Fluorine-18 and Radiometal Labeling of Biomolecules via Disulfide Rebridging

Biomolecules labeled with positron-emitting radionuclides like fluorine-18 or radiometals like copper-64 and zirconium-89 are increasingly employed in nuclear medicine for diagnosis purposes. Given the fragility and complexity of these compounds, their labeling requires mild conditions. Besides, it is essential to develop methods inducing minimal modification of the tertiary structure, as it is fundamental for the biological activity of such complex entities. Given these requirements, disulfide rebridging represents a promising possibility since it allows protein modification as well as conservation of the tertiary structure. In this context, we have developed an original radiofluorinated dibromopyridazine dione prosthetic group for labeling of disulfide-containing biomolecules via rebridging. We employed it to radiolabel octreotide, a somatostatin analogue, and to radiolabel fragment antigen binding (Fab) targeting programmed death-ligand 1 (PD-L1), whose properties were then evaluated in vitro and in vivo by positron emission tomography (PET) imaging. We next extended our strategy to the radiolabeling of cetuximab, a monoclonal antibody, with various radiometals commonly used in PET imaging (zirconium-89, copper-64) by developing various rebridging molecules bearing the appropriate chelators. The stabilities of the radiolabeled antibody conjugates were assessed in biological conditions.

Efficient PD-L1 imaging of murine glioblastoma with FUS-aided immunoPET by leveraging FcRn-antibody interaction

Rationale: The passage of antibodies through the blood-brain barrier (BBB) and the blood-tumoral barrier (BTB) is determinant not only to increase the immune checkpoint inhibitors efficacy but also to monitor prognostic and predictive biomarkers such as the programmed death ligand 1 (PD-L1) via immunoPET. Although the involvement of neonatal Fc receptor (FcRn) in antibody distribution has been demonstrated, its function at the BBB remains controversial, while it is unknown at the BTB. In this context, we assessed FcRn's role by pharmacokinetic immunoPET imaging combined with focused ultrasounds (FUS) using unmodified and FcRn low-affinity IgGs targeting PD-L1 in a preclinical orthotopic glioblastoma model. Methods: Transcranial FUS were applied over the whole brain in mice shortly before injecting the anti-PD-L1 IgG 89Zr-DFO-C4 or its FcRn low-affinity mutant 89Zr-DFO-C4Fc-MUT in a syngeneic glioblastoma murine model (GL261-GFP). Brain uptake was measured from PET scans acquired up to 7 days post-injection. Kinetic modeling was performed to compare the brain kinetics of both C4 formats. Results: FUS efficiently enhanced the delivery of both C4 radioligands in the brain with high reproducibility. 89Zr-DFO-C4Fc-MUT mean concentrations in the brain reached a significant uptake of 3.75±0.41%ID/cc with FUS against 1.92±0.45%ID/cc without, at 1h post-injection. A substantial and similar entry of both C4 radioligands was observed at a rate of 0.163±0.071 mL/h/g of tissue during 10.4±4.6min. The impaired interaction with FcRn of 89Zr-DFO-C4Fc-MUT significantly decreased the efflux constant from the healthy brain tissue to plasma compared with non-mutated IgG. Abolishing FcRn interaction allows determining the target engagement related to the specific binding as soon as 12h post-injection. Conclusion: Abolishing Fc-FcRn interaction confers improved kinetic properties to 89Zr-DFO-C4Fc-MUT for immunoPET imaging. FUS-aided BBB/BTB disruption enables quantitative imaging of PD-L1 expression by glioblastoma tumors within the brain.

Combining deep mutational scanning to heatmap of HLA class II binding of immunogenic sequences to preserve functionality and mitigate predicted immunogenicity

Removal of CD4 T cell epitopes from therapeutic antibody sequences is expected to mitigate their potential immunogenicity, but its application is complicated by the location of their T cell epitopes, which mainly overlap with complementarity-determining regions. We therefore evaluated the flexibility of antibody sequences to reduce the predicted affinity of corresponding peptides for HLA II molecules and to maintain antibody binding to its target in order to guide antibody engineering for mitigation of predicted immunogenicity. Permissive substitutions to reduce affinity of peptides for HLA II molecules were identified by establishing a heatmap of HLA class II binding using T-cell epitope prediction tools, while permissive substitutions preserving binding to the target were identified by means of deep mutational scanning and yeast surface display. Combinatorial libraries were then designed to identify active clones. Applied to adalimumab, an anti-TNFα human antibody, this approach identified 200 mutants with a lower HLA binding score than adalimumab. Three mutants were produced as full-length antibodies and showed a higher affinity for TNFα and neutralization ability than adalimumab. This study also sheds light on the permissiveness of antibody sequences with regard to functionality and predicted T cell epitope content.

Deciphering cross-species reactivity of LAMP-1 antibodies using deep mutational epitope mapping and AlphaFold

Delineating the precise regions on an antigen that are targeted by antibodies has become a key step for the development of antibody therapeutics. X-ray crystallography and cryogenic electron microscopy are considered the gold standard for providing precise information about these binding sites at atomic resolution. However, they are labor-intensive and a successful outcome is not guaranteed. We used deep mutational scanning (DMS) of the human LAMP-1 antigen displayed on yeast surface and leveraged next-generation sequencing to observe the effect of individual mutants on the binding of two LAMP-1 antibodies and to determine their functional epitopes on LAMP-1. Fine-tuned epitope mapping by DMS approaches is augmented by knowledge of experimental antigen structure. As human LAMP-1 structure has not yet been solved, we used the AlphaFold predicted structure of the full-length protein to combine with DMS data and ultimately finely map antibody epitopes. The accuracy of this method was confirmed by comparing the results to the co-crystal structure of one of the two antibodies with a LAMP-1 luminal domain. Finally, we used AlphaFold models of non-human LAMP-1 to understand the lack of mAb cross-reactivity. While both epitopes in the murine form exhibit multiple mutations in comparison to human LAMP-1, only one and two mutations in the Macaca form suffice to hinder the recognition by mAb B and A, respectively. Altogether, this study promotes a new application of AlphaFold to speed up precision mapping of antibody-antigen interactions and consequently accelerate antibody engineering for optimization.

