[Therapy concepts for thyroid carcinoma]

Theranostics via the sodium iodide symporter (NIS) offer a unique option in differentiated thyroid carcinoma. The diagnostic and therapeutic nuclides have similar uptake and kinetics, making the NIS the most important theranostic target in this disease. Radioiodine refractory thyroid carcinomas (RRTC) are characterised by reduced/absent NIS expression, thus eliminating this structure as a theranostic target. Also due to limited therapeutic options, there are approaches to generate new theranostic targets in RRTC, via the expression of somatostatin receptors (SSTR) or the prostate-specific membrane antigen (PSMA), but the current evidence does not yet allow a final evaluation of the prospects of success.

[Therapy concepts for thyroid carcinoma]

Theranostics via the sodium iodide symporter (NIS) offer a unique option in differentiated thyroid carcinoma. The diagnostic and therapeutic nuclides have similar uptake and kinetics, making the NIS the most important theranostic target in this disease. Radioiodine refractory thyroid carcinomas (RRTC) are characterised by reduced/absent NIS expression, thus eliminating this structure as a theranostic target. Also due to limited therapeutic options, there are approaches to generate new theranostic targets in RRTC, via the expression of somatostatin receptors (SSTR) or the prostate-specific membrane antigen (PSMA), but the current evidence does not yet allow a final evaluation of the prospects of success.

[High clinical value of bone scintigraphy as a staging method for breast cancer]

BACKGROUND

Bone scintigraphy is a sensitive method for imaging bone metastases in patients with breast cancer. Despite its firm establishment in clinical routine, there are hardly any reliable data from larger homogeneous collectives on the value of bone scintigraphy in the context of staging of first diagnosed breast cancer patients.

AIM

The aim of our work was to evaluate the real-life performance of bone scintigraphy as a staging examination in female patients with the initial diagnosis of breast cancer.

PATIENTS AND METHODS

We retrospectively evaluated the data of the patients examined in the year 2015 with the first diagnosis of breast cancer at the University Hospital Marburg by bone scintigraphy. In addition a follow-up over a period of 30 months after the first bone scintigraphy was performed. For this purpose we evaluated whether the results of this initial diagnostic could be confirmed in following diagnostic.

RESULTS

207/258 patients showed no suspicious findings in the initial bone scintigraphy, 48 had an unclear finding, which is why 42 patients received further diagnostics. In follow-up, new bone metastases were found in 4 patients, all of these had scintigraphic findings in the primary diagnosis, which were considered "unclear". Depending on the evaluation of the event (suspicious for metastasis/suspicious for metastasis and unclear), the sensitivity was 37.5%/100%, the specificity 100%/80%, the positive predictive value 100%/15.7% and the negative predictive value 98%/100%.

CONCLUSION

By using bone scintigraphy and, if necessary, subsequent further imaging or histological clarification, a clinically significant diagnosis was obtained in 99,2% of the examined patients and confirmed in the follow-up. This result shows the good real-life performance of bone scintigraphy as a staging examination in patients with first diagnosed breast carcinomas.

Prostate-Specific Membrane Antigen in Anaplastic and Poorly Differentiated Thyroid Cancer-A New Diagnostic and Therapeutic Target?

Several studies have demonstrated an expression of the prostate-specific membrane antigen (PSMA) in the cancer-related neovasculature of thyroid malignancies. Due to the poor prognosis and limited therapeutic options for patients with anaplastic (ATC) and poorly differentiated (PDTC) thyroid carcinoma, the aim of our study was to investigate the theranostic approach of PSMA expression in these patients. The PSMA uptake on Gallium-68 (⁶⁸Ga)-PSMA-positron emission tomography/computed tomography (PET/CT) and glucose uptake on F-18-Fluordeoxyglucose (¹⁸F-FDG)-PET/CTs were analysed in two ATC and six PDTC patients. The PSMA expression in corresponding patients' tissue samples was detected by immunohistochemistry. In addition, various tissue sections from 22 ATC and six PDTC patients were examined concerning PSMA expression. ⁶⁸Ga-PSMA-PET/CT showed heterogeneous PSMA expression among patients and lesions. Six of the eight analyzed patients (two ATC, four PDTC) showed increased glucose metabolism without increased PSMA uptake after PET/CT. In one patient (PDTC), ¹⁸F-FDG-PET/CT tracer uptake was positive and ⁶⁸Ga-PSMA-PET/CT showed heterogeneous results. Another patient (PDTC) evidenced only PSMA-positive lesions and received two cycles of Lutetium-177 (¹⁷⁷Lu)-PSMA therapy, which kept his disease stable for seven months. There was a correlation between immunohistochemical PSMA expression and uptake on ⁶⁸Ga-PMSA-PET/CT in three of the examined patients. Twenty-seven of the analyzed 39 ATC and 13 of the analyzed 22 PDTC tissue sections showed a strong PSMA expression. Considering the rarity of PDTC and ATC, which is the reason for the small patient population we studied, the findings of this study confirm the high diagnostic sensitivity and superiority of ¹⁸F-FDG-PET/CT in comparison to ⁶⁸Ga-PSMA-PET/CT in the diagnosis of ATC and PDTC. However, it can be suggested that ⁶⁸Ga-PMSA-PET/CT can be considered as a beneficial adjunct to the well-established ¹⁸F-FDG-PET/CT for a few individual selected patients with ATC and PDTC to detect lesions not discovered by ¹⁸F-FDG-PET/CT and to determine patients' eligibility for a radioligand therapy. Radiolabelled PSMA-ligands may, in the future, represent a theranostic approach with only minor side effects for a few individual selected patients with ATC and PDTC who need alternative treatment options in case of progression when established therapies are no longer effective. However, due to the small sample size of our collective, larger studies are needed to allow for a final evaluation on the significance of PSMA-targeted diagnostic and therapy for ATC and PDTC.

DNA damage and repair in peripheral blood mononuclear cells after internal ex vivo irradiation of patient blood with 131I

Aim

The aim of this study was to provide a systematic approach to characterize DNA damage induction and repair in isolated peripheral blood mononuclear cells (PBMCs) after internal ex vivo irradiation with [¹³¹I]NaI. In this approach, we tried to mimic ex vivo the irradiation of patient blood in the first hours after radioiodine therapy.

