Novel Anthraquinone-Based Benzenesulfonamide Derivatives and Their Analogues as Potent Human Carbonic Anhydrase Inhibitors with Antitumor Activity: Synthesis, Biological Evaluation, and In Silico Analysis.

In this study, we designed two series of novel anthraquinone-based benzenesulfonamide derivatives and their analogues as potential carbonic anhydrase inhibitors (CAIs) and evaluated their inhibitory activities against off-target human carbonic anhydrase II (hCA II) isoform and tumor-associated human carbonic anhydrase IX (hCA IX) isoform. Most of these compounds exhibited good inhibitory activities against hCA II and IX. The compounds that exhibited the best hCA inhibition were further studied against the MDA-MB-231, MCF-7, and HepG2 cell lines under hypoxic and normoxic conditions. Additionally, the compounds exhibiting the best antitumor activity were subjected to apoptosis and mitochondrial membrane potential assays, which revealed a significant increase in the percentage of apoptotic cells and a notable decrease in cell viability. Molecular docking studies were performed to demonstrate the presence of numerous hydrogen bonds and hydrophobic interactions between the compounds and the active site of hCA. Absorption, distribution, metabolism, excretion (ADME) predictions showed that all of the compounds had good pharmacokinetic and physicochemical properties.

A simple yet multifaceted 90 years old, evergreen enzyme: Carbonic anhydrase, its inhibition and activation.

Advances in the carbonic anhydrase (CA, EC 4.2.1.1) research over the last three decades are presented, with an emphasis on the deciphering of the activation mechanism, the development of isoform-selective inhibitors/ activators by the tail approach and their applications in the management of obesity, hypoxic tumors, neurological conditions, and as antiinfectives.

Discovery of new 6-ureido/amidocoumarins as highly potent and selective inhibitors for the tumour-relevant carbonic anhydrases IX and XII.

A series of 6-ureido/amidocoumarins (5a-p and 7a-c) has been designed and synthesised to develop potent and isoform- selective carbonic anhydrase hCA XI and XII inhibitors. All coumarin derivatives were investigated for their CA inhibitory effect against hCA I, II, IX, and XII. Interestingly, target coumarins potently inhibited both tumour-related isoforms hCA IX (KIs: 14.7-82.4 nM) and hCA XII (KIs: 5.9-95.1 nM), whereas the cytosolic off-target hCA I and II isoforms have not inhibited by all tested coumarins up to 100 µM. These findings granted the target coumarins an excellent selectivity profile towards both hCA IX and hCA XII isoforms, supporting their development as promising anticancer candidates. Moreover, all target molecules were evaluated for their anticancer activities against HCT-116 and MCF-7 cancer cells. The 3,5-bis-trifluoromethylphenyl ureidocoumarin 5i, exerted the best anticancer activity. Overall, ureidocoumarins, particularly compound 5i, could serve as a promising prototype for the development of potent anticancer CAIs.

Design and synthesis of some new benzoylthioureido benzenesulfonamide derivatives and their analogues as carbonic anhydrase inhibitors.

The present investigation reports the design and synthesis of three series of benzoylthioureido derivatives bearing either benzenesulfonamide 7a-f, benzoic acid 8a-f or ethylbenzoate 9a-f moieties. The synthesised compounds were screened for their carbonic anhydrase inhibitory activity (CAI) against four isoforms hCA I, II, IX, and XII. Compounds 7a, 7b, 7c, and 7f exhibited a potent inhibitory activity towards hCAI (Kis = 58.20, 56.30, 33.00, and 43.00 nM), respectively compared to acetazolamide (AAZ) and SLC-0111 (Kis = 250.00 and 5080.00 nM). Compounds 7a, 7b, 7c, 7e, and 7f elicited selectivity over h CA II (Kis = 2.50, 2.10, 56.60,39.60 and 39.00 nM) respectively, relative to AAZ and SLC-0111(Kis = 12.10 and 960.00 nM). Also, compounds 7c, 7f, and 9e displayed selectivity against the tumour-associated isoform hCA IX (Kis = 31.20, 30.00 and 29.00 nM) respectively, compared to AAZ and SLC-0111 (Kis = 25.70 and 45.00 nM). Additionally, compounds 8a and 8f revealed a moderate to superior selectivity towards hCAXII (Kis = 17.00 and 11.00 nM) relative to AAZ and SLC-0111(Kis = 5.70 and 45.00 nM). Molecular docking and ADME prediction studies were performed on the most active compounds to shed light on their interaction with the hot spots of the active site of CA isoforms, in addition to prediction of their pharmacokinetic and physicochemical properties.

