12:49 CET
308 - Clinical Oncology - Rapid Fire Session: Prostate - BCR only
Clinical Oncology
Sunday, October 13, 11:30 - 13:00
Type of session: Clinical Oncology Track
Topic: Clinical Oncology
Sub topic: 709 Urogenital
Chairpersons: K. Herrmann (Essen/DE), K. Goffin (Leuven/BE)

10 presentations in this session:
68Ga-PSMA PET/CT in biochemical recurrent prostate cancer: an international multi-institutional prospective study promoted by the IAEA
E. Estrada Lobato1, S. Fanti2, J. Cerci3;
1International Atomic Energy Agency, Vienna, AUSTRIA, 2Universita di Bologna, Bologna, ITALY, 3Quanta Diagnóstico e Terapia, Curitiba, BRAZIL.

Aim/Introduction: Biochemical recurrence is a major problem in patients with Prostate Cancer(PCa), rising PSA occurs in 20-30% of patients treated with radical prostatectomy and up to 60% in patients treated with external radiotherapy. Standard practice for suspected recurrence in PCa includes computed tomography(CT), bone scintigraphy(BS); MR and PET have been suggested. The most accurate tracer used so far is Prostate Specific Antigen(PSMA), but there is lack of reliable data, as most of the published studies have been limited by retrospective design, single institution approach, small sample size and lack of follow-up data/reference standard. Therefore, this prospective, multicentric, international study was planned to evaluate the accuracy of 68GaPSMA-PET/CT in evaluating patients with biochemical recurrent PCa; the study was promoted and supported by IAEA. We report the first interim analysis.
Materials and Methods: Patients with PCa who have undergone primary definitive treatment and with rising PSA were recruited in the study from 17 centres in 15 countries (Azerbaijan, Brazil, Colombia, India, Israel, Italy, Jordan, Lebanon, Malaysia, Mexico, Pakistan, Poland, South Africa, Turkey, and Uruguay); all centres obtained ethical clearance for prospective patient recruitment. Images and data were centrally reviewed; data were collected for positivity rate, detection rate, site of findings, impact on patient management and clinical follow-up. Results: 842 patients have been enrolled since 2017, while full data are available for 704 cases. Overall 68GaPSMA-PET/CT was positive in 423 (60.1%); lesions were identified locally (prostate/prostatic bed) in 169 cases; pelvic lymph nodes in 214 cases; bone in 137 cases and in other locations in 93 cases. There was a clear relationship between PSMA positivity and Gleason score: detection rate was 54.3% in patients with Gleason 7, 61.3% in Gleason 8, 76.0% in Gleason 9 and 76.9% in Gleason 10. Also, there was a clear relationship between lesions identification and PSA values: detection rate was 44.1% for PSA <1, 61,9% for PSA ≥1 and <2, 81.4% for PSA ≥2 and <4, and 87.1% in PSA >4.
Conclusion: This is the largest multicenter trial on PSMA-PET reported so far; the data are in line with existing literature regarding diagnostic performances of PSMA PET in biochemical recurrent PCa. No relevant difference of the accuracy was noted among the participating countries, while the major clinical role that PET may play in this setting was confirmed. Those preliminary data from the first international multicentric trial are supporting the benefits of the use of 68Ga-PSMA PET/CT. References: None

68Ga-PSMA PET/CT in patients with recurrent prostate cancer after radical treatment: prospective results in 1000 patients
P. Caroli1, U. De Giorgi1, M. Celli1, L. Fantini1, A. Moretti2, R. Galassi2, V. Di Iorio1, F. Ferroni1, A. Romeo1, M. Caracciolo3, G. Paganelli3, F. Matteucci1;
1IRCCS IRST, Meldola, ITALY, 2Ospedale Morgagni-Pierantoni, Forlì, ITALY, 3Ospedale S. Anna, Ferrara, ITALY.

