Abstract 1414P
Background
Lutetium-177 prostate-specific membrane antigen radioligand therapy (177Lu-PSMA-RLT) is an option for treatment of metastatic castration-resistant prostate cancer (mCRPC). It is increasingly used in old or comorbid patients. Purpose was to evaluate the safety and efficacy in patients ≥80 years of age.
Methods
Seventy-nine mCRPC patients who underwent 177-lutetium–labeled PSMA-I&T RLT at the age of 80 or older (median age 82, IQR:81-84) between March 2016 and September 2021 were selected from our institutional database. Patients were previously treated with androgen receptor-directed therapy and taxane-based chemotherapy or were chemotherapy-ineligible. All patients showed high PSMA-ligand uptake at PSMA-PET. Treatment was performed with a total of 344 cycles (median 4 cycles, range:1–12) and a median activity of 27.9 GBq (IQR:14.9-43.9) on a 4 to 6 weeks interval base. Toxicity data were acquired until 6 months after last treatment. Best PSA-response, progression-free survival (PFS) and overall survival (OS) were obtained.
Results
Median number of previous mCRPC treatment regimens was two, 50/79 (63.3%) patients were chemotherapy-naïve (CTx-naïve) before Lu-177-PSMA therapy, 14/79 (17.7%) patients had visceral metastases. A PSA decline of 90% was achieved in 25/79 (31.6%), a 50%-PSA decline in 38/79 (48.1%) patients. CTx-naïve patients showed higher PSA response rates compared to CTx-pretreated patients (55.1% vs. 44.0% 50%-PSA-decline). Median PFS and OS were 9.5 and 16.5 months. Median PFS and OS of CTx-naïve patients were significantly longer compared to CTx-pretreated patients (11.3 months vs. 6.4 months and 20.4 vs. 14.0 months, respectively, both p<0.01). Treatment related grade 3 toxicities were anemia in 4/79 (5%), thrombocytopenia in 3/79 (4%) and chronic renal impairment in 6/79 (8%) patients, no nonhematologic grade 3 and no grade 4 toxicities were observed. Most frequent clinical side effects were grade 1-2 xerostomia, fatigue and inappetence.
Conclusions
Response rates and toxicity of 177Lu-PSMA RLT in old mCRPC patients are comparable to published data. Chemotherapy-naïve patients showed a better and longer response to therapy than chemotherapy-pretreated patients.
Clinical trial identification
Legal entity responsible for the study
Klinikum Rechts der Isar, Technichal University Munich.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.