Predictors of response to radioligand therapy of metastatic castrate-resistant prostate cancer with 177Lu-PSMA-617

Radioligand therapy (RLT) with (177)Lu-PSMA-617 (Lu-PSMA-617) (prostate-specific membrane antigen) is a novel targeted therapy for metastatic prostate cancer. In this study, we evaluated the effect of different pre-therapeutic parameters on the therapeutic response measured by prostate-specific antigen(PSA) two months after RLT.

RLT was performed in 40 hormone and/or chemo refractory patients with distant metastases and progressive disease (mean age: 71.4 y/o). (68)Ga-PSMA-11 positron emission tomography/computed tomography(PET/CT) was performed in all patients one to two weeks prior to RLT. All patients were treated with a mean of 6 GBq. Standard-uptake-value(SUV)max of tumor lesions was determined using region of interest (ROI) analysis. Complete blood counts, renal and liver function assessments, previous therapies, pain medication and SUVs were included in the analysis. PSA was assessed two months after RLT.

In the univariate analysis, younger age, higher levels of GGT, lower pre-therapeutic hemoglobin, a higher Gleason score, a higher number of platelets, higher CRP, regular need for pain medication and higher LDH had a negative impact on the therapeutic response; however, the multivariate analysis revealed that the most significant independent factors were the number of platelets and regular need for pain medication. The response was independent of the amount of PSMA uptake as well as previous therapies, and other measured factors.

The response seems to be independent of the amount of pretherapeutic SUVmax of (68)Ga-PSMA-11 PET. A PSA-decline > 50 % was observed significantly more in patients with a Gleason score (<10) as well as in patients without a regular need for analgesics.

Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2016 Sep 01 [Epub ahead of print]

Justin Ferdinandus, Elisabeth Eppard, Florian Gärtner, Stefan Kürpig, Rolf Fimmers, Anna Yordanova, Stefan Hauser, Georg Feldmann, Markus Essler, Hojjat Ahmadzadehfar

University Hospital Bonn - Department of Nuclear Medicine, Germany;, Institute for Medical Biometry, Informatics and Epidemiology, University of Bonn, Germany;, University Hospital Bonn - 3. Department of Urology, Germany;, University Hospital Bonn - Department of Oncology, Germany.