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177 Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) is used clinically to treat metastasized or unresectable neuroendocrine tumors (NETs). Although 177 Lu-DOTATATE is mostly well tolerated in patients, bone marrow suppression and long-term renal toxicity are still side effects that should be considered. Amino acids are often used to minimize renal radiotoxicity, however, they are associated with nausea and vomiting in patients. α 1 -microglobulin (A1M) is an antioxidant with heme- and radical-scavenging abilities. A recombinant form (rA1M) has previously been shown to be renoprotective in preclinical models, including in PRRT-induced kidney damage. Here, we further investigated rA1M's renal protective effect in a mouse 177 Lu-DOTATATE model in terms of administration route and dosing regimen and as a combined therapy with amino acids (Vamin). Moreover, we investigated the protective effect of rA1M on peripheral blood and bone marrow cells, as well as circulatory biomarkers. Intravenous (i.v.) administration of rA1M reduced albuminuria levels and circulatory levels of the oxidative stress-related protein fibroblast growth factor-21 (FGF-21). Dual injections of rA1M (i.e., at 0 and 24 h post- 177 Lu-DOTATATE administration) preserved bone marrow cellularity and peripheral blood reticulocytes. Administration of Vamin, alone or in combination with rA1M, did not show any protection of bone marrow cellularity or peripheral reticulocytes. In conclusion, this study suggests that rA1M, administered i.v. for two consecutive days in conjunction with 177 Lu-DOTATATE, may reduce hematopoietic and kidney toxicity during PRRT with 177 Lu-DOTATATE.

α 1 -Microglobulin (A1M) is an antioxidant found in all vertebrates, including humans. It has enzymatic reductase activity and can scavenge radicals and bind free heme groups. Infused recombinant A1M accumulates in the kidneys and has therefore been successful in protecting kidney injuries in different animal models. In this review, we focus on A1M as a radioprotector of the kidneys during peptide receptor radionuclide/radioligand therapy (PRRT/RLT). Patients with, e.g., neuroendocrine tumors or castration resistant prostate cancer can be treated by administration of radiolabeled small molecules which target and therefore enable the irradiation and killing of cancer cells through specific receptor interaction. The treatment is not curative, and kidney toxicity has been reported as a side effect since the small, radiolabeled substances are retained and excreted through the kidneys. In recent studies, A1M was shown to have radioprotective effects on cell cultures as well as having a similar biodistribution as the somatostatin analogue peptide 177 Lu-DOTATATE after intravenous infusion in mice. Therefore, several animal studies were conducted to investigate the in vivo radioprotective potential of A1M towards kidneys. The results of these studies demonstrated that A1M co-infusion yielded protection against kidney toxicity and improved overall survival in mouse models. Moreover, two different mouse studies reported that A1M did not interfere with tumor treatment itself. Here, we give an overview of radionuclide therapy, the A1M physiology and the results from the radioprotector studies of the protein.

