SBIR-STTR Award

Autism Spectrum Disorder (ASD) describes a collection of neurodevelopmental abnormalities of varying severity that have been estimated to impact more than 1% of Americans, mostly males. ASD can negatively impact one’s ability to communicate and navigate social interactions. In its most severe forms, ASD also can lead to self-­destructive, repetitive behaviors that require afflicted persons be institutionalized for their own safety. The prevalence of ASD has grown in recent decades;; one explanation for this trend is that poorly appreciated environmental factors have raised the underlying incidence of the disorder. Early in utero exposure to circulating maternal antibodies (Ab) has been implicated increasingly as a major risk factor for children to develop ASD. This model posits that maternal antibodies bind to proteins on the surface of the fetal brain and interfere with normal development. It is supported by studies in mice and monkeys that have revealed that sera purified from mothers with ASD children, when injected before a critical point in gestation, can trigger changes in brain anatomy and ASD-­like behavioral phenotypes in offspring. Indeed, > 10% of ASD cases may be explained by fetal exposure to maternal brain-­reactive antibodies. Yet this mode of pathogenesis has two salient consequences: 1) maternal Ab represent detectable biomarkers that can indicate ASD risk, and 2) ASD risk could be mitigated by treating mothers with a “decoy antigen” to neutralize deleterious antibodies. Spark2Flame (S2F) seeks to develop clinical products in both of these areas. S2F’s efforts to identify ASD-­risk biomarkers led to the isolation of a monoclonal antibody, C6, that recognizes the transmembrane protein Caspr2, which has been associated with ASD through pedigree analysis. Injecting pregnant mice with purified C6 causes defects in brain anatomy and behavioral phenotypes in male offspring, recapitulating the sex-­bias ASD shows in humans. Two additional Ab, cloned from other mothers, also bind Caspr2. These results argue that Caspr2-­reactive antibodies are predisposing for ASD. In this Phase I SBIR, S2F will examine the feasibility of developing a predictive clinical diagnostic assay for ASD-­risk based on detecting maternal serum reactivity to Caspr2. In Aim 1, mice will be immunized with Caspr2 before pregnancy to test the pathogenicity of pre-­existing, polyclonal Caspr2 antibodies for disrupting normal brain development. In Aim 2, S2F will develop a proof-­of-­concept ELISA method for rapidly and inexpensively detecting Caspr2 reactivity in serum. Finally, to discover predictive biomarkers for ASD risk, serum Caspr2-­epitope binding profiles will be compared between mothers of a normally developing child and mothers of an ASD child (Aim 3). Successful completion of this Phase I project will identify the most deleterious Caspr2-­reactive maternal antibodies, which will focus efforts to develop a predictive clinical diagnostic assay and inform strategies to create a biologic therapeutic to neutralize these antibodies.

Public Health Relevance Statement:
Project Narrative In utero exposure to brain-­reactive antibodies is a significant risk factor for developing Autism Spectrum Disorder (ASD), a collection of neurodevelopmental disorders that can have impair an individual’s ability to communicate and function independently. Spark2Flame has developed an innovative strategy to identify pathogenic antibodies. Spark2Flame is seeking to advance a diagnostic test to gauge ASD risk that incorporates these biomarkers and to develop matched therapeutic biologics to neutralize these antibodies.

Project Terms:
1 year old; Affect; American; Anatomy; Antibodies; Antigens; Area; autism spectrum disorder; Autoantibodies; Autoimmunity; Awareness; base; Behavioral; Binding; Biological Assay; Biological Markers; Brain; Child; Chimeric Proteins; Clinical; clinical diagnostics; clinical predictors; Collaborations; Collection; Communication; Companions; Consensus; critical period; Data Set; Defect; design; Detection; Development; Diagnosis; Diagnostic; diagnostic assay; Diagnostic tests; Diamond; Disease; disorder risk; Early Intervention; Employment; Environmental Risk Factor; Enzyme-Linked Immunosorbent Assay; Epitopes; Exhibits; experimental study; Exposure to; Extracellular Domain; Female; fetal; Foundations; Future; Genes; genetic pedigree; Genetic study; Goals; Histologic; Human; Human Genetics; Immunize; Impairment; improved; Incidence; Individual; Injectable; innovation; Institutes; Institutionalization; Integral Membrane Protein; Knowledge; Laboratories; Lead; male; Maternal antibody; maternal serum; Medical Research; Modeling; Monkeys; Monoclonal Antibodies; Mothers; Mus; Mutation; Neurodevelopmental Disorder; Neurologic; neutralizing antibody; offspring; Outcome; Partner in relationship; Pathogenesis; Pathogenicity; Patients; Persons; Phage Display; Phase; Phenotype; predictive marker; Pregnancy; pregnant; prenatal exposure; Prevalence; prevent; prospective; Proteins; rapid technique; Reaction; repetitive behavior; Research; Risk; Risk Factors; Safety; Sampling; Self-Injurious Behavior; Serum; Severities; Sex Bias; Small Business Innovation Research Grant; Social Interaction; Surface; Symptoms; Testing; Therapeutic; Time; trend; Work