Material and methods

Blood of 33 patients of two centres was collected immediately before radioiodine therapy of differentiated thyroid cancer (DTC) and split into two samples. One sample served as non-irradiated control. The second sample was exposed to ionizing radiation by adding 1 ml of [¹³¹I]NaI solution to 7 ml of blood, followed by incubation at 37 °C for 1 h. PBMCs of both samples were isolated, split in three parts each and (i) fixed in 70% ethanol and stored at − 20 °C directly (0 h) after irradiation, (ii) after 4 h and (iii) 24 h after irradiation and culture in RPMI medium. After immunofluorescence staining microscopically visible co-localizing γ-H2AX + 53BP1 foci were scored in 100 cells per sample as biomarkers for radiation-induced double-strand breaks (DSBs).

Results

Thirty-two of 33 blood samples could be analysed. The mean absorbed dose to the blood in all irradiated samples was 50.1 ± 2.3 mGy. For all time points (0 h, 4 h, 24 h), the average number of γ-H2AX + 53BP1 foci per cell was significantly different when compared to baseline and the other time points. The average number of radiation-induced foci (RIF) per cell after irradiation was 0.72 ± 0.16 at t = 0 h, 0.26 ± 0.09 at t = 4 h and 0.04 ± 0.09 at t = 24 h. A monoexponential fit of the mean values of the three time points provided a decay rate of 0.25 ± 0.05 h⁻¹, which is in good agreement with data obtained from external irradiation with γ- or X-rays.

Conclusion

This study provides novel data about the ex vivo DSB repair in internally irradiated PBMCs of patients before radionuclide therapy. Our findings show, in a large patient sample, that efficient repair occurs after internal irradiation with 50 mGy absorbed dose, and that the induction and repair rate after ¹³¹I exposure is comparable to that of external irradiation with γ- or X-rays.

Real-World Efficacy and Safety of Multi-Tyrosine Kinase Inhibitors in Radioiodine Refractory Thyroid Cancer

Background: The management of patients with locally advanced or metastatic differentiated thyroid cancer (DTC) that is refractory to radioiodine (RAI) remains a therapeutic challenge. The multi-tyrosine kinase inhibitors (TKIs) sorafenib and lenvatinib have been approved based on phase 3 clinical trials. Patients and Methods: We aimed at describing the efficacy and safety of TKI treatment of RAI-refractory DTC in a real-world setting at six German referral centers. One hundred and one patients with locally advanced or metastatic RAI-refractory DTC treated with sorafenib, lenvatinib, and/or pazopanib were included. Progression-free survival (PFS) and overall survival (OS) probabilities were estimated by using the Kaplan-Meier method. Results: Ninety-seven of 101 patients had progressive disease before TKI initiation. The median PFS for first-line treatment with sorafenib (n = 33), lenvatinib (n = 53), and pazopanib (n = 15) was 9 (95% confidence interval 5.2-12.8), 12 (4.4-19.6), and 12 months (4.4-19.6), respectively. The median OS for first-line treatment was 37 (10-64) for sorafenib, 47 (15.5-78.5) for lenvatinib, and 34 months (20.2-47.8) for pazopanib. Serious complications (e.g., hemorrhage, acute coronary syndrome, and thrombosis/venous thromboembolism) occurred in 16 out of 75 (21%) patients taking lenvatinib, in 3 out of 42 (7%) patients taking sorafenib, and in 3 out of 24 (13%) patients taking pazopanib. Conclusions: Sorafenib, lenvatinib, and pazopanib are effective treatment options in the majority of patients with RAI-refractory DTC. The PFS and six-month survival rate in patients treated with lenvatinib und pazopanib appear to compare favorably with sorafenib in the first-line treatment setting. However, a more advanced disease stage at treatment initiation in sorafenib- and pazopanib-treated patients in the era before TKI-approval and the retrospective nature of this study precludes a direct comparison of TKIs.

Theranostics in Thyroid Cancer

The main targeting structure for theranostics in thyroid cancer is the sodium-iodine symporter (NIS), which has been used in clinical routine for the diagnosis and treatment of thyroid diseases for more than 70 years. Because the different iodine (I) nuclides (¹²³I, ¹²⁴I, ¹³¹I) have the same kinetics, uniquely congruent theranostics are possible in differentiated thyroid cancer. Besides the NIS, there are further possibilities by using expression of somatostatin receptors or the expression of the prostate-specific membrane antigen, for example, in radioiodine-refractory differentiated thyroid cancer, medullary thyroid cancer, or anaplastic thyroid cancer.

Effect of Kinase Inhibitors on the Technetium-99m Uptake into Thyroid Carcinoma Cells In Vitro

BACKGROUND/AIM

We evaluated the potential of the kinase inhibitors sorafenib, lenvatinib and selumetinib on increasing the uptake of technetium-99m into thyroid cancer cells.

MATERIALS AND METHODS

Four established cell lines and three patient's cell cultures were treated with 0.1, 1 and 5 μM of sorafenib, lenvatinib and selumetinib for 72 hours. After incubation with 1 MBq of technetium-99m, the radioactivity uptake was measured.

RESULTS

The experiments showed heterogeneous results. Maximum technetium-99m uptake increases of 312% (sorafenib), 326% (lenvatinib) and 759% (selumetinib) were obtained using the highest applied concentrations. In some tests, an uptake reduction or no effect was observed.

CONCLUSION

Kinase inhibitors have a positive effect on technetium-99m uptake. Due to study limitations, a redifferentiating effect of the drugs could not be definitely proven. Unspecific cytotoxicity might have a confounding effect.

Perioperative diagnostics of patients referred for radioiodine therapy of differentiated thyroid carcinoma: referral center experience in an iodine-insufficient country

PURPOSE

The interdisciplinary "Martinique-Principles" of four international professional societies concerned with the patient management of differentiated thyroid cancer (DTC) patients were agreed upon. Differences in perioperative diagnostics can lead to differences in clinical decision founding regarding the treatment of thyroid carcinoma. Our aim was to analyze the perioperative diagnostics of patients referred for postoperative I-131 therapy of DTC.

METHODS

We retrospectively examined the data of 142 patients who were referred to our center for the first course of postsurgical I-131 therapy. We extracted data on perioperative diagnostics.

RESULTS

Fine-needle biopsy (FNB) was performed in 27/142 patients. In 17 patients, FNB yielded findings suspicious of malignancy, in 3 patients a follicular lesion was reported. An intraoperative frozen section analysis was performed in 79/142 patients. 5/63 patients showed already a cytologically proven malignancy. In 10/79 patients, the frozen section had a nonmalignant result, although DTC was found on final assessment. In 2/79 patients, frozen section analysis was indecisive, although the final report confirmed DTC. In the remaining 67 patients, frozen section yielded DTC.

