Prostate-specific Membrane Antigen Positron Emission Tomography-detected Disease Extent and Overall Survival of Patients with High-risk Nonmetastatic Castration-resistant Prostate Cancer: An International Multicenter Retrospective Study

Previously, we demonstrated that prostate-specific membrane antigen positron emission tomography (PSMA-PET) revealed distant metastases in 109/200 patients (39% distant nodes, 24% bone, and 6% visceral organ) with nonmetastatic castration-resistant prostate cancer (nmCRPC) and high-risk features (International Society of Urological Pathology score ≥4 and/or prostate-specific antigen doubling time ≤10 mo) without metastases by conventional imaging. However, the impact of disease extent determined by PSMA-PET on patient outcomes is unknown. We followed these 200 patients for a median of 43 mo after PSMA-PET and retrospectively assessed the association between patient characteristics, PSMA-PET findings, treatment management, and outcomes using a Kaplan-Meier model and Cox multivariable regressions. Among assessed disease characteristics, polymetastatic disease (five or more distant lesions on PET) was independently associated with shorter overall survival (OS; median 61 mo vs not reached; hazard ratio [95% confidence interval], 1.81 [1.00-3.27]; p = 0.050) and time to new metastases (median 38 vs 60 mo; 1.80 [1.10-2.96]; p = 0.019), and initial pN1 status with shorter OS (55 mo vs not reached; 1.94 [1.12-3.37]; p = 0.019). Following PSMA-PET, locoregional salvage therapies were used most commonly in no/local disease (58%), and androgen receptor signaling inhibitors were used in distant metastatic disease (51%). PSMA-PET provides additional risk stratification for patients with nmCRPC. Polymetastatic disease (five or more distant lesions) is associated with worse outcomes. PATIENT SUMMARY: A novel sensitive imaging technology, called prostate-specific membrane antigen positron emission tomography (PSMA-PET), allows doctors to detect the spread of prostate cancer, known as distant metastases, earlier and more accurately than in the past. In our study, PSMA-PET detected none to many metastases in patients who were considered free of distant metastasis by conventional imaging. These findings predicted outcomes and were used to select appropriate treatment.

Early prediction of endocrine responsiveness in ER+/HER2-negative metastatic breast cancer (MBC): Pilot study with 18F-Fluoroestradiol (18F-FES) CT/PET

BACKGROUND

18F-FES PET/CT is considered an accurate diagnostic tool to determine whole-body endocrine responsiveness. In the ET-FES trial, we evaluated 18F-FES PET/CT as a predictive tool in ER+/HER2- metastatic breast cancer (MBC).

METHODS

Eligible patients underwent a 18F-FES PET/CT at baseline. Patients with SUV≥2 received single agent ET until PD; patients with SUV<2 were randomized to single agent ET (Arm A) or chemotherapy (CT) (Arm B). Primary objective was to compare the activity of first line ET versus CT in patients with 18F-FES SUV <2.

RESULTS

Overall, 147 patients were enrolled; 117 presented with 18F-FES SUV≥2 and received ET; 30 pts with SUV<2 were randomized to ET or CT. After a median follow up of 62.4 months, 104 patients (73.2%) had disease progression and 53 died (37.3%). Median PFS was 12.4 months (95%CI 3.1-59.6) in patients with SUV <2 randomised to Arm A versus 23.0 months (95%CI 7.7-30.0) in Arm B, (HR = 0.71, 95%CI 0.3 - 1.7); median PFS was 18.0 months (95%CI 11.2-23.1) in patients with SUV≥2 treated with ET. Median OS was 28.2 months (95%CI 14.2-NE) in patients with SUV <2 randomized to ET (Arm A) versus 52.8 months (95%CI 16.2-NE) in Arm B (CT). Median OS was not reached in patients with SUV≥2. 60-month OS rate was 41.6% (95%CI 10.4-71.1%) in Arm A, 42.0% (95%CI 14.0-68.2%) in Arm B and 59.6% (95%CI 48.6-69.0%) in patients with SUV≥2. In patients with SUV≥2, 60-months OS rate was 72.6% if treated with aromatase inhibitors versus 40.6% in case of fulvestrant or tamoxifen (p<0.005).

CONCLUSIONS

The ET-FES trial demonstrated that ER+/HER2- MBC patients are a heterogeneous population, with different levels of endocrine responsiveness based on 18F-FES CT/PET SUV.

Deep learning based automated delineation of the intraprostatic gross tumour volume in PSMA-PET for patients with primary prostate cancer

PURPOSE

With the increased use of focal radiation dose escalation for primary prostate cancer (PCa), accurate delineation of gross tumor volume (GTV) in prostate-specific membrane antigen PET (PSMA-PET) becomes crucial. Manual approaches are time-consuming and observer dependent. The purpose of this study was to create a deep learning model for the accurate delineation of the intraprostatic GTV in PSMA-PET.

METHODS

A 3D U-Net was trained on 128 different 18F-PSMA-1007 PET images from three different institutions. Testing was done on 52 patients including one independent internal cohort (Freiburg: n = 19) and three independent external cohorts (Dresden: n = 14 18F-PSMA-1007, Boston: Massachusetts General Hospital (MGH): n = 9 18F-DCFPyL-PSMA and Dana-Farber Cancer Institute (DFCI): n = 10 68Ga-PSMA-11). Expert contours were generated in consensus using a validated technique. CNN predictions were compared to expert contours using Dice similarity coefficient (DSC). Co-registered whole-mount histology was used for the internal testing cohort to assess sensitivity/specificity.

RESULTS

Median DSCs were Freiburg: 0.82 (IQR: 0.73-0.88), Dresden: 0.71 (IQR: 0.53-0.75), MGH: 0.80 (IQR: 0.64-0.83) and DFCI: 0.80 (IQR: 0.67-0.84), respectively. Median sensitivity for CNN and expert contours were 0.88 (IQR: 0.68-0.97) and 0.85 (IQR: 0.75-0.88) (p = 0.40), respectively. GTV volumes did not differ significantly (p > 0.1 for all comparisons). Median specificity of 0.83 (IQR: 0.57-0.97) and 0.88 (IQR: 0.69-0.98) were observed for CNN and expert contours (p = 0.014), respectively. CNN prediction took 3.81 seconds on average per patient.

CONCLUSION

The CNN was trained and tested on internal and external datasets as well as histopathology reference, achieving a fast GTV segmentation for three PSMA-PET tracers with high diagnostic accuracy comparable to manual experts.

Assessment of left ventricular function with gated myocardial perfusion SPECT and gated myocardial FDG PET in patients with left ventricular mechanical dyssynchrony

BACKGROUND

Left ventricular mechanical dyssynchrony (LVMD) and left ventricular function are intertwined. Gated myocardial perfusion SPECT (MPS) and gated fluorodeoxyglucose positron emission computed tomography (FDG PET) is an elegant way for repeated assessment of myocardial dyssynchrony and myocardial function. To the knowledge of the authors at the time this manuscript was prepared, there was no comprehensive evaluation of the interplay of LVMD and left ventricular function as measured by gated MPS and gated FDG PET; as well as no evaluation of the agreement between the two methods.

METHODS

Patients were assigned to the reference cohort (RC) and the dyssynchrony cohort (DC) based on the phase analysis results of gated MPS datasets. Subsequently left ventricular function was analyzed.

RESULTS

We demonstrated that LVMD as detected by gated MPS is associated with a significantly higher end-diastolic volume (EDV) and end-systolic volume (ESV) as well as a significantly reduced left ventricular ejection fraction (LVEF) both in gated MPS and gated FDG PET imaging. In the RC and the DC SPECT and PET showed good agreement and generally high linear correlations with regard to left ventricular volumes and LVEF. In the combined cohort (RC and DC) increasing amounts of LVMD were associated with increasing left ventricular volumes as well as a decreasing LVEF. The association was strongest for the dyssynchrony parameter Entropy.

CONCLUSIONS

We demonstrated that gated SPECT and gated PET are useful tools in the evaluation of left ventricular function in patients with LVMD as detected by gated MPS. Increasing amounts of dyssynchrony were associated with an increasingly reduced myocardial function. For repeated measurements or therapy monitoring, the methods should not be used interchangeably.

Investigation of image-based lesion and kidney dosimetry protocols for 177Lu-PSMA-I&T therapy with and without a late SPECT/CT acquisition

BACKGROUND

¹⁷⁷Lu-PSMA therapy has been successfully used to prolong the survival of patients with metastatic castration-resistant prostate cancer. Patient-specific dosimetry based on serial quantitative SPECT/CT imaging can support the understanding of dose-effect relationships. However, multiple SPECT/CT measurements can be challenging for patients, which motivates the investigation of efficient sampling schedules and their impact on dosimetry. In this study, different time samplings with respect to the number and timing of SPECT/CT acquisitions with and without a late measurement were investigated.

MATERIALS AND METHODS

In total, 43 lesions and 10 kidneys of 5 patients receiving ¹⁷⁷Lu-PSMA-I&T therapy were investigated. Whole-body SPECT/CT measurements were performed at 1, 2, 3 and 7 days post-injection. For both lesions (isocontour-based segmentation) and kidneys (CT-based segmentation), a reference model was employed including all four time points. To identify the best-matching fit function out of a pre-defined set of models, visual inspection, coefficients of variation and sum of squared errors were considered as goodness-of-fit criteria. Biologically effective doses (BEDs) calculated with different time samplings (days 1, 2, 3/1, 2, 7/1, 3, 7/2, 3, 7 and 1, 2/1, 3/1, 7) were compared to the reference.

