Quantitative MRI to Characterize Hypoxic Tumors in Comparison to FMISO PET/CT for Radiotherapy in Oropharynx Cancers

Intratumoral hypoxia is associated with a poor prognosis and poor response to treatment in head and neck cancers. Its identification would allow for increasing the radiation dose to hypoxic tumor subvolumes. 18F-FMISO PET imaging is the gold standard; however, quantitative multiparametric MRI could show the presence of intratumoral hypoxia. Thus, 16 patients were prospectively included and underwent 18F-FDG PET/CT, 18F-FMISO PET/CT, and multiparametric quantitative MRI (DCE, diffusion and relaxometry T1 and T2 techniques) in the same position before treatment. PET and MRI sub-volumes were segmented and classified as hypoxic or non-hypoxic volumes to compare quantitative MRI parameters between normoxic and hypoxic volumes. In total, 13 patients had hypoxic lesions. The Dice, Jaccard, and overlap fraction similarity indices were 0.43, 0.28, and 0.71, respectively, between the FDG PET and MRI-measured lesion volumes, showing that the FDG PET tumor volume is partially contained within the MRI tumor volume. The results showed significant differences in the parameters of SUV in FDG and FMISO PET between patients with and without measurable hypoxic lesions. The quantitative MRI parameters of ADC, T1 max mapping and T2 max mapping were different between hypoxic and normoxic subvolumes. Quantitative MRI, based on free water diffusion and T1 and T2 mapping, seems to be able to identify intra-tumoral hypoxic sub-volumes for additional radiotherapy doses.

Advances in PET and MRI imaging of tumor hypoxia

Tumor hypoxia is a complex and evolving phenomenon both in time and space. Molecular imaging allows to approach these variations, but the tracers used have their own limitations. PET imaging has the disadvantage of low resolution and must take into account molecular biodistribution, but has the advantage of high targeting accuracy. The relationship between the signal in MRI imaging and oxygen is complex but hopefully it would lead to the detection of truly oxygen-depleted tissue. Different ways of imaging hypoxia are discussed in this review, with nuclear medicine tracers such as [¹⁸F]-FMISO, [¹⁸F]-FAZA, or [⁶⁴Cu]-ATSM but also with MRI techniques such as perfusion imaging, diffusion MRI or oxygen-enhanced MRI. Hypoxia is a pejorative factor regarding aggressiveness, tumor dissemination and resistance to treatments. Therefore, having accurate tools is particularly important.

Comparison of Hypermetabolic and Hypoxic Volumes Delineated on [18F]FDG and [18F]Fluoromisonidazole PET/CT in Non-small-cell Lung Cancer Patients

PURPOSE

The high rates of failure in the radiotherapy target volume suggest that patients with stage II or III non-small-cell lung cancer (NSCLC) should receive an increased total dose of radiotherapy. 2-Deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) and [¹⁸F]fluoromisonidazole ([¹⁸F]FMISO) (hypoxia) uptake on pre-radiotherapy positron emission tomography (PET)/X-ray computed tomography (CT) have been independently reported to identify intratumor subvolumes at higher risk of relapse after radiotherapy. We have compared the [¹⁸F]FDG and [¹⁸F]FMISO volumes defined by PET/CT in NSCLC patients included in a prospective study.

PROCEDURES

Thirty-four patients with non-resectable lung cancer underwent [¹⁸F]FDG and [¹⁸F]FMISO PET/CT before (pre-RT) and during radiotherapy (around 42 Gy, per-RT). The criteria were to delineate 40 % and 90 % SUVmax thresholds on [¹⁸F]FDG PET/CT (metabolic volumes), and SUV > 1.4 on pre-RT [¹⁸F]FMISO PET/CT (hypoxic volume). The functional volumes were delineated within the tumor volume as defined on co-registered CTs.

RESULTS

The mean pre-RT and per-RT [¹⁸F]FDG volumes were not statistically different (30.4 cc vs 22.2; P = 0.12). The mean pre-RT SUVmax [¹⁸F]FDG was higher than per-RT SUVmax (12.7 vs 6.5; P < 0.0001). The mean [¹⁸F]FMISO SUVmax and volumes were 2.7 and 1.37 cc, respectively. Volume-based analysis showed good overlap between [¹⁸F]FDG and [¹⁸F]FMISO for all methods of segmentation but a poor correlation for Jaccard or Dice Indices (DI). The DI maximum was 0.45 for a threshold at 40 or 50 %.

CONCLUSION

The correlation between [¹⁸F]FDG and [¹⁸F]FMISO uptake is low in NSCLC, making it possible to envisage different management strategies as the studies in progress show.

Targeting the Urotensin II/UT G Protein-Coupled Receptor to Counteract Angiogenesis and Mesenchymal Hypoxia/Necrosis in Glioblastoma