Impact of Radiolabeling Strategies on the Pharmacokinetics and Distribution of an Anti-PD-L1 PET Ligand

Molecular imaging with PET offers an alternative method to quantify programmed-death-ligand 1 (PD-L1) to accurately select patients for immunotherapies. More and more clinical and preclinical trials involve radiolabeling of antibody fragments for their desirably fast clearance and high tumor penetration. As the radiolabeling strategy can significantly impact pharmacokinetics and biodistribution, we explored in this work a site-specific radiofluorination strategy on an anti-PD-L1 fragment antigen-binding (Fab) and compared the pharmacokinetic and biodistribution properties with the same Fab labeled using stochastic radiolabeling chemistry. We applied an enzymatic bioconjugation mediated by a variant of the lipoic acid ligase (LplA) that promotes the formation of an amide bond between a short peptide cloned onto the C terminus of the Fab. A synthetic analogue of the enzyme natural substrate, lipoic acid, was radiolabeled with fluorine-18 for site-specific conjugation by LplA. We compared the biodistribution of the site-specifically labeled Fab with a stochastically labeled Fab on lysine side chains in tumor-bearing mice. The two methods of fluorination demonstrate a comparable whole-body biodistribution. The ⁸⁹Zr-labeled Fab had different biodistribution compared to either ¹⁸F-labeled Fab. We attribute the difference to [⁸⁹Zr] metabolism. Fab-LAP-[¹⁸F]FPyOctA therefore reflects better the true pharmacokinetic profile of the Fab.

Optimizing Immuno-PET Imaging of Tumor PD-L1 Expression: Pharmacokinetic, Biodistribution, and Dosimetric Comparisons of 89Zr-Labeled Anti-PD-L1 Antibody Formats

PET imaging of programmed cell death ligand 1 (PD-L1) may help to noninvasively predict and monitor responses to anti-programmed cell death 1/anti-PD-L1 immunotherapies. In this study, we compared the imaging characteristics of 3 radioligands derived from the anti-PD-L1 IgG1 complement 4 (C4). In addition to the IgG C4, we produced a fragment antigen-binding (Fab) C4, as well as a double-mutant IgG C4 (H310A/H435Q) with minimal affinity for the murine neonatal Fc receptor. Methods: The pharmacokinetics, biodistribution, and dosimetry of the 3 ⁸⁹Zr-labeled C4 ligands were compared by longitudinal PET/CT imaging in nude mice bearing subcutaneous human non-small cell lung cancer xenografts with positive (H1975 model) or negative (A549 model) endogenous PD-L1 expression. Results: The C4 radioligands substantially accumulated in PD-L1-positive tumors but not in PD-L1-negative tumors or in blocked PD-L1-positive tumors, confirming their PD-L1-specific tumor targeting. ⁸⁹Zr-Fab C4 and ⁸⁹Zr-IgG C4 (H310A/H435Q) were rapidly eliminated compared with ⁸⁹Zr-IgG C4. Consequently, maximal tumor-to-muscle ratios were obtained earlier, at 4 h after injection for ⁸⁹Zr-Fab C4 (ratio, ∼6) and 24 h after injection for ⁸⁹Zr-IgG C4 (H310A/H435Q) (ratio, ∼9), versus 48 h after injection for ⁸⁹Zr-IgG C4 (ratio, ∼8). Background activity in nontumor tissues was low, except for high kidney retention of ⁸⁹Zr-Fab C4 and persistent liver accumulation of ⁸⁹Zr-IgG C4 (H310A/H435Q) compared with ⁸⁹Zr-IgG C4. Dosimetry estimates suggested that the C4 radioligands would yield organ-absorbed doses tolerable for repeated clinical PET imaging studies. Conclusion: This study highlights the potential of designing radioligands with shorter pharmacokinetics for PD-L1 immuno-PET imaging in a preclinical model and encourages further clinical translation of such radioligands.

Monitoring In Vivo Performances of Protein-Drug Conjugates Using Site-Selective Dual Radiolabeling and Ex Vivo Digital Imaging

In preclinical models, the development and optimization of protein-drug conjugates require accurate determination of the plasma and tissue profiles of both the protein and its conjugated drug. To this aim, we developed a bioanalytical strategy based on dual radiolabeling and ex vivo digital imaging. By combining enzymatic and chemical reactions, we obtained homogeneous dual-labeled anti-MMP-14 Fabs (antigen-binding fragments) conjugated to monomethyl auristatin E where the protein scaffold was labeled with carbon-14 (14C) and the conjugated drug with tritium (3H). These antibody-drug conjugates with either a noncleavable or a cleavable linker were then evaluated in vivo. By combining liquid scintillation counting and ex vivo dual-isotope radio-imaging, it was possible not only to monitor both components simultaneously during their circulation phase but also to quantify accurately their amount accumulated within the different organs.

A213 ERCP-RELATED ADVERSE EVENTS IN PRIMARY SCLEROSING CHOLANGITIS: A SYSTEMATIC REVIEW & META-ANALYSIS

Background

Endoscopic retrograde cholangiopancreatography (ERCP) is a valuable diagnostic and therapeutic tool in primary sclerosing cholangitis (PSC). Although the complications of ERCP are well known in the general population, there is conflicting data regarding complications in patients with PSC. Factors that predict ERCP-related adverse events in PSC are also unclear.

Aims

To conduct a systematic review and meta-analyses to 1. compare ERCP-related adverse events in patients with and without PSC and 2. determine risk factors associated with ERCP-related adverse events in PSC.

Methods

A systematic search was conducted in Embase, PubMed and CENTRAL for studies published from January 1, 2000 to May 12, 2021. Eligible studies included adults with PSC undergoing ERCP and reported at least one ERCP-related adverse event (bleeding, perforation, pancreatitis, cholangitis) or risk factor associated with complications. Raw event rates for adverse events and risk factors were used to calculate odds ratios (ORs) which were then pooled using random-effects models.

Results

Four studies contributed to the first meta-analysis. There was a significant three-fold increase in the 30-day odds of cholangitis in PSC compared to those without PSC (4.3% vs. 2.0%; OR 3.26, 95% CI 1.08–9.90; p=0.037; I2=73.0%) (Figure 1). However, there were no significant differences in 30-day pancreatitis (4.2% vs. 3.4%; OR 0.89, 95% CI 0.26–3.07; p=0.851; I2=87.9%), bleeding (0.3% vs. 1.1%; OR 0.36, 95% CI 0.06–2.21; p=0.272; I2=50.3%), or perforation (0.7% vs. 0.5%; OR 1.19, 95% CI 0.40–3.51; p=0.752; I2=28.5%).

