Manual Versus Artificial Intelligence-Based Segmentations as a Pre-processing Step in Whole-body PET Dosimetry Calculations.

PURPOSE: As novel tracers are continuously under development, it is important to obtain reliable radiation dose estimates to optimize the amount of activity that can be administered while keeping radiation burden within acceptable limits. Organ segmentation is required for quantification of specific uptake in organs of interest and whole-body dosimetry but is a time-consuming task which induces high interobserver variability. Therefore, we explored using manual segmentations versus an artificial intelligence (AI)-based automated segmentation tool as a pre-processing step for calculating whole-body effective doses to determine the influence of variability in volumetric whole-organ segmentations on dosimetry. PROCEDURES: PET/CT data of six patients undergoing imaging with 89Zr-labelled pembrolizumab were included. Manual organ segmentations were performed, using in-house developed software, and biodistribution information was obtained. Based on the activity biodistribution information, residence times were calculated. The residence times served as input for OLINDA/EXM version 1.0 (Vanderbilt University, 2003) to calculate the whole-body effective dose (mSv/MBq). Subsequently, organ segmentations were performed using RECOMIA, a cloud-based AI platform for nuclear medicine and radiology research. The workflow for calculating residence times and whole-body effective doses, as described above, was repeated. RESULTS: Data were acquired on days 2, 4, and 7 post-injection, resulting in 18 scans. Overall analysis time per scan was approximately 4 h for manual segmentations compared to ≤ 30 min using AI-based segmentations. Median Jaccard similarity coefficients between manual and AI-based segmentations varied from 0.05 (range 0.00-0.14) for the pancreas to 0.78 (range 0.74-0.82) for the lungs. Whole-body effective doses differed minimally for the six patients with a median difference in received mSv/MBq of 0.52% (range 0.15-1.95%). CONCLUSION: This pilot study suggests that whole-body dosimetry calculations can benefit from fast, automated AI-based whole organ segmentations.

First-in-Human Study of the Biodistribution and Pharmacokinetics of 89Zr-CX-072, a Novel Immunopet Tracer Based on an Anti-PD-L1 Probody.

PURPOSE: CX-072, a PD-L1-targeting Probody therapeutic, is engineered to be activated by tumor proteases that remove a masking peptide. To study effects on biodistribution and pharmacokinetics, we performed 89Zr-CX-072 positron emission tomography (PET) imaging. EXPERIMENTAL DESIGN: Patients received ∼1 mg, 37 MBq 89Zr-CX-072 plus 0, 4, or 9 mg unlabeled CX-072 and PET scans at days 2, 4, and 7. After that, treatment comprised 10 mg/kg CX-072 q2 weeks (n = 7) + 3 mg/kg ipilimumab q3w 4× (n = 1). Normal organ tracer uptake was expressed as standardized uptake value (SUV)mean and tumor uptake as SUVmax. PD-L1 expression was measured immunohistochemically in archival tumor tissue. RESULTS: Three of the eight patients included received 10-mg protein dose resulting in a blood pool mean SUVmean ± SD of 4.27 ± 0.45 on day 4, indicating sufficient available tracer. Tumor uptake was highest at day 7, with a geometric mean SUVmax 5.89 (n = 113) and present in all patients. The median follow-up was 12 weeks (4-76+). One patient experienced stable disease and two patients a partial response. PD-L1 tumor expression was 90% in one patient and ≤1% in the other patients. Mean SUVmean ± SD day 4 at 10 mg in the spleen was 8.56 ± 1.04, bone marrow 2.21 ± 0.46, and liver 4.97 ± 0.97. Four patients out of seven showed uptake in normal lymph nodes and Waldeyer's ring. The tracer was intact in the serum or plasma. CONCLUSIONS: 89Zr-CX-072 showed tumor uptake, even in lesions with ≤1% PD-L1 expression, and modest uptake in normal lymphoid organs, with no unexpected uptake in other healthy tissues.

Comparison of Carboplatin With 5-Fluorouracil vs. Cisplatin as Concomitant Chemoradiotherapy for Locally Advanced Head and Neck Squamous Cell Carcinoma.

