In this poster, Dr. Tagawa and colleagues present results from a phase 1/2 cohort (NCT03042468) of 44 men with mCRPC that had progressed after chemotherapy and either enzalutamide or abiraterone. A subset of the analyzed patients were part of the dose-escalation group, and the rest received the phase 2 radiation dose. There was no selection for PSMA expression prior to cohort inclusion and 177Lu-PSMA-617 treatment. PSMA-PET scans, standard staging imaging, and circulating tumor cell (CTC) counts were obtained before and after treatment. Treatment was administered in a hypofractionated dose of 1 cycle, 2 doses two weeks apart.
The median age of treated men was 59 (range 55-91), and the median PSA was 182.97 (range 0.9-5541). Almost all men had bone metastatic disease, 18% had lung mets, 9% had liver mets, and 9% had other visceral metastatic disease. In total, 82% of patients exhibited some PSA decline and 67% of patients receiving the phase 2 dose had a PSA decline of greater than 50%. At the time of data analysis, the median overall survival was 16 months, and 57.7% of patients with pre- and post-treatment data had a decrease in CTC count. Major side effects were xerostomia (61.4%) reflective of PSMA positivity in salivary glands, fatigue (29.5%), pain flare (25%) and nausea (15.5%). In a multivariate analysis incorporating dose of lutetium, PSMA PET SUVmax, prior chemotherapy, and other factors, the dose administered and maximum PSMA-PET SUV were associated with response to treatment.
Overall, this poster shows that a single fractionate cycle of 177Lu-PSMA-617 is safe and effectively lowers PSA in the majority of patients even without pre-selection for PSMA positivity in tumors. Pre-treatment PSMA PET may still prove to be important in choosing patients most likely to respond to therapy.
Presented by: Scott Tagawa, MD, Medical Oncologist and Medical Director of Genitourinary Oncology research at Weill Cornell Medical Center, New York, New York
Written by: Alok Tewari, MD, PhD, Medical Oncology Fellow at the Dana-Farber Cancer Institute, at the 2019 European Society for Medical Oncology annual meeting, ESMO 2019 #ESMO19, 27 Sept - 1 Oct 2019 in Barcelona, Spain
Overall, this poster shows that a single fractionate cycle of 177Lu-PSMA-617 is safe and effectively lowers PSA in the majority of patients even without pre-selection for PSMA positivity in tumors. Pre-treatment PSMA PET may still prove to be important in choosing patients most likely to respond to therapy.
Presented by: Scott Tagawa, MD, Medical Oncologist and Medical Director of Genitourinary Oncology research at Weill Cornell Medical Center, New York, New York