In a second meta-analysis, risk factors contributing to post-ERCP pancreatitis (PEP) in PSC were pooled from five studies. While female sex was not associated with PEP, accidental passage of wire into the pancreatic duct (OR 7.44, 95% CI 3.33–16.65; p<0.001; I2=65.0%) and biliary sphincterotomy (OR 4.80, 95% CI 1.92–12.03; p=0.001; I2=73.1%) were associated with higher PEP odds.

Conclusions

In the context of limited comparative data and study heterogeneity, PSC patients have higher odds of post-ERCP cholangitis despite the majority receiving antibiotics. Odds of bleeding, pancreatitis, and perforation were similar between groups. Accidental wire passage and biliary sphincterotomy increased odds of PEP, which helps identify higher-risk groups. Future studies should elucidate ERCP-related risks in PSC and guide preventive strategies.

Funding Agencies

None

Deep mutational engineering of broadly-neutralizing nanobodies accommodating SARS-CoV-1 and 2 antigenic drift

Here, we report the molecular engineering of nanobodies that bind with picomolar affinity to both SARS-CoV-1 and SARS-CoV-2 receptor-binding domains (RBD) and are highly neutralizing. We applied deep mutational engineering to VHH72, a nanobody initially specific for SARS-CoV-1 RBD with little cross-reactivity to SARS-CoV-2 antigen. We first identified all the individual VHH substitutions that increase binding to SARS-CoV-2 RBD and then screened highly focused combinatorial libraries to isolate engineered nanobodies with improved properties. The corresponding VHH-Fc molecules show high affinities for SARS-CoV-2 antigens from various emerging variants and SARS-CoV-1, block the interaction between ACE2 and RBD, and neutralize the virus with high efficiency. Its rare specificity across sarbecovirus relies on its peculiar epitope outside the immunodominant regions. The engineered nanobodies share a common motif of three amino acids, which contribute to the broad specificity of recognition. Our results show that deep mutational engineering is a very powerful method, especially to rapidly adapt existing antibodies to new variants of pathogens.

Ustekinumab in bio-naïve and bio-failure Crohn's disease patients: Results from a « real-life » monocentric cohort

BACKGROUND

The pivotal clinical trials have largely demonstrated the efficacy and safety of ustekinumab in Crohn's disease. Real-life cohorts published so far only include very few bio-naïve patients. This study assesses effectiveness and safety of ustekinumab in bio-naïve and bio-failure patients treated with ustekinumab in routine practice and look for predictors of response.

METHODS

We performed a retrospective monocentric study. Initial response was assessed by maintenance therapy beyond week 16. Sustained response was assessed by the continuation or cessation of therapy over time for another reason than stopping in sustained remission. Treatment persistence was assessed by Kaplan Meier curves and predictors of treatment persistence were studied by univariate and multivariate Cox model.

RESULTS

Out of 156 recorded patients, three patients were still in their induction phase at time of analysis and 5 patients were lost to follow-up, leaving 148 patients for clinical effectiveness analyses, including 35 bio-naïve when starting ustekinumab. A maintenance therapy was initiated in 79.7%. At one year, the probability to be still treated with ustekinumab was 73.8%. Treatment cessation increased with smoking in multivariate analysis. Previous biologic failure (as a whole), CRP and fecal calprotectin baseline levels did not influence initial response and treatment persistence.

CONCLUSION

A large proportion of CD patients initially respond to ustekinumab and continue this treatment beyond one year. Treatment persistence is as high in bio-failure as in bio-naïve patients.

Abstract A55: Circulating tumor DNA in newly diagnosed intermediate-risk rhabdomyosarcoma

Background: Patients with intermediate-risk rhabdomyosarcoma (IR RMS) have approximately 60-70% chance of survival with current therapies. However, biomarkers of outcome and response to therapy are lacking for these patients. Circulating tumor DNA (ctDNA) has been shown to be prognostic in a wide range of cancer types, but it is unknown whether patients with IR RMS have detectable levels of ctDNA.

Objective: To study ctDNA prevalence and prognostic impact in newly diagnosed IR RMS, we utilized two next-generation sequencing (NGS) approaches that detect the presence of somatic copy-number changes and oncogenic translocations.

Methods: Cell-free DNA was extracted from serum samples obtained from patients with newly diagnosed IR RMS who enrolled on the COG studies ARST0531 and D9803, including patients with embryonal (ERMS) and alveolar (ARMS) histology subtypes. While both subtypes are characterized by frequent somatic copy-number variants (CNVs), ARMS is also defined by recurrent translocations. To detect CNVs, we performed ultra-low passage whole-genome sequencing (ULP-WGS). Translocations were detected with a validated custom hybrid capture assay (TranSS-Seq).

Results: Serum samples were analyzed from 132 patients with IR RMS, including 75 with ERMS and 57 with ARMS. ctDNA was detected by CNVs in 70% (92/132) of IR RMS patients with similar detection rates in each histology: 65% (49/75) in ERMS and 75% (43/57) in ARMS. Among the ARMS samples sequenced, only 37% (18/49) were positive by TranSS-Seq. Furthermore, copy-number events resulting in amplifications of the somatic translocation frequently resulted in miscalculation of ctDNA content by the TranSS-Seq method. Estimates of event-free and overall survival were lower in patients with detectable ctDNA, though the differences were not statistically significant.

Conclusion: Patients with IR RMS frequently have detectable levels of ctDNA that can be measured by NGS assays designed to detect somatic structural events. This study relied on previously banked serum samples and a relatively small retrospective analysis. These findings provide justification for our current efforts to utilize a large prospective study, COG ARST1431, to collect pretreatment and serial blood samples using procedures optimized for ctDNA assays. Sequencing of matched tumor samples is ongoing to understand the differences in sensitivity between ULP-WGS and TranSS-Seq for ctDNA detection in patients with ARMS.

Citation Format: Samuel Abbou, David Hall, Donald A. Barkauskas, Kelly Klega, Anwesha Nag, Aaron R. Thorner, Mark Krailo, Steven Dubois, Douglas S. Hawkins, Brian D. Crompton. Circulating tumor DNA in newly diagnosed intermediate-risk rhabdomyosarcoma [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr A55.