Differential CMS-Related Expression of Cell Surface Carbonic Anhydrases IX and XII in Colorectal Cancer Models-Implications for Therapy.

Tumor-associated carbonic anhydrases IX (CAIX) and XII (CAXII) have long been in the spotlight as potential new targets for anti-cancer therapy. Recently, CAIX/CAXII specific inhibitor SLC-0111 has passed clinical phase I study and showed differential response among patients with colorectal cancer (CRC). CRC can be classified into four different consensus molecular subgroups (CMS) showing unique expression patterns and molecular traits. We questioned whether there is a CMS-related CAIX/CAXII expression pattern in CRC predicting response. As such, we analyzed transcriptomic data of tumor samples for CA9/CA12 expression using Cancertool. Protein expression pattern was examined in preclinical models comprising cell lines, spheroids and xenograft tumors representing the CMS groups. Impact of CAIX/CAXII knockdown and SLC-0111 treatment was investigated in 2D and 3D cell culture. The transcriptomic data revealed a characteristic CMS-related CA9/CA12 expression pattern with pronounced co-expression of both CAs as a typical feature of CMS3 tumors. Protein expression in spheroid- and xenograft tumor tissue clearly differed, ranging from close to none (CMS1) to strong CAIX/CAXII co-expression in CMS3 models (HT29, LS174T). Accordingly, response to SLC-0111 analyzed in the spheroid model ranged from no (CMS1) to clear (CMS3), with moderate in CMS2 and mixed in CMS4. Furthermore, SLC-0111 positively affected impact of single and combined chemotherapeutic treatment of CMS3 spheroids. In addition, combined CAIX/CAXII knockdown and more effective treatment with SLC-0111 reduced clonogenic survival of CMS3 modelling single cells. In conclusion, the preclinical data support the clinical approach of targeted CAIX/CAXII inhibition by showing linkage of expression with response and suggest that patients with CMS3-classified tumors would most benefit from such treatment.

A decade of tail-approach based design of selective as well as potent tumor associated carbonic anhydrase inhibitors.

Human carbonic anhydrase (hCA) isoforms hCA IX and hCA XII are well established anticancer drug targets and their selective inhibition is highly desired for the proper treatment of cancer. Lack of isoform-selectivity in current clinically used CA inhibitors (CAIs) is a major concern as it leads to undesired side effects, associated with off-target inhibition. Thus, there is need to explore alternative approaches for the design of isoform-selective inhibitors and the leading promising approach for the design of isoform-selective CAIs is "the tail-approach". Virtually, most drug design studies in the last decade were done by considering the tail-approach reported in 1999. The past decade of 2010-2020 witnessed progressive maturation of this approach as a large number of CAIs have been designed and synthesised based on it, many of which turned out to be effective as well as selective hCA IX and hCA XII inhibitors. This review covers the past decade (2010-2020) research, considering selective as well as potent inhibitors of tumor associated isoforms, hCA IX and hCA XII, which include newer generation inhibitors containing sulfonamides or their bioisosteres, non-classical inhibitors (including carboxylic acid/ester, coumarin and sulfocoumarin classes) and various other novel classes of inhibitors belonging to newly identified chemotypes/scaffolds.

Tail-approach based design and synthesis of Arylthiazolylhydrazono-1,2,3-triazoles incorporating sulfanilamide and metanilamide as human carbonic anhydrase I, II, IV and IX inhibitors.

A library of twenty-two arylthiazolylhydrazono-1,2,3-triazoles incorporating sulfanilamide and metanilamide moieties have been synthesized by utilizing tail-approach and characterized by their IR, 1H NMR, 13C NMR, HRMS and single crystal studies. Further, these newly synthesized compounds were screened in-vitro for their inhibition efficacy against physiologically relevant hCA I, II, IV and IX isoforms. Inhibition data revealed that, in broader sense, sulfanilamide analogues (4a-4k) were comparatively better inhibitors of cytosolic hCA I and II isoforms than metanilamide analogues (5a-5k), whereas exactly opposite trend was observed in case of inhibition of membrane bound hCA IV and transmembrane hCA IX. For hCA I, more than half of the synthesized compounds were found to be moderate inhibitors and three compounds 4b, 5b and 5e (Ki of 40.6, 224.7 and 74.4 nM, respectively) appeared as better inhibitors than reference drug AAZ (Ki = 250 nM). hCA II was potently inhibited by 4e-4g and 5e with Ki of 18.1, 14.1, 14.9 and 17.8 nM, respectively. Interestingly, 4e-4g selectively inhibited hCA II with selectivity of > 15-fold over hCA I, IV and IX isoforms. All the compounds presented moderate to weak inhibition profiles against glaucoma associated hCA IV with Ki of 88 nM-8.87 µM and except 4f, 5k, significant inhibition profiles against tumor associated hCA IX isoform with Ki spanning in range of 0.113 µM-0.318 µM. Moreover, 5e was the only compound among the whole series which effectively inhibited all the tested isoforms.

