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The novel compound 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-ZOL (DOTA-conjugated zoledronic acid) is a promising candidate for the diagnosis and therapy of bone metastasis. The combination of the published methodology for this bisphosphonate with pharmaceutical and regulatory requirements turned out to be unexpectedly challenging. The scope of this work is the presentation and discussion of problems encountered during this process. Briefly, the radiolabelling process and purification, as well as the quality control published, did not meet the expectations. The constant effort setting up an automated radiolabelling procedure resulted in (a) an enhanced manual method using coated glass reactors, (b) a combination of three different reliable radio thin-layer chromatography (TLC) methods instead of the published and (c) a preliminary radio high-pressure liquid chromatography (HPLC) method for identification of the compound. Additionally, an automated radiolabelling process was developed, but it requires further improvement, e.g., in terms of a reactor vessel or purification of the crude product. The published purification method was found to be unsuitable for clinical routine, and an intense screening did not lead to a satisfactory result; here, more research is necessary. To sum up, implementation of DOTA-ZOL was possible but revealed a lot of critical points, of which not all could be resolved completely yet.

Background: Currently, prostate-specific membrane antigen-radioligand therapy (PSMA-RLT) is considered a last-line treatment option in advanced castration-resistant prostate cancer. Despite these patients' poor prognosis, accurate estimation of their overall survival (OS) is essential to determine whether benefits exist from the treatment and whether the loss of valuable time and unnecessary side effects can be avoided. The aim of the present study is to evaluate whether various biochemical markers can predict OS in men undergoing PSMA-RLT and whether the changes assessed after PSMA-RLT correlate with the OS., Methods: The tested tumor markers in this retrospective analysis were alkaline phosphatase (ALP), bone-specific alkaline phosphatase (BAP), prostate-specific antigen (PSA), lactate dehydrogenase (LDH), chromogranin A, and pro-gastrin-releasing peptide (pro-GRP). For the evaluation, we performed blood tests before each PSMA-RLT cycle and during follow-up visits (which were 2-3 months apart). All patients were followed up until their deaths. To test the correlations between the tumor markers and survival, we conducted the logrank tests and the multivariate Cox proportional-hazards regression model. The significance level was set at P < .05., Results: The study included 137 patients who received a total of 487 PSMA-RLT cycles between January 2015 and November 2017. Of the tested biochemical tumor markers, baseline ALP (120 U/L cut-off), LDH (248 U/L cut-off), and PSA (first quartile cut-off) correlated significantly with survival post-PSMA-RLT (P < .001 for ALP and LDH, and P = .007 for PSA). Stable and/or decreased values in most of the initially abnormal parameters were associated with significantly better OS; these parameters were ALP (P = .009), LDH (P = .005), PSA (P < .001), and pro-GRP (P = .013). The BAP and ALP responses also correlated significantly with survival in patients with bone metastases (P = .002 and P < .001, respectively). Furthermore, there was a strong correlation of the kinetic patterns of PSA, ALP, BAP, and LDH with the survival, showing that patients with steadily increasing markers had the shortest OS., Conclusion: Along with the established tumor marker PSA, ALP, LDH, BAP, and pro-GRP were correlated with the OS post-PSMA-RLT in the univariate and multivariate analyses., (© 2019 Wiley Periodicals, Inc.)

