Complex N-glycosylation of mGluR6 is required for trans-synaptic interaction with ELFN adhesion proteins

Synaptic transmission from retinal photoreceptors to downstream ON-type bipolar cells (BCs) depends on the postsynaptic metabotropic glutamate receptor mGluR6, located at the BC dendritic tips. Glutamate binding to mGluR6 initiates G-protein signaling that ultimately leads to BC depolarization in response to light. The mGluR6 receptor also engages in trans-synaptic interactions with presynaptic ELFN adhesion proteins. The roles of post-translational modifications in mGluR6 trafficking and function are unknown. Treatment with glycosidase enzymes PNGase F and Endo H demonstrated that both endogenous and heterologously expressed mGluR6 contain complex N-glycosylation acquired in the Golgi. Pull-down experiments with ELFN1 and ELFN2 extracellular domains revealed that these proteins interact exclusively with the complex glycosylated form of mGluR6. Mutation of the four predicted N-glycosylation sites, either singly or in combination, revealed that all four sites are glycosylated. Single mutations partially reduced, but did not abolish, surface expression in heterologous cells, while triple mutants had little or no surface expression, indicating that no single glycosylation site is necessary or sufficient for plasma membrane trafficking. Mutation at N445 severely impaired both ELFN1 and ELFN2 binding. All single mutants exhibited dendritic tip enrichment in rod BCs, as did the triple mutant with N445 as the sole N-glycosylation site, demonstrating that glycosylation at N445 is sufficient but not necessary for dendritic tip localization. The quadruple mutant was completely mislocalized. These results reveal a key role for complex N-glycosylation in regulating mGluR6 trafficking and ELFN binding, and by extension, function of the photoreceptor synapses.

A 53-year-old woman with a rapidly progressive, non-enhancing left frontotemporal lesion

Fifty-three-year-old woman presented with chronic, episodic headache.

Malignant Glioma

This chapter provides a comprehensive overview of malignant gliomas, the most common primary brain tumor in adults. These tumors are varied in their cellular origin, genetic profile, and morphology under the microscope, but together they share some of the most dismal prognoses of all neoplasms in the body. Although there is currently no cure for malignant glioma, persistent efforts to improve outcomes in patients with these tumors have led to modest increases in survival, and researchers worldwide continue to strive toward a deeper understanding of the factors that influence glioma development and response to treatment. In addition to well-established epidemiology, clinical manifestations, and common histopathologic and radiologic features of malignant gliomas, this section considers recent advances in molecular biology that have led to a more nuanced understanding of the genetic changes that characterize the different types of malignant glioma, as well as their implications for treatment. Beyond the traditional classification of malignant gliomas based on histopathological features, this chapter incorporates the World Health Organization's 2016 criteria for the classification of brain tumors, with special focus on disease-defining genetic alterations and newly established subcategories of malignant glioma that were previously unidentifiable based on microscopic examination alone. Traditional therapeutic modalities that form the cornerstone of treatment for malignant glioma, such as aggressive surgical resection followed by adjuvant chemotherapy and radiation therapy, and the studies that support their efficacy are reviewed in detail. This provides a foundation for additional discussion of novel therapeutic methods such as immunotherapy and convection-enhanced delivery, as well as new techniques for enhancing extent of resection such as fluorescence-guided surgery.

Benign and Malignant Tumors of the Pineal Region

Pineal region tumors fall into five broad categories: benign pineal region tumors, glial tumors, papillary tumors, pineal parenchymal tumors, and germ cell tumors. Genetic and transcriptional studies have identified key chromosomal alterations in germinomas (RUNDC3A, ASAH1, LPL) and in pineocytomas/pineoblastomas (DROSHA/DICER1, RB1). Pineal region tumors generally present with symptoms of hydrocephalus including nausea, vomiting, papilledema, and the classical Parinaud's triad of upgaze paralysis, convergence-retraction nystagmus, and light-near pupillary dissociation. Workup requires neuroimaging and tissue diagnosis via biopsy. In germinoma cases, diagnosis may be made based on serum or CSF studies for alpha-fetoprotein or beta-HCG making the preferred treatment radiosurgery, thereby preventing the need for unnecessary surgeries. Treatment generally involves three steps: CSF diversion in cases of hydrocephalus, biopsy through endoscopic or stereotactic methods, and open surgical resection. Multiple surgical approaches are possible for approach to the pineal region. The original approach to the pineal region was the interhemispheric transcallosal first described by Dandy. The most common approach is the supracerebellar infratentorial approach as it utilizes a natural anatomic corridor for access to the pineal region. The paramedian or lateral supracerebellar infratentorial approach is another improvement that uses a similar anatomic corridor but allows for preservation of midline bridging veins; this minimizes the chance for brainstem or cerebellar venous infarction. Determination of the optimal approach relies on tumor characteristics, namely location of deep venous structures to the tumor along with the lateral eccentricity of the tumor. The immediate post-operative period is important as hemorrhage or swelling can cause obstructive hydrocephalus and lead to rapid deterioration. Adjuvant therapy, whether chemotherapy or radiation, is based on tumor pathology. Improvements within pineal surgery will require improved technology for access to the pineal region along with targeted therapies that can effectively treat and prevent recurrence of malignant pineal region tumors.

Benign Glioma

Benign glioma broadly refers to a heterogeneous group of slow-growing glial tumors with low proliferative rates and a more indolent clinical course. These tumors may also be described as "low-grade" glioma (LGG) and are classified as WHO grade I or II lesions according to the Classification of Tumors of the Central Nervous System (CNS) (Louis et al. in Acta Neuropathol 114:97-109, 2007). Advances in molecular genetics have improved understanding of glioma tumorigenesis, leading to the identification of common mutation profiles with significant treatment and prognostic implications. The most recent WHO 2016 classification system has introduced several notable changes in the way that gliomas are diagnosed, with a new emphasis on molecular features as key factors in differentiation (Wesseling and Capper in Neuropathol Appl Neurobiol 44:139-150, 2018). Benign gliomas have a predilection for younger patients and are among the most frequently diagnosed tumors in children and young adults (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). These tumors can be separated into two clinically distinct subgroups. The first group is of focal, well-circumscribed lesions that notably are not associated with an increased risk of malignant transformation. Primarily diagnosed in pediatric patients, these WHO grade I tumors may be cured with surgical resection alone (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). Recurrence rates are low, and the prognosis for these patients is excellent (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). Diffuse gliomas are WHO grade II lesions with a more infiltrative pattern of growth and high propensity for recurrence. These tumors are primarily diagnosed in young adult patients, and classically present with seizures (Pallud et al. Brain 137:449-462, 2014). The term "benign" is a misnomer in many cases, as the natural history of these tumors is with malignant transformation and recurrence as grade III or grade IV tumors (Jooma et al. in J Neurosurg 14:356-363, 2019). For all LGG, surgery with maximal safe resection is the treatment of choice for both primary and recurrent tumors. The goal of surgery should be for gross total resection (GTR), as complete tumor removal is associated with higher rates of tumor control and seizure freedom. Chemotherapy and radiation therapy (RT), while not typically a component of first-line treatment in most cases, may be employed as adjunctive therapy in high-risk or recurrent tumors and in some select cases. The prognosis of benign gliomas varies widely; non-infiltrative tumor subtypes generally have an excellent prognosis, while diffusely infiltrative tumors, although slow-growing, are eventually fatal (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). This chapter reviews the shared and unique individual features of the benign glioma including diffuse glioma, pilocytic astrocytoma and pilomyxoid astrocytoma (PMA), subependymal giant cell astrocytoma (SEGA), pleomorphic xanthoastrocytoma (PXA), subependymoma (SE), angiocentric glioma (AG), and chordoid glioma (CG). Also discussed is ganglioglioma (GG), a mixed neuronal-glial tumor that represents a notable diagnosis in the differential for other LGG (Wesseling and Capper 2018). Ependymomas of the brain and spinal cord, including major histologic subtypes, are discussed in other chapters.

Thoracic low grade glial neoplasm with concurrent H3 K27M and PTPN11 mutations

We present the case of a 41-year-old man who developed worsening mid-thoracic back pain and imaging revealed a well-circumscribed intramedullary tumor in the thoracic spinal cord. Subtotal resection was performed, and histopathological analysis showed a cytologically bland, minimally proliferative glial neoplasm. Sequencing revealed H3 K27M and an activating PTPN11 mutation. Serial imaging revealed slow tumor regrowth over a three year period which prompted a second resection. The recurrent tumor displayed a similar low grade-appearing histology and harbored the same H3 K27M and PTPN11 mutations as the primary. While the prognostic importance of isolated H3 K27M in spinal gliomas is well-known, the combination of these two mutations in spinal low grade glioma has not been previously reported. Importantly, PTPN11 is a component of the MAPK signaling pathway. Thus, as building evidence shows that low grade-appearing gliomas harboring H3 K27M mutations along with BRAF or FGFR1 mutations have a relatively more favorable course compared to isolated H3 K27M-mutant midline gliomas, the present case provides new evidence for the prognostic importance of activating mutations in other components of the MAPK signaling pathway. This case further highlights the importance of clinico-radio-pathologic correlation when incorporating evolving genetic data into the integrated diagnosis of rare neuroepithelial tumors.