Aim/Introduction: We studied the usefulness of 68Ga-prostate-specific membrane antigen (PSMA) PET/CT for detecting relapse in a prospective series of patients with biochemical recurrence (BCR) of prostate cancer (PCa) after radical treatment. Materials and Methods: Patients with BCR of PCa after radical surgery and/or radiotherapy with or without androgen-deprivation therapy were included in the study. 68Ga-HBED-CC-PSMA was prepared according to national regulations, good radiopharmaceutical practice (GRP) as outlined in EANM guidelines, using an Eazy® synthesis module (Eckert and Zieckert, Germany).68Ga-PSMA PET/CT scans performed from the top of the head to the mid-thigh 60 min after intravenous injection of 150 ± 50 MBq of 68Ga-PSMA were interpreted by two nuclear medicine physicians. 68Ga-PSMA PET/CT scans were performed on a Biograph mCT Flow® (Siemens Healthineers, Erlangen Germany). Acquisition was made on Flow mode (0,7 mm/sec) in 3D mode.The results were correlated with prostate-specific antigen (PSA) levels at the time of the scan (PSApet), Gleason score and patient age. When available, 68Ga-PSMA PET/CT scans were compared with 18F-choline PET/CT scans routinely performed within 1 month previously. Results: From November 2015 to October 2018, 1000 PCa patients with BCR were evaluated. Their median age was 72.4 years (+/- 10.3 years) and their median PSApet was 2 ng/ml (0,2 - 19 ng/ml). 68Ga-PSMA PET/CT localized one or more suspected PCa lesions detected in 653 patients (62.3%). Lesions limited to the pelvis, i.e. the prostate/prostate bed and/or pelvic lymph nodes (LNs), were detected in 415 patients (63%). At least one distant lesion (LNs, bone, other organs) was detected in 238 patients (37%). For PSA categories 0.2-0,5, 0,51-1, 1,01-2 and >2 ng/ml, 47,9%, 60,9%, 68,6%, and 87,3% of the scans were positive respectively. Conclusion: Our experience confirms 68Ga-PSMA PET/CT as a highly sensitive and accurate restaging tool in biochemically-relapsing prostate cancer with negative or equivocal conventional imaging also for PSA < 1.0 ng/ml.These results support the use of 68Ga-PSMA PET/CT in the clinical setting for an early localization of biochemical recurrence. References: None

The impact of clinical factors and inter-site variation on detection of recurrent prostate cancer with 18F-fluciclovine PET/CT and subsequent management decisions: data from the FALCON trial
G. Cook, FALCON study group;
King's College London, London, UNITED KINGDOM.

Aim/Introduction: The FALCON study aimed to confirm the clinical benefit of PET radiotracer, 18F-fluciclovine, through its impact on management decisions for men with recurrent prostate cancer.
Here, we explore the impact of clinical factors and variations between recruitment sites on the 18F-fluciclovine detection rate (DR) and subsequent management decisions. Materials and Methods: Data were collected at 6 UK sites from men with a first episode of prostate cancer recurrence after curative-intent treatment who were now being considered for radical salvage treatment. Patients who received androgen-deprivation therapy during the preceding 3 months were excluded. PSA and Gleason scores were recorded pre-scan.18F-Fluciclovine PET/CT was conducted and interpreted according to standard protocols. The patients’ management plans were recorded before and after scanning to document any post-scan amendments to plans. Results: In total, 104 patients (median age, 67 years; median PSA, 0.79 ng/mL; 15.4% with Gleason score ≥8) underwent 18F-fluciclovine PET/CT. Inter-site variation was noted for the number of patients recruited per site (range: 3-37), the median PSA value (inter-site range: 0.25-5.00 ng/mL), the proportion of patients with Gleason score ≥8 (inter-site range: 0-33%), the scanning equipment used (5 PET/CT systems were used across the 6 sites), and the median activity of 18F-fluciclovine administered per site (inter-site range: 343.3-373.0 MBq). The overall patient-level DR was 56%. Detection was broadly proportional to PSA and ranged from 33% (6/18) at PSA ≤0.2 to 100% (8/8) at PSA >10.0 ng/mL. Inter-site variation was also noted in DRs; across sites, the overall patient-level DR ranged from 23% to 95%, while the patient-level DR at PSA ≤1.0 ng/mL ranged from 13% to 50%. The site with the highest median PSA (5 ng/mL) reported the highest overall DR (95%). Low patient numbers limited meaningful analysis, however, Gleason scores ≤7 were associated with a lower DR (53%) compared with scores ≥8 (69%). Scores ≥9 showed the highest extraprostatic detection (31% vs 19% for scores ≤6). In total 66/104 (63%) of patients had a management change post-scan. Across sites, the proportion of patients with a post-scan management change ranged from 15% to 100%. In general, the sites with the highest DRs showed the highest proportion of post-scan management changes. Conclusion: This UK-wide study showed inter-site variation in patient characteristics, 18F-fluciclovine DR and proportion of post-scan management changes. 18F-Fluciclovine showed acceptable performance at low PSA. Lesions, particularly in extraprostatic regions were more common among patients with higher Gleason scores. References: none