Anti-prostate specific membrane antigen (PSMA) radioligand therapy is promising but not curative in castration resistant prostate cancer. One way to broaden the therapeutic index could be to administer higher doses in combination with radioprotectors, since administered radioactivity is kept low today in order to avoid side-effects from a high absorbed dose to healthy tissue. Here, we investigated the human radical scavenger α 1 -microglobulin (A1M) together with 177-Lutetium ( 177 Lu) labeled PSMA-617 in preclinical models with respect to therapeutic efficacy and kidney toxicity. Nude mice with subcutaneous LNCaP xenografts were injected with 50 or 100 MBq of [ 177 Lu]Lu-PSMA-617, with or without injections of recombinant A1M (rA1M) (at T = 0 and T = 24 h). Kidney absorbed dose was calculated to 7.36 Gy at 4 days post a 100 MBq injection. Activity distribution was imaged with Single-Photon Emission Computed Tomography (SPECT) at 24 h. Tumor volumes were measured continuously, and kidneys and blood were collected at termination (3-4 days and 3-4 weeks after injections). In a parallel set of experiments, mice were given [ 177 Lu]Lu-PSMA-617 and rA1M as above and dynamic technetium-99m mercaptoacetyltriglycine ([ 99m Tc]Tc-MAG3) SPECT imaging was performed prior to injection, and 3- and 6-months post injection. Blood and urine were continuously sampled. At termination (6 months) the kidneys were resected. Biomarkers of kidney function, expression of stress genes and kidney histopathology were analyzed. [ 177 Lu]Lu-PSMA-617 uptake, in tumors and kidneys, as well as treatment efficacy did not differ between rA1M and vehicle groups. In mice given rA1M, [ 99m Tc]Tc-MAG3 imaging revealed a significantly higher slope of initial uptake at three months compared to mice co-injected with [ 177 Lu]Lu-PSMA-617 and vehicle. Little or no change compared to control was seen in urine albumin, serum/plasma urea levels, RT-qPCR analysis of stress response genes and in the kidney histopathological evaluation. In conclusion, [ 99m Tc]Tc-MAG3 imaging presented itself as a sensitive tool to detect changes in kidney function revealing that administration of rA1M has a potentially positive effect on kidney perfusion and tubular function when combined with [ 177 Lu]Lu-PSMA-617 therapy. Furthermore, we could show that rA1M did not affect anti-PSMA radioligand therapy efficacy.

Background: Urine cytology evaluation is an effective test in the detection of high-grade urothelial carcinoma (HGUC). While the guideline distinguishes the 2 categories: "positive for HGUC" (PHGUC) and "suspicious for HGUC" (SHGUC), the association between these categories with their subsequent follow-up biopsies remains unclear. This study aims to determine and compare the positive predictive value (PPV) of the specimens in PHGUC and SHGUC categories with their respective histologic diagnoses., Methods: During the period of 03/01/2008 to 07/31/2018, urine cytology cases diagnosed as PHGUC and SHGUC with subsequent bladder biopsy within 12 months were retrieved. All cases were correlated with first biopsy obtained during 12 months of cytology specimen. Biopsy result with HGUC, carcinoma in situ, or non-urothelial carcinoma diagnoses were considered as concordance., Results: 378 cases (229 SHGUC and 149 PHGUC) were identified from 263 patients. For the 229 SHGUC cases, the PPV was 72% (n = 166) and for the 149 PHGUC cases, the PPV was 85% (n = 127). While both categories have high PPV, they are statistically significant (p < 0.0001). Additionally, 33 cases were found to have low-grade urothelial carcinoma (LGUC), constituting a portion of discordant results., Conclusion: PHGUC and SHGUC categories are both associated with a high risk of malignancy, however, there is a statistically significant difference between them in our study, supporting the PSRUC guidelines of two separate categories. In instances when urine cytology is discordant with biopsy results, further investigation and clinical follow up is warranted. LGUC appears to remain a common pitfall especially in the suspicious category., (© 2020 Wiley Periodicals LLC.)

Glioblastoma multiforme (GBM) is an aggressive primary brain malignancy with a very poor prognosis. Researchers employ animal models to develop potential therapies. It is important that these models have clinical relevance. This means that old models, propagated for decades in cultures, should be questioned. Parameters to be evaluated include whether animals are immune competent or not, the infiltrative growth pattern of the tumor, tumor volume resulting in symptoms and growth rate. We here describe the growth pattern of an experimental glioblastoma model in detail with GFP positive glioblastoma cells in fully immune competent animals and study tumor growth rate and tumor mass as a function of time from inoculation. We were able to correlate findings made with classical immunohistochemistry and MR findings. The tumor growth rate was fitted by a Gompertz function. The model predicted the time until onset of symptoms for 5000 inoculated cells to 18.7±0.4 days, and the tumor mass at days 10 and 14, which are commonly used as the start of treatment in therapeutic studies, were 5.97±0.62 mg and 29.1±3.0 mg, respectively. We want to raise the question regarding the clinical relevance of the outline of glioblastoma experiments, where treatment is often initiated at a very early stage. The approach presented here could potentially be modified to gain information also from other tumor models.

