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Contains fulltext : 305358.pdf (Publisher’s version ) (Closed access), Antibodies that block immune checkpoints, also called immune checkpoint inhibitors (ICI), have demonstrated impressive anti-tumor efficacy. The success of ICIs results from a complex interplay between cancer cells and their immune microenvironment. One of the predictors for ICI efficacy is the expression of the targeted immune checkpoint, such as programmed death ligand 1 (PD-L1). Immune checkpoints can be expressed on tumor cells and/or subsets of immune cells. PET imaging offers unique possibilities to study the dynamics of immune checkpoint expression in tumor and normal tissues in a longitudinal manner. In this chapter, we describe the methodology to use zirconium-89-labeled antibodies to assess the expression of immune checkpoint molecules in syngeneic murine tumor models by PET imaging.

Item does not contain fulltext, PURPOSE: Watchful waiting (WW) can be considered for patients with metastatic clear-cell renal cell carcinoma (mccRCC) with good or intermediate prognosis, especially those with <2 International Metastatic RCC Database Consortium criteria and ≤2 metastatic sites [referred to as watch and wait ("W&W") criteria]. The IMaging PAtients for Cancer drug SelecTion-Renal Cell Carcinoma study objective was to assess the predictive value of [18F]FDG PET/CT and [89Zr]Zr-DFO-girentuximab PET/CT for WW duration in patients with mccRCC. EXPERIMENTAL DESIGN: Between February 2015 and March 2018, 48 patients were enrolled, including 40 evaluable patients with good (n = 14) and intermediate (n = 26) prognosis. Baseline contrast-enhanced CT, [18F]FDG and [89Zr]Zr-DFO-girentuximab PET/CT were performed. Primary endpoint was the time to disease progression warranting systemic treatment. Maximum standardized uptake values (SUVmax) were measured using lesions on CT images coregistered to PET/CT. High and low uptake groups were defined on the basis of median geometric mean SUVmax of RECIST-measurable lesions across patients. RESULTS: The median WW time was 16.1 months [95% confidence interval (CI): 9.0-31.7]. The median WW period was shorter in patients with high [18F]FDG tumor uptake than those with low uptake (9.0 vs. 36.2 months; HR, 5.6; 95% CI: 2.4-14.7; P < 0.001). Patients with high [89Zr]Zr-DFO-girentuximab tumor uptake had a median WW period of 9.3 versus 21.3 months with low uptake (HR, 1.7; 95% CI: 0.9-3.3; P = 0.13). Patients with "W&W criteria" had a longer median WW period of 21.3 compared with patients without: 9.3 months (HR, 1.9; 95% CI: 0.9-3.9; Pone-sided = 0.034). Adding [18F]FDG uptake to the "W&W criteria" improved the prediction of WW duration (P < 0.001); whereas [89Zr]Zr-DFO-girentuximab did not (P = 0.53). CONCLUSIONS: In patients with good- or intermediate-risk mccRCC, low [18F]FDG uptake is associated with prolonged WW. This study shows the predictive value of

01 juni 2023, Item does not contain fulltext, INTRODUCTION: Fibroblast activation protein (FAP) is highly overexpressed in stromal tissue of various cancers. While FAP has been recognized as a potential diagnostic or therapeutic cancer target for decades, the surge of radiolabeled FAP-targeting molecules has the potential to revolutionize its perspective. It is presently hypothesized that FAP targeted radioligand therapy (TRT) may become a novel treatment for various types of cancer. To date, several preclinical and case series have been reported on FAP TRT using varying compounds and showing effective and tolerant results in advanced cancer patients. Here, we review the current (pre)clinical data on FAP TRT and discuss its perspective towards broader clinical implementation. METHODS: A PubMed search was performed to identify all FAP tracers used for TRT. Both preclinical and clinical studies were included if they reported on dosimetry, treatment response or adverse events. The last search was performed on July 22 2022. In addition, a database search was performed on clinical trial registries (date 15(th) of July 2022) to search for prospective trials on FAP TRT. RESULTS: In total, 35 papers were identified that were related to FAP TRT. This resulted in the inclusion of the following tracers for review: FAPI-04, FAPI-46, FAP-2286, SA.FAP, ND-bisFAPI, PNT6555, TEFAPI-06/07, FAPI-C12/C16, and FSDD. CONCLUSION: To date, data was reported on more than 100 patients that were treated with different FAP targeted radionuclide therapies such as [(177)Lu]Lu-FAPI-04, [(90)Y]Y-FAPI-46, [(177)Lu]Lu-FAP-2286, [(177)Lu]Lu-DOTA.SA.FAPI and [(177)Lu]Lu-DOTAGA.(SA.FAPi)(2). In these studies, FAP targeted radionuclide therapy has resulted in objective responses in difficult to treat end stage cancer patients with manageable adverse events. Although no prospective data is yet available, these early data encourages further research.