68Ga-PSMA-11 PET localizes residual prostate cancer after salvage lymph node dissection in a multicenter retrospective study
A. Farolfi1, M. Weber2, F. Barbato2, H. Ilhan3, A. Gafita4, M. Eiber4, J. Calais5, A. Afshar-Oromieh6, A. Wetter7, B. Hadaschik8, D. Pianori9, S. Fanti1, U. Haberkorn10, K. Herrmann2, W. P. Fendler2;
1Nuclear Medicine Department, S.Orsola Hospital, University of Bologna, Bologna, ITALY, 2Department of Nuclear Medicine, University Hospital Essen, Essen, GERMANY, 3Department of Nuclear Medicine, University Hospital Munich, Ludwig-Maximilians-Universität (LMU), Munich, GERMANY, 4Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University Munich, Munich, GERMANY, 5Ahmanson Translational Theranostics Division, Department of Molecular and Medical Pharmacology, University of California Los Angeles (UCLA), Los Angeles, CA, UNITED STATES OF AMERICA, 6Department of Nuclear Medicine, Bern University Hospital, Bern, SWITZERLAND, 7Department of Radiology, University Hospital Essen, Essen, GERMANY, 8Department of Urology, University Hospital Essen, Essen, GERMANY, 9Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, ITALY, 10Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, GERMANY.

Aim/Introduction: In patients with prostate cancer (PCa) recurrence confined to the pelvic lymph nodes the main aim of metastases-directed therapy is to delay androgen deprivation therapy and improve cancer-specific survival. The aim of this study was to identify regions at risk for residual disease in patients with PSA persistence after salvage lymph node dissection (SLND) using 68Ga-PSMA-11 PET (PSMA-PET). Materials and Methods: 21 patients were included in this multicenter retrospective study with the following inclusion criteria: a) SLND for PCa; b) persistently elevated post-operative PSA levels (≥0.1 ng/mL) ≥6 weeks after SLND; c) PSMA-PET performed within 12 months after SLND. Moreover, a subgroup analysis was performed in 15 patients with both PSMA-PET pre-SLND and PSMA-PET post-SLND. Images analysis was performed by three independent nuclear medicine physicians applying the molecular imaging TNM system PROMISE. Lesions were confirmed by histopathology/biopsy, presence of lesion on correlative CT/MRI/bone scan or change in size/disappearance/appearance on follow-up CT/MRI/bone scan. Furthermore, management after PSMA-PET was documented when available. Results: PSMA-PET identified PCa-lesions in 81% (17/21) of patients with PSA persistence after SLND at a median PSA level of 1.1 ng/mL (IQR, 0.2-12.0 ng/mL). The probability of detection of Tr, N1, M1 or multiple lesions was positively associated with PSA PET (p=0.039). In the patient-based analysis disease confined to the pelvis was detected in 43% of patients (9/21), with predominant pelvic nodes disease (8/21, 38%). Most frequently affected pelvic nodal regions were internal iliac (8/21, 38%). In the subgroup analysis (PSMA-PET before and after SLND), 60% (9/15) of patients had at least one lesion already detected at baseline (PET persistence) and 27% (4/15) had previously undetected lesions (PET recurrence). Most frequently affected nodal regions with PET persistence were internal iliac (5/9), obturator (3/9) and external iliac (3/9). PSMA-PET was performed before SLND with a median time of 2 months (IQR, 1-2 months). Validation was available in 6/21 patients (29%) and 9/9 validated regions were true positive. Management after PSMA-PET was recorded in 8/21 patients (38%). Conclusion: In this multicenter retrospective study, 68Ga-PSMA-11 PET detected disease in more than 80% of patients with PSA persistence after salvage lymph node dissection. Most common sites of persistent disease were within the internal iliac region. Our data suggests a role for PSMA-ligand PET for both staging before salvage surgery and early restaging after salvage surgery in case of PSA persistence. References: none