Glioblastomas (GBMs) are the most common primary brain tumors characterized by strong invasiveness and angiogenesis. GBM cells and microenvironment secrete angiogenic factors and also express chemoattractant G protein-coupled receptors (GPCRs) to their advantage. We investigated the role of the vasoactive peptide urotensin II (UII) and its receptor UT on GBM angiogenesis and tested potential ligand/therapeutic options based on this system. On glioma patient samples, the expression of UII and UT increased with the grade with marked expression in the vascular and peri-necrotic mesenchymal hypoxic areas being correlated with vascular density. In vitro human UII stimulated human endothelial HUV-EC-C and hCMEC/D3 cell motility and tubulogenesis. In mouse-transplanted Matrigel sponges, mouse (mUII) and human UII markedly stimulated invasion by macrophages, endothelial, and smooth muscle cells. In U87 GBM xenografts expressing UII and UT in the glial and vascular compartments, UII accelerated tumor development, favored hypoxia and necrosis associated with increased proliferation (Ki67), and induced metalloproteinase (MMP)-2 and -9 expression in Nude mice. UII also promoted a “tortuous” vascular collagen-IV expressing network and integrin expression mainly in the vascular compartment. GBM angiogenesis and integrin αvβ3 were confirmed by in vivo^99mTc-RGD tracer imaging and tumoral capture in the non-necrotic area of U87 xenografts in Nude mice. Peptide analogs of UII and UT antagonist were also tested as potential tumor repressor. Urotensin II-related peptide URP inhibited angiogenesis in vitro and failed to attract vascular and inflammatory components in Matrigel in vivo. Interestingly, the UT antagonist/biased ligand urantide and the non-peptide UT antagonist palosuran prevented UII-induced tubulogenesis in vitro and significantly delayed tumor growth in vivo. Urantide drastically prevented endogenous and UII-induced GBM angiogenesis, MMP, and integrin activations, associated with GBM tumoral growth. These findings show that UII induces GBM aggressiveness with necrosis and angiogenesis through integrin activation, a mesenchymal behavior that can be targeted by UT biased ligands/antagonists.

The added value of clinical radiopharmacists in nuclear medicine: The example of glomerular filtration rate assessment in kidney donors

WHAT IS KNOWN AND OBJECTIVES

In Europe, the pharmaceutical supply of chromium-51 has been stopped. However, this isotope is necessary for the evaluation of glomerular filtration rates. It is possible to replace it with technetium-99m, but the validation of this change in the measurement method must be carried out.

METHODS

A retrospective analysis of chromium-51 data from January 2018 to January 2019 was performed, followed by a study from January 2019 to January 2020 using the technetium tracer. The patients were different in the both study groups, and none had an eGFR below 50 mL min^-1 . A cost analysis was performed. Patient exposure to ionizing radiation was studied for both methods.

RESULTS AND DISCUSSION

Seventy-eight patients were included in the study. In total, 42 EDTA-⁵¹ Cr and 36 DTPA-^99m Tc examinations were conducted and compared. There were no significant differences between the methods used to assess renal function (P = .351). The results of cost analysis and patient radiation exposure were in favour of DTPA-^99m Tc examinations.

WHAT IS NEW AND CONCLUSION

Within the limitations of a retrospective study of two patient cohorts, there was no significant difference between the results obtained with chromium-51 and technetium-99m tracers. In addition, with the use of DTPA-^99m Tc, operating costs and patient exposure to ionizing radiation were reduced, and clinical activity was maintained for the patients' benefit. Radiopharmacists are able to react quickly to supply contingencies, reduce operating costs and maintain the quality of medical examinations.

Benefits of positron emission tomography scans for the evaluation of radiotherapy

The assessment of tumour response during and after radiotherapy determines the subsequent management of patients (adaptation of treatment plan, monitoring, adjuvant treatment, rescue treatment or palliative care). In addition to its role in extension assessment and therapeutic planning, positron emission tomography combined with computed tomography provides useful functional information for the evaluation of tumour response. The objective of this article is to review published data on positron emission tomography combined with computed tomography as a tool for evaluating external radiotherapy for cancers. Data on positron emission tomography combined with computed tomography scans acquired at different times (during, after initial and after definitive [chemo-]radiotherapy, during post-treatment follow-up) in solid tumours (lung, head and neck, cervix, oesophagus, prostate and rectum) were collected and analysed. Recent recommendations of the National Comprehensive Cancer Network are also reported. Positron emission tomography combined with computed tomography with (¹⁸F)-labelled fluorodeoxyglucose has a well-established role in clinical routine after chemoradiotherapy for locally advanced head and neck cancers, particularly to limit the number of neck lymph node dissection. This imaging modality also has a place for the evaluation of initial chemoradiotherapy of oesophageal cancer, including the detection of distant metastases, and for the post-therapeutic evaluation of cervical cancer. Several radiotracers for positron emission tomography combined with computed tomography, such as choline, are also recommended for patients with prostate cancer with biochemical failure. (¹⁸F)-fluorodeoxyglucose positron emission tomography combined with computed tomography is optional in many other circumstances and its clinical benefits, possibly in combination with MRI, to assess response to radiotherapy remain a very active area of research.

[Discontinuation of Chromium-51 for clinical use: What are the possible alternatives for radiopharmacies and nuclear medicine departments?]

OBJECTIVES

Last October, the nuclear medicine departments were informed of the closure of the chromium-51 production line for clinical use. This radionuclide has different diagnostic indications in nephrology and hematology. It was therefore essential to set up alternative exploration protocols to overcome this production stoppage.

METHODS

Chromium-51 EDTA has been replaced by technetium-99m DTPA for the determination of glomerular filtration rates. Sodium chromate was substituted by sodium pertechnetate for the determination of globular volumes. A retrospective analysis of the chromium-51 data was performed followed by a prospective study, from January to December 2019 for technetium tracers.

RESULTS

One hundred and forty-four patients were included in the study. Forty-two EDTA-⁵¹Cr and 30 DTPA-^99mTc exams were conducted and compared. There were no significant differences between the methods used to assess renal function (P=0.355). For the determination of blood cell and plasma volumes, 47 tests with ⁵¹Cr and ¹²⁵I and 25 tests with ^99mTc and ¹²⁵I were performed and compared. There were no significant differences in the determination of total (P=0.325) and globular (P=0.148) volumes.

