Long-read sequencing and optical genome mapping identify causative gene disruptions in noncoding sequence in two patients with neurologic disease and known chromosome abnormalities.

Despite advances in next generation sequencing (NGS), genetic diagnoses remain elusive for many patients with neurologic syndromes. Long-read sequencing (LRS) and optical genome mapping (OGM) technologies improve upon existing capabilities in the detection and interpretation of structural variation in repetitive DNA, on a single haplotype, while also providing enhanced breakpoint resolution. We performed LRS and OGM on two patients with known chromosomal rearrangements and inconclusive Sanger or NGS. The first patient, who had epilepsy and developmental delay, had a complex translocation between two chromosomes that included insertion and inversion events. The second patient, who had a movement disorder, had an inversion on a single chromosome disrupted by multiple smaller inversions and insertions. Sequence level resolution of the rearrangements identified pathogenic breaks in noncoding sequence in or near known disease-causing genes with relevant neurologic phenotypes (MBD5, NKX2-1). These specific variants have not been reported previously, but expected molecular consequences are consistent with previously reported cases. As the use of LRS and OGM technologies for clinical testing increases and data analyses become more standardized, these methods along with multiomic data to validate noncoding variation effects will improve diagnostic yield and increase the proportion of probands with detectable pathogenic variants for known genes implicated in neurogenetic disease.

Multisite Evaluation and Validation of Optical Genome Mapping for Prenatal Genetic Testing.

Prenatal diagnostic testing of amniotic fluid, chorionic villi, or more rarely, fetal cord blood is recommended following a positive or unreportable noninvasive cell-free fetal DNA test, abnormal maternal biochemical serum screen, abnormal ultrasound, or increased genetic risk for a cytogenomic abnormality based on family history. Although chromosomal microarray is recommended as the first-tier prenatal diagnostic test, in practice, multiple assays are often assessed in concert to achieve a final diagnostic result. The use of multiple methodologies is costly, time consuming, and labor intensive. Optical genome mapping (OGM) is an emerging technique with application for prenatal diagnosis because of its ability to detect and resolve, in a single assay, all classes of pathogenic cytogenomic aberrations. In an effort to characterize the potential of OGM as a novel alternative to traditional standard of care (SOC) testing of prenatal samples, OGM was performed on a total of 200 samples representing 123 unique cases, which were previously tested with SOC methods (92/123 = 74.7% cases tested with at least two SOCs). OGM demonstrated an overall accuracy of 99.6% when compared with SOC methods, a positive predictive value of 100%, and 100% reproducibility between sites, operators, and instruments. The standardized workflow, cost-effectiveness, and high-resolution cytogenomic analysis demonstrate the potential of OGM to serve as a first-tier test for prenatal diagnosis.

14q22.3 duplication including OTX2 in a girl with medulloblastoma: A case report with literature review.

Orthodenticle homeobox 2 (OTX2) is a known oncogenic driver of medulloblastoma. Germline duplication of 14q22.3 including OTX2 is a rare condition reported in patients with combined pituitary hormone deficiency, oculo-auriculo-vertebral spectrum, and hemifacial microsomia. There has been one previously published case of a patient carrying a 14q22.3 duplication that included OTX2 with hemifacial microsomia who also developed medulloblastoma. Here, we present a case of a 6-year-old girl with a history of delayed development who was diagnosed with medulloblastoma. Genetic evaluations revealed that she inherited a germline duplication of 14q22.3, which included OTX2. This genetic alteration was passed down from her mother, who also had a history of delayed development. Results from other genetic testing, including exome sequencing, fragile X syndrome, and mtDNA testing, were negative/normal. This is the second report of a 14q22.3 duplication that included OTX2 in a patient with medulloblastoma. Further studies are necessary to establish a clear association.

Identification of Biallelic dystrophin gene variants during maternal carrier testing for Becker muscular dystrophy and review of the DMD exon 49-51 deletion phenotype.