Objectives: The aim of the study was to investigate therapeutic efficacy of single- or two-fraction radiotherapy in conjunction with IDO1-inhibition in a syngeneic rat glioblastoma model. IDO is known to cause immunosuppression through breakdown of tryptophan in the tumor microenvironment., Methods: Gene expression analyses of IDO in glioblastoma were performed with data from publicly available datasets. Fractionation studies were done on animals to evaluate tumor size, immune cell infiltration of tumors and serum profile on day 18 after tumor inoculation. Survival analyses were done with animals carrying intracranial glioblastomas comparing two-fraction radiotherapy+IDO1-inhibition to controls. IDO inhibition was achieved by administration of 1-methyl tryptophan (1-MT), and radiotherapy (RT) was delivered in doses of 8Gy., Results: The expression of IDO1 was increased on gene level in glioblastoma stem cells. Tumor size was significantly reduced in animals treated with 1-MT+RTx 2 (both long and short intervals, i.e. 7 and 4 days between the treatments) as compared to control animals, animals treated with only 1-MT or animals treated with 1-MT+RTx1. Serum levels of IL-1A were significantly altered in all treated animals as compared to control animals. Survival was significantly increased in the animals treated with 1-MT+RTx2 (7-day interval) compared to control animals., Conclusions: Addition of two-fraction RT to IDO1 inhibition with 1-MT significantly reduced tumor size in animals with glioblastoma. Survival was significantly increased in animals treated with two-fractioned RT+1-MT as compared to untreated controls increased significantly., Advances in Knowledge: The currently used combination of only two fractions of radiotherapy and immune therapy is a promising area of research, increasing efficacy compared to single fraction irradiation, while potentially lowering radiation side effects compared to radiation in current clinical practice., Competing Interests: The authors have declared that no competing interests exist.

Background/aims: Peptide receptor radionuclide therapy (PRRT) is becoming clinical routine for management of neuroendocrine tumours. The number of PRRT cycles is correlated with treatment effect but theoretically limited by off-target radiation damage to kidneys and bone marrow. New imaging biomarkers for assessment of PRRT tissue damage would enable evaluation of novel renal and bone marrow protective agents, as well as personalised PRRT treatment regiments., Methods: Mice treated with [177Lu]Lu-DOTA-TATE PRRT or vehicle were examined at baseline and following treatment with [18F]fluorothymidine (FLT) positron emission tomography (PET) and technetium-99m-mercapto-acetyl-tri-glycine ([99mTc]Tc-Mag3) single-photon emission tomography (SPECT) to assess dynamic changes in bone marrow proliferation and renal function, respectively., Results: Bone marrow proliferation as assessed by [18F]FLT was decreased 2 days after PRRT treatment, but not vehicle, compared to baseline (target-to-background ratio [TBRmax] baseline:1.69 ± 0.29 vs. TBRmax PRRT: 0.91 ± 0.02, p < 0.01). Renal function as assessed by [99mTc]Tc-Mag3 SPECT was similarly decreased 2 days following PRRT compared to vehicle (fractional uptake rate [FUR] vehicle: 0.030 ± 0.014 s-1 vs. FUR PRRT: 0.0051 ± 0.0028 s-1, p < 0.01)., Conclusion: [18F]FLT PET and [99mTc]Tc-Mag3 SPECT are promising techniques for assessing bone marrow and renal injury from [177Lu]Lu-DOTA-TATE PRRT and may potentially improve patient management by allowing evaluation of protective interventions as well as enabling personalised PRRT treatments., (© 2019 S. Karger AG, Basel.)