Pituitary corticotroph tumour with adrenocortical cells: A distinct clinicopathologic entity with unique morphology and methylation profile

We describe a rare TPIT-positive corticotroph PitNET that is admixed with SF1-positive adrenocortical cells. This dimorphous population of cells showed no colocalisation between TPIT and SF1 by immunofluorescence, and an adrenocortical choristoma was favoured. Methylation array analysis revealed a novel methylation profile in relation to other pituitary neoplasms.

COVID-19 neuropathology at Columbia University Irving Medical Center/New York Presbyterian Hospital

Many patients with SARS-CoV-2 infection develop neurological signs and symptoms; although, to date, little evidence exists that primary infection of the brain is a significant contributing factor. We present the clinical, neuropathological and molecular findings of 41 consecutive patients with SARS-CoV-2 infections who died and underwent autopsy in our medical centre. The mean age was 74 years (38-97 years), 27 patients (66%) were male and 34 (83%) were of Hispanic/Latinx ethnicity. Twenty-four patients (59%) were admitted to the intensive care unit. Hospital-associated complications were common, including eight patients (20%) with deep vein thrombosis/pulmonary embolism, seven (17%) with acute kidney injury requiring dialysis and 10 (24%) with positive blood cultures during admission. Eight (20%) patients died within 24 h of hospital admission, while 11 (27%) died more than 4 weeks after hospital admission. Neuropathological examination of 20-30 areas from each brain revealed hypoxic/ischaemic changes in all brains, both global and focal; large and small infarcts, many of which appeared haemorrhagic; and microglial activation with microglial nodules accompanied by neuronophagia, most prominently in the brainstem. We observed sparse T lymphocyte accumulation in either perivascular regions or in the brain parenchyma. Many brains contained atherosclerosis of large arteries and arteriolosclerosis, although none showed evidence of vasculitis. Eighteen patients (44%) exhibited pathologies of neurodegenerative diseases, which was not unexpected given the age range of our patients. We examined multiple fresh frozen and fixed tissues from 28 brains for the presence of viral RNA and protein, using quantitative reverse-transcriptase PCR, RNAscope® and immunocytochemistry with primers, probes and antibodies directed against the spike and nucleocapsid regions. The PCR analysis revealed low to very low, but detectable, viral RNA levels in the majority of brains, although they were far lower than those in the nasal epithelia. RNAscope® and immunocytochemistry failed to detect viral RNA or protein in brains. Our findings indicate that the levels of detectable virus in coronavirus disease 2019 brains are very low and do not correlate with the histopathological alterations. These findings suggest that microglial activation, microglial nodules and neuronophagia, observed in the majority of brains, do not result from direct viral infection of brain parenchyma, but more likely from systemic inflammation, perhaps with synergistic contribution from hypoxia/ischaemia. Further studies are needed to define whether these pathologies, if present in patients who survive coronavirus disease 2019, might contribute to chronic neurological problems.

Synchronous supratentorial and infratentorial oligodendrogliomas with incongruous IDH1 mutations, a case report

Infratentorial oligodendrogliomas, a rare pathological entity, are generally considered metastatic lesions from supratentorial primary tumors. Here, we report the case of a 23-year-old man presenting with a histopathologically confirmed right precentral gyrus grade 2 oligodendroglioma and a concurrent pontine grade 3 oligodendroglioma. The pontine lesion was biopsied approximately a year after the biopsy of the precentral lesion due to disease progression despite 4 cycles of procarbazine-CCNU-vincristine (PCV) chemotherapy and stable supratentorial disease. Histology and genetic analysis of the pontine biopsy were consistent with grade 3 oligodendroglioma, and comparison of the two lesions demonstrated common 1p/19q co-deletions and TERT promoter mutations but distinct IDH1 mutations, with a non-canonical IDH1 R132G mutation identified in the infratentorial lesion and a R132H mutation identified in the cortical lesion. Initiation of Temozolomide led to complete response of the supratentorial lesion and durable disease control, while Temozolomide with subsequent radiation therapy of 54 Gy in 30 fractions resulted in partial response of the pontine lesion. This case report supports possible distinct molecular pathogenesis in supratentorial and infratentorial oligodendrogliomas and raises questions about the role of different IDH1 mutant isoforms in explaining treatment resistance to different chemotherapy regimens. Importantly, this case suggests that biopsies of all radiographic lesions, when feasible and safe, should be considered in order to adequately guide management in multicentric oligodendrogliomas.

Erratum: Azimuthal Anisotropy of K_{S}^{0} and Λ+Λ[over ¯] Production at Midrapidity from Au+Au Collisions at sqrt[s]_{NN}=130 GeV [Phys. Rev. Lett. 89, 132301 (2002)]

This corrects the article DOI: 10.1103/PhysRevLett.89.132301.

Erratum: Azimuthal Anisotropy at the Relativistic Heavy Ion Collider: The First and Fourth Harmonics [Phys. Rev. Lett. 92, 062301 (2004)]

This corrects the article DOI: 10.1103/PhysRevLett.92.062301.

A Case of Pediatric Stroke: Osteosarcoma Embolus in the Internal Carotid Artery

Stroke in the pediatric population is rare. Despite presentation similar to that seen in the adult patient, the diagnosis in a child can be missed or mistaken for a more common stroke mimic. Due to its rarity, there are no completed pediatric clinical trials investigating best treatment, though guidelines have been extrapolated from adult guidelines and retrospective cohort studies to include some combination of thrombolysis and mechanical thrombectomy. Rarer still is pediatric stroke caused by tumor embolus. We present the case of a young child diagnosed with stroke secondary to osteosarcoma embolism to the left internal carotid artery and review the relevant literature to discuss the considerations and challenges of treatment of stroke in the pediatric population.

Biomarkers of endothelial dysfunction in cocaine overdose and overdose-related cardiovascular events

Overdose of stimulant drugs has been associated with increased risk of adverse cardiovascular events (ACVE), some of which may be ascribed to endothelial dysfunction. The aims of this study were to evaluate biomarkers of endothelial dysfunction in emergency department (ED) patients with acute cocaine overdose and to assess the association between in-hospital ACVE in ED patients with any acute drug overdose. This was a prospective consecutive cohort study over 9 months (2015-2016) at two urban, tertiary-care hospital EDs. Consecutive adults (≥18 years) presenting with suspected acute drug overdose were eligible and separated into three groups: cocaine (n = 47), other drugs (n = 128), and controls (n = 11). Data were obtained from medical records and linked to waste serum specimens, sent as part of routine clinical care, for biomarker analysis. Serum specimens were collected and analyzed using enzyme-linked immunosorbent assay kit for three biomarkers of endothelial dysfunction: (a) endothelin-1 (ET-1), (b) regulated upon activation normal T cell expressed and secreted (RANTES), and (c) soluble intercellular adhesion molecule-1 (siCAM-1). Mean siCAM was elevated for cocaine compared with controls and other drugs (p < .01); however, mean RANTES and ET-1 levels were not significantly different for any drug exposure groups. Receiver operating characteristics curve analysis for prediction of in-hospital ACVE revealed excellent performance of siCAM-1 (area under curve, 0.86; p < .001) but lack of predictive utility for either RANTES or ET-1. These results suggest that serum siCAM-1 is a viable biomarker for acute cocaine overdose and that endothelial dysfunction may be an important surrogate for adverse cardiovascular events following any drug overdose.

Antibody Co-Administration Can Improve Systemic and Local Distribution of Antibody-Drug Conjugates to Increase In Vivo Efficacy

Several antibody-drug conjugates (ADC) showing strong clinical responses in solid tumors target high expression antigens (HER2, TROP2, Nectin-4, and folate receptor alpha/FRα). Highly expressed tumor antigens often have significant low-level expression in normal tissues, resulting in the potential for target-mediated drug disposition (TMDD) and increased clearance. However, ADCs often do not cross-react with normal tissue in animal models used to test efficacy (typically mice), and the impact of ADC binding to normal tissue antigens on tumor response remains unclear. An antibody that cross-reacts with human and murine FRα was generated and tested in an animal model where the antibody/ADC bind both human tumor FRα and mouse FRα in normal tissue. Previous work has demonstrated that a "carrier" dose of unconjugated antibody can improve the tumor penetration of ADCs with high expression target-antigens. A carrier dose was employed to study the impact on cross-reactive ADC clearance, distribution, and efficacy. Co-administration of unconjugated anti-FRα antibody with the ADC-improved efficacy, even in low expression models where co-administration normally lowers efficacy. By reducing target-antigen-mediated clearance in normal tissue, the co-administered antibody increased systemic exposure, improved tumor tissue penetration, reduced target-antigen-mediated uptake in normal tissue, and increased ADC efficacy. However, payload potency and tumor antigen saturation are also critical to efficacy, as shown with reduced efficacy using too high of a carrier dose. The judicious use of higher antibody doses, either through lower DAR or carrier doses, can improve the therapeutic window by increasing efficacy while lowering target-mediated toxicity in normal tissue.