Objective: Pre-clinical studies with gallium-68 zoledronate ([ 68 Ga]Ga-DOTA ZOL ) have proposed it to be a potent bisphosphonate for PET/CT diagnosis of bone diseases and diagnostic counterpart to [ 177 Lu]Lu-DOTA ZOL and [ 225 Ac]Ac-DOTA ZOL . This study aims to be the first human biodistribution and dosimetric analysis of [ 68 Ga]Ga-DOTA ZOL ., Methods: Five metastatic skeletal disease patients (mean age: 72 years, M: F; 4:1) were injected with 150-190 MBq (4.05-5.14 mCi) of [ 68 Ga]Ga-DOTA ZOL i.v. Biodistribution of [ 68 Ga]Ga-DOTA ZOL was studied with PET/CT initial dynamic imaging for 30 min; list mode over abdomen (reconstructed as six images of 300 s) followed by static (skull to mid-thigh) imaging at 45 min and 2.5 h with Siemens Biograph 2 PET/CT camera. Also, blood samples (8 time points) and urine samples (2 time points) were collected over a period of 2.5 h. Total activity (MBq) in source organs was determined using interview fusion software (MEDISO Medical Imaging Systems, Budapest, Hungary). A blood-based method for bone marrow self-dose determination and a trapezoidal method for urinary bladder contents residence time calculation were used. OLINDA/EXM version 2.0 software (Hermes Medical Solutions, Stockholm, Sweden) was used to generate residence times for source organs, organ absorbed doses and effective doses., Results: High uptake in skeleton as target organ, kidneys and urinary bladder as organs of excretion and faint uptake in liver, spleen and salivary glands were seen. Qualitative and quantitative analysis supported fast blood clearance, high bone to soft tissue and lesion to normal bone uptake with [ 68 Ga]Ga-DOTA ZOL . Urinary bladder with the highest absorbed dose of 0.368 mSv/MBq presented the critical organ, followed by osteogenic cells, kidneys and red marrow receiving doses of 0.040, 0.031 and 0.027 mSv/MBq, respectively. The mean effective dose was found to be 0.0174 mSv/MBq which results in an effective dose of 2.61 mSv from 150 MBq., Conclusions: Biodistribution of [ 68 Ga]Ga-DOTA ZOL was comparable to [ 18 F]NaF, [ 99m Tc]Tc-MDP and [ 68 Ga]Ga-PSMA-617. With proper hydration and diuresis to reduce urinary bladder and kidney absorbed doses, it has clear advantages over [ 18 F]NaF owing to its onsite, low-cost production and theranostic potential of personalized dosimetry for treatment with [ 177 Lu]Lu-DOTA ZOL and [ 225 Ac]Ac-DOTA ZOL .

Background: Data are sparse regarding the feasibility of radioligand therapy (RLT) with [ 177 Lu]Lu-PSMA-617 as a retreatment. We aimed to assess the outcome and safety of rechallenge PSMA-RLT in patients with progressive prostatic cancer who previously benefited from this therapy., Materials and Methods: Patients who received rechallenge therapy at our department from January 2015 to March 2018 were assessed. Non-haematological and haematological adverse events were evaluated from laboratory data and clinical reports and were graded according to the Common Terminology Criteria for Adverse Events (CTCAE v. 5.0). Time to prostate-specific-antigen (PSA) progression and the overall survival (OS) rate of the study patients were calculated from the date of the first rechallenge cycle. Furthermore, the OS calculated from the first cycle baseline PSMA-RLT was compared with the survival of patients who received only baseline PSMA-RLT. The response data were determined using [ 68 Ga]Ga-PSMA-PET/CT and measurements of the tumour marker PSA., Results: Included in this retrospective study were 30 patients who were initially treated with a median of 3 cycles (range 1-5) of PSMA-RLT and were eventually retreated after a median of 6 months (range 2-26). Each patient received a median of 3 (range 1-6) rechallenge cycles. None of the patients experienced a disabling or life-threatening grade 4 adverse event according to the Common Toxicity Criteria (CTC). Grade 3 toxicity occurred in 8 patients (27%). Serious adverse events included leucopoenia (n = 2), neutropoenia (n = 1), anaemia (n = 4), thrombopenia (n = 4) and elevated renal parameters (n = 1). Irreversible adverse events occurred in 21 patients (70%). The permanent adverse events were mild/moderate (CTC grade 1/2) in 19 patients and serious (CTC grade 3) in two patients, respectively. According to PSA measurements, 75-90% of patients showed a benefit (response/stable) from the first 4 rechallenge cycles. The median OS was 12 months calculated from the first rechallenge cycle and 25 months calculated from the first cycle baseline PSMA-RLT. For comparison, the median OS in patients who received only baseline PSMA-RLT was 9 months. The difference according to the logrank test was significant: p value <0.001. Patients with a PSA decrease after the first cycle of rechallenge PSMA-RLT survived a median of 19 months, while patients with a PSA increase survived only 6 months., Conclusion: Rechallenge prostate-specific membrane antigen (PSMA) therapy has an acceptable safety profile. The majority of the retreated patients benefited from the rechallenge therapy. Patients who showed a biochemical response achieved a longer OS compared to patients who did not respond. The median OS was significantly longer in patients after rechallenge PSMA-RLT than in patients who received only baseline PSMA-RLT.