CONCLUSIONS

There is room for improvement in perioperative diagnostics surrounding thyroid surgery, currently many procedures are performed without adequate information on potential presence of thyroid cancer. More frequent use of FNB might be able to decrease the number of unnecessary thyroid surgeries, increased use of frozen section might decrease the number of second operations and might contribute to less discordance between experts in the field of DTC treatment.

Reference values for quantitative parameters in renal scintigraphy with Tc-99m-MAG3

Background Reference values are the basis for an increase of standardisation and examiner independence, and thus an improvement in the inter-institutional comparability. However for renal Mercaptoacetyltriglycin (MAG3)-scintigraphy the establishment of such values however did not find its way into clinical routine despite the convincing advantages.

Aim The aim was to establish reference values for the decisive quantitative parameters of MAG3 renal scintigraphy. The reference values should help to significantly improve and facilitate the interpretation of the examination results in everyday clinical practice.

Methods We retrospectively evaluated all MAG3 renal scintigraphies performed in the Department of Nuclear Medicine, University Hospital Marburg between 01/2014 and 08/2017. The total sample of non-pathological renal scintigrafies included 247 patients aged between 25 days and 88 years. All investigtions were performed according to the present guidelines of the German Association for Nuclear Medicine. We analysed the ratio from pulse count rate after 20 minutes/Time (T) max and the Tmax separately.

Results Reference values for the Tmax and 20 min/T(max) count ratio of the MAG3 renal scintigraphy were defined for all adults over 18 years and divided by age catogories. For children aged 0–0.5 years and 0.5–2 years reference values for Tmax were defined.

Conclusion The results show a high degree of consistency with the reference values screened out in previous studies. This underlines the reliability of the reference values as a diagnostic tool in clinical application. The defined values are clinically feasible and promise a simplified and improved interpretation of the MAG3 renal scintigraphy.

[Follow-up of differentiated thyroid cancer]

The management of differentiated thyroid carcinoma has shown considerable changes in recent years, moving away from a fixed therapy regimen towards individual treatment strategies. The aim of our work (literature research) is to present current developments in the follow-up of differentiated thyroid cancer.For the management of individual follow-up, an initial evaluation and, at later time points, the re-evaluation of the risk of recurrence is crucial. The performance of I-131-diagnostics after radioiodine therapy can provide essential information and can be seen as a survey of a new baseline situation, in order to be able to draw a comparison in case of a rising Thyreoglobulin (Tg).The measurement of Tg with a highly sensitive assays shows a high negative predictive value. Negative Tg measurements with these assays seem to indicate complete remission even with Tg antibodies being present. An increasing Tg value in follow-up implies further diagnostic work-up, primarily neck ultrasonography. Sonographically suspicious findings should be subjected to fine needle biopsy, whereby in addition to cytological processing, determination of Tg from the sample can be recommended. If the suspicious lesion cannot be displayed sonographically and Tg values keep rising, computed tomography (CT) and magnetic resonance imaging (MRI) of the neck region can provide further information. FDG-PET/CT has also shown an excellent performance in this setting.The previously fixed therapy regimen has been realigned towards an individual treatment management. Current studies and guidelines lead to a repetitive recurrence risk evaluation and the adjustment of the aftercare planning to the individual risks with appropriately selected examination methods and personalized intervals of assessment.

Rhombencephalitis associated with isolated Zic4-antibodies in Paraneoplastic cerebellar degeneration: a case report

Background

Cerebellar degeneration as a consequence of a malignancy is a rare condition most commonly related to the presence of anti-Yo, anti-Hu, and anti-Tr/DNER antibodies. In recent years, several reports have indicated Zinc-finger protein 4 (Zic4) antibodies being associated with paraneoplastic cerebellar degeneration (PCD) in patients with small cell lung carcinoma. However, the prevalence and the significance of Zic4-antibodies may be underestimated due to their co-occurrence with more frequent antibodies such as anti-Hu. A literature review of isolated Zic4 mediated paraneoplastic syndromes yielded 14 cases reporting mainly benign clinical courses when treated early.

Case presentation

We present the case of a 67-year-old woman with progressive Zic4 antibody mediated PCD and rhombencephalitis. Immunomodulatory treatment, including intravenous methylprednisolone, plasmaphereses, and intravenous immunoglobulin (IVIG) was administered. Small cell lung cancer (SCLC) was detected, lobectomy performed and cyclophosphamide started. Despite this considerable therapeutic effort, rhombencephalitis led to defiant dysautonomia.

Conclusion

Paraneoplastic syndromes related to isolated Zic4 antibodies are rare and typically show a benign clinical course. Here, we present the first case of a rapidly progressive isolated Zic4 associated PCD and rhombencephalitis. Despite considerable therapeutic efforts, the patient passed away on autonomic dysfunction, highlighting the significance of Zic4 associated disease.

Score-based improvement of the indication for surgical treatment of thyroid lesions

BACKGROUND

 The prevalence of focal lesions in the thyroid is high in Germany. In 2018 about 70 000 thyroid surgeries were performed, although the malignancy rate of such findings is low. For this reason it is important to conduct an adequate selection of patients for whom surgery is indicated.

AIM

 The aim of our work was to validate the preoperative indication for surgery of thyroid lesions based on an independent, self-developed clinical score.

PATIENTS AND METHODS

 The patient data were evaluated retrospectively over the period 2013 to 2014. A prerequisite for inclusion was that the patients had carried out their complete treatment in domo. The multiparametic score was determined retrospectively and ranges from 3 to 15. The subjective improvement of symptoms (self-disclosure > 6 months postoperatively) and the presence of malignant histology were evaluated as positive outcome parameters.

RESULTS

 From a collective of 180 patients, 36 patients could be included, in whom all score-relevant parameters had been surveyed. The score distribution was 10 % score 3, 12.5 % score 4, 25 % score 5, 25 % score 6, 12.5 % score 7, 7.5 % score 8, 5 % score 9 and 2.5 % score 10. Using ROC analysis shows an AUC of 0.903, which is a very good differentiation. With a CUT-off score of 7 or higher, 86 % of patients have benefited from surgery.

CONCLUSION

 Our score with the parameters clinical complaints, sonographically defined size of the thyroid and the cytological result of a fine needle biopsy can lead to an improvement of the indication for surgical treatment of thyroid nodules.

