count greater than or equal to 50 x 109/L. Discontinue treatment if labs have not recovered within 6 to 8 weeks of the last dose or if patients experience life-threatening complications despite supportive care for bone marrow suppression. The safety and efficacy of administering radium-223 dichloride in combination with chemotherapy is unknown. Due to the risk of additive myelosuppression, combination therapy is not recommended.
The safety and efficacy of radium-223 dichloride have not been established in females. Pregnancy should be avoided by females of reproductive potential with partners receiving treatment with radium-223 dichloride and for at least 6 months after the last dose. Radium-223 dichloride can cause fetal harm when administered during pregnancy based on its mechanism of action. Women who are pregnant or who become pregnant while their male partner is receiving radium-223 dichloride should be apprised of the potential hazard to the fetus. Although there are no human or animal data the use of radium-223 dichloride in pregnancy, maternal use of radiopharmaceuticals can affect fetal development.
Radium-223 dichloride is primarily (95.3%) an alpha particle-emitter, with 3.6% beta-particle emission and 1.1% gamma-particle emission. Alpha-particles are unable to penetrate skin; therefore, the radiation exposure associated with handling of patient doses is expected to be low. Take appropriate precautions for handling and administering radiopharmaceuticals and minimize the time spent in areas of radiation. In the event of accidental exposure of the skin or eyes to radium-223 dichloride, flush the affected area immediately with water. If a spill occurs, 0.01 M ethylene-diamine-tetraacetic acid (EDTA) may be used to remove contamination.
The safety and efficacy of radium-223 dichloride in neonates, infants, children, and adolescents have not been established. In animal studies, single and repeat doses (20 to 80 kBq/kg, or 0.541 to 2.16 microcurie/kg) caused depletion of osteocytes, osteoblasts, and osteoclasts; fibro-osseous lesions; disruption of growth; and missing or irregular teeth.
Radium-223 dichloride is not indicated for use in women. According to the manufacturer, it is unknown whether radium-223 dichloride is excreted in human milk; however, there is potential for serious radiation-related adverse effects in nursing infants. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.
Counsel patients about the reproductive risk and contraception requirements during radium-223 treatment. Because radiopharmaceuticals can affect spermatogenesis, there is potential for male-mediated teratogenicity. Sexually active males should use condoms and female partners of reproductive potential should avoid pregnancy and use effective contraception during and for at least 6 months after treatment with radium-223 dichloride. Additionally, based on its mechanism of action radium-223 dichloride may cause male infertility.
For the treatment of castration-resistant prostate cancer, in patients with symptomatic bone metastases and no known visceral metastatic disease:
Intravenous dosage:
Adults: 55 Kilobecquerel (kBq) (equal to 1.49 microcurie) per kg of body weight by slow IV injection over 1 minute, every 4 weeks for 6 injections. The safety and efficacy beyond 6 injections has not been studied. When calculating the dose, a decay correction factor must be used to account for the physical decay of radium-223 after packaging (see below). Immediately before and after administration, measure the net patient dose in a radioisotope dose calibrator that has been calibrated with a National Institute of Standards and Technology (NIST) traceable radium-223 standard and corrected for decay using the date and time of calibration. After initial calibration, re-calibrate the dose calibrator at least yearly, and after any maintenance that could affect the dosimetry.
Volume to be administered (mL) = Body weight in kg x 55 kBq/kg
Decay factor x 1,100 kBq/mL
or
Volume to be administered (mL) = Body weight in kg x 1.49 microcurie/kg
Decay factor x 30 microcurie/mL
Number of days from reference date on vial (Decay factor)
-14 (2.296) 0 (0.982)
-13 (2.161) 1 (0.925)
-12 (2.034) 2 (0.87)
-11 (1.914) 3 (0.819)
-10 (1.802) 4 (0.771)
-9 (1.696) 5 (0.725)
-8 (1.596) 6 (0.683)
-7 (1.502) 7 (0.643)
-6 (1.414) 8 (0.605)
-5 (1.33) 9 (0.569)
-4 (1.252) 10 (0.536)
-3 (1.178) 11 (0.504)
-2 (1.109) 12 (0.475)
-1 (1.044) 13 (0.447)
14 (0.42)
Maximum Dosage Limits:
-Adults
55 kBq/kg (1.49 microcurie/kg).
