Pharmacological inhibition of Carbonic Anhydrase IX and XII to enhance targeting of acute myeloid leukaemia cells under hypoxic conditions

Carbonic anhydrase IX: An atypical target for innovative therapies in cancer

Carbonic anhydrases (CAs), are metallo-enzymes implicated in several pathophysiological processes where tissue pH regulation is required. CA IX is a tumor-associated CA isoform induced by hypoxia and involved in the adaptation of tumor cells to acidosis. Indeed, several tumor-driving pathways can induce CA IX expression, and this in turn has been associated to cancer cells invasion and metastatic features as well as to induction of stem-like features, drug resistance and recurrence. After its functional and structural characterization CA IX targeting approaches have been developed to inhibit its activity in neoplastic tissues, and to date this field has seen an incredible acceleration in terms of therapeutic options and biological readouts. Small molecules inhibitors, hybrid/dual targeting drugs, targeting antibodies and adoptive (CAR-T based) cell therapy have been developed at preclinical level, whereas a sulfonamide CA IX inhibitor and an antibody entered Phase Ib/II clinical trials for the treatment and imaging of different solid tumors. Here recent advances on CA IX biology and pharmacology in cancer, and its therapeutic targeting will be discussed.

Exploring novel anticancer pyrazole benzenesulfonamides featuring tail approach strategy as carbonic anhydrase inhibitors

This study aimed to design potent carbonic anhydrase inhibitors (CAIs) based on pyrazole benzenesulfonamide core. Nine series of substituted pyrazole benzenesulfonamide compounds were synthesized with variable groups like sulphamoyl group as in compounds 4a-e, its bioisosteric carboxylic acid as in compounds 5a-e and 8e, ethyl carboxylate ester as in compounds 6a-e and 9a-e, which were designed as potential prodrugs, isothiazole ring as in compound 7, hydrazide derivative 10e, hydroxamic acid derivatives 11a-e and semicarbazide derivatives 12a-c,e. All the synthesized compounds were investigated for their carbonic anhydrase (CA) inhibitory activity against two human CA isoforms hCA IX and hCA XII and compared to acetazolamide (AAZ). Also, the compounds were assessed for their anticancer activity against 60 cancer cell lines according to the US NCI protocol. Compounds 4b, 5b, 5d, 5e, 6b, 9b, 9e and 11b revealed significant inhibitory activity against both isoforms hCA IX and hCA XII, while 6e, 9d, 11d and 11e showed significant inhibitory activity against hCA XII only compared to acetazolamide as a reference. This would highlight these compounds as promising anticancer drugs. Moreover, compound 6e revealed a remarkable cytostatic activity against CNS cancer cell line (SF-539; TGI = 5.58 μM), renal cancer cell line (786-0; TGI = 4.32 μM) and breast cancer cell line (HS 578 T; TGI = 5.43 μM). Accordingly, compound 6e was subjected to cell cycle analysis and apoptotic assay on the abovementioned cell lines at the specified GI50 (0.45, 0.89 and 1.18 μM, respectively). Also, it revealed the increment of total apoptotic cells percentage in 786-0 (53.19%), SF-539 (46.11%) and HS 578 T (43.55%) relative to the control cells (2.07, 2.64 and 2.52%, respectively). In silico prediction of BBB permeability showed that most of the calculations for compound 6e resulted as BBB (+), which is required for a compound targeting CNS. Further, the interaction of the most active compounds with the key amino acids in the active sites of hCA IX and hCA XII was highlighted by molecular docking analysis.

Targeting carbonic anhydrases for the management of hypoxic metastatic tumors

INTRODUCTION

Several isoforms of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) are connected with tumorigenesis. Hypoxic tumors overexpress CA IX and XII as a consequence of HIF activation cascade, being involved in pH regulation, metabolism, and metastases formation. Other isoforms (CA I, II, III, IV) were also reported to be present in some tumors.