Prostate-Specific Membrane Antigen Positron-Emission Tomography (PSMA-PET) in High-Risk Nonmetastatic Castration-Resistant Prostate Cancer (nmCRPC) SPARTAN-like Patients Negative by Conventional Imaging
W. Fendler1,2, M. Weber1, A. Iravani3, M. S. Hofman3, J. Calais2, J. Czernin2, H. Ilhan4, F. Saad5, E. J. Small6, M. R. Smith7, P. M. Perez6, T. A. Hope6, I. Rauscher8, A. Londhe9, A. Lopez-Gitlitz10, S. Cheng11, T. Maurer8, K. Herrmann1, B. Hadaschik12, M. Eiber8;
1Department of Nuclear Medicine, University of Duisburg-Essen and German Cancer Consortium (DKTK), partner site University Hospital Essen, Essen, GERMANY, 2Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, CA, UNITED STATES OF AMERICA, 3Department of Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, AUSTRALIA, 4Department of Nuclear Medicine, Ludwig Maximilian University, Munich, GERMANY, 5Centre Hospitalier de l'Université de Montréal, Université de Montréal, Montréal, QC, CANADA, 6Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, UNITED STATES OF AMERICA, 7Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, MA, UNITED STATES OF AMERICA, 8Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, GERMANY, 9Janssen Research & Development, Titusville, NJ, UNITED STATES OF AMERICA, 10Janssen Research & Development, Los Angeles, CA, UNITED STATES OF AMERICA, 11Janssen Research & Development, Raritan, NJ, UNITED STATES OF AMERICA, 12Department of Urology, University of Duisburg-Essen and German Cancer Consortium (DKTK), partner site University Hospital Essen, Essen, GERMANY.

Aim/Introduction: In SPARTAN, patients with nmCRPC assessed by conventional imaging benefited from the addition of apalutamide to ongoing androgen deprivation therapy (ADT).1 PSMA-PET detects localized and metastatic PC with superior sensitivity to conventional imaging. We retrospectively characterized disease extent using PSMA-PET in SPARTAN-like patients and evaluated risk factors for distant metastases (M1 disease) detected by PSMA-PET. Materials and Methods: A total of 200 patients with nmCRPC at high risk of developing metastases (prostate-specific antigen doubling time [PSADT] ≤ 10 months, or Gleason score [GS] ≥ 8) who had no identifiable extrapelvic metastases on prior conventional imaging were assessed with PSMA-PET. Detection rate on PSMA-PET, including local/pelvic and distant M1 disease, was determined. Association of baseline age ≥ 65 years, GS ≥ 8, PSA ≥ 5.5 ng/mL, PSADT ≤ 6 months, pelvic nodes (N1 disease), and prior local therapy with M1 disease in the PSMA-PET cohort was assessed using univariate and multivariate analyses. SPARTAN patients were stratified by risk factors for PSMA-PET-detected M1 disease and analyzed using Cox proportional-hazards models. Results: Baseline characteristics of PSMA-PET and SPARTAN patients were generally similar. PSMA-PET detected PC in 196/200 (98%) patients; 55% had local recurrence, 54% had N1 disease, 55% had any extrapelvic distant metastatic disease despite being negative on conventional imaging; 24% were diagnosed with local recurrence only, 29% with oligometastatic (1-3 lesions), and 46% with polymetastatic disease. PSA ≥ 5.5 ng/mL (OR, 2.0; 95% CI, 1.1-3.6; p = 0.03), pN1 disease (OR, 2.7; 95% CI, 1.2-6.0; p = 0.01), prior prostatectomy/salvage external radiation therapy (OR, 4.6; 95% CI, 2.0-11.0; p < 0.01), and prior external radiation therapy only (OR, 3.1; 95% CI, 1.5-6.2; p = 0.02) were significantly associated with M1 disease detected by PSMA-PET. All clinically relevant subgroups of SPARTAN patients, including patients with independent predictors of PSMA-PET-M1 disease, significantly benefited from apalutamide. Conclusion: PSMA-PET-positive CRPC patients were similar to those at high-risk of developing metastases from SPARTAN. Apalutamide added to ongoing ADT showed significant benefit in all clinically relevant subgroups of SPARTAN patients, including patients with risk factors for distant metastases detected by PSMA-PET but negative by conventional imaging. Therefore, apalutamide plus ADT should be considered for patients negative by conventional imaging but positive by PSMA-PET (stage migration). The added value of PSMA-PET over PSADT in patients with high-risk nmCRPC should be explored in prospective studies. References: 1. Smith et al. N Engl J Med. 2018;378:1408-1418.