CONCLUSIONS

The study carried out shows that there is no significant difference between the results obtained with chromium-51 and technetium tracers. As a result, clinical activity was maintained in good conditions.

Development of Novel 111-In-Labelled DOTA Urotensin II Analogues for Targeting the UT Receptor Overexpressed in Solid Tumours

Overexpression of G protein-coupled receptors (GPCRs) in tumours is widely used to develop GPCR-targeting radioligands for solid tumour imaging in the context of diagnosis and even treatment. The human vasoactive neuropeptide urotensin II (hUII), which shares structural analogies with somatostatin, interacts with a single high affinity GPCR named UT. High expression of UT has been reported in several types of human solid tumours from lung, gut, prostate, or breast, suggesting that UT is a valuable novel target to design radiolabelled hUII analogues for cancer diagnosis. In this study, two original urotensinergic analogues were first conjugated to a DOTA chelator via an aminohexanoic acid (Ahx) hydrocarbon linker and then -hUII and DOTA-urantide, complexed to the radioactive metal indium isotope to successfully lead to radiolabelled DOTA-Ahx-hUII and DOTA-Ahx-urantide. The ¹¹¹In-DOTA-hUII in human plasma revealed that only 30% of the radioligand was degraded after a 3-h period. DOTA-hUII and DOTA-urantide exhibited similar binding affinities as native peptides and relayed calcium mobilization in HEK293 cells expressing recombinant human UT. DOTA-hUII, not DOTA-urantide, was able to promote UT internalization in UT-expressing HEK293 cells, thus indicating that radiolabelled ¹¹¹In-DOTA-hUII would allow sufficient retention of radioactivity within tumour cells or radiolabelled DOTA-urantide may lead to a persistent binding on UT at the plasma membrane. The potential of these radioligands as candidates to target UT was investigated in adenocarcinoma. We showed that hUII stimulated the migration and proliferation of both human lung A549 and colorectal DLD-1 adenocarcinoma cell lines endogenously expressing UT. In vivo intravenous injection of ¹¹¹In-DOTA-hUII in C57BL/6 mice revealed modest organ signals, with important retention in kidney. ¹¹¹In-DOTA-hUII or ¹¹¹In-DOTA-urantide were also injected in nude mice bearing heterotopic xenografts of lung A549 cells or colorectal DLD-1 cells both expressing UT. The observed significant renal uptake and low tumour/muscle ratio (around 2.5) suggest fast tracer clearance from the organism. Together, DOTA-hUII and DOTA-urantide were successfully radiolabelled with ¹¹¹Indium, the first one functioning as a UT agonist and the second one as a UT-biased ligand/antagonist. To allow tumour-specific targeting and prolong body distribution in preclinical models bearing some solid tumours, these radiolabelled urotensinergic analogues should be optimized for being used as potential molecular tools for diagnosis imaging or even treatment tools.

Immunotherapy by Immune Checkpoint Inhibitors and Nuclear Medicine Imaging: Current and Future Applications

Immunotherapy by using immune checkpoint inhibitors is a revolutionary development in oncology. Medical imaging is also impacted by this new therapy, particularly nuclear medicine imaging (also called radionuclide imaging), which uses radioactive tracers to visualize metabolic functions. Our aim was to review the current applications of nuclear medicine imaging in immunotherapy, along with their limitations, and the perspectives offered by this imaging modality. Method: Articles describing the use of radionuclide imaging in immunotherapy were researched using PubMed by April 2019 and analyzed. Results: More than 5000 articles were analyzed, and nearly 100 of them were retained. Radionuclide imaging, notably 18F-FDG PET/CT, already has a major role in many cancers for pre-therapeutic and therapeutic evaluation, diagnoses of adverse effects, called immune-related adverse events (IrAE), and end-of-treatment evaluations. However, these current applications can be hindered by immunotherapy, notably due to atypical response patterns such as pseudoprogression, which is defined as an increase in the size of lesions, or the visualization of new lesions, followed by a response, and hyperprogression, which is an accelerated tumor growth rate after starting treatment. To overcome these difficulties, new opportunities are offered, particularly therapeutic evaluation criteria adapted to immunotherapy and immuno-PET allowing us to predict responses to immunotherapy. Moreover, some new technological solutions are also promising, such as radiomic analyses and body composition on associated anatomical images. However, more research has to be done, notably for the diagnosis of hyperprogression and pseudoprogression. Conclusion: Immunotherapy, by its major impact on cancer and by the new patterns generated on images, is revolutionary in the field of medical images. Nuclear medicine imaging is already established and will be able to help meet new challenges through its plasticity.

Radiotherapy boost in patients with hypoxic lesions identified by 18F-FMISO PET/CT in non-small-cell lung carcinoma: can we expect a better survival outcome without toxicity? [RTEP5 long-term follow-up]

PURPOSE

Chemoradiotherapy is the reference curative-intent treatment for nonresectable locally advanced non-small-cell lung carcinoma (NSCLC), with unsatisfactory survival, partially due to radiation resistance in hypoxic tissues. The objective was to update survival and toxicity at 3 years following radiotherapy boost to hypoxic tumours in NSCLC patients treated with curative-intent chemoradiotherapy.

METHODS

This was an open-label, nonrandomized, multicentre, phase II clinical trial. ¹⁸F-Fluoromisonidazole (¹⁸F-FMISO) PET/CT was used to determine the hypoxic profile of the patients. ¹⁸F-FMISO-positive patients and those without organ-at-risk constraints received a radiotherapy boost (70-84 Gy); the others received standard radiotherapy (66 Gy). Overall survival (OS), progression-free survival (PFS) and safety were assessed.