Use of PROMIS® to screen for depression in children with arthritis

BACKGROUND

Children with JIA may experience difficulty with health related quality of life (HRQOL). The Patient Reported Outcomes Measurement Information System (PROMIS) a patient related outcome (PRO) measure, covers HRQOL domains that include physical function, mental health, and social interactions. During initial use, we found PROMIS identified children with symptoms of depression, sometimes before they shared those feelings with parents or members of the clinic team. We studied the use of PROMIS for this purpose, and to determine what demographic, clinical, and other characteristics might be related to higher depressive symptom scores.

METHODS

From March 2014 - February 2017, at each visit, all JIA patients having met ILAR classification criteria seen by M.L.M. received the PROMIS Short Form 35 v.1.0, as part of routine care. T scores were calculated from raw scores for mobility, anxiety, depressive symptoms, fatigue, peer relationships, and pain interference domains. Data extracted by optical mark recognition software were merged with electronic medical record (EMR data), extracted by Extract/Transform/Load software, including joint counts, visit age, ANA, RF, and HLA-B27 status. Mixed effects models were used to identify significant associations of independent variables with depression T scores.

RESULTS

Data from 148 patients were analyzed (114 females for 435 visits, 34 males for 118 visits; 13.8 ± 2.8 years): 70 persistent oligoarthritis, 9 extended oligoarthritis, 19 ERA, 21 polyarthritis (RF-), 5 polyarthritis (RF+), 11 undifferentiated arthritis, 3 psoriatic arthritis, 10 systemic arthritis). T scores showed wide ranges within individual JIA categories, with similar mean scores for all groups. Univariate linear mixed effects models showed significant relationships to depression T scores of gender and race (males and Asian patients with lower T scores, p < .0001, p = 0.091, respectively), joint count (p = 0.002), pain interference score (p = 0.0004), and Patient and Physician Global Assessment (p = 0.004, p < .0001, respectively). No particular JIA category was associated with Depression T scores. HRQOL domains were interrelated (p < .0001), including patients reporting symptoms of depression tending also to report symptoms of anxiety. PROMIS identified 15 patients who did not otherwise report depressive symptoms, but needed referral for counseling; eight did not endorse depressive symptoms until the 2nd or 3rd visit. Only 3 patients had disease flare. Concerns besides arthritis such as parental conflict or school bullying were elicited in 7 patients during interviews with the social worker. All patients expressed being worried about their arthritis.

CONCLUSION

PROMIS is useful in screening JIA patients for symptoms of depression, particularly to identify patients who might not otherwise report these symptoms. The other PROMIS domain scores are related to reporting of symptoms of depression, as is Patient and Physician Global Assessment. Future studies will use PROMIS questionnaires incorporated into the EMR, permitting data entry by tablets and an online patient portal. This will make possible comparisons of HRQOL in children with JIA to those with other chronic rheumatic and non-rheumatic diseases.

Short-term biological variation of serum thyroid hormones concentrations in clinically healthy cats

Thyroid disease is common in cats, but little is known about the biologic variability of serum thyroid hormone concentrations and its impact on diagnostic utility in either healthy cats or cats with thyroid disease. The purpose of this study was to determine the biological variation, index of individuality, and reference change values for thyroid hormones and thyroid-stimulating hormone (TSH) in clinically healthy cats. Serum samples for analysis of total thyroxine (T₄), triiodothyronine (T₃), free T₄ by dialysis, and TSH were obtained weekly for 6 wk from 10 healthy cats, then frozen until single-batch analyzed. Data were evaluated for outliers, and we determined the CV within individual cats (CV_I) and between individual cats (CV_G) for each hormone and the variation between duplicates or analytical variation (CV_A). The index of individuality and reference change values for each hormone were then calculated. Serum concentrations of total T₄, free T₄, T₃, and TSH all showed greater variation between cats (CV_G) than within cats (CV_I). Total and free T₄ had an intermediate index of individuality (1.1 and 1.2, respectively), suggesting that these hormones would be best evaluated by a combination of their population-based reference intervals and reference change values. Serum TSH concentrations had high index of individuality (1.8), suggesting this hormone would be best evaluated with reference change values rather than the population-based reference interval. Total T₃ also had a high calculated index of individuality (1.8); however, T₃ had high ratio of analytical variation (CV_A) to within cat variation (CV_I), so RCV could not be accurately calculated. This study demonstrates that clinically normal cats show considerable interindividual biological variation in serum thyroid hormone and TSH concentrations, whereas the intraindividual variability in hormone concentrations is much narrower. This suggests that for all serum thyroid hormones, but especially serum TSH and T₃ concentrations, comparing individual cat's hormone results to a population-based reference interval may be misleading, especially in those with early or subclinical thyroid disease. Clinicians might improve the diagnosis of feline thyroid disease by establishing baseline concentrations of T₄, free T₄, T₃, and TSH for individual cats (ideally when healthy) and applying reference change values to subsequent measurements.

Detection of Nonhematologic Neoplasms by Routine Flow Cytometry Analysis

OBJECTIVES

We investigated the ability of routine flow cytometry (FC) to detect nonhematologic neoplasms (non-HN) using antibody panels routinely used for the diagnosis of hematologic neoplasms.

METHODS

FC analyses of 4,000 various diagnostic samples were retrospectively reviewed to identify cases in which an aberrant, viable CD45-negative, nonhematologic neoplastic population was detected by FC panels designed to evaluate hematologic neoplasms.

RESULTS

A total of 57 (1.4%) diverse non-HNs were identified, representing neuroendocrine tumors (33/57) and carcinomas (9/57), as well as other malignancies (15/57) such as sarcoma and melanoma. The majority of neoplasms were positive for at least one antibody, typically CD56 (43/51, 84.3%), followed by CD117 (15/34, 44.1%) and CD138 (6/33, 18.2%).

CONCLUSIONS

Our findings highlight the importance of carefully inspecting CD45-negative events to identify non-HNs by routine FC analysis. This can help expedite further downstream immunophenotypic analysis of specimens and triage samples for appropriate genetic and molecular studies.

Site-Specific Conjugation of the Indolinobenzodiazepine DGN549 to Antibodies Affords Antibody-Drug Conjugates with an Improved Therapeutic Index as Compared with Lysine Conjugation

Antibody-drug conjugates have elicited great interest recently as targeted chemotherapies for cancer. Recent preclinical and clinical data have continued to raise questions about optimizing the design of these complex therapeutics. Biochemical methods for site-specific antibody conjugation have been a design feature of recent clinical ADCs, and preclinical reports suggest that site-specifically conjugated ADCs generically offer improved therapeutic indices (i.e., the fold difference between efficacious and maximum tolerated doses). Here we present the results of a systematic preclinical comparison of ADCs embodying the DNA-alkylating linker-payload DGN549 generated with both heterogeneous lysine-directed and site-specific cysteine-directed conjugation chemistries. Importantly, the catabolites generated by each ADC are the same regardless of the conjugation format. In two different model systems evaluated, the site-specific ADC showed a therapeutic index benefit. However, the therapeutic index benefit is different in each case: both show evidence of improved tolerability, though with different magnitudes, and in one case significant efficacy improvement is also observed. These results support our contention that conjugation chemistry of ADCs is best evaluated in the context of a particular antibody, target, and linker-payload, and ideally across multiple disease models.

Antibody-Drug Conjugates with Indolinobenzodiazepine Dimer Payloads: DNA-Binding Mechanism of Indolinobenzodiazepine Dimer Catabolites in Target Cancer Cells

DNA-targeting indolinobenzodiazepine dimer (IGN) payloads are used in several clinical-stage antibody-drug conjugates. IGN drugs alkylate DNA through the single imine moiety present in the dimer in contrast to the pyrrolobenzodiazepine dimer drugs, such as talirine and tesirine, which contain two imine moieties per dimer and cross-link DNA. This study explored the mechanism of binding of IGN to DNA in cells and to synthetic duplex and hairpin oligonucleotides. New, highly sensitive IGN-DNA binding enzyme-linked immunosorbent assay methods were developed using biotinylated IGN analogues (monoimine, diimine, and diamine IGNs) and digoxigenin-labeled duplex oligonucleotides, which allowed the measurement of drug-DNA adducts in viable cells at concentrations below IC₅₀. Furthermore, the release of free drug from the IGN-DNA adduct upon treatment with nuclease ex vivo was tested under physiological conditions. The monoimine IGN drug formed a highly stable adduct with DNA in cells, with stability similar to that of the diimine drug analogue. Both monoimine and diimine IGN-DNA adducts released free drugs upon DNA cleavage by nuclease at 37 °C, although more free drug was released from the monoimine compared to the diimine adduct, which presumably was partly cross-linked. The strong binding of the monoimine IGN drug to duplex DNA results from both the noncovalent IGN-DNA interaction and the covalent bond formation between the 2-amino group of a guanine residue and the imine moiety in IGN.

