Erdogan Mehmet, Sengul Sevim S, Cetin Bulent, Avcı Mustafa, Yagci Samet, Ozkoç Ismail, Barikan Damla Ezgi, Yildiz Mustafa
Department of Nuclear Medicine, Suleyman Demirel University Faculty of Medicine, Isparta, 32260, Turkey.
Division of Medical Oncology, Department of Internal Medicine, Suleyman Demirel University Faculty of Medicine, Isparta, Turkey.
Ann Nucl Med. 2022 Jun;36(6):562-569. doi: 10.1007/s12149-022-01739-3. Epub 2022 Apr 9.
Lutetium-177 (Lu) prostate-specific membrane antigen (Lu PSMA) is a novel targeted treatment for patients with metastatic castration-resistant prostate cancer (CRPC). The purpose of the study was to determine the molecular volumetric Gallium-68 (Ga) PSMA PET/CT parameters that can predict patients who will respond to treatment.
These single-center retrospective data were obtained from metastatic CRPC patients receiving intravenous 6.0-8.5 GBq Lu PSMA treatment every 6-8 weeks for a maximum of 3-8 cycles, with baseline Ga PSMA PET/CT scan, clinical data, and information on treatment responses. All lesions were divided into two groups according to the increase and decrease in PSMA expression levels of 600 bone lesions and 85 lymph nodes that were compatible with metastasis of 23 patients after the treatment. The primary endpoint of our study was the evaluation of the relation between the baseline SUVmax, PSMA TV, TL PSMA values, and the treatment response of the two groups. The threshold values were determined for the parameters that had significant relations. In the present study, the prostate-specific antigen (PSA) response and treatment-induced toxicities were also evaluated as the secondary endpoint.
It was found that SUVmax, PSMA TV, and TL PSMA values in bone metastases showed significant differences between the groups with decreased and increased PSMA expression levels after the treatment. The AUC value for SUVmax was significant (AUC = 0.677; p < 0.001). The cutoff value was > 10.50 (sensitivity = 91.8%, Specificity = 41.5%) for SUVmax, > 1.50 cm (sensitivity = 49.1%, specificity = 70%) for PSMA TV and > 8.50 g (sensitivity = %60.9, specificity = %72.2) for TL PSMA. The median SUVmax value before the treatment in all metastatic lymph nodes was found to be 7.1 (5.4-12.4), and the median SUVmax after the treatment was 2.5 (1.6-12.1) (p < 0.001).
It was shown in the present study that Lu PSMA treatment response may be higher in CRPC patients with metastatic bone lesion with high baseline PSMA expression level, and better treatment response may be achieved in patients with lymph node metastases than in bone metastases.
镥-177（Lu）前列腺特异性膜抗原（Lu PSMA）是转移性去势抵抗性前列腺癌（CRPC）患者的一种新型靶向治疗方法。本研究的目的是确定能够预测对治疗有反应患者的分子体积镓-68（Ga）PSMA PET/CT参数。
这些单中心回顾性数据来自接受静脉注射6.0 - 8.5GBq Lu PSMA治疗，每6 - 8周一次，最多3 - 8个周期的转移性CRPC患者，包括基线Ga PSMA PET/CT扫描、临床数据以及治疗反应信息。根据23例患者治疗后600处骨病变和85处淋巴结中与转移相符的PSMA表达水平的升高和降低，将所有病变分为两组。本研究的主要终点是评估基线SUVmax、PSMA TV、TL PSMA值与两组治疗反应之间的关系。确定具有显著关系的参数的阈值。在本研究中，前列腺特异性抗原（PSA）反应和治疗引起的毒性也作为次要终点进行评估。
发现骨转移中SUVmax、PSMA TV和TL PSMA值在治疗后PSMA表达水平降低和升高的组之间存在显著差异。SUVmax的AUC值具有显著性（AUC = 0.677；p < 0.001）。SUVmax的截断值>10.50（敏感性 = 91.8%，特异性 = 41.5%），PSMA TV的截断值>1.50 cm（敏感性 = 49.1%，特异性 = 70%），TL PSMA的截断值>8.50 g（敏感性 = 60.9%，特异性 = 72.2%）。发现所有转移性淋巴结治疗前的SUVmax中位数为7.1（5.4 - 12.4），治疗后的SUVmax中位数为2.5（1.6 - 12.1）（p < 0.001）。
本研究表明，基线PSMA表达水平高的转移性骨病变CRPC患者对Lu PSMA治疗的反应可能更高，且淋巴结转移患者的治疗反应可能优于骨转移患者。