RESULTS

A total of 54 patients were evaluated. OS and PFS rates at 3 years were 48.5% and 28.8%, respectively. The median OS in the ¹⁸F-FMISO-positive patients was 25.8 months and was not reached in the ¹⁸F-FMISO-negative patients (p = 0.01). A difference between the groups was also observed for PFS (12 months vs. 26.2 months, p = 0.048). In ¹⁸F-FMISO-positive patients, no difference was observed in OS in relation to dose, probably because of the small sample size (p = 0.30). However, the median OS seemed to be in favour of patients who received the radiotherapy boost (26.5 vs. 15.3 months, p = 0.71). In patients who received the radiotherapy boost, no significant late toxicities were observed.

CONCLUSION

¹⁸F-FMISO uptake in NSCLC patients is strongly associated with features indicating a poor prognosis. In ¹⁸F-FMISO-positive patients, the radiotherapy boost seemed to improve the OS by 11.2 months. A further clinical trial is needed to investigate the efficacy of a radiotherapy boost in patients with hypoxic tumours.

Real-time molecular optical micro-imaging of EGFR mutations using a fluorescent erlotinib based tracer

BACKGROUND

EGFR mutations are routinely explored in lung adenocarcinoma by sequencing tumoral DNA. The aim of this study was to evaluate a fluorescent-labelled erlotinib based theranostic agent for the molecular imaging of mutated EGFR tumours in vitro and ex vivo using a mice xenograft model and fibred confocal fluorescence microscopy (FCFM).

METHODS

The fluorescent tracer was synthesized in our laboratory by addition of fluorescein to an erlotinib molecule. Three human adenocarcinoma cell lines with mutated EGFR (HCC827, H1975 and H1650) and one with wild-type EGFR (A549) were xenografted on 35 Nude mice. MTT viability assay was performed after exposure to our tracer. In vitro imaging was performed at 1 μM tracer solution, and ex vivo imaging was performed on fresh tumours excised from mice and exposed to a 1 μM tracer solution in PBS for 1 h. Real-time molecular imaging was performed using FCFM and median fluorescence intensity (MFI) was recorded for each experiment.

RESULTS

MTT viability assay confirmed that addition of fluorescein to erlotinib did not suppress the cytotoxic of erlotinib on tumoral cells. In vitro FCFM imaging showed that our tracer was able to distinguish cell lines with mutated EGFR from those lines with wild-type EGFR (p < 0.001). Ex vivo FCFM imaging of xenografts with mutated EGFR had a significantly higher MFI than wild-type (p < 0.001). At a cut-off value of 354 Arbitrary Units, MFI of our tracer had a sensitivity of 100% and a specificity of 96.3% for identifying mutated EGFR tumours.

CONCLUSION

Real time molecular imaging using fluorescent erlotinib is able to identify ex vivo tumours with EGFR mutations.

FDG and FMISO PET-guided dose escalation with intensity-modulated radiotherapy in lung cancer

Background

Concomitant chemo-radiotherapy is the reference treatment for non-resectable locally-advanced Non-Small Cell Lung Cancer (NSCLC). Increasing radiotherapy total dose in the whole tumour volume has been shown to be deleterious. Functional imaging with positron emission tomography (PET/CT) offers the potential to identify smaller and biologically meaningful target volumes that could be irradiated with larger doses without compromising Organs At Risk (OAR) tolerance. This study investigated four scenarios, based on ¹⁸FDG and ¹⁸F-miso PET/CT, to delineate the target volumes and derive radiotherapy plans delivering up to 74Gy.

Method

Twenty-one NSCLC patients, selected from a prospective phase II trial, had ¹⁸FDG- and ¹⁸F-miso PET/CT before the start of radiotherapy and ¹⁸FDG PET/CT during the radiotherapy (42Gy). The plans were based planned on a standard plan delivering 66 Gy (plan 1) and on three different boost strategies to deliver 74Gy total dose in pre-treatment ¹⁸FDG hotspot (70% of SUV_max) (plan 2), pre-treatment ¹⁸F-miso target (SUV_max > 1.4) (plan 3) and per-treatment ¹⁸FDG residual (40% of SUV_max). (plan 4).

Results

The mean target volumes were 4.8 cc (± 1.1) for ¹⁸FDG hotspot, 38.9 cc (± 14.5) for ¹⁸F-miso and 36.0 cc (± 10.1) for per-treatment ¹⁸FDG. In standard plan (66 Gy), the mean dose covering 95% of the PTV (D95%) were 66.5 (± 0.33), 66.1 (± 0.32) and 66.1 (± 0.32) Gy for ¹⁸FDG hotspot, ¹⁸F-miso and per-treatment ¹⁸FDG. In scenario 2, the mean D95% was 72.5 (± 0.25) Gy in ¹⁸FDG hotspot versus 67.9 (± 0.49) and 67.9 Gy (± 0.52) in ¹⁸F-miso and per-treatment ¹⁸FDG, respectively. In scenario 3, the mean D95% was 72.2 (± 0.27) Gy to ¹⁸F-miso versus 70.4 (± 0.74) and 69.5Gy (± 0.74) for ¹⁸FDG hotspot and per-treatment ¹⁸FDG, respectively. In scenario 4, the mean D95% was 73.1 (± 0.3) Gy to ¹⁸FDG per-treatment versus 71.9 (± 0.61) and 69.8 (± 0.61) Gy for ¹⁸FDG hotspot and ¹⁸F-miso, respectively. The dose/volume constraints to OARs were matched in all scenarios.