Prognostic value of PSMA PET-derived skeleton tumor burden parameters for overall survival in patients undergoing radium-223 treatment
A. Gafita1, H. Wang1, M. Krönke1, W. Weber1, R. Tauber2, M. Eiber1;
1Technical University Munich, School of Medicine, Department of Nuclear Medicine, Munich, GERMANY, 2Technical University Munich, School of Medicine, Department of Urology, Munich, GERMANY.

Aim/Introduction: Prostate-specific membrane antigen (PSMA)-targeted PET imaging showed enhanced accuracy in lesion detection compared to conventional imaging in patients with prostate cancer. Radium-223 is a bone-targeted treatment for symptomatic metastatic castration-resistant prostate cancer (mCRPC) patients. Bone-scan-index (BSI) showed high predictive value for survival rate in patients undergoing radium-223. The aim of this retrospective analysis was to evaluate the prognostic value of baseline PSMA-PET derived skeleton tumor burden parameters for OS in patients undergoing radium-223. Materials and Methods: Patients who underwent radium-223, received a PSMA PET/CT and had available lab values prior to the treatment were considered. qPSMA was used for bone lesion segmentation using a fixed SUV-threshold of 3. Bone PSMA-avid tumor volume (bPSMA-TV) and bone PSMA-total lesion (bPSMA-TL) were used as output parameters. Baseline alkaline phosphatase (ALP) values were extracted from the database. Baseline tumor burden parameters were divided into two groups by medians and into tertile by 25th and 75thpercentiles. Kaplan-Meier curves and log-rank test were used to evaluate the association of bPSMA-TV, bPSMA-TL and ALP with OS. Results: Fifty-four patients were included in the analysis. Median PSMA-TV, PSMA-TL and ALP were 502mL, 3255 and 191 U/L. Median OS was 17.5 (95%CI: 3.2-43.6) months and 6 patients were alive at the end of follow-up period. When divided by medians, a trend towards a higher median survival for low vs. high tumor burden was noticed for bPSMA-TV and bPSMA-TL and ALP (19.2 vs. 16.6 months, 19.5 vs. 16.6 months and 19.2 vs. 14.2 months; p=0.33, p=0.33 and p=0.26, respectively). When divided by percentiles, a longer survival rate was noticed among patients with low (<144mL) vs. moderate vs. high (>1374mL) bPSMA-TV with a median OS of 24.4 vs. 14.2 vs. 6.8 months, respectively (p=0.003). No significant difference was noticed among patients with low (<1434) vs. moderate vs. high (>10174) bPSMA-TL with a median OS of 19.5 vs. 17.2 vs. 11.5 months, respectively (p=0.22). For ALP a significantly longer median survival was observed among patients with low (<121 U/L) vs. moderate vs. high (>393 U/L) levels: 21.4 vs. 19.5 vs. 6.8 months, respectively (p=0.01). Conclusion: Baseline PSMA PET-derived skeleton tumor burden parameters showed promising results for OS prediction. Compared to ALP, PSMA-TV showed a tendency to better differentiate survival rates in patients with high vs. moderate tumor burden. Advanced analyses including larger patients cohort are warranted to establish the role of PSMA-targeted PET imaging in the framework of radium-223. References: none

Prediction Nomogram for 68Ga-PSMA-11 PET/CT in different clinical settings of PSA failure after radical treatment for prostate cancer
F. Ceci1,2, L. Bianchi3, M. Borghesi3, G. Polverari2, A. Briganti4, A. Farolfi2, R. Schiavina3, E. Brunocilla3, P. Castellucci2, S. Fanti2;
1University of Turin, Turin, ITALY, 2Metropolitan Nuclear Medicine, S.Orsola-Malpighi Hospital, University of Bologna, Bologna, ITALY, 3Department of Urology, S.Orsola-Malpighi Hospital, University of Bologna, Bologna, ITALY, 4Unit of Urology/Division of Oncology, Urological Research Institute, IRCCS San Raffaele Hospital, Milan, ITALY.

