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Summary Aim: Besides the use of somatostatin analogues, small molecules like sunitinib and everolimus as well as conventional chemotherapy, peptide receptor radiotherapy (PRRT) using radiolabelled somatostatin analogues has gained an important role in the treatment of inoperable, metastasized neuroendocrine tumours (NET). There are various radiotracers in use. Based on our experience with the PET tracer [68Ga]DOTA-3-iodo- Tyr3-octreotate ([68Ga]HA-DOTATATE), a DOTATATE derivative with an increased binding affinity to hsst5, the current retrospective analysis is exploring the therapeutic potential of [177Lu]HA-DOTATATE. Methods: Eighteen patients with metastatic NET (G1/G2) were treated using [177Lu]DOTATATE and/or [177Lu]HA-DOTATATE, and dosimetric results of both tracers were compared. Results: Using [177Lu]HA-DOTATATE, a mean tumour dose of 5.34 Gy/GBq (median 2.53 Gy/ GBq; range 0.89-33.3 Gy/GBq) was achieved, while [177Lu]DOTATATE delivered a tumour dose of 5.53 Gy/GBq (median 2.70 Gy/GBq; range 0.44-15.3 Gy/GBq). Organ doses for [177Lu]HA-DOTATATE vs. [177Lu]DOTATATE were as follows: kidney 2.31 ± 0.85 vs. 2.03 ± 0.96 Gy/GBq, liver 1.6 ± 0.79 vs. 1.67 ± 1.73 Gy/GBq, spleen 3.89 ± 4.04 vs. 4.50 ± 3.69 Gy/GBq and whole body 0.16 ± 0.10 Gy/GBq vs. 0.15 ± 0.08 Gy/ GBq. Tumour-to-kidney dose ratio was slightly higher for [177Lu]DOTATATE (2.4 ± 5.6) compared to [177Lu]HA-DOTATATE (1.5 ± 3.6). Conclusion: Both tracers showed marked inter-patient variation in their dosimetry, and no significant differences in dosimetry of [177Lu]HA- DOTATATE and [177Lu]DOTATATE were observed when taking all patients into account. Thus, [177Lu]HA-DOTATATE appears viable for PRRT, although it was marginally inferior regarding kidney dose and tumour-to-kidney dose ratio compared to the established [177Lu]DOTATATE.

Ziel: In diesem Beitrag wird ein Uberblick uber den aktuellen Stand der radiopharmazeutischen Forschung in Bezug auf die Entwicklung von Radiopharmaka fur die Diagnostik und Therapie des Prostatakarzinoms (PCa) gegeben. Material und Methode: Hierzu wurden die jungsten Entwicklungen zusammengestellt und mit besonderem Augenmerk auf die klinische Anwendung am Patienten bewertet und kommentiert. Ergebnisse: Zahlreiche Radiopharmaka, die seit einiger Zeit fur die klinische Positronenemissionstomografie (PET) und Single-Photonen-Emissionstomografie (SPECT) Diagnostik des PCa eingesetzt werden, adressieren PCa-assoziierte metabolische Prozesse mit einer mehr oder minder ausgepragten Spezifitat. Beispiele fur diese Gruppe von Radiopharmaka sind [18F]Fluorid, [11C]Acetat, [18F]Fluoroethylcholin ([18F]FEC), [18F]Fluoromethylcholin ([18F]FMC) und [11C]Cholin. Einen neuen Tracer dieses Typs stellt die kunstliche Aminosaure anti-1-amino-3-[18F]fluorocyclobutan-1-carbonsaure ([18F]FACBC) dar. Hierneben werden vornehmlich spezifische Rezeptorliganden, wie 16β-[18F]fluoro-5α-dihydrotestosteron ([18F]FDHT), radiomarkierte GRPR-Liganden (Gastrin Releasing Peptide Rezeptor, BB2) und radiomarkierte Antikorper gegen das Prostata-spezifische Membranantigen (PSMA, NAALADase I oder Glutamat-Carboxypeptidase II) sowie PSMA-spezifische Inhibitoren untersucht. Fur die Therapie des PCa kommen in jungster Zeit PSMA-gerichtete Antikorper und Inhibitoren zum Einsatz, wahrend fur die Radionuklidtherapie ossarer Metastasen in 2014 [223Ra]RaCl2 (Xofigo) die FDA- und EMA-Zulassung erhielt. Schlussfolgerungen: Wahrend einige ‚metabolische’ Radiopharmaka nur masigen Erfolg in klinischen Studien zeigten, stehen mit den jungst entwickelten PSMA-Inhibitoren, PSMA-bindenden hohermolekularen Radiopharmaka (Antikorper und deren Fragmente) und GRPR-Liganden besonders aussichtsreiche neue Tracer-Klassen fur die Diagnostik und Radionuklidtherapie des PCa zur Verfugung. Trotz der bisher herausragenden Ergebnisse mit PSMA-Inhibitoren werden gros angelegte Vergleichsstudien eine vergleichende Bewertung mit GRPR-Liganden erlauben.

HISTORY AND CLINICAL FINDINGS A 39-year-old patient with advanced HIV infection was admitted to our hospital with a 6-month history of diarrhoea, abdominal pain and pansinusitis. INVESTIGATIONS Ultrasound and endoscopic retrograde cholangiography revealed cholangitis of the larger bile ducts. Stool examinations and coloscopy were unremarkable. No pathogenic organisms were identified by routine investigations. Finally, microsporidia of the genus encephalitozoon were diagnosed by electron microscopy in biopsies from the bile duct and the nasal mucous membrane and in stool samples by polymerase chain reaction (PCR). TREATMENT AND COURSE Albendazole treatment was successful. The cholestatic liver tests and the ultrasound findings normalized. Control tests of stool, bile and nasal secretions by light microscopy, electron microscopy, and PCR were negative. CONCLUSION Microsporidia, along with human cytomegalovirus, cryptosporida and mycobacteria other than tuberculosis are increasingly recognized as causing opportunistic infections in immunodeficient patients, especially in AIDS-related cholangitis. Some species can cause systemic infection. Therefore microsporidia infection should be considered in the differential diagnosis of all patients with immunodeficiency.

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