Automated light-induced synthesis of 89Zr-radiolabeled antibodies for immuno-positron emission tomography

Clinical production of 89Zr-radiolabeled antibodies (89Zr-mAbs) for positron emission tomography imaging relies on the pre-conjugation of desferrioxamine B (DFO) to the purified protein, followed by isolation and characterization of the functionalized intermediate, and then manual radiosynthesis. Although highly successful, this route exposes radiochemists to a potentially large radiation dose and entails several technological and economic hurdles that limit access of 89Zr-mAbs to just a specialist few Nuclear Medicine facilities worldwide. Here, we introduce a fully automated synthesis box that can produce individual doses of 89Zr-mAbs formulated in sterile solution in 99%, and chemical purity > 99%. The synthesis unit can also produce 89Zr-mAbs via the conventional radiolabeling routes from pre-functionalized DFO-mAbs that are currently used in the clinic. This automated method will improve access to state-of-the-art 89Zr-mAbs at the many Nuclear Medicine and research institutions that require automated devices for radiotracer production

Eine Methode zur effizienten und effektiven Unterstützung der kontinuierlichen Validierung im Kontext der PGE - Produktgenerationsentwicklung = A Method for an Efficient and Effective Support of Continuous Validation in the Context of PGE - Product Generation Engineering

In Zeiten immer komplexer werdender Produkte, die gleichzeitig häufig einen höchst multi-disziplinären Charakter aufweisen, wird es für die Produktentwickler immer schwieriger, die Funktionsweisen und Zusammenhänge der Systeme übergreifend und im Detail zu durchdringen. So lässt sich das Verhalten eines Teilsystems im Kontext des Übersystems im Verlauf der Entwicklung nur sehr schwer und mit hoher Unsicherheit voraussagen. Durch kontinuierliche Validierungsaktivitäten können die Produktentwickler diese Wissenslücken kompensieren und die Unsicherheit reduzieren. Jedoch sind die Produktentwicklungsprozesse aufgrund der immer kürzer werden Entwicklungszyklen einem großen Effizienzdruck unterworfen. Die Herausforderung ist dabei, dass eine Steigerung der Effizienz auch und vor allem der sehr aufwendigen Aktivität der Validierung nicht zu einem unverhältnismäßig ansteigenden Entwicklungsrisiko führen darf. In dieser Arbeit wird eine Methode zur Priorisierung von Validierungsaktivitäten entwickelt, die auf der Bestimmung der Kritikalität einzelner Teilsysteme / Funktionen basiert. Hierfür werden unterschiedliche Kriterien ermittelt und in geeigneter Weise zusammengeführt. Die Unsicherheit der Entwickler bzgl. der Funktionsweise einzelner Teilsysteme sowie die Auswirkungen einer notwendigen Änderung werden dabei berücksichtigt. Der auf diese Auswahl bzw. Priorisierung folgende Schritt der Definition der durchzuführenden Tests wird ebenfalls methodisch unterstützt. Hierbei kann keine konkrete und gleichzeitig allgemeingültige Herangehensweise definiert werden. Vielmehr wird in dieser Arbeit eine Methode entwickelt, die die Entwickler dabei unterstützt, die in den Unternehmen und einzelnen Abteilungen vorhandene Erfahrung bei der Testdefinition zielführend einzusetzen. Zu diesem Zweck wird ein Test-Beschreibungsmodell entwickelt, mit dem Tests beschrieben und dokumentiert werden können um daraus Referenzprozesse für die zukünftige Validierung abzuleiten

New tactics in the design of theranostic radiotracers

In the context of molecularly targeted radiotherapy, dosimetry concerns in off-target tissues are a major limitation to the more wide-spread application of radiopharmaceuticals to treat diseases like cancer. Reducing off-target accumulation of radionuclides in background tissues, whilst maintaining high and specific uptake in disease sites and improving the therapeutic window, requires rethinking common radiotracer design concepts. This article explores ways in which innovative radiotracer chemistry (the making and breaking of bonds) is used to modify interactions with the host organism to control excretion profiles and dosimetry at the tissue-specific level

Photoactivatable Fluorescent Tags for Dual-Modality Positron Emission Tomography Optical Imaging

