Combined selective internal radiation therapy and 177Lu-PSMA-617 in patients with mCRPC and progressive liver metastases

Ziel/Aim:

Prostate cancer is the most frequently occurring malignancy in men. Especially in case of metastatic castration resistant prostate cancer (mCRPC), liver metastases are associated with worse overall survival and there are limited options for their treatment. In the following, preliminary results demonstrate the efficacy of combining systemically administered radioligand therapy (¹⁷⁷Lu-PSMA-617) with locally administered selective internal radiation therapy (⁹⁰Y-SIRT) in patients with mCRPC and liver metastases.

Methodik/Methods:

Six mCRPC patients (median age: 73y) were pre-treated with androgen withdrawal and at least one second-generation antiandrogen (Enzalutamide or Abiraterone). All patients had liver metastases and were evaluated for ⁹⁰Y-SIRT (median injected dose: 2.2 GBq) subsequent to (n = 5) or followed by (n = 1) systemic treatment with ¹⁷⁷Lu-PSMA-617 (median injected dose: 6 GBq).

Ergebnisse/Results:

All patients were evaluated for SIRT, however due to rapid tumour progression therapy was not feasible for two patients. All patients had multiple osseous metastases, five showed lymphatic metastases. SIRT achieved a size reduction of hepatic metastases in all patients, yet lymph node and bone metastases burden were progressive. In patients pre-treated with ¹⁷⁷Lu-PSMA-617, PSA levels were increasing due to increased overall tumour burden post SIRT (median post/pre PSA ratio: 1.3).

Schlussfolgerungen/Conclusions:

The combination of selective internal radiation therapy and ¹⁷⁷Lu-PSMA-617 therapy is an efficient option for patients with mCRPC and liver metastases. Due to worse overall survival of patients with mCRPC and liver metastases, early therapy evaluation is recommended. ¹⁷⁷Lu-PSMA-617 alone seems insufficient for the treatment of liver metastases.