Purpose: To evaluate the use of 68 Ga-PSMA PET/CT for monitoring response to 177 Lu-617 PSMA radioligand therapy in patients with metastatic castrate-resistant prostate cancer (mCRPC)., Methods: Patients from the University Hospital Bonn and the University Hospital Aachen were retrospectively reviewed for this study. We included 48 patients with mCRPC who were treated with 177 Lu-PSMA-617 and whose records included 68 Ga-PSMA PET/CT imaging before the first and after the third or fourth treatment cycle. A treatment response based on 68 Ga-PSMA PET/CT was defined according to a modified version of the PERCIST criteria. A decline in PSA level of ≥50% was considered the reference standard. The sensitivity, specificity, positive and negative predictive values, and ROC curves were calculated, and patient survival times in relation to the PET results were also analysed., Results: 68 Ga-PSMA PET/CT had a sensitivity of about 85% and a specificity of between 55% and 65%. The negative and positive predictive values ranged between 70% and 78%. The fitted ROC area was 0.70. The survival time was about 19.6 months in patients with a treatment response, while nonresponders had a survival time of about 15.9 months. However, this difference between the groups was not statistically significant., Conclusion: Our results indicate that 68 Ga-PSMA PET/CT could be a useful tool for the evaluation of response to 177 Lu-PSMA-617 radioligand therapy within a theranostic framework.

We present the case of a 66-year-old man with castration-resistant prostate cancer, with an increasing prostate-specific antigen level, and a progressive disease during Lu-PSMA radionuclide therapy. Because the patient had a BRCA2 mutation, poly-ADP ribose polymerase inhibitor therapy was started. The patient showed a dramatic subjective and biological response to this therapy with a progression-free survival of 5 months.

In vivo pharmacokinetic analysis of [Sc]Sc-PSMA-617 was used to determine the normal organ-absorbed doses that may result from therapeutic activity of [Lu]Lu-PSMA-617 and to predict the maximum permissible activity of [Lu]Lu-PSMA-617 for patients with metastatic castration-resistant prostate carcinoma., Methods: Pharmacokinetics of [Sc]Sc-PSMA-617 was evaluated in 5 patients with metastatic castration-resistant prostate carcinoma using dynamic PET/CT, followed by 3 static PET/CT acquisitions and blood sample collection over 19.5 hours, as well as urine sample collection at 2 time points. Total activity measured in source organs by PET imaging, as well as counts per milliliter measured in blood and urine samples, was decay corrected back to the time of injection using the half-life of Sc. Afterward, forward decay correction using the half-life of Lu was performed, extrapolating the pharmacokinetics of [Sc]Sc-PSMA-617 to that of [Lu]Lu-PSMA-617. Source organs residence times and organ-absorbed doses for [Lu]Lu-PSMA-617 were calculated using OLINDA/EXM software. Bone marrow self-dose was determined with indirect blood-based method, and urinary bladder contents residence time was estimated by trapezoidal approximation. The maximum permissible activity of [Lu]Lu-PSMA-617 was calculated for each patient considering external beam radiotherapy toxicity limits for radiation absorbed doses to kidneys, bone marrow, salivary glands, and whole body., Results: The predicted mean organ-absorbed doses were highest in the kidneys (0.44 mSv/MBq), followed by the salivary glands (0.23 mSv/MBq). The maximum permissible activity was highly variable among patients; limited by whole body-absorbed dose (1 patient), marrow-absorbed dose (1 patient), and kidney-absorbed dose (3 patients)., Conclusions: [Sc]Sc-PSMA-617 PET/CT imaging is feasible and allows theoretical extrapolation of the pharmacokinetics of [Sc]Sc-PSMA-617 to that of [Lu]Lu-PSMA-617, with the intent of predicting normal organ-absorbed doses and maximum permissible activity in patients scheduled for therapy with [Lu]Lu-PSMA-617.