Design and synthesis of some new benzoylthioureido phenyl derivatives targeting carbonic anhydrase enzymes.

The present study aimed to develop potent carbonic anhydrase inhibitors (CAIs). The design of the target compounds was based on modifying the structure of the ureido-based carbonic anhydrase inhibitor SLC-0111. Six series of a substituted benzoylthioureido core were prepared featuring different zinc-binding groups; the conventional sulphamoyl group 4a-d and 12a-c, its bioisosteric carboxylic acid group 5a-d and 13a-c or the ethyl carboxylate group 6a-d and 14a-c as potential prodrugs. All compounds were assessed for their carbonic anhydrase (CA) inhibitory activity against a panel of four physiologically relevant human CA isoforms hCA I and hCA II, and hCA IX, and hCA XII. Compounds 4a, 4b, 4c, 4d, 5d, 12a, and 12c revealed significant inhibitory activity against hCA I that would highlight these compounds as promising drug candidates for the treatment of glaucoma.

Antiproliferative effects of sulphonamide carbonic anhydrase inhibitors C18, SLC-0111 and acetazolamide on bladder, glioblastoma and pancreatic cancer cell lines.

Carbonic anhydrase IX/XII (CA IX/XII), are cell-surface enzymes typically expressed by cancer cells as a form of adaptation to hypoxia and acidosis. It has been widely reported that these proteins play pivotal roles in cancer progression fostering cell migration, aggressiveness and resistance to first line chemo- and radiotherapies. CA IX has emerged as a promising target in cancer therapy and several approaches and families of compounds were characterised in the attempt to find optimal targeting by inhibiting of the high catalytic activity of the enzyme. In the present work, different cell lines representing glioblastoma, bladder and pancreatic cancer have been exploited to compare the inhibitory and antiproliferative effect of primary sulphonamide acetazolamide (AAZ), the Phase Ib/II clinical grade sulphonamide SLC-0111, and a membrane-impermeant positively charged, pyridinium-derivative (C18). New hints regarding the possibility to exploit CA inhibitors in these cancer types are proposed.

Perfusion-Based Bioreactor Culture and Isothermal Microcalorimetry for Preclinical Drug Testing with the Carbonic Anhydrase Inhibitor SLC-0111 in Patient-Derived Neuroblastoma.

Neuroblastoma is a rare disease. Rare are also the possibilities to test new therapeutic options for neuroblastoma in clinical trials. Despite the constant need to improve therapy and outcomes for patients with advanced neuroblastoma, clinical trials currently only allow for testing few substances in even fewer patients. This increases the need to improve and advance preclinical models for neuroblastoma to preselect favorable candidates for novel therapeutics. Here we propose the use of a new patient-derived 3D slice-culture perfusion-based 3D model in combination with rapid treatment evaluation using isothermal microcalorimetry exemplified with treatment with the novel carbonic anhydrase IX and XII (CAIX/CAXII) inhibitor SLC-0111. Patient samples showed a CAIX expression of 18% and a CAXII expression of 30%. Corresponding with their respective CAIX expression patterns, the viability of SH-EP cells was significantly reduced upon treatment with SLC-0111, while LAN1 cells were not affected. The inhibitory effect on SH-SY5Y cells was dependent on the induction of CAIX expression under hypoxia. These findings corresponded to thermogenesis of the cells. Patient-derived organotypic slice cultures were treated with SLC-0111, which was highly effective despite heterogeneity of CAIX/CAXII expression. Thermogenesis, in congruence with the findings of the histological observations, was significantly reduced in SLC-0111-treated samples. In order to extend the evaluation time, we established a perfusion-based approach for neuroblastoma tissue in a 3D perfusion-based bioreactor system. Using this system, excellent tissue quality with intact tumor cells and stromal structure in neuroblastoma tumors can be maintained for 7 days. The system was successfully used for consecutive drug response monitoring with isothermal microcalorimetry. The described approach for drug testing, relying on an advanced 3D culture system combined with a rapid and highly sensitive metabolic assessment, can facilitate development of personalized treatment strategies for neuroblastoma.