RESULTS

The best-fit function was found to be a mono-exponential model for lesions and a bi-exponential model with a population-based parameter and two free parameters for kidneys. The BEDs calculated with the time sampling 1, 3, 7 days showed the lowest deviations from the reference for lesions with 4 ± 5%. Without day 7, still 86% of all lesions showed deviations from the reference < 10%. The outlier deviations showed a positive correlation with the effective half-life of the respective lesions. For kidneys, including days 1, 2, 3 achieved the best results with 0 ± 1%. Generally, deviations for kidneys were found to be small for all time samplings (max. 13%).

CONCLUSIONS

For combined optimization of the SPECT/CT time sampling for kidney and lesion dosimetry during ¹⁷⁷Lu-PSMA-I&T therapy, the sampling with days 1, 3, 7 showed the smallest deviation from the reference. Without a late acquisition, using the schedule with days 1, 2, 3 is likewise feasible.

An analysis of PSMA-PET/CT-positive lymph node distribution and their coverage by different elective nodal radiation volumes in postoperative prostate cancer patients

Salvage elective nodal radiotherapy (sENRT) is a treatment option for biochemical persistent or recurrent patients with lymph node metastases (LN) after prostatectomy. Possible ENRT templates were proposed by the RTOG (2009), the PIVOTAL trialists (2015) and the NRG Oncology Group (2021). The goal of this study was to analyze the distribution of PSMA-PET/CT-positive LN and to compare the templates with regard to their LN coverage. Methods: We analyzed PSMA-PET/CT scans of 105 patients with PET-positive LN treated with sENRT from 2014 to 2019. All LN were mapped in an exemplary dataset, classified by region, and assessed with regard to their potential coverage by the three ENRT templates. Primary endpoint was the number of missed LN. Secondary endpoint was the number of patients with full coverage. To compare the templates, t-test and McNemar test were used. Results: Three hundred and thirty-five LN were contoured (3.19 per patient, 95%-CI 2.43 - 3.95). Most frequently, LN were seen in the internal iliac (n = 94, 28.1%), external iliac (n = 60, 17.9%), periaortic (n = 58, 17.3%), common iliac (n = 55, 16.4%), perirectal (n = 26, 7.8%) and presacral (n = 19, 5.7%) region. The NRG template missed less LN per patient (1.01, 31.7%) than the RTOG (1.28, 40.1%, p<.001) and PIVOTAL templates (1.19, 37.3%, P = .003). No difference was observed in the number of patients with full coverage of all LN: 52 (49.5%) with the NRG template vs. 50 (47.6%) with the RTOG (P = .625) and 49 (46.7%) with the PIVOTAL template (P = .250). Conclusion: The NRG template showed better coverage than the RTOG and PIVOTAL templates. Nevertheless, in this cohort it would have missed almost one third of all contoured LN and would have resulted in incomplete coverage in half of the patients. This result underlines the importance of advanced imaging, such as PSMA-PET/CT, before sENRT and shows the need for further individualization of ENRT fields.

Comparison of somatostatin receptor expression in patients with neuroendocrine tumours with and without somatostatin analogue treatment imaged with [18F]SiTATE

Purpose

Somatostatin analogues (SSA) are frequently used in the treatment of neuroendocrine tumours. Recently, [18F]SiTATE entered the field of somatostatin receptor (SSR) positron emission tomography (PET)/computed tomography (CT) imaging. The purpose of this study was to compare the SSR-expression of differentiated gastroentero-pancreatic neuroendocrine tumours (GEP-NET) measured by [18F]SiTATE-PET/CT in patients with and without previous treatment with long-acting SSAs to evaluate if SSA treatment needs to be paused prior to [18F]SiTATE-PET/CT.

Methods

77 patients were examined with standardised [18F]SiTATE-PET/CT within clinical routine: 40 patients with long-acting SSAs up to 28 days prior to PET/CT examination and 37 patients without pre-treatment with SSAs. Maximum and mean standardized uptake values (SUVmax and SUVmean) of tumours and metastases (liver, lymphnode, mesenteric/peritoneal and bones) as well as representative background tissues (liver, spleen, adrenal gland, blood pool, small intestine, lung, bone) were measured, SUV ratios (SUVR) were calculated between tumours/metastases and liver, likewise between tumours/metastases and corresponding specific background, and compared between the two groups.

Results

SUVmean of liver (5.4 ± 1.5 vs. 6.8 ± 1.8) and spleen (17.5 ± 6.8 vs. 36.7 ± 10.3) were significantly lower (p < 0.001) and SUVmean of blood pool (1.7 ± 0.6 vs. 1.3 ± 0.3) was significantly higher (p < 0.001) in patients with SSA pre-treatment compared to patients without. No significant differences between tumour-to-liver and specific tumour-to-background SUVRs were observed between both groups (all p > 0.05).

Conclusion

In patients previously treated with SSAs, a significantly lower SSR expression ([18F]SiTATE uptake) in normal liver and spleen tissue was observed, as previously reported for 68Ga-labelled SSAs, without significant reduction of tumour-to-background contrast. Therefore, there is no evidence that SSA treatment needs to be paused prior to [18F]SiTATE-PET/CT.

The assessment of left ventricular mechanical dyssynchrony from gated 99mTc-tetrofosmin SPECT and gated 18F-FDG PET by QGS: a comparative study

BACKGROUND

Due to partly conflicting studies, further research is warranted with the QGS software package, with regard to the performance of gated FDG PET phase analysis as compared to gated MPS as well as the establishment of possible cut-off values for FDG PET to define dyssynchrony.

METHODS

Gated MPS and gated FDG PET datasets of 93 patients were analyzed with the QGS software. BW, Phase SD, and Entropy were calculated and compared between the methods. The performance of gated PET to identify dyssynchrony was measured against SPECT as reference standard. ROC analysis was performed to identify the best discriminator of dyssynchrony and to define cut-off values.

RESULTS

BW and Phase SD differed significantly between the SPECT and PET. There was no significant difference in Entropy with a high linear correlation between methods. There was only moderate agreement between SPECT and PET to identify dyssynchrony. Entropy was the best single PET parameter to predict dyssynchrony with a cut-off point at 62%.

CONCLUSION

Gated MPS and gated FDG PET can assess LVMD. The methods cannot be used interchangeably. Establishing reference ranges and cut-off values is difficult due to the lack of an external gold standard. Further prospective research is necessary.

Quantitative myocardial perfusion SPECT/CT for the assessment of myocardial tracer uptake in patients with three-vessel coronary artery disease: Initial experiences and results

BACKGROUND

To evaluate quantitative myocardial perfusion SPECT/CT datasets for routine clinical reporting and the assessment of myocardial tracer uptake in patients with severe TVCAD.

METHODS

MPS scans were reconstructed as quantitative SPECT datasets using CTs from internal (SPECT/CT, Q_INT) and external (PET/CT, Q_EXT) sources for attenuation correction. TPD was calculated and compared to the TPD from non-quantitative SPECT datasets of the same patients. SUVmax, SUVpeak, and SUVmean were compared between Q_INT and Q_EXT SPECT datasets. Global SUVmax and SUVpeak were compared between patients with and without TVCAD.

RESULTS

Quantitative reconstruction was feasible. TPD showed an excellent correlation between quantitative and non-quantitative SPECT datasets. SUVmax, SUVpeak, and SUVmean showed an excellent correlation between Q_INT and Q_EXT SPECT datasets, though mean SUVmean differed significantly between the two groups. Global SUVmax and SUVpeak were significantly reduced in patients with TVCAD.

CONCLUSIONS

Absolute quantification of myocardial tracer uptake is feasible. The method seems to be robust and principally suitable for routine clinical reporting. Quantitative SPECT might become a valuable tool for the assessment of severe coronary artery disease in a setting of balanced ischemia, where potentially life-threatening conditions might otherwise go undetected.

18F-rhPSMA-7 PET for the Detection of Biochemical Recurrence of Prostate Cancer After Curative-Intent Radiation Therapy: A Bicentric Retrospective Study

This bicentric, retrospective analysis investigated the efficacy of PET/CT with a novel theranostic prostate-specific membrane antigen (PSMA)--targeting ligand, ¹⁸F-rhPSMA-7, in patients with biochemical recurrence (BCR) of prostate cancer after curative-intent primary radiotherapy. Methods: Datasets from patients with BCR of prostate cancer after external-beam radiation therapy or brachytherapy who underwent ¹⁸F-rhPSMA-7 PET/CT at either Technical University Munich or Ludwig-Maximilians-University Munich were retrospectively reviewed by experienced nuclear medicine physicians and radiologists at both centers. The median injected activity was 299 MBq (range, 204-420 MBq), and the median uptake time was 77 min (range, 46-120 min). All lesions suggestive of recurrent prostate cancer were noted. Detection rates were correlated with patients' prostate-specific antigen (PSA) level, primary Gleason score, and prior use of androgen-deprivation therapy (ADT). Results: Ninety-seven patients were included (65 at Technical University Munich and 32 at Ludwig-Maximilians-University Munich). The median prescan PSA was 4.19 ng/mL (range, 0.1-159 ng/mL). The primary Gleason score was ≤6 in 19 patients, 7 in 25, ≥8 in 33, and unknown in 20. Thirty patients received ADT in the 6 mo preceding PET/CT. ¹⁸F-rhPSMA-7 identified lesions in 91 of 97 (94%) patients. Detection rates stratified by PSA were 88% (22/25), 97% (30/31), 90% (19/21), and 100% (20/20) for a PSA of <2, 2-<5, 5-<10, and ≥10 ng/mL, respectively. Detection rates in the subgroup of patients not meeting the Phoenix criteria for BCR were 80% (4/5), 90% (9/10), 100% (4/4), and 83% (5/6) for a PSA of <0.5, 0.5-<1, 1-<1.5, and 1.5-2 ng/mL, respectively. There were no significant differences in detection rates between patients with and without prior ADT (100% vs. 91%, P = 0.173) or patients with a Gleason score of ≤7 and a Gleason score of ≥8 (98% vs. 91%, P = 0.316).¹⁸F-rhPSMA-7 revealed local recurrence in 80% (78/97); pelvic lymph node metastases in 38% (37/97); retroperitoneal and supradiaphragmatic lymph node metastases in 9% (9/97) and 4% (4/97), respectively; bone metastases in 27% (26/97); and visceral metastases in 3% (3/97). In the subgroup of patients with a PSA of <2 ng/mL above nadir, local recurrence occurred in 76% (19/25) and pelvic lymph node metastases in 36% (9/25). Conclusion:¹⁸F-rhPSMA-7 PET/CT demonstrates high detection rates in prostate cancer patients with BCR after primary radiation therapy, even at low PSA values. Its diagnostic efficacy is comparable to published data for other PSMA ligands.