BACKGROUND: Dystrophinopathies are X-linked recessive conditions caused by pathogenic variants in the dystrophin (DMD) gene. In a family that included two boys with Becker muscular dystrophy (BMD) due to a DMD deletion of exons 45-47, maternal carrier testing unexpectedly identified biallelic DMD deletions of exons 45-47 and 49-51. METHODS: The patient's mild phenotype in the setting of biallelic DMD variants prompted further investigation of the exon 49-51 deletion in particular, via literature review and retrospective chart review of patients who have been evaluated in our institution's comprehensive neuromuscular center and/or diagnosed in our clinical genetic testing laboratory. RESULTS: To our knowledge, this is only the fifth case of confirmed biallelic DMD variants in a female. In males, the DMD exon 49-51 deletion appears to result in a mild BMD phenotype with low or normal creatine kinase levels. This deletion comprised 19% (4/21) of dystrophinopathies diagnosed by chromosomal microarray (CMA) in males during the past ten years in our clinical laboratory. Most individuals identified by chart review were diagnosed through CMA, despite the fact that microarray was genome-wide and not DMD-specific. This case raised important genetic counseling issues. CONCLUSION: The DMD exon 49-51 deletion appears to cause a variable but generally mild BMD phenotype. Its relatively frequent detection by CMA suggests it may be underdiagnosed.

Further expansion and confirmation of phenotype in rare loss of YWHAE gene distinct from Miller-Dieker syndrome.

Deletion of 17p13.3 has varying degrees of severity on brain development based on precise location and size of the deletion. The most severe phenotype is Miller-Dieker syndrome (MDS) which is characterized by lissencephaly, dysmorphic facial features, growth failure, developmental disability, and often early death. Haploinsufficiency of PAFAH1B1 is responsible for the characteristic lissencephaly in MDS. The precise role of YWHAE haploinsufficiency in MDS is unclear. Case reports are beginning to elucidate the phenotypes of individuals with 17p13.3 deletions that have deletion of YWHAE but do not include deletion of PAFAH1B1. Through our clinical genetics practice, we identified four individuals with 17p13.3 deletion that include YWHAE but not PAFAH1B1. These patients have a similar phenotype of dysmorphic facial features, developmental delay, and leukoencephalopathy. In a review of the literature, we identified 19 patients with 17p13.3 microdeletion sparing PAFAH1B1 but deleting YWHAE. Haploinsufficiency of YWHAE is associated with brain abnormalities including cystic changes. These individuals have high frequency of epilepsy, intellectual disability, and dysmorphic facial features including prominent forehead, epicanthal folds, and broad nasal root. We conclude that deletion of 17p13.3 excluding PAFAH1B1 but including YWHAE is associated with a consistent phenotype and should be considered a distinct condition from MDS.

Characterization of a rare mosaic unbalanced translocation of t(3;12) in a patient with neurodevelopmental disorders.