Progress in the development of human carbonic anhydrase inhibitors and their pharmacological applications: Where are we today?

Carbonic anhydrases (CAs, EC 4.2.1.1) are widely distributed metalloenzymes in both prokaryotes and eukaryotes. They efficiently catalyze the reversible hydration of carbon dioxide to bicarbonate and H+  ions and play a crucial role in regulating many physiological processes. CAs are well-studied drug target for various disorders such as glaucoma, epilepsy, sleep apnea, and high altitude sickness. In the past decades, a large category of diverse families of CA inhibitors (CAIs) have been developed and many of them showed effective inhibition toward specific isoforms, and effectiveness in pathological conditions in preclinical and clinical settings. The discovery of isoform-selective CAIs in the last decade led to diminished side effects associated with off-target isoforms inhibition. The many new classes of such compounds will be discussed in the review, together with strategies for their development. Pharmacological advances of the newly emerged CAIs in diseases not usually associated with CA inhibition (neuropathic pain, arthritis, cerebral ischemia, and cancer) will also be discussed.

The Carbonic Anhydrase IX inhibitor SLC-0111 as emerging agent against the mesenchymal stem cell-derived pro-survival effects on melanoma cells.

Mesenchymal stem cells (MSC) take part to solid tumour-associated stroma and critically influence progression of malignancy. Our study represents a striking example of melanoma progression to a more malignant and resistant phenotype promoted by MSC and the possibility to contrast this diabolic liaison using CAIX inhibitors. In particular, we demonstrated that melanoma cells exposed to a MSC-conditioned medium switch to a more malignant phenotype, characterised by resistance to programmed cell death and endowed with an epithelial-to-mesenchymal transition and stem cell characteristics. These effects were reversed abrogating MSC CAIX activity using SLC-0111, a CAIX inhibitor. Moreover, the acquisition by melanoma cells of a Vemurafenib-resistant phenotype upon MSC-conditioned medium exposure was removed when MSC were treated with SLC-0111. Therefore, MSC may profoundly reprogramme melanoma cells towards a wide resistant phenotype through CAIX involvement, as the use of SLC-0111 is able to contrast the development of this highly risky adaptation for disease progression.

A potentiated cooperation of carbonic anhydrase IX and histone deacetylase inhibitors against cancer.

The emergence of tumour recurrence and resistance limits the survival rate for most tumour-bearing patients. Only, combination therapies targeting pathways involved in the induction and in the maintenance of cancer growth and progression might potentially result in an enhanced therapeutic efficacy. Herein, we provided a prospective combination treatment that includes suberoylanilide hydroxamic acid (SAHA), a well-known inhibitor of histone deacetylases (HDACs), and SLC-0111, a novel inhibitor of carbonic anhydrase (CA) IX. We proved that HDAC inhibition with SAHA in combination with SLC-0111 affects cell viability and colony forming capability to greater extent than either treatment alone of breast, colorectal and melanoma cancer cells. At the molecular level, this therapeutic regimen resulted in a synergistically increase of histone H4 and p53 acetylation in all tested cell lines. Overall, our findings showed that SAHA and SLC-0111 can be regarded as very attractive combination providing a potential therapeutic strategy against different cancer models.

Extrinsic acidosis suppresses glycolysis and migration while increasing network formation in pulmonary microvascular endothelial cells.

Acidosis is common among critically ill patients, but current approaches to correct pH do not improve disease outcomes. During systemic acidosis, cells are either passively exposed to extracellular acidosis that other cells have generated (extrinsic acidosis) or they are exposed to acid that they generate and export into the extracellular space (intrinsic acidosis). Although endothelial repair following intrinsic acidosis has been studied, the impact of extrinsic acidosis on migration and angiogenesis is unclear. We hypothesized that extrinsic acidosis inhibits metabolism and migration but promotes capillary-like network formation in pulmonary microvascular endothelial cells (PMVECs). Extrinsic acidosis was modeled by titrating media pH. Two types of intrinsic acidosis were compared, including increasing cellular metabolism by chemically inhibiting carbonic anhydrases (CAs) IX and XII (SLC-0111) and with hypoxia. PMVECs maintained baseline intracellular pH for 24 h with both extrinsic and intrinsic acidosis. Whole cell CA IX protein expression was decreased by extrinsic acidosis but not affected by hypoxia. When extracellular pH was equally acidic, extrinsic acidosis suppressed glycolysis, whereas intrinsic acidosis did not. Extrinsic acidosis suppressed migration, but increased Matrigel network master junction and total segment length. CRISPR-Cas9 CA IX knockout PMVECs revealed an independent role of CA IX in promoting glycolysis, as loss of CA IX alone was accompanied by decreased hexokinase I and pyruvate dehydrogenase E1α expression and decreasing migration. 2-deoxy-d-glucose had no effect on migration but profoundly inhibited network formation and increased N-cadherin expression. Thus, we report that while extrinsic acidosis suppresses endothelial glycolysis and migration, it promotes network formation.