Design, synthesis and evaluation of novel, potent DNA alkylating agents and their antibody-drug conjugates (ADCs)

Antibody-drug conjugates (ADCs) incorporating potent indolinobenzodiazepine (IGN) DNA alkylators as the cytotoxic payload are currently undergoing clinical evaluation. The optimized design of these payloads consists of an unsymmetrical dimer possessing both an imine and an amine effectively eliminating DNA crosslinking and demonstrating improved tolerability in mice. Here we present an alternate approach to generating DNA alkylating ADCs by linking the IGN monomer with a biaryl system which has a high DNA binding affinity to potentially enhance tolerability. These BIA ADCs were found to be highly cytotoxic in vitro and demonstrated potent antitumor activity in vivo.

Rituximab-associated Hypogammaglobulinemia in pediatric patients with autoimmune diseases

BACKGROUND

Despite the increased use of rituximab in treating pediatric patients with autoimmune diseases in the last decade, there are limited data on rituximab safety in those subjects who have a developing immune system. The objective of this study is to determine the prevalence of hypogammaglobulinemia in children with autoimmune disease receiving rituximab within the first three years of treatment in the pediatric rheumatology clinic at a tertiary care center.

METHODS

We conducted a retrospective chart review of 63 pediatric subjects who received rituximab for the treatment of their autoimmune disease. Immunoglobulin gamma (IgG) levels, immunosuppressive medication and the need for immunoglobulin replacement therapy were evaluated. Hypogammaglobulinemia was defined as a serum IgG level less than two standard deviations below the mean for age-matched healthy controls.

RESULTS

Twenty-eight patients (44%) were found to have hypogammaglobulinemia. Hypogammaglobulinemia occurred within the first six months of rituximab treatment in the majority of patients (22 out of 28). The occurrence of hypogammaglobulinemia varied based on the rituximab indication: 46% pediatric Systemic Lupus Erythematosus (SLE), 71% autoimmune CNS disease, 60% ANCA vasculitis, and 12% in the miscellaneous group. Autoimmune CNS disease had more severe hypogammaglobulinemia, more persistent and was associated with more frequent or severe infections. Three patients with autoimmune CNS disease and one with SLE were given IgG replacement therapy to prevent recurrent or severe infections.

CONCLUSIONS

The prevalence of hypogammaglobulinemia in rituximab treated children with autoimmune disease seems to be higher than published data for adults, especially for children with autoimmune CNS disease. The onset of hypogammaglobulinemia is usually within six months of initiation of rituximab therapy. We recommend: 1) obtaining an IgG level prior to starting rituximab; 2) close monitoring for hypogammaglobulinemia after the use of rituximab in pediatric patients and 3) early institution of immunoglobulin replacement therapy if patients develop recurrent infections.

Synthesis of Highly Potent N-10 Amino-Linked DNA-Alkylating Indolinobenzodiazepine Antibody-Drug Conjugates (ADCs)

Indolinobenzodiazepine DNA alkylators (IGNs) are the cytotoxic payloads in antibody-drug conjugates (ADCs) currently undergoing Phase I clinical evaluation (IMGN779, IMGN632, and TAK164). These ADCs possess linkers that have been incorporated into a central substituted phenyl spacer. Here, we present an alternative strategy for the IGNs, linking through a carbamate at the readily available N-10 amine present in the monoimine containing dimer. As a result, we have designed a series of N-10 linked IGN ADCs with a wide range of in vitro potency and tolerability, which may allow us to better match an IGN with a particular target based on the potential dosing needs.

Effect of Linker Stereochemistry on the Activity of Indolinobenzodiazepine Containing Antibody-Drug Conjugates (ADCs)

Antibody-drug conjugates (ADCs) that incorporate potent indolinobenzodiazepine DNA alkylators as the payload component are currently undergoing clinical evaluation. In one ADC design, the payload molecules are linked to the antibody through a peptidase-labile l-Ala-l-Ala linker. In order to determine the role of amino acid stereochemistry on antitumor activity and tolerability, we incorporated l- and d-alanyl groups in the dipeptide, synthesized all four diastereomers, and prepared and tested the corresponding ADCs. Results of our preclinical evaluation showed that the l-Ala-l-Ala configuration provided the ADC with the highest therapeutic index (antitumor activity vs toxicity).

Abstract 231: Optimizing lysosomal activation of antibody-drug conjugates (ADCs) by incorporation of novel cleavable dipeptide linkers

Peptides constitute a major linker class in antibody-drug conjugates (ADCs), designed to connect antibodies to cytotoxic drug molecules. An optimal linker for an ADC should be stable in circulation and be cleaved efficiently in lysosomes upon binding and internalization of the ADC in target cells, releasing drug molecules that exit lysosomes and inhibit key cellular functions. Previous studies have focused on a limited selection of peptide linkers and specific biochemical tools, such as a cathepsin B cleavage assay, leading to the selection of a valine-citrulline dipeptide linker with a p-aminobenzyloxycarbonyl (PABC) spacer, which is now often used in candidate ADCs.

In this study, we screened a panel of dipeptide linkers for efficient lysosomal proteolysis. Dipeptide linkers bearing different amino acids (typically both L, with D used as a control) were synthesized with a fluorogenic leaving group, 7-amino-4-methylcoumarin, which provided a convenient model system for screening of peptide cleavage using lysosomal extracts from cancer cells as well as several individual cathepsins. The linkers were also tested for stability in mouse, rat, cynomolgus, and human plasma.

Based on these screens, we identified several novel, previously unreported peptide linker designs and incorporated them into ADCs bearing a DNA-alkylating indolinobenzodiazepine (IGN) payload. These ADCs with different peptide linkers were assayed for in vitro cytotoxicity in multiple cancer cell lines, in vivo efficacy in human tumor xenograft models in mice, and ex vivo plasma stability. In addition, we measured the impact of peptide linkers on the kinetics of proteolytic processing of ADCs in cancer cell lines. We observed that several dipeptide linker designs were superior in rates of lysosomal processing compared to a reference standard L-Ala-L-Ala dipeptide linker.

Citation Format: Paulin Salomon, Luke Harris, Emily E. Reid, Erin K. Maloney, Alan J. Wilhelm, Michael L. Miller, Ravi V. Chari, Thomas A. Keating, Rajeeva Singh. Optimizing lysosomal activation of antibody-drug conjugates (ADCs) by incorporation of novel cleavable dipeptide linkers [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 231.

Abstract 230: Antibody-drug conjugates (ADCs) with indolinobenzodiazepine dimer (IGN) payloads: DNA-binding mechanism of IGN catabolites in target cancer cells

A DNA-interacting indolinobenzodiazepine dimer (IGN) payload was designed with a single reactive imine group towards the goal of eliminating DNA cross-linking and avoiding related toxicities, while conferring a strong binding of the IGN scaffold to duplex DNA. Several IGN ADCs, wherein the payload is linked via a peptide or hindered disulfide, are currently being evaluated in the clinic. In contrast to our lead IGNs, DNA-interacting pyrrolobenzodiazepine (PBD)-based ADC payloads, such as talirine and tesirine, contain two reactive imine groups that can cross-link DNA.

Here, we investigated the mechanism of binding of IGN catabolites with DNA in target cancer cells, and with model duplex DNA or hairpin oligonucleotides. Hairpin and duplex oligonucleotides, designed for high melting temperatures (around 50-60 °C), were custom synthesized with labels. Model IGN catabolites bearing a single imine (mono-imine) or two imine groups (di-imine) were synthesized with a biotin label. Sensitive assays were developed to measure IGN-DNA binding in cells at sub-cytotoxic concentrations (lower than IC50) to allow studies of DNA adduct stability and repair.

The mono-imine IGN molecules bind readily to oligonucleotides, generating stable adducts as determined by gel filtration and reversed phase HPLC analysis. To investigate the binding of unconjugated IGNs with cellular DNA, cancer cells were incubated with mono- and di-imine IGNs for a short-term, followed by wash and further incubation in fresh media. Both mono-and di-imine IGN molecules remained bound to genomic DNA even at 2 days, suggesting a potent interaction with cellular DNA. The time course of binding of IGN to DNA in cells was slower than that observed with model oligonucleotides, as expected because the tightly coiled cellular DNA presumably binds IGN only after the unwinding of DNA during cell cycle or transcription.

Upon DNA cleavage by an added nuclease, free IGN was released from IGN adducts of model oligonucleotides and from genomic DNA of cells that had been treated with unconjugated IGN or IGN ADC. This dissociation of IGN from IGN-DNA adducts only upon cleavage with nuclease suggests that a strong non-covalent interaction between IGN and duplex DNA stabilizes the adduct. The amount of free IGN released from cellular DNA adduct upon nuclease treatment was about 2-fold greater for mono-imine IGN than di-imine IGN, presumably because di-imine IGN was partly cross-linked to cellular DNA. Mono-imine IGN-DNA adducts could potentially be repaired by cellular endonucleases via a DNA cleavage mechanism. In conclusion, the mono-imine IGN payload molecules form highly stable adducts with DNA, which dissociate upon DNA cleavage at physiological temperature.