BACKGROUND: Unbalanced translocations may be de novo or inherited from one parent carrying the balanced form and are usually present in all cells. Mosaic unbalanced translocations are extremely rare with a highly variable phenotype depending on the tissue distribution and level of mosaicism. Mosaicism for structural chromosomal abnormalities is clinically challenging for diagnosis and counseling due to the limitation of technical platforms and complex mechanisms, respectively. Here we report a case with a tremendously rare maternally-derived mosaic unbalanced translocation of t(3;12), and we illustrate the unreported complicated mechanism using single nucleotide polymorphism (SNP) array, fluorescence in situ hybridization (FISH), and chromosome analyses. CASE PRESENTATION: An 18-year-old female with a history of microcephaly, pervasive developmental disorder, intellectual disability, sensory integration disorder, gastroparesis, and hypotonia presented to our genetics clinic. She had negative karyotype by parental report but no other genetic testing performed previously. SNP microarray analysis revealed a complex genotype including 8.4 Mb terminal mosaic duplication on chromosome 3 (3p26.3->3p26.1) with the distal 5.7 Mb involving two parental haplotypes and the proximal 2.7 Mb involving three parental haplotypes, and a 6.1 Mb terminal mosaic deletion on chromosome 12 (12p13.33->12p13.31) with no evidence for a second haplotype. Adjacent to the mosaic deletion is an interstitial mosaic copy-neutral region of homozygosity (1.9 Mb, 12p13.31). The mother of this individual was confirmed by chromosome analysis and FISH that she carries a balanced translocation, t(3;12)(p26.1;p13.31). CONCLUSION: Taken together, the proband, when at the stage of a zygote, likely carried the derivative chromosome 12 from this translocation, and a postzygotic mitotic recombination event occurred between the normal paternal chromosome 12 and maternal derivative chromosome 12 to "correct" the partial 3p trisomy and partial deletion of 12p. To the best of our knowledge, it is the first time to report the mechanism utilizing a combined cytogenetic and cytogenomic approach, and we believe it expands our knowledge of mosaic structural chromosomal disorders and provides new insight into clinical management and genetic counseling.

Genetic Testing in Patients with Neurodevelopmental Disorders: Experience of 511 Patients at Cincinnati Children's Hospital Medical Center.

Our institution developed and continuously improved a Neurodevelopmental Reflex (NDR) algorithm to help physicians with genetic test ordering for neurodevelopmental disorders (NDDs). To assess its performance, we performed a retrospective study of 511 patients tested through NDR from 2018 to 2019. SNP Microarray identified pathogenic/likely pathogenic copy number variations in 27/511 cases (5.28%). Among the 484 patients tested for Fragile X FMR1 CGG repeats, a diagnosis (0.20%) was established for one male mosaic for a full mutation, a premutation, and a one-CGG allele. Within the 101 normocephalic female patients tested for MECP2, two patients were found to carry pathogenic variants (1.98%). This retrospective study suggested the NDR algorithm effectively established diagnoses for patients with NDDs with a yield of 5.87%.

Aneuploid embryo transfer: clinical policies and provider opinions at United States fertility clinics.

OBJECTIVE: To describe institutional clinical policies and individual provider opinions regarding aneuploid embryo transfer (aET). DESIGN: A survey about clinical policies was electronically sent to Society for Assisted Reproductive Technology (SART) member laboratory directors, and a separate survey about personal opinions was electronically sent to all SART members. SETTING: Not applicable. PATIENTS: Patients pursuing preimplantation genetic testing for aneuploidy (PGT-A). INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: Current clinical policies about aET were described. Individual provider opinions about aET in the context of specific aneuploidies and mosaicism were also described. RESULTS: A total of 48 laboratory directors and 212 individual providers responded to their respective surveys. Twelve (25%) clinics report that they do not have a policy regarding aET, but clinics performing PGT-A in >100 cycles per year were more likely to have a policy. Half of the individual providers agree that an embryo with trisomy 21 should be available for aET, but most disagreed with aET of embryos with other aneuploidies and most were either unsure about or unwilling to transfer embryos with mosaicism. Those who worked in primarily patient-facing roles held more agreeable opinions regarding aET. CONCLUSION: There is no consensus regarding ideal clinical policies for aET. The wide range of current clinical practices and individual provider opinions regarding under what circumstances, if any, aET should be available to patients indicates that this is a divisive issue among ART providers, and there is a clear need for specific professional guidelines to address this issue.

Confirmatory testing illustrates additional risks for structural sex chromosome abnormalities in fetuses with a non-invasive prenatal screen positive for monosomy X.

