Advances in biotechnology have made it possible to produce a variety of proteins for pharmaceutical applications using recombinant DNA techniques. Because proteins are larger and more complex than traditional organic and inorganic drugs (i.e., possessing multiple functional groups in addition to complex three-dimensional structures), the formulation of such proteins poses special problems. For a protein to remain biologically active, a formulation must preserve the conformational integrity of at least a core sequence of the protein's amino acids, while at the same time protecting the protein's multiple functional groups from degradation. Proteins may suffer from a lack of stability, and monoclonal and polyclonal antibodies in particular may be relatively unstable (See e.g., Wang, et al., J. Pharm Sci. 96:1-26 (2007)). A large number of formulation options are available, and not one approach or system is suitable for all proteins. Several factors to be considered have been reported (See e.g., Wang et al.).
Numerous characteristics may affect a protein's stability. In fact, even in the case of purified antibodies, the antibody structures may be heterogenous, which further complicates the formulation of such systems. Moreover, the excipients included in antibody formulations preferably minimize any potential immune response.
In the case of antibodies, preservation of the conformational integrity is even more important. Degradation pathways for proteins can involve chemical instability (i.e., any process which involves modification of the protein by bond formation or cleavage resulting in a new chemical entity) or physical instability (i.e., changes in the higher order structure of the protein). Chemical instability is manifested in, for example, deamidation, isomerization, hydrolysis, oxidation, fragmentation, glycan beta elimination or disulfide exchange. Physical instability can result from denaturation, aggregation, precipitation or adsorption, for example. The four most common protein degradation pathways are protein fragmentation, aggregation, deamidation, and oxidation. Consequences of chemical or physical instability of therapeutic protein include a lowering of the effective administered dose, decreased safety of the therapy due to, for example irritation or immunological reactivity, and more frequent manufacturing due to short shelf life.
Several publications have disclosed generally various methods of treating inflammatory bowel diseases, and provided dosing schemes for administration of agents designed to treat inflammatory bowel disease. For example, WO 96/24673 discloses mucosal vascular addressins and treatment of diseases associated with leukocyte recruitment to the gastrointestinal tract as a result of leukocyte binding to cells expressing MAdCAM. U.S. 2005/0095238 describes methods of treating a disease associated with leukocyte infiltration of mucosal tissue and administration to a human an effective amount of a human or humanized immunoglobulin or antigen binding fragment having binding specificity for α4β7 integrin. U.S. 2005/0095238 further describes various doses (e.g. 0.15, about 0.5, about 1.0, about 1.5 or about 2.0 mg immunoglobulin or fragment per kg body weight) and various intervals between doses (7, 14, 21, 28, or 30 days). However, the aforementioned patents and publications do not disclose specific formulations of the anti-α4β7 antibody or the specific doses and dose regimens described and claimed herein. Importantly, the aforementioned patents do not disclose formulations, doses, and dose regimens that provide for the methods of treatment (supported by clinical trial data) described and claimed herein.
The antibody formulations of the present invention may be useful for inhibiting leukocyte binding to cells expressing MAdCAM and therefore aid in treatment of inflammatory bowel diseases in patients. There is, accordingly, an urgent need to discover suitable dosages and dosing schedules of these compounds, and to develop formulations, preferably subcutaneous formulations, which give rise to steady, therapeutically effective blood levels of the antibody formulations over an extended period of time in a stable and convenient form.