Response prediction to 7400MBq ¹⁷⁷ Lu-PSMA-617 at 4 weeks interval in patients with metastatic castration resistance prostate cancer

Ziel/Aim We sought factors predict response to [¹⁷⁷Lu]Lu-PSMA-617 radio-ligand therapy (PSMA-RLT) in a homogenous cohort of patients received 7400MBq every 4 week.

Methodik/Methods Data of 61 patients (mean age 72 ± 6 years, median PSA prior the therapy begin 68.6 [range 1.0–4890 μg/L]), pretreated with Abiraterone/Enzalutamide (70  %) and Docetaxel/Cabazitaxel (69  %), all received three PSMA-RLT cycles (mean 7321 ± 592MBq) at four weekly intervals, were analyzed retrospectively. General-medical conditions and laboratory parameters of every patients were regularly assessed. Response to therapy was based on PSA levels one month after the 3rd cycle. Cox proportional hazard model was performed to detect response predictors and Kaplan-Meier estimates were used to evaluate overall survival (OS).

Ergebnisse/Results Collectively, 49 patients (80.3  %) demonstrated a therapy response in terms of any PSA decline, while 21 patients (19.7  %) showed increase or no changes in PSA levels. Although factors like initial levels of hemoglobin (Hb), lactate dehydrogenase, and alkaline phosphatase and initial Eastern Cooperative Oncology Group (ECOG) status could significantly predict therapy response (Prd cycle, patients with initial Hb levels within normal range showed also a significantly higher OS than patients with subnormal Hb levels (89 weeks (95  %CI 64.6–113.0), vs. median survival not reached, P = 0.016). Neither pretreatments with Abiraterone/Enzalutamide or Docetaxel/Cabazitaxel nor localization and numbers of metastasis affected rate of response.

Schlussfolgerungen/Conclusions Initial Hb levels prior the therapy begin was an independent predictor for therapy response in patients received an intense PSMA-RLT every four weeks. Both PSA decline 4 weeks after the 3^rd cycle and normal Hb levels prior the 1^st cycle predicted longer survival.