More and more women rely on non-invasive prenatal screening (NIPS) to detect fetal sex and risk for aneuploidy. The testing applies massively parallel sequencing or single nucleotide polymorphism (SNP) microarray to circulating cell-free DNA to determine relative copy number. In addition to trisomies 13, 18, and 21, some labs offer screening for sex chromosome abnormalities as part of their test. In this study, an index neonate screened positive for monosomy X and had discordant postnatal chromosomes indicating an X;autosome translocation. This patient prompted a retrospective chart review for similar cases at a large NIPS testing center. The review found 28 patients with an abnormal NIPS for monosomy X who were eventually diagnosed with additional discrepant structural sex chromosome abnormalities including translocations, isochromosomes, deletions, rings, markers, and uniparental disomy. The majority of these were mosaic with monosomy X, but in seven cases, there was no evidence of mosaicism on confirmatory testing. The identification of multiple sex chromosome aneuploidies in these cases supports the need for additional genetic counseling prior to NIPS testing and following abnormal NIPS results that are positive for monosomy X. This finding broadens our knowledge about the variable outcomes of positive monosomy X NIPS results and emphasizes the importance of confirmatory testing and clinical follow up for these patients.

Evidence-based review of genomic aberrations in B-lymphoblastic leukemia/lymphoma: Report from the cancer genomics consortium working group for lymphoblastic leukemia.

Clinical management and risk stratification of B-lymphoblastic leukemia/ lymphoma (B-ALL/LBL) depend largely on identification of chromosomal abnormalities obtained using conventional cytogenetics and Fluorescence In Situ Hybridization (FISH) testing. In the last few decades, testing algorithms have been implemented to support an optimal risk-oriented therapy, leading to a large improvement in overall survival. In addition, large scale genomic studies have identified multiple aberrations of prognostic significance that are not routinely tested by existing modalities. However, as chromosomal microarray analysis (CMA) and next-generation sequencing (NGS) technologies are increasingly used in clinical management of hematologic malignancies, these abnormalities may be more readily detected. In this article, we have compiled a comprehensive, evidence-based review of the current B-ALL literature, focusing on known and published subtypes described to date. More specifically, we describe the role of various testing modalities in the diagnosis, prognosis, and therapeutic relevance. In addition, we propose a testing algorithm aimed at assisting laboratories in the most effective detection of the underlying genomic abnormalities.

Algorithm-Driven Electronic Health Record Notification Enhances the Detection of Turner Syndrome.

Early diagnosis of Turner syndrome enhances care, but in routine practice, even within larger referral centers, diagnosis is delayed. Our study examines the utility of an electronic health record algorithm in identifying patients at high risk for Turner syndrome. Six percent of those identified had missed diagnoses of Turner syndrome.

Neonatal Lung Disease Associated with TBX4 Mutations.

Variable lung disease was documented in 2 infants with heterozygous TBX4 mutations; their clinical presentations, pathology, and outcomes were distinct. These findings demonstrate that TBX4 gene mutations are associated with neonatal respiratory failure and highlight the wide spectrum of clinicopathological outcomes that have implications for patient diagnosis and management.

Analysis of copy number variants in 11 pairs of monozygotic twins with neurofibromatosis type 1.

Phenotypic variability among individuals with neurofibromatosis type 1 (NF1) has long been a challenge for clinicians and an enigma for researchers. Members of the same family and even identical twins with NF1 often demonstrate variable disease expression. Many mechanisms for this variability have been proposed. We have performed an exploratory study of copy number variants (CNVs) as a possible source of phenotypic variability in NF1. We enrolled 11 pairs of monozygotic (MZ) twins with NF1 and their parents, catalogued their clinical characteristics, and utilized a single nucleotide polymorphism (SNP) microarray to identify CNVs in blood and saliva. The 11 twin pairs showed high concordance for presence and number of café-au-lait spots, cutaneous neurofibromas, IQ, and ADHD. They were more likely to be discordant for optic pathway glioma, plexiform neurofibromas, skeletal manifestations, and malignancy. Microarray analysis identified a total of 81 CNVs meeting our conservative criteria, 37 of which overlap known genes. Of interest, three CNVs were previously unreported. Microarray analysis failed to ascertain any CNV differences within twin pairs, between twins and parents, or between tissues in any one individual. Results of this small pilot study did not demonstrate any de novo CNV events in our MZ twin pairs, nor were de novo CNVs overrepresented in these individuals with NF1. A much larger sample size would be needed to form any conclusions about the role of CNVs in NF1 variable expressivity. Alternative explanations for discordant phenotypes include epigenetic changes, smaller genetic alterations, or environmental factors. © 2016 Wiley Periodicals, Inc.

