Clone KK3 validated for studying the CD73-adenosine checkpoint in FFPE tissues
Fig.01 Strong homogeneous CD73 (clone KK3) immunostaining in a cholangiocellular carcinoma of the liver.
Fig.02 Membranous CD73 positivity in a hepatocellular carcinoma of the liver shows a heterogeneous pattern (clone KK3).
Fig.03 Prominent membranous CD73 positivity in a malignant melanoma with clone KK3.
Fig.04 Membranous CD73 immunostaining (clone KK73) in an adenocarcinoma of the lung shows apical predominance.
Fig.05 Strong diffuse CD73 positivity in a squamous cell carcinoma of the lung (clone KK3).
Fig.06 CD73 clone KK3 immunohistochemistry in a mixed tumor of the lung.
Fig.07 CD73 clone KK3 immunohistochemistry in tonsil.
Fig.08 Strong membranous CD73 expression in an angiosarcoma (imunohistochemistry with clone KK3).
Fig.09 Strong CD73 positivity of the superficial membrane of the placenta syncytiotrophoblast (clone KK3).
Fig.10 A Whartin tumor of the parotis shows distinct CD73 staining in lymphocytes (clone KK3).

CD73 and CD39 are cell surface enzymes that catabolize the breakdown of extracellular ATP into adenosine. As ectonucleosidases they play important roles in maintaining tissue and immune homeostasis through interfering with the extracellular purigeneric pathway. Since several labs independently have demonstrated an immunosuppressive role of CD73-adenosine in cancer, the CD73-adenosine axis has emerged as one of the most promising therapeutic targets in immuno-oncology.

Adenosine triphosphate (ATP) is the major source of energy for the cell. Malignant cells can release high levels of ATP (e.g. after damage by radiotherapy or chemotherapy). Extracellular ATP provokes inflammation by driving “purinergic signals” and plays a significant role in promoting anti-tumor responses. Many tumors express the ectonucleotidases CD39 and CD73 to scarve such proinflammatory mediators and generate immunosuppressive adenosine nucleosides.

Clone KK3 has been developed and validated specifically for the immunohistochemical (IHC) detection of CD73 in routine FFPE human tissue specimen. Given the broad expression of ectonucleotidases and adenosine receptors, immunohistochemical (IHC) application of monoclonal antibody KK3 may help to develop a better understanding of cell- and tissue- specific roles. Moreover, besides elucidation of the mechanisms-of-action of CD73 and adenosine-targeting agents it is important to differentiate patient populations.  Immunohistochemical (IHC) application of anti-CD73 clone KK3 may provide valuable information for identification of patients that will benefit from novel therapies.

CD73 Antibody Productdetails