Aim/Introduction: The prompt identification of the site of prostate cancer (PCa) recurrence with 68Ga-PSMA-11-PET/CT may change the disease management, potentially improving the survival outcomes. Objective: to develop a clinical nomogram to predict 68Ga-PSMA-11-PET/CT positivity in different clinical settings of PSA failure. Materials and Methods: Design: seven-hundred-three (n=703) PCa patients with confirmed PSA failure after radical therapy were enrolled. Each patient underwent 68Ga-PSMA-11-PET/CT to identify the site of recurrence. Patients were stratified according to different clinical settings of recurrence (first-time biochemical recurrence [BCR]: group-1; BCR after salvage therapy: group-2; biochemical persistence after radical prostatectomy [BCP]: group-3; advanced stage PCa before second-line systemic therapies: group-4). All patients never received AR-targeted therapies and chemotherapy. Outcome measurements and statistical analysis: First, we assessed 68Ga-PSMA-11-PET/CT positivity rate. Second, multivariable logistic regressions analyses were used to determine which co-variates independently predicted positive scan. Third, regression-based coefficients were used to develop a nomogram predicting positive 68Ga-PSMA-11-PET/CT result and 200 bootstrap resamples were used for internal validation. Fourth, Receiver operating characteristic (ROC) analysis was used to identify the most informative nomogram’s derived cut-off to predict the positive scan. Decision curve analysis (DCA) were implemented to quantify nomogram's clinical benefit in clinical practice. Results: 68Ga-PSMA-11-PET/CT positivity rate was 51.2 % (CI95% 46.8%-71.3%), while was 40.3% in group-1, 54% in group-2, 60.5% in group-3, 86.9% in group-4 (p<0.001). Median PSA=0.7 ng/mL (IQR 0.4-1.3). At multivariable analyses Gleason-grade, PSA, PSAdt and clinical setting were independent predictors of a positive scan (all p≤0.04). A nomogram based on covariates included in the multivariate model demonstrated a bootstrap-corrected accuracy of 82%. At ROC analysis, 40% resulted the best nomogram’s cut-off. Applying this cut-off, 282/703 patients (40.1%) would be spared 68Ga-PSMA-11-PET/CT and positive 68Ga-PSMA-11-PET/CT would be missed in 55 patients (15.3%). The sensitivity, specificity and NPV associated with 40% as cut-off were 84.7%, 66.2%, and 80.5%, respectively. Finally, in DCA, the nomogram revealed clinical net benefit when the threshold probabilities of positive 68Ga-PSMA-11-PET/CT is >10%.
Conclusion: We developed and internally validated the first nomogram aimed at predicting the likelihood of 68Ga-PSMA-11-PET/CT positivity in different stages of PSA failure. This novel nomogram proved its good accuracy to predict a positive 68Ga-PSMA-11-PET/CT results. The 40% cut off was the most informative threshold probability to predict positive 68Ga-PSMA-11-PET/CT. This tool might be markedly important as a guide to clinicians in the best use of PSMA-based PET imaging, in order to select the best treatment option. References: None

68Ga-PSMA-11 PET/CT in hormone-naïve recurrent prostate cancer: a prospective, single-center study in patients eligible for salvage therapy
F. Ceci1, D. G. Nicolotti1, E. Pilati1, A. Guarneri2, B. Lillaz3, R. Passera1, V. Liberini1, M. Finessi1, M. Bellò1, P. Gontero3, U. Ricardi2, D. Deandreis1;
1Nuclear Medicine, Department of Medical Sciences, University of Turin, Turin, ITALY, 2Radiation Oncology, Department of Oncology, University of Turin, Turin, ITALY, 3Urology, Department of Surgery, University of Turin, Turin, ITALY.