Copy number variation as a genetic basis for heterotaxy and heterotaxy-spectrum congenital heart defects.

Genomic disorders and rare copy number abnormalities are identified in 15-25% of patients with syndromic conditions, but their prevalence in individuals with isolated birth defects is less clear. A spectrum of congenital heart defects (CHDs) is seen in heterotaxy, a highly heritable and genetically heterogeneous multiple congenital anomaly syndrome resulting from failure to properly establish left-right (L-R) organ asymmetry during early embryonic development. To identify novel genetic causes of heterotaxy, we analysed copy number variants (CNVs) in 225 patients with heterotaxy and heterotaxy-spectrum CHDs using array-based genotyping methods. Clinically relevant CNVs were identified in approximately 20% of patients and encompassed both known and putative heterotaxy genes. Patients were carefully phenotyped, revealing a significant association of abdominal situs inversus with pathogenic or likely pathogenic CNVs, while d-transposition of the great arteries was more frequently associated with common CNVs. Identified cytogenetic abnormalities ranged from large unbalanced translocations to smaller, kilobase-scale CNVs, including a rare, single exon deletion in ZIC3, a gene known to cause X-linked heterotaxy. Morpholino loss-of-function experiments in Xenopus support a role for one of these novel candidates, the platelet isoform of phosphofructokinase-1 (PFKP) in heterotaxy. Collectively, our results confirm a high CNV yield for array-based testing in patients with heterotaxy, and support use of CNV analysis for identification of novel biological processes relevant to human laterality.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.

Nonclinical Evaluation of PF-06438179: A Potential Biosimilar to Remicade® (Infliximab).

INTRODUCTION: PF-06438179, a potential biosimilar to Remicade® (infliximab, Janssen Biotech, Inc.), is a chimeric mouse-human monoclonal antibody targeting human tumor necrosis factor alpha (TNF). METHODS: Analytical (small subset reported here) and nonclinical studies compared the structural, functional, and in vivo nonclinical similarity of PF-06438179 with Remicade sourced from the United States (infliximab-US) and/or European Union (infliximab-EU). RESULTS: The peptide map profiles were superimposable, and peptide masses were the same, indicating identical amino acid sequences. Data on post-translational modifications, biochemical properties, and biological function provided strong support for analytical similarity. Administration of a single intravenous (IV) dose (10 or 50 mg/kg) of PF-06438179 or infliximab-EU to male rats was well tolerated. There were no test article-related clinical signs or effects on body weight or food consumption. Systemic exposures [maximum drug concentration (C max) and area under the concentration-time curve (AUC)] in rats administered PF-06438179 or infliximab-EU were similar, with mean exposure ratio of PF-06438179 relative to infliximab-EU ranging from 0.88 to 1.16. No rats developed anti-drug antibodies. A 2-week IV toxicity study was conducted with once-weekly administration of 10 or 50 mg/kg of PF-06438179 to male and female rats. PF-06438179-related hyperplasia of sinusoidal cells occurred in the liver in rats administered 50 mg/kg, but was not adverse based on its minimal to mild severity. The no-observed adverse-effect level for PF-06438179 was 50 mg/kg. At this dose, C max was 1360 µg/mL and AUC at 168 h was 115,000 µg h/mL on day 8. CONCLUSIONS: The analytical and nonclinical studies have supported advancement of PF-06438179 into global comparative clinical trials. FUNDING: Pfizer Inc.