Citation Format: Rajeeva Singh, Luke Harris, Paulin Salomon, Emily E. Reid, Michael L. Miller, Ravi V. Chari, Thomas A. Keating. Antibody-drug conjugates (ADCs) with indolinobenzodiazepine dimer (IGN) payloads: DNA-binding mechanism of IGN catabolites in target cancer cells [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 230.

Abstract 224: Antibody-drug conjugates (ADCs) of a new class of N-10 amino linked DNA alkylating indolino-benzodiazepines (IGNs)

We have previously reported on our antibody-drug conjugates (ADCs) that incorporate a highly potent novel DNA alkylating indolino-benzodiazepine (termed IGN) dimer. ADCs of these DNA alkylating IGNs were found preclinically to demonstrate better tolerability and an improved overall therapeutic index (TI) compared with those of the corresponding DNA crosslinking IGNs (Miller, et al., Mol. Cancer Ther. 2016, 2018). IGN-containing ADCs that have reached the clinical stage bear DNA alkylating IGN compounds linked to the antibody via a cleavable linker, incorporated at the amino group of a centrally located anilino spacer moiety. In our ongoing effort to further explore the structure-activity relationship (SAR) of DNA alkylating effector molecules for ADCs, we disclose here a new class of IGNs possessing a self-immolative peptide linker attached at the N-10 amine of the imine-reduced IGN monomer subunit. We explored the impact of modifying the central spacer group connecting the IGN monomers, and site of linkage on in vitro potency and the interaction with DNA. A set of IGN molecules that met our potency criteria were identified and linkable forms of these compounds were prepared and conjugated to a folate receptor-α (FRα)-binding antibody. These ADCs displayed potent, antigen-specific in vitro activity across a panel of FRα-expressing cell lines. A lead ADC selected for in vivo studies demonstrated high stability in plasma and potent efficacy in various xenograft models, at doses well below the maximum tolerated dose. Thus, IGNs modified with an N-10 self-immolative peptide linker are promising DNA alkylating effector molecules for use in ADCs.

Citation Format: Michael L. Miller, Emily E. Reid, Katie E. Archer, Luke Harris, Erin K. Maloney, Laura M. Bartle, Olga Ab, Alan J. Wilhelm, Jose F. Ponte, Rajeeva Singh, Thomas A. Keating, Ravi V. Chari. Antibody-drug conjugates (ADCs) of a new class of N-10 amino linked DNA alkylating indolino-benzodiazepines (IGNs) [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 224.

Practical Bioinformatic DNA-Sequencing Pipeline for Detecting Oncogene Amplification and EGFRvIII Mutational Status in Clinical Glioblastoma Samples

Glioblastoma is a malignant brain tumor with dismal prognosis. Oncogenic mutations in glioblastoma frequently affect receptor tyrosine kinase pathway components that are challenging to quantify because of heterogeneous expression. EGFRvIII, a common oncogenic receptor tyrosine kinase mutant protein in glioblastoma, potentiates tumor malignancy and is an emerging tumor-specific immunotarget, underlining the need for its more accessible and quantitative detection. We used normalized next-generation sequencing data from 117 brain and 371 reference clinical tumor samples to detect focal gene amplifications across the commercial Ion AmpliSeq Cancer Hotspot Panel version 2 and infer EGFRvIII status based on relative coverage dropout of the gene's truncated region within EGFR. In glioblastomas (n = 45), amplification of EGFR [18 (40%)], PDGFRA [3 (7%)], KIT [2 (4%)], MET [1 (2%)], and AKT1 [1 (2%)] was detected. With respect to EGFR and PDGFRA amplification, there was near-complete agreement between next-generation sequencing and in situ hybridization. Consistent with previous reports, this method detected EGFRvIII exclusively in EGFR-amplified glioblastomas [8 (44%)], which was confirmed using long-range PCR. Our study offers a practical method for detecting oncogene amplifications and large intragenic mutations in a clinically implemented hotspot panel that can be quantified using z scores. The validated detection of EGFRvIII using DNA sequencing eliminates problems with transcript degradation, and the provided script facilitates efficient incorporation into a laboratory's bioinformatic pipeline.

Total Sleep Time and BMI z-score Are Associated With Physical Function Mobility, Peer Relationship, and Pain Interference in Children Undergoing Routine Polysomnography: A PROMIS Approach

INTRODUCTION

Sleep disturbance, especially obstructive sleep apnea (OSA) and inadequate sleep, adversely affect various health-related quality of life (HR-QoL) domains in adults. Few studies have addressed problems with HR-QoL in children with OSA or sleep-related symptoms.

METHODS

Patients between ages 5 to 17 years who were referred to the sleep laboratory from June 2017 to August 2017 for overnight polysomnography were approached to participate in the study.

RESULTS

A total of 86 patients were included in the final analysis; 45 patients (52.3%) were male; and the median (interquartile range) of their mean BMI z-scores was 1.7 (0.5, 2.4). The patients were categorized by OSA severity as follows: 27 (31.4%) mild OSA, 11 (12.8%) moderate OSA, 24 (27.9%) severe OSA, and 24 (27.9%) without OSA. Severity of OSA was not correlated with any PROMIS domain. In univariable analyses, BMI z-score was negatively correlated with physical function mobility score (P = .002) and positively correlated with pain interference (P = .02) and pain intensity (P = .02). Total sleep time was positively correlated with physical function mobility (P = .03) and peer relationship (P = .002). Significant correlations between several PROMIS domains were also observed.

CONCLUSIONS

Total sleep time was associated with physical function mobility and peer relationship. Regression analysis demonstrated a relationship between BMI z-score, physical function mobility, and pain intensity in our study population.

COMMENTARY

A commentary on this article appears in this issue on page 541.

Abstract 747: A new class of DNA alkylating indolino-benzodiazepine agents (BIAs) linked with a DNA binding moiety for use with antibody-drug conjugates (ADCs)

We have previously disclosed antibody-drug conjugates (ADCs) that incorporate our highly potent novel DNA alkylating indolino-benzodiazepine (termed IGN) pseudo dimer. ADCs of these DNA alkylating IGNs were found preclinically to demonstrate better tolerability and an improved overall therapeutic index (TI) compared with those of DNA crosslinking IGNs (Miller, et al., AACR 2017 #53). In our ongoing effort to further explore DNA alkylating effector molecules for ADCs, we disclose here a new class of IGNs (termed BIAs) in which one IGN monomer subunit is connected to a bis-aryl moiety with affinity for the DNA binding pocket. Our initial structure activity relationship (SAR) studies around a series of BIAs identified a set of scaffolds that met our requirement for high in vitro potency. These scaffolds were subsequently modified to incorporate functionalities that allow linkage to an antibody using various linker chemistries. These linkable BIAs displayed high in vitro potency across a panel of cell lines, indicating that the incorporation of a linker was not detrimental to their overall potency. Furthermore, we found that the potency of these linkable BIAs could be modulated by careful selection of substituents on the bis-aryl moiety providing enhanced binding affinity with DNA. Upon identification of lead BIA molecules, conjugates with a folate receptor-α (FRα)-binding antibody were prepared. These ADCs displayed potent, antigen-specific in vitro activity across a panel of FRα-expressing cell lines. In vivo, these ADCs demonstrated potent efficacy in xenograft models at doses well below the maximum tolerated dose. In light of these findings, BIA ADCs represent a promising new class of DNA alkylating effector molecules for use in the development of ADCs.

Citation Format: Michael L. Miller, Emily E. Reid, Katie E. Archer, Manami Shizuka, Molly A. McShea, Erin K. Maloney, Olga Ab, Leanne Lanieri, Alan J. Wilhelm, Jose F. Ponte, Nicholas C. Yoder, Ravi V. Chari. A new class of DNA alkylating indolino-benzodiazepine agents (BIAs) linked with a DNA binding moiety for use with antibody-drug conjugates (ADCs) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 747.

Search for Neutrinoless Double-β Decay in ^{76}Ge with the Majorana Demonstrator

The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-β decay in ^{76}Ge. The Majorana Demonstrator comprises 44.1 kg of Ge detectors (29.7 kg enriched in ^{76}Ge) split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. Here we present results from data taken during construction, commissioning, and the start of full operations. We achieve unprecedented energy resolution of 2.5 keV FWHM at Q_{ββ} and a very low background with no observed candidate events in 9.95 kg yr of enriched Ge exposure, resulting in a lower limit on the half-life of 1.9×10^{25}  yr (90% C.L.). This result constrains the effective Majorana neutrino mass to below 240-520 meV, depending on the matrix elements used. In our experimental configuration with the lowest background, the background is 4.0_{-2.5}^{+3.1}  counts/(FWHM t yr).

Treatment of canine sinonasal aspergillosis with clotrimazole infusion in patients with cribriform plate lysis

OBJECTIVE

To describe the treatment of sinonasal aspergillosis with topical 1% clotrimazole solution in dogs with cribriform plate lysis.

MATERIALS AND METHODS

This retrospective study includes data retrieval from medical records of dogs with sinonasal aspergillosis and cribriform plate lysis that underwent topical treatment with 1% clotrimazole solution.