Conclusion

Escalated doses can be selectively planned in NSCLC target volumes delineated on ¹⁸FDG and ¹⁸F-miso PET/CT functional images. The most relevant strategy should be investigated in clinical trials.

Trial registration

(RTEP5, NCT01576796, registered 15 june 2012)

In- and ex-vivo molecular imaging of apoptosis to assess sensitivity of non-small cell lung cancer to EGFR inhibitors using probe-based confocal laser endomicroscopy

BACKGROUND

Prediction of treatment outcome of non-small cell lung cancer (NSCLC) with EGFR inhibitors on the basis of the genetic analysis of the tumor can be incorrect in case of rare or complex mutations, bypass molecular activation pathways, or pharmacodynamic variations. The aim of this study was to develop an ex vivo and in vivo real-time quantitative imaging test for EGFR inhibitors sensitivity assessment.

METHODS

Erlotinib resistant (A549, H460, H1975), insensitive (H1650) and hypersensitive (HCC827) cell lines were injected subcutaneously in Nude mice. Tumor xenografts from mice treated with Erlotinib were imaged ex vivo and in vivo using probe-based confocal laser endomicroscopy (pCLE) and NucView 488 Caspase 3 substrate, a fluorescent probe specific for the activated caspase 3.

RESULTS

Assessment of apoptosis at 24h post treatment, both ex vivo in explanted tumor xenografts and in vivo, showed a significant difference between resistant cell lines (A549, H460 and H1975) and insensitive (H1650) or hypersensitive (HCC827) ones (p<0.05 for ex vivo imaging, p≤0.02 for in vivo imaging). There was also a significant difference between insensitive and hypersensitive cell lines, both ex vivo (p<0.05) and in vivo (p = 0.01).

CONCLUSION

Real-time in vivo and ex vivo assessment of apoptosis using pCLE differentiates resistant from sensitive NSCLC xenografts to Erlotinib.

Phase II Study of a Radiotherapy Total Dose Increase in Hypoxic Lesions Identified by 18F-Misonidazole PET/CT in Patients with Non-Small Cell Lung Carcinoma (RTEP5 Study)

See an invited perspective on this article on page 1043.This multicenter phase II study investigated a selective radiotherapy dose increase to tumor areas with significant ¹⁸F-misonidazole (¹⁸F-FMISO) uptake in patients with non-small cell lung carcinoma (NSCLC). Methods: Eligible patients had locally advanced NSCLC and no contraindication to concomitant chemoradiotherapy. The ¹⁸F-FMISO uptake on PET/CT was assessed by trained experts. If there was no uptake, 66 Gy were delivered. In ¹⁸F-FMISO-positive patients, the contours of the hypoxic area were transferred to the radiation oncologist. It was necessary for the radiotherapy dose to be as high as possible while fulfilling dose-limiting constraints for the spinal cord and lungs. The primary endpoint was tumor response (complete response plus partial response) at 3 mo. The secondary endpoints were toxicity, disease-free survival (DFS), and overall survival at 1 y. The target sample size was set to demonstrate a response rate of 40% or more (bilateral α = 0.05, power 1-β = 0.95). Results: Seventy-nine patients were preincluded, 54 were included, and 34 were ¹⁸F-FMISO-positive, 24 of whom received escalated doses of up to 86 Gy. The response rate at 3 mo was 31 of 54 (57%; 95% confidence interval [CI], 43%-71%) using RECIST 1.1 (17/34 responders in the ¹⁸F-FMISO-positive group). DFS and overall survival at 1 y were 0.86 (95% CI, 0.77-0.96) and 0.63 (95% CI, 0.49-0.74), respectively. DFS was longer in the ¹⁸F-FMISO-negative patients (P = 0.004). The radiotherapy dose was not associated with DFS when adjusting for the ¹⁸F-FMISO status. One toxic death (66 Gy) and 1 case of grade 4 pneumonitis (>66 Gy) were reported. Conclusion: Our approach results in a response rate of 40% or more, with acceptable toxicity. ¹⁸F-FMISO uptake in NSCLC patients is strongly associated with poor prognosis features that could not be reversed by radiotherapy doses up to 86 Gy.

SPECT-computed tomography in rats with TNBS-induced colitis: A first step toward functional imaging

AIM

To assess the feasibility of SPECT-computed tomography (CT) in rats with trinitrobenzene sulfonic acid (TNBS)-induced acute colitis and confront it with model inflammatory characteristics.

METHODS

Colitis was induced in Sprague-Dawley rats by intrarectal injection of TNBS (n = 10) while controls received vehicle (n = 10). SPECT-CT with intravenous injection of 10 MBq of 67Ga-Citrate was performed at day 2. SPECT-CT criteria were colon wall thickness and maximal wall signal intensity. Laboratory parameters were assessed: colon weight:length ratio, colon cyclooxygenase-2 expression by western blot and histological inflammatory score.

RESULTS

Colon weight/length ratio, colon COX-2 expression and histological inflammatory score were significantly higher in the TNBS group than in the control group (P = 0.0296, P < 0.0001, P = 0.0007 respectively). Pixel max tend to be higher in the TNBS group than in the control group but did not reach statistical significance (P = 0.0662). Maximal thickness is significantly increased in the TNBS group compared to the control group (P = 0.0016) while colon diameter is not (P = 0.1904). Maximal thickness and colon diameter were correlated to colon COX-2 expression (P = 0.0093, P = 0.009 respectively) while pixel max was not (P = 0.22). Maximal thickness was significantly increased when inflammation was histologically observed (P = 0.0043) while pixel max and colon diameter did not (P = 0.2452, P = 0.3541, respectively).

