Impact of IgG subclass on monoclonal antibody developability.

IgG-based monoclonal antibody therapeutics, which are mainly IgG1, IgG2, and IgG4 subclasses or related variants, have dominated the biotherapeutics field for decades. Multiple laboratories have reported that the IgG subclasses possess different molecular characteristics that can affect their developability. For example, IgG1, the most popular IgG subclass for therapeutics, is known to have a characteristic degradation pathway related to its hinge fragility. However, there remains a paucity of studies that systematically evaluate the IgG subclasses on manufacturability and long-term stability. We thus conducted a systematic study of 12 mAbs derived from three sets of unrelated variable regions, each cloned into IgG1, an IgG1 variant with diminished effector functions, IgG2, and a stabilized IgG4 variant with further reduced FcγR interaction, to evaluate the impact of IgG subclass on manufacturability and high concentration stability in a common formulation buffer matrix. Our evaluation included Chinese hamster ovary cell productivity, host cell protein removal efficiency, N-linked glycan structure at the conserved N297 Fc position, solution appearance at high concentration, and aggregate growth, fragmentation, charge variant profile change, and post-translational modification upon thermal stress conditions or long-term storage at refrigerated temperature. Our results elucidated molecular attributes that are common to all IgG subclasses, as well as those that are unique to certain Fc domains, providing new insight into the effects of IgG subclass on antibody manufacturability and stability. These learnings can be used to enable a balanced decision on IgG subclass selection for therapeutic antibodies and aid in acceleration of their product development process.

Impact of IgG subclass on molecular properties of monoclonal antibodies.

Immunoglobulin G-based monoclonal antibodies (mAbs) have become a dominant class of biotherapeutics in recent decades. Approved antibodies are mainly of the subclasses IgG1, IgG2, and IgG4, as well as their derivatives. Over the decades, the selection of IgG subclass has frequently been based on the needs of Fc gamma receptor engagement and effector functions for the desired mechanism of action, while the effect on drug product developability has been less thoroughly characterized. One of the major reasons is the lack of systematic understanding of the impact of IgG subclass on the molecular properties. Several efforts have been made recently to compare molecular property differences among these IgG subclasses, but the conclusions from these studies are sometimes obscured by the interference from variable regions. To further establish mechanistic understandings, we conducted a systematic study by grafting three independent variable regions onto human IgG1, an IgG1 variant, IgG2, and an IgG4 variant constant domains and evaluating the impact of subclass and variable regions on their molecular properties. Structural and computational analysis revealed specific molecular features that potentially account for the differential behavior of the IgG subclasses observed experimentally. Our data indicate that IgG subclass plays a significant role on molecular properties, either through direct effects or via the interplay with the variable region, the IgG1 mAbs tend to have higher solubility than either IgG2 or IgG4 mAbs in a common pH 6 buffer matrix, and solution behavior relies heavily on the charge status of the antibody at the desirable pH.

Candida spp. Determination and Th1/Th2 Mixed Cytokine Profile in Oral Samples From HIV+ Patients With Chronic Periodontitis.

Background: Chronic periodontitis (CP), caused by bacteria and fungi, appears in up to 66% of HIV-patients. The impact and association of HIV-treatment (HAART) and Candida itself has not been properly evaluated in the development and progression of CP. The immunopathogenesis is characterized by CD4+ T-cells activation and the balance between the T-helper 1 (Th1) and T-helper 2 (Th2) or a mixed cytokine profile. Currently, the associated causes of an immune response in HIV-patients with CP is controversial. Our aims were the determination of Candida spp. and cytokine profile in oral samples from HIV-positive patients with CP, considering the CD4+ T cells levels and HAART use. Methods: From 500 HIV-positive patients evaluated, 228 patients were enrolled. Patients were separated in groups: (A) n = 53 (≤200 CD4+ T-cells on HAART); (B) n = 57 (≤200 CD4+ T-cells without HAART); (C) n = 50 (>200 CD4+ T-cells without HAART); (D) n = 68 (>200 CD4+ T-cells on HAART). Candida spp. were isolated from the oral biofilm and crevicular fluid in CHROMagar and confirmed by endpoint PCR. Cytokine levels were measured by beads-based immunoassay in saliva by flow cytometry. Results: 147 patients (64.5%) were positive to Candida spp. and 204 strains were isolated; 138 (67.6%) were C. albicans and the remaining C. non-albicans species (C. glabrata>C. tropicalis>C. krusei>C. dubliniensis). In this study, CHROMagar showed good sensitivity (95%) but poor specificity (68%); since of the 152 samples identified as C. albicans, only 131 were confirmed by PCR; from the 10 samples identified as C. glabrata, only six were confirmed. Finally, of the 42 samples detected as C. tropicalis, only five were confirmed. When evaluating Candida spp. presence, group A and D had higher isolation, while group B had the highest species diversity. Whereas, group C had a significant reduction of Candida spp. Despite the presence of Candida and HAART, we found a Th1/Th2 hybrid profile in the saliva of patients with low CD4+ T-cell count (group A). Conclusion: Abundance and diversity of the Candida spp. detected in HIV-patients with CP could be related to HAART and low CD4+ T-cells levels. Also, the immunosuppression might promote a local Th1/Th2 hybrid cytokine profile.