Abstract 3365: Pediatric trials and labeling information for newly approved cancer therapies with targets potentially relevant to pediatric cancers

Objective: Few new therapies have been approved for pediatric cancers. In 2017, Congress enacted the Research to Accelerate Cures and Equity (RACE) for Children Act, which requires pediatric studies for adult cancer drugs with a molecular target relevant to a pediatric cancer. The pediatric study requirements will apply to new drugs approved by the FDA beginning in 2020. To inform the implementation of this new law, we evaluated pediatric trials and labeling information available for cancer drugs approved by the FDA.

Methods: We identified new adult cancer drugs approved by the FDA from January 2007 to December 2017 using the Drugs@FDA database. New formulations, drugs approved only for pediatric cancers, and imaging and contrast agents were excluded. For each drug, the potential pediatric relevance of the molecular target was determined using the Pediatric Molecular Target List published by the FDA in August 2018. Information on pediatric clinical trials, enrollment, and start and end dates was obtained from ClinicalTrials.gov as of September 2018. Drug labels were examined for pediatric efficacy, safety, or PK/PD and dosing data. A trial potentially open to children was defined as a study for which any participants < 18 years of age were eligible. We also examined pediatric studies, defined as trials for which the midpoint of the eligible age range was < 21 years.

Results: Among the 78 adult cancer drugs approved between 2007 and 2017, 61 (78%) had targets considered potentially relevant for pediatrics under the RACE Act. At the time of approval, 4 (5%) drugs had any pediatric labeling information. As of September 2018, after a median follow-up of 5.1 years (IQR: 2.9-7.0 y) from the date of first FDA approval, 17 (22%) had any pediatric information, and 8 (10%) had a pediatric indication. For these 17 drugs, the median time from first approval to addition of any pediatric information was 1.5 years (IQR: 1.1-4.6 y). Overall, 362 trials identified on ClinicalTrials.gov (total planned enrollment: 57,827 participants) were potentially open to children for 67 of the 78 drugs (86%), including 57 drugs (93%) with targets on the Pediatric Molecular Target List. For these 67 drugs, the earliest planned end date for trials open to children was a median of 3.3 years after first approval (IQR: 0.2-5.5 y). There were 171 solely pediatric studies for 56 (72%) drugs, and the earliest planned trial end was a median of 4.2 years (IQR: 2.3-5.9 y) after first approval.

Conclusions: Less than a quarter of FDA-approved cancer drugs include information on use in children, and most clinical trials open to children are not expected to be completed until several years after FDA approval. Under the RACE Act, most new drugs for adult cancers are likely to be subject to pediatric study requirements, indicating that timely completion of such trials may substantially increase the pediatric data available for cancer therapies.

Citation Format: Thomas J. Hwang, Liat Orenstein, Steven Dubois, Florence Bourgeois. Pediatric trials and labeling information for newly approved cancer therapies with targets potentially relevant to pediatric cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3365.

Reprogramming Escherichia coli for the production of prenylated indole diketopiperazine alkaloids

Prenylated indole diketopiperazine (DKP) alkaloids are important bioactive molecules or their precursors. In the context of synthetic biology, efficient means for their biological production would increase their chemical diversification and the discovery of novel bioactive compounds. Here, we prove the suitability of the Escherichia coli chassis for the production of prenylated indole DKP alkaloids. We used enzyme combinations not found in nature by co-expressing bacterial cyclodipeptide synthases (CDPSs) that assemble the DKP ring and fungal prenyltransferases (PTs) that transfer the allylic moiety from the dimethylallyl diphosphate (DMAPP) to the indole ring of tryptophanyl-containing cyclodipeptides. Of the 11 tested combinations, seven resulted in the production of eight different prenylated indole DKP alkaloids as determined by LC-MS/MS and NMR characterization. Two were previously undescribed. Engineering E. coli by introducing a hybrid mevalonate pathway for increasing intracellular DMAPP levels improved prenylated indole DKP alkaloid production. Purified product yields of 2–26 mg/L per culture were obtained from culture supernatants. Our study paves the way for the bioproduction of novel prenylated indole DKP alkaloids in a tractable chassis that can exploit the cyclodipeptide diversity achievable with CDPSs and the numerous described PT activities.

[Pharmaceutical analysis of medication orders in health care facilities: A France-Quebec comparison]

OBJECTIVES

The pharmaceutical analysis of drug prescriptions is one of the key steps in the drug circuit. This mandatory regulatory practice in France and Quebec is based on national standards. The main objective of this work was to compare the practical methods of pharmaceutical analysis performed in French and Quebec university hospitals.

METHODS

This is a prospective comparative survey conducted in 2 French and Quebec university hospital centres among pharmacists and pharmacy residents.

RESULTS

The response rate to the survey was 60% (45/75). Between 16 and 22 elements were deemed necessary to structure the centralized, decentralized or mixed pharmaceutical analysis. The chronological ranking of these elements was comparable between the French and Quebec participants. All participants were in favour of the development of initial and continuing training in pharmaceutical analysis. Finally, the majority of participants were against using individual pharmaceutical analysis performance indicators to optimize the process (82%; 37/45).

CONCLUSIONS

The French-Quebec practice of prescription analysis by a ward-pharmacist complies with national standards. The main differences in the practice of pharmaceutical analysis are related to the types of organization, the tools available and the length of time pharmacists have been deployed in care units in France and Quebec.

Abstract PR05: Genomic analysis of osteosarcoma reveals opportunities for targeted therapy

Osteosarcoma (OS) patients who relapse after initial therapy or present with metastatic disease have an extremely poor prognosis. Chemotherapy regimens for these patients have limited efficacy and significant toxicities. Thus, new therapeutic approaches are urgently needed. OS is characterized by numerous copy-number alterations (CNAs) and structural variations (SVs) in cancer-relevant genes. In contrast, recurrent point mutations are not seen. Thus, OS is a C-class (copy number-driven) rather than an M-class (mutation-driven) cancer. However, little is known with regards to whether copy-number alterations can be used to select therapies for aggressive cancers such as OS. The genomic heterogeneity of OS suggests that there may be different oncogenic drivers in subsets of patients. Thus, a systematic effort to identify targetable, patient-specific key driver genes (likely CNAs) is required.