Apparent diffusion coefficients (ADC) in response assessment of transarterial radioembolization (TARE) for liver metastases of neuroendocrine tumors (NET): a feasibility study

Background

In patients with hepatic neuroendocrine tumors (NETs) locoregional therapies such as transarterial radioembolization (TARE) are increasingly applied. Response evaluation remains challenging and previous studies assessing response with diffusion-weighted imaging (DWI) have been inconclusive.

Purpose

To perform a feasibility study to evaluate if response assessment with quantitative apparent diffusion coefficient (ADC) in patients with liver metastases of NETs after TARE will be possible.

Material and Methods

Retrospectively, 43 patients with 120 target lesions who obtained abdominal magnetic resonance imaging (MRI) with DWI 39±28 days before and 74±46 days after TARE were included. Intralesional ADC (ADC_min, ADC_max, and ADC_mean) were measured for a maximum number of three lesions per patient on baseline and post-interventional DWI. Tumor response was categorized according to RECIST 1.1 and mRECIST.

Results

TARE resulted in partial remission (PR) in 23% (63%), in stable disease (SD) in 73% (23%), in progressive disease (PD) in 5% (7%) and in complete response (CR) in 0% (1%) according to RECIST 1.1 (mRECIST, respectively). ADC values increased significantly (P<0.005) after TARE in the PR group whereas there was no significant change in the PD group. Post-therapeutic ADC values of SD lesions increased significantly when evaluated by RECIST 1.1 but not if evaluated by mRECIST. Percentual changes of ADC_mean values were slightly higher for responders compared to non-responders (P<0.05).

Conclusion

ADC values seem to represent an additional marker for treatment response evaluation after TARE in patients with secondary hepatic NET. A conclusive study seems feasible though patient-based evaluation and overall survival and progression free survival as alternate primary endpoints should be considered.

Radioembolization, Principles and indications

Radioembolization is the selective application of radionuclide-loaded microspheres into liver arteries for the therapy of liver tumours and metastases. In this review, we focused on therapy planning and dosimetry, as well as the main indications of 90Y-glass and resin microspheres and 166Ho-microspheres.

Total Tumor Volume on 18F-PSMA-1007 PET as Additional Imaging Biomarker in mCRPC Patients Undergoing PSMA-Targeted Alpha Therapy with 225Ac-PSMA-I&T

Background: PSMA-based alpha therapy using 225Ac-PSMA-I&T provides treatment for metastatic castration-resistant prostate cancer (mCRPC), even after the failure of 177Lu-PSMA radioligand therapy (RLT). In clinical routine, the total tumor volume (TTV) on PSMA PET impacts therapy outcomes and plays an increasing role in mCRPC patients. Hence, we aimed to assess TTV and its changes during 225Ac-PSMA-I&T RLT. Methods: mCRPC patients undergoing RLT with 225Ac-PSMA-I&T with available 18F-PSMA-1007 PET/CT prior to therapy initiation were included. TTV was assessed in all patients using established cut-off values. Image derived, clinical and biochemistry parameters (PSA, LDH, AP, pain score) were analyzed prior to and after two cycles of 225Ac-PSMA. Changes in TTV and further parameters were directly compared and then correlated with established response criteria, such as RECIST 1.1 or mPERCIST. Results: 13 mCRPC patients were included. The median overall survival (OS) was 10 months. Prior to 225Ac-PSMA RLT, there was no significant correlation between TTV with other clinical parameters (p > 0.05 each). Between short-term survivors (STS, <10 months OS) and long-term survivors (LTS, ≥10 months OS), TTV and PSA were comparable (p = 0.592 & p = 0.286, respectively), whereas AP was significantly lower in the LTS (p = 0.029). A total of 7/13 patients completed two cycles and underwent a follow-up 18F-PSMA-1007 PET/CT. Among these patients, there was a significant decrease in TTV (median 835 vs. 201 mL, p = 0.028) and PSA (median 687 ng/dL vs. 178 ng/dL, p = 0.018) after two cycles of 225Ac-PSMA RLT. Here, percentage changes of TTV after two cycles showed no direct correlation to all other clinical parameters (p > 0.05 each). In two patients, new PET-avid lesions were detected on 18F-PSMA-1007 PET/CT. However, TTV and PSA were decreasing or stable. Conclusion: PET-derived assessment of TTV is an easily applicable imaging biomarker independent of other established parameters prior to 225Ac-PSMA RLT in these preliminary follow-up data. Even after the failure of 177Lu-PSMA, patients with extensive TTV seem to profit from RLT. All but one patient who was eligible for ≥2 cycles of 225Ac-PSMA-RLT demonstrated drastic TTV decreases without direct correlation to other biomarkers, such as serum PSA changes. Changes in TTV might hence improve the response assessment compared to standard classifiers by reflecting the current tumor load independent of the occurrence of new lesions.

ERANET JTC 2011: Submission and Activation of an International Academic Translational Project in Advanced Breast Cancer. Experience From the ET-FES Study

Background: Academic research is important to face unmet medical needs. The Oncological community encounters many hurdles in setting up multicenter investigator-driven trials mainly due to administrative complexity. The purpose of a network organization at a multinational level is to facilitate clinical trials through standardization, coordination, and education for drug development and regulatory approval.

Methods: The application of an European grant foresees the creation of a consortium which aims at facilitating multi-center academic clinical trials.

Results: The ERA-NET TRANSCAN Call 2011 on “Validation of biomarkers for personalized cancer medicine” was released on December 2011. This project included Italian, Spanish, French and German centers. The approval process included Consortium constitution, project submission, Clinical Trial Submission, and activation on a national level. The different timescales for submitting study documents in each Country and the misalignment of objections by each Competent Authority CA, generated several requests for changes to the study documents which meant amendments had to be made; as requested by the 2001/20/EC Directive, the alignment of core documents is mandatory. This procedure impacted significantly on study activation timelines. Time to first patient in was 14, 10, 28, and 31 months from the date of submission in Italy, France, Spain, and Germany, respectively. Accrual was stopped on 22nd January 2021 due to an 18F FES shortage as the primary reason but also for having exceeded the project deadlines with consequent exhaustion of the funds allocated for the project.

Conclusions: Pharmaceutical companies might be reluctant to fund research projects aimed at treatment individualization if the approval for a wider indication has already been achieved. Academic trials therefore become fundamental for promoting trials which are not attractive to big pharma. It was very difficult and time consuming to activate an academic clinical trial, for this reason, a study may become “old” as new drugs entered into the market. National institutions should promote the development of clinical research infrastructures and network with competence in regulatory, ethical, and legal skills to speed up academic research.

PSMA PET Imaging in Glioblastoma: A Preclinical Evaluation and Theranostic Outlook

Background

Prostate specific membrane antigen (PSMA) PET imaging has recently gained attention in glioblastoma (GBM) patients as a potential theranostic target for PSMA radioligand therapy. However, PSMA PET has not yet been established in a murine GBM model. Our goal was to investigate the potential of PSMA PET imaging in the syngeneic GL261 GBM model and to give an outlook regarding the potential of PMSA radioligand therapy in this model.

Methods

We performed an ¹⁸F-PSMA-1007 PET study in the orthotopic GL261 model (n=14 GBM, n=7 sham-operated mice) with imaging at day 4, 8, 11, 15, 18 and 22 post implantation. Time-activity-curves (TAC) were extracted from dynamic PET scans (0-120 min p. i.) in a subset of mice (n=4 GBM, n=3 sham-operated mice) to identify the optimal time frame for image analysis, and standardized-uptake-values (SUV) as well as tumor-to-background ratios (TBR) using contralateral normal brain as background were calculated in all mice. Additionally, computed tomography (CT), ex vivo and in vitro¹⁸F-PSMA-1007 autoradiographies (ARG) were performed.

Results

TAC analysis of GBM mice revealed a plateau of TBR values after 40 min p. i. Therefore, a 30 min time frame between 40-70 min p. i. was chosen for PET quantification. At day 15 and later, GBM mice showed a discernible PSMA PET signal on the inoculation site, with highest TBR_mean in GBM mice at day 18 (7.3 ± 1.3 vs. 1.6 ± 0.3 in shams; p=0.024). Ex vivo ARG confirmed high tracer signal in GBM compared to healthy background (TBR_mean 26.9 ± 10.5 vs. 1.6 ± 0.7 in shams at day 18/22 post implantation; p=0.002). However, absolute uptake values in the GL261 tumor remained low (e.g., SUV_mean 0.21 ± 0.04 g/ml at day 18) resulting in low ratios compared to dose-relevant organs (e.g., mean tumor-to-kidney ratio 1.5E^-2 ± 0.5E^-2).

Conclusions

Although ¹⁸F-PSMA-1007 PET imaging of GL261 tumor-bearing mice is feasible and resulted in high TBRs, absolute tumoral uptake values remained low and hint to limited applicability of the GL261 model for PSMA-directed therapy studies. Further investigations are warranted to identify suitable models for preclinical evaluation of PSMA-targeted theranostic approaches in GBM.