Pathology residency training is currently a time-intensive process, frequently extending up to 6 years in duration as residents complete 1 or 2 fellowships following graduation. Innovative training curricula may help address the impending changes in the health-care landscape, particularly future shortfalls in pathology staffing and changing health-care models that incorporate more work within interdisciplinary teams. Montefiore has created a novel residency training program aimed at accelerating the acquisition of competency in pathology, preparing residents for independent practice at the completion of residency training, and providing residents with the requisite adaptability and consultative skills to excel wherever they choose to practice. We describe the implementation of this novel pathology residency training curriculum at Montefiore Medical Center/Albert Einstein College of Medicine and the perception of residents in both the old curriculum and the new curriculum., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Aims: Peptide receptor radionuclide therapy (PRRT) is in clinical use today to treat metastatic neuroendocrine tumors. Infused, radiolabeled, somatostatin analog peptides target tumors that are killed by irradiation damage. The peptides, however, are also retained in kidneys due to glomerular filtration, and the administered doses must be limited to avoid kidney damage. The human radical scavenger and antioxidant, α 1 -microglobulin (A1M), has previously been shown to protect bystander tissue against irradiation damage and has pharmacokinetic and biodistribution properties similar to somatostatin analogs. In this study, we have investigated if A1M can be used as a renal protective agent in PRRT., Results: We describe nephroprotective effects of human recombinant A1M on the short- and long-term renal damage observed following lutetium 177 ( 177 Lu)-DOTATATE (150 MBq) exposure in BALB/c mice. After 1, 4, and 8 days (short term), 177 Lu-DOTATATE injections resulted in increased formation of DNA double-strand breaks in the renal cortex, upregulated expression of apoptosis and stress response-related genes, and proteinuria (albumin in urine), all of which were significantly suppressed by coadministration of A1M (7 mg/kg). After 6, 12, and 24 weeks (long term), 177 Lu-DOTATATE injections resulted in increased animal death, kidney lesions, glomerular loss, upregulation of stress genes, proteinuria, and plasma markers of reduced kidney function, all of which were suppressed by coadministration of A1M. Innovation and Conclusion: This study demonstrates that A1M effectively inhibits radiation-induced renal damage. The findings suggest that A1M may be used as a radioprotector during clinical PRRT, potentially facilitating improved tumor control and enabling more patients to receive treatment.

Aims: Human α 1 -microglobulin (A1M) is an endogenous reductase and radical- and heme-binding protein with physiological antioxidant protective functions. Recombinant human A1M (rA1M) has been shown to have therapeutic properties in animal models of preeclampsia, a pregnancy disease associated with oxidative stress. Recombinant A1M, however, lacks glycosylation, and shows lower solubility and stability than A1M purified from human plasma. The aims of this work were to (i) use site-directed mutagenesis to improve the physicochemical properties of rA1M, (ii) demonstrate that the physicochemically improved rA1M displays full in vitro cell protective effects as recombinant wild-type A1M (rA1M-wt), and (iii) show its therapeutic potential in vivo against acute kidney injury (AKI), another disease associated with oxidative stress., Results: A novel recombinant A1M-variant (rA1M-035) with three amino acid substitutions was constructed, successfully expressed, and purified. rA1M-035 had improved solubility and stability compared with rA1M-wt, and showed intact in vitro heme-binding, reductase, antioxidation, and cell protective activities. Both rA1M-035 and rA1M-wt showed, for the first time, potential in vivo protective effects on kidneys using a mouse rhabdomyolysis glycerol injection model of AKI., Innovation: A novel recombinant A1M-variant, rA1M-035, was engineered. This protein showed improved solubility and stability compared with rA1M-wt, full in vitro functional activity, and potential protection against AKI in an in vivo rhabdomyolysis mouse model., Conclusion: The new rA1M-035 is a better drug candidate than rA1M-wt for treatment of AKI and preeclampsia in human patients.