We established a clinically annotated patient-derived tumor xenograft (PDTX) bank of 16 OS samples obtained at diagnosis, after surgical resection, and from metastasis, thus representing the full spectrum of disease. Comparison between PDTXs with a corresponding matched primary tumor demonstrated high correlation in copy number (by WGS for 12 samples) and gene expression (by RNAseq for 13 samples), suggesting that PDTXs are faithful preclinical models for OS. To identify recurrent CNAs, we analyzed this WGS dataset together with a public dataset of OS WGS samples. With this combined dataset of 69 samples from 52 patients, we searched for recurrent CNAs across an actionable cancer gene list and identified genes amplified at least 4-fold in at least 2 samples. The two most frequently amplified genes in OS are CCNE1 and MYC. Other frequent alterations were those in the PI3K pathway (PTEN loss and/or AKT amplification), AURKB amplification, CDK4 amplification, and VEGFA amplification. Importantly, all of these CNAs were reflected in at least one PDTX model. We hypothesized that in OS some of these CNAs are key cancer drivers that can be targeted for cancer treatment. To test this hypothesis, we rank-ordered the CNAs in 9 PDTXs by the amplitude of the copy number gain. We used this simple heuristic to identify candidate drivers for individual samples. We then identified 6 drugs that could be used to target specific amplified genes and tested these drugs in corresponding CNA-matched PDTX. In all cases, we saw significant growth inhibition in matched PDTXs whereas the effect was minimal in PDTXs treated with unmatched therapies. These results support the hypothesis that specific genes within CNA serve as oncogenic drivers in OS and thus outline a feasible approach to personalized, genome-informed therapy for this disease. This work could serve as the necessary preclinical proof of principle for development of a targeted therapy basket trial for OS.

In parallel to these studies and in order to further define the evolutionary trajectory of OS, we have carried out a comprehensive analysis of both spatial and temporal changes that occur in OS samples from the same patient. This has allowed us to begin defining the role of whole-genome duplication events and chromothripsis as well as loss of heterozygosity in the evolution of OS. We are directing our current efforts towards merging this evolutionary analysis with knowledge of possible targetable events to further identify key vulnerabilities that could be exploited for therapeutic benefit.

Citation Format: Leanne Sayles, Marcus Breese, Amanda Koehne, Krystal Straessler, Stanley Leung, Aviv Spillinger, Doug Hawkins, Steven Dubois, Alex Lee, Bogdan Tanasa, Kim Miok, Avanthi Shah, Sheri Spunt, Neyssa Marina, Kim Hazard, Alejandro Sweet-Cordero. Genomic analysis of osteosarcoma reveals opportunities for targeted therapy [abstract]. In: Proceedings of the AACR Special Conference: Pediatric Cancer Research: From Basic Science to the Clinic; 2017 Dec 3-6; Atlanta, Georgia. Philadelphia (PA): AACR; Cancer Res 2018;78(19 Suppl):Abstract nr PR05.

Transition from pediatric to adult care in adolescents with hereditary metabolic diseases: Specific guidelines from the French network for rare inherited metabolic diseases (G2M)

Inherited metabolic diseases (IMD) form a heterogeneous group of genetic disorders that surface primarily during childhood and result in significant morbidity and mortality. A prevalence of 1 in 2500-5000 live births is often reported. The transfer of adolescents from pediatric care to adult health facilities is often difficult for patients and their families and can lead to a breakdown in medical follow-up and therefore serious complications. Existing recommendations for the successful transition of patients with chronic disorders do not specifically address patients with IMDs associated with dietary treatment. Here, the French network for rare inherited metabolic diseases (G2M) presents its reflections and recommendations for a successful transition. Preparations for the transfer must be made well in advance. The transfer must aim for adolescents gaining autonomy by making them responsible and providing them with the knowledge that will enable them to manage their care themselves, know how to react appropriately if there is any change in their condition, and move comfortably within the adult healthcare system. This requires the active participation of the patient, his or her family, and pediatric and adult care teams. It involves multidisciplinary management plus the production and maintenance of an educational therapy program. Finally, the identification of physicians and dietitians trained in IMDs, relevant subspecialists, and even expert patients could improve the continuum of complete and appropriate care for these patients within adult medicine.

Dietary practices in propionic acidemia: A European survey

Background

The definitive dietary management of propionic acidaemia (PA) is unknown although natural protein restriction with adequate energy provision is of key importance.

Aim

To describe European dietary practices in the management of patients with PA prior to the publication of the European PA guidelines.

Methods

This was a cross-sectional survey consisting of 27 questions about the dietary practices in PA patients circulated to European IMD dietitians and health professionals in 2014.

Results

Information on protein restricted diets of 186 PA patients from 47 centres, representing 14 European countries was collected. Total protein intake [PA precursor-free L-amino acid supplements (PFAA) and natural protein] met WHO/FAO/UNU (2007) safe protein requirements for age in 36 centres (77%). PFAA were used to supplement natural protein intake in 81% (n = 38) of centres, providing a median of 44% (14–83%) of total protein requirement. Seventy-four per cent of patients were prescribed natural protein intakes below WHO/FAO/UNU (2007) safe levels in one or more of the following age groups: 0–6 m, 7–12 m, 1–10 y, 11–16 y and > 16 y. Sixty-three per cent (n = 117) of patients were tube fed (74% gastrostomy), but only 22% received nocturnal feeds.

Conclusions

There was high use of PFAA with intakes of natural protein commonly below WHO/FAO/UNU (2007) safe levels. Optimal dietary management can only be determined by longitudinal, multi-centre, prospective case controlled studies. The metabolic instability of PA and small patient cohorts in each centre ensure that this is a challenging undertaking.