Item does not contain fulltext, Positron emission tomography (PET) imaging is used in drug development to noninvasively measure biodistribution and receptor occupancy. Ideally, PET tracers retain target binding and biodistribution properties of the investigated drug. Previously, we developed a zirconium-89 PET tracer based on a long-circulating glucagon-like peptide 1 receptor agonist (GLP-1RA) using desferrioxamine (DFO) as a chelator. Here, we aimed to develop an improved zirconium-89-labeled GLP-1RA with increased molar activity to increase the uptake in low receptor density tissues, such as brain. Furthermore, we aimed at reducing tracer accumulation in the kidneys. Introducing up to four additional Zr-DFOs resulted in higher molar activity and stability, while retaining potency. Branched placement of DFOs was especially beneficial. Tracers with either two or four DFOs had similar biodistribution as the tracer with one DFO in vivo, albeit increased kidney and liver uptake. Reduced kidney accumulation was achieved by introducing an enzymatically cleavable Met-Val-Lys (MVK) linker motif between the chelator and the peptide.

Radboud University, 11 mei 2023, Promotores : Herpen, C.M.L. van, Heuvel, M. van den, Heskamp, S. Co-promotor : Aarntzen, E.H.J.G., Contains fulltext : 292271.pdf (Publisher’s version ) (Closed access)

Item does not contain fulltext, Limited diffusion of oxygen in combination with increased oxygen consumption leads to chronic hypoxia in most solid malignancies. This scarcity of oxygen is known to induce radioresistance and leads to an immunosuppressive microenvironment. Carbonic anhydrase IX (CAIX) is an enzyme functioning as a catalyzer for acid export in hypoxic cells and is an endogenous biomarker for chronic hypoxia. The aim of this study is to develop a radiolabeled antibody that recognizes murine CAIX to visualize chronic hypoxia in syngeneic tumor models and to study the immune cell population in these hypoxic areas. An anti-mCAIX antibody (MSC3) was conjugated to diethylenetriaminepentaacetic acid (DTPA) and radiolabeled with indium-111 ((111)In). CAIX expression on murine tumor cells was determined using flow cytometry, and in vitro affinity of [(111)In]In-MSC3 was analyzed in a competitive binding assay. Ex vivo biodistribution studies were performed to determine in vivo radiotracer distribution. CAIX(+) tumor fractions were determined by mCAIX microSPECT/CT, and the tumor microenvironment was analyzed using immunohistochemistry and autoradiography. We showed that [(111)In]In-MSC3 binds to CAIX-expressing (CAIX(+)) murine cells in vitro and accumulates in CAIX(+) areas in vivo. We optimized the use of [(111)In]In-MSC3 for preclinical imaging such that it can be applied in syngeneic mouse models and showed that we can quantitatively distinguish between tumor models with varying CAIX(+) fractions by ex vivo analyses and in vivo mCAIX microSPECT/CT. Analysis of the tumor microenvironment identified these CAIX(+) areas as less infiltrated by immune cells. Together these data demonstrate that mCAIX microSPECT/CT is a sensitive technique to visualize hypoxic CAIX(+) tumor areas that exhibit reduced infiltration of immune cells in syngeneic mouse models. In the future, this technique may enable visualization of CAIX expression before or during hypoxia-targeted or hypoxia-reducing treatments.