Aim/Introduction: Primary objective: to assess the efficacy of 68Ga-PSMA-11-PET/CT to detect recurrent location(s) in hormone-naïve prostate cancer (PCa) patients. Secondary objectives: 1) to evaluate changes in clinical management occurred after 68Ga-PSMA-11-PET/CT; 2) to determine which covariates independently predict positive scan; 3) to assess 68Ga-PSMA-11-PET/CT performance in different clinical setting of PSA relapse. Materials and Methods: This is a prospective, open-label, observational, single-centre study in hormone-naïve PCa patients (protocol P-5315). All patients, were recruited at the uro-oncological tumour board of University Hospital of Turin. Patients were investigated with 68Ga-PSMA-11-PET/CT at single referral centre between November 2016 and January 2019. Inclusion criteria: 1) proven PCa; 2) radical therapy (radical prostatectomy [RP] or radiotherapy); 3) proven biochemical recurrence (BCR) or biochemical persistence (BCP); 4) hormone-naïve patients; 5) PSA<1.5 ng/mL or any PSA in case of negative choline-PET/CT. Exclusion criteria: 1) not eligible for salvage therapy; 2) inability to tolerate PET scan; 3) concurrent malignancy. Changes in clinical management and definition of clinical settings of PSA relapse were defined by a single-centre tumour board. Clinical settings: BCP after RP (group-1); first-time BCR (group-2); BCR after salvage therapy (group-3). Multivariable logistic regressions analyses were used to determine independent predictors of positive 68Ga-PSMA-11-PET/CT. Results: Two-hundred twenty-three (n=223) consecutive patients have been prospectively enrolled: median PSA=0.65 ng/mL (0.2-8.9); median PSAdt=9.3 months (0.4-144.6). 96.9% received RP as primary therapy, while 3.1% received radiotherapy. Overall positivity rate for 68Ga-PSMA-11-PET/CT was 38.6% (CI95% 32.2%-45.3%). Disease confined to pelvis (prostate bed and/or lymph-nodes) was detected in 19.3% of cases, while distant locations (extra-pelvic nodes, bone or visceral) were observed in 19.3%. Overall, 153 PSMA positive lesions were detected. Secondary objectives: 1) taking into consideration clinical, laboratory and imaging data derived by 68Ga-PSMA-11-PET/CT, the multidisciplinary tumour board changed in 35.4% of cases the treatment planned prior to PET scan. 2) PSA, PSAdt and T stage≥3a were independent predictors of a positive scan (all p<0.03). The same features resulted independent predictors of distant PCa locations. 3) 68Ga-PSMA-11-PET/CT positivity rate was 56% in group-1, 23.3% in group-2, 47.2% in group-3. Positivity rate was significantly different among different clinical stages of PSA relapse (p=0.001). Conclusion: This study attested the overall good performance of 68Ga-PSMA-11-PET/CT to detect recurrent locations in hormone-naïve PCa, influencing the subsequent therapy management. PSA, PSAdt, T stage and different clinical settings should be taken into consideration by referent physicians, since these parameters showed significant association with 68Ga-PSMA-11-PET/CT positivity rate. References: None

68Ga-PSMA-11 PET-CT study in prostate cancer patients with biochemical recurrence and non-contributive 18F-Choline PET-CT: impact on therapeutic decision-making and biomarker changes
C. Rousseau1,2, A. Michaud1, M. Barbaud1, C. Morvant1, B. Maucherat1, M. Le Thiec1, D. Rusu1, A. Morel1, V. Fleury1, M. Colombié1, A. Rauscher3, M. Frindel3, P. Baumgartner3, N. Fleury4, L. Campion5, F. Kraeber-Bodéré1,2;
1ICO Cancer Center, Nuclear Medicine Unit, St Herblain, FRANCE, 2CRCINA, University of Nantes, INSERM UMR1232, CNRS-ERL6001, Nantes, FRANCE, 3ICO Cancer Center, Pharmacy Unit, St Herblain, FRANCE, 4ICO Cancer Center, DRCI, St Herblain, FRANCE, 5ICO Cancer Center, Biometrics Unit, St Herblain, FRANCE.

Aim/Introduction: The aim of this retrospective study was to investigate the impact of 68Ga-PSMA-11 PET/CT on current management of recurrence prostate cancer patients with negative PET/CT F-Choline. Materials and Methods: Eighty-nine patients with previously negative 18F-Choline (FCH) were enrolled (PSA from 0.28 to 24.6 ng/mL). PET images were recorded 1 hour after injection of 150 MBq of 68Ga-PSMA. Referring patient physician was asked about the care before and after PSMA PET imaging to determine the influence of PSMA results on therapeutic strategy. Six months after the end of treatment, a PSA assay was requested to evaluate therapeutic efficacy. Results: Sixty-nine among the 89 patients (77,5%) had a positive PSMA PET/CT. Detection rates were 85.6% and 89.4% for serum PSA levels lower than 2 ng/ml, and > 2 ng/ml, respectively. Three hundred and one lesions were detected: 235/301 in lymph nodes (78.1%), 38/301 as metastatic sites (bone, mostly on axial skeleton, or lung) (12.6%) and 28/301 in the prostate bed (9.3%). The majority of lesions were detected in lymph nodes: in particular with 71.5% pelvic nodes, on the other hand with 17.9% of para-aortic nodes and 10.6% with sus diaphragmatic location. For the para-aortic and sub-diaphragmatic node locations, initial surgical management associated with pelvic salvage radiotherapy were the most common initial management which could explain the frequently supra-pelvic node recurrence. The median number of lesions per patient was 2 [ranging from 0 to 67]. No particularity of the PSA serum level, doubling time or PSA velocity at the time of PSMA PET-CT could explain why 68Ga-PSMA PET-CT was unable to detect any suspicious tumor lesions in 20 patients. Thanks to PSMA PET/CT, therapeutic management changed in 59/69 patients (84.9%). With a follow-up of 5.7 ± 1.8 months, 62/89 (69.6%) PSA assays after treatment guided by PSMA PET-CT were collected. For 43.5% (27/62) of patients, the serum PSA level was lower than 0.2 ng/mL and a total PSA decrease of over 50% in 35 (56.5%) patients was obtained. Conclusion: Performing a PSMA PET-CT when FCH PET-CT was negative allows the recurrence localization in more 80% of patients and this had a major clinical impact, as it resulted in treatment change in more than 80% of patients as well as a significant decrease in PSA levels in more than 55% of them. References:

