STUDY OF PREDICTIVE FACTORS FOR RESPONSE TO 177 LU-PSMA IN PATIENTS WITH METASTATIC CASTRATION-RESISTANT PROSTATE CANCER

Hugo Peslier ^1* Valérie Seegers ² Pierre-Alban Dufour ¹

• ¹ Department of Nuclear Medicine, Institut de Cancérologie de l'Ouest (ICO), Angers, France
• ² Research and Statistics Department, Institut de Cancérologie de l'Ouest (ICO), Angers, France

Introduction: Metastatic castration-resistant prostate cancer (mCRPC) is an aggressive disease with a poor prognosis and few therapeutic options. In recent years, 177Lu-PSMA, a novel radioligand therapy, has shown promising results in patients who have failed conventional therapies. However, around 30% of patients do not respond adequately to this treatment. In this retrospective cohort study, we examined clinical, biological, and 68Ga-PSMA PET/CT-derived factors associated with poor treatment response.Materials and Methods:We conducted a retrospective cohort study including 63 patients treated at ICO Angers for progressive mCRPC following Novel Hormonal Agents and taxane-based chemotherapy. The primary endpoint was early treatment discontinuation, defined as stopping therapy at or before the 4 th cycle. Secondary endpoints included PSA response and overall survival.Results: A total of 63 patients were included in the study. Factors associated with early treatment discontinuation included a BMI < 25 kg/m², PSA doubling time < 2 months, hemoglobin levels < 10 g/dL, albumin levels < 35 g/L, lactate dehydrogenase (LDH) levels > 250 IU/L and alkaline phosphatase (ALP) levels > 125 IU/L. On 68Ga-PSMA PET/CT imaging, low SULmax, high Total Tumor Volume, and a low PSG score were also linked to early treatment discontinuation.Conclusion:This study identified several clinical, biological, and 68Ga-PSMA PET/CT-derived factors associated with early treatment discontinuation. Patients with poor overall health, aggressive or extensive disease, or low PSMA expression are at higher risk of treatment failure.