Contributions
Abstract: P657
Type: Poster
Abstract Category: Therapy - disease modifying - 26 Immunomodulation/Immunosuppression
Background: Ofatumumab is the first fully human, subcutaneous, anti-CD20 monoclonal antibody in Phase 3 development for MS. In cynomolgus monkeys, treatment with human equivalent subcutaneous (s.c.) doses of ofatumumab resulted in potent B-cell depletion in both blood and tissues. Studies in this model allow parallel comparison of blood and tissue effects. Ongoing immunophenotyping focuses on ofatumumab mode of action.
Objective: To compare changes of lymphocyte subsets in blood and lymph nodes (LN) and changes in lymph node morphology and distribution of lymphocyte subsets in ofatumumab-treated cynomolgus monkeys.
Methods: Axillary LN and blood were collected on Days 0, 21, 62 and 90. Further tissues were collected upon termination on Day 90. Fluorescence-activated cell sorting (FACS) analysis enabled quantitation of lymphocyte subsets in blood, spleen and various LN. Morphological evaluation and quantitative imaging-based immunophenotyping of LN were performed using immunohistochemistry (IHC) or in-situ hybridisation (ISH) for individual B- and T-cell markers or imaging mass cytometry (IMC) for the detection of multiple markers on the same tissue section.
Results: Various subsets of B-cells were differentially affected by low dose ofatumumab s.c. in cynomolgus monkeys, while the total number of B cells was potently and rapidly reduced. Absolute numbers of marginal zone (MZ) B cells in axillary LN increased with ofatumumab treatment. All B-cell subsets in blood and tissues were BAFFR positive which may be relevant to B-cell repletion kinetics. In addition, there was a sharp decline in CD20+CD3+ T cells followed by full recovery in the treatment-free period. Preliminary IMC results confirmed that the CD8 T cells in blood and LN decreased early after treatment initiation but recovered by Day 90. At Day 21, B-cell IHC revealed depletion of the perifollicular and interfollicular area of axillary LN, while the core of CD20+CD21+ cells LN follicles was detectable. At Day 62, the perifollicular and interfollicular areas became abundantly infiltrated by CD21+ B cells. At Day 90, LN showed high expression of CD27 mRNA and a return to baseline cytoarchitecture arrangement.
Conclusions: Low dose s.c. ofatumumab potently depleted both B cells and CD20+ T cells in blood and LN. However, MZ B cells, a subset relevant for immune defence, were spared from depletion.
Disclosure: This study was funded by Novartis Pharma AG, Basel, Switzerland.All authors are employees of Novartis. Paul Smith was an employee of Novartis at the time of study conduct.
Abstract: P657
Type: Poster
Abstract Category: Therapy - disease modifying - 26 Immunomodulation/Immunosuppression
Background: Ofatumumab is the first fully human, subcutaneous, anti-CD20 monoclonal antibody in Phase 3 development for MS. In cynomolgus monkeys, treatment with human equivalent subcutaneous (s.c.) doses of ofatumumab resulted in potent B-cell depletion in both blood and tissues. Studies in this model allow parallel comparison of blood and tissue effects. Ongoing immunophenotyping focuses on ofatumumab mode of action.
Objective: To compare changes of lymphocyte subsets in blood and lymph nodes (LN) and changes in lymph node morphology and distribution of lymphocyte subsets in ofatumumab-treated cynomolgus monkeys.
Methods: Axillary LN and blood were collected on Days 0, 21, 62 and 90. Further tissues were collected upon termination on Day 90. Fluorescence-activated cell sorting (FACS) analysis enabled quantitation of lymphocyte subsets in blood, spleen and various LN. Morphological evaluation and quantitative imaging-based immunophenotyping of LN were performed using immunohistochemistry (IHC) or in-situ hybridisation (ISH) for individual B- and T-cell markers or imaging mass cytometry (IMC) for the detection of multiple markers on the same tissue section.
Results: Various subsets of B-cells were differentially affected by low dose ofatumumab s.c. in cynomolgus monkeys, while the total number of B cells was potently and rapidly reduced. Absolute numbers of marginal zone (MZ) B cells in axillary LN increased with ofatumumab treatment. All B-cell subsets in blood and tissues were BAFFR positive which may be relevant to B-cell repletion kinetics. In addition, there was a sharp decline in CD20+CD3+ T cells followed by full recovery in the treatment-free period. Preliminary IMC results confirmed that the CD8 T cells in blood and LN decreased early after treatment initiation but recovered by Day 90. At Day 21, B-cell IHC revealed depletion of the perifollicular and interfollicular area of axillary LN, while the core of CD20+CD21+ cells LN follicles was detectable. At Day 62, the perifollicular and interfollicular areas became abundantly infiltrated by CD21+ B cells. At Day 90, LN showed high expression of CD27 mRNA and a return to baseline cytoarchitecture arrangement.
Conclusions: Low dose s.c. ofatumumab potently depleted both B cells and CD20+ T cells in blood and LN. However, MZ B cells, a subset relevant for immune defence, were spared from depletion.
Disclosure: This study was funded by Novartis Pharma AG, Basel, Switzerland.All authors are employees of Novartis. Paul Smith was an employee of Novartis at the time of study conduct.