Decrease of 99mTc-uptake in autonomous thyroid tissue in Germany since the 1970s

Aim: The clinical relevance of thyroidal autonomy, i.e. the risk of a patient to become hyperthyroid after exposure to iodine, can be estimated by measurement of the thyroidal 99mTc uptake under suppression of TSH (TcTUs). The upper tolerable limit has been set to 2% some 25 years ago. Considering the increase in nutritional iodine uptake over the last 15 years, we wanted to find out if the TcTUs per ml of autonomous volume may have changed. Patients, methods: We performed a pilot study in 1166 randomly chosen patients from 1980-2003 with different kinds of benign thyroid disorders to determine changes in TcTU or TcTUs over time. A second analysis was performed in 1063 patients from 1987-2004 with unifocal autonomy (UFA). In these patients, the volume of the autonomous tissue can be determined precisely thus allowing for exact determination of TcTUs per ml of autonomous volume. Results: The pilot study demonstrated that the TcTUs or the TcTU has been falling over the last 25 years in all benign thyroid disorders (p <0.01). The total thyroid volume has also been decreasing in all disorders. In the second analysis of UFA only, 500 from the 1063 patients fulfilled the inclusion criteria. In these patients, the TcTUs per ml of autonomous volume has fallen from an average of 0.48% to an average of 0.28%. These results are statistically significant as determined by ANOVA testing (p = 0.032). Conclusion: As the TcTUs in relation to autonomous volume has dropped by approximately 40% over the last 25 years, the upper limit for a normal TcTUs should be reduced to 1-1.4%, dependent on regional factors.

What is the best pre-therapeutic dosimetry for successful radioiodine therapy of multifocal autonomy?

Purpose: Dose calculation for radioiodine therapy (RIT) of multifocal autonomies (MFA) is a problem as therapeutic outcome may be worse than in other kinds of autonomies. We compared different dosimetric concepts in our patients. Patients, methods: Data from 187 patients who had undergone RIT for MFA (Marinelli algorithm, volumetric compromise) were included in the study. For calculation, either a standard or a measured half-life had been used and the dosimetric compromise (150 Gy, total thyroid volume). Therapeutic activities were calculated by 2 alternative concepts and compared to therapeutic success achieved (concept of TcTUs-based calculation of autonomous volume with 300 Gy and TcTUs-based adaptation of target dose on total thyroid volume). Results: If a standard half-life is used, therapeutic success was achieved in 90.2%(hypothyroidism 23,1%, n=143). If a measured half-life was used the success rate was 93.1% (13,6% hypothyroidism, n=44). These differences were statistically not significant, neither for all patients together nor for subgroups eu-, hypo-, or hyperthyroid after therapy (ANOVA, all p>0.05). The alternative dosimetric concepts would have resulted either in significantly lower organ doses (TcTUs-based calculation of autonomous volume; 80.76±80.6 Gy versus 125.6±46.3 Gy; p<0.0001) or in systematic over-treatment with significantly higher doses (TcTUs-adapted concept; 164.2±101.7 Gy versus 125.6±46.3 Gy; p=0.0097). Conclusions: TcTUsbased determination of the autonomous volume should not be performed, the TcTUs-based adaptation of the target dose will only increase the rate of hypothyroidism. A standard half-life may be used in pre-therapeutic dosimetry for RIT of MFA. If so, individual therapeutic activities may be calculated based on thyroid size corrected to the 24h ITUs without using Marinelli’s algorithm.

Therapie mit 177Lu-PSMA-617, Dosimetrie und Nachsorge beim metastasierten kastrationsresistenten Prostatakarzinom

Eine Radioligandentherapie (RLT) mit Lutetium-177 markierten Inhibitoren des Prostataspezifischen Membranantigens (177Lu-PSMA) erfolgt bei Patienten mit metastasiertem kastrationsrefraktären Prostatakarzinom (mCRPC) und fehlender Therapiealternative. Die RLT wird an deutschen Universitätsklinika seit 2013 im Rahmen der Ausübung der ärztlichen Heilkunde angeboten. Diese Konsensusempfehlung gibt Orientierung für die Durchführung einer RLT mit 177Lu-PSMA-617. Sie wurde im Rahmen einer Expertenrunde der Deutschen Gesellschaft für Nuklearmedizin (DGN) im Dezember 2015 erarbeitet und enthält Empfehlungen zu Indikationsstellung, Voruntersuchung, Therapieablauf, Begleittherapie, Dosimetrie und Nachsorge. Die Konsensusempfehlung dient der Information des beteiligten medizinischen Personals und zielt auf eine Harmonisierung der Therapieabläufe sowie eine Verbesserung der Qualität der medizinischen Versorgung des einzelnen Patienten.

Safety and efficacy of 177lu-PSMA-617 radioligand therapy in patients with mCRPC: A multicenter study

155

Background: Prostate specific membrane antigen (PSMA) is a promising target for imaging and therapy of prostate cancer. Small cohorts trials have shown promising results for response and tolerability of 177Lu-PSMA-617 radioligand therapy (RLT) in patients with metastatic castration-resistant disease. The aim of this multicenter study was to investigate safety and efficacy of this new therapy in a large, multicenter cohort. Methods: Data of 145 patients with metastatic castration resistant prostate cancer treated with at least a single dose of 177Lu-PSMA-617 at 12 therapy centers in Germany (median age 73 years, range 43-88) were collected. Up to 4 therapy cycles (range of administered activity 2 – 8 GBq) were given. Toxicity was categorized by the common toxicity criteria for adverse events based on serial blood tests and the physician’s report. Biochemical response was defined by a PSA decline ≥ 50% from baseline. Results: 248 therapy cycles were performed. Data for biochemical response were available in 99 patients and data for physician-reported and lab-based toxicity in 145 and 121 patients. The median follow-up was 16 weeks (range 2-30 weeks). Nineteen patients died during the observation period. Grade 3 to 4 hematotoxicity occurred in 18 patients: 10%, 4% and 3% of the patients experienced anemia, thrombocytopenia and leukopenia, respectively. Xerostomia occurred in 8%. Overall biochemical response rate was 45% following all therapy cycles. Elevated alkaline phosphatase and presence of visceral metastases were negatively correlated and the total number of therapy cycles correlated positively with biochemical response. 22 of 31 patients with no PSA decline > 50% after the first cycle did not respond to the second therapy cycle. Conclusions: Radioligand therapy with 177Lu-PSMA-617 shows promising response rates and a low toxicity in extensively pretreated patients with prostate cancer. Future prospective trials have to evaluate the effect of RLT on survival and potentially be considered in earlier stages of prostate cancer.

German Multicenter Study Investigating 177Lu-PSMA-617 Radioligand Therapy in Advanced Prostate Cancer Patients

¹⁷⁷Lu-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 ¹⁷⁷Lu-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 ¹⁷⁷Lu-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 ¹⁷⁷Lu-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.