RESULTS

Five dogs with sinonasal aspergillosis, cribriform plate lysis diagnosed on CT scans, and normal neurologic examinations were treated with a single (n=3) or multiple (n=2) infusions of clotrimazole solution. No dogs developed clinical neurologic disease after therapy.

CLINICAL SIGNIFICANCE

In this study, a topical clotrimazole solution was not associated with adverse neurologic effects in neurologically normal dogs with sinonasal aspergillosis and cribriform plate lysis.

Abstract 53: Antibody-drug conjugates (ADCs) of peptide-linked Indolino-Benzodiazepine (IGN) DNA-alkylator provides improved anti-tumor activity over that of a crosslinker

We recently disclosed highly active antibody-drug conjugates (ADCs) that incorporated the novel DNA alkylating indolino-benzodiazepine (termed IGN) dimer, DGN549 (IGN-P1). The stereochemistry of the alanyl moiety of the protease-cleavable alanine-alanine linker used was shown to impact ADC catabolism, bystander killing activity, and in vivo efficacy (Shizuka, et al., AACR 2016 #2959). Building upon these results, here we describe preclinical results from a head-to-head comparison of ADCs of the mono-imine containing DGN549 with its corresponding DNA cross-linking diimine version, IGN-P1 diimine. IGN-P1 diimine and DGN549 were conjugated to a folate receptor-α (FRα)-binding antibody and an EpCAM-binding antibody. The resulting ADCs demonstrated similar high in vitro potency (IC50 ~3-100 pM) and specificity towards several cancer cell lines. Further in vitro studies revealed that the DNA alkylating anti-FRα-DGN549 ADC demonstrated superior bystander cell-killing activity compared to its DNA crosslinking counterpart, anti-FRα-IGN-P1 diimine. In vivo, this improved bystander killing ability translated into better in vivo activity for the DNA alkylating ADC. In an endometrial tumor xenograft model established with Ishikawa cells, the anti-FRα-DGN549 induced complete regressions at a single dose of 140 µg/kg Ab dose (equivalent to 5 µg/kg linked IGN). The cross-linking anti-FRα-IGN-P1 diimine had to be used at twice the dose to achieve the same level of anti-tumor activity. The in vivo tolerability in CD-1 mice also displayed differences in the two ADCs. We found that the ADC of the DNA crosslinker was at least two-fold less tolerated than the corresponding ADC of the DNA alkylator. These results indicate that a ~4 fold greater therapeutic index can be achieved when using a DNA alkylating mono-imine DGN549 ADC as compared to the DNA crosslinking IGN-P1 diimine ADC.

Citation Format: Michael L. Miller, Manami Shizuka, Jose F. Ponte, Leanne Lanieri, Dilrukshi Vitharana, Qifeng Qiu, Emily E. Reid, Katie E. Archer, Rui Wu, Erin K. Maloney, Olga Ab, Jan Pinkas, Ravi V. Chari. Antibody-drug conjugates (ADCs) of peptide-linked Indolino-Benzodiazepine (IGN) DNA-alkylator provides improved anti-tumor activity over that of a crosslinker [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 53. doi:10.1158/1538-7445.AM2017-53

Thyroid Cysts in Cats: A Retrospective Study of 40 Cases

Background

Thyroid cysts are rare in cats and poorly documented.

Objectives

To report distinguishing clinical features and treatment responses of cats with thyroid cysts.

Animals

Forty client‐owned cats.

Methods

Retrospective review of medical records for cats with thyroid cysts confirmed by scintigraphy, ultrasound, magnetic resonance imaging, or necropsy at 4 referral centers between 2005 and 2016. Signalment, clinical findings, diagnostic testing, treatment, and outcome were recorded.

Results

Cats ranged in age from 8 to 20 years with no apparent breed or sex predilection. 37 of 40 (93%) cats were hyperthyroid (duration, 1–96 months). Clinical findings included palpable neck mass (40/40, 100%), weight loss (15/40, 38%), dysphagia (8/40, 20%), decreased appetite (5/40, 13%), and dyspnea (4/40, 10%). Cysts were classified as small (≤8 cm³) in 16 (40%) and large (>8 cm³) in 24 (60%) cats. Of 25 cats treated with radioiodine, hyperthyroidism resolved in 23 (92%), whereas thyroid cysts resolved in 12 (50%). Radioiodine treatment resolved small cysts in 8 of 13 (62%) cats and large cysts in 4 of 11 (36%) cats. Eight cats, including 2 euthyroid cats, underwent thyroid‐cystectomy; 3 with bilateral thyroid involvement were euthanized postoperatively for hypocalcemia. Excised cystic thyroid masses were identified as cystadenoma (4) and carcinoma (4).

Conclusions and Clinical Importance

Thyroid cysts are encountered in hyperthyroid and euthyroid cats with benign and malignant thyroid tumors. Radioiodine treatment alone inconsistently resolved thyroid cysts. Thyroid‐cystectomy could be considered in cats with unilateral thyroid disease or when symptomatic cysts persist despite successful radioiodine treatment of hyperthyroidism.

Automated data extraction: merging clinical care with real-time cohort-specific research and quality improvement data

BACKGROUND/PURPOSE

Although prohibitively labor intensive, manual data extraction (MDE) is the prevailing method used to obtain clinical research and quality improvement (QI) data. Automated data extraction (ADE) offers a powerful alternative. The purposes of this study were to 1) assess the feasibility of ADE from provider-authored outpatient documentation, and 2) evaluate the effectiveness of ADE compared to MDE.

METHODS

A prospective collection of data was performed on 90 ADE-templated notes (N=71 patients) evaluated in our bowel management clinic. ADE captured data were compared to 59 MDE notes (N=51) collected under an IRB-exempt review. Sixteen variables were directly comparable between ADE and MDE.

RESULTS

MDE for 59 clinic notes (27 unique variables) took 6months to complete. ADE-templated notes for 90 clinic notes (154 unique variables) took 5min to run a research/QI report. Implementation of ADE included eight weeks of development and testing. Pre-implementation clinical documentation was similar to post-implementation documentation (5-10min).

CONCLUSIONS

ADE-templated notes allow for a 5-fold increase in clinically relevant data that can be captured with each encounter. ADE also results in real-time data extraction to a research/QI database that is easily queried. The immediate availability of these data, in a research-formatted spreadsheet, allows for rapid collection, analyses, and interpretation of the data.

LEVEL OF EVIDENCE

IV.

TYPE OF STUDY

Retrospective Study.

Abstract 2960: Potent in vivo activity of site-specific indolino-benzodiazepine antibody-drug conjugates (ADCs) generated via engineered cysteine conjugation

ADCs are widely studied for cancer therapy, with numerous agents in preclinical and clinical development embodying a wide array of targets, linker chemistries, and cytotoxic effector classes. A fourth element of ADC design that has received much attention recently is the site of conjugation of the cytotoxic molecule to the antibody. Historically, lysine- or interchain cysteine-directed conjugation has been used, but site-specific chemistries have become increasingly popular. Our previous evaluation of site-specific and lysine-linked ADCs utilizing a tubulin-acting maytansinoid effector molecule found the lysine-linked version was more active in vivo (Yoder et al., AACR 2015 #645). Here we present a comparison of engineered cysteine site-specific and lysine-linked ADCs utilizing the previously described indolino-benzodiazepine (henceforth referred to as IGN) effector IGN-P1 (Miller et al., AACR 2015 #652) which is designed to undergo proteolytic cleavage upon cell uptake to release a potently cytotoxic DNA alkylator.

We show that HC-S442C mutants of human IgG1 can be conjugated via maleimide chemistry to IGN-P1 to give stable, potent, and homogeneous ADCs with drug to antibody ratio (DAR) of 2. The in vitro potency of engineered-cysteine IGN-P1 ADCs is largely dependent on the DAR of the ADC, although some difference is observed between HC-S442C and other cysteine mutants used for conjugation.

Pharmacokinetic study of C442 maleimide conjugates suggests that the chemical linkage between effector and antibody is stable upon administration in mice. Further, and in contrast to our previous observations utilizing maytansinoid ADCs, the site-specific and Lys-linked IGN-P1 ADCs showed comparable efficacy in vivo on a molar drug basis. This effect was observed across two different antibodies targeting two different cell surface antigens. These results suggest that, in certain cases, site-specific conjugation chemistry can offer comparable activity to heterogeneous conjugation at well-tolerated doses.

Citation Format: Nicholas C. Yoder, Chen Bai, Alan Wilhelm, Erin K. Maloney, Olga Ab, Emily E. Reid, Manami Shizuka, Daniel Tavares, Rassol Laleau, Xiuxia Sun, Megan E. Bogalhas, Lintao Wang, Jan Pinkas, Michael L. Miller, Ravi Chari, Thomas A. Keating. Potent in vivo activity of site-specific indolino-benzodiazepine antibody-drug conjugates (ADCs) generated via engineered cysteine conjugation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2960.

