Top Line: What is the effect of Lu177-PSMA therapy prior to radical prostatectomy for high risk disease?
The Study: In this phase 1/2 study, patients with high risk prostate cancer who were planned to have radical prostatectomy were administered Lu177-PSMA prior to surgery. To be eligible, they had to have high uptake in the primary tumor on PSMA PET defined as a SUVmax of 20 or more. The rationale for this is that high PSMA expression should result in a higher Lu177-PSMA dose. A total of 20 patients received either 1 cycle (50%) or 2 cycles of Lu177-PSMA at a dose of 5 GBq. Node positive disease was present in 30% of patients. Surgery was performed 6 weeks after the last cycle. Serial whole body SPECT/CT and whole body activity measurement was performed after each treatment. The median highest absorbed dose across all lesions after the first cycle was 35.5 Gy. The median highest absorbed dose to the prostate was 19.9 Gy. Higher absorbed dose was observed after the first cycle compared to the second. Five of 20 patients had absorbed dose in the lymph nodes ranging from 20 Gy to 77 Gy. The majority (95%) received at least 10 Gy to gross disease, which is estimated to be a lower threshold for response. PSMA PET just prior to surgery showed a partial response in 55%. Most (80%) showed evidence of treatment effect on final pathology, however no patients had a pathologic complete response. Toxicity was low with no major surgical complications.
TBL: The LuTectomy study shows that preoperative Lu177-PSMA delivers targeted doses of radiation to the primary tumor and prostate for men with high risk disease undergoing radical prostatectomy. | Eapen, Eur Urol 2023
The Study: In this phase 1/2 study, patients with high risk prostate cancer who were planned to have radical prostatectomy were administered Lu177-PSMA prior to surgery. To be eligible, they had to have high uptake in the primary tumor on PSMA PET defined as a SUVmax of 20 or more. The rationale for this is that high PSMA expression should result in a higher Lu177-PSMA dose. A total of 20 patients received either 1 cycle (50%) or 2 cycles of Lu177-PSMA at a dose of 5 GBq. Node positive disease was present in 30% of patients. Surgery was performed 6 weeks after the last cycle. Serial whole body SPECT/CT and whole body activity measurement was performed after each treatment. The median highest absorbed dose across all lesions after the first cycle was 35.5 Gy. The median highest absorbed dose to the prostate was 19.9 Gy. Higher absorbed dose was observed after the first cycle compared to the second. Five of 20 patients had absorbed dose in the lymph nodes ranging from 20 Gy to 77 Gy. The majority (95%) received at least 10 Gy to gross disease, which is estimated to be a lower threshold for response. PSMA PET just prior to surgery showed a partial response in 55%. Most (80%) showed evidence of treatment effect on final pathology, however no patients had a pathologic complete response. Toxicity was low with no major surgical complications.
TBL: The LuTectomy study shows that preoperative Lu177-PSMA delivers targeted doses of radiation to the primary tumor and prostate for men with high risk disease undergoing radical prostatectomy. | Eapen, Eur Urol 2023