Neurovascular microcirculatory vasodilation mediated by C-fibers and Transient receptor potential vanilloid-type-1 channels (TRPV 1) is impaired in type 1 diabetes

Microvascular dysfunction may have an early onset in type 1 diabetes (T1D) and can precede major complications. Our objectives were to assess the endothelial-dependent (acetylcholine, ACh; and post-occlusive hyperemia, PORH), non-endothelial-dependent (sodium nitroprusside, SNP) and neurovascular-dependent (local heating, LH and current induced vasodilation, CIV) microcirculatory vasodilation in T1D patients compared with matched control subjects using a laser speckle contrast imager. Seventeen T1D patients - matched with 17 subjects according to age, gender, Body-Mass-Index, and smoking status - underwent macro- and microvascular investigations. The LH early peak assessed the transient receptor potential vanilloid type 1 channels (TRPV1) mediated vasodilation, whereas the plateau assessed the Nitirc-Oxyde (NO) and endothelium-derived hyperpolarizing factor (EDHF) pathways. PORH explored sensory nerves and (EDHF), while CIV assessed sensory nerves (C-fibers) and prostaglandin-mediated vasodilation. Using neurological investigations, we observed that C-fiber and A-delta fiber functions in T1D patients were similar to control subjects. PORH, CIV, LH peak and plateau vasodilations were significantly decreased in T1D patients compared to controls, whereas there was no difference between the two groups for ACh and SNP vasodilations. Neurovascular microcirculatory vasodilations (C-fibers and TRPV 1-mediated vasodilations) are impaired in TD1 patients whereas no abnormalities were found using clinical neurological investigations. Clinicaltrials: No. NCT02538120.

Dietary practices in isovaleric acidemia: A European survey

Background

In Europe, dietary management of isovaleric acidemia (IVA) may vary widely. There is limited collective information about dietetic management.

Aim

To describe European practice regarding the dietary management of IVA, prior to the availability of the E-IMD IVA guidelines (E-IMD 2014).

Methods

A cross-sectional questionnaire was sent to all European dietitians who were either members of the Society for the Study of Inborn Errors of Metabolism Dietitians Group (SSIEM-DG) or whom had responded to previous questionnaires on dietetic practice (n = 53). The questionnaire comprised 27 questions about the dietary management of IVA.

Results

Information on 140 patients with IVA from 39 centres was reported. 133 patients (38 centres) were given a protein restricted diet. Leucine-free amino acid supplements (LFAA) were routinely used to supplement protein intake in 58% of centres. The median total protein intake prescribed achieved the WHO/FAO/UNU [2007] safe levels of protein intake in all age groups. Centres that prescribed LFAA had lower natural protein intakes in most age groups except 1 to 10 y. In contrast, when centres were not using LFAA, the median natural protein intake met WHO/FAO/UNU [2007] safe levels of protein intake in all age groups. Enteral tube feeding was rarely prescribed.

Conclusions

This survey demonstrates wide differences in dietary practice in the management of IVA across European centres. It provides unique dietary data collectively representing European practices in IVA which can be used as a foundation to compare dietary management changes as a consequence of the first E-IMD IVA guidelines availability.

[Selection and optimal sequence of critical elements for medication review: A simulation with hospital pharmacy residents]

OBJECTIVES

The main objective of this study was to compare the responses of pharmacy residents regarding critical steps for medication order review, in the presence or absence of clinical pharmacists on patient care units, to describe the sequence of these steps and to compare them to an optimal sequence. The secondary objectives were to test this sequence in a simulation and to assess the residents' level of agreement on medication order review.

METHODS

Twenty-two validation steps were selected from guidelines. A simulation on order review was organized in three steps: selecting elements judged to be necessary or not for the order review critical path, then organizing this sequence in chronological order, implementation of this critical path on two simulated practical cases, resident perceptions about order review in their training.

RESULTS

Forty-one residents participated in the activity. Responses were heterogeneous regarding the elements' sequence and the time required for the review of a simulated case (3-13minutes). A majority of residents considered that their training was insufficient (29/41), that pharmacists validated differently (27/41), and that it was impossible to review the 22 proposed items for each prescription (30/41).

CONCLUSIONS

This article highlights heterogeneous medication order review practices among pharmacy residents, due to a lack of training in their curriculum according to them. It is essential to acquire medication order review standard both locally and nationally.

Osteoprotegerin levels are associated with liver fat and liver markers in dysmetabolic adults

AIM

This study aimed to determine the association between visceral adipose tissue (VAT), liver fat (LF) content, and other markers of the metabolic syndrome (MetS) and osteoprotegerin (OPG) in dysmetabolic adults.

METHODS

Subjects from the NUMEVOX cohort were included if they fulfilled at least one MetS criterion. They then underwent a thorough metabolic and cardiovascular evaluation, including arterial stiffness, atherosclerotic plaques, homoeostasis model assessment for insulin resistance (HOMA-IR) indices and OPG. VAT and LF content were measured by magnetic resonance imaging (MRI). Ultrasound examination of arteries and arterial stiffness were recorded, and age- and gender-adjusted paired correlations calculated.

RESULTS

Body mass index, waist circumference and MRI-derived VAT correlated with OPG, whereas abdominal subcutaneous fat did not. OPG levels were strongly correlated with LF content (r=0.25, P=0.003), liver markers such as alanine aminotransferase (r=0.39, P<0.001) and HOMA-IR index (r=0.39, P<0.0001). Plasma OPG also correlated with arterial stiffness and the number of atherosclerotic sites.

CONCLUSION

Plasma OPG levels are positively associated with both liver markers and increased LF content, but not with subcutaneous fat in dysmetabolic men. These findings suggest that elevated OPG levels may play a role in the link between fatty liver disease and enhanced cardiovascular risk.

2 × 2 Tables: a note on Campbell's recommendation

For 2 × 2 tables, Egon Pearson's N - 1 chi-squared statistic is theoretically more sound than Karl Pearson's chi-squared statistic, and provides more accurate p values. Moreover, Egon Pearson's N - 1 chi-squared statistic is equal to the Mantel-Haenszel chi-squared statistic for a single 2 × 2 table, and as such, is often available in statistical software packages like SPSS, SAS, Stata, or R, which facilitates compliance with Ian Campbell's recommendations.

Infection control in households of drug-resistant tuberculosis patients co-infected with HIV in Mumbai, India

BACKGROUND

Mumbai has a population of 21 million, and an increasingly recognised epidemic of drug-resistant tuberculosis (DR-TB).

OBJECTIVE

To describe TB infection control (IC) measures implemented in households of DR-TB patients co-infected with the human immunodeficiency virus (HIV) under a Médecins Sans Frontières programme.

METHODS

IC assessments were carried out in patient households between May 2012 and March 2013. A simplified, standardised assessment tool was utilised to assess the risk of TB transmission and guide interventions. Administrative, environmental and personal protective measures were tailored to patient needs.