Contains fulltext : 294765.pdf (Publisher’s version ) (Open Access), Adoptive T cell therapy has successfully been implemented for the treatment of cancer. Nevertheless, ex vivo expansion of T cells by artificial antigen-presenting cells (aAPCs) remains cumbersome and can compromise T cell functionality, thereby limiting their therapeutic potential. We propose a radically different approach aimed at direct expansion of T cells in vivo, thereby omitting the need for large-scale ex vivo T cell production. We engineered nanosized immunofilaments (IFs), with a soluble semiflexible polyisocyanopeptide backbone that presents peptide-loaded major histocompatibility complexes and costimulatory molecules multivalently. IFs readily activated and expanded antigen-specific T cells like natural APCs, as evidenced by transcriptomic analyses of T cells. Upon intravenous injection, IFs reach the spleen and lymph nodes and induce antigen-specific T cell responses in vivo. Moreover, IFs display strong antitumor efficacy resulting in inhibition of the formation of melanoma metastases and reduction of primary tumor growth in synergy with immune checkpoint blockade. In conclusion, nanosized IFs represent a powerful modular platform for direct activation and expansion of antigen-specific T cells in vivo, which can greatly contribute to cancer immunotherapy.

Contains fulltext : 294525.pdf (Publisher’s version ) (Open Access), PET imaging of the glucagon-like peptide-1 receptor (GLP-1R) using radiolabeled exendin is a promising imaging method to detect insulinomas. However, high renal accumulation of radiolabeled exendin could hamper the detection of small insulinomas in proximity to the kidneys and limit its use as a radiotherapeutic agent. Here, we report two new exendin analogues for GLP-1R imaging and therapy, designed to reduce renal retention by incorporating a cleavable methionine-isoleucine (Met-Ile) linker. We examined the renal retention and insulinoma targeting properties of these new exendin analogues in a nude mouse model bearing subcutaneous GLP-1R-expressing insulinomas. NOTA or DOTA was conjugated via a methionine-isoleucine linker to the C-terminus of exendin-4 (NOTA-MI-exendin-4 or DOTA-MI-exendin-4). NOTA- and DOTA-exendin-4 without the linker were used as references. The affinity for GLP-1R was determined in a competitive binding assay using GLP-1R transfected cells. Biodistribution of [(68)Ga]Ga-NOTA-exendin-4, [(68)Ga]Ga-NOTA-MI-exendin-4, [(177)Lu]Lu-DOTA-exendin-4, and [(177)Lu]Lu-DOTA-MI-exendin-4 was determined in INS-1 tumor-bearing BALB/c nude mice, and PET/CT was acquired to visualize renal retention and tumor targeting. For all tracers, dosimetric calculations were performed to determine the kidney self-dose. The affinity for GLP-1R was in the low nanomolar range (<11 nM) for all peptides. In vivo biodistribution revealed a significantly lower kidney uptake of [(68)Ga]Ga-NOTA-MI-exendin-4 at 4 h post-injection (p.i.) (34.2 ± 4.2 %IA/g), compared with [(68)Ga]Ga-NOTA-exendin-4 (128 ± 10 %IA/g). Accumulation of [(68)Ga]Ga-NOTA-MI-exendin-4 in the tumor was 25.0 ± 8.0 %IA/g 4 h p.i., which was similar to that of [(68)Ga]Ga-NOTA-exendin-4 (24.9 ± 9.3 %IA/g). This resulted in an improved tumor-to-kidney ratio from 0.2 ± 0.0 to 0.8 ± 0.3. PET/CT confirmed the findings in the biodistribution studies. The kidney uptake of [(177)Lu]Lu-DOTA-MI-exendin-4 was 39.4 ± 6.3

01 juli 2023, Contains fulltext : 294532.pdf (Publisher’s version ) (Open Access), PURPOSE: Incomplete resection of prostate cancer (PCa) results in increased risk of disease recurrence. Combined fluorescence-guided surgery with tumor-targeted photodynamic therapy (tPDT) may help to achieve complete tumor eradication. We developed a prostate-specific membrane antigen (PSMA) ligand consisting of a DOTA chelator for (111)In labeling and a fluorophore/photosensitizer IRDye700DX (PSMA-N064). We evaluated the efficacy of PSMA-tPDT using PSMA-N064 in cell viability assays, a mouse xenograft model and in an ex vivo incubation study on fresh human PCa tissue. METHODS: In vitro, therapeutic efficacy of PSMA-N064 was evaluated using PSMA-positive LS174T cells and LS174T wild-type cells. In vivo, PSMA-N064-mediated tPDT was tested in immunodeficient BALB/c mice-bearing PSMA-positive LS174T xenografts. Tumor growth and survival were compared to control mice that received either NIR light or ligand injection only. Ex vivo tPDT efficacy was evaluated in excised fresh human PCa tissue incubated with PSMA-N064. RESULTS: In vitro, tPDT led to a PSMA-specific light- and ligand dose-dependent loss in cell viability. In vivo, tPDT-induced tumor cell apoptosis, delayed tumor growth, and significantly improved survival (p = 0.004) of the treated PSMA-positive tumor-bearing mice compared with the controls. In fresh ex vivo human PCa tissue, apoptosis was significantly increased in PSMA-tPDT-treated samples compared to non-treated control samples (p = 0.037). CONCLUSION: This study showed the feasibility of PSMA-N064-mediated tPDT in cell assays, a xenograft model and excised fresh human PCa tissue. This paves the way to investigate the impact of in vivo PSMA-tPDT on surgical outcome in PCa patients.