Purpose: Glioblastoma multiforme (GBM) or astrocytoma grade IV is the most common type of primary brain tumor in adults. In the present study, we investigate the role of the complement system in the glioblastoma situation in an experimental model, since we have previously been able to show a blockade of this system in the glioblastoma setting., Technique and Results: A GFP-positive glioblastoma cell line was used to induce glioblastomas subcutaneously in rats (n=42). Antibodies against C1-Inactivator (C1-IA) were used to try to re-activate the complement system. We were able to demonstrate an increased survival in rats treated with anti-C1-IA with an intratumoral route, and we could establish the same the results in a second series. Serum analyses revealed decreased levels of IL-1b and GM-CSF in animals 24 days after tumor cell inoculation in the anti-C1-IA group when compared to controls. Immunohistochemistry revealed decreased expression of C1-IA following treatment., Interpretation: These results are in line with our previous work showing an upregulation of C1-IA, which is able to block the classical complement pathway, in glioblastomas. Treatment with antibodies against C1-IA seems to be beneficial in the glioblastoma situation, and no side effects could be seen in our experiments., Competing Interests: CONFLICTS OF INTEREST The authors do not have any conflicts of interest.

Objective: Recent research has shown that combining radiotherapy and immunotherapy can counteract the ability of cancer to evade and suppress the native immune system. To optimise the synergy of the combined therapies, factors such as radiation dose and fractionation must be considered, alongside numerous parameters resulting from the complexity of cancer-immune system interactions. It is instructive to use mathematical models to tackle this problem., Methods: In this work, we adapted a model primarily to describe the synergistic effect between single-fraction radiotherapy and immunotherapy (1-methyl tryptophan) observed in previous experiments with glioblastoma-carrying rats. We also showed how the model can be used to generate hypotheses on the outcome of other treatment fractionation schemes., Results: The model successfully reproduced the results of the experiments. Moreover, it provided support for the hypothesis that, for a given biologically effective dose, the efficacy of the combination therapy and the synergy between the two therapies are favoured by the administration of radiotherapy in a hypofractionated regime. Furthermore, for a double-fraction irradiation regimen, the synergy is favoured by a short time interval between the treatment fractions., Conclusion: It was concluded that the model could be fitted to reproduce the experimental data well within its uncertainties. It was also demonstrated that the fitted model can be used to form hypotheses to be validated by further pre-clinical experiments. Advances in knowledge: The results of this work support the hypothesis that the synergetic action of combined radiotherapy and immunotherapy is favoured by using a hypofractionated radiation treatment regimen, given over a short time interval.

Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor, and available experimental and routine therapies result in limited survival benefits. A vulnerability of GBM cells to catastrophic vacuolization and cell death, a process termed methuosis, induced by Vacquinol-1 (VQ-1) has been described earlier. In the present study, we investigate the efficacy of VQ-1 treatment in two syngeneic rat GBM models, RG2 and NS1. VQ-1 treatment affected growth of both RG2 and NS1 cells in vitro . Intracranially, significant reduction in RG2 tumor size was observed, although no effect was seen on overall survival. No survival advantage or effect on tumor size was seen in animals carrying the NS1 models compared to untreated controls. Furthermore, immunological staining of FOXP3, CD4 and CD8 showed no marked difference in immune cell infiltrate in tumor environment following treatment. Taken together, a survival advantage of VQ-1 treatment alone could not be demonstrated here, even though some effect upon tumor size was seen. Staining for immune cell markers did not indicate that VQ-1 either reduced or increased host anti-tumor immune response., Competing Interests: CONFLICTS OF INTEREST The authors declare that there are no conflicts of interest.

Peptide receptor radionuclide therapy (PRRT) has been in clinical use for 15 years to treat metastatic neuroendocrine tumors. PRRT is limited by reabsorption and retention of the administered radiolabeled somatostatin analogues in the proximal tubule. Consequently, it is essential to develop and employ methods to protect the kidneys during PRRT. Today, infusion of positively charged amino acids is the standard method of kidney protection. Other methods, such as administration of amifostine, are still under evaluation and show promising results. α₁-microglobulin (A1M) is a reductase and radical scavenging protein ubiquitously present in plasma and extravascular tissue. Human A1M has antioxidation properties and has been shown to prevent radiation-induced in vitro cell damage and protect non-irradiated surrounding cells. It has recently been shown in mice that exogenously infused A1M and the somatostatin analogue octreotide are co-localized in proximal tubules of the kidney after intravenous infusion. In this review we describe the current situation of kidney protection during PRRT, discuss the necessity and implications of more precise dosimetry and present A1M as a new, potential candidate for renal protection during PRRT and related targeted radionuclide therapies.