Background: Chemoradiotherapy (CRT) including three cycles of cisplatin is considered the standard of care for locally advanced head and neck squamous cell carcinoma (LA-HNSCC). However, around one-third of the patients cannot complete cisplatin because of toxicity. Carboplatin plus 5-fluorouracil (carbo-5FU) is another accepted treatment option with a different toxicity profile. We compared tolerability and efficacy of concomitant carbo-5FU and cisplatin. Patients and Methods: We conducted a retrospective analysis of LA-HNSCC patients treated with CRT in two Dutch cancer centers between 2007 and 2016. All patients received intensity-modulated radiotherapy. One center routinely administered carboplatin 300-350 mg/m2 at day 1, 22, and 43 followed by 5FU 600 mg/m2/day for 96 h. The other center used cisplatin 100 mg/m2 at day 1, 22, and 43. The primary endpoint of this study was chemotherapy completion rate. Secondary endpoints included overall survival (OS), disease-free survival (DFS), locoregional control (LRC) and distant metastasis-free interval (DMFS), toxicity, and unplanned admissions. Results: In the carbo-5FU cohort (n = 211), 60.2% of the patients completed chemotherapy vs. 76.7% (p < 0.001) of the patients in the cisplatin cohort (n = 223). Univariate analysis showed a higher risk of death in the carbo-5FU cohort [hazard ratio (HR) 1.53, 95% CI, 1.09-2.14, p = 0.01] with a 3-year OS of 65.4 vs. 76.5% for cisplatin. OS was independently associated with T and N stage and p16 status, but not with chemotherapy regimen (HR 1.08, 95% CI, 0.76-1.55, p = 0.65). Three-year DFS was 70.0% for carbo-5FU vs. 78.6% for cisplatin (HR 1.37, 95% CI, 0.93-2.01, p = 0.05). A similar outcome was observed for both LRC (HR 1.27, 95% CI, 0.74-2.09, p = 0.4) and DMFS (HR 1.08, 95% CI 0.62-1.90, p = 0.77). The risk of discontinuation for chemotherapy-associated toxicity was higher in the carbo-5FU cohort than in the cisplatin cohort (relative risk = 1.69). Conclusion: LA-HNSCC patients treated with concomitant carbo-5FU completed chemotherapy less frequently than patients treated with cisplatin. Treatment regimen was not an independent prognostic factor for OS.

89Zr-labeled Bispecific T-cell Engager AMG 211 PET Shows AMG 211 Accumulation in CD3-rich Tissues and Clear, Heterogeneous Tumor Uptake.

PURPOSE: Biodistribution of bispecific antibodies in patients is largely unknown. We therefore performed a feasibility study in 9 patients with advanced gastrointestinal adenocarcinomas to explore AMG 211 biodistribution (also known as MEDI-565), an approximately 55 kDa bispecific T-cell engager (BiTE®) directed against carcinoembryonic antigen (CEA) on tumor cells and cluster of differentiation 3 (CD3) on T-cells. EXPERIMENTAL DESIGN: 89Zr-labeled AMG 211 as tracer was administered alone or with cold AMG 211, for PET imaging before and/or during AMG 211 treatment. RESULTS: Before AMG 211 treatment, the optimal imaging dose was 200-µg 89Zr-AMG 211 + 1,800-µg cold AMG 211. At 3 hours, the highest blood pool standardized uptake value (SUV)mean was 4.0, and tracer serum half-life was 3.3 hours. CD3-mediated uptake was clearly observed in CD3-rich lymphoid tissues including spleen and bone marrow (SUVmean 3.2 and 1.8, respectively), and the SUVmean decreased more slowly than in other healthy tissues. 89Zr-AMG 211 remained intact in plasma and was excreted predominantly via the kidneys in degraded forms. Of 43 visible tumor lesions, 37 were PET quantifiable, with a SUVmax of 4.0 [interquartile range (IQR) 2.7-4.4] at 3 hours using the optimal imaging dose. The tracer uptake differed between tumor lesions 5-fold within and 9-fold between patients. During AMG 211 treatment, tracer was present in the blood pool, whereas tumor lesions were not visualized, possibly reflecting target saturation. CONCLUSIONS: This first-in-human study shows high, specific 89Zr-AMG 211 accumulation in CD3-rich lymphoid tissues, as well as a clear, inter- and intraindividual heterogeneous tumor uptake.

89Zr-atezolizumab imaging as a non-invasive approach to assess clinical response to PD-L1 blockade in cancer.

Programmed cell death protein-1/ligand-1 (PD-1/PD-L1) blockade is effective in a subset of patients with several tumor types, but predicting patient benefit using approved diagnostics is inexact, as some patients with PD-L1-negative tumors also show clinical benefit1,2. Moreover, all biopsy-based tests are subject to the errors and limitations of invasive tissue collection3-11. Preclinical studies of positron-emission tomography (PET) imaging with antibodies to PD-L1 suggested that this imaging method might be an approach to selecting patients12,13. Such a technique, however, requires substantial clinical development and validation. Here we present the initial results from a first-in-human study to assess the feasibility of imaging with zirconium-89-labeled atezolizumab (anti-PD-L1), including biodistribution, and secondly test its potential to predict response to PD-L1 blockade (ClinicalTrials.gov identifiers NCT02453984 and NCT02478099). We imaged 22 patients across three tumor types before the start of atezolizumab therapy. The PET signal, a function of tracer exposure and target expression, was high in lymphoid tissues and at sites of inflammation. In tumors, uptake was generally high but heterogeneous, varying within and among lesions, patients, and tumor types. Intriguingly, clinical responses in our patients were better correlated with pretreatment PET signal than with immunohistochemistry- or RNA-sequencing-based predictive biomarkers, encouraging further development of molecular PET imaging for assessment of PD-L1 status and clinical response prediction.

Molecular Imaging in Cancer Drug Development.