CONCLUSION

SPECT-CT is feasible and easily distinguished control from colitic rats.

Physicochemical stability of oxycodone-ketamine solutions in polypropylene syringe and polyvinyl chloride bag for patient-controlled analgesia use

Objectives

The study evaluated the stability of three combinations of oxycodone and ketamine diluted in normal saline (NS) after storage for 7 days at 23°C and exposed to light.

Methods

The stability of three mixtures of oxycodone and ketamine (oxycodone 0.4 mg/mL+ketamine 40 mg/mL, oxycodone 10 mg/mL+ketamine 0.1 mg/mL and oxycodone 10 mg/mL+ketamine 40 mg/mL) in NS stored in a polypropylene syringe and a polyvinyl chloride (PVC) bag was studied. The physical characteristics, including pH, colour and precipitation, were evaluated. The samples were analysed in triplicate by a stability-indicating high-performance liquid chromatography method.

Results

There was no significant change in the pH values of any solution. No precipitation or change in colour was observed. All formulations maintained more than 95% of the initial concentration of each drug on day 7. No trace of degradation products was detected.

Conclusions

Ketamine (0.1-40 mg/mL) combined with oxycodone (0.4-10 mg/mL) is physically compatible and chemically stable for 7 days when diluted with NS, packaged in polypropylene syringe or PVC bag and stored at 23°C.

Photodynamic therapy using methylene blue in lung adenocarcinoma xenograft and hamster cheek pouch induced squamous cell carcinoma

BACKGROUND

Photodynamic therapy (PDT) is used to treat early proximal bronchial cancer during a flexible bronchoscopy. The technique relies on the excitation of a photosensitizer by an appropriate wavelength, which is delivered into the bronchus in close contact with the tumor.

OBJECTIVE

To assess methylene blue (MB) as a PDT agent for the treatment of respiratory tract cancer in animal models.

METHODS

MB-induced PDT was performed on 7 subcutaneous NCI-H460 lung adenocarcinoma xenografts in nude mice and 9 induced squamous cell cancer in the hamster cheek pouch model. In mice, PDT was carried out on right-sided tumors after intratumoral injection of methylene blue 1% (w/v) and illumination at 630nm at 200J/cm (Diomed PDT 630), with the left tumor used as control (illumination alone or MB alone). The tumoral volume was assessed before and 15 days after PDT.

RESULTS

Fourteen xenografts were treated in mice, including seven treated with MB-PDT, producing a 52% mean tumor volume regression (1568mm(3)vs. 544mm(3)) compared to seven control cases in which tumor volume increased (p=0.007; Mann-Whitney test). Nine cheek pouch induced carcinomas were treated in the hamster group, with a mean volume decrease of 85.8% (from 44.8% to 100%) (initial mean volume=210mm(3)vs. post PDT mean volume=97mm(3)). Histology analysis showed 4/9 complete responses.

CONCLUSION

Intratumoral MB appears efficient as PDT agent for cancer treatment in animal models. Further studies are needed to assess the safety and efficacy of MB-associated PDT for the treatment of lung cancer in humans.

Dihydroquinoline Carbamate Derivatives as "Bio-oxidizable" Prodrugs for Brain Delivery of Acetylcholinesterase Inhibitors: [¹¹C] Radiosynthesis and Biological Evaluation

With the aim of improving the efficiency of marketed acetylcholinesterase (AChE) inhibitors in the symptomatic treatment of Alzheimer's disease, plagued by adverse effects arising from peripheral cholinergic activation, this work reports a biological evaluation of new central AChE inhibitors based on an original "bio-oxidizable" prodrug strategy. After peripheral injection of the prodrug 1a [IC50 > 1 mM (hAChE)] in mice, monitoring markers of central and peripheral cholinergic activation provided in vivo proof-of-concept for brain delivery of the drug 2a [IC50 = 20 nM (hAChE)] through central redox activation of 1a. Interestingly, peripheral cholinergic activation has been shown to be limited in time, likely due to the presence of a permanent positive charge in 2a promoting rapid elimination of the AChE inhibitor from the circulation of mice. To support these assumptions, the radiosynthesis with carbon-11 of prodrug 1a was developed for additional ex vivo studies in rats. Whole-body biodistribution of radioactivity revealed high accumulation in excretory organs along with moderate but rapid brain uptake. Radio-HPLC analyses of brain samples confirm rapid CNS penetration of [(11)C]1a, while identification of [(11)C]2a and [(11)C]3a both accounts for central redox activation of 1a and pseudoirreversible inhibition of AChE, respectively. Finally, Caco-2 permeability assays predicted metabolite 3a as a substrate for efflux transporters (P-gp inter alia), suggesting that metabolite 3a might possibly be actively transported out of the brain. Overall, a large body of evidence from in vivo and ex vivo studies on small animals has been collected to validate this "bio-oxidizable" prodrug approach, emerging as a very promising strategy in the rational design of selective central AChE inhibitors.