Course of Disease and Clinical Management of Patients with Poorly Differentiated Thyroid Carcinoma

Simple Summary

Poorly differentiated thyroid carcinoma (PDTC) represents a rare but aggressive variant of thyroid carcinoma and contributes to a significant proportion of thyroid carcinoma-associated deaths. Studies on PDTC are rare; therefore, we aim to assess the clinical course of these patients, evaluate the prognostic value of response to initial radioiodine therapy and identify risk factors for poor prognosis to optimize the clinical management of patients with PDCT.

Abstract

Background: In patients with poorly differentiated thyroid carcinoma, the clinical course and prognostic value of response to initial radioiodine therapy is evaluated. Methods: In 47 patients, clinical and imaging features were analyzed. Patients were stratified in no (NED), biochemical (B-ED) and structural evidence of disease (S-ED) assessed at the first diagnostic control and its impact on survival was evaluated. Further, possible risk factors for a shorter disease-specific survival rate (DSS) were analyzed. Results: In total, 17/47 patients consisted of NED, 10/47 were B-ED and 20/47 S-ED patients. At the last follow-up, 18/47 patients were NED, 2/47 patients B-ED and 27/47 patients S-ED. The median survival time was only reached for the S-ED group (median 3.9 years, 95%CI 2.8–5.1 years) and was not reached in the B-ED and NED groups. Metastases were diagnosed by a ¹⁸F-FDG-PET/CT scan in all cases and a multivariate analysis showed that the PET-positivity of metastases was the only significant predictor of DSS (p = 0.036). Conclusion: The response to initial surgery and radioiodine therapy in PDTC patients can achieve an excellent outcome and a further follow-up should be refined based on findings at the first diagnostic control. However, patients with an incomplete response and metastatic patients who become mostly radioiodine refractory show a significantly shorter survival, which makes accurate staging by ¹⁸F-FDG-PET/CT imaging crucial.

Outcome after PSMA-PET/CT-based salvage radiotherapy for nodal recurrence after radical prostatectomy

Purpose

Nodal recurrent prostate cancer (PCa) represents a common state of disease, amenable to local therapy. PSMA-PET/CT detects PCa recurrence at low PSA levels. The aim of this study was to evaluate the outcome of PSMA-PET/CT-based salvage radiotherapy (sRT) for lymph node (LN) recurrence.

Methods

A total of 100 consecutive patients treated with PSMA-PET/CT-based salvage elective nodal radiotherapy (sENRT) for LN recurrence were retrospectively examined. Patients underwent PSMA-PET/CT scan due to biochemical persistence (bcP, 76%) or biochemical recurrence (bcR, 24%) after radical prostatectomy (RP). Biochemical recurrence-free survival (BRFS) defined as PSA < post-RT nadir + 0.2 ng/ml and distant metastasis-free survival (DMFS) were calculated using the Kaplan–Meier method and uni- and multivariate analysis was performed.

Results

Median follow-up was 37 months. Median PSA at PSMA-PET/CT was 1.7 ng/ml (range 0.1–40.1) in patients with bcP and 1.4 ng/ml (range 0.3–5.1) in patients with bcR. PSMA-PET/CT detected 1, 2, and 3 or more LN metastases in 35%, 23%, and 42%, respectively. Eighty-three percent had only pelvic, 2% had only paraaortic, and 15% had pelvic and paraaortic LN metastases. Cumulatively, a total dose converted to EQD2_1.5 Gy of 66 Gy (60–70 Gy) was delivered to the prostatic fossa, 70 Gy (66–72 Gy) to the local recurrence, if present, 65.1 Gy (56–66 Gy) to PET-positive lymph nodes, and 47.5 Gy (42.4–50.9 Gy) to the lymphatic pathways. Concomitant androgen deprivation therapy (ADT) was administered in 83% of patients. One-, 2-, and 3-year BRFS was 80.7%, 71.6%, and 65.8%, respectively. One-, 2-, and 3-year DMFS was 91.6%, 79.1%, and 66.4%, respectively. In multivariate analysis, concomitant ADT, longer ADT duration (≥ 12 vs. < 12 months) and LN localization (pelvic vs. paraaortic) were associated with improved BRFS and concomitant ADT and lower PSA value before sRT (< 1 vs. > 1 ng/ml) with improved DMFS, respectively. No such association was seen for the number of affected lymph nodes.

Conclusions

Overall, the present analysis shows that the so far, unmatched sensitivity and specificity of PSMA-PET/CT translates in comparably high BRFS and DMFS after PSMA-PET/CT-based sENRT for patients with PCa LN recurrence. Concomitant ADT, duration of ADT, PSA value before sRT, and localization of LN metastases were significant factors for improved outcome.

Dosimetry and optimal scan time of [18F]SiTATE-PET/CT in patients with neuroendocrine tumours

PURPOSE

Radiolabelled somatostatin analogues targeting somatostatin receptors (SSR) are well established for combined positron emission tomography/computer tomography (PET/CT) imaging of neuroendocrine tumours (NET). [18F]SiTATE has recently been introduced showing high image quality, promising clinical performance and improved logistics compared to the clinical reference standard 68Ga-DOTA-TOC. Here we present the first dosimetry and optimal scan time analysis.

METHODS

Eight NET patients received a [18F]SiTATE-PET/CT (250 ± 66 MBq) with repeated emission scans (10, 30, 60, 120, 180 min after injection). Biodistribution in normal organs and SSR-positive tumour uptake were assessed. Dosimetry estimates for risk organs were determined using a combined linear-monoexponential model, and by applying 18F S-values and reference target masses for the ICRP89 adult male or female (OLINDA 2.0). Tumour-to-background ratios were compared quantitatively and visually between different scan times.

RESULTS

After 1 h, normal organs showed similar tracer uptake with only negligible changes until 3 h post-injection. In contrast, tracer uptake by tumours increased progressively for almost all types of metastases, thus increasing tumour-to-background ratios over time. Dosimetry resulted in a total effective dose of 0.015 ± 0.004 mSv/MBq. Visual evaluation revealed no clinically relevant discrepancies between later scan times, but image quality was rated highest in 60 and 120 min images.

CONCLUSION

[18F]SiTATE-PET/CT in NET shows overall high tumour-to-background ratios from 60 to 180 min after injection and an effective dose comparable to 68Ga-labelled alternatives. For clinical use of [18F]SiTATE, the best compromise between image quality and tumour-to-background contrast is reached at 120 min, followed by 60 min after injection.

[68Ga]DOTA-TATE PET for the detection of early transplant rejection in a heterotopic allograft heart transplantation model of the rat. A pilot study

BACKGROUND

The most important cause of heart transplant loss is early acute allograft rejection, caused by the infiltration of lymphocytes, development of edema and myocardial necrosis. It has been propagated that [68Ga]DOTA-TATE PET might be suitable to quantify the presence of SSTR over-expressing lymphocytes. With heterotopic allogenic heart transplant models in the rat readily available, we aimed to investigate, if monitoring and quantification of acute allograft rejection after heterotopic allogenic heart transplantation was feasible by non-invasive serial [68Ga]DOTA-TATE PET.

METHODS

17 Lewis rats (9 for serial PET imaging, 8 for histological correlation) received allogenic heterotopic heart transplants from 17 Brown-Norway rats. On days 4, 6 and 7 a [68Ga]DOTA-TATE PET scan was performed.

RESULTS

Imaging of acute transplant rejection until 7 days after allogenic heart transplantation in the rat is feasible. Heterotopic allografts showed significantly increased tracer uptake on day 4 until day 7 after transplantation, reflecting the process of histologically detected myocardial lymphocytic infiltration. Both the area of infarction and the amount of necrosis increased over the course of 7 days, with necrosis reaching statistical significance.

CONCLUSIONS

We purport that the detected PET signal is primarily a specific marker of lymphocyte infiltration and only to a lesser extent an unspecific marker of infarction and necrosis. Thus, [68Ga]DOTA-TATE PET might be a suitable tool for serial imaging and quantification of lymphocyte infiltration as a direct mediator of acute allograft rejection at an early stage after heart transplantation.

PET Imaging of Meningioma Using the Novel SSTR-Targeting Peptide 18F-SiTATE

ABSTRACT

PET using 68Ga-labeled somatostatin receptor (SSTR) ligands adds significant information in meningioma patients. 18F-SiTATE is a novel, 18F-labeled SSTR-targeting peptide with remarkable imaging properties. Here, we present a 72-year-old woman with falx meningioma and transosseous extension. 18F-SiTATE PET/CT was performed 12 months after the previous 68Ga-DOTATOC PET/CT with comparable quantitative uptake and very good spatial resolution. So far, the widespread use of SSTR ligands for NET and meningioma imaging is hampered by cost-intensive 68Ge/68Ga generators, low activity amounts, lower spatial resolution, and short half-life. 18F-SiTATE might foster widespread use of SSTR ligands, overcoming the shortcomings of 68Ga-labeled ligands.

Value of PET imaging for radiation therapy

This comprehensive review written by experts in their field gives an overview on the current status of incorporating positron emission tomography (PET) into radiation treatment planning. Moreover, it highlights ongoing studies for treatment individualisation and per-treatment tumour response monitoring for various primary tumours. Novel tracers and image analysis methods are discussed. The authors believe this contribution to be of crucial value for experts in the field as well as for policy makers deciding on the reimbursement of this powerful imaging modality.

Value of PET imaging for radiation therapy

This comprehensive review written by experts in their field gives an overview on the current status of incorporating positron emission tomography (PET) into radiation treatment planning. Moreover, it highlights ongoing studies for treatment individualisation and per-treatment tumour response monitoring for various primary tumours. Novel tracers and image analysis methods are discussed. The authors believe this contribution to be of crucial value for experts in the field as well as for policy makers deciding on the reimbursement of this powerful imaging modality.