Abstract 2959: Peptide-linked indolino-benzodiazepine DNA-alkylating agents for use in antibody-drug conjugates (ADCs)

As part of our efforts to expand the available toolbox of cytotoxic payloads for use in antibody-drug conjugates (ADCs), we have recently described the development of the mono-imine-containing indolino-benzodiazepine dimer, IGN-P1 (Miller, et al., AACR 2014 #652). IGN-P1 was conjugated via a protease-cleavable peptidic L-alanine-L-alanine linker to a folate receptor α (FRα)-binding antibody, and an EGFR-binding antibody. The resulting ADCs demonstrated high in vitro potency (IC50 ∼4-100 pM) and specificity towards several cancer cell lines. In vivo, anti-FRα-IGN-P1 induced complete regressions in NCI-H2110 non-small cell lung cancer xenografts following a single dose of 3 μg/kg (linked payload dose, equivalent to 0.18 mg/kg Ab dose).

Here we describe the structure-activity relationship of a number of peptide-linked IGN ADCs, leading to the selection of Ab-IGN-P1 for further advancement. The cytotoxic activities of these peptide-IGN conjugates were evaluated in vitro in cancer cell lines with both high and low target antigen expression. We also assessed bystander activity and identified in vitro and in vivo catabolites. We found that the stereochemistry of the peptide linker was crucial for bystander activity and in vivo efficacy. The IGN-P1 ADC exhibited strong bystander activity, which we believe is dictating the strong antitumor activity in vivo. Treatment of low to moderate antigen-expressing models with Ab-IGN-P1 further resulted in tumor regressions at doses as low as 3-10 μg/kg linked payload.

These data underscore the potential therapeutic benefit of highly active and specific IGN-P1 conjugates, even for the challenging subset of patients with solid tumors where the target antigen is expressed at lower levels.

Citation Format: Manami Shizuka, Alan Wilhelm, Katie Archer, Emily Reid, Nicholas C. Yoder, Chen Bai, Nathan Fishkin, Luke Harris, Erin Maloney, Erica Hong, Rui Wu, Olga Ab, Kate Lai, Surina Sikka, Shan Jin, Jan Pinkas, Ravi Chari, Michael L. Miller. Peptide-linked indolino-benzodiazepine DNA-alkylating agents for use in antibody-drug conjugates (ADCs). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2959.

A New Class of Antibody-Drug Conjugates with Potent DNA Alkylating Activity

The promise of tumor-selective delivery of cytotoxic agents in the form of antibody-drug conjugates (ADC) has now been realized, evidenced by the approval of two ADCs, both of which incorporate highly cytotoxic tubulin-interacting agents, for cancer therapy. An ongoing challenge remains in identifying potent agents with alternative mechanisms of cell killing that can provide ADCs with high therapeutic indices and favorable tolerability. Here, we describe the development of a new class of potent DNA alkylating agents that meets these objectives. Through chemical design, we changed the mechanism of action of our novel DNA cross-linking agent to a monofunctional DNA alkylator. This modification, coupled with linker optimization, generated ADCs that were well tolerated in mice and demonstrated robust antitumor activity in multiple tumor models at doses 1.5% to 3.5% of maximally tolerated levels. These properties underscore the considerable potential of these purpose-created, unique DNA-interacting conjugates for broadening the clinical application of ADC technology. Mol Cancer Ther; 15(8); 1870-8. ©2016 AACR.

Early life history of three pelagic-spawning minnows Macrhybopsis spp. in the lower Missouri River

Life-history characteristics of age-0 sturgeon chub Macrhybopsis gelida, shoal chub Macrhybopsis hyostoma and sicklefin chub Macrhybopsis meeki were compared using several methods. All Macrhybopsis species consumed mostly midge pupae, but M. meeki had the most general diet (Levins' index, B = 0.22) compared with M. hyostoma (B = 0.02) and M. gelida (B = 0.09). Morisita's diet overlap index among species pairs ranged from 0.62 to 0.97 and was highest between M. hyostoma and M. gelida. Daily ages estimated from lapilli otoliths for each species ranged from 15 to 43 days for M. gelida, 19 to 44 for M. hyostoma and from 16 to 64 days for M. meeki. Mean growth rates ranged from 0.79 mm day(-1) for M. meeki to 1.39 mm day(-1) for M. gelida. Mortality estimates indicated high daily survivorship rates for M. meeki (0.985), but could not be estimated for the other two species. Hatch date histograms were congruent with the belief that M. hyostoma and M. gelida spawn periodically from June to September. Macrhybopsis meeki, however, appeared to respond to a specific spawning cue as hatch dates were unimodal with a peak in July. These results fill a gap in current knowledge of these imperilled species that can be used to guide management decisions.

Effects of active anti-methamphetamine vaccination on intravenous self-administration in rats

BACKGROUND

d-Methamphetamine (METH) addiction is a serious public health concern for which successful treatment remains elusive. Immunopharmacotherapy has been shown to attenuate locomotor and thermoregulatory effects of METH. The current study investigated whether active vaccination against METH could alter intravenous METH self-administration in rats.

METHODS

Male Sprague-Dawley rats (Experiment 1: N=24; Experiment 2: N=18) were vaccinated with either a control keyhole-limpet hemocyanin conjugate vaccine (KLH) or a candidate anti-METH vaccine (MH6-KLH) or. Effects of vaccination on the acquisition of METH self-administration under two dose conditions (0.05, 0.1mg/kg/inf) and post-acquisition dose-substitution (0, 0.01, 0.05, 0.20mg/kg/inf, Experiment 1; 0.01, 0.05, 0.10, 0.15mg/kg/inf, Experiment 2) during steady-state responding were investigated. Plasma METH concentrations were determined 30min after an acute challenge dose of 3.2mg/kg METH.

RESULTS

Active vaccination inhibited the acquisition of METH self-administration under the 0.1mg/kg/inf dose condition, with 66% of the MH6-KLH-vaccinated rats compared to 100% of the controls reaching criteria, and produced transient and dose-dependent effects on self-administration during the maintenance phase. Under the 0.05mg/kg/inf dose condition, MH6-KLH-vaccinated rats initially self-administered more METH than controls, but then self-administration decreased across the acquisition phase relative to controls; a subsequent dose-response assessment confirmed that MH6-KLH-vaccinated rats failed to acquire METH self-administration. Finally, plasma METH concentrations were higher in MH6-KLH-vaccinated rats compared to controls after an acute METH challenge, and these were positively correlated with antibody titers.

CONCLUSIONS

These data demonstrate that active immunopharmacotherapy for METH attenuates the acquisition of METH self-administration.

Abstract 652: Antibody-drug conjugates (ADCs) of indolino-benzodiazepine DNA-alkylating agents

There are over thirty ADCs in the clinic today, reflecting the interest in ADCs for the treatment of cancer. Most of these ADCs utilize a tubulin-interacting small molecule as their cytotoxic payload. In order to continue to extend the utility of ADCs to more types of cancers, there is a strong interest in developing cytotoxic payloads with other mechanisms of action. Previously we have described the development of a class of indolino-benzodiazepine dimers (IGNs) with high potency and specificity. ADCs made with a mono-imine containing IGN, which only alkylate DNA, were found to display improved tolerability, along with the absence of delayed toxicity, compared to their DNA-cross-linking di-imine counterparts.

Additional structure-activity relationship studies with mono-imine containing IGNs have resulted in two promising new leads, IGN-D1 and IGN-P1, which are conjugated to an antibody via either a disulfide or peptide linker, respectively. ADCs of IGN-D1 and IGN-P1 were prepared for evaluation using a folate receptor α (FRα)-binding antibody, anti-FRα, and EGFR-binding antibody, anti-EGFR.

Anti-FRα-IGN-D1 and anti-FRα-IGN-P1 were found to be highly potent against the FRα-expressing KB cell line (IC50 values of 8 pM and 4 pM, respectively) and also demonstrated strong activity against nearby target-negative cancer cells. The addition of excess unconjugated antibody blocked the cytotoxic effect of these conjugates, thus demonstrating that their activity is antigen specific. In addition, both anti-FRα-IGN conjugates were found to be highly potent (IC50 values of 100 pM and 30 pM, respectively) against the breast ductal carcinoma cell line, T47D, despite only a moderate level of antigen expression on the target cells. Similarly, anti-EGFR-IGN-D1 and anti-EGFR-IGN-P1 were found to have IC50 values in the picomolar range against a panel of EGFR-expressing cell lines. In vivo, anti-FRα-IGN-D1 and anti-FRα-IGN-P1 were found to be effective against NCI-H2110 non-small cell lung cancer xenografts, with anti-tumor activity observed at single doses as low as 3 μg/kg (payload dose, equivalent to 0.15 mg/kg Ab dose).

These data support evaluation of new ADC therapies with these two new IGNs for solid tumor indications as well as tumors with low antigen expression.