German Multicenter Study Investigating 177Lu-PSMA-617 Radioligand Therapy in Advanced Prostate Cancer Patients

¹⁷⁷Lu-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 ¹⁷⁷Lu-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 ¹⁷⁷Lu-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 ¹⁷⁷Lu-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.

[177Lu-PSMA-617 therapy, dosimetry and follow-up in patients with metastatic castration-resistant prostate cancer]

Radioligand therapy (RLT) using 177Lu labelled inhibitors of the prostate-specific membrane antigen (177Lu-PSMA) is performed in patients with metastatic castration-resistant prostate cancer (mCRPC) after exhaustion of other options. German University Clinics offer RLT since 2013 on a compassionate use basis. The present consensus document includes recommendations for RLT with 177Lu-PSMA-617. These consensus statements were developed by an expert panel formed by the German Society of Nuclear Medicine (DGN) in December 2015. Statements include recommendations for indication, baseline tests, therapy protocol, concomitant therapy, dosimetry, and follow-up. Consensus recommendations aim to inform the attending medical staff, standardize 177Lu-PSMA-617 RLT, and improve quality of individual patient care.

Safety and Efficacy of Botulinum Toxin to Preserve Gland Function after Radiotherapy in Patients with Head and Neck Cancer: A Prospective, Randomized, Placebo-Controlled, Double-Blinded Phase I Clinical Trial

This prospective, randomized, placebo-controlled, double-blinded phase I clinical trial investigates safety and efficacy of botulinum toxin (BoNT) to preserve gland function after radiotherapy in patients with head and neck cancer. Twelve patients with advanced head and neck cancer were injected with BoNT into the submandibular glands prior to primary radiochemotherapy. Six patients received BoNT/A and 6 patients BoNT/A and B, half of each subgroup into their left and the other half into their right gland. As an internal control, sodium chloride was injected into the respective contralateral gland (placebo). For the evaluation of the salivary gland function, technetium pertechnetate salivary gland scintigraphy was performed before and after the end of radiotherapy. BoNT/A and B were well tolerated. Analysis of the scintigraphic data revealed no statistically significant difference between BoNT and placebo regarding the scintigraphic uptake difference (pBoNT/A = 0.84 and pBoNT/A-B = 0.56 for BoNT/A vs. placebo and BoNT/A-B vs. placebo, respectively). We also found no significant difference in treatment between BoNT and placebo in terms of salivary excretion fraction (pBoNT/A = 0.44; pBoNT/A-B = 0.44). This study demonstrates that BoNT can be safely combined with radiochemotherapy. Dosing and timing of BoNT injection should be further investigated for efficacy analysis.

Individualized multimodal treatment strategy for anaplastic thyroid carcinoma-Case report of long-term remission and review of literature

INTRODUCTION

The prognosis of anaplastic thyroid cancer (ATC) is poor with a mean survival time of six months following diagnosis. Despite various attempts to modify common treatment modalities including surgery, external beam radiation and chemotherapy, an effective treatment is not available yet. We report, here, a patient who achieved long-term survival based on multimodal treatment, including in vitro evaluation of drug response of his tumor cells.

PRESENTATION OF CASE

A 42 years old male patient underwent total thyroidectomy with central and lateral neck dissection for ATC (pT4b, pN0 (0/36), L0, V0, Pn1, R0 cM0 - UICC-Stage: IV b). From the tumor tissue a primary cell culture was established. While the patient received a combined radio-chemotherapy cell viability assays were performed using Sorafenib, Vandetanib und MLN8054 (Aurora kinase inhibitor) as inhibitors. Cell viability was determined by MTT-assay after 72 and 144h of treatment.

DISCUSSION

All the three compounds affected cell viability in a time- and dose dependent manner. These effects were most pronounced by Sorafenib. Based on in vitro findings, the patient was treated daily with 400mg Sorafenib for 75days. 43 months after initial diagnosis, the patient had no evidence of disease as shown by MRI, CT and FDG-PET-CT imaging.

CONCLUSION

In the setting of multimodal treatment, in vitro drug evaluation of individual tumor cells of patients might be a promising tool to ameliorate the fatal prognosis of selected ATC patients.

Management of a metastasized high grade insulinoma (G3) with refractory hypoglycemia: case report and review of the literature

Insulinomas represent the most common functional neuroendocrine tumor of the pancreas. They are usually solitary, benign, well differentiated (G1/G2) and curable by surgery. We describe the case of a 45 year old male Caucasian with a unique malignant, metastasized pancreatic insulinoma (Ki 67 of 70%, G3). To control excessive insulin production emanating in refractory hypoglycemia and growth of the highly proliferating tumor a multimodal therapeutic approach including the consecutive use of tumor debulking surgery, chemotherapy, TACE, SIRT, PRRT as well as a drug therapy with diazoxide, somatostatin analogs and everolimus was employed. Chemotherapy with carboplatin/etoposide plus everolimus provided the longest normoglycemic period. After progress chemotherapy with dacarbazine had the most positive effect, while debulking approaches such as surgery and liver directed therapies, as well as PRRT were less efficient with only transient success.

Imaging of firefly luciferase activity under antiangiogenic therapy in a heat shock protein 70-transfected melanoma tumor model

We investigated the effect of targeted gene therapy on heat shock protein 70 (Hsp70) expression in a melanoma tumor model (M21). M21 cells transfected with a plasmid containing the firefly luciferase reporter gene (ffluc), whose expression is driven by the hsp70 (hspa1b) or the cytomegalovirus (CMV) promoter, were grown to a size of 600 mm3. Five animals in each group were intravenously treated with an Arg-Gly-Asp peptide-nanoparticle/Raf-1 kinase inhibitor protein [RGD-NP/RAF(-)] complex. Bioluminescence imaging (BLI) (IVIS, Xenogen, Alameda, CA) was performed at set time intervals. Western blot analysis of the HSP70 protein was simultaneously performed. The size of the treated M21 tumors was nearly constant (637.8 ± 33.4 mm3 vs 674.8 ± 34.4 mm3). BLI showed that if transcription was controlled by the CMV promoter, firefly luciferase activity decreased to 51.1% ± 8.3%. When transcription was controlled by the hsp70 promoter, the highest firefly luciferase activity (4.4 ± 0.3-fold) was observed after 24 hours. In accordance with BLI, Western blot analysis showed an increase in the level of HSP70, with the maximum detection 24 hours after the injection of the RGD-NP/RAF(-) complex. Targeted antiangiogenic therapy can induce luciferase activity where transcription is controlled by an hsp70 promoter and HSP70 protein in melanoma tumors.

