Ga Drug Information

Generic name: GALLIUM GA-68 GOZETOTIDE

Radioactive Diagnostic Agent [EPC]

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Uses of Ga

Gallium Ga 68 gozeotide injection is indicated for positron emission tomography (PET) of prostate-specific membrane antigen (PSMA) positive lesions in men with prostate cancer: with suspected metastasis who are candidates for initial definitive therapy. with suspected recurrence based on elevated serum prostate-specific antigen (PSA) level.

Dosage & Administration of Ga

Radiation Safety – Drug Handling Handle Gallium Ga 68 gozetotide injection with appropriate safety measures to minimize radiation exposure. Use waterproof gloves, effective radiation shielding, and other appropriate safety measures when preparing and handling Gallium Ga 68 gozetotide injection. Radiopharmaceuticals should be used by or under the control of physicians who are qualified by specific training and experience in the safe use and handling of radionuclides, and whose experience and training have been approved by the appropriate governmental agency authorized to license the use of radionuclides.

Recommended Dosage and Administration Instructions Recommended Dosage In adults, the recommended amount of radioactivity to be administered for PET is 111 MBq to 259 MBq (3 mCi to 7 mCi) administered as an intravenous bolus injection. Administration Use aseptic technique and radiation shielding when withdrawing and administering Gallium Ga 68 gozetotide injection. Calculate the necessary volume to administer based on calibration time and required dose.

Inspect Gallium Ga 68 gozetotide injection visually for particulate matter and discoloration before administration. Do not use the drug if the solution contains particulate matter or is discolored. Gallium Ga 68 gozetotide injection may be diluted with sterile 0.9% Sodium chloride injection, USP.

Assay the final dose immediately before administration to the patient in a dose calibrator. After injection of Gallium Ga 68 gozeotide injection, administer an intravenous flush of sterile 0.9% Sodium chloride injection, USP to ensure full delivery of the dose. Dispose of any unused drug in a safe manner in compliance with applicable regulations.

Unless contraindicated, a diuretic expected to act within the uptake time period may be administered at the time of radiotracer injection to potentially decrease artifact from radiotracer accumulation in the urinary bladder and ureters.

Patient Preparation Prior to PET Imaging

Instruct patients to drink a sufficient amount of water to ensure adequate hydration prior to administration of Gallium Ga 68 gozeotide injection and to continue to drink and void frequently following administration to reduce radiation exposure, particularly during the first hour after administration.

Image Acquisition Position the patient supine with arms above the head. Begin PET scanning 50 to 100 minutes after the intravenous administration of Gallium Ga 68 gozetotide injection. Patients should void immediately prior to image acquisition and that image acquisition should begin at the proximal thighs and proceed cranially to the skull base or skull vertex.

Adapt imaging technique according to the equipment used and patient characteristics in order to obtain the best image quality possible.

Image Interpretation Gallium Ga 68 gozetotide binds to prostate-specific membrane antigen (PSMA). Based on the intensity of the signals, PET images obtained using Gallium Ga 68 gozetotide injection indicate the presence of PSMA in tissues. Lesions should be considered suspicious if uptake is greater than physiologic uptake in that tissue or greater than adjacent background if no physiologic uptake is expected.

Tumors that do not bear PSMA will not be visualized. Increased uptake in tumors is not specific for prostate cancer.

Radiation Dosimetry

Estimated radiation absorbed doses per injected activity for organs and tissues of adult male patients following an intravenous bolus of Gallium Ga 68 gozetotide injection are shown in Table 1. The effective radiation dose resulting from the administration of 259 MBq (7 mCi) is about 4.4 mSv. The radiation doses for this administered dose to the critical organs, which are the kidneys, urinary bladder, and spleen, are 96.2 mGy, 25.4 mGy, and 16.8 mGy, respectively.

These radiation doses are for Gallium Ga 68 gozetotide injection alone. If CT or a transmission source are used for attenuation correction, the radiation dose will increase by an amount that varies by technique. Table 1: Estimated Radiation Absorbed Dose per Injected Activity in Selected Organs and Tissues of Adults after Intravenous Administration of Gallium Ga 68 gozetotide injection

Table 1: Estimated Radiation Absorbed Dose per Injected Activity in Selected Organs and Tissues of Adults after Intravenous Administration of Gallium Ga 68 gozetotide injection
OrganAbsorbed dose (mGy/MBq)
MeanSD
Adrenals0.01560.0014
Brain0.01040.0011
Breasts0.01030.0011
Gallbladder0.01570.0012
Lower Colon0.01340.0009
Small Intestine0.01400.0020
Stomach0.01290.0008
Heart0.01200.0009
Kidneys0.37140.0922
Liver0.04090.0076
Lungs0.01110.0007
Muscle0.01030.0003
Pancreas0.01470.0009
Red Marrow0.01140.0016
Skin0.00910.0003
Spleen0.06500.0180
Testes0.01110.0006
Thymus0.01050.0006
Thyroid0.01040.0006
Urinary Bladder0.09820.0286
Total Body0.01430.0013
Effective Dose (mSv/MBq)0.01690.0015

