The FDA recently approved two new radiotracers for use in prostate cancer. Gallium (Ga)-68 prostate-specific membrane antigen (PSMA) was the first, approved in December of 2020. PSMA is a protein unique to prostate tissue which is found in high concentration in prostate cancer cells. Several studies have shown higher detection rates using Ga-68 PSMA when compared with radiotracers currently in use, specifically for detection of recurrence following radical prostatectomy. The second is piflufolastat F-18 (Pylarify), approved in May of 2021. It is similar to (Ga)-68 in both its affinity for PSMA, and its indications for use. While the evidence is promising, the NCCN cautions against overuse of PET/CT in prostate cancer, noting a high rate of false-positive studies and a lack of evidence linking earlier detection rates to improved outcomes .^[1]NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Prostate Cancer (Version 2.2021). Available at http://www.nccn.org. ©National Comprehensive Cancer Network, 2021.
The affinity of PSMA for prostate tissue makes it an attractive target for therapeutics as well. By linking PSMA with 177Lu, researchers have created a form of targeted radiation therapy (177Lu-PSMA) which has shown promise in treating castration-resistant prostate cancer. At the annual ASCO meeting, preliminary results of the VISION trial were reported, in which patients with metastatic, castration-resistant prostate cancer were randomized to treatment with 177Lu-PSMA plus standard therapy versus standard therapy alone . ^[2]Sartor AO, Morris MJ, Messman R, et al.  VISION: an international, prospective, open-label, multicenter, randomized phase III study of 177Lu-PSMA-617 in the treatment of patients with progressive … Continue reading Addition of 177Lu-PSMA reduced the risk of death by 40% and led to a 5.3 month improvement in overall survival. Additional studies are ongoing and FDA approval is expected later this year.
The “theragnostic” use of radiotracers is an emerging trend at the intersection of diagnostic imaging and therapeutics, and provides a unique opportunity for collaboration across Carelon’s Radiology and Radiation Oncology solutions. The guideline development team at Carelon will be working to keep clients and providers informed as new opportunities arise in this rapidly growing area.