Altumomab is a recombinant mouse antibody to carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), also known as CD66e (cluster of differentiation 66e), which is a member of the carcinoembryonic antigen (CEA) gene family. Indium (111In) altumomab pentetate (INN) (USP, indium In111 altumomab pentetate; trade name Hybri-ceaker) is a mouse monoclonal antibody linked to pentetate which acts as a chelating agent for the radioisotope indium-111. The drug is used for the diagnosis of colorectal cancer.
Tumor cells disseminate early in tumor development making metastasis-prevention strategies difficult. Identifying proteins that promote the outgrowth of disseminated tumor cells may provide opportunities for novel therapeutic strategies. Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) was identified as a metastatic driver. CEACAM5 overproduction enriched for an epithelial gene expression pattern and facilitated tumor outgrowth at metastatic sites. Tissues from patients with metastatic breast cancer confirmed elevated levels of CEACAM5 in lung metastases relative to breast tumors, and an inverse correlation between CEACAM5 and the mesenchymal marker vimentin was demonstrated. Thus, CEACAM5 facilitates tumor outgrowth at metastatic sites by promoting MET, warranting its investigation as a therapeutic target and biomarker of aggressiveness in breast cancer. altumomab has been labeled with indium-111. For tumors that overexpress CEACAM5, altumomab may be used as an adjunct diagnostic imaging tool to obtain prognostic information and to monitor for cancer. Consequently, the antibody accumulates in tumors together with the radioisotope, which emits photons. Via single photon emission computed tomography (SPECT), high-resolution images showing localization, remission or progression, and metastases of the tumour can be obtained.
Fig 1. Mechanism of Action of Altumomab