Abstract
T3
Introduction: To optimize the Pluvicto intravenous infusion, scintigraphic imaging, and patient-specific radiation safety instructions.
Pluvicto® (Lutetium-177 vipivotide textraxetran) is an FDA-approved therapeutic radiopharmaceutical for adult patients with prostate specific membrane antigen (PSMA) avidity for metastatic castration-resistant prostate cancer previously treated with androgen receptor blockers and taxane-based systemic therapy. Pluvicto consists of six 200mCi (7.4GBq) therapeutic cycles every six weeks unless the patient experiences any dose limiting toxicities. We discuss our optimized methods of administering, imaging, and providing post-treatment radiation safety precautions for patients receiving Pluvicto.
Methods: Prior to the Pluvicto infusion, each patient is hydrated with 250mL of sterile 0.9% sodium chloride intravenously while concomitantly receiving an anti-emetic intravenously for 20min. After the anti-emetic, Pluvicto can be administered via a syringe, the gravity method, or a peristaltic pump. We have tested all three methods and found the peristaltic pump allows for a safe continuous infusion of the radiopharmaceutical while adhering to the ALARA principal for personnel doses and being able to accurately identify the start and end of infusion using the dosage volume to be administered. Infusing the radiopharmaceutical directly from the vial eliminates the unnecessary radiation exposure to staff that would occur when transferring the radiopharmaceutical from the vial to a syringe, eliminates geometry effects when assaying the dose from a vial to a syringe, and reduces residual activity by eliminating additional materials used for the infusion.
Post-infusion anterior and posterior whole-body planar scintigraphic images are acquired followed by a SPECT/CT of the lower abdomen and pelvis to identify localized sites of PSMA-avid disease. The whole-body planar images are acquired at 10 cm/min, and SPECT/CT is acquired at 20 sec per step.
Post-Pluvicto, radiation safety instructions to the patient are generated from the following criteria: the net dose administered, the patient's living conditions, and a literature-based bi-exponential fit to the whole-body clearance curve. In-house software then calculates the dates and times until which patients should sleep alone and avoid pregnant women and children, and after which they may travel via mass transportation and return to work based on the US Nuclear Regulatory Commission Regulatory Guide 8.39. Although not currently required, our conservative practice is to divide the annual dose limits by six for each administration so that the combined therapeutic Pluvicto cycles remain below the dose limits.
Results: Utilizing the peristaltic pump for administering intravenous hydration, anti-emetic, and Pluvicto is a safe and reliable method of infusion. Post-treatment scintigraphic imaging and SPECT/CT demonstrates the radiopharmaceutical biodistribution, disease localization and identifies localized PSMA-avid disease in the pelvis for monitoring each therapeutic cycle. The patients' release instructions typically allow immediate traveling and call for sleeping alone for two nights and avoiding children and pregnant women in the household for one day.
Conclusions: It is practical to run a busy, yet safe Pluvicto practice by using a peristaltic pump to administer intravenous hydration, anti-emetic, and the radiopharmaceutical, monitoring the treatments with whole body planar scintigraphy and SPECT/CT, and basing the patients' release instructions on the administered activity and a bi-exponential whole body clearance model to stay below the annual dose limits over the course of all six cycles of treatment.
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