Aim: [Sc]Sc-PSMA-617 with 3.9-hour half-life, in vitro and in vivo characteristics similar to [Lu]Lu-PSMA-617 and possibility of delayed imaging after 24 hours or later, implies it to be advantageous than [ Ga]Ga-PSMA-617 for pretherapeutic dosimetric assessment for [Lu]Lu-PSMA-617 in metastatic castration-resistant prostate carcinoma (mCRPC) patients. In this study, we investigated biodistribution and radiation exposure to normal organs with [Sc]Sc-PSMA-617 in mCRPC patients., Methods: Five mCRPC patients (mean age, 69 years) enrolled for [Lu]Lu-PSMA-617 therapy were injected with 40-62 MBq [Sc]Sc-PSMA-617 intravenously; Siemens Biograph 2 PET/CT system was used to acquire dynamic PET data (30 minutes) in list mode over the abdomen, followed by the collection of static PET/CT images (skull to mid-thigh) at 45 minutes, 2 and approximately 20 hours postinjection. Time-dependent changes in percentage activity in source organs (kidneys, bladder, salivary glands, small intestine, liver, spleen, and whole body) were determined. Bone marrow and urinary bladder contents residence time were also calculated. Source organs residence time, organ-absorbed doses, and effective doses were determined using OLINDA/EXM software., Results: Physiological tracer uptake was seen in kidneys, liver, spleen, small intestine, urinary bladder, and salivary glands and in metastases. Kidneys with highest radiation absorbed dose of 3.19E-01 mSv/MBq were the critical organs, followed by urinary bladder wall (2.24E-01 mSv/MBq, spleen [1.85E-01], salivary glands [1.11E-01], and liver [1.07E-01] mSv/MBq). Red marrow dose was found to be 3.31E-02 mSv/MBq. The mean effective dose of 3.89E-02 mSv/MBq and effective dose of 1.95 mSv was estimated from 50 MBq (treatment planning dose) of [Sc]Sc-PSMA-617., Conclusions: [Sc]Sc-PSMA-617 is found to be a very promising radiopharmaceutical that can be used for pre [Lu]Lu-PSMA-617 therapeutic dosimetric assessment.

Purpose: Radioligand therapy (RLT) using Lutetium-177 labeled PSMA-617 (Lu-PSMA) ligand is a new therapeutic option for salvage therapy in heavily pretreated patients with metastatic castration resistant prostate cancer. The aim of this retrospective study was to analyze response in patients receiving 3 cycles of Lu-PSMA., Methods: Seventy-one patients (median age: 72 years; range 44-87) received 3 cycles of RLT with Lu-PSMA (mean administered activity: 6.016 ± 0.543 GBq) every 8 weeks. Response was evaluated using serum PSA levels and a PSA decline ≥50% was considered as biochemical response. Additionally, any PSA decline after the first cycle was evaluated for further therapy effects after the second and third cycle., Results: A total of 213 cycles were performed in 71 patients. Data for response and adverse events were available for all patients. A PSA decline ≥50% and some PSA decline occurred in 56% and 66% of the patients. Of 30 patients with a PSA response after the first cycle, 28 remained responders and 12/41 of non-responders responded to further therapy cycles., Conclusion: RLT with Lu-177-PSMA-617 shows respectable response rates. In this retrospective analysis, a relevant number of patients showed a delayed response, even if they did not respond to the first cycle of the therapy.