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Contains fulltext : 247192.pdf (Publisher’s version ) (Open Access)

Radboud University, 11 maart 2022, Promotores : Vries, I.J.M. de, Heskamp, S., Srinivas, M. Co-promotor : Aarntzen, E.H.J.G., Contains fulltext : 246857.pdf (Publisher’s version ) (Open Access)

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Radboud University, 24 februari 2022, Promotores : Figdor, C.G., Heskamp, S. Co-promotor : Verdoes, M., Contains fulltext : 244752.pdf (Publisher’s version ) (Open Access)

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Item does not contain fulltext, Positron emission tomography (PET) is a molecular imaging modality that enables non-invasive visualization of tracer distribution and pharmacology. Recently, peptides with long half-lives allowed once-a-week dosing of glucagon-like peptide-1 receptor (GLP-1R) agonists with therapeutic applications in diabetes and obesity. PET imaging for such long-lived peptides is hindered by the typically used short-lived radionuclides. Zirconium-89 ((89)Zr) emerged as a promising PET radionuclide with a sufficiently long half-life to be applied for biodistribution studies of long-circulating biomolecules. A comparison between the biodistribution profiles obtained via (89)Zr-PET and the current standard, quantitative whole-body autoradiography (QWBA), will be valuable for the development of novel peptide drugs. We determined the PET biodistribution of a (89)Zr-labeled acylated peptide agonist of GLP-1R and compared it to the profile obtained by QWBA using analogous tritiated tracers for up to 1 week after administration. The plasma metabolic profile was obtained and identification was done for the tritiated tracers. We found that, at early time points, the biodistribution profiles agreed between PET and QWBA. At the latertime points, the (89)Zr tracer remained primarily trapped in the kidneys. The introduction of desferrioxamine (DFO) chelator reduced the peptide stability, and UPLC-MS analysis identified a circulating metabolite arising from DFO hydrolysis. Kidney accumulation of radiolabeled peptides and DFO metabolic instability may compromise biodistribution studies using (89)Zr-PET to support the development of new biopharmaceuticals. PET and QWBA biodistribution data correlated well during the absorption phase, but new and more stable (89)Zr chelators are needed for a more accurate description of the elimination phase.

Contains fulltext : 252039.pdf (Publisher’s version ) (Open Access), INTRODUCTION: The first generation ligands for prostate-specific membrane antigen (PSMA)-targeted radio- and fluorescence-guided surgery followed by adjuvant photodynamic therapy (PDT) have already shown the potential of this approach. Here, we developed three new photosensitizer-based dual-labeled PSMA ligands by crucial modification of existing PSMA ligand backbone structures (PSMA-1007/PSMA-617) for multimodal imaging and targeted PDT of PCa. METHODS: Various new PSMA ligands were synthesized using solid-phase chemistry and provided with a DOTA chelator for (111)In labeling and the fluorophore/photosensitizer IRDye700DX. The performance of three new dual-labeled ligands was compared with a previously published first-generation ligand (PSMA-N064) and a control ligand with an incomplete PSMA-binding motif. PSMA specificity, affinity, and PDT efficacy of these ligands were determined in LS174T-PSMA cells and control LS174T wildtype cells. Tumor targeting properties were evaluated in BALB/c nude mice with subcutaneous LS174T-PSMA and LS174T wildtype tumors using microSPECT/CT imaging, fluorescence imaging, and biodistribution studies after dissection. RESULTS: In order to synthesize the new dual-labeled ligands, we modified the PSMA peptide linker by substitution of a glutamic acid into a lysine residue, providing a handle for conjugation of multiple functional moieties. Ligand optimization showed that the new backbone structure leads to high-affinity PSMA ligands (all IC50 < 50 nM). Moreover, ligand-mediated PDT led to a PSMA-specific decrease in cell viability in vitro (P < 0.001). Linker modification significantly improved tumor targeting compared to the previously developed PSMA-N064 ligand (>/= 20 +/- 3%ID/g vs 14 +/- 2%ID/g, P < 0.01) and enabled specific visualization of PMSA-positive tumors using both radionuclide and fluorescence imaging in mice. CONCLUSION: The new high-affinity dual-labeled PSMA-targeting ligands with optimized backbone compositions showed

