Immunogenicity of antibody drug conjugates: bioanalytical methods and monitoring strategy for a novel therapeutic modality.

Immunogenicity (the development of an adaptive immune response reactive with a therapeutic) is a well-described but unwanted facet of biotherapeutic development. There are commonly applied procedures for immunogenicity risk assessment, testing strategies, and bioanalysis. With some modifications, these can be applied to new biotherapeutic modalities. For novel therapies such as antibody-drug conjugates (ADCs), the unique structural components may contribute additional complexities to both immunologic responses and bioanalytical methods. US product inserts (USPIs) for two commercially available ADCs detail the incidence of immunogenicity; however, the body of literature on immunogenicity of ADCs is limited. We recently participated in a conference session on this topic (Annual meeting of the American Association of Pharmaceutical Scientists, held November 2013 in San Antonio, TX, USA. The meeting featured the Symposium: Immunogenicity Assessment for Novel Antibody Drug Conjugates, Nonclinical to Clinical) which prompted an effort to share our perspectives on how immunogenicity risk assessment, testing strategies, and bioanalytical methods can be adapted to reflect the complexity of ADC therapeutics.

Synergism between clofarabine and decitabine through p53R2: a pharmacodynamic drug-drug interaction modeling.

Clofarabine (CLO), a purine nucleoside analog with promising efficacy in acute myeloid leukemia (AML), inhibits the ribonucleotidereductase, p53R2. We have shown that p53R2 mRNA is up-regulated by decitabine (DEC), another drug with promising activity in AML. We developed a pharmacodynamic model to characterize the interaction between CLO and DEC on an AML cell line and down-regulated p53R2 protein to understand its role. These results confirm a role for p53R2 in both CLO and DEC mechanism of action, demonstrate synergism between these two drugs in this AML model and support the use of this combination in a future clinical trial.