Prevalencia de la xerostomía y su asociación con síndromes geriátricos en pacientes ancianos que asisten a un centro de atención de primer nivel / Prevalence of the xerostomia and its association with geriatric syndromes in elderly patients who assist to a primary care level center

RESUMEN Antecedentes: A nivel mundial la población envejecida está aumentando y esto es seguido por un aumento en resultados negativos llamados síndromes geriátricos (SG). Un elemento clave del envejecimiento exitoso es la salud oral (SO). La alteración en los componentes de OH, como la presencia de xerostomía, se ha asociado con una mayor probabilidad de desarrollar algunos SG. Objetivos: Determinar la prevalencia de la xerostomía y sus asociaciones entre las características sociodemográfi cas, el estado de salud y algunos GS en adultos de 60 años o más, que asisten a consulta de primer nivel en México. Material y métodos: Estudio transversal en participantes de 60 años o más, reclutados en 2016. Los participantes se sometieron a una evaluación geriátrica integral (EGI), con la que se obtuvo el diagnóstico de xerostomía y SG. Se determinaron los análisis de regresión ajustados por las variables de confusión para establecer la asociación entre la xerostomía, las características sociodemográfi cas y algunos SG. Resultados: Se incluyeron 264 sujetos; la edad media fue de 73 años (DE ± 6), las mujeres representaron el 60%. En general, el 33% informó la presencia de xerostomía. Después de ajustar por edad, sexo y lectoescritura, los análisis de regresión logística múltiple mostraron una asociación signifi cativa entre la xerostomía y algunos SG (depresión y dolor). Conclusión: Este estudio mostró que la prevalencia de xerostomía es mayor en ancianos mexicanos. Estos resultados sugieren la importancia de monitorear el deterioro de la salud oral, ya que la xerostomía parece tener una infl uencia negativa en el estado de salud de los ancianos, y que la evaluación de la xerostomía debe incluirse en la evaluación geriátrica para prevenir los SG.

ABSTRACT Background: Worldwide aged population is increasing and this is followed by an increase a in negative outcome called geriatric syndromes (GS). A key element of a successful aging is oral health (OH). Alteration of OH components, such as the presence of xerostomia, have been associated with a higher probability of develop some GS. Objectives: Determine the prevalence of xerostomia and its associations between the sociodemographic characteristics, the state of health and some GS in adults of 60 years or older, who attend fi rst level consultation in Mexico. Material and methods: Transverse study in participants of 60 years or more, recruited in 2016. The participants underwent an integral geriatric evaluation (IGE), with which the diagnosis of xerostomia and GS was obtained. The adjusted regression analysis were determined by the confounding variables to establish the association between xerostomia, sociodemographic characteristics and some GS. Results: 264 subjects were included; the average age was 73 years (SD ± 6), women accounted for 60%. In general, 33% reported the presence of xerostomia. After adjusting for age, sex and literacy, multiple logistic regression analysis showed a signifi cant association between xerostomia and some GS (depression and pain). Conclusion: This study showed that the prevalence of xerostomia is higher in mexican elderly. These results suggest the importance of monitoring the deterioration of oral health, since xerostomia seems to have a negative infl uence on the state of health of the elderly and that the evaluation of xerostomia should be included in the geriatric assessment to prevent GS.