Multifaceted assessment of rituximab biosimilarity: The impact of glycan microheterogeneity on Fc function.

Biosimilars are poised to reduce prices and increase patient access to expensive, but highly effective biologic products. However, questions still remain about the degree of similarity and scarcity of information on biosimilar products from outside of the US/EU in the public domain. Thus, as an independent entity, we performed a comparative analysis between the innovator, Rituxan® (manufactured by Genentech/Roche), and a Russian rituximab biosimilar, Acellbia® (manufactured by Biocad). We evaluated biosimilarity of these two products by a variety of state-of-the-art analytical mass spectrometry techniques, including tandem MS mapping, HX-MS, IM-MS, and intact MS. Both were found to be generally similar regarding primary and higher order structure, though differences were identified in terms of glycoform distribution levels of C-terminal Lys, N-terminal pyroGlu, charge variants and soluble aggregates. Notably, we confirmed that the biosimilar had a higher level of afucosylated glycans, resulting in a stronger FcγIIIa binding affinity and increased ADCC activity. Taken together, our work provides a comprehensive comparison of Rituxan® and Acellbia®.

Assessment of the clinicopathological relevance of mesothelin level in plasma, peritoneal fluid, and tumor tissue of epithelial ovarian cancer patients.

Ovarian cancer remains the most lethal gynecologic malignancy. This is due to lack of effective screening, diagnosis predominance in late stage of disease, a high recurrence rate after primary therapy, and poor treatment response in platinum-resistant tumor. Thus, unique biomarkers, predictive of individual disease course, and prognosis are urgently needed. The aim of our study was to assess the clinicopathological significance of plasma, peritoneal fluid, and tumor tissue levels of mesothelin in epithelial ovarian cancer patients. Plasma and peritoneal fluid levels of mesothelin were measured by enzyme-linked immunosorbent assay. Tissue expression of MSLN was evaluated using quantitative real-time polymerase chain reaction. Preoperative plasma mesothelin levels were significantly higher in epithelial ovarian cancer patients in comparison to the patients with benign tumor and controls. There have been noticed significant differences in the plasma mesothelin levels based on International Federation of Gynecology and Obstetrics stage, grade, and histology type. No significant changes were observed between Kurman and Shih type I versus type II epithelial ovarian cancer. Interestingly, peritoneal fluid mesothelin levels revealed significant differences based on both grade and Kurman and Shih-type epithelial ovarian cancer. There were no relevant changes in the mesothelin level in peritoneal fluid between different stages and histology types compared to benign tumor. MSLN expression level in tumor tissue was significantly higher based on stage, grade, and Kurman and Shih-type epithelial ovarian cancer than in the benign masses. In addition, data showed significant higher MSLN expression in endometrioid tumors compared to benign masses and serous tumors. Plasma, peritoneal fluid, and tumor tissue levels of mesothelin positively correlated with level of CA125. Low mesothelin concentrations in plasma were also associated with prolonged patient survival. More importantly, we revealed that plasma mesothelin level was correlated with both peritoneal fluid mesothelin level and tumor MSLN expression. This study highlights that plasma mesothelin level may be a useful noninvasive biomarker surrogate for local tumor mesothelin status in monitoring of epithelial ovarian cancer patients.

Clinical relevance of CD157 for rapid and cost-effective simultaneous evaluation of PNH granulocytes and monocytes by flow cytometry.

INTRODUCTION: CD157 has been reported as a potentially useful marker for paroxysmal nocturnal hemoglobinuria (PNH) testing by flow cytometry (FCM). METHODS: We determined the performance characteristics of a CD157-based five-color assay and compared results from patient analysis with results obtained with a previously validated CD14/CD24-based six-color protocol. RESULTS: Coefficient of variation (CV) for intra-/interassay precision analysis of granulocytes ranged from 0.88/0.09% to 3.02/3.71% and from 0.20/0.08% to 8.83/4.04% for the five- and six-color protocol, respectively. For monocyte, CV ranged from 0.42/0.49% to 8.13/4.80% for the five-color protocol and from 0.28/0.70% to 5.41/3.19% for the six-color protocol within various PNH clones. Coefficient of determination (r(2) ) for linear regression analysis of PNH clones ranging from 0.3 to 99.8% was >0.99 in all cases, Wilcoxon ranks test showed no statistically significant differences (P > 0.05), and Bland-Altman analysis demonstrated agreement with mean bias ranging from -0.02 to 0.38. CONCLUSION: Our results confirm very good performance characteristics for both intra- and interassay precision analyses, excellent correlation, and agreement between approaches. In agreement with recently published data, our experience supports the clinical relevance of CD157 for a rapid and cost-effective simultaneous evaluation of PNH leukocytes by flow cytometry.

