A Primer on Radiopharmaceutical Therapy

Abstract

The goal of this article is to serve as a primer for the United States-based radiation oncologist who may be interested in learning more about radiopharmaceutical therapy (RPT). Specifically, we define RPT, review the data behind its current and anticipated indications, and discuss important regulatory considerations for incorporating it into clinical practice. RPT represents an opportunity for radiation oncologists to leverage 2 key areas of expertise, namely therapeutic radiation therapy and oncology, and apply them in a distinct context in collaboration with nuclear medicine and medical oncology colleagues. Although not every radiation oncologist will incorporate RPT into their day-to-day practice, it is important to understand the role for this modality and how it can be appropriately used in select patients.

Figure 1

Properties of radiation emissions used for radiopharmaceutical therapy.

Figure 2

Generalized structure of a tumor or tumor-microenvironment-selective radiopharmaceutical therapeutic agent

Figure 3

FDA-approved radiopharmaceutical therapy agents. * denotes agents no longer commercially available.

Figure 4

Different disease burden. Same treatment course. Generalized illustration of the concept of personalized dosimetry. Two patients with prostate adenocarcinoma imaged with ¹⁸F-DCFPyL who have different disease burdens. Per FDA label of ¹⁷⁷Lu-PSMA-617 (Pluvicto^™), both would receive the same weight-based injected activity 7.4 GBq per cycle. Given the difference in disease between the two patients, the normal organ absorbed doses could potentially be much higher than expected in the patient on the left, while tumors may be underdosed in the patient on the right.