Side Effects of Ga

The most commonly reported adverse reactions include nausea, diarrhea, and dizziness. To report SUSPECTED ADVERSE REACTIONS, contact Ionetix at 1-517-252-4069 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The safety of Gallium Ga 68 gozetotide injection was evaluated in 960 patients, each receiving one dose of Gallium Ga 68 gozetotide injection. The average injected activity was mCi.

Warnings & Cautions for Ga

Risk for Misdiagnosis

Image interpretation errors can occur with gallium Ga 68 gozetotide PET. A negative image does not rule out the presence of prostate cancer and a positive image does not confirm the presence of prostate cancer. The performance of Gallium Ga 68 gozetotide injection for imaging of biochemically recurrent prostate cancer seems to be affected by serum PSA levels and by site of disease.

The performance of Gallium Ga 68 gozetotide injection for imaging of metastatic pelvic lymph nodes prior to initial definitive therapy seems to be affected by Gleason score. Gallium Ga 68 gozetotide uptake is not specific for prostate cancer and may occur with other types of cancer as well as non-malignant processes such as Paget's disease, fibrous dysplasia, and osteophytosis. Clinical correlation, which may include histopathological evaluation of the suspected prostate cancer site, is recommended.

Radiation Risks Gallium Ga 68 gozetotide injection contributes to a patient's overall long-term cumulative radiation exposure. Long-term cumulative radiation exposure is associated with an increased risk for cancer. Ensure safe handling to minimize radiation exposure to the patient and health care workers.

Advise patients to hydrate before and after administration and to void frequently after administration.

Drug Interactions with Ga

Androgen deprivation therapy and other therapies targeting the androgen pathway Androgen deprivation therapy (ADT) and other therapies targeting the androgen pathway, such as androgen receptor antagonists, can result in changes in uptake of gallium Ga 68 gozetotide in prostate cancer. The effect of these therapies on performance of gallium Ga 68 gozetotide PET has not been established.

Pregnancy Safety for Ga

Pregnancy Risk Summary Gallium Ga 68 gozetotide injection is not indicated for use in females. There are no available data with Gallium Ga 68 gozetotide injection use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes. All radiopharmaceuticals, including Gallium Ga 68 gozetotide injection, have the potential to cause fetal harm depending on the fetal stage of development and the magnitude of the radiation dose.

Animal reproduction studies have not been conducted with gallium Ga 68 gozetotide injection.

Pediatric Use of Ga

Pediatric Use The safety and effectiveness of Gallium Ga 68 gozetotide injection have not been estabished in pediatric patients.

Overdosage Information for Ga

In the event of an overdose of gallium Ga 68 gozetotide injection, reduce the radiation absorbed dose to the patient where possible by increasing the elimination of the drug from the body using hydration and frequent bladder voiding. A diuretic might also be considered. If possible, an estimate of the radiation effective dose given to the patient should be made.

Clinical Studies of Ga

The safety and efficacy of Gallium Ga 68 gozetotide injection were established in two prospective, open-label studies, PSMA-PreRP ( NCT03 7 ), in men with prostate cancer. PSMA-PreRP This two-center study enrolled 325 patients with biopsy-proven prostate cancer who were considered candidates for prostatectomy and pelvic lymph node dissection. All enrolled patients met at least one of the following criteria: serum prostate-specific antigen (PSA) of at least 10 ng/mL, tumor stage cT2b or greater, or Gleason score greater than 6.

Each patient received a single gallium Ga 68 gozetotide PET/CT or PET/MR from mid-thigh to skull base. A total of 123 patients (38%) proceeded to standard-of-care prostatectomy and template pelvic lymph node dissection and had sufficient histopathology data for evaluation (evaluable patients). Three members of a pool of six central readers independently interpreted each PET scan for the presence of abnormal gallium Ga 68 gozetotide uptake in pelvic lymph nodes located in the common iliac, external iliac, internal iliac, and obturator subregions bilaterally as well as in any other pelvic location.

The readers were blinded to all clinical information except for the history of prostate cancer prior to definitive treatment. Extrapelvic sites and the prostate gland itself were not analyzed in this study. For each patient, gallium Ga 68 gozetotide PET results and reference standard histopathology obtained from dissected pelvic lymph nodes were compared by region (left hemipelvis, right hemipelvis, and other).