RESULTS

IC assessments were carried out in 29 houses. Measures included health education, segregating sleeping areas of patients, improving natural ventilation by opening windows, removing curtains and obstacles to air flow, installing fans and air extractors and providing surgical masks to patients for limited periods. Environmental interventions were carried out in 22 houses.

CONCLUSIONS

TB IC could be a beneficial component of a comprehensive TB and HIV care programme in households and communities. Although particularly challenging in slum settings, IC measures that are feasible, affordable and acceptable can be implemented in such settings using simplified and standardised tools. Appropriate IC interventions at household level may prevent new cases of DR-TB, especially in households of patients with a lower chance of cure.

Practices in prescribing protein substitutes for PKU in Europe: No uniformity of approach

BACKGROUND

There appears little consensus concerning protein requirements in phenylketonuria (PKU).

METHODS

A questionnaire completed by 63 European and Turkish IMD centres from 18 countries collected data on prescribed total protein intake (natural/intact protein and phenylalanine-free protein substitute [PS]) by age, administration frequency and method, monitoring, and type of protein substitute. Data were analysed by European region using descriptive statistics.

RESULTS

The amount of total protein (from PS and natural/intact protein) varied according to the European region. Higher median amounts of total protein were prescribed in infants and children in Northern Europe (n=24 centres) (infants <1 year, >2-3g/kg/day; 1-3 years of age, >2-3 g/kg/day; 4-10 years of age, >1.5-2.5 g/kg/day) and Southern Europe (n=10 centres) (infants <1 year, 2.5 g/kg/day, 1-3 years of age, 2 g/kg/day; 4-10 years of age, 1.5-2 g/kg/day), than by Eastern Europe (n=4 centres) (infants <1 year, 2.5 g/kg/day, 1-3 years of age, >2-2.5 g/kg/day; 4-10 years of age, >1.5-2 g/kg/day) and with Western Europe (n=25 centres) giving the least (infants <1 year, >2-2.5 g/kg/day, 1-3 years of age, 1.5-2 g/kg/day; 4-10 years of age, 1-1.5 g/kg/day). Total protein prescription was similar in patients aged >10 years (1-1.5 g/kg/day) and maternal patients (1-1.5 g/kg/day).

CONCLUSIONS

The amounts of total protein prescribed varied between European countries and appeared to be influenced by geographical region. In PKU, all gave higher than the recommended 2007 WHO/FAO/UNU safe levels of protein intake for the general population.

The influences of psychotic symptoms on the activities of daily living of individuals with Alzheimer disease: a longitudinal analysis

OBJECTIVES

Psychotic symptoms associated with Alzheimer Disease (AD) contribute to excess functional dependence. Longitudinal studies have generally examined the association between rates of functional decline and the occurrence of psychotic symptoms from either a single evaluation or from multiple evaluations rather than through changes in frequency and severity of symptoms. Although the presence or absence of psychotic symptoms at initial or follow-up examinations may be associated with changes in functional status, the nature of the relationship between changes in these domains cannot be inferred. We examine the association between changes in the frequency of psychotic symptoms and changes in dependence in activities of daily living (ADL) over a period ranging from 1 to 74 months (median = 17.7).

METHOD

Data from a cohort of 234 individuals referred to a memory clinic were analyzed using multilevel linear regression. Information on ADL, behavioral and psychological symptoms, depression, and cognition was collected.

RESULTS

An increase in the frequency of psychotic symptoms had a unique influence on the deterioration of basic ADL, after controlling for demographic variables, changes in cognition, depression, and other behavioral and psychological symptoms (B = -.017, p = .003). However, changes in psychotic symptoms did not significantly contribute to declines in the ability to perform instrumental ADL (B = -.008, p = .439).

CONCLUSION

Changes in psychotic symptoms may influence basic but not instrumental ADL over time. These findings may have ramifications for studies and treatment plans for individuals with AD who demonstrate psychotic symptoms.

Dietary management of urea cycle disorders: European practice

BACKGROUND

There is no published data comparing dietary management of urea cycle disorders (UCD) in different countries.

METHODS

Cross-sectional data from 41 European Inherited Metabolic Disorder (IMD) centres (17 UK, 6 France, 5 Germany, 4 Belgium, 4 Portugal, 2 Netherlands, 1 Denmark, 1 Italy, 1 Sweden) was collected by questionnaire describing management of patients with UCD on prescribed protein restricted diets.

RESULTS

Data for 464 patients: N-acetylglutamate synthase (NAGS) deficiency, n=10; carbamoyl phosphate synthetase (CPS1) deficiency, n=29; ornithine transcarbamoylase (OTC) deficiency, n=214; citrullinaemia, n=108; argininosuccinic aciduria (ASA), n=80; arginase deficiency, n=23 was reported. The majority of patients (70%; n=327) were aged 0-16y and 30% (n=137) >16y. Prescribed median protein intake/kg body weight decreased with age with little variation between disorders. The UK tended to give more total protein than other European countries particularly in infancy. Supplements of essential amino acids (EAA) were prescribed for 38% [n=174] of the patients overall, but were given more commonly in arginase deficiency (74%), CPS (48%) and citrullinaemia (46%). Patients in Germany (64%), Portugal (67%) and Sweden (100%) were the most frequent users of EAA. Only 18% [n=84] of patients were prescribed tube feeds, most commonly for CPS (41%); and 21% [n=97] were prescribed oral energy supplements.

CONCLUSIONS

Dietary treatment for UCD varies significantly between different conditions, and between and within European IMD centres. Further studies examining the outcome of treatment compared with the type of dietary therapy and nutritional support received are required.

Treatment of acute decompensation of maple syrup urine disease in adult patients with a new parenteral amino-acid mixture

BACKGROUND

Acute decompensation of maple syrup urine disease (MSUD) is usually treated by enteral feeding with an amino-acid mixture without leucine (Leu), valine or isoleucine. However, its administration is ineffective in cases of gastric intolerance and some adult patients refuse enteral feeding via a nasogastric tube. We developed a new parenteral amino-acid mixture for patients with MSUD.

METHODS

Seventeen decompensation episodes in four adult patients with MSUD treated with a parenteral amino-acid mixture (group P) were compared to 18 previous episodes in the same patients treated by enteral feeding (group E).

