New approach of delivering cytotoxic drugs towards CAIX expressing cells : A concept of dual-target drugs

Abstract Carbonic anhydrase IX (CAIX) is a hypoxia-regulated and tumor-specific protein that maintains the pH balance of cells. Targeting CAIX might be a valuable approach for specific delivery of cytotoxic drugs, thereby reducing normal tissue side-effects. A series of dual-target compounds were designed and synthesized incorporating a sulfonamide, sulfamide, or sulfamate moiety combined with several different anti-cancer drugs, including the chemotherapeutic agents chlorambucil, tirapazamine, and temozolomide, two Ataxia Telangiectasia and Rad3-related protein inhibitors (ATRi), and the anti-diabetic biguanide agent phenformin. An ATRi derivative (12) was the only compound to show a preferred efficacy in CAIX overexpressing cells versus cells without CAIX expression when combined with radiation. Its efficacy might however not solely depend on binding to CAIX, since all described compounds generally display low activity as carbonic anhydrase inhibitors. The hypothesis that dual-target compounds specifically target CAIX expressing tumor cells was therefore not confirmed. Even though dual-target compounds remain an interesting approach, alternative options should also be investigated as novel treatment strategies

Targeting carbonic anhydrase IX by nitroimidazole based sulfamides enhances the therapeutic effect of tumor irradiation: A new concept of dual targeting drugs

n/

The sulfamate small molecule CAIX inhibitor 1 S4 modulates 2 doxorubicin efficacy

Carbonic anhydrase IX (CAIX) is a tumor-specific protein that is upregulated during hypoxic conditions where it is involved in maintaining the pH balance. CAIX causes extracellular acidification, thereby limiting the uptake of weak basic chemotherapeutic agents, such as doxorubicin, and decreasing its efficacy. The aim of this study was to determine if doxorubicin efficacy can be increased when combined with the selective sulfamate CAIX inhibitor S4. The effect of S4 on doxorubicin efficacy was tested in vitro using cell viability assays with MDA-MB-231, FaDu, HT29 -CAIX high and HT29 -CAIX low cell lines. In addition, the efficacy of this combination therapy was investigated in tumor xenografts of the same cell lines. The addition of S4 in vitro increased the efficacy of doxorubicin in the MDA-MB-231 during hypoxic exposure (IC50 is 0.25 versus 0.14 µM, p = 0.0003). Similar results were observed for HT29-CAIX high with S4 during normoxia (IC50 is 0.20 versus 0.08 µM, p<0.0001) and in the HT29 -CAIX low cells (IC50 is 0.09 µM, p<0.0001). In vivo doxorubicin treatment was only effective in the MDA-MB-231 xenografts, but the efficacy of doxorubicin was decreased when combined with S4. In conclusion, the efficacy of doxorubicin treatment can be increased when combined with the selective sulfamate CAIX inhibitor S4 in vitro in certain cell lines. Nevertheless, in xenografts S4 did not enhance doxorubicin efficacy in the FaDu and HT29 tumor models and decreased doxorubicin efficacy in the MDA-MB-231 tumor model. These results stress the importance of better understanding the role of CAIX inhibitors in intratumoral pH regulation before combining them with standard treatment modalities, such as doxorubicin

New ways to image and target tumour hypoxia and its molecular responses

International audienceTumour hypoxia and its molecular responses have been shown to be associated with poor prognosis. Detection of hypoxia, preferably in a non-invasive manner, could therefore predict treatment outcome and serve as a tool to individualize treatment. This review gives an overview of recent literature on hypoxia imaging markers currently used in clinical trials. Furthermore, recent progress made in targeting hypoxia (hypoxia-activated prodrugs) or hypoxia response (carbonic anhydrase IX inhibitors) is summarized. Last, window-of-opportunity trials implementing non-invasive imaging are proposed as an important tool to prove anti-tumour efficacy of experimental drugs early during drug development

Constitutive expression of gamma-H2AX has prognostic relevance in triple negative breast cancer

Contains fulltext : 97756.pdf (publisher's version ) (Closed access)BACKGROUND AND PURPOSE: Constitutive gamma-H2AX expression might indicate disruption of the DNA damage repair pathway, genomic instability, or shortened telomeric ends. Here, we quantified expression of endogenous gamma-H2AX and its downstream factor 53BP1 in a large number of breast cancer cell lines (n=54) and a node-negative breast cancer cohort that had not received adjuvant systemic treatment (n=122). MATERIALS AND METHODS: Formalin fixed paraffin embedded breast cancer cell lines and tumors were immunohistochemically analyzed for gamma-H2AX and 53BP1 expression, and related to cell line, patient and tumor characteristics and to disease progression. RESULTS: In breast cancer cell lines, gamma-H2AX positivity was associated with the triple negative/basal like subgroup (p=0.005), and with BRCA1 (p=0.011) or p53 (p=0.053) mutations. Specifically in triple negative breast cancer patients a high number of gamma-H2AX foci indicated a significantly worse prognosis (p=0.006 for triple negative vs. p=0.417 for estrogen receptor (ER), progesterone receptor (PR) or HER2 positive patients). A similar association with disease progression was found for 53BP1. In a multivariate analysis with tumor size, grade, and triple negativity, only the interaction between triple negativity and gamma-H2AX remained significant (p=0.002, Hazard Ratio=6.77, 95% CI=2.07-22.2). CONCLUSIONS: Constitutive gamma-H2AX and 53BP1 staining reveals a subset of patients with triple negative breast tumors that have a significantly poorer prognosis