ABSTRACT
Ga-68 prostate specific membrane antigens positron emission tomography/computerized tomography (PSMA PET/CT) imaging has shown outstanding results in the staging and restaging of prostate cancer and has taken its place in guidelines. However, the value in the assessment of treatment response has not yet been determined. The criteria by “Prostate cancer clinical trial working group” has been used to evaluate the treatment response of prostate cancer. However, the results of clinical trials based on these criteria are likely to be unreliable. Furthermore, the data we have are very limited and do not seem to be comparable due to both the treatments applied and the biological status of the disease. There is also a debate on clinical progression under treatment. The importance of timing for post-treatment scan and findings in treatment response should be defined with standardization and more studies are needed to determine the place of Ga-68 PSMA PET/CT in the evaluation of treatment response.
References
1Bagguley D, Ong S, Buteau J, et al. Role of PSMA PET/CT imaging in the diagnosis, staging and restaging of prostate cancer. Future Oncol 2021;17:2225-2241.
2Perera M, Papa N, Roberts M, et al. Gallium-68 Prostate-specific Membrane Antigen Positron Emission Tomography in Advanced Prostate Cancer-Updated Diagnostic Utility, Sensitivity, Specificity, and Distribution of Prostate-specific Membrane Antigen-avid Lesions: A Systematic Review and Meta-analysis. Eur Urol 2020;77:403-417.
3Eisenhauer EA, Therasse P, Bogaerts J, et al. New response evaluation criteria in solid tumours: revised RECIST guideline (version 1.1). Eur J Cancer 2009;45:228-247.
4Wahl RL, Jacene H, Kasamon Y, Lodge MA. From RECIST to PERCIST: Evolving Considerations for PET response criteria in solid tumors. J Nucl Med 2009;50(Suppl 1):122S-150S.
5Scher HI, Halabi S, Tannock I, et al. Design and end points of clinical trials for patients with progressive prostate cancer and castrate levels of testosterone: recommendations of the Prostate Cancer Clinical Trials Working Group. J Clin Oncol 2008;26:1148-1159.
6Scher HI, Morris MJ, Stadler WM, et al. Trial Design and Objectives for Castration-Resistant Prostate Cancer: Updated Recommendations From the Prostate Cancer Clinical Trials Working Group 3. J Clin Oncol 2016;34:1402-1418.
7Hofman MS, Lawrentschuk N, Francis RJ, et al. Prostate-specific membrane antigen PET-CT in patients with high-risk prostate cancer before curative-intent surgery or radiotherapy (proPSMA): a prospective, randomised, multicentre study. Lancet 2020;395:1208-1216.
8Huggins C, Hodges CV. Studies on prostatic cancer: I. The effect of castration, of estrogen and of androgen injection on serum phosphatases in metastatic carcinoma of the prostate. 1941. J Urol 2002;168:9-12.
9Sathianathen NJ, Koschel S, Thangasamy IA, et al. Indirect Comparisons of Efficacy between Combination Approaches in Metastatic Hormone-sensitive Prostate Cancer: A Systematic Review and Network Meta-analysis. Eur Urol 2020;77:365-372.
10Neale JH, Yamamoto T. N-acetylaspartylglutamate (NAAG) and glutamate carboxypeptidase II: An abundant peptide neurotransmitter-enzyme system with multiple clinical applications. Prog Neurobiol 2020;184:101722.
11Banerjee SR, Pullambhatla M, Byun Y, et al. 68Ga-labeled inhibitors of prostate-specific membrane antigen (PSMA) for imaging prostate cancer. J Med Chem 2010;53:5333-5341.
12Silver DA, Pellicer I, Fair WR, Heston WD, Cordon-Cardo C. Prostate-specific membrane antigen expression in normal and malignant human tissues. Clin Cancer Res 1997;3:81-85.
13Wright GL Jr, Haley C, Beckett ML, Schellhammer PF. Expression of prostate-specific membrane antigen in normal, benign, and malignant prostate tissues. Urol Oncol 1995;1:18-28.
14Hupe MC, Philippi C, Roth D, et al. Expression of Prostate-Specific Membrane Antigen (PSMA) on Biopsies Is an Independent Risk Stratifier of Prostate Cancer Patients at Time of Initial Diagnosis. Front Oncol 2018;8:623.
15Demirci E, Kabasakal L, Şahin OE, et al. Can SUVmax values of Ga-68-PSMA PET/CT scan predict the clinically significant prostate cancer? Nucl Med Commun 2019;40:86-91.
16Hope TA, Truillet C, Ehman EC, et al. 68Ga-PSMA-11 PET Imaging of Response to Androgen Receptor Inhibition: First Human Experience. J Nucl Med 2017;58:81-84.
17Liu T, Wu LY, Fulton MD, Johnson JM, Berkman CE. Prolonged androgen deprivation leads to downregulation of androgen receptor and prostate-specific membrane antigen in prostate cancer cells. Int J Oncol 2012;41:2087-2092.
18Onal C, Guler OC, Torun N, Reyhan M, Yapar AF. The effect of androgen deprivation therapy on 68Ga-PSMA tracer uptake in non-metastatic prostate cancer patients. Eur J Nucl Med Mol Imaging 2020;47:632-641.
19Aggarwal R, Wei X, Kim W, et al. Heterogeneous Flare in Prostate-specific Membrane Antigen Positron Emission Tomography Tracer Uptake with Initiation of Androgen Pathway Blockade in Metastatic Prostate Cancer. Eur Urol Oncol 2018;1:78-82.
20Lückerath K, Wei L, Fendler WP, et al. Preclinical evaluation of PSMA expression in response to androgen receptor blockade for theranostics in prostate cancer. EJNMMI Res 2018;8:96.
21Murga JD, Moorji SM, Han AQ, Magargal WW, DiPippo VA, Olson WC. Synergistic co-targeting of prostate-specific membrane antigen and androgen receptor in prostate cancer. Prostate 2015;75:242-254.
22Seitz AK, Rauscher I, Haller B, et al. Preliminary results on response assessment using 68Ga-HBED-CC-PSMA PET/CT in patients with metastatic prostate cancer undergoing docetaxel chemotherapy. Eur J Nucl Med Mol Imaging 2018;45:602-612.
23Schmidkonz C, Cordes M, Schmidt D, et al. 68Ga-PSMA-11 PET/CT-derived metabolic parameters for determination of whole-body tumor burden and treatment response in prostate cancer. Eur J Nucl Med Mol Imaging 2018;45:1862-1872.
24Afshar-Oromieh A, Debus N, Uhrig M, et al. Impact of long-term androgen deprivation therapy on PSMA ligand PET/CT in patients with castration-sensitive prostate cancer. Eur J Nucl Med Mol Imaging 2018;45:2045-2054.
25Fanti S, Hadaschik B, Herrmann K. Proposal for Systemic-Therapy Response-Assessment Criteria at the Time of PSMA PET/CT Imaging: The PSMA PET Progression Criteria. J Nucl Med 2020;61:678-682.
