Prostate cancer is the most common cancer in men and the third leading cause of cancer-related deaths in Canadian men. Despite hormone and radiation therapies, most patients progress to late-stage metastatic castrate-resistant prostate cancer (mCRPC). 177Lu-PSMA617 radioligand therapy (rLT) is a radioactive biochemical substance that targets the human prostate-specific membrane antigen (hPSMA). This rLT has been used in compassionate trials in mCRPC patients and has been demonstrated significant clinical efficacy. However, recent findings suggest that this efficacy is short-lived, and most patients exhibit tumor recurrence [96]. Here we establish a murine model to study the anti-tumor effects and the corresponding immune response of 177Lu-PSMA617 rLT on prostate cancer. We generated a doxycycline-inducible hPSMA-expressing murine prostate cancer (hPSMA TRAMP-C2) cell line with high binding responses to PSMA617. Using this system, we evaluated the in vitro and in vivo binding of 177Lu-PSMA617 to the hPSMA TRAMP-C2 cell line. Here, we show that the hPSMA TRAMP-C2 cell line expresses hPSMA upon doxycycline induction and that 177Lu-PSMA617 can bind to its target in vitro and in vivo. Together, these results show that the developed hPSMA TRAMP-C2 cell line can be used to investigate therapeutic and immunological responses targeted against PSMA in prostate cancer. / Graduate

Introduction: Prostate-specific membrane antigen (PSMA)-based imaging and theranostics have played an important ole in the diagnosis, staging, and treatment of prostate cancer (PCa). We aimed to evaluate the acceptance and use of PSMA theranostics among German urologists.- Methods: An anonymous online questionnaire was sent via survio.com to the members of the German Society of Urology (DGU). - Results: Seventy-two percent of participants performed PSMA positron emission tomography (PET) imaging regularly in biochemically recurrent PCa. Overall, 61% of participants considered PSMA-radioligand therapy to be very useful or extremely useful. PSMA PET imaging in high-risk PCa is more often considered by urologists working in a university setting than in nonuniversity settings or medical practices (51% vs. 25%, p < 0.001). Most perform PSMA-radioligand therapy as an option after all approved systemic treatments for metastatic metastatic castration-resistant PCa (56%) or after cabazitaxel (14%). A total of 93.9% and 70.3% of respondents consider the lack of reimbursement by health insurance to be the main obstacle to using PSMA PET imaging or radioligand therapy, respectively. - Discussion/Conclusion: PSMA-based maging/theranostics are already widely applied but would find even more widespread use if reimbursement is clearly regulated by health insurance in Germany.