Undifferentiated myxoid lipoblastoma with PLAG1-HAS2 fusion in an infant; morphologically mimicking primitive myxoid mesenchymal tumor of infancy (PMMTI)--diagnostic importance of cytogenetic and molecular testing and literature review.

Lipoblastoma is a benign myxoid neoplasm arising in young children that typically demonstrates adipose differentiation. It is often morphologically indistinguishable from primitive myxoid mesenchymal tumor of infancy (PMMTI), which is characterized by a well-circumscribed myxoid mass with a proliferation of primitive mesenchymal cells with mild cytologic atypia. PMMTI occurs in the first year of life and is known to have locally aggressive behavior. No specific genetic rearrangements have been reported to date. In contrast, the presence of PLAG1 (Pleomorphic Adenoma Gene 1) rearrangement is diagnostic for lipoblastoma. We hereby demonstrate the combined application of multiple approaches to tackle the diagnostic challenges of a rapidly growing neck tumor in a 3-month-old female. An incisional tumor biopsy had features of an undifferentiated, myxoid mesenchymal neoplasm mimicking PMMTI. However, tumor cells showed diffuse nuclear expression by immunohistochemical (IHC) stain. Conventional cytogenetic and fluorescence in situ hybridization (FISH) analyses as well as next generation sequencing (NGS) demonstrated evidence of PLAG1 rearrangement, confirming the diagnosis of lipoblastoma. This experience warrants that undifferentiated myxoid lipoblastoma can mimic PMMTI, and the combination of cytogenetic and molecular approaches is essential to distinguish these two myxoid neoplasms. Literature on lipoblastomas with relevant molecular and cytogenetic findings is summarized. Our case is the first lipoblastoma diagnosed with a PLAG1 fusion defined by NGS technology.

Integration of cytogenomic data for furthering the characterization of pediatric B-cell acute lymphoblastic leukemia: a multi-institution, multi-platform microarray study.

It is well documented that among subgroups of B-cell acute lymphoblastic leukemia (B-ALL), the genetic profile of the leukemic blasts has significant impact on prognosis and stratification for therapy. Recent studies have documented the power of microarrays to screen genome-wide for copy number aberrations (CNAs) and regions of copy number-neutral loss of heterozygosity (CNLOH) that are not detectable by G-banding or fluorescence in situ hybridization (FISH). These studies have involved application of a single array platform for the respective cases. The present investigation demonstrates the feasibility and usefulness of integrating array results from multiple laboratories (ARUP, The Children's Hospital of Philadelphia, Cincinnati Children's Hospital Medical Center, and University of Minnesota Medical Center) that utilize different array platforms (Affymetrix, Agilent, or Illumina) in their respective clinical settings. A total of 65 patients enrolled on the Children's Oncology Group (COG) study AALL08B1 were identified for study, as cytogenetic and FISH studies had also been performed on these patients, with a central review of those results available for comparison. Microarray data were first analyzed by the individual laboratories with their respective software systems; raw data files were then centrally validated using NEXUS software. The results demonstrated the added value of integrating multi-platform data with cytogenetic and FISH data and highlight novel findings identified by array including the co-occurrence of low and high risk abnormalities not previously reported to coexist within a clone, novel regions of chromosomal amplification, clones characterized by numerous whole chromosome LOH that do not meet criteria for doubling of a near-haploid, and characterization of array profiles associated with an IKZF1 deletion. Each of these findings raises questions that are clinically relevant to risk stratification.

Rationale for the Cytogenomics of Cardiovascular Malformations Consortium: A Phenotype Intensive Registry Based Approach.