Item does not contain fulltext, RATIONALE: Prolonged in vivo evaluation of PSMA tracers could improve tumor imaging and patient selection for (177)Lu-PSMA-617 and (177)Lu-PSMA-I&T. In this study, we present the radiolabeling method of PSMA-617 and PSMA-I&T with the long-lived positron emitter (89)Zr to enable PET imaging up to 7 days post-injection. We compared the biodistribution of (89)Zr-PSMA-617 and (89)Zr-PSMA-I&T to those of (177)Lu-PSMA-617 and (177)Lu-PSMA-I&T, respectively, in a PSMA(+) xenograft model. Moreover, we provide the first human (89)Zr-PSMA-617 images. MATERIALS AND METHODS: PSMA ligands were labeled with 50-55 MBq [(89)Zr]ZrCl4 using a two-step labeling protocol. For biodistribution, BALB/c nude mice bearing PSMA(+) and PSMA(-) xenografts received 0.6 microg (0.6-1 MBq) of (89)Zr-PSMA-617, (89)Zr-PSMA-I&T, (177)Lu-PSMA-617, or (177)Lu-PSMA-I&T intravenously. Ex vivo biodistribution and PET/SPECT imaging were performed up to 168 h post-injection. Dosimetry was performed from the biodistribution data. The patient received 90.5 MBq (89)Zr-PSMA-617 followed by PET/CT imaging. RESULTS: (89)Zr-labeled PSMA ligands showed a comparable ex vivo biodistribution to its respective (177)Lu-labeled counterparts with high tumor accumulation in the PSMA(+) xenografts. However, using a dose estimation model for (177)Lu, absorbed radiation dose in bone and kidneys differed among the (177)Lu-PSMA and (89)Zr-PSMA tracers. (89)Zr-PSMA-617 PET in the first human patient showed high contrast of PSMA expressing tissues up to 48 h post-injection. CONCLUSION: PSMA-617 and PSMA-I&T were successfully labeled with (89)Zr and demonstrated high uptake in PSMA(+) xenografts, which enabled PET up to 168 h post-injection. The biodistribution of (89)Zr-PSMA-I&T and (89)Zr-PSMA-617 resembled that of (177)Lu-PSMA-I&T and (177)Lu-PSMA-617, respectively. The first patient (89)Zr-PSMA-617 PET images were of high quality warranting further clinical investigation.

Contains fulltext : 283433.pdf (Publisher’s version ) (Open Access), Hypoxic areas are present in the majority of solid tumors, and hypoxia is associated with resistance to therapies and poor outcomes. A transmembrane protein that is upregulated by tumor cells that have adapted to hypoxic conditions is carbonic anhydrase IX (CAIX). Therefore, noninvasive imaging of CAIX could be of prognostic value, and it could steer treatment strategies. The aim of this study was to compare variants of CAIX-binding VHH B9, with and without a C-terminal albumin-binding domain with varying affinity (ABD(low) and ABD(high)), for SPECT imaging of CAIX expression. The binding affinity and internalization of the various B9-variants were analyzed using SK-RC-52 cells. Biodistribution studies were performed in mice with subcutaneous SCCNij153 human head and neck cancer xenografts. Tracer uptake was determined by ex vivo radioactivity counting and visualized by SPECT/CT imaging. Furthermore, autoradiography images of tumor sections were spatially correlated with CAIX immunohistochemistry. B9-variants demonstrated a similar moderate affinity for CAIX in vitro. Maximal tumor uptake and acceptable tumor-to-blood ratios were found in the SCCNij153 model at 4 h post injection for [(111)In]In-DTPA-B9 (0.51 ± 0.08%ID/g and 8.1 ± 0.85, respectively), 24 h post injection for [(111)In]In-DTPA-B9-ABD(low) (2.39 ± 0.44%ID/g and 3.66 ± 0.81, respectively) and at 72 h post injection for [(111)In]In-DTPA-B9-ABD(high) (8.7 ± 1.34%ID/g and 2.43 ± 0.15, respectively)(.) An excess of unlabeled monoclonal anti-CAIX antibody efficiently inhibited tumor uptake of [(111)In]In-DTPA-B9, while only a partial reduction of [(111)In]In-DTPA-B9-ABD(low) and [(111)In]In-DTPA-B9-ABD(high) uptake was found. Immunohistochemistry and autoradiography images showed colocalization of all B9-variants with CAIX expression; however, [(111)In]In-DTPA-B9-ABD(low) and [(111)In]In-DTPA-B9-ABD(high) also accumulated in non-CAIX expressing regions. Tumor uptake of [(111)In]In-DTPA-B9-ABD(low) and [(111)