Multi-phasic 68Ga-PSMA PET/CT in detection of early recurrence in prostate cancer patients with PSA < 1 ng/ml: a prospective study of 105 cases
M. Beheshti1,2, R. Manafi-Farid3, F. M. Mottaghy4, W. Loidl5, H. Geinitz6, W. Langsteger7;
1Nuclear Medicine, University Hospital, RWTH University, Aachen, GERMANY, 2Nuclear Medicine, Paracelsus Medical University, Salzburg, AUSTRIA, 3Research Center for Nuclear Medicine, Tehran University of Medical Sciences, Tehran, IRAN, ISLAMIC REPUBLIC OF, 4University Hospital, RWTH University, Aachen, GERMANY, 5Urology, Ordensklinikum, Linz, AUSTRIA, 6Radiation Oncology, Ordensklinikum, Linz, AUSTRIA, 7PET-CT Center, St. Vincent's Hospital, Ordensklinikum, Linz, AUSTRIA.

Aim/Introduction: The main objective of this prospective study was to determine the impact of multi-phasic acquisition of 68Ga-PSMA PET/CT in the detection of local recurrence in prostate cancer (PCa) patients in early stage of biochemical recurrence with PSA level < 1 ng/ml. In addition, 68Ga-PSMA PET/CT positivity were correlated with clinical parameters. Materials and Methods: 105 patients (mean age 66.9±8.3) with biochemical recurrence and PSA level < 1 ng/ml were enrolled in this study. All patients have been subjected to initial prostatectomy with additional radiation therapy in 19.3% (26/135) and anti-hormonal therapy in 7.4% (10/135) through the disease course. A multi-phasic imaging including dynamic acquisition (1-8 min. p.i.) from prostate bed, standard whole-body images (60 min. p.i.) and delayed studies (120-150 min. p.i.) from pelvis, were performed. 68Ga-PSMA PET/CT positivity was also correlated with primary clinical findings (i.e. initial PSA, Gleason score, T-stage, positive surgical margin). Results: Overall, 91 lesions were detected in 47.6% (50/105) of patients, of whom 18 were classified as local recurrence, 48 as malignant lymph node in pelvis, and 25 distant metastases. The detection rates were 27.8% (5/18), 45.0% (27/60), and 66.7% (18/27) for PSA < 0.2 ng/ml, 0.2 ≤ PSA < 0.5 and 0.5 ≤ PSA < 1, respectively. Standard whole-body images showed significantly higher detection rate in the pelvic region in comparison with dynamic phase (p-value=0.039). However, there was no significant difference in 68Ga-PSMA PET positivity between standard and delayed imaging (p-value=0.38). Nevertheless, reviewing the findings in all acquisition phases resulted in better determination of the equivocal lesions leading to higher diagnostic accuracy in 21.9% (23/105) of patients. Trigger PSA and history of antiandrogen treatment were the significant predictor of 68Ga-PSMA PET/CT positivity. Conclusion: 68Ga-PSMA PET/CT revealed promising results for early detection of recurrent disease even in PCa patients with PSA ≥0.5 - <1.0 ng/ml. However, it showed limited value in cases with PSA level < 0.5 ng/ml.Stand-alone dynamic imaging seems to have no appreciable additive value in the detection of local recurrences or pelvic lymph node metastases. However, performing multi-phasic 68Ga-PSMA PET/CT imaging may provide additional information leading to better determination of findings in about 20% of PCa patients with low PSA of <1 ng/ml. References: none

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