Synthesis of new 18F-radiolabeled silicon-based nitroimidazole compounds

The syntheses of new nitroimidazole compounds using silicon-[(18)F]fluorine chemistry for the potential detection of tumor hypoxia are described. [(18)F]silicon-based compounds were synthesized by coupling 2-nitroimidazole with silyldinaphtyl or silylphenyldi-tert-butyl groups and labeled by fluorolysis or isotopic exchange. Dinaphtyl compounds (6, 10) were labeled in 56-71% yield with a specific activity of 45 GBq/μmol, however these compounds ([(18)F]7 and [(18)F]11) were not stable in plasma. Phenyldi-tert-butyl compounds were labeled in 70% yield with a specific activity of 3 GBq/μmol by isotopic exchange, or in 81% yield by fluorolysis of siloxanes with a specific activity of 45 GBq/μmol. The labeled compound [(18)F]18 was stable in plasma and excreted by the liver and kidneys in vivo. In conclusion, the fluorosilylphenyldi-tert-butyl (SiFA) group is more stable in plasma than fluorosilyldiphenyl moiety. Thus, compound [(18)F]18 is suitable for further in vivo assessments.

⁹⁹mTc-(Me)FGCDEVD, a potential tracer for apoptosis detection

(Me)FGC(Bz)DEVD was radiolabeled with technetium-99m in high yield. This tracer was preferentially accumulated in apoptotic cells in the in vitro studies. Tumor uptake occurred in vivo after cisplatin injection due to the apoptosis induction, which not observed in the untreated tumors. Therefore, (99m)Tc-(Me)FGCDEVD is a potential tracer for apoptosis detection.

New huprine derivatives functionalized at position 9 as highly potent acetylcholinesterase inhibitors

A series of 24 huprine derivatives diversely functionalized at position 9 have been synthesized and evaluated for their inhibitory activity against human recombinant acetylcholinesterase (AChE). These derivatives were prepared in one to five steps from huprine 1 bearing an ester function at position 9. Ten analogues (1, 2, 6-9, 13-15, and 23) are active in the low nanomolar range (IC(50) <5 nM), very close to the parent compound huprine X. Compounds 2, 6, and 7 show a very good selectivity for AChE, with AChE inhibitory activities 700-1160-fold higher than those for butyrylcholinesterase (BChE). The inhibitory potency of these compounds decreases with the steric bulk of the substituents at position 9. According to docking simulations, small substituents fit into the acyl-binding pocket, whereas the larger ones stick out of the active site gorge of AChE. Determination of the kinetic parameters of three of the most potent huprines (2, 6, and 7) showed that most of the difference in K(D) is accounted by a decrease in k(on) , which is correlated to the increase of the substituent size. A first in vivo evaluation has been performed in mice for the most active compound 2 (IC(50) =1.1 nM) and showed a rather weak toxicity (LD(50) =40 mg kg(-1) ) and an ability to cross the blood-brain barrier with doses above 15 mg kg(-1).

Simultaneous positron emission tomography (PET) assessment of metabolism with ¹⁸F-fluoro-2-deoxy-d-glucose (FDG), proliferation with ¹⁸F-fluoro-thymidine (FLT), and hypoxia with ¹⁸fluoro-misonidazole (F-miso) before and during radiotherapy in patients with non-small-cell lung cancer (NSCLC): a pilot study

OBJECTIVES

To investigate the changes in tumour proliferation (using FLT), metabolism (using FDG), and hypoxia (using F-miso) during curative (chemo-) radiotherapy (RT) in patients with non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Thirty PET scans were performed in five patients (4 males, 1 female) that had histological proof of NSCLC and were candidates for curative-intent RT. Three PET-CT (Biograph S16, Siemens) scans were performed before (t(0)) and during (around dose 46 Gy, t(46)) RT with minimal intervals of 48 h between each PET-CT scan. The tracers used were (18)fluoro-2deoxyglucose (FDG) for metabolism, (18)fluorothymidine (FLT) for proliferation, and (18)F-misonidasole (F-miso) for hypoxia. The 3 image sets obtained at each time point were co-registered (rigid: n=9, elastic: n=1, Leonardo, TrueD, Siemens) using FDG PET-CT as reference. VOIs were delineated (40% SUV(max) values were used as a threshold) for tumours and lymph nodes on FDG PET-CT, and they were automatically pasted on FLT and F-miso PET-CT images. ANOVA and correlation analyses were used for comparison of SUV(max) values.

RESULTS

Four tumours and twelve nodes were identified on initial FDG PET-CT images. FLT SUV(max) values were significantly lower (p<0.0006) at t(46) in both tumours and nodes. The decrease in FDG SUV(max) values had a trend towards significance (p=0.048). F-Miso SUV(max) values were significantly higher in tumours than in nodes (p=0.02) and did not change during radiotherapy (p=0.39). A significant correlation was observed between FLT and FDG uptake (r=0.56, p<10(-4)) when all data were pooled together, and they remained similar when the before and during RT data were analysed separately. FDG and F-miso uptakes were significantly correlated (r=0.59, p=0.0004) when all data were analysed together. The best fit was obtained after adjusting for lesion type (tumour vs. node). This correlation was observed for the SUV(max) measured during RT (r=0.70, p=0.008) but not for the pre-RT data (r=0.19, p=0.35). The weak correlation between FLT and F-miso uptakes only became significant (r=0.66, p=0.002) when the analysis was restricted to the data acquired during RT.

CONCLUSION

Three different PET acquisitions can be performed quasi-simultaneously (4-7 days) before and during radiotherapy in patients with NSCLC. Our results at 46 Gy suggest that a fast decrease in the proliferation of both tumours and nodes exists during radiotherapy with differences in metabolism (borderline significant decrease) and hypoxia (stable).

αvβ3 imaging can accurately distinguish between mature teratoma and necrosis in 18F-FDG-negative residual masses after treatment of non-seminomatous testicular cancer: a preclinical study

PURPOSE

We assessed whether imaging α(v)β(3) integrin could distinguish mature teratoma from necrosis in human non-seminomatous germ cell tumour (NSGCT) post-chemotherapy residual masses.