Radboud University, 02 september 2022, Promotores : Nagarajah, J., Gotthardt, M., Heskamp, S. Co-promotor : Mehra, N., Contains fulltext : 252883.pdf (Publisher’s version ) (Open Access)

Radboud University, 08 september 2022, Promotores : Heskamp, S., Rijpkema, M.J.P. Co-promotores : Lütje, S., Lowik, D.W.P.M., Contains fulltext : 252882.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 253638.pdf (Publisher’s version ) (Open Access)

Item does not contain fulltext, PURPOSE: Prostate-specific membrane antigen radioligand therapy (PSMA-RLT) is a novel treatment for castration-resistant prostate cancer (mCRPC). While the majority of patients responds to PSMA-RLT, with 10-15% having an exceptional response, approximately 30% of patients is unresponsive to PSMA-RLT. The molecular underpinning may in part explain these varying responses. This study investigated alterations in DNA damage repair (DDR) genes in tumour biopsies and their association with response to PSMA-RLT. METHODS: A predefined retrospective cohort study was performed in mCRPC patients of whom the tumours had undergone next-generation sequencing of 40 DDR genes and received Lu-177-PSMA and/or Ac-225-PSMA-RLT. The primary outcome of this study was to compare the progression free survival (PFS) after PSMA-RLT for patients with and without pathogenic DDR aberrations in their tumour. Secondary outcomes were prostate-specific antigen (PSA) response and overall survival (OS). RESULTS: A total of 40 patients were included of which seventeen had a tumour with a pathogenic DDR aberration (DDR+), of which eight had defects in BRCA1/2. DDR+ patients had an equal varying response to PSMA-RLT compared to those without pathological DDR anomalies (DDR-) in terms of PFS (5.9 vs. 6.4 months, respectively; HR 1.14; 95% CI 0.58-2.25; p = 0.71), ≥50% PSA response (59% vs. 65%, respectively; p = 0.75) or OS (11.1 vs. 10.7 months, respectively; HR 1.40; 95% CI: 0.68-2.91; p = 0.36). CONCLUSION: In this study of a selected cohort, pathogenic DDR aberrations were not associated with exceptional responsiveness to PSMA-RLT. Translational studies in larger prospective cohorts are warranted to associate DDR gene defects with differential responses to PSMA-RLT.

Contains fulltext : 245218.pdf (Publisher’s version ) (Open Access), In the past decade, a growing body of literature has reported promising results for prostate-specific membrane antigen (PSMA)-targeted radionuclide imaging and therapy in prostate cancer. First clinical studies evaluating the efficacy of [(177)Lu]Lu-PSMA radioligand therapy (PSMA-RLT) demonstrated favorable results in prostate cancer patients. [(177)Lu]Lu-PSMA is generally well tolerated due to its limited side effects. While PSMA is highly overexpressed in prostate cancer cells, varying degrees of PSMA expression have been reported in other malignancies as well, particularly in the tumor-associated neovasculature. Hence, it is anticipated that PSMA-RLT could be explored for other solid cancers. Here, we describe the current knowledge of PSMA expression in other solid cancers and define a perspective towards broader clinical implementation of PSMA-RLT. This review focuses specifically on salivary gland cancer, glioblastoma, thyroid cancer, renal cell carcinoma, hepatocellular carcinoma, lung cancer, and breast cancer. An overview of the (pre)clinical data on PSMA immunohistochemistry and PSMA PET/CT imaging is provided and summarized. Furthermore, the first clinical reports of non-prostate cancer patients treated with PSMA-RLT are described.