Aim: Our aim was to evaluate overall survival and parameters prognosticating longer survival in a large and homogeneous group of patients treated with 177 Lu-PSMA-617 radioligand therapy with heavily pretreated advanced metastatic castration resistant prostate cancer., Methods: A total of 104 patients were treated with 351 cycles of 177 Lu-PSMA-617. Prostate specific antigen (PSA) changes after the first cycle of therapy were documented prior to a second cycle. Patients were followed-up for overall survival (OS). Any PSA decline, PSA decline ≥50%, initial PSA, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), visceral metastases and cumulative injected activity were analyzed and evaluated according to OS. Multivariable analysis with parameters with a p-value ≤0.05 in univariate analysis was performed, additionally adjusting for age and presence of visceral metastases., Results: A total of 51 patients (49%) died during the observation period. The majority of patients (97%) presented with bone metastases, 77% with lymph node metastases and 32% with visceral metastases. All patients were treated with at least one line of chemotherapy. Either abiraterone or enzalutamide had been given in 100% of the patients. Any PSA decline occurred in 70 (67%) and a PSA decline ≥50% in 34 (33%) of patients after the first cycle. The median OS was 56.0 weeks (95%CI: 50.5-61.5). Initial PSA decline ≥50%, initial LDH, visceral metastases, second line chemotherapy or prior radium-223 did not have an effect on survival, whereas any initial PSA decline, initial ALP <220 U/L and cumulative injected activity ≥18.8 GBq were associated with a longer survival. A step-by-step analysis revealed a PSA decline ≥20.87% as the most noticeable cut-off prognosticating longer survival, which remained an independent prognosticator of improved OS in the multivariate analysis., Conclusion: 177 Lu-PSMA-617 RLT is a new effective therapeutic and seems to prolong survival in patients with advanced mCRPC pretreated with chemotherapy, abiraterone and/or enzalutamide.

Background: Various trivalent radiometals are well suited for labeling of DOTA-conjugated variants of Glu-ureido-based prostate-specific membrane antigen (PSMA) inhibitors. The DOTA-conjugate PSMA-617 has proven high potential in PSMA radioligand therapy (PSMA-RLT) of prostate cancer as well as PET imaging when labeled with lutetium-177 and gallium-68 respectively. Considering the relatively short physical half-life of gallium-68 this positron emitter precludes prolonged acquisition periods, as required for pre-therapeutic dosimetry or intraoperative applications. In this context, the positron emitter scandium-44 is an attractive alternative for PET imaging. We report the synthesis of [ 44 Sc]Sc-PSMA-617 as radiopharmaceutical with generator produced scandium-44, its in vitro characterization and clinical translation as part of a first in-human study., Methods: Scandium-44 was obtained from a 44 Ti/ 44 Sc radionuclide generator. PSMA-617 was labeled with 142.4±12.7 MBq of scandium-44 in analogy to [ 68 Ga]Ga-PSMA-617 and evaluated in vitro and in cell studies using PSMA+ LNCaP cells. A first-in-human investigation was subsequently carried out in a cohort of 4 patients (mean age 70±1.8 a) registered for [ 177 Lu]Lu-PSMA-617 therapy. 50.5±9.3 MBq (40 µg, 38.4 nmol) [ 44 Sc]Sc-PSMA-617 were applied via intravenous injection (i.v.), respectively. A Siemens Biograph 2 PET/CT system was used to acquire initial dynamic PET data (30 min) of abdomen in list mode followed by static PET/CT data (skull to mid-thigh) at 45 min, 2 and 18 h post-injection (p.i.). For quantitative analysis, dynamic images were reconstructed as 6 data sets of 300 s each. The noise ratio was measured in liver, lung and an additional region outside the body. SUV values in different organs and lesions were measured and compared to [ 68 Ga]Ga-PSMA-11 data of the same patients. Residence times and organ absorbed doses were calculated using OLINDA/EXM software., Results: Quantitative radiochemical yields of ≥98 % were achieved using 18 nmol of PSMA-617 after 20 min at 95 °C with apparent molar activity of 6.69±0.78 MBq/nmol. Following purification, >99 % radiochemical purity was obtained. [ 44 Sc]Sc-PSMA-617 showed high stability (>95 %) in serum for 24 h. The binding affinity and internalization fraction were determined in PSMA+ LNCaP cells (IC 50 = 4.72±0.7 nM and internalization fraction: 15.78±2.14 % IA/10 6 LNCaP cells) and compared to [ 68 Ga]Ga-PSMA-11 (12.0±2.8 nM and 9.47±2.56 % IA/10 6 LNCaP cells). Physiological tracer uptake was observed in kidneys, liver, spleen, small intestine, urinary bladder, and salivary glands and pathological uptake in both soft and skeletal metastases. SUV values were significantly lower in the kidneys (14.0) compared to [ 68 Ga]Ga-PSMA-11 OET (30.5). All other measured SUV values did not show a statistically significant difference. Tumor to liver ratios were found to lie between 1.9 and 8.3 for [ 68 Ga]Ga-PSMA-11 and between 2.5 and 8.8 for [ 44 Sc]Sc-PSMA-617 after 120 min. For [ 44 Sc]Sc-PSMA-617 the ratios were higher and no statistically significant differences were observed. Total and % activity were highest in liver followed by kidneys, spleen, small intestine and salivary glands. Rapid wash out was seen in liver and spleen and gradually over time in kidneys. Kidneys received the highest radiation absorbed dose of 0.354 (0.180-0.488) mSv/MBq. No adverse pharmacological effects were observed., Conclusion: In conclusion [ 44 Sc]Sc-PSMA-617 PET is suitable for PET imaging of prostate cancer tissue. [ 44 Sc]Sc-PSMA-617 shows promise to enable pre-therapeutic dosimetry in clinical settings. However, the clinical advantages for individual dosimetry or other applications like intraoperative applications have to be investigated in further studies., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Two castration-resistant prostate cancer patients, both with cerebral and visceral and lymphatic metastases, received multiple cycles of Lu-PSMA-617 treatments. The prognosis of both cases is dependent on brain metastases. Between Lu-PSMA-617 treatment cycles, local radiotherapy was also applied to the brain metastases. Prior to the combined therapy, all systemic metastases, including cerebral lesions, showed PSMA expression using Ga-PSMA PET/CT. Under the combined therapy, all the metastases, particularly the cerebral lesions, showed significant regression in size and PSMA expression over time.