Fluorescent protein conjugates are vital tools in a wide range of scientific disciplines from basic biochemical research to applications in clinical pathology and intraoperative surgery. We report the synthesis and characterization of photoactivatable fluorophores (PhotoTags) based on the functionalization of coumarin, fluorescein, BODIPY, rhodamine B, and cyanine dyes with a photochemically active aryl azide group. Photochemical labeling experiments using human serum albumin produced fluorescent proteins in high yields under irradiation with ultraviolet light for <15 min. We also synthesized DFO-RhodB-PEG3-ArN3─a photoactivatable compound that can be radiolabeled with 89Zr for applications in optical imaging and positron emission tomography. One-pot 89Zr-radiolabeling and light-induced protein conjugation produced [89Zr]ZrDFO-RhodB-PEG3-azepin-trastuzumab. Proof-of-concept studies in vitro and in vivo confirmed that [89Zr]ZrDFO-RhodB-PEG3-azepin-trastuzumab is a potential dual-modality agent for detecting human epidermal growth factor receptor 2 (HER2/neu) expression. Overall, the PhotoTag technology represents a rapid, synthetically versatile, and user-friendly approach for generating novel protein conjugates

Charting the Chemical and Mechanistic Scope of Light-Triggered Protein Ligation

The creation of discrete, covalent bonds between a protein and a functional molecule like a drug, fluorophore, or radiolabeled complex is essential for making state-of-the-art tools that find applications in basic science and clinical medicine. Photochemistry offers a unique set of reactive groups that hold potential for the synthesis of protein conjugates. Previous studies have demonstrated that photoactivatable desferrioxamine B (DFO) derivatives featuring a para-substituted aryl azide ($ArN_3$) can be used to produce viable zirconium-89-radiolabeled monoclonal antibodies ($^{89}Zr-mAbs$) for applications in noninvasive diagnostic positron emission tomography (PET) imaging of cancers. Here, we report on the synthesis, $^{89}Zr$-radiochemistry, and light-triggered photoradiosynthesis of $^{89}Zr$-labeled human serum albumin (HSA) using a series of 14 different photoactivatable DFO derivatives. The photoactive groups explore a range of substituted, and isomeric $ArN_3$ reagents, as well as derivatives of benzophenone, a para-substituted trifluoromethyl phenyl diazirine, and a tetrazole species. For the compounds studied, efficient photochemical activation occurs inside the UVA-to-visible region of the electromagnetic spectrum (∼365–450 nm) and the photochemical reactions with HSA in water were complete within 15 min under ambient conditions. Under standardized experimental conditions, photoradiosynthesis with compounds 1–14 produced the corresponding $^{89}ZrDFO-PEG_{3}-HSA$ conjugates with decay-corrected isolated radiochemical yields between 18.1 ± 1.8% and 62.3 ± 3.6%. Extensive density functional theory (DFT) calculations were used to explore the reaction mechanisms and chemoselectivity of the light-induced bimolecular conjugation of compounds 1–14 to protein. The photoactivatable DFO-derivatives operate by at least five distinct mechanisms, each producing a different type of bioconjugate bond. Overall, the experimental and computational work presented here confirms that photochemistry is a viable option for making diverse, functionalized protein conjugates

Boosting Efficiency in Light‐Driven Water Splitting by Dynamic Irradiation through Synchronizing Reaction and Transport Processes **

Abstract This work elaborates the effect of dynamic irradiation on light‐driven molecular water oxidation to counteract deactivation. It highlights the importance of overall reaction engineering to overcome limiting factors in artificial photosynthesis reactions. Systematic investigation of a homogeneous three‐component ruthenium‐based water oxidation system revealed significant potential to enhance the overall catalytic efficiency by synchronizing the timescales of photoreaction and mass transport in a capillary flow reactor. The overall activity could be improved by a factor of more than 10 with respect to the turnover number and a factor of 31 referring to the external energy efficiency by controlling the local availability of photons. Detailed insights into the mechanism of light driven water oxidation could be obtained using complementary methods of investigation like Raman, IR, and UV/Vis/emission spectroscopy, unraveling the importance of avoiding high concentrations of excited photosensitizers.Water splitting : Dynamic irradiation enables a significant increase in catalytic performance of a homogeneous three‐component system for light‐driven water oxidation. Lower irradiation intensities and higher flowrates in a flow‐through reactor minimize photosensitizer degradation and thus improve catalyst lifetime, yield, and overall efficiency of a catalytic system for artificial photosynthesis. imag

NELF Potentiates Gene Transcription in the Drosophila Embryo

A hallmark of genes that are subject to developmental regulation of transcriptional elongation is association of the negative elongation factor NELF with the paused RNA polymerase complex. Here we use a combination of biochemical and genetic experiments to investigate the in vivo function of NELF in the Drosophila embryo. NELF associates with different gene promoter regions in correlation with the association of RNA polymerase II (Pol II) and the initial activation of gene expression during the early stages of embryogenesis. Genetic experiments reveal that maternally provided NELF is required for the activation, rather than the repression of reporter genes that emulate the expression of key developmental control genes. Furthermore, the relative requirement for NELF is dictated by attributes of the flanking cis-regulatory information. We propose that NELF-associated paused Pol II complexes provide a platform for high fidelity integration of the combinatorial spatial and temporal information that is central to the regulation of gene expression during animal development