Single-domain monoclonal antibodies for the treatment of hepatocellular carcinoma

The National Cancer Institute seeks parties to license human monoclonal antibodies and immunoconjugates and co-develop, evaluate, and/or commercialize large-scale antibody production and hepatocellular carcinoma (HCC) xenograft mouse models. An advantage of these monoclonal antibodies as a potential therapeutic is their specificity, which would reduce deleterious side-effects. HCC is the most common form of liver cancer, and is among the more deadly cancers in the world. There is a need for new treatments that can be successfully applied to a large population of patients.

Antibody and Immunotoxin Treatments for Mesothelin-expressing Cancers

Mesothelin is a cell surface protein that is highly expressed in aggressive cancers such as malignant mesothelioma, ovarian cancer, pancreatic cancer, lung cancer, breast cancer, cholangiocarcinoma, bile duct carcinoma and gastric cancer. As a result, mesothelin is an excellent candidate for tumor targeted immunotherapeutics. However, the antibodies against mesothelin that are available for clinical trials are of murine origin. These antibodies have the potential to elicit immune responses in patients, which may adversely affect the ability to provide patients with repeated doses.

Increased Therapeutic Effectiveness of PE-Based Immunotoxins

Patients receiving immunotoxin cancer therapy are less likely to experience the deleterious side-effects associated with non-discriminate therapies such as chemotherapy or radiation therapy. Unfortunately, the continued administration of immunotoxins often leads to a reduced patient response due to the formation of neutralizing antibodies against immunogenic epitopes contained within Pseudomonas exotoxin A (PE). 

Monoclonal Antibodies and Immunoconjugates Directed to the Non-ShedPortion (“Stalk”) of Mesothelin are Excellent Candidates for Developing Therapeutic Agents

Human mesothelin is overexpressed by various cancers such as synovial sarcoma, mesothelioma, and ovarian, lung, esophageal, and gastric cancers. This selective expression on certain cancers suggests that mesothelin is an excellent target for anticancer therapeutics. However, a large fragment (“the shed portion”) of mesothelin is constantly shed from cells, and all current anti-mesothelin antibodies bind to the shed portion.

Improved PE-based Targeted Toxins: A Therapeutic with Increased Effectiveness

Targeted toxins (e.g., immunotoxins) are therapeutics that have at least two important components: (1) a toxin domain that is capable of killing cells and (2) a targeting domain that is capable of selectively localizing the toxic domain to only those cells which should be killed. By selecting a targeting domain that binds only to certain diseased cells (e.g., a cell which only expresses a cell surface receptor when in a diseased state), targeted toxins can kill the diseased cells while allowing healthy, essential cells to survive.

New Class of Immunotoxins with Extended Half-Life and High Anti-Tumor Activity

Recombinant immunotoxins (RITs) constitute a promising solution to hematologic cancers (e.g., Multiple Myeloma [MM]). RITs are chimeric proteins composed of a targeting domain fused to a bacterial toxin. Upon binding to a cancer cell displaying the target antigen, RITs are internalized, metabolized and the released toxin kills the cell. While highly active and effective, current RITs have short half-lives, requiring them to be used in high concentrations for treatment. At such high concentrations, RITs may show nonspecific activity and kill healthy cells.

A Target for the Development of Diagnostics and Therapeutics for Abnormal Hematopoiesis

The zinc finger protein ZFP36L2 has been shown by the inventors to play an essential role in hematopoiesis, a process that is dysregulated in hematological cancers, anemia, and other conditions. Thus, ZFP36L2 has promise for use in a diagnostic test to detect abnormal hematopoiesis, or as a target for the development of therapeutics to treat abnormal hematopoiesis.