RESULTS

The mean Leu concentration at presentation was similar in the groups P and E (1196.9 μmol/L and 1212.2 μmol/L, respectively). The mean decrease in the Leu concentration during the first 3 days of hospitalisation was significantly higher in group P than group E (p = 0.0026); there were no side effects. The mean duration of hospitalisation was similar (4 vs. 4.5 days, p = NS). No patient in group P deteriorated whereas one patient in group E required dialysis.

CONCLUSION

This new parenteral amino-acid mixture is safe and allows efficient Leu concentration decrease during acute MSUD decompensation episodes in adults. Its use avoids the need for nasogastric tube insertion.

The costimulatory molecule CD70 is regulated by distinct molecular mechanisms and is associated with overall survival in diffuse large B-cell lymphoma

In diffuse large B-cell lymphomas (DLBCL), a recurrent deletion of the 19p13 region has recently been described. CD70 and TNFSF9 genes are suspected tumor suppressor genes, but previous studies suggest an oncogenic role for CD70. Therefore, we studied the consequences of variation in CD70 copy number and epigenetic modifications on CD70 expression. Copy-number variation was investigated in 144 de novo DLBCL tissues by comparative genomic hybridization array and quantitative multiplex PCR. Gene expression was assessed by quantitative RT-PCR, and CD70 promoter methylation was determined by pyrosequencing. The 19p13.3.2 region was deleted in 21 (14.6%) cases, which allowed the minimal commonly deleted region of 57 Kb that exclusively includes the CD70 gene to be defined. Homozygous deletions were observed in four (2.7%) cases, and acquired single-nucleotide variations of CD70 were detected in nine (6.3%) cases. CD70 was highly expressed in both germinal centre B-cell-like (GCB) and activated B-cell-like (ABC) DLBCL compared to normal tissue, with distinct molecular mechanisms of mRNA expression regulation. A gene dosage effect was observed in the GCB subtype, whereas promoter methylation was the predominant mechanism of down regulation in the ABC subtype. However, high CD70 expression levels correlated to shorter overall survival in both the GCB (P = 0.0021) and the ABC (P =0.0158) subtypes. In conclusion, CD70 is targeted by recurrent deletions, somatic mutations and promoter hypermethylation, but its high level of expression is related to an unfavorable outcome, indicating that this molecule may constitute a potential therapeutic target in selected DLBCL.

Substrate and reaction specificity of Mycobacterium tuberculosis cytochrome P450 CYP121: insights from biochemical studies and crystal structures

Cytochrome P450 CYP121 is essential for the viability of Mycobacterium tuberculosis. Studies in vitro show that it can use the cyclodipeptide cyclo(l-Tyr-l-Tyr) (cYY) as a substrate. We report an investigation of the substrate and reaction specificities of CYP121 involving analysis of the interaction between CYP121 and 14 cYY analogues with various modifications of the side chains or the diketopiperazine (DKP) ring. Spectral titration experiments show that CYP121 significantly bound only cyclodipeptides with a conserved DKP ring carrying two aryl side chains in l-configuration. CYP121 did not efficiently or selectively transform any of the cYY analogues tested, indicating a high specificity for cYY. The molecular determinants of this specificity were inferred from both crystal structures of CYP121-analog complexes solved at high resolution and solution NMR spectroscopy of the analogues. Bound cYY or its analogues all displayed a similar set of contacts with CYP121 residues Asn(85), Phe(168), and Trp(182). The propensity of the cYY tyrosyl to point toward Arg(386) was dependent on the presence of the DKP ring that limits the conformational freedom of the ligand. The correct positioning of the hydroxyl of this tyrosyl was essential for conversion of cYY. Thus, the specificity of CYP121 results from both a restricted binding specificity and a fine-tuned P450 substrate relationship. These results document the catalytic mechanism of CYP121 and improve our understanding of its function in vivo. This work contributes to progress toward the design of inhibitors of this essential protein of M. tuberculosis that could be used for antituberculosis therapy.

Effect of thermal heat stress on energy utilization in two lines of pigs divergently selected for residual feed intake

Castrated males from 2 lines of purebred French Large White obtained from a divergent selection experiment for their residual feed intake (RFI) over 7 generations were measured for their energy utilization during thermal acclimation to increased ambient temperature. The RFI(+) line consumed more feed than predicted from its performance, whereas the RFI- line consumed less feed. Each pig was exposed to 24°C for 7 d (P0) and thereafter to a constant temperature of 32°C for 3 consecutive periods of 7 d (P1, P2, P3). Feed intake, feeding behavior parameters, digestibility, components of heat production (HP; measured by indirect calorimetry in respiration chambers), and energy, nitrogen, fat, and water balance were measured in pigs offered feed and water ad libitum and individually housed in respiratory chambers. Two identical respiratory chambers were simultaneously used, and 5 pigs of each line were measured successively. Whatever the trait, the interaction between line and period was not significant (P > 0.10). On average, ADFI was greater in the RFI+ than in the RFI- line (1,945 vs. 1,639 g/d; P = 0.051) in relation to an increase of the mean size of each feeding bout (128 vs. 82 g/visit; P < 0.001). There was no line effect on nutrient and energy digestibility. Total HP tended to be greater in RFI+ than in RFI- lines (1,279 vs. 1,137 kJ·kg BW-0.60·d-1; P = 0.065), which tended to retain more energy (968 vs. 798 kJ·kg BW-0.60·d-1; P = 0.050). The sensible heat loss was greater in RFI+ compared with the RFI- line (644 vs. 560 kJ·kg BW-0.60·d-1; P = 0.020). The RFI+ pigs consumed more water (+981 vs. 657 g·kg BW-0.60·d-1; P = 0.085) and produced more urine (589 vs. 292 g·kg BW-0.60·d-1; P < 0.001) than RFI- pigs, whereas water evaporation was similar for both lines. On average, ME intake and HP declined by about 38% and 20%, respectively, from P0 to P1 (P < 0.001). In contrast to ME intake, HP gradually decreased (P < 0.05) from P1 to P3 in connection with a reduction of the activity related HP. The evaporative heat loss represented 30% on the total heat loss on P0, and this proportion significantly increased on P1 (61%; P < 0.001) and remained constant thereafter. In conclusion, our results suggest that thermal heat acclimation in pigs is mainly related to a biphasic reduction of HP rather than a change in the ability of losing heat, and it did not significantly differ between RFI+ and RFI- lines despite a decreased HP in the latter ones.