Purpose: Up to 30% of patients with castration-resistant prostate cancer (CRPC) do not show any response to the first cycle of radioligand therapy (RLT) with [ 177 Lu]Lu-PSMA-617 (Lu-PSMA). We evaluated patient response to the second and third cycles of RLT in patients that underwent at least three cycles. The second aim of this study was to calculate the median overall survival (OS) of responders and non-responders after the first cycle and after all three cycles of RLT., Methods: CRPC patients were treated with Lu-PSMA, with a median interval of 8 weeks between each cycle. The tumour marker prostate-specific antigen (PSA) was used as the marker for response evaluation., Results: Fifty-two patients underwent a total of 190 cycles of RLT (3-6 cycles per patient). Of these, 80.8% showed a decline in PSA 2 months after the first cycle, with 44.2% showing a PSA decline of ≥50%. When compared to baseline PSA, 73.1% showed a PSA decline after the third cycle. 50% of patients that did not show any response to the first cycle also did not respond to the second and third cycles. The median OS was 60 weeks in all patients. The median OS was significantly longer for patients that showed any PSA decline after the first cycle compared to patients without PSA decline (68 vs. 33 weeks). There was a significant difference in median OS between responders and non-responders for a change in PSA after the third cycle compared to baseline PSA., Conclusion: Patients with a positive response to RLT, regardless of the rate of decline, had a significantly longer median OS. Of the patients that did not show any response to the first cycle, 50% responded to the second or third cycles.

A rare accident of a subcutaneous extravasation in the elbow with 4280 MBq Lu-PSMA-617 occurred in our clinic. We tried to reduce the damage by warming the elbow for 12 hours, then cooling it, and recommended the patient avoid exercises with the elbow for the next 3 days. We recognized a good resorption of the radionuclide in the scintigraphic imaging in the first 2 days. No pain, burning, or necrosis occurred. The administered therapy afterward showed an adequate decrease in the tumor marker level.