Outcomes of metastasis-directed therapy of bone oligometastatic prostate cancer

Background

The aim of this work was to investigate the outcome of metastasis-directed radiotherapy (MDT) in prostate cancer patients with bone metastases following current ESTRO/EORTC subclassifications for oligometastatic disease.

Methods

Clinical data of 80 consecutive oligometastatic patients with 115 bone lesions receiving MDT between 2011 and 2019 were retrospectively evaluated. Hormone-sensitive (77.5%) and castrate-resistant (22.5%) patients were included. MDT was delivered with conventional fractionated or stereotactic body radiotherapy (SBRT) techniques. Kaplan–Meier method, log rank test, as well as Cox regression were used to calculate local control (LC) and biochemical and clinical progression-free survival (bPFS/cPFS).

Results

At the time of MDT 31% of patients had de-novo synchronous oligometastatic disease, 46% had de-novo metachronous oligorecurrence after primary treatment and 23% had either de-novo oligoprogressive disease, repeat oligometastatic disease or induced oligometastatic disease. The median BED₃ was 93.3 Gy (range 75.8–95.3 Gy). Concomitant ADT was administered in 69% of patients. After a median follow-up of 23 months the median bPFS and cPFS were 16.5 and 21.5 months, respectively. The 2-year LC rate was 98.3%. In multivariate analysis, age ≤ 70 (HR = 2.60, 95% CI 1.20–5.62, p = 0.015) and concomitant ADT (HR = 0.26, 95% CI 0.12–0.58, p = 0.001) significantly correlated with cPFS. Category of oligometastatic disease and hormone-sensitivity were predictive for cPFS in univariate analysis. Of 45 patients with biochemical relapse, nineteen patients (42.2%) had repeat oligometastatic disease. Fourteen patients (31%) underwent a second course of MDT. No patients experienced grade ≥ 3 toxicities.

Conclusions

MDT is safe and offers high local control rates in bone oligometastases of prostate cancer. At 2 years after treatment, more than 2 out of 5 patients are progression-free.

Trial registration Retrospectively registered.

The impact of the extent of the bone involvement on overall survival and toxicity in mCRPC patients receiving [177Lu]Lu-PSMA-617: a WARMTH multicentre study

INTRODUCTION

Prostate-specific membrane antigen (PSMA)-based radioligand therapy (RLT) showed in a multicentre WARMTH (World Association of Radiopharmaceutical and Molecular Therapy) study that the presence of bone metastases is a negative prognosticator for the survival. The current multicentre retrospective analysis aims to evaluate the response rate to RLT, the overall survival (OS) of patients and the safety of the treatment according to the extent of bone involvement.

METHODS

The study included patients with progressive metastatic castration-resistant prostate cancer (mCRPC), who underwent RLT with [¹⁷⁷Lu]Lu-PSMA-617 and a follow-up of at least 6 months. Tumour burden in the bone was classified prior to RLT as follows: less than 6 lesions, 6-20 lesions, more than 20 lesions and diffuse involvement. The response rate was evaluated using changes of the prostate-specific antigen (PSA) after the first treatment cycle. Overall survival was calculated from the date of the first treatment. Haematological adverse events were classified according to Common Terminology Criteria for Adverse Events (CTCAE), version 5.0.

RESULTS

A total of 319 males were included in the analysis. The extent of bone metastases and PSA response did not correlate significantly. Any PSA decline was observed in 73% patients; 44% showed a decline of ≥50%. The median OS of patient in the different subgroups was 18 months (less than 6 lesions), 13 months (6-20 lesions), 11 months (more than 20 lesions) and 8 months (diffuse involvement), respectively (p < 0.0001). Patients with prior Ra-223-therapy showed longer OS in all subgroups, especially in the subgroups with 6-20 lesions (OS: 16 vs. 12 months; p = 0.038) as well as diffuse involvement (OS: 11 vs. 7 months; p = 0.034). Significant negative prognosticators of OS were the existence of liver metastases in all subgroups and prior chemotherapy in patients with <6 bone lesions. Anaemia and thrombocytopenia correlated positively with the extent of bone metastases: p < 0.0001 and 0.005, respectively. No patient showed a high grade leukopenia.

CONCLUSION

The extent of bone involvement correlated negatively with the OS after RLT; however, it showed no relevant correlation with the PSA response rate. Prior therapy with Ra-223 may have a positive impact on OS. Haematotoxicity was higher in patients with more than 20 bone lesions; nevertheless, the majority of these patients did not show a relevant haematotoxicity.

Feasibility of Different Tumor Delineation Approaches for 18F-PSMA-1007 PET/CT Imaging in Prostate Cancer Patients

Background

Delineation of PSMA-positive tumor volume on PET using PSMA-ligands is of highest clinical interest as changes of PSMA-PET/CT-derived whole tumor volume (WTV) have shown to correlate with treatment response in metastatic prostate cancer patients. So far, WTV estimation was performed on PET using ⁶⁸Ga-labeled ligands; nonetheless, ¹⁸F-labeled PET ligands are gaining increasing importance due to advantages over ⁶⁸Ga-labeled compounds. However, standardized tumor delineation methods for ¹⁸F-labeled PET ligands have not been established so far. As correlation of PET-based information and morphological extent in osseous and visceral metastases is hampered by morphological delineation, low contrast in liver tissue and movement artefacts, we correlated CT-based volume of lymph node metastases (LNM) and different PET-based delineation approaches for thresholding on ¹⁸F-PSMA-1007 PET.

Methods

Fifty patients with metastatic prostate cancer, ¹⁸F-PSMA-1007 PET/CT and non-bulky LNM (short-axis diameter ≥10mm) were included. Fifty LNM were volumetrically assessed on contrast-enhanced CT (volumetric reference standard). Different approaches for tumor volume delineation were applied and correlated with the reference standard: I) fixed SUV threshold, II) isocontour thresholding relative to SUV_max (SUV%), and thresholds relative to III) liver (SUV_liver), IV) parotis (SUV_parotis) and V) spleen (SUV_spleen).

Results

A fixed SUV of 4.0 (r=0.807, r² = 0.651, p<0.001) showed the best overall association with the volumetric reference. 55% SUV_max (r=0.627, r² = 0.393, p<0.001) showed highest association using an isocontour-based threshold. Best background-based approaches were 60% SUV_liver (r=0.715, r² = 0.511, p<0.001), 80% SUV_parotis (r=0.762, r² = 0.581, p<0.001) and 60% SUV_spleen (r=0.645, r² = 0.416, p<0.001). Background tissues SUV_liver, SUV_parotis & SUV_spleen did not correlate (p>0.05 each). Recently reported cut-offs for intraprostatic tumor delineation (isocontour 44% SUV_max, 42% SUV_max and 20% SUV_max) revealed inferior association for LNM delineation.

Conclusions

A threshold of SUV 4.0 for tumor delineation showed highest association with volumetric reference standard irrespective of potential changes in PSMA-avidity of background tissues (e. g. parotis). This approach is easily applicable in clinical routine without specific software requirements. Further studies applying this approach for total tumor volume delineation are initiated.

Impact of Pharmaceutical Prophylaxis on Radiation-Induced Liver Disease Following Radioembolization

Simple Summary

Radioembolization has failed to prove survival benefit in randomized trials, and, depending on various factors including tumor biology, response rates may vary considerably. Studies showed positive correlations between survival and absorbed tumor dose. Therefore, increasing currently prescribed tumor doses may be favorable for improving patient outcomes. The dominant limiting factor for increasing RE dose prescriptions is the relatively low tolerance of liver parenchyma to radiation with the possible consequence of a radiation-induced liver disease. Advances in RILD prevention may help increasing tolerable radiation doses to improve patient outcomes. Our study aimed to evaluate the impact of post-therapeutic RILD-prophylaxis in a cohort of intensely pretreated liver metastatic breast cancer patients. The results of this study as well as pathophysiological considerations warrant further investigations of RILD prophylaxis to increase dose prescriptions in radioembolization.

Abstract

Background: Radioembolization (RE) with yttrium-90 (⁹⁰Y) resin microspheres yields heterogeneous response rates in with primary or secondary liver cancer. Radiation-induced liver disease (RILD) is a potentially life-threatening complication with higher prevalence in cirrhotics or patients exposed to previous chemotherapies. Advances in RILD prevention may help increasing tolerable radiation doses to improve patient outcomes. This study aimed to evaluate the impact of post-therapeutic RILD-prophylaxis in a cohort of intensely pretreated liver metastatic breast cancer patients; Methods: Ninety-three patients with liver metastases of breast cancer received RE between 2007 and 2016. All Patients received RILD prophylaxis for 8 weeks post-RE. From January 2014, RILD prophylaxis was changed from ursodeoxycholic acid (UDCA) and prednisolone (standard prophylaxis [SP]; n = 59) to pentoxifylline (PTX), UDCA and low-dose low molecular weight heparin (LMWH) (modified prophylaxis (MP); n = 34). The primary endpoint was toxicity including symptoms of RILD; Results: Dose exposure of normal liver parenchyma was higher in the modified vs. standard prophylaxis group (47.2 Gy (17.8–86.8) vs. 40.2 Gy (12.5–83.5), p = 0.017). All grade RILD events (mild: bilirubin ≥ 21 µmol/L (but <30 μmol/L); severe: (bilirubin ≥ 30 µmol/L and ascites)) were observed more frequently in the SP group than in the MP group, albeit without significance (7/59 vs. 1/34; p = 0.140). Severe RILD occurred in the SP group only (n = 2; p > 0.1). ALBI grade increased in 16.7% patients in the MP and in 27.1% patients in the SP group, respectively (group difference not significant); Conclusions: At established dose levels, mild or severe RILD events proved rare in our cohort. RILD prophylaxis with PTX, UDCA and LMWH appears to have an independent positive impact on OS in patients with metastatic breast cancer and may reduce the frequency and severity of RILD. Results of this study as well as pathophysiological considerations warrant further investigations of RILD prophylaxis presumably targeting combinations of anticoagulation (MP) and antiinflammation (SP) to increase dose prescriptions in radioembolization.