SLC-0111 enaminone analogs, 3/4-(3-aryl-3-oxopropenyl) aminobenzenesulfonamides, as novel selective subnanomolar inhibitors of the tumor-associated carbonic anhydrase isoform IX.

SLC-0111, an ureido substituted benzenesulfonamide, is a selective carbonic anhydrase (CA, EC 4.2.1.1) IX inhibitor that is currently in Phase I/II clinical trials for the treatment of advanced hypoxic tumors complicated with metastases. Herein we report the synthesis of two series of 3/4-(3-aryl-3-oxopropenyl) aminobenzenesulfonamides 5a-i and 6a-j as SLC-0111 enaminone congeners. The prepared enaminones were in vitro investigated as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) isoforms hCA I, II, IV and IX, using a stopped-flow CO2 hydrase assay. All these isoforms were inhibited by the enaminones reported here in variable degrees. The target tumor-associated isoform hCA IX was undeniably the most affected one (KIs: 0.21-7.1 nM), with 6- to 21-fold enhanced activity than SLC-0111 (KI = 45 nM). All the prepared enaminones displayed interesting selectivity towards hCA IX over hCA I (SI: 32 - >35714), hCA II (SI: 2 - 1689) and hCA IV (SI: 11 - >45454). Of particular interest, bioisosteric replacement of phenyl tail with the bulkier 2-naphthyl tail, sulfonamide 6h, achieved the higher II/IX selectivity herein reported with SI of 1689.

Novel synthesized SLC-0111 thiazole and thiadiazole analogues: Determination of their carbonic anhydrase inhibitory activity and molecular modeling studies.

In the presented work, we report the design and synthesis of novel SLC-0111 thiazole and thiadiazole analogues (11a-d, 12a-d, 16a-c and 17a-d). A bioisosteric replacement approach was adopted to replace the 4-fluorophenyl tail of SLC-0111 with thiazole and thiadiazole ones, which were thereafter extended with lipophilic un/substituted phenyl moieties. All the newly synthesized SLC-0111 analogues were evaluated in vitro for their inhibitory activity towards a panel of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) isoforms (hCA I, II, IX and XII), using a stopped-flow CO2 hydrase assay. All the examined isoforms were inhibited by the primary sulfonamide derivatives (11a-d and 12a-d) in variable degrees with the following KI ranges: 162.6-7136 nM for hCA I, 9.0-833.6 nM for hCA II, 7.9-153.0 nM for hCA IX, and 9.4-94.0 nM for hCA XII. In particular, compounds 12b and 12d displayed 5.5-fold more potent inhibitory activity (KIs = 8.3 and 7.9 nM, respectively) than SLC-0111 (KI = 45 nM) towards hCA IX. Molecular docking study was carried out for 12d within the hCA IX (PDB 3IAI) active site, to justify its inhibitory activity.

The carbonic anhydrase IX inhibitor SLC-0111 sensitises cancer cells to conventional chemotherapy.

Drug combination represents one of the most accredited strategies of cancer therapy able to improve drug efficacy and possibly overcome drug resistance. Among the agents used to complement conventional chemotherapy, carbonic anhydrase IX (CAIX) inhibitors appear as one of the most suitable, as markers of hypoxic and acidic cancer cells which do not respond to chemo- and radiotherapy. We performed preclinical in vitro assays to evaluate whether the SLC-0111 CAIX inhibitor co-operates and potentiates the cytotoxic effects of conventional chemotherapeutic drugs in A375-M6 melanoma cells, MCF7 breast cancer cells, and HCT116 colorectal cancer cells. Here, we demonstrate that the SLC-0111 CAIX inhibitor potentiates cytotoxicity of Dacarbazine and Temozolomide currently used for advanced melanoma treatment. SLC-0111 also increases breast cancer cell response to Doxorubicin and enhances 5-Fluorouracil cytostatic activity on colon cancer cells. These findings disclose the possibility to extend the use of CAIX inhibitors in the combination therapy of various cancer histotypes.