The median serum PSA was 11.8 ng/mL. The summed Gleason score was of the patients, with the remainder of the patients having Gleason scores of 6 or 10. Table 5 compares majority PET reads to pelvic lymph node histopathology results at the patient-level with region matching, such that at least one true positive region defines a true positive patient.

In an exploratory subgroup analysis based on summed Gleason score, there was a numerical trend toward more true positives in patients with Gleason score of 8 or higher compared to those with Gleason score of 7 or lower. An exploratory analysis was performed to estimate the sensitivity and specificity for pelvic nodal metastasis detection in all scanned patients, including the patients who were lacking histopathology reference standard. An imputation method was used based on patient-specific factors.

PSMA-BCR This two-center study enrolled 635 patients with biochemical evidence of recurrent prostate cancer after definitive therapy, defined by serum PSA of >0.2 ng/mL more than 6 weeks after prostatectomy or by an increase in serum PSA of at least 2 ng/mL above nadir after definitive radiotherapy. Three members of a pool of nine independent central readers evaluated each scan for the presence and regional location (20 subregions grouped into four regions) of abnormal gallium Ga 68 gozetotide uptake suggestive of recurrent prostate cancer. The readers were blinded to all clinical information other than type of primary therapy and most recent serum PSA level.

A total of 469 patients (74%) had at least one positive region detected by gallium Ga 68 gozetotide PET majority read. Two hundred and ten patients had composite reference standard information collected in a PET positive region (evaluable patients), consisting of at least one of the following: histopathology, imaging (bone scintigraphy, CT, or MRI) acquired at baseline or within 12 months after gallium Ga 68 gozetotide PET, or serial serum PSA. Composite reference standard information for gallium Ga 68 gozetotide PET negative regions was not systematically collected in this study.

White patients made up 90% of the group. The median serum PSA was 3.6 ng/mL. Prior treatment included radical prostatectomy in 64% and radiotherapy in 73%.

Among the pool of nine readers used in the study, the proportion of patients who were true positive in one or more regions ranged from 82% to 97%. The prostate bed had the lowest proportion of true positive results at the region-level (76% versus 96% for non-prostate regions). An exploratory analysis was also performed in which gallium Ga 68 gozetotide PET positive patients who lacked reference standard information were imputed using an estimated likelihood that at least one location-matched PET positive lesion was reference standard positive based on patient-specific factors.

In another exploratory analysis using the same imputation approach for PET positive patients who lacked reference standard information, 340 of 635 patients (54%) were correctly detected as true positive (95% confidence interval: 50%, 57%) among all BCR patients who received a PET scan, whether it was read as positive or negative. The likelihood of identifying a gallium Ga 68 gozetotide PET positive lesion in this study generally increased with higher serum PSA level. Table 6 shows the patient-level gallium Ga 68 gozetotide PET results stratified by serum PSA level.

The mean time between PSA measurement and PET scan was 40 days with a range of 0 to 367 days. Percent PET positivity was calculated as the proportion of patients with a positive gallium Ga 68 gozetotide PET out of all patients scanned. Percent PET positivity includes patients determined to be either true positive or false positive as well as those in whom such determination was not made due to the absence of composite reference standard data.

Table 5: Patient-Level Performance of Gallium Ga 68 Gozetotide PET for Detection of Pelvic Lymph Node Metastasis with region matching where at least one true positive region defines a true positive patient in the PSMA-PreRP Study (n=123)
HistopathologyPredictive value (95% CI) PPV: positive predictive value, NPV: negative predictive value
PositiveNegative
PET scanPositive149PPV 61% (41%, 81%)
Negative1684NPV 84% (79%, 91%)
Total3093
Diagnostic performance (95% CI)Sensitivity 47% (29%, 65%)Specificity 90% (84%, 96%)
Table 6: Patient-Level gallium Ga 68 gozetotide PET Results and Percent PET Positivity Stratified by Serum PSA Level in the PSMA-BCR Study (n=628) 7 patients were excluded from this table due to protocol deviations
PSA (ng/mL)PET positive patientsPET negative patientsPercent PET positivity (95% CI) Percent PET positivity = PET positive patients/total patients scanned
TotalTP TP: true positive, FP: false positiveFPWithout reference standard
With reference standard
<0.548111368736%
12(27%, 44%)
≥0.5 and <144153263556%
18(45%, 67%)
≥1 and <271291411583%
30(75%, 91%)
≥2299137131492991%
150(88%, 94%)
Total4621921825216674%
210(70%, 77%)

Drug information sourced from the FDA. This content is for informational purposes only and does not constitute medical advice. Consult a healthcare professional before making any medication decisions.

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