METHODS

Human embryonal carcinoma xenografts (six/rat) were untreated (controls) or treated to form mature teratomas with low-dose cisplatin and all-trans retinoic acid (ATRA) over a period of 8 weeks. In another group, necrosis was induced in xenografts with high-dose cisplatin plus etoposide (two cycles). (18)F-Fluorodeoxyglucose ((18)F-FDG) small animal positron emission tomography (SA PET) imaging was performed in three rats (one control and two treated for 4 and 8 weeks with cisplatin+ATRA). Imaging of α(v)β(3) expression was performed in six rats bearing mature teratomas and two rats with necrotic lesions on a microSPECT/CT device after injection of the tracer [(99m)Tc]HYNIC-RGD [6-hydrazinonicotinic acid conjugated to cyclo(Arg-Gly-Asp-D-Phe-Lys)]. Correlative immunohistochemistry studies of human and mouse α(v)β(3) expression were performed.

RESULTS

Cisplatin+ATRA induced differentiation of the xenografts. After 8 weeks, some glandular structures and mesenchymal cells were visible; in contrast, control tumours showed undifferentiated tissues. SA PET imaging showed that mature teratoma had very low avidity for (18)F-FDG [mean standardised uptake value (SUV(mean)) = 0.48 ± 0.05] compared to untreated embryonal carcinoma (SUV(mean) = 0.92 ± 0.13) (p = 0.005). α(v)β(3) imaging accurately distinguished mature teratoma (tumour to muscle ratio = 4.29 ± 1.57) from necrosis (tumour to muscle ratio = 1.3 ± 0.26) (p = 0.0002). Immunohistochemistry studies showed that α(v)β(3) integrin expression was strong in the glandular structures of mature teratoma lesions and negative in host stroma.

CONCLUSION

Imaging α(v)β(3) integrin accurately distinguished mature teratoma from necrosis following cisplatin-based treatment in human NSGCT xenografts.

Synthesis, radiosynthesis and biological evaluation of 1,4-dihydroquinoline derivatives as new carriers for specific brain delivery

In spite of numerous reports dealing with the use of 1,4-dihydropyridines as carriers to deliver biological active compounds to the brain, this chemical delivery system (CDS) suffers from poor stability of the 1,4-dihydropyridine derivatives towards oxidation and hydration reactions seriously limiting further investigations in vivo. In an attempt to overcome these limitations, we report herein the first biological evaluation of more stable annellated NADH models in the quinoline series as relevant neuroactive drug-carrier candidates. The radiolabeled 1,4-dihydroquinoline [(11)C] was prepared to be subsequently peripherally injected in rats. The injected animals were sacrificed and brains were collected. The radioactivity measured in rat brain indicated a rapid penetration of the carrier [(11)C] into the CNS. HPLC analysis of brain homogenates showed that oxidation of [(11)C] into the corresponding quinolinium salt [(11)C] was completed in less than 5 min. An in vivo evaluation in mice is also reported to illustrate the potential of such 1,4-dihydroquinoline derivatives to transport a neuroactive drug in the CNS. For this purpose, gamma-aminobutyric acid (GABA), well known to poorly cross the brain blood barrier (BBB) was connected to this 1,4-dihydroquinoline-type carrier. After i.p. injection of 1,4-dihydroquinoline-GABA derivative in mice, a significant alteration of locomotor activity (LMA) was observed presumably resulting from an enhancement of central GABAergic activity. These encouraging results give strong evidence for the capacity of carrier-GABA derivative to cross the BBB and exert a pharmacological effect on the CNS. This study paves the way for further progress in designing new redox chemical delivery systems.

Solid phase synthesis of a redox delivery system with the aim of targeting peptides into the brain

A solid phase approach for the preparation of peptides attached to a redox chemical delivery system derived from stable annulated NADH models is reported. The synthesis starts with the grafting on a Merrifield resin of quinoline 4b, precursor of the redox carrier. From the resulting quinoline supported resin 4d, the stepwise SPPS of both octapeptide OP (RPGLLDLK) and octadecaneuropeptide ODN (QATVGDVNTDRPGLLDLK), two neuropeptides exhibiting anorexigenic effects, was successfully achieved by conventional methods. Quaternization of the quinoline moiety prior to cleavage of the modified OP and ODN peptides from the resin, led to the expected quinolinium salt 8a and 8b respectively linked to OP or ODN peptides. Finally, the reduction with NaBH4 monitored by UV-vis, provided the desired annulated NADH models as peptides carriers with either the OP (11a,b) or ODN (12a,b) moiety.

Imagined halitosis: a social phobia symptom?

Imagined halitosis is poorly documented in the psychiatric literature. It is perhaps best thought of as a symptom rather than as a specific syndrome (a collection of symptoms that co-vary together). Many of the cases with imagined halitosis described in the literature resemble the psychiatric syndrome of social phobia.

A model for predicting discharge against medical advice from adolescent residential treatment

Characteristics of adolescents discharged from a psychiatric residential treatment center were examined to create a model for predicting patient discharge against medical advice (AMA). Subjects were 81 adolescents in two consecutive cohorts discharged between 1983 and mid-1988 (N = 49 and N = 32). In both groups 41 percent of the discharges were AMA. Logistic regression analysis found that an equation based on three factors--history of juvenile court involvement, unsupportive family attitude toward treatment, and diagnosis of conduct disorder--was 69 percent accurate in predicting discharge status in group 1 and 81 percent accurate in predicting discharge status in group 2. A positive correlation between rates of staff turnover and AMA discharge was noted.