[A 79-year-old man with B symptoms and jaw claudication]

A 79-year-old patient presented with weight loss, subfebrile body temperature and unclear jaw pain. After ruling out malignant and infectious causes, positron emission tomography-computed tomography (PET-CT) revealed markedly elevated glucose utilization of the large thoracic and upper limb arteries, suggesting systemic vasculitis. Color-coded duplex sonography confirmed thickening of the wall of the external carotid artery consistent with vasculitis. The patient was diagnosed with giant cell arteritis involving the large thoracic arteries and the upper limb arteries but without involvement of the superficial temporal artery. Based on the involvement of the external carotid artery, the jaw pain could be classified as jaw claudication. Clinical and laboratory remission was achieved with systemic glucocorticoids which could subsequently be tapered. The patient is well and asymptomatic 12 months after diagnosis and 2 months without steroids.

Does contrast-enhanced cervical ultrasonography improve preoperative localization results in patients with sporadic primary hyperparathyroidism?

OBJECTIVE

Pre-operative localization studies are inevitable in patients with primary hyperparathyroidism (pHPT), who are eligible for focused or minimally invasive parathyroidectomy (MIP). High-resolution ultrasonography (US) in combination with planar (99m)Tc-Sestamibi-scintigraphy (MIBI) and additional single-photon emission computed tomography (SPECT) are the standard procedures to localize enlarged parathyroid glands. Our aim was to evaluate the practicability and significance of contrast-enhanced ultrasonography (CEUS) in patients with pHPT.

MATERIALS AND METHODS

All investigations were performed at the University Hospital Marburg. Totally, 25 patients with biochemical proven pHPT underwent preoperative US, MIBI/SPECT, and CEUS. For CEUS, a suspension of phospholipid-stabilized sulfur-hexafluoride (SF6) microbubbles in combination with a special 12 MHz linear US probe was used. All patients were investigated by two sonographers, who did not get to view the findings noted by the other. Finally, surgery was performed and histopathological results were obtained from 24 patients.

RESULTS

In 17 (68%) patients, US and MIBI/SPECT already raised suspicion of parathyroid lesions and all suspected lesions were reassessed by CEUS. However, no additional information was obtained using CEUS. Especially in eight patients with negative or inconsistent US and MIBI/SPECT results, CEUS did not provide additional information regarding the site of the suspected parathyroid adenoma. Overall, no side effects were observed using CEUS. Surgical cure was achieved in all patients.

CONCLUSION

In this limited cohort of patients, no additional information could be obtained using the costly CEUS compared to results of US and MIBI/SPECT.

Intact versus Fragmented 99mTc-Monoclonal Antibody Imaging of Infection in Patients with Septically Loosened Total Knee Arthroplasty

OBJECTIVE: This prospective study compared the diagnostic accuracy of imaging using an intact murine antigranulocyte antibody 99mTc-besilesomab, and a murine antibody Fab' fragment 99mTc-sulesomab, in patients with suspected septically loosened total knee arthroplasty. METHODS: Images from 20 patients who underwent three-phase bone scintigraphy followed by imaging using 99mTc-besilesomab ( n = 10) or 99mTc-sulesomab ( n = 10) were evaluated and compared. Final diagnosis was determined by microbiological evaluation of aspirated synovial fluid, intraoperative samples through the clinical course, or by long-term follow-up. RESULTS: Prosthesis infection was shown in 18 patients. At 4 and 24 h after intravenous injection, absolute uptake of 99mTc-besilesomab was significantly higher than 99mTc-sulesomab in infected knee joints. Infected-to-healthy knee activity ratios were similar at 4 and 24 h for 99mTc-besilesomab and 99mTc-sulesomab. CONCLUSIONS: Both 99mTc-besilesomab and 99mTc-sulesomab had similar diagnostic accuracy for the detection of septic arthroplasty. If repeated use of immunoscintigraphy is needed for follow-up, 99mTc-sulesomab should be preferred over 99mTc-besilesomab since it is known to be well tolerated and without side effects or incompatibility reactions.

Successful selective internal radiotherapy (SIRT) in a patient with a malignant solid pseudopapillary pancreatic neoplasm (SPN)

Solid pseudopapillary neoplasms of the pancreas (SPNs, Gruber-Frantz-Tumor) are a rare entity representing 1-5% of all exocrine pancreatic tumors. The pseudocystic lesions preferentially affect young females <30 years, are mostly benign (∼90%) and normally present with unspecific symptoms. We describe the case of a 16-years-old Asian woman that was initially diagnosed with an SPN in the pancreatic head with mesenterial and hepatic metastases. After diagnosis, an extensive tumor resection was performed including pyloric-preserving pancreatic head resection followed by sequential resection of all hepatic metastases. After the patient was diagnosed with a hepatic recurrence and high intrahepatic tumor load, we chose a multimodal procedure and performed a selective internal radiotherapy (SIRT). Four years after SIRT and 10 years after initial diagnosis of metastatic SPN, the patient is in a good condition without any evidence for hepatic recurrence. This case represents a rare clinical course of a malignant and invasive SPN with an exceptionally long survival despite of high initial tumor burden. The selective internal radiotherapy is a suitable approach for inducing long-term remissions of the strongly vascularized liver metastases.

Scintigraphic assessment of salivary gland function in a rat model

BACKGROUND

Salivary gland dysfunction with xerostomia is a major clinical problem without a causal therapy in most cases. The development of an animal model for scintigraphic assessment of salivary gland function has great clinical relevance for the investigation of promising new diagnostic and therapeutic strategies for chronic salivary gland diseases. This study reports the first experiences with scintigraphic analyses of salivary gland function in a rat model.

MATERIALS AND METHODS

Anatomical and scintigraphic studies were performed for topographic differentiation of major salivary glands of Wistar rats. (⁹⁹m)technetium pertechnetate salivary gland scanning was performed, appropriate regions of interest were determined and the gland-to-background ratio was examined for the evaluation of salivary gland function.

RESULTS

The quantitative analysis of salivary gland scintigraphy revealed a reliable comparison of major salivary glands on both sides with the gland-to-background ratio ranging from 1.26 to 1.94 with an average of 1.51.

CONCLUSION

This model seems to be appropriate for functional studies in an experimental setting.