Influence of dosimetry method on bone lesion absorbed dose estimates in PSMA therapy: application to mCRPC patients receiving Lu-177-PSMA-I&T

BACKGROUND

Patients with metastatic, castration-resistant prostate cancer (mCRPC) present with an increased tumor burden in the skeleton. For these patients, Lutetium-177 (Lu-177) radioligand therapy targeting the prostate-specific membrane antigen (PSMA) has gained increasing interest with promising outcome data. Patient-individualized dosimetry enables improvement of therapy success with the aim of minimizing absorbed dose to organs at risk while maximizing absorbed dose to tumors. Different dosimetric approaches with varying complexity and accuracy exist for this purpose. The Medical Internal Radiation Dose (MIRD) formalism applied to tumors assumes a homogeneous activity distribution in a sphere with unit density for derivation of tumor S values (TSV). Voxel S value (VSV) approaches can account for heterogeneous activities but are simulated for a specific tissue. Full patient-individual Monte Carlo (MC) absorbed dose simulation addresses both, heterogeneous activity and density distributions. Subsequent CT-based density weighting has the potential to overcome the assumption of homogeneous density in the MIRD formalism with TSV and VSV methods, which could be a major limitation for the application in bone metastases with heterogeneous density. The aim of this investigation is a comparison of these methods for bone lesion dosimetry in mCRPC patients receiving Lu-177-PSMA therapy.

RESULTS

In total, 289 bone lesions in 15 mCRPC patients were analyzed. Percentage difference (PD) of average absorbed dose per lesion compared to MC, averaged over all lesions, was + 14 ± 10% (min: - 21%; max: + 56%) for TSVs. With lesion-individual density weighting using Hounsfield Unit (HU)-to-density conversion on the patient's CT image, PD was reduced to - 8 ± 1% (min: - 10%; max: - 3%). PD on a voxel level for three-dimensional (3D) voxel-wise dosimetry methods, averaged per lesion, revealed large PDs of + 18 ± 11% (min: - 27%; max: + 58%) for a soft tissue VSV approach compared to MC; after voxel-wise density correction, this was reduced to - 5 ± 1% (min: - 12%; max: - 2%).

CONCLUSION

Patient-individual MC absorbed dose simulation is capable to account for heterogeneous densities in bone lesions. Since the computational effort prevents its routine clinical application, TSV or VSV dosimetry approaches are used. This study showed the necessity of lesion-individual density weighting for TSV or VSV in Lu-177-PSMA therapy bone lesion dosimetry.

Correlation of an Index-Lesion-Based SPECT Dosimetry Method with Mean Tumor Dose and Clinical Outcome after 177Lu-PSMA-617 Radioligand Therapy

Background: Dosimetry can tailor prostate-specific membrane-antigen-targeted radioligand therapy (PSMA-RLT) for metastatic castration-resistant prostate cancer (mCRPC). However, whole-body tumor dosimetry is challenging in patients with a high tumor burden. We evaluate a simplified index-lesion-based single-photon emission computed tomography (SPECT) dosimetry method in correlation with clinical outcome. Methods: 30 mCRPC patients were included (median 71 years). The dosimetry was performed for the first cycle using quantitative ¹⁷⁷Lu-SPECT. The response was evaluated using RECIST 1.1 and PERCIST criteria, as well as changes in PSMA-positive tumor volume (PSMA-TV) in post-therapy PSMA-PET and biochemical response according to PSA changes after two RLT cycles. Results: Mean tumor doses as well as index-lesion doses were significantly higher in PERCIST responders compared to non-responders (10.2 ± 12.0 Gy/GBq vs. 4.0 ± 2.9 Gy/GBq, p = 0.03 and 13.7 ± 14.2 Gy/GBq vs. 5.9 ± 4.4 Gy/GBq, p = 0.04, respectively). No significant differences in mean tumor and index lesion doses were observed between responders and non-responders according to RECIST 1.1, PSMA-TV, and biochemical response criteria. Conclusion: Compared to mean tumor doses on a patient level, single index-lesion-based SPECT dosimetry correlates equally well with the response to PSMA-RLT according to PERCIST criteria and may represent a fast and feasible dosimetry approach for clinical routine.

Immature Plasma Cell Myeloma Mimics Metastatic Renal Cell Carcinoma on 18F-PSMA-1007 PET/CT Due to Endothelial PSMA-Expression

We present a 71-year-old female patient who underwent 18F-PSMA-1007 PET/CT for suspected metastatic renal cell carcinoma (RCC), as RCC also shows high PSMA-expression in tumor neovascularization. 18F-PSMA-1007 PET/CT showed a high PSMA-avidity in the renal tumor, enlarged intra-abdominal and mediastinal lymph nodes. Moreover, PSMA-positive pleural, pulmonal and osseous lesions were found. However, histopathology revealed an immature plasma cell myeloma with an endothelial PSMA-expression of the neovasculature. This case illustrates the increased PSMA-avidity in multiple myeloma and highlights PSMA as a potential theragnostic target in multiple myeloma. For clinical routine, lymphatic diseases such as extramedullary myeloma should be considered as differential diagnosis in PSMA-avid renal masses on PET/CT.

Cost-Effectiveness Analysis of 68Ga DOTA-TATE PET/CT, 111In-Pentetreotide SPECT/CT and CT for Diagnostic Workup of Neuroendocrine Tumors

Neuroendocrine tumors (NETs) are relatively rare neoplasms arising from the hormone-producing neuroendocrine system that can occur in various organs such as pancreas, small bowel, stomach and lung. As the majority of these tumors express somatostatin receptors (SSR) on their cell membrane, utilization of SSR analogs in nuclear medicine is a promising, but relatively costly approach for detection and localization. The aim of this study was to analyze the cost-effectiveness of ⁶⁸Ga-DOTA-TATE PET/CT (Gallium-68 DOTA-TATE Positron emission tomography/computed tomography) compared to ¹¹¹In-pentetreotide SPECT/CT (Indium-111 pentetreotide Single Photon emission computed tomography/computed tomography) and to CT (computed tomography) alone in detection of NETs. A decision model on the basis of Markov simulations evaluated lifetime costs and quality-adjusted life years (QALYs) related to either a CT, SPECT/CT or PET/CT. Model input parameters were obtained from publicized research projects. The analysis is grounded on the US healthcare system. Deterministic sensitivity analysis of diagnostic parameters and probabilistic sensitivity analysis predicated on a Monte Carlo simulation with 30,000 reiterations was executed. The willingness-to-pay (WTP) was determined to be $ 100,000/QALY. In the base-case investigation, PET/CT ended up with total costs of $88,003.07 with an efficacy of 4.179, whereas CT ended up with total costs of $88,894.71 with an efficacy of 4.165. SPECT/CT ended up with total costs of $89,973.34 with an efficacy of 4.158. Therefore, the strategies CT and SPECT/CT were dominated by PET/CT in the base-case scenario. In the sensitivity analyses, PET/CT remained a cost-effective strategy. This result was due to reduced therapy costs of timely detection. The additional costs of ⁶⁸Ga-DOTA-TATE PET/CT when compared to CT alone are justified in the light of potential savings in therapy costs and better outcomes.

The diagnostic challenge of coexistent sarcoidosis and thyroid cancer - a retrospective study

BACKGROUND

Sarcoid lesions may mimic metastatic disease or recurrence in thyroid cancer (TC) patients as both diseases may affect the lungs and lymph nodes. We present the first study to systematically evaluate the clinical course of patients with (TC) after adjuvant radioactive iodine therapy (RIT) and concomitant sarcoidosis of the lung or the lymph nodes.

METHODS

We screened 3285 patients and retrospectively identified 16 patients with TC (11 papillary thyroid cancer (PTC), 3 follicular thyroid cancer (FTC), 1 oncocytic PTC, 1 oncocytic FTC) and coexisting sarcoidosis of the lung and/or the lymph nodes treated at our institute. All patients had undergone thyroidectomy and initial adjuvant RIT. Challenges in diagnosing and the management of these patients were evaluated during long term follow-up (median 4.9 years (0.8-15.0 years)).

RESULTS

Median age at first diagnosis of TC was 50.1 years (33.0-71.5 years) and of sarcoidosis 39.4 years (18.0-63.9 years). During follow-up, physicians were able to differentiate between SA and persistent or recurrent TC in 10 of 16 patients (63%). Diagnosis was complicated by initial negative thyroglobulin (Tg), positive Tg antibodies and non-specific imaging findings. Histopathology can reliably distinguish between SA and TC in patients with one suspicious lesion.

CONCLUSION

Physicians should be aware of the rare coexistence of sarcoidosis and TC. Lymphadenopathy and pulmonary lesions could be metastases, sarcoidosis or even a mix of both. Therefore, this rare patient group should receive a thorough work up including histopathological clarification and, if necessary, separately for each lesion.

Liver Function Changes After Technetium-99m-Macroaggregated Albumin Administration and Their Predictive Value Regarding Hepatotoxicity in Patients Undergoing Yttrium-90-Radioembolization

BACKGROUND/AIM

Intraarterial Technetium-99m-Macroaggregated Albumin (^99mTc-MAA) administration is an established method to predict particle distribution prior to radioembolization. This study aimed to analyse the impact of intraarterial administration of ^99mTc-MAA on changes in liver-specific laboratory parameters and to assess whether such changes are associated with post-radioembolization hepatotoxicity.

PATIENTS AND METHODS

A total of 202 patients treated with radioembolization received prior mapping angiography with ^99mTc-MAA administration. All patients underwent clinical and laboratory examinations, including liver-specific parameters at certain times before and after mapping angiography/^99mTc-MAA administration, as well as before radioembolization and during follow-up.