AREAS COVERED

Some CA isoforms are biomarkers for disease progression or response to therapy. Inhibitors, antibodies, and other procedures for targeting these enzymes for the treatment of tumors/metastases are discussed. Sulfonamides and coumarins represent the most investigated classes of inhibitors, but carboxylates, selenium, and tellurium-containing inhibitors were also investigated. Hybrid drugs of CA inhibitors with other antitumor agents for multitargeted therapy were reported.

EXPERT OPINION

Targeting CAs present in solid or hematological tumors with selective, targeted inhibitors is a validated approach, which has been consolidated in the last years. A host of new preclinical data and several clinical trials of antibodies and small-molecule inhibitors are ongoing, which connected with the large number of new chemotypes/procedures discovered to be effective, may lead to a breakthrough in this therapeutic area. The scientific/patent literature has been searched for on PubMed, ScienceDirect, Espacenet, and PatentGuru, from 2018 to 2023.

2-Phenethylamines in Medicinal Chemistry: A Review

A concise review covering updated presence and role of 2-phenethylamines in medicinal chemistry is presented. Open-chain, flexible alicyclic amine derivatives of this motif are enumerated in key therapeutic targets, listing medicinal chemistry hits and appealing screening compounds. Latest reports in discovering new bioactive 2-phenethylamines by research groups are covered too.

The genesis and evolution of acute myeloid leukemia stem cells in the microenvironment: From biology to therapeutic targeting

Acute myeloid leukemia (AML) is a hematological malignancy characterized by cytogenetic and genomic alterations. Up to now, combination chemotherapy remains the standard treatment for leukemia. However, many individuals diagnosed with AML develop chemotherapeutic resistance and relapse. Recently, it has been pointed out that leukemic stem cells (LSCs) are the fundamental cause of drug resistance and AML relapse. LSCs only account for a small subpopulation of all leukemic cells, but possess stem cell properties, including a self-renewal capacity and a multi-directional differentiation potential. LSCs reside in a mostly quiescent state and are insensitive to chemotherapeutic agents. When LSCs reside in a bone marrow microenvironment (BMM) favorable to their survival, they engage into a steady, continuous clonal evolution to better adapt to the action of chemotherapy. Most chemotherapeutic drugs can only eliminate LSC-derived clones, reducing the number of leukemic cells in the BM to a normal range in order to achieve complete remission (CR). LSCs hidden in the BM niche can hardly be targeted or eradicated, leading to drug resistance and AML relapse. Understanding the relationship between LSCs, the BMM, and the generation and evolution laws of LSCs can facilitate the development of effective therapeutic targets and increase the efficiency of LSCs elimination in AML.

Cancer Therapeutic Targeting of Hypoxia Induced Carbonic Anhydrase IX: From Bench to Bedside

Simple Summary

Tumor hypoxia remains a significant problem in the effective treatment of most cancers. Tumor cells within hypoxic niches tend to be largely resistant to most therapeutic modalities, and adaptation of the cells within the hypoxic microenvironment imparts the cells with aggressive, invasive behavior. Thus, a major goal of successful cancer therapy should be the eradication of hypoxic tumor cells. Carbonic Anhydrase IX (CAIX) is an exquisitely hypoxia induced protein, selectively expressed on hypoxic tumor cells, and thus has garnered significant attention as a therapeutic target. In this Commentary, we discuss the current status of targeting CAIX, and future strategies for effective, durable cancer treatment.

Abstract

Carbonic Anhydrase IX (CAIX) is a major metabolic effector of tumor hypoxia and regulates intra- and extracellular pH and acidosis. Significant advances have been made recently in the development of therapeutic targeting of CAIX. These approaches include antibody-based immunotherapy, as well as use of antibodies to deliver toxic and radioactive payloads. In addition, a large number of small molecule inhibitors which inhibit the enzymatic activity of CAIX have been described. In this commentary, we highlight the current status of strategies targeting CAIX in both the pre-clinical and clinical space, and discuss future perspectives that leverage inhibition of CAIX in combination with additional targeted therapies to enable effective, durable approaches for cancer therapy.