Nonviral siRNA delivery to the lung: investigation of PEG-PEI polyplexes and their in vivo performance

This study describes the physicobiological characterization of PEI- and PEG-PEI polyplexes containing partially 2'-OMe modified 25/27mer dicer substrate siRNAs (DsiRNAs) and their in vivo behavior regarding biodistribution and systemic bioavailability after pulmonary application as well as their ability to knock down gene expression in the lung. Biophysical characterization included circular dichroism of siRNA in polyplexes, condensation efficiency of polymers and in vitro stability. After in vivo application, biodistribution and kinetics of radiolabeled polyplexes were quantified and recorded over time in three-dimensional SPECT images and by end point scintillation counting. The influence on lung tissue and on the humoral and cellular immunosystem was investigated, and finally knockdown of endogenous gene expression in the lung was determined qualitatively. While all of the polymers used in our study were proven to effectively condense siRNA, stability of the complexes depended on the PEG grafting degree. Interestingly, PEI 25 kDa, which showed the least interaction with mucin or surfactant in vitro, performed poorly in vivo. Our nuclear imaging approach enabled us to follow biodistribution of the instilled nanocarriers over time and indicated that PEGylated nanocarriers are more suitable for lung application. While moderate proinflammatory effects were attributed to PEI25k-PEG(2k)(10) nanocarriers, none of the treatments caused histological abnormalities. Our preliminary in vivo knockdown experiment suggests that PEG-PEI/siRNA complexes are promising nanomedicines for pulmonary siRNA delivery. These results encouraged us to further investigate possible adverse effects and to quantify in vivo gene silencing in the lung after intratracheal instillation of PEG-PEI/siRNA complexes.

Stability of siRNA polyplexes from poly(ethylenimine) and poly(ethylenimine)-g-poly(ethylene glycol) under in vivo conditions: effects on pharmacokinetics and biodistribution measured by Fluorescence Fluctuation Spectroscopy and Single Photon Emission Computed Tomography (SPECT) imaging

In search of optimizing siRNA delivery systems for systemic application, one critical parameter remains their stability in blood circulation. In this study, we have traced pharmacokinetics and biodistribution of each component of siRNA polyplexes formed with polyethylenimine 25 kDa (PEI) or PEGylated PEIs by in vivo real-time gamma camera recording, SPECT imaging, and scintillation counting of blood samples and dissected organs. In vivo behavior of siRNA and polymers were compared and interpreted in the context of in vivo stability of the polyplexes which had been measured by fluorescence fluctuation spectroscopy (FFS). Both pharmacokinetics and biodistribution of polymer-complexed siRNA were dominated by the polymer. PEGylated polymers and their siRNA polyplexes showed significantly less uptake into liver (13.6-19.7% ID of PEGylated polymer and 9.5-10.2% ID of siRNA) and spleen compared to PEI 25 kDa (liver deposition: 36.2% ID of polymer and 14.6% ID of siRNA). With non-invasive imaging methods we were able to predict both kinetics and deposition in living animals allowing the investigation of organ distribution in real time and at different time points. FFS measurements proved stability of the applied polyplexes under in vivo conditions which explained the different behavior of complexed from free siRNA. Despite their stability in circulation, we observed that polyplexes dissociated upon liver passage. Therefore, siRNA/(PEG-)PEI delivery systems are not suitable for systemic administration, but instead may be useful when the first-pass effect is circumvented, which is the case in local application.

(99m)Tc-Fab' fragments (sulesomab) for imaging septically loosened total knee arthroplasty

The diagnostic accuracy of infection scintigraphy with (99m)Tc-labelled monoclonal antibody Fab' fragments (sulesomab) was studied in patients with suspected total knee arthroplasty (TKA) infection. Images from 26 patients were evaluated by two independent readers and compared with a quantitative interpretation of time-activity courses. Microbiological examinations and joint aspiration results were used as reference standards. Histologically, aseptic TKA loosening occurred in two patients and severe, moderate or mild septic loosening in four, nine and 11 patients, respectively. Diagnostic accuracy for severe infection was 100% for both readers, whereas for moderate infection accuracy decreased by 12% and 12% for readers one and two, respectively. For mild infection a further decrease of approximately 61% and 52% occurred for readers one and two, respectively. Quantitative evaluation gave significantly better results over visual interpretation with a diagnostic accuracy of 100% for severe infection and decreased by only 10% and 15% in patients with moderate and mild infection, respectively. Quantitative evaluation of (99m)Tc-Fab' fragments is highly sensitive and specific for diagnostic imaging of infection in patients with septically-loosened TKA.

In vivo SPECT and real-time gamma camera imaging of biodistribution and pharmacokinetics of siRNA delivery using an optimized radiolabeling and purification procedure

Single photon emission computed tomography (SPECT) imaging provides a three-dimensional method for exactly locating gamma emitters in a noninvasive procedure under in vivo conditions. For characterization of siRNA delivery systems, molecular imaging techniques are extremely helpful to follow biodistribution under in experimental animal studies. Quantification of biodistribution of siRNA and nonviral delivery systems using this technique requires efficient methods to stably label siRNA with a gamma emitter (e.g., 111In or 99mTc) and to purify labeled material from excesses of radiolabel or linkers. In the following study, we have optimized labeling and purification of siRNA, which was then applied as free siRNA or after complexation with polyethylenimine (PEI) 25 kDa for in vivo real-time gamma camera and SPECT imaging. Quantification of scintillation counts in regions of interest(ROIs) was compared to conventional scintillation counting of dissected organs, and the data acquired by imaging was shown to corroborate that of scintillation counting. This optimization and proof of principle study demonstrates that biodistribution and pharmacokinetics of siRNA and the corresponding polyplexes can be determined using SPECT, leading to comparable results as conventional methodology.

Effectiveness and renal tolerance of multidetector helical CT with gadobutrol: results of a comparative porcine study

PURPOSE

To prospectively evaluate the safety and effectiveness of high doses of 1 mol/L gadobutrol as a contrast agent for computed tomography (CT).

MATERIALS AND METHODS

Experiments were performed according to guidelines for care of laboratory animals. The local animal care committee approved the study protocol. Unenhanced and contrast material-enhanced CT images of the chest and abdomen were obtained randomly in nine domestic pigs. Gadobutrol was injected (1, 2, or 3 mL per kilogram of body weight; three pigs for each dose). Attenuation was measured in different vascular and parenchymal structures. Changes in blood chemistry and hematologic parameters were monitored before and 1, 2, 3, and 7 days after gadobutrol administration. Urine samples were evaluated before and 7 days after gadobutrol administration. Technetium 99m mertiatide renal scintigraphy was performed before and 7 days after contrast medium injection. Animals were sacrificed 7 days after contrast medium administration, and one kidney was removed from each animal for examination with light microscopy. No serious adverse events occurred. A mixed-model nested analysis of variance was used for statistical evaluation.

