Carbonic Anhydrase IX as an Anticancer Therapy Target: Preclinical Evaluation of Internalizing Monoclonal Antibody Directed to Catalytic Domain

Abstract

Carbonic anhydrase IX (CA IX) is a suitable target for various anticancer strategies. It is a cell surface protein that is present in human tumors, but not in the corresponding normal tissues. Expression of CA IX is induced by hypoxia and correlates with cancer prognosis in many tumor types. Moreover, CA IX is functionally implicated in cancer progression as a pro-survival factor protecting cancer cells against hypoxia and acidosis via its capability to regulate pH and cell adhesion. Cancer-related distribution of CA IX allows for targeting cancer cells by antibodies binding to its extracellular domain, whereas functional involvement of CA IX opens the possibility to hit cancer cells by blocking their adaptation to physiologic stresses via inhibition of CA IX enzyme activity. The latter strategy is recently receiving considerable attention and great efforts are made to produce CA IX-selective inhibitor derivatives with anticancer effects. On the other hand, targeting CA IX-expressing cells by immunotherapy has reached clinical trials and is close to application in treatment of renal cell carcinoma patients. Nevertheless, development and characterization of new CA IX-specific antibodies is still ongoing. Here we describe a mouse monoclonal antibody VII/20 directed to catalytic domain of CA IX. We show that upon binding to CA IX, the VII/20 MAb undergoes efficient receptor-mediated internalization, which is a process regulating abundance and signaling of cell surface proteins and has considerable impact on immunotherapy. We evaluated biological properties of the MAb and demonstrated its capacity to elicit anti-cancer effect in mouse xenograft model of colorectal carcinoma. Thus, the VII/20 MAb might serve as a tool for preclinical studies of immunotherapeutic strategies against non-RCC tumors. These have not been explored so far and include broad spectrum of cancer types, treatment of which might benefit from CA IX-mediated targeting.

Encapsulation of anti-carbonic anhydrase IX antibody in hydrogel microspheres for tumor targeting

“…These data clearly reveal that there is no obvious difference in the M75 reactivity after encapsulation into either SA-beads or PMCG microcapsules, suggesting that the encapsulation procedure did not affect the integrity of the antibody 17 .…”

“…Numerous studies have supported its promising position as one of the most prominent markers of tumor hypoxia with the predictive and prognostic values. As CA IX functions as a highly active enzyme with the catalytic domain exposed on the outer side of the plasma membrane, it can be efficiently targeted by CA IX-inhibitors (sulfonamides, their derivatives and related compounds) or antibodies 16,17 . In summary, the expression pattern of CA IX is tightly associated with a broad variety of human tumors, while it is significantly expressed in only few normal tissues.…”

Novel approaches to antiviral and anticancer immunotherapy

“…The cancer model we use is a tumor-associated cell-surface carbonic anhydrase IX (CA IX), (Fig. 1) which is currently evaluated as a marker of tumor hypoxia and therapeutic target in pre-clinical experiments as well as in MAb immunotherapy-based clinical trials (Zatovicova et al, 2010;Reichert, 2011). CA IX belongs to the family of carbonic anhydrases that participate in physiological processes based on pH balance and ion transport.…”

Targeting Tumor Microenvironments for Cancer Prevention and Therapy

“…CAIX small molecule inhibitors and antibodies have been developed and evaluated as potential anti-cancer therapeutics. A CAIX monoclonal antibody exhibited anti-tumor activities in the mouse xenograft model of colorectal cancer (Zatovicova et al, 2010). Moreover, CAIX inhibitors were shown to increase the therapeutic effects of tumor radiation (Dubois et al, 2011).…”