-Geriatric
55 kBq/kg (1.49 microcurie/kg).
-Adolescents
Safety and efficacy have not been established.
-Children
Safety and efficacy have not been established.
-Infants
Safety and efficacy have not been established.
-Neonates
Safety and efficacy have not been established.
Patients with Hepatic Impairment Dosing
Since radium-223 dichloride is not metabolized in the liver and does not undergo biliary excretion, it does not appear that hepatic impairment should affect the pharmacokinetics. A dedicated trial in patients with hepatic impairment has not been conducted; however, based on a subgroup analysis in the randomized clinical trial, dose adjustment is not needed in patients with mild hepatic impairment. Insufficient data exists to make a recommendation in patients with moderate or severe hepatic impairment.
Patients with Renal Impairment Dosing
A dedicated trial in patients with renal impairment has not been conducted; however, based on a subgroup analysis in the randomized clinical trial, dose adjustment is not needed in patients with mild or moderate renal impairment (CrCL greater than or equal to 30 mL/min). Insufficient data exists to make a recommendation in patients with severe renal impairment (CrCL less than 30 mL/min).
*non-FDA-approved indication
Abiraterone: (Major) Radium RA 223 dichloride is not recommended for use in combination with abiraterone plus prednisone or prednisolone outside of clinical trials. The risk of fractures (28.6% vs. 11.4%) and death (38.5% vs. 35.5%) was increased with the use of Radium RA 223 dichloride compared with placebo, both in combination with abiraterone and prednisone/prednisolone, in a randomized phase 3 trial. The safety and efficacy of Radium RA 223 dichloride and agents other than gonadotropin-releasing hormone analogues have not been established.
Cholera Vaccine: (Moderate) Patients receiving immunosuppressant medications may have a diminished response to the live cholera vaccine. When feasible, administer indicated vaccines prior to initiating immunosuppressant medications. Counsel patients receiving immunosuppressant medications about the possibility of a diminished vaccine response and to continue to follow precautions to avoid exposure to cholera bacteria after receiving the vaccine.
Clozapine: (Major) It is unclear if concurrent use of other drugs known to cause neutropenia (e.g., antineoplastic agents) increases the risk or severity of clozapine-induced neutropenia. Because there is no strong rationale for avoiding clozapine in patients treated with these drugs, consider increased absolute neutrophil count (ANC) monitoring and consult the treating oncologist.
Dengue Tetravalent Vaccine, Live: (Moderate) Patients receiving immunosuppressant medications may have a diminished response to the dengue virus vaccine. When feasible, administer indicated vaccines at least 2 weeks prior to initiating immunosuppressant medications. If vaccine administration is necessary, consider revaccination following restoration of immune competence. Counsel patients receiving immunosuppressant medications about the possibility of a diminished vaccine response and to continue to follow precautions to avoid exposure after receiving the vaccine.
Niraparib; Abiraterone: (Major) Radium RA 223 dichloride is not recommended for use in combination with abiraterone plus prednisone or prednisolone outside of clinical trials. The risk of fractures (28.6% vs. 11.4%) and death (38.5% vs. 35.5%) was increased with the use of Radium RA 223 dichloride compared with placebo, both in combination with abiraterone and prednisone/prednisolone, in a randomized phase 3 trial. The safety and efficacy of Radium RA 223 dichloride and agents other than gonadotropin-releasing hormone analogues have not been established.
SARS-CoV-2 (COVID-19) vaccines: (Moderate) Patients receiving immunosuppressant medications may have a diminished response to the SARS-CoV-2 virus vaccine. When feasible, administer indicated vaccines prior to initiating immunosuppressant medications. Counsel patients receiving immunosuppressant medications about the possibility of a diminished vaccine response and to continue to follow precautions to avoid exposure to SARS-CoV-2 virus after receiving the vaccine.