Background: [ 177 Lu]Lu-PSMA-617 is a well-tolerated therapy for the treatment of metastatic prostate cancer. However, because of the mainly renal excretion of the tracer, the kidneys are one of the most limiting organs. The purpose of this study was to examine the post-therapeutic changes in renal function over time and to identify risk factors for developing renal toxicity. We also tested the reliability of markers for renal function monitoring., Methods: Fifty-five patients with castrate-resistant metastatic prostate cancer treated with at least three cycles of [ 177 Lu]Lu-PSMA-617 were investigated. Renal function was assessed through laboratory tests (creatinine, GFR, cystatin C) and Tc-99 m-MAG3 measurements. Adverse events were classified according to the Common Terminology Criteria for Adverse Events (CTCAE) v4.0. To identify risk factors for renal toxicity, we used Pearson's correlation coefficient and the corresponding p values., Results: None of the 55 patients experienced severe nephrotoxicity (grade 3/4). In 14 patients (25%), we observed increased creatinine levels of CTC 1° or 2°. There were 16 cases of increased GFR (grade 1/2). At the baseline, only 14 patients had elevated cystatin C. However, post-therapeutic cystatin C was elevated in 32 patients (58%). A significant effect on renal function was found for age (p = 0.049), hypertension (p = 0.001) and pre-existing kidney disease (p = 0.001). The most reliable predictive markers of nephrotoxicity were TER-MAG3 and cystatin C., Conclusion: Renal toxicity in patients treated with [ 177 Lu]Lu-PSMA-617 was low. There was no (sub)acute grade 3 or 4 nephrotoxicity.

Radioligand therapy (RLT) with 177 Lu-PSMA-617 (PSMA is prostate-specific membrane antigen) is a novel targeted therapy for metastatic prostate cancer. In this study, we evaluated the effect of different pretherapeutic parameters on the therapeutic response measured by prostate-specific antigen (PSA) 2 mo after RLT., Methods: RLT was performed in 40 hormone-refractory patients with distant metastases and progressive disease (mean age, 71.4 y). 68 Ga-PSMA-11 PET/CT was performed in all patients 1-2 wk before RLT. All patients were treated with a mean of 6 GBq. The SUV max of tumor lesions was determined using region-of-interest analysis. Complete blood counts, renal and liver function assessments, previous therapies, pain medication, and SUVs were included in the analysis. PSA was assessed 2 mo after RLT., Results: In the univariate analysis, younger age, higher levels of γ-glutamyl transferase, lower pretherapeutic hemoglobin, a higher Gleason score, a higher number of platelets, higher C-reactive protein, regular need for pain medication, and higher lactate dehydrogenase had a negative impact on the therapeutic response; however, the multivariate analysis revealed that the most significant independent factors were the number of platelets and regular need for pain medication. The response was independent of the amount of PSMA uptake as well as previous therapies and other measured factors., Conclusion: A PSA decline of more than 50% was observed significantly more in patients without a regular need for analgesics., (© 2017 by the Society of Nuclear Medicine and Molecular Imaging.)

177 Lu-labeled PSMA-617 is a promising new therapeutic agent for radioligand therapy (RLT) of patients with metastatic castration-resistant prostate cancer (mCRPC). Initiated by the German Society of Nuclear Medicine, a retrospective multicenter data analysis was started in 2015 to evaluate efficacy and safety of 177 Lu-PSMA-617 in a large cohort of patients., Methods: One hundred forty-five patients (median age, 73 y; range, 43-88 y) with mCRPC were treated with 177 Lu-PSMA-617 in 12 therapy centers between February 2014 and July 2015 with 1-4 therapy cycles and an activity range of 2-8 GBq per cycle. Toxicity was categorized by the common toxicity criteria for adverse events (version 4.0) on the basis of serial blood tests and the attending physician's report. The primary endpoint for efficacy was biochemical response as defined by a prostate-specific antigen decline ≥ 50% from baseline to at least 2 wk after the start of RLT., Results: A total of 248 therapy cycles were performed in 145 patients. Data for biochemical response in 99 patients as well as data for physician-reported and laboratory-based toxicity in 145 and 121 patients, respectively, were available. The median follow-up was 16 wk (range, 2-30 wk). Nineteen patients died during the observation period. Grade 3-4 hematotoxicity occurred in 18 patients: 10%, 4%, and 3% of the patients experienced anemia, thrombocytopenia, and leukopenia, respectively. Xerostomia occurred in 8%. The overall biochemical response rate was 45% after all therapy cycles, whereas 40% of patients already responded after a single cycle. Elevated alkaline phosphatase and the presence of visceral metastases were negative predictors and the total number of therapy cycles positive predictors of biochemical response., Conclusion: The present retrospective multicenter study of 177 Lu-PSMA-617 RLT demonstrates favorable safety and high efficacy exceeding those of other third-line systemic therapies in mCRPC patients. Future phase II/III studies are warranted to elucidate the survival benefit of this new therapy in patients with mCRPC., (© 2017 by the Society of Nuclear Medicine and Molecular Imaging.)

