In late June, a research team presented promising data about interim screening for metastatic prostate cancer patients at this year’s Annual Meeting of the Society of Nuclear Medicine and Molecular Imaging (SNMMI). ScienceDaily reported that the phase II trial was conducted in men who had metastatic castration-resistant prostate cancer and had undergone two cycles of a type of prostate-specific membrane antigen (PSMA) radioligand therapy known as lutetium-177 (177Lu); the men received a round of interim PSMA PET imaging. Researchers were able to deduce a significant predictive value for patient survival based off the PET scans, which helped them guide treatment for their patients.
The National Cancer Institute lists the five-year survival rate of men with metastatic prostate cancer as 30.5 percent; in order to provide the best care possible, physicians should be able to assess how successful a treatment is early on.
Patients who receive the 177Lu-PSMA therapy generally receive a preliminary PSMA PET scan to see whether or not they’re eligible for the treatment in the first place. In the past, interim PET scans have been shown to generate high predictive values for patients with lymphoma. This concept, however, hasn’t before been applied prostate cancer patients who are receiving 177Lu-PSMA therapy.
For this study, which was conducted at the Klinikum rechts der Isar hospital in Munich, Germany, the research team used software that was developed in-house–called qPSMA–to assess the tumor burden on patients’ bodies. This was a departure from measuring standardized uptake value, which is what is usually analyzed in situations like these.
Andrei Gafita, one of the study’s lead authors, stated that the team “found that tumor response assessed on interim PSMA PET after two RLT cycles was associated with overall survival.” He continued: “Our results therefore show that interim PSMA PET can be used for therapeutic response assessment in patients undergoing 177Lu-PSMA RLT. Furthermore, occurrence of new lesions in PSMA PET is a prognostic factor for disease progression and could be included in defining tumor response based on PSMA PET imaging.”
Gafita and his team believe that though they need to conduct additional analyses with more clinical parameters based off their work, this study is a trailblazer in the use of interim PSMA PET scans during 177Lu-PSMA radioligand therapy. Perhaps similar techniques can be employed with other manifestations of cancer and their treatment as well.