RESULTS

Mean attenuations for the 1, 2, and 3 mL/kg gadobutrol doses, respectively, were 148 HU +/- 20 (standard deviation), 282 HU +/- 18, and 289 HU +/- 20 in the thoracic aorta; 99 HU +/- 11, 166 HU +/- 9, and 153 HU +/- 18 in the kidneys; and 106 HU +/- 7, 186 HU +/- 18, and 224 HU +/- 24 in the inferior vena cava. No clinically relevant changes in hematologic, blood chemistry, or urine analysis results were detected. Markers for glomerular filtration and tubular function were unaffected in all groups. Scintigraphy revealed no differences between unenhanced and contrast-enhanced results. No morphologic changes of the renal parenchyma were found at histologic analysis.

CONCLUSION

Contrast-enhanced CT with a 2 or 3 mmol/kg dose of 1 mol/L gadobutrol resulted in excellent vascular and parenchymal enhancement. A gadobutrol dose of up to 3 mL/kg did not affect renal function.

What is the best pre-therapeutic dosimetry for successful radioiodine therapy of multifocal autonomy?

PURPOSE

Dose calculation for radioiodine therapy (RIT) of multifocal autonomies (MFA) is a problem as therapeutic outcome may be worse than in other kinds of autonomies. We compared different dosimetric concepts in our patients.

PATIENTS, METHODS

Data from 187 patients who had undergone RIT for MFA (Marinelli algorithm, volumetric compromise) were included in the study. For calculation, either a standard or a measured half-life had been used and the dosimetric compromise (150 Gy, total thyroid volume). Therapeutic activities were calculated by 2 alternative concepts and compared to therapeutic success achieved (concept of TcTUs-based calculation of autonomous volume with 300 Gy and TcTUs-based adaptation of target dose on total thyroid volume).

RESULTS

If a standard half-life is used, therapeutic success was achieved in 90.2% (hypothyroidism 23,1%, n = 143). If a measured half-life was used the success rate was 93.1% (13,6% hypothyroidism, n = 44). These differences were statistically not significant, neither for all patients together nor for subgroups eu-, hypo-, or hyperthyroid after therapy (ANOVA, all p > 0.05). The alternative dosimetric concepts would have resulted either in significantly lower organ doses (TcTUs-based calculation of autonomous volume; 80.76 +/- 80.6 Gy versus 125.6 +/- 46.3 Gy; p < 0.0001) or in systematic over-treatment with significantly higher doses (TcTUs-adapted concept; 164.2 +/- 101.7 Gy versus 125.6 +/- 46.3 Gy; p = 0.0097).

CONCLUSIONS

TcTUsbased determination of the autonomous volume should not be performed, the TcTUs-based adaptation of the target dose will only increase the rate of hypothyroidism. A standard half-life may be used in pre-therapeutic dosimetry for RIT of MFA. If so, individual therapeutic activities may be calculated based on thyroid size corrected to the 24h ITUs without using Marinelli's algorithm.

Decrease of (99m)Tc-uptake in autonomous thyroid tissue in Germany since the 1970s. Clinical implications for radioiodine therapy

AIM

The clinical relevance of thyroidal autonomy, i.e. the risk of a patient to become hyperthyroid after exposure to iodine, can be estimated by measurement of the thyroidal (99m)Tc uptake under suppression of TSH (TcTUs). The upper tolerable limit has been set to 2% some 25 years ago. Considering the increase in nutritional iodine uptake over the last 15 years, we wanted to find out if the TcTUs per ml of autonomous volume may have changed.

PATIENTS, METHODS

We performed a pilot study in 1166 randomly chosen patients from 1980-2003 with different kinds of benign thyroid disorders to determine changes in TcTU or TcTUs over time. A second analysis was performed in 1063 patients from 1987-2004 with unifocal autonomy (UFA). In these patients, the volume of the autonomous tissue can be determined precisely thus allowing for exact determination of TcTUs per ml of autonomous volume.

RESULTS

The pilot study demonstrated that the TcTUs or the TcTU has been falling over the last 25 years in all benign thyroid disorders (p < 0.01). The total thyroid volume has also been decreasing in all disorders. In the second analysis of UFA only, 500 from the 1063 patients fulfilled the inclusion criteria. In these patients, the TcTUs per ml of autonomous volume has fallen from an average of 0.48% to an average of 0.28%. These results are statistically significant as determined by ANOVA testing (p = 0.032).

CONCLUSION

As the TcTUs in relation to autonomous volume has dropped by approximately 40% over the last 25 years, the upper limit for a normal TcTUs should be reduced to 1-1.4%, dependent on regional factors.

A novel somatostatin conjugate with a high affinity to all five somatostatin receptor subtypes

BACKGROUND

Somatostatin receptors (SRS, five subtypes) are expressed in a variety of human tumors, including most tumors of neuroendocrine origin, breast tumors, certain brain tumors, renal cell tumors, lymphomas, and prostate cancer. Somatostatin (SMS) triggers cytostatic and cytotoxic effects and has a general inhibitory effect on secretion mediated through its interaction with SRS. That is the basis for its use in the treatment of SRS-positive tumors. Radiolabeled SMS analogs can also be used for systemic radiotherapy and for diagnostic investigations.

METHODS

Sms-14 was conjugated to a periodate-activated dextran70 (mean molecular weight, 70 kD) by reductive amination. The human tumor cell line LCC-18, from a neuroendocrine colonic tumor, was used for stable transfection with each SRS gene separately; transfection was achieved with the expression system TETon (Clontech, Palo Alto, CA). Clones were selected by culturing with G418 and hygromycin B, and positive clones were identified by reverse transcriptase-polymerase chain reaction and binding of iodine-125-labeled SMS-14. The binding affinity for each SRS subtype was then determined for the SMS-dextran conjugate (with SMS-14 used as a positive control).

RESULTS

Sms-dextran70 showed high affinity binding to all five receptor subtypes. The IC50 values were between 3 and 80 nM.

CONCLUSIONS

This conjugate has a long circulation half-life (i.e., approximately 27 hours after subcutaneous administration in mice) and, with high SRS pan-affinity demonstrated in this study, it has potential in the therapy of SRS-positive tumors. Currently, the clinical significance of SMS-dextran70 is being explored in a clinical Phase I-II study of patients with hormone-refractory prostate cancer. The outcome of this study will be reported when it is available.