Development of new oncology drugs has increased since the improved understanding of cancer's complex biology. The oncology field has become the top therapeutic research area for new drugs. However, only a limited number of drugs entering clinical trials will be approved for use as the standard of care for cancer patients. Molecular imaging is increasingly perceived as a tool to support go/no-go decisions early during drug development. It encompasses a wide range of techniques that include radiolabeling a compound of interest followed by visualization with SPECT or PET. Radiolabeling can be performed using a variety of radionuclides, which are preferably matched to the compound on the basis of size and half-life. Imaging can provide information on drug behavior in vivo, whole-body drug target visualization, and heterogeneity in drug target expression. This review focuses on current applications of molecular imaging in the development of small molecules, antibodies, and antihormonal anticancer drugs.

Theranostics Using Antibodies and Antibody-Related Therapeutics.

In theranostics, radiolabeled compounds are used to determine a treatment strategy by combining therapeutics and diagnostics in the same agent. Monoclonal antibodies (mAbs) and antibody-related therapeutics represent a rapidly expanding group of cancer medicines. Theranostic approaches using these drugs in oncology are particularly interesting because antibodies are designed against specific targets on the tumor cell membrane and immune cells as well as targets in the tumor microenvironment. In addition, these drugs are relatively easy to radiolabel. Noninvasive molecular imaging techniques, such as SPECT and PET, provide information on the whole-body distribution of radiolabeled mAbs and antibody-related therapeutics. Molecular antibody imaging can potentially elucidate drug target expression, tracer uptake in the tumor, tumor saturation, and heterogeneity for these parameters within the tumor. These data can support drug development and may aid in patient stratification and monitoring of the treatment response. Selecting a radionuclide for theranostic purposes generally starts by matching the serum half-life of the mAb or antibody-related therapeutic and the physical half-life of the radionuclide. Furthermore, PET imaging allows better quantification than the SPECT technique. This information has increased interest in theranostics using PET radionuclides with a relatively long physical half-life, such as 89Zr. In this review, we provide an overview of ongoing research on mAbs and antibody-related theranostics in preclinical and clinical oncologic settings. We identified 24 antibodies or antibody-related therapeutics labeled with PET radionuclides for theranostic purposes in patients. For this approach to become integrated in standard care, further standardization with respect to the procedures involved is required.

Meta-analysis and meta-regression of hypothalamic-pituitary-adrenal axis activity in functional somatic disorders.

Dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis is the most investigated biological risk marker in functional somatic disorders (FSDs), such as chronic fatigue syndrome (CFS), fibromyalgia (FM), and irritable bowel syndrome (IBS). Our aim was to assess whether there is an association between basal hypocortisolism and FSD and to identify potential moderators of this association. Meta-analysis on 85 studies revealed that although basal cortisol levels were generally lower in FSD subjects compared to controls, this association did not reach statistical significance (SMD -0.07, 95% CI -0.17 to 0.04, p=0.241). However, when the three FSD were assessed separately, statistically significant basal hypocortisolism was observed in CFS subjects compared to controls (SMD -0.14, 95% CI -0.28 to 0.00, p=0.047), but not in FM or IBS. When all potential moderators were entered into a meta-regression analysis, only type of FSD and female gender were significant independent predictors of basal hypocortisolism. In conclusion, we did not find evidence to consider all three main FSD as hypocortisolemic disorders, as significant reduction in basal cortisol compared to healthy controls was only found in CFS and in females with FM, but not in IBS.

As good as it gets? A meta-analysis and systematic review of methodological quality of heart rate variability studies in functional somatic disorders.

Autonomic nervous system (ANS) dysfunction is a potential mechanism connecting psychosocial stress to functional somatic disorders (FSD), such as chronic fatigue syndrome, fibromyalgia and irritable bowel syndrome. We present the first meta-analysis and systematic review of methodological study quality on the association between cardiac ANS dysfunction, measured as parasympathetic nervous system (PNS) activity using heart rate variability (HRV), and FSD. Literature search revealed 23 available studies including data on 533 FSD patients. Meta-analysis on a subgroup of 14 studies with suitable outcome measures indicated lower PNS activity in FSD patients compared to controls (weighted standardized mean difference (SMD)=-0.32, 95% CI -0.63 to -0.01, p=0.04). The reliability of this summary estimate was, however, significantly limited by unexplained heterogeneity in the effect sizes and potential publication bias (weighted SMD after correction for funnel plot asymmetry=0.01, 95% CI -0.34 to 0.36, p=0.95). The systematic review of overall methodological quality of HRV studies in FSD demonstrates that there is substantial room for improvement, especially in selection of healthy control subjects, blinding of researchers performing HRV measurements, report of adequate HRV outcomes, and assessment of and adjustment for potential confounders. Methodological study quality was, however, not a significant predictor of study findings. We conclude that current available evidence is not adequate to firmly reject or accept a role of ANS dysfunction in FSD. Quality criteria and recommendations to improve future research on HRV in FSD are provided.