SARS-CoV-2 Virus (COVID-19) Adenovirus Vector Vaccine: (Moderate) Patients receiving immunosuppressant medications may have a diminished response to the SARS-CoV-2 virus vaccine. When feasible, administer indicated vaccines prior to initiating immunosuppressant medications. Counsel patients receiving immunosuppressant medications about the possibility of a diminished vaccine response and to continue to follow precautions to avoid exposure to SARS-CoV-2 virus after receiving the vaccine.
SARS-CoV-2 Virus (COVID-19) mRNA Vaccine: (Moderate) Patients receiving immunosuppressant medications may have a diminished response to the SARS-CoV-2 virus vaccine. When feasible, administer indicated vaccines prior to initiating immunosuppressant medications. Counsel patients receiving immunosuppressant medications about the possibility of a diminished vaccine response and to continue to follow precautions to avoid exposure to SARS-CoV-2 virus after receiving the vaccine.
SARS-CoV-2 Virus (COVID-19) Recombinant Spike Protein Nanoparticle Vaccine: (Moderate) Patients receiving immunosuppressant medications may have a diminished response to the SARS-CoV-2 virus vaccine. When feasible, administer indicated vaccines prior to initiating immunosuppressant medications. Counsel patients receiving immunosuppressant medications about the possibility of a diminished vaccine response and to continue to follow precautions to avoid exposure to SARS-CoV-2 virus after receiving the vaccine.
Radium-223 dichloride is an alpha particle-emitting radiopharmaceutical administered via intravenous injection. When new bone formation occurs around bone metastases, radium-223 dichloride mimics calcium to form complexes with hydroxyapatite, a calcium-containing component of the bone matrix, at areas of increased bone turnover such as bone metastases. Once incorporated into the bone matrix, the high linear energy transfer of alpha particles (80 keV/micrometer) leads to a high frequency of double-strand DNA breaks in adjacent cells including tumor cells, osteoblasts, and osteoclasts, resulting in an anti-tumor effect on bone metastases. Alpha-particle emitters such as radium-223 dichloride have very short penetration of tissue (less than 100 micrometers, or 2 to 10 cell diameters), resulting in minimal damage to surrounding tissue.
-Route-Specific Pharmacokinetics
Intravenous Route
After intravenous administration, radium-223 exhibits linear pharmacokinetics and is rapidly cleared from the bloodstream and distributed primarily into bone or excreted into the intestine. Based on calculations from data in 5 patients with castration-resistant prostate cancer, radioactivity to bone approximates 4,262.6 rad/mCi, red marrow and upper and lower large intestine walls each absorb less than 515 rad/mCi of radiation, and other organs absorb less than 27 rad/mCi per dose. Fifteen minutes after administration, 20% of the injected radioactive dose remained in the blood; after 4 hours, 4% remained in the blood (61% in bone, no significant uptake in heart, liver, kidneys, urinary bladder, and spleen); after 24 hours, less than 1% remained in the blood.
Radium-223 dichloride is a radiopharmaceutical isotope that decays and is not metabolized. After correcting for decay, approximately 63% of the administered radioactivity was excreted from the body within 7 days of administration, with 13% (range, 0% to 34%) in fecal matter at 48 hours and 2% (range, 1% to 5%) in urine. The rate of elimination is influenced by intestinal transit rates; it is unknown whether patients with slower transit rates will receive higher intestinal radiation exposure and thus increased gastrointestinal toxicity. Radium-223 dichloride has a physical half-life of 11.4 days.
-Special Populations
Hepatic Impairment
Pharmacokinetic studies have not been conducted in patiens with hepatic impairment; however, radium-223 dichloride is not metabolized, nor is there evidence of hepato-biliary excretion based on imaging data. The presence of hepatic impairment is not expected to affect the pharmacokinetics of radium-223 dichloride.
Renal Impairment
Pharmacokinetic studies have not been conducted in patiens with renal impairment; however, radium-223 dichloride exhibits minimal renal clearance. The presence of renal impairment is not expected to affect the pharmacokinetics of radium-223 dichloride.
Pediatrics
The safety and efficacy of radium-223 dichloride have not been established in children and adolescents below age 18.