Contains fulltext : 244629.pdf (Publisher’s version ) (Open Access), The exponential growth of research on cell-based therapy is in major need of reliable and sensitive tracking of a small number of therapeutic cells to improve our understanding of the in vivo cell-targeting properties. (111)In-labeled poly(lactic-co-glycolic acid) with a primary amine endcap nanoparticles ([(111)In]In-PLGA-NH(2) NPs) were previously used for cell labeling and in vivo tracking, using SPECT/CT imaging. However, to detect a low number of cells, a higher sensitivity of PET is preferred. Therefore, we developed (89)Zr-labeled NPs for ex vivo cell labeling and in vivo cell tracking, using PET/MRI. We intrinsically and efficiently labeled PLGA-NH(2) NPs with [(89)Zr]ZrCl(4). In vitro, [(89)Zr]Zr-PLGA-NH(2) NPs retained the radionuclide over a period of 2 weeks in PBS and human serum. THP-1 (human monocyte cell line) cells could be labeled with the NPs and retained the radionuclide over a period of 2 days, with no negative effect on cell viability (specific activity 279 ± 10 kBq/10(6) cells). PET/MRI imaging could detect low numbers of [(89)Zr]Zr-THP-1 cells (10,000 and 100,000 cells) injected subcutaneously in Matrigel. Last, in vivo tracking of the [(89)Zr]Zr-THP-1 cells upon intravenous injection showed specific accumulation in local intramuscular Staphylococcus aureus infection and infiltration into MDA-MB-231 tumors. In conclusion, we showed that [(89)Zr]Zr-PLGA-NH(2) NPs can be used for immune-cell labeling and subsequent in vivo tracking of a small number of cells in different disease models.

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Contains fulltext : 239797.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 228671.pdf (publisher's version ) (Open Access)

Contains fulltext : 235310.pdf (Publisher’s version ) (Closed access), PURPOSE: [(177)Lu]Lu-PSMA-617 radioligand therapy ((177)Lu-PSMA) is a novel treatment for metastatic castration-resistant prostate cancer (mCRPC), which could also be applied to patients with metastatic hormone-sensitive prostate cancer (mHSPC) with PSMA expression. In this prospective study (NCT03828838), we analyzed toxicity, radiation doses, and treatment effect of (177)Lu-PSMA in pateints with low-volume mHSPC. PATIENTS AND METHODS: Ten progressive patients with mHSPC following local treatment, with a maximum of ten metastatic lesions on [(68)Ga]Ga-PSMA-11 PET/diagnostic-CT imaging (PSMA-PET) and serum PSA doubling time <6 months received two cycles of (177)Lu-PSMA. Whole-body single-photon emission CT/CT (SPECT/CT) and blood dosimetry was performed to calculate doses to the tumors and organs at risk (OAR). Adverse events (AE), laboratory values (monitoring response and toxicity), and quality of life were monitored until week 24 after cycle 2, the end of study (EOS). All patients underwent PSMA-PET at screening, 8 weeks after cycle 1, 12 weeks after cycle 2, and at EOS. RESULTS: All patients received two cycles of (177)Lu-PSMA without complications. No treatment-related grade III-IV adverse events were observed. According to dosimetry, none of the OAR reached threshold doses for radiation-related toxicity. Moreover, all target lesions received a higher radiation dose than the OAR. All 10 patients showed altered PSA kinetics, postponed androgen deprivation therapy, and maintained good quality of life. Half of the patients showed a PSA response of more than 50%. One patient had a complete response on PSMA-PET imaging until EOS and two others had only minimal residual disease. CONCLUSIONS: (177)Lu-PSMA appeared to be a feasible and safe treatment modality in patients with low-volume mHSPC.

