Performance Analysis of PSMA Targeted Radioligand Therapy and different therapy intervals

Ziel/Aim:

Radioligand Therapy (RLT) using ¹⁷⁷Lu-PSMA-617 is generally well tolerated and shows respectable PSA response rates and seems to prolong survival. Initially a dose of 6 GBq ¹⁷⁷Lu-PSMA-617 per cycle at an 8 weekly interval was recommended. The aim of this study was to further evaluate response and safety of a 6 weekly interval combined with slightly elevated therapeutic activity.

Methodik/Methods:

A total number of 88 patients with mCRPC were included in this analysis. 42 patients were treated with a mean injected activity of 7.3 GBq ¹⁷⁷Lu-PSMA-617 (range 5,9 – 8,2 GBq) every 6 weeks and 46 patients were treated with a mean injected activity of 6,1 GBq (range 3,0 – 7,5 GBq) every 8 weeks, respectively. All patients had exhausted conventional therapeutic options. Only those patients who had received at least two lines of therapy (Chemotherapy and Abiraterone or Enzalutamide) were included. Data were analyzed with respect to response and safety according PCWG3 and CTCAE.

Ergebnisse/Results:

In 28 (6-weekly) and 19 patients (8-weekly) at least 4 cycles of RLT were performed. A PSA decline of 50% or more occurred in 62% (n = 26) under 6-weekly therapy and only 41% (n = 19) under 8-weekly therapyinterval. A moderate PSA decline of at least 30% and more occurred in 76% (n = 32) under 6-weekly therapy and 54% (n = 25) under 8-weekly therapy inteval. The estimated median overall survival in the 6-weekly cohort was not reached. In terms of CTCAE occurred no higher toxicity rates. According xerostomia no significant differences were reported.

Schlussfolgerungen/Conclusions:

Results from 88 patients show that shorter therapy intervals combined with slightly elevated doses is effective with respect to relevant PSA decline. Regarding Adverse Events toxicity is not elevated.