An 81-year-old castrate-resistant prostate cancer man with multiple lymph node, bone, and hepatic metastases received four cycles of Lu-PSMA-617 treatments at our department from May to December 2015. All of his liver metastases showed PSMA expression in Ga-PSMA PET performed before the first cycle. Under this therapy, all of the metastases showed significant regression in size and PSMA expression over time.

An 80-year-old patient with castrate-resistant prostate cancer presented to our department for PSMA imaging because of a rising prostate-specific antigen (PSA) level. The tumor was diagnosed in 2004. GnRh analog was the only treatment the patient received. Two cycles of Lu-PSMA-617 were performed with a 2-month interval in between. Ten months after finishing with 2 cycles of Lu-PSMA therapy, we noticed a continuous falling PSA level and a decreasing tumor spread in the PET/CT imaging just under the hormone therapy.

A 75-year-old man with castrate-resistant prostate cancer and increasing prostate-specific antigen (PSA) level developed severe bone marrow depression during Ra radionuclide therapy. Because of this, he was treated with Lu-PSMA in compassionate use for this not-yet-approved therapy. At the beginning of Lu-PSMA therapy, repeated blood transfusions (BT) were necessary. Six months after the last BT, after 3 cycles of Lu-PSMA, his blood count stabilized. He required no further BTs and his PSA level remained lowered.

Prostate-specific membrane antigen (PSMA) is highly expressed on prostate epithelial cells and strongly up-regulated in prostate cancer (PC), making it an optimal target for the treatment of metastasized PC. Radioligand therapy (RLT) with 177Lu-PSMA-DKFZ-617 (Lu-PSMA) is a targeted therapy for metastatic PC. In this study, we retrospectively analyzed the side effects and the response rate of 24 hormone and/or chemorefractory PC patients with a mean age of 75.2 years (range: 64-82) with distant metastases and progressive disease according to the PSA level, who were treated with Lu-PSMA. Median PSA was 522 ng/ml (range: 17-2360). Forty-six cycles of Lu-PSMA were performed. Of the 24 patients, 22 received two cycles. Eight weeks after the first cycle of Lu-PSMA therapy 79.1% experienced a decline in PSA level. Eight weeks after the second cycle of Lu-PSMA therapy 68.2% experienced a decline in PSA relative to the baseline value. Apart from two cases of grade 3 anemia, there was no relevant hemato- or nephrotoxicity (grade 3 or 4). These results confirmed that Lu-PSMA is a safe treatment option for metastatic PC patients and has a low toxicity profile. A positive response to therapy in terms of decline in PSA occurs in about 70% of patients.

Here we report on the preparation of well defined water-soluble poly(2-methyl-2-oxazoline) and poly(2-ethyl-2-oxazoline) terminally equipped with a chelator (N,N',N'',N'''-tetraazacylododecane-1,4,7,10-tetraacetic acid (DOTA)) for radionuclide labeling. The tissue distribution and excretion of (111)In-labeled poly(2-alkyl-2-oxazoline)s were studied in mice. We found that the hydrophilic polymers do not accumulate in tissues and are rapidly cleared from the blood pool, predominantly by glomerular filtration in the kidneys. In contrast only a small fraction is excreted via the hepatobiliary tract. Only minimal amounts of poly(2-alkyl-2-oxazoline)s are taken up by the reticuloendothelial system (RES). Scintigraphic studies revealed the feasibility of in vivo imaging of (111)In-labeled poly(2-oxazoline)s. Since additional functionalities for targeting can readily be introduced into poly(2-oxazoline)s via functional monomer units, these compounds fulfill fundamental requirements for an application as carrier molecules in radionuclide therapy.