Contains fulltext : 232237.pdf (Publisher’s version ) (Open Access)

Item does not contain fulltext, As tumors grow, they upregulate glycolytic and oxidative metabolism to support their increased and altered energetic demands. These metabolic changes have major effects on the tumor microenvironment. One of the properties leading to this aberrant metabolism is hypoxia, which occurs when tumors outgrow their often-chaotic vasculature. This scarcity of oxygen is known to induce radioresistance but can also have a disrupting effect on the antitumor immune response. Hypoxia inhibits immune effector cell function, while immune cells with a more suppressing phenotype become more active. Therefore, hypoxia strongly affects the efficacy of both radiotherapy and immunotherapy, as well as this therapy combination. Inhibition of oxidative phosphorylation (OXPHOS) is gaining interest for its ability to combat tumor hypoxia, and there are strong indications that this results in a reactivation of the immune response. This strategy decreases oxygen consumption, leading to better oxygenation of hypoxic tumor areas and eventually an increase in immunogenic cell death induced by radio-immunotherapy combinations. Promising preclinical improvements in radio- and immunotherapy efficacy have been observed by the hypoxia-reducing effect of OXPHOS inhibitors and several compounds are currently in clinical trials for their anticancer properties. Here, we will review the pharmacologic attenuation of tumor hypoxia using OXPHOS inhibitors, with emphasis on their impact on the intrinsic antitumor immune response and how this affects the efficacy of (combined) radio- and immunotherapy.

Contains fulltext : 236797.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 237162.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 247592.pdf (Publisher’s version ) (Closed access)

Contains fulltext : 247593.pdf (Publisher’s version ) (Closed access)

Item does not contain fulltext, Metabolic reprogramming is recognized as one of the hallmarks of cancer. Alterations in the micro-environmental metabolic characteristics are recognized as important tools for cancer cells to interact with the resident and infiltrating T-cells within this tumor microenvironment. Cancer-induced metabolic changes in the micro-environment also affect treatment outcomes. In particular, immune therapy efficacy might be blunted because of somatic mutation-driven metabolic determinants of lung cancer such as acidity and oxygenation status. Based on these observations, new onco-immunological treatment strategies increasingly include drugs that interfere with metabolic pathways that consequently affect the composition of the lung cancer tumor microenvironment (TME). Positron emission tomography (PET) imaging has developed a wide array of tracers targeting metabolic pathways, originally intended to improve cancer detection and staging. Paralleling the developments in understanding metabolic reprogramming in cancer cells, as well as its effects on stromal, immune, and endothelial cells, a wave of studies with additional imaging tracers has been published. These tracers are yet underexploited in the perspective of immune therapy. In this review, we provide an overview of currently available PET tracers for clinical studies and discuss their potential roles in the development of effective immune therapeutic strategies, with a focus on lung cancer. We report on ongoing efforts that include PET/CT to understand the outcomes of interactions between cancer cells and T-cells in the lung cancer microenvironment, and we identify areas of research which are yet unchartered. Thereby, we aim to provide a starting point for molecular imaging driven studies to understand and exploit metabolic features of lung cancer to optimize immune therapy.

Radboud University, 30 oktober 2020, Promotores : Bussink, J., Boerman, O.C. Co-promotores : Hoeben, B.A.W., Heskamp, S., Contains fulltext : 224759.pdf (publisher's version ) (Open Access)

Contains fulltext : 220554.pdf (publisher's version ) (Open Access), Platinum-based chemotherapeutics exhibit excellent antitumor properties. However, these drugs cause severe side effects including toxicity, drug resistance, and lack of tumor selectivity. Tumor-targeted drug delivery has demonstrated great potential to overcome these drawbacks. Herein, we aimed to design radioactive bisphosphonate-functionalized platinum ((195m)Pt-BP) complexes to confirm preferential accumulation of these Pt-based drugs in metabolically active bone. In vitro NMR studies revealed that release of Pt from Pt BP complexes increased with decreasing pH. Upon systemic administration to mice, Pt-BP exhibited a 4.5-fold higher affinity to bone compared to platinum complexes lacking the bone-seeking bisphosphonate moiety. These Pt-BP complexes formed less Pt-DNA adducts compared to bisphosphonate-free platinum complexes, indicating that in vivo release of Pt from Pt-BP complexes proceeded relatively slow. Subsequently, radioactive (195m)Pt-BP complexes were synthesized using (195m)Pt(NO3)2(en) as precursor and injected intravenously into mice. Specific accumulation of (195m)Pt-BP was observed at skeletal sites with high metabolic activity using micro-SPECT/CT imaging. Furthermore, laser ablation-ICP-MS imaging of proximal tibia sections confirmed that (195m)Pt BP co-localized with calcium in the trabeculae of mice tibia.