Cardiovascular malformations (CVMs) are the most common birth defect, occurring in 1%-5% of all live births. Although the genetic contribution to CVMs is well recognized, the genetic causes of human CVMs are identified infrequently. In addition, a failure of systematic deep phenotyping of CVMs, resulting from the complexity and heterogeneity of malformations, has obscured genotype-phenotype correlations and contributed to a lack of understanding of disease mechanisms. To address these knowledge gaps, we have developed the Cytogenomics of Cardiovascular Malformations (CCVM) Consortium, a multi-site alliance of geneticists and cardiologists, contributing to a database registry of submicroscopic genetic copy number variants (CNVs) based on clinical chromosome microarray testing in individuals with CVMs using detailed classification schemes. Cardiac classification is performed using a modification to the National Birth Defects Prevention Study approach, and non-cardiac diagnoses are captured through ICD-9 and ICD-10 codes. By combining a comprehensive approach to clinically relevant genetic analyses with precise phenotyping, the Consortium goal is to identify novel genomic regions that cause or increase susceptibility to CVMs and to correlate the findings with clinical phenotype. This registry will provide critical insights into genetic architecture, facilitate genotype-phenotype correlations, and provide a valuable resource for the medical community.

Comparative nonclinical assessments of the proposed biosimilar PF-05280014 and trastuzumab (Herceptin(®)).

BACKGROUND AND OBJECTIVES: Trastuzumab (Herceptin(®)) is a humanized monoclonal antibody (mAb) that binds to the HER2 protein. PF-05280014 is being developed as a potential biosimilar to trastuzumab products marketed in the United States (trastuzumab-US) and European Union (trastuzumab-EU). Nonclinical studies were designed to evaluate the similarity of PF-05280014 to trastuzumab-US and trastuzumab-EU using in vitro structural and functional analyses, and in vivo pharmacokinetic and immunogenicity assessments. METHODS: Peptide mapping was utilized to determine structural similarity. Functional similarity was assessed via an in vitro tumor cell growth inhibition assay. CD-1 male mice were administered a single-dose (0, 1, 10, or 100 mg/kg) of PF-05280014, trastuzumab-US, or trastuzumab-EU. Mice were monitored for clinical signs and body weight changes over a 4-month period. At approximately 720, 1,080, 1,440, 2,160, and 2,880 h post-dose, terminal blood samples were collected and assayed for PF-05280014, trastuzumab-US, or trastuzumab-EU concentrations and anti-drug antibodies (ADA). Values for C max, area under the concentration time curve (AUC), clearance (CL), volume of distribution (V ss), half-life (t ½), and the presence of ADA were determined. RESULTS: In this report, peptide mapping of PF-05280014, trastuzumab-US, and trastuzumab-EU showed similar chromatographic profiles in a side-by-side analysis. The tumor cell growth inhibition of PF-05280014 was similar to trastuzumab-US and trastuzumab-EU. C max and AUC0-∞ values in mice were similar and dose-dependent across the mAbs at all doses, and CL and V ss values were similar and dose-independent. The CL values across doses ranged from 0.193 to 0.350 mL/h/kg (PF-05280014), from 0.200 to 0.346 mL/h/kg (trastuzumab-US), and from 0.193 to 0.335 mL/h/kg (trastuzumab-EU). V ss values across doses ranged from 84.9 to 120 mL/kg (PF-05280014), 86.7 to 130 mL/kg (trastuzumab-US), and 85.4 to 116 mL/kg (trastuzumab-EU). The incidence of ADA was low (~10%) and also similar across all dose levels and the three mAbs. The lower exposure generally observed in ADA-positive animals did not impact the overall PK interpretation. All animals survived to their scheduled terminal blood collection with no mAb-related differences in body weight gain or clinical signs. CONCLUSIONS: PF-05280014, trastuzumab-US, and trastuzumab-EU were well tolerated during the 4-month observation period following a single dose of up to 100 mg/kg. PF-05280014, trastuzumab-US, and trastuzumab-EU showed similar structural properties, tumor cell growth inhibition properties, and PK profiles. The incidence of ADA was low and similar across the three mAbs. The results of these studies support the development of PF-05280014 as a proposed biosimilar to Herceptin.