Citation Format: Michael L. Miller, Manami Shizuka, Nathan Fishkin, Emily Reid, Katie Archer, Erin Maloney, Chen Bai, Olga Ab, Nick C. Yoder, Rui Wu, Erica Hong, Megan Bogalhas, Alan Wilhelm, Kathleen Whiteman, Ravi Chari. Antibody-drug conjugates (ADCs) of indolino-benzodiazepine DNA-alkylating agents. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 652. doi:10.1158/1538-7445.AM2015-652

Abstract B98: Final results of a randomized phase Ib study of fractionated 90Y-clivatuzumab tetraxetan in patients with metastatic pancreatic cancer having at least two prior therapies

Background: Prior clinical studies in the first and second line setting showed radioimmunotherapy (RAIT) is a promising therapy for pancreatic cancer that avoids the side effects of further chemotherapy. This multicenter study evaluated the contribution of low radiosensitizing doses of gemcitabine (GEM) to fractionated doses of 90Y-clivatuzumab tetraxetan in patients with metastatic pancreatic ductal cancer after having received at least 2 prior systemic therapies.

Methods: Fifty-eight patients (33 males, 25 females; median age 63.5 years), 1.6 median years from diagnosis and with a median of 3 (2-7) prior treatments, were randomized to Arm A (N=29, 4-week cycles: 200 mg/m2 GEM, weekly, combined with 6.5 mCi/m2 90Y-clivatuzumab tetraxetan, weekly the last 3 weeks) or Arm B (N=29, 3-week cycles: 6.5 mCi/m2 90Y-clivatuzumab tetraxetan alone, once-weekly), repeating cycles after 4-week delays. Safety and efficacy were evaluated.

Results: None of the patients had infusion reactions, and as expected, cytopenias (predominantly thrombocytopenia) were the only significant toxicities, but mostly transient and manageable with infrequent hematologic support and little evidence of increased infection or bleeding. Patients terminated treatment cycles due to disease progression or clinical deterioration, not treatment toxicity. Fifty-three patients (27 Arm A, 26 Arm B, 91% overall) completed ≥1 full treatment cycle and thus were evaluable for efficacy, with 23 (12 Arm A, 11 Arm B; 40%) receiving multiple cycles, including 7 (6 Arm A, 1 Arm B; 12%) given 3-7 cycles. Two patients in Arm A had PRs by RECIST criteria. Karnofsky performance status (90-100 v 70-80), number of prior therapies, and tumor burden estimates (summed length of index lesions, serum CA 19-9 levels) correlated with overall survival (OS), but appear balanced between arms. Kaplan-Meier median OS was 3.9 months (1.0-16.7) in Arm A v 2.8 months (0.9-9.4) in Arm B (hazard ratio 0.54, 95% CI: 0.27-0.87; P=0.020, log-rank). The median OS for Arm A v Arm B increased to 7.9 v 3.4 months with multiple cycles (P= 0.004) and 3 patients in Arm A still being observed (11 – 17 months).

Conclusions: This randomized trial demonstrated the feasibility of performing clinical studies in metastatic pancreatic cancer patients after having at least 2 prior therapies (3rd line and beyond). With significant survival advantage and favorable safety profile, fractionated RAIT with 90Y-clivatuzumab tetraxetan and low-dose GEM appears promising in this difficult population, supporting Phase 3 studies of this combination now being initiated.

Citation Format: Vincent J. Picozzi, Ramesh K. Ramanathan, Maeve A. Lowery, Allyson J. Ocean, Edith P. Mitchell, Bert H. O'Neil, Michael J. Guarino, Paul R. Conkling, Steven J. Cohen, Nathan Bahary, Richard C. Frank, Tomislav Dragovich, Benjamin B. Bridges, Marie Lee, Ronald L. Korn, Neeta Pandit-Taskar, Stanley J. Goldsmith, Charles M. Intenzo, Arif Sheikh, Timothy C. Manzone, Michael L. Miller, Michael Yu, Judith M. Joyce, Edward B. Strauss, Susan Passalaqua, Ronald V. Dorn, III, Michael J. Anderson, Michael Holt, Fadi S. Braiteh, Fa-Chyi Lee, Thomas E. Gribbin, Donald A. Richards, Alexander N. Starodub, Wegener A. William, Eileen M. O'Reilly, Daniel D. Von Hoff, David M. Goldenberg. Final results of a randomized phase Ib study of fractionated 90Y-clivatuzumab tetraxetan in patients with metastatic pancreatic cancer having at least two prior therapies. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr B98.

Single-Electron Detection and Spectroscopy via Relativistic Cyclotron Radiation

It has been understood since 1897 that accelerating charges must emit electromagnetic radiation. Although first derived in 1904, cyclotron radiation from a single electron orbiting in a magnetic field has never been observed directly. We demonstrate single-electron detection in a novel radio-frequency spectrometer. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta electron spectroscopy from gaseous radiation sources is a key technique in modern efforts to measure the neutrino mass via the tritium decay end point, and this work demonstrates a fundamentally new approach to precision beta spectroscopy for future neutrino mass experiments.

The natural history of pediatric-onset discoid lupus erythematosus

BACKGROUND

Pediatric discoid lupus erythematosus (DLE) is rare. The risk of progression to systemic lupus erythematosus (SLE) is uncertain.

OBJECTIVE

We sought to determine the risk of progression of pediatric DLE to SLE and to characterize its phenotype.

METHODS

This was a retrospective review of 40 patients with DLE.

RESULTS

Six (15%) of 40 patients presented with DLE as a manifestation of concurrent SLE. Of the remaining 34, 9 (26%) eventually met SLE criteria and 15 (44%) developed laboratory abnormalities without meeting SLE criteria. Only 10 (29%) maintained skin-limited disease. The average age at progression to SLE was 11 years, with greatest risk in the first year after DLE diagnosis. Most (89%) patients with SLE met diagnostic criteria with mucocutaneous disease (discoid lesions, malar rash, oral and nasal ulcers, photosensitivity), positive antibodies, and/or cytopenia without developing end-organ damage over 5 years of median follow-up.

LIMITATIONS

The study was retrospective.

CONCLUSIONS

In pediatric patients, DLE carries a significant risk of progression to SLE but may predict a milder phenotype of systemic disease. All patients require careful monitoring for SLE, particularly within the first year of diagnosis.

Randomized, double-blind, placebo-controlled trial of the efficacy and safety of rilonacept in the treatment of systemic juvenile idiopathic arthritis

OBJECTIVE

To assess the efficacy and safety of rilonacept, an interleukin-1 inhibitor, in a randomized, double-blind, placebo-controlled trial.

METHODS

An initial 4-week double-blind placebo phase was incorporated into a 24-week randomized multicenter design, followed by an open-label phase. Seventy-one children who had active arthritis in ≥2 joints were randomized (1:1) to the 2 arms of the study. Patients in the rilonacept arm received rilonacept (loading dose 4.4 mg/kg followed by 2.2 mg/kg weekly, subcutaneously) beginning on day 0. Patients in the placebo arm received placebo for 4 weeks followed by a loading dose of rilonacept at week 4 followed by weekly maintenance doses. The primary end point was time to response, using the adapted American College of Rheumatology Pediatric 30 criteria coupled with the absence of fever and taper of the dosage of systemic corticosteroids, using prespecified criteria.

RESULTS

The time to response was shorter in the rilonacept arm than in the placebo arm (χ(2) = 7.235, P = 0.007). The secondary analysis, which used the same response criteria, showed that 20 (57%) of 35 patients in the rilonacept arm had a response at week 4 compared with 9 (27%) of 33 patients in the placebo arm (P = 0.016). Exacerbation of systemic juvenile idiopathic arthritis (JIA) was the most common severe adverse event. More patients in the rilonacept arm had elevated liver transaminase levels (including levels more than 3 times the upper limit of normal) compared with those in the placebo arm. Adverse events were similar in the 2 arms of the study.

CONCLUSION

Rilonacept was generally well tolerated and demonstrated efficacy in active systemic JIA.

Parental THC exposure leads to compulsive heroin-seeking and altered striatal synaptic plasticity in the subsequent generation

Recent attention has been focused on the long-term impact of cannabis exposure, for which experimental animal studies have validated causal relationships between neurobiological and behavioral alterations during the individual's lifetime. Here, we show that adolescent exposure to Δ(9)-tetrahydrocannabinol (THC), the main psychoactive component of cannabis, results in behavioral and neurobiological abnormalities in the subsequent generation of rats as a consequence of parental germline exposure to the drug. Adult F1 offspring that were themselves unexposed to THC displayed increased work effort to self-administer heroin, with enhanced stereotyped behaviors during the period of acute heroin withdrawal. On the molecular level, parental THC exposure was associated with changes in the mRNA expression of cannabinoid, dopamine, and glutamatergic receptor genes in the striatum, a key component of the neuronal circuitry mediating compulsive behaviors and reward sensitivity. Specifically, decreased mRNA and protein levels, as well as NMDA receptor binding were observed in the dorsal striatum of adult offspring as a consequence of germline THC exposure. Electrophysiologically, plasticity was altered at excitatory synapses of the striatal circuitry that is known to mediate compulsive and goal-directed behaviors. These findings demonstrate that parental history of germline THC exposure affects the molecular characteristics of the striatum, can impact offspring phenotype, and could possibly confer enhanced risk for psychiatric disorders in the subsequent generation.