Value of vanin-1 assessment in adult patients with primary immune thrombocytopenia.

The diagnosis of primary immune thrombocytopenia (ITP) is clinical and cannot be established by any specific laboratory assay. Perhaps the best diagnostic study is assessment of the patient's response to ITP therapy. Oxidative stress-related pathways were among the most significant chronic ITP-associated pathways. Overexpression of VNN1 gene, an oxidative stress sensor in epithelial cells, was most strongly associated with progression to chronic ITP. To address this issue, we tested the hypothesis that blood vanin-1 protein level could distinguish between chronic responders and non-responders ITP patients as well as between ITP patients and healthy controls. Vanin-1 protein levels were determined in peripheral blood leukocytes of 80 adult subjects (16 newly diagnosed ITP patients, 24 chronic responders ITP patients, 24 chronic non-responders ITP patients and 16 healthy controls) by enzyme-linked immunesorbent assay (ELISA). Blood vanin-1 protein levels were lower in controls (median = 18.39 ng) than in ITP patients (median = 58.78 ng) with a highly significant p value (p < 0.001). Vanin-1 levels were highly significantly elevated in newly diagnosed ITP patients (median = 188.62 ng) in comparison to chronic responders (median= 26.90 ng) and chronic non-responders (median = 73.87 ng). Vanin-1 level at a cut-off value of >20.73 ng was found to be 100% sensitive and 93.7% specific in discriminating between newly diagnosed ITP patients and healthy controls. Vanin-1 level was found to be 100% sensitive and 100% specific in differentiating between responders and non-responders with a cut-off value of ≤ 34.5 ng. Our results suggest that vanin-1 can distinguish between chronic responders and non-responders ITP patients as well as between newly diagnosed ITP patients and healthy controls. These findings demonstrate that vanin-1 may contribute to the pathogenesis of ITP, indicating that vanin-1 is an important target for further investigation.

Corelease of dopamine and GABA by a retinal dopaminergic neuron.

Numerous neurons release two transmitters of low molecular mass, but it is controversial whether they are localized within the same synaptic vesicle, with the single exception of GABA and glycine because they are ferried into the vesicle by the same transporter. Retinal dopaminergic (DAergic) amacrine cells synthesize both dopamine (DA) and GABA. Both transmitters are released over the entire cell surface and act on neighboring and distant neurons by volume transmission, but, in addition, DAergic cells establish GABAergic synapses onto AII amacrine cells, the neurons that transfer rod signals to cone bipolars. By combining recordings of DA and GABA release from isolated, genetically identified perikarya of DAergic cells from the mouse retina, we observed that a proportion of the events of DA and GABA exocytosis were simultaneous, suggesting corelease. Furthermore, a proportion of the secretory organelles in the perikaryon and synaptic endings of DAergic cells contained both vesicular transporters for DA [vesicular monoamine transporter 2 (VMAT2)] and GABA [vesicular GABA transporter (VGAT)]. Because the majority of the DA release events concerned a single transmitter and organelles were present that contained a single transporter, either VMAT2 or VGAT, we conclude that the secretory organelles of DAergic cells contain variable concentrations of the two transmitters, which are in turn determined by a variable mixture of the two transporter molecules in their limiting membrane. This variability can be explained if the relative numbers of transporter molecules is determined stochastically during the budding of the somatic organelles from the trans-Golgi network or the retrieval of the vesicular membrane from the plasmalemma after exocytosis.