RESULTS

Bilirubin increased temporarily after ^99mTc-MAA administration (p<0.001), but was not clinically relevant, and returned close to the initial value before radioembolization. These changes showed no association with subsequent postradioembolic hepatotoxicity or shortened overall survival.

CONCLUSION

^99mTc-MAA administration results in a significant, however, not clinically relevant transient increase in bilirubin levels, which does not provide a predictive value for subsequent radioembolization outcome or postradioembolic hepatotoxicity.

18F-FDG-PET/CT in Patients with Advanced, Radioiodine Refractory Thyroid Cancer Treated with Lenvatinib

Simple Summary

In patients with advanced radioiodine refractory differentiated thyroid carcinoma (DTC), therapeutic options are limited. In the “Study of (E7080) Lenvatinib in Differentiated Cancer of the Thyroid (SELECT)”, Lenvatinib significantly prolonged the progression-free survival, resulting in a more frequent use in clinical practice for this patient group. Due to considerable side effects, an accurate assessment of response to treatment is crucial in these patients. Therefore, we aimed to improve treatment individualization and reduce unnecessary therapies by selecting patients who will most likely benefit from Lenvatinib treatment using 2-deoxy-2-[¹⁸F] fluoro-D-glucose positron-emission-tomography/computed-tomography.

Abstract

Background: The tyrosine kinase inhibitor (TKI) Lenvatinib represents one of the most effective therapeutic options in patients with advanced radioiodine refractory differentiated thyroid carcinoma (DTC). We aimed to assess the role of 2-deoxy-2-[¹⁸F] fluoro-D-glucose positron-emission-tomography/computed-tomography (¹⁸F-FDG-PET/CT) in the monitoring of functional tumor response compared to morphological response. Methods: In 22 patients, a modified Positron Emission Tomography Response Criteria In Solid Tumors (mPERCIST) evaluation before treatment with Lenvatinib and at 3 and 6 month follow up was performed. Further PET-parameters and morphologic tumor response using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 were assessed and their prediction of progression-free survival (PFS) and disease-specific survival (DSS) was evaluated. Results: Most patients were rated stable in morphological evaluation and progressive using a metabolic response. All patients who responded to therapy through RECIST showed a decline in nearly all Positron Emission Tomography (PET)-parameters. For both time-points, non-responders according to mPERCIST showed significantly lower median PFS and DSS, whereas according to RECIST, only DSS was significantly lower. Conclusion: Tumor response assessment by ¹⁸F-FDG-PET outperforms morphological response assessment by CT in patients with advanced radioiodine refractory DTC treated with Lenvatinib, which seems to be correlated with clinical outcomes.

18F-PSMA-1007 PET/CT for response assessment in patients with metastatic renal cell carcinoma undergoing tyrosine kinase or checkpoint inhibitor therapy: preliminary results

Introduction

Tyrosine kinase (TKI) and checkpoint inhibitors (CI) prolonged overall survival in metastatic renal cell carcinoma (mRCC). Early prediction of treatment response is highly desirable for the individualization of patient management and improvement of therapeutic outcome; however, serum biochemistry is unable to predict therapeutic efficacy. Therefore, we compared ¹⁸F-PSMA-1007 PET imaging for response assessment in mRCC patients undergoing TKI or CI therapy compared to CT-based response assessment as the current imaging reference standard.

Methods

¹⁸F-PSMA-1007 PET/CT was performed in mRCC patients prior to initiation of systemic treatment and 8 weeks after therapy initiation. Treatment response was evaluated separately on ¹⁸F-PSMA-PET and CT. Changes on PSMA-PET (SUV_mean) were assessed on a per patient basis using a modified PERCIST scoring system. Complete response (CR_PET) was defined as absence of any uptake in all target lesions on posttreatment PET. Partial response (PR_PET) was defined as decrease in summed SUV_mean of > 30%. The appearance of new, PET-positive lesions or an increase in summed SUV_mean of > 30% was defined as progressive disease (PD_PET). A change in summed SUV_mean of ± 30% defined stable disease (SD_PET). RECIST 1.1 criteria were used for response assessment on CT. Results of radiographic response assessment on PSMA-PET and CT were compared.

Results

Overall, 11 mRCC patients undergoing systemic treatment were included. At baseline PSMA-PET₁, all mRCC patients showed at least one PSMA-avid lesion. On follow-up PET₂, 3 patients showed CR_PET, 3 PR_PET, 4 SD_PET, and 1 PD_PET. According to RECIST 1.1, 1 patient showed PR_CT, 9 SD_CT, and 1 PD_CT. Overall, concordant classifications were found in only 2 cases (2 SD_CT + PET). Patients with CR_PET on PET were classified as 3 SD_CT on CT using RECIST 1.1. By contrast, the patient classified as PR_CT on CT showed PSMA uptake without major changes during therapy (SD_PET). However, among 9 patients with SD_CT on CT, 3 were classified as CR_PET, 3 as PR_PET, 1 as PD_PET, and only 2 as SD_PET on PSMA-PET.

Conclusion

On PSMA-PET, heterogeneous courses were observed during systemic treatment in mRCC patients with highly diverging results compared to RECIST 1.1. In the light of missing biomarkers for early response assessment, PSMA-PET might allow more precise response assessment to systemic treatment, especially in patients classified as SD on CT.

3D image-based dosimetry for Yttrium-90 radioembolization of hepatocellular carcinoma: Impact of imaging method on absorbed dose estimates

BACKGROUND

To improve therapy outcome of Yttrium-90 selective internal radiation therapy (⁹⁰Y SIRT), patient-specific post-therapeutic dosimetry is required. For this purpose, various dosimetric approaches based on different available imaging data have been reported. The aim of this work was to compare post-therapeutic 3D absorbed dose images using Technetium-99m (^99mTc) MAA SPECT/CT, Yttrium-90 (⁹⁰Y) bremsstrahlung (BRS) SPECT/CT, and ⁹⁰Y PET/CT.

METHODS

Ten SIRTs of nine patients with unresectable hepatocellular carcinoma (HCC) were investigated. The ^99mTc SPECT/CT data, obtained from ^99mTc-MAA-based treatment simulation prior to ⁹⁰Y SIRT, were scaled with the administered ⁹⁰Y therapy activity. 3D absorbed dose images were generated by dose kernel convolution with scaled ^99mTc/⁹⁰Y SPECT/CT, ⁹⁰Y BRS SPECT/CT, and ⁹⁰Y PET/CT data of each patient. Absorbed dose estimates in tumor and healthy liver tissue obtained using the two SPECT/CT methods were compared against ⁹⁰Y PET/CT.

RESULTS

The percentage deviation of tumor absorbed dose estimates from ⁹⁰Y PET/CT values was on average -2 ± 18% for scaled ^99mTc/⁹⁰Y SPECT/CT, whereas estimates from ⁹⁰Y BRS SPECT/CT differed on average by -50 ± 13%. For healthy liver absorbed dose estimates, all three imaging methods revealed comparable values.

CONCLUSION

The quantification capabilities of the imaging data influence ⁹⁰Y SIRT tumor dosimetry, while healthy liver absorbed dose values were comparable for all investigated imaging data. When no ⁹⁰Y PET/CT image data are available, the proposed scaled ^99mTc/⁹⁰Y SPECT/CT dosimetry method was found to be more appropriate for HCC tumor dosimetry than ⁹⁰Y BRS SPECT/CT based dosimetry.

Outcome After 68Ga-PSMA-11 versus Choline PET-Based Salvage Radiotherapy in Patients with Biochemical Recurrence of Prostate Cancer: A Matched-Pair Analysis

The purpose of this analysis was primarily to analyze biochemical-recurrence free survival (BRFS) after positron emission tomography (PET)-guided salvage radiotherapy (sRT) in a large cohort, and to further compare BRFS after PSMA vs. choline PET/ computer tomography (CT)-based sRT. This retrospective analysis is based on 421 patients referred for PSMA or choline PET/CT after radical prostatectomy due to biochemically recurrent or persistent disease. BRFS (PSA: 0.2 ng/mL) was defined as the study endpoint. Cox regression analyses were performed to assess the impact of different clinical parameters on BRFS. Additionally, propensity score matching was performed to adjust patient cohorts (PSMA vs. choline PET/CT-based sRT). The median follow-up time was 30 months. BRFS at three years after sRT was 58%. In the multivariate analysis, only PSA before PET imaging and PSA before sRT were significantly associated with BRFS (p < 0.05). After propensity score matching, 272 patients were further analyzed; there was no significant difference in three-year BRFS between patients with PSMA PET-based vs. choline PET-based sRT (55% vs. 63%, p = 0.197). The present analysis confirmed the overall high BRFS rates after PET-based sRT and the strong prognostic effect of PSA level prior to sRT. PSMA PET-based sRT did not have superior BRFS rates when compared with choline PET-based sRT.

