Department of Urology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
Department of Urology and Paediatric Urology, Julius Maximilians University Medical Centre of Würzburg, Würzburg, Germany.
Eur J Nucl Med Mol Imaging. 2018 Apr;45(4):602-612. doi: 10.1007/s00259-017-3887-x. Epub 2017 Nov 28.
To investigate the value of Ga-HBED-CC PSMA (Ga-PSMA) PET/CT for response assessment in metastatic castration-sensitive and castration-resistant prostate cancer (mCSPC and mCRPC) during docetaxel chemotherapy.
Ga-PSMA PET/CT was performed in seven mCSPC patients before and after six cycles of upfront docetaxel chemotherapy and in 16 mCRPC patients before and after three cycles of palliative docetaxel chemotherapy. Radiographic treatment response was evaluated separately on the Ga-PSMA PET and CT datasets. Changes in Ga-PSMA uptake (SUVmean) were assessed on a per-patient and a per-lesion basis using the PERCIST scoring system with slight modification. Treatment response was defined as absence of any PSMA uptake in all target lesions on posttreatment PET (complete response, CR) or a decrease in summed SUVmean of ≥30% (partial response, PR). The appearance of a new PET-positive lesion or an increase in summed SUVmean of ≥30% (progressive disease, PD) indicated nonresponse. A moderate change in summed SUVmean (between -30% and +30%) without a change in the number of target lesions was defined as stable disease (SD). For treatment response assessment on CT, RECIST1.1 criteria were used. Radiographic responses on Ga-PSMA PET [RR(PET)] and on CT [RR(CT)] were compared and correlated with biochemical response (BR). A decrease in serum PSA level of ≥50% was defined as biochemical PR.
Biochemical PR was found in six of seven patients with mCSPC (86%, 95% confidence interval 42% to 99.6%). The concordance rate was higher between BR and RR(PET) than between BR and RR(CT) (6/7 vs. 3/6 patients. Ga-PSMA PET and CT were concordant in only three patients (50%, 12% to 88%). In mCRPC patients, biochemical PR was found in six of 16 patients (38%, 15% to 65%). Outcome prediction was concordant between BR and RR(PET) in nine of 16 patients (56%), and between BR and RR(CT) in only four of 12 patients (33%) with target lesions on CT. Ga-PSMA PET and CT results corresponded in seven of 12 patients (58%, 28% to 85%).
Our preliminary results suggest that Ga-PSMA PET might be a promising method for treatment response assessment in mCSPC and mCRPC. The data indicate that for different metastatic sites, the performance of Ga-PSMA PET in response assessment might be superior to that of the conventional CT approach and could help differentiate between progressive disease and treatment response. Because of the limited number of patients, the differences revealed in our study were not statistically significant. Thus larger and prospective studies are clearly needed and warranted to confirm the value of Ga-PSMA PET as an imaging biomarker for response assessment.
探讨 Ga-HBED-CC PSMA（Ga-PSMA）正电子发射断层扫描（PET）/计算机断层扫描（CT）在多西他赛化疗期间评估转移性去势敏感型和去势抵抗型前列腺癌（mCSPC 和 mCRPC）疗效的价值。
7 例 mCSPC 患者在接受一线多西他赛化疗前和 6 个周期化疗后，以及 16 例 mCRPC 患者在接受姑息性多西他赛化疗前和 3 个周期化疗后，分别进行 Ga-PSMA PET/CT 检查。分别对 Ga-PSMA PET 和 CT 数据集进行影像学疗效评估。采用略有修改的 PERCIST 评分系统，基于每位患者和每位病灶，评估 Ga-PSMA 摄取（SUVmean）的变化。将无任何靶病灶摄取 Ga-PSMA（完全缓解，CR）或 SUVmean 总和降低≥30%（部分缓解，PR）定义为治疗有效。出现新的 PET 阳性病灶或 SUVmean 总和增加≥30%（疾病进展，PD）则提示为无效。靶病灶数量无变化，SUVmean 总和变化在-30%至+30%之间，则定义为病情稳定（SD）。CT 评估时，采用 RECIST1.1 标准。比较 Ga-PSMA PET 的疗效评估[RR（PET）]和 CT 的疗效评估[RR（CT）]，并与生化疗效（BR）相关联。血清 PSA 水平降低≥50%定义为生化缓解。
7 例 mCSPC 患者中，6 例（86%，95%置信区间 42%至 99.6%）出现 BR。BR 与 RR（PET）的一致性高于 BR 与 RR（CT）的一致性（6/7 例 vs. 3/6 例）。Ga-PSMA PET 和 CT 仅在 3 例患者（50%，12%至 88%）中一致。在 mCRPC 患者中，16 例中有 6 例（38%，15%至 65%）出现 BR。BR 与 RR（PET）在 16 例中有 9 例（56%），与 RR（CT）在 12 例中有 4 例（33%）患者中有靶病灶时的预测结果一致。Ga-PSMA PET 和 CT 在 12 例中有 7 例（58%，28%至 85%）结果一致。
初步研究结果表明，Ga-PSMA PET 可能是评估 mCSPC 和 mCRPC 治疗反应的一种很有前途的方法。数据表明，对于不同的转移部位，Ga-PSMA PET 在反应评估中的性能可能优于传统 CT 方法，并有助于区分疾病进展和治疗反应。由于患者数量有限，本研究中揭示的差异没有统计学意义。因此，需要并值得开展更大规模的前瞻性研究来证实 Ga-PSMA PET 作为评估反应的影像学生物标志物的价值。