Autism Spectrum Disorder (ASD) describes a collection of neurodevelopmental abnormalities of varying severity that have been estimated to impact more than 1% of Americans, mostly males. ASD can negatively impact one?s ability to communicate and navigate social interactions. In its most severe forms, ASD also can lead to self-destructive, repetitive behaviors that require afflicted persons be institutionalized for their own safety. The prevalence of ASD has grown in recent decades; one explanation for this trend is that poorly appreciated environmental factors have raised the underlying incidence of the disorder. Early in utero exposure to circulating maternal antibodies (Ab) has been implicated increasingly as a major risk factor for children to develop ASD. This model posits that maternal antibodies bind to proteins on the surface of the fetal brain and interfere with normal development. It is supported by studies in mice and monkeys that have revealed that sera purified from mothers with ASD children, when injected before a critical point in gestation, can trigger changes in brain anatomy and ASD-like behavioral phenotypes in offspring. Indeed, > 10% of ASD cases may be explained by fetal exposure to maternal brain-reactive antibodies. Yet this mode of pathogenesis has two salient consequences: 1) maternal Ab represent detectable biomarkers that can indicate ASD risk, and 2) ASD risk could be mitigated by treating mothers with a ?decoy antigen? to neutralize deleterious antibodies. Spark2Flame (S2F) seeks to develop clinical products in both of these areas. During Phase I work, S2F showed in mice that prenatal exposure to antibodies that bind the transmembrane protein Caspr2 disrupts brain development and causes behavioral phenotypes in male offspring. This effect, which recapitulates the sex-bias ASD shows in humans, was corroborated in several distinct mouse models. Thus, these results strongly recommend Caspr2-reactive antibodies as targets for a ?decoy antigen? therapy. In this Phase II SBIR, S2F will test a panel of therapeutic biologics based on the Caspr2 extracellular domain fused to IgG Fc domain to increase stability. In Aim 1, candidates will be characterized stability and for ability to neutralize Caspr2-reactive antibodies, and the panel will be narrowed to two lead candidates (leads). Aims 2 and 3 conduct preliminary toxicology studies in adult and fetal mice, respectively. In Aim 4, S2F explores the immunotoxicity of leads in mice with humanized immune systems. Aim 5 tests the efficacy of leads for blocking the pathogenic effects of polyclonal maternal Caspr2 immunity by assaying the brain morphology and behavioral phenotypes of offspring. Successful completion of this Phase II project will establish a strong foundation for continued pre-clinical development of leads, which ultimately may result in a first-in-class therapy to mitigate ASD risk caused by a class of pathologic maternal antibodies.

Thesaurus Terms:
1 Year Old; Address; Adult; Affect; American; Anatomy; Animal Model; Antibodies; Antigen-Antibody Complex; Antigens; Area; Autism Spectrum Disorder; Autoantibodies; Autoimmunity; Awareness; Base; Behavioral; Binding; Biological Assay; Biological Markers; Biological Response Modifier Therapy; Blood; Blood Circulation; Brain; Brain Morphology; Child; Clinical; Collaborations; Collection; Communication; Consensus; Deposition; Design; Detection; Development; Diagnosis; Diamond; Disease; Disorder Risk; Dose; Drug Kinetics; Early Intervention; Efficacy Testing; Employment; Environmental Risk Factor; Exhibits; Exposure To; Extracellular Domain; Fc Domain; Female; Fetal; Foundations; Future; Genes; Genetic Study; Goals; Half-Life; Human; Human Genetics; Humanized Mouse; Immune System; Immunity; Immunoglobulin G; Immunotoxicity; Impairment; Improved; In Utero; In Vitro; In Vivo; Incidence; Individual; Institutes; Institutionalization; Integral Membrane Protein; Knowledge; Laboratories; Lead; Lead Candidate; Link; Male; Maternal Antibody; Measures; Medical Research; Modeling; Monkeys; Monoclonal Antibodies; Mothers; Mouse Model; Mus; Mutation; Neurodevelopmental Disorder; Neurologic; Neutralizing Antibody; Offspring; Outcome; Pathogenesis; Pathogenicity; Pathologic; Patients; Persons; Phase; Phenotype; Pre-Clinical; Preclinical Development; Pregnancy; Pregnant; Prenatal; Prenatal Exposure; Prevalence; Prevent; Preventive; Prospective; Proteins; Repetitive Behavior; Research; Risk; Risk Factors; Safety; Self-Injurious Behavior; Serum; Severities; Sex Bias; Small Business Innovation Research Grant; Social Interaction; Spontaneous Abortion; Stem; Surface; Symptoms; Testing; Therapeutic; Therapeutic Candidate; Time; Tissues; Toxic Effect; Toxicology; Trend; Work;