First Clinical Results for PSMA-Targeted α-Therapy Using 225Ac-PSMA-I&T in Advanced-mCRPC Patients

Treatment of advanced metastatic castration-resistant prostate cancer after failure of approved therapy options remains challenging. Prostate-specific membrane antigen (PSMA)-targeting β- and α-emitters have been introduced, with promising response rates. Here, we present the first-to our knowledge-clinical data for PSMA-targeted α-therapy (TAT) using ²²⁵Ac-PSMA imaging and therapy (I&T). Methods: Fourteen patients receiving ²²⁵Ac-PSMA-I&T were included in this retrospective analysis. Eleven of the 14 had prior second-line antiandrogen treatment with abiraterone or enzalutamide, prior chemotherapy, and prior ¹⁷⁷Lu-PSMA treatment. Patients were treated at bimonthly intervals until progression or intolerable side effects. Prostate-specific antigen (PSA) was measured for response assessment. Hematologic and nonhematologic side effects were recorded according to the Common Terminology Criteria for Adverse Events, version 5.0. Results: Thirty-four cycles of ²²⁵Ac-PSMA-I&T were applied (median dose, 7.8 MBq; range, 6.0-8.5), with 1 cycle in 3 patients, 2 cycles in 7 patients, 4 cycles in 3 patients, and 5 cycles in 1 patient. No acute toxicity was observed during hospitalization. Baseline PSA was 112 ng/mL (range, 20.5-818 ng/mL). The best PSA response after TAT (a PSA decline ≥ 50%) was observed in 7 patients, and a PSA decline of any amount was observed in 11 patients. Three patients had no PSA decline at any time. A subgroup analysis of 11 patients with prior ¹⁷⁷Lu-PSMA treatment showed any PSA decline in 8 patients and a decline of at least 50% in 5 patients. After TAT, grade 3 anemia was observed in 3 of the 14 patients, with 2 of them presenting with grade 2 anemia already at baseline. Grade 3 leukopenia was observed in 1 patient. Eight patients with preexisting xerostomia after ¹⁷⁷Lu-PSMA showed no worsening after TAT. Newly diagnosed grade 1 or 2 xerostomia after TAT was observed in 5 patients. One patient reported no xerostomia at all. Conclusion: Our first clinical data for TAT using ²²⁵Ac-PSMA-I&T showed a promising antitumor effect in advanced metastatic castration-resistant prostate cancer. These results are highly comparable to data on ²²⁵Ac-PSMA-617 TAT.

Automated production of [18F]SiTATE on a Scintomics GRP™ platform for PET/CT imaging of neuroendocrine tumors

INTRODUCTION

[¹⁸F]SiTATE (formerly known as [¹⁸F]SiFAlin-TATE) was recently introduced as a highly promising imaging agent for the diagnosis of well-differentiated neuroendocrine tumors (NET) using positron emission tomography/computed tomography (PET/CT). A high tumor uptake and excellent image quality, the straightforward labeling approach, as well as the economic and logistic advantages of ¹⁸F- over ⁶⁸Ga-labeled compounds predestinate [¹⁸F]SiTATE to become a potential new clinical reference standard. A novel state-of-the-art methodology of automated radiopharmaceutical production is required to establish [¹⁸F]SiTATE in clinical routine. This work illustrates the development of a novel synthesis procedure of [¹⁸F]SiTATE on an automated synthesis unit (ASU) and the clinical applicability of the tracer in human NET imaging.

METHODS

A new synthesis protocol was generated for the production of [¹⁸F]SiTATE on the Scintomics GRP™ platform for clinical NET imaging. The synthesis was carried out according to common Good Manufacturing Practice (GMP) guidelines including all quality control measurements. To confirm utility, clinical batches (n = 3) were produced and applied to six patients diagnosed with NET.

RESULTS

[¹⁸F]SiTATE was obtained in 54 ± 4% (n = 3) non-decay corrected radiochemical yield (RCY), with a radiochemical purity of 96.3 ± 0.1% and a molar activity (A_m) of 472 ± 45 GBq/μmol (n = 3). Quality control measurements always met the local release criteria. All specifications were taken or adapted from the Ph.Eur. regulations. PET/CT imaging with [¹⁸F]SiTATE produced on the GRP™ module confirmed the expected high image quality. The in vivo distribution pattern and excellent tumor to non-tumor contrast observed, matched the quality of the manually prepared [¹⁸F]SiTATE batches.

CONCLUSIONS

The automated manufacture of [¹⁸F]SiTATE was developed using the Scintomics GRP™ platform. The high quality of the radiotracer matched stringent quality control requirements adhering to common GMP guidelines, and its clinical applicability was confirmed by human PET/CT investigations.

ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE

The automated process for the manufacture of [¹⁸F]SiTATE described herein represents an important contribution to make [¹⁸F]SiTATE routinely accessible for its use in clinical NET diagnosis.

Radioembolization for neuroendocrine liver metastases is safe and effective prior to major hepatic resection

Background

Radioembolization (RE) is well established in the treatment of neuroendocrine liver metastases. However surgery is rarely performed after RE, although liver resection is the gold standard in the treatment of localized neuroendocrine liver metastases. Therefore, aim of the present study was to evaluate the safety and feasibility of liver resection after RE in a homogenous cohort.

Methods

From a prospective surgical (n=494) and nuclear medical (n=138) database patients with NELM who underwent liver resection and/or RE were evaluated. Between September 2011 and December 2017 eight patients could be identified who underwent liver resection after RE (mean therapeutic activity of 1,746 Mbq). Overall and progression free survival were evaluated as well as epidemiological and perioperative factors. The surgical specimens were analyzed for necrosis, fibrosis, inflammation, and steatosis.

Results

The mean hepatic tumor load of patients, who had liver surgery after RE, was 31.4% with a mean Ki-67 proliferation index of 5.9%. The majority of these patients (7/8) received whole liver RE prior to liver resection, which did not increase morbidity and mortality compared to a surgical collective. Indications for RE were oncological (6/8) or carcinoid syndrome associated reasons (2/8). Mean overall survival was 25.1 months after RE and subsequent surgery. Tumor necrosis in radioembolized lesions was 29.4% without evidence of fibrosis and inflammation in hepatic tissue.

Conclusions

This is the first study analyzing the multimodal therapeutic approach of liver resection following whole liver RE. This treatment algorithm is safe, does not lead to an increased morbidity and is associated with a favorable oncological outcome. Nonetheless, patient selection remains a key issue.

[PSMA-based theranostics for prostate cancer : From imaging to treatment]

BACKGROUND

In recent years nuclear medicine theranostics using radiolabeled prostate-specific membrane antigen (PSMA) ligands have gained increasing importance in the management of prostate cancer.

AIM

The aim of this work is to highlight the value of theranostic concepts using radiolabeled PSMA ligands for both the diagnostic work-up and treatment of advanced prostate cancer.

MATERIAL AND METHODS

The currently available knowledge in the literature is summarized and presented.

RESULTS

The use of PSMA in positron emission tomography-computed tomography (PET/CT) shows a high sensitivity and specificity for prostate cancer imaging, particularly in patients with biochemical recurrences. Furthermore, promising results are also reported for staging of primary prostate cancer and treatment monitoring. In addition, radioligand therapy using alpha and beta emitters is a promising third line treatment option in intensively pretreated patients with metastases. The reduction of side effects and optimization of the treatment sequence of radioligand therapy is of increasing importance.

CONCLUSION

Nuclear medicine theranostics have an increasing clinical impact on the diagnostics and treatment of prostate cancer.

Posterior Reversible Encephalopathy Syndrome After 90Y-Resin Microspheres Radioembolization

A 66-year-old man with colorectal carcinoma and liver-only metastases underwent radioembolization using Y-loaded, resin-based microspheres. One day after radioembolization, the patient experienced severe hypertension and multiple seizures. On MRI, symmetric edematous areas in the cerebellum and the parietal and occipital lobe were observed, a typical finding for posterior reversible encephalopathy syndrome (PRES). The PRES is associated with, for example, renal failure or blood pressure fluctuations leading to cerebral endothelial dysfunction. Antihypertensive and antiepileptic therapies led to normotensive blood pressure and neurological remission. Therefore, newly developed neurological symptoms accompanied by high blood pressure fluctuations after radioembolization should lead to PRES as differential diagnosis.

Prior therapies as prognostic factors of overall survival in metastatic castration-resistant prostate cancer patients treated with [177Lu]Lu-PSMA-617. A WARMTH multicenter study (the 617 trial)

Introduction

The impact of prior therapies, especially chemotherapy, on overall survival (OS) in patients with castration-resistant prostate cancer (CRPC) receiving [¹⁷⁷Lu]Lu-PSMA-617 therapy has been the subject of controversy. Therefore, WARMTH decided to plan a multicenter retrospective analysis (the “617 trial”) to evaluate response rate and OS as well as the impact of prior therapies on OS in more than 300 patients treated with ¹⁷⁷Lu-PSMA-617.

Materials and methods

The data of 631 metastatic CRPC (mCRPC) patients from 11 different clinics were evaluated. According to the inclusion and exclusion criteria, all patients had to have received at least abiraterone or enzalutamide prior to [¹⁷⁷Lu]Lu-PSMA-617 therapy. The patients were divided into three groups: patients who had received prior chemotherapy, patients who avoided chemotherapy, and patients for whom a chemotherapy was contraindicated.

Results

The analysis included the data of 416 patients, with a median age of 71.9 years. At the time of analysis, 87 patients (20,9%) were still alive. A total of 53.6% of patients had received both abiraterone and enzalutamide; 75.5% and 26.4% had a history of chemotherapy with docetaxel and cabazitaxel, respectively. A total of 20.4% had had Ra-223. The median OS was 11.1 months. Prior chemotherapy, the existence of bone and liver metastases, as well as Eastern Cooperative Oncology Group (ECOG) status, were significant prognosticators of worse overall survival in both univariate and multivariate analyses. Patients without any prior chemotherapy showed a significantly longer OS (14.6 months). The median OS in patients who received one or two lines of chemotherapy with docetaxel or docetaxel followed by cabazitaxel, respectively, was 10.9 months and 8.9 months. There was no difference in OS between patients who had not received chemotherapy and patients for whom chemotherapy was contraindicated. The other prior therapies did not have any significant impact on OS.

Conclusion

In the present multicenter analysis, chemotherapy-naïve mCRPC patients receiving [¹⁷⁷Lu]Lu-PSMA-617 therapy had a significantly longer OS than patients with a history of chemotherapy. This remained independent in the multivariate analysis besides presence of bone and liver metastases as negative prognosticators for survival, whereas an ECOG of 0–1 is associated with a longer OS.

Electronic supplementary material

The online version of this article (10.1007/s00259-020-04797-9) contains supplementary material, which is available to authorized users.