Preclinical Evaluation of Ureidosulfamate Carbonic Anhydrase IX/XII Inhibitors in the Treatment of Cancers.

Carbonic anhydrases (CAs) are a family of enzymes involved in the pH regulation of metabolically active cells/tissues. Upregulation of the CAIX/XII isoforms is associated with hypoxic tumours and clinically linked with malignant progression, treatment resistance and poor prognosis. The elucidation of the crystal structure of the catalytic domains of CAIX/XII provided the basis for the generation of CAIX/XII selective inhibitors based on the sulfonamide, sulfamate and coumarins chemical structures. Ureido-substituted benzenesulfonamide CAIX/XII inhibitors have shown significant potential, with U-104 (SLC-0111) currently present in clinical Phase I/II. Ureido-substituted sulfamate CAIX/XII inhibitors have received less attention despite encouraging preclinical test results. In triple-negative breast cancer (TNBC), ureidosulfamates revealed a significant antitumour (FC9-398A) and antimetastatic potential (S4). In small cell lung cancer (SCLC), a cancer cell type very sensitive to a dysregulation in CAIX signaling, S4 treatment was particularly effective when combined with cisplatin with no evidence of acquired cisplatin-resistance. These successful anticancer strategies should provide a solid basis for future studies on ureido-substituted sulfamates.

Carbonic anhydrase IX is a critical determinant of pulmonary microvascular endothelial cell pH regulation and angiogenesis during acidosis.

Carbonic anhydrase IX (CA IX) is highly expressed in rapidly proliferating and highly glycolytic cells, where it serves to enhance acid-regulatory capacity. Pulmonary microvascular endothelial cells (PMVECs) actively utilize aerobic glycolysis and acidify media, whereas pulmonary arterial endothelial cells (PAECs) primarily rely on oxidative phosphorylation and minimally change media pH. Therefore, we hypothesized that CA IX is critical to PMVEC angiogenesis because of its important role in regulating pH. To test this hypothesis, PMVECs and PAECs were isolated from Sprague-Dawley rats. CA IX knockout PMVECs were generated using the CRISPR-Cas9 technique. During serum-stimulated growth, mild acidosis (pH 6.8) did not affect cell counts of PMVECs, but it decreased PAEC cell number. Severe acidosis (pH 6.2) decreased cell counts of PMVECs and elicited an even more pronounced reduction of PAECs. PMVECs had a higher CA IX expression compared with PAECs. CA activity was higher in PMVECs compared with PAECs, and enzyme activity was dependent on the type IX isoform. Pharmacological inhibition and genetic ablation of CA IX caused profound dysregulation of extra- and intracellular pH in PMVECs. Matrigel assays revealed impaired angiogenesis of CA IX knockout PMVECs in acidosis. Lastly, pharmacological CA IX inhibition caused profound cell death in PMVECs, whereas genetic CA IX ablation had little effect on PMVEC cell death in acidosis. Thus CA IX controls PMVEC pH necessary for angiogenesis during acidosis. CA IX may contribute to lung vascular repair during acute lung injury that is accompanied by acidosis within the microenvironment.

Synthesis and carbonic anhydrase inhibition of a series of SLC-0111 analogs.

SLC-0111 is a sulfonamide carbonic anhydrase (CA, EC 4.2.1.1) inhibitor (CAI) in Phase I/II clinical trials for the treatment of advanced hypoxic tumors complicated with metastases. Its antitumor effects are due to inhibition of the enzymatic activity of CA IX, an isoform predominantly found in tumors/metastases, but it also reduces the cancer stem cells population. Here we report the synthesis of analogs of SLC-0111, both of the sulfanilamide and metanilamide series, which possess diverse substitution patterns at the terminal ureido-phenyl moiety, thus including one or more halogens, trifluoromethyl, perchloro-/perfluorophenyl groups instead of the 4-fluorophenyl present in SLC-0111. Most of the sulfanilamide ureido derivatives were highly effective inhibitors of the tumor associated isoform and some showed selective CA IX/XII inhibitory profiles. Most of the sulfanilamide ureido derivatives were highly effective and in some cases selective CA IX/XII inhibitors, whereas the metanilamide ureido derivatives were less effective as transmembrane CA isoforms inhibitors. Structure activity relationship for this class of sulfonamides is discussed in detail.