Peptide-receptor radionuclide therapy (PRRT) is a systemically administrated molecular targeted radiation therapy for treatment of neuroendocrine tumors. Fifteen years of clinical use show that renal toxicity, due to glomerular filtration of the peptides followed by local generation of highly reactive free radicals, is the main side-effect that limits the maximum activity that can be administrated for efficient therapy. α1-microglobulin (A1M) is an endogenous radical scavenger shown to prevent radiation-induced in vitro cell damage and protect non-irradiated surrounding cells. An important feature of A1M is that, following distribution to the blood, it is equilibrated to the extravascular compartments and filtrated in the kidneys. Aiming at developing renal protection against toxic side-effects of PRRT, we have characterized the pharmacokinetics and biodistribution of intravenously (i.v.) injected (125)I- and non-labelled recombinant human A1M and the (111)In- and fluorescence-labelled somatostatin analogue octreotide. Both molecules were predominantly localized to the kidneys, displaying a prevailing distribution in the cortex. A maximum of 76% of the injected A1M and 46% of the injected octreotide were present per gram kidney tissue at 10 to 20 minutes, respectively, after i.v. injection. Immunohistochemistry and fluorescence microscopy revealed a dominating co-existence of the two substances in proximal tubules, with a cellular co-localization in the epithelial cells. Importantly, analysis of kidney extracts displayed an intact, full-length A1M at least up to 60 minutes post-injection (p.i.). In summary, the results show a highly similar pharmacokinetics and biodistribution of A1M and octreotide, thus enabling the use of A1M to protect the kidneys tissue during PRRT.

Purpose: The most commonly used technology currently used for autoradiography is storage phosphor screens, which has many benefits such as a large field of view but lacks particle-counting detection of the time and energy of each detected radionuclide decay. A number of alternative designs, using either solid state or scintillator detectors, have been developed to address these issues. The aim of this study is to characterize the imaging performance of one such instrument, a double-sided silicon strip detector (DSSD) system for digital autoradiography. A novel aspect of this work is that the instrument, in contrast to previous prototype systems using the same detector type, provides the ability for user accessible imaging with higher throughput. Studies were performed to compare its spatial resolution to that of storage phosphor screens and test the implementation of multiradionuclide ex vivo imaging in a mouse preclinical animal study., Methods: Detector background counts were determined by measuring a nonradioactive sample slide for 52 h. Energy spectra and detection efficiency were measured for seven commonly used radionuclides under representative conditions for tissue imaging. System dead time was measured by imaging (18)F samples of at least 5 kBq and studying the changes in count rate over time. A line source of (58)Co was manufactured by irradiating a 10 μm nickel wire with fast neutrons in a research reactor. Samples of this wire were imaged in both the DSSD and storage phosphor screen systems and the full width at half maximum (FWHM) measured for the line profiles. Multiradionuclide imaging was employed in a two animal study to examine the intratumoral distribution of a (125)I-labeled monoclonal antibody and a (131)I-labeled engineered fragment (diabody) injected in the same mouse, both targeting carcinoembryonic antigen., Results: Detector background was 1.81 × 10(-6) counts per second per 50 × 50 μm pixel. Energy spectra and detection efficiency were successfully measured for seven radionuclides. The system dead time was measured to be 59 μs, and FWHM for a (58)Co line source was 154 ± 14 μm for the DSSD system and 343 ± 15 μm for the storage phosphor system. Separation of the contributions from (125)I and (131)I was performed on autoradiography images of tumor sections., Conclusions: This study has shown that a DSSD system can be beneficially applied for digital autoradiography with simultaneous multiradionuclide imaging capability. The system has a low background signal, ability to image both low and high activity samples, and a good energy resolution.