Characterization and non-clinical assessment of the proposed etanercept biosimilar GP2015 with originator etanercept (Enbrel(®)).

BACKGROUND AND OBJECTIVE: Biosimilars are approved biologics that are comparable to an originator product with respect to quality, safety and efficacy. Herein, the authors describe the functional and non-clinical studies designed to determine the biosimilarity of GP2015 and originator etanercept (Enbrel®). METHODS: The development of an Enbrel biosimilar (GP2015) involved extensive characterization of the originator. A step-wise target-directed and iterative technical development program involving state-of-the-art functional characterization studies and non-clinical evaluations (pharmacokinetics, pharmacodynamics and safety/toxicology) was applied with the aim of confirming that GP2015 is comparable to originator (Enbrel) at the non-clinical level. RESULTS: In in vitro tests, GP2015 and Enbrel had comparable binding affinities to TNF-α, C1q complement and a complete panel of Fc-Receptors. Comprehensive functional characterization testing confirmed the comparability of GP2015 with Enbrel in terms of its ability to bind to and neutralize TNF-α, which reflects the primary mechanism of action of etanercept. Non-clinical data confirmed that the proposed biosimilar to Enbrel, GP2015, is comparable with regards to its pharmacokinetic properties and pharmacodynamic activity, and efficacy as well as safety/toxicity. CONCLUSION: The proposed Enbrel biosimilar, GP2015, was shown to be comparable to its originator product in studies designed to confirm biosimilarity.

Development of a quantitative, cell-line based assay to measure ADCC activity mediated by therapeutic antibodies.

Antibody-dependent cellular cytotoxicity (ADCC) contributes to clinical efficacy of a broad range of antibody therapeutics. However, reproducible quantitation of ADCC activity on a cellular level remains highly challenging, as ADCC assays rely on primary effector cells associated with laborious cell purification procedures, resulting in highly donor-dependent results. Here, we report the development of an in vitro ADCC method based on an engineered human natural killer cell line as effectors. While eliminating the limitations of primary cells, this assay exhibits all the hallmarks of traditional ADCC assay systems. We have used this assay to measure the ADCC activity of a humanized IgG1 antibody directed against the human CD20 antigen. Our data show that this assay is capable to measure small changes in ADCC and can therefore be used to test therapeutic antibodies against cell-surface targets for their depleting activity.

Increasing the efficacy of CD20 antibody therapy through the engineering of a new type II anti-CD20 antibody with enhanced direct and immune effector cell-mediated B-cell cytotoxicity.

CD20 is an important target for the treatment of B-cell malignancies, including non-Hodgkin lymphoma as well as autoimmune disorders. B-cell depletion therapy using monoclonal antibodies against CD20, such as rituximab, has revolutionized the treatment of these disorders, greatly improving overall survival in patients. Here, we report the development of GA101 as the first Fc-engineered, type II humanized IgG1 antibody against CD20. Relative to rituximab, GA101 has increased direct and immune effector cell-mediated cytotoxicity and exhibits superior activity in cellular assays and whole blood B-cell depletion assays. In human lymphoma xenograft models, GA101 exhibits superior antitumor activity, resulting in the induction of complete tumor remission and increased overall survival. In nonhuman primates, GA101 demonstrates superior B cell-depleting activity in lymphoid tissue, including in lymph nodes and spleen. Taken together, these results provide compelling evidence for the development of GA101 as a promising new therapy for the treatment of B-cell disorders.

Direct genetic analysis of single disseminated cancer cells for prediction of outcome and therapy selection in esophageal cancer.

The increasing use of primary tumors as surrogate markers for prognosis and therapeutic decisions neglects evolutionary aspects of cancer progression. To address this problem, we studied the precursor cells of metastases directly for the identification of prognostic and therapeutic markers and prospectively analyzed single disseminated cancer cells from lymph nodes and bone marrow of 107 consecutive esophageal cancer patients. Whole-genome screening revealed that primary tumors and lymphatically and hematogenously disseminated cancer cells diverged for most genetic aberrations. However, we identified chromosome 17q12-21, the region comprising HER2, as the most frequent gain in disseminated tumor cells that were isolated from both ectopic sites. Survival analysis demonstrated that HER2 gain in a single disseminated tumor cell but not in primary tumors conferred high risk for early death.

Cytotoxic activity of natural killer cells lacking killer-inhibitory receptors for self-HLA class I molecules against autologous hematopoietic stem cells in healthy individuals.

Killer-inhibitory receptors (KIR) are receptors for self-HLA class I molecules, which are expressed on natural killer (NK) cells and small subsets of T-lymphocytes. KIR receptors that do not bind to self-HLA class I have been implicated in the pathogenesis of pure red-cell aplasia and other autoimmune diseases. However, NK cells whose inhibitory receptors lack any apparent self-ligand can also be found in healthy individuals. We therefore tested whether these NK cells are capable of exerting cytotoxic activity against autologous CD34(+) hematopoietic precursors. We detected NK cells whose sole inhibitory receptors were CD94/NKG2-A and that had no affinity for autologous HLA-C molecules. In vitro, such cells were able to kill autologous CD34(+) stem cells that expressed MHC class I antigen at a high level in about 50% of the cases of HLA-C group 2 donors. Two individual clones derived from this NK subpopulation were stimulated by autologous HLA-Cw5/6-positive stem cells, but not by allogeneic HLA-Cw7-positive stem cells. Our findings demonstrate the presence of potentially autoreactive natural killer cells in otherwise healthy individuals.