Cancer continues to be a major global health burden. Despite progress in the treatment of cancer, there continues to be an unmet medical need for more effective and less toxic therapies, especially for those patients with advanced disease or cancers that are resistant to existing therapeutics.
The role of the immune system, in particular T cell-mediated cytotoxicity, in tumor control is well recognized. There is mounting evidence that T cells control tumor growth and survival in cancer patients, both in early and late stages of the disease. However, tumor-specific T-cell responses are difficult to mount and sustain in cancer patients. The continuing advancement and successes of cancer immunotherapies, which stimulate or enhance innate immune responses against cancer, make such therapeutics an attractive treatment option when compared to therapies that utilize non-specific chemotherapeutics and/or radiation.
A number of molecular targets have been identified for their potential utility as immuno-oncology (IO) therapeutics against cancer. Some molecular targets that are being investigated for their therapeutic potential in the area of immuno-oncology therapy include cytotoxic T lymphocyte antigen-4 (CTLA-4 or CD152), programmed death ligand 1 (PD-L1 or B7-H1 or CD274), Programmed Death-1 (PD-1), OX40 (CD134 or TNFRSF4) and T-cell inhibitory receptor T-cell immunoglobulin and mucin-domain containing-3 (TIM3). While some of these targets have been successfully exploited therapeutically (e.g., PD-1 and CTLA-4), many patients have been unresponsive to the therapeutics that have been developed. And, while a therapeutic regimen that includes higher doses and/or a combination of immunotherapies may be considered, such therapies may be associated with increased risk of side effects, which tend to increase with higher doses and cumulative exposure, and appear to be additive when used with combination immunotherapies. Some common side effects include hypophysitis, thyroiditis, adrenal insufficiency, enterocolitis, dermatitis, pneumonitis, hepatitis, pancreatitis, motor and sensory neuropathies, and arthritis. Furthermore, as immunotherapeutics are typically associated with high costs, a therapy that includes a combination of immunotherapeutics can be cost-prohibitive to patients.
As such, there remains a need to continue to identify candidate targets for IO therapeutics, develop new therapeutics to the existing targets, and to develop therapeutic strategies that avoid disadvantages of immunotherapies that are currently in use, including the lack of patient response and the increased risk of side effects involved with combination treatment. IO therapeutics (e.g., binding proteins) that are bispecific for a combination of target molecules, particularly those that exhibit greater binding affinity for the target molecules when compared to the binding affinity for a combination of individual monospecific binding proteins, represent a class of particularly desirable molecules for therapeutic potential.