Discovery of 4-Hydroxy-3-(3-(phenylureido)benzenesulfonamides as SLC-0111 Analogues for the Treatment of Hypoxic Tumors Overexpressing Carbonic Anhydrase IX

Herein we report the 2-aminophenol-4-sulfonamide 1 and its ureido derivatives 2-23 as inhibitors of the carbonic anhydrase (CA, EC 4.2.1.1) enzymes as analogues of the hypoxic tumor phase II entering drug SLC-0111. This scaffold may determine preferential rotational isomers to selectively interact within the tumor-associated CAs. Most of the compounds indeed showed in vitro selective inhibition of the tumor associated CA isoforms IX and XII. The most potent derivative within the series was 11 ( K_Is of 2.59 and 7.64 nM on hCA IX and XII, respectively), which shares the 4-fluorophenylureido tail with the clinical candidate. We investigated by means of X-ray crystallographic studies the binding modes of three selected compounds of this series to CA I. The evaluation of therapeutic efficacy of compound 11 in an orthotopic, syngeneic model of CA IX-positive breast cancer in vivo showed close matching antitumoral effects and tolerance with SLC-0111.

Abstract 2941: APE1/Ref-1 redox signaling regulates HIF1a-mediated CA9 expression in hypoxic pancreatic cancer cells: Combination treatment in patient-derived pancreatic tumor models

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease characterized by aggressive metastasis and therapeutic resistance. Reactive stroma in PDAC tumors leads to fibrosis, inflammation, and hypoxia. Hypoxia signaling creates a more aggressive phenotype with increased potential for metastasis and decreased therapeutic efficacy. Carbonic anhydrase IX (CA9) functions as part of the cellular response to hypoxia by regulating intracellular pH to promote cell survival. Apurinic/Apyrimidinic Endonuclease-1-Reduction/oxidation Effector Factor 1 (APE1/Ref-1) is a multifunctional protein with endonuclease activity in DNA base excision repair and redox signaling activity. This redox activity is responsible for reducing oxidized cysteines on specific transcription factors, including hypoxia inducible factor 1 alpha (HIF1α), enabling them to bind target sequences in DNA. We evaluated the mechanisms underlying PDAC cell responses to hypoxia and APE1/Ref-1 redox signaling control of HIF1α, a critical factor in hypoxia-induced CA9 transcription. We hypothesized that obstructing the HIF-CA9 axis at two points via APE1/Ref-1 inhibition (which results in a decrease in CA9 expression) and direct CA9 inhibition results in enhanced PDAC cell killing under hypoxic conditions. In our studies, HIF1α-mediated induction of CA9 is significantly attenuated following APE1/Ref-1 knock down or redox signaling inhibition in patient-derived PDAC cells and pancreatic cancer-associated fibroblast cells using the APE1/Ref-1 redox signaling inhibitor APX3330 (currently in clinical trials). Additionally, dual-targeting of APE1/Ref-1 redox signaling activity and CA9 activity results in additive-to-synergistic enhancement of acidification and cytotoxicity of PDAC cells under hypoxic conditions as well as decreased tumor growth in an ex vivo 3-dimensional tumor co-culture model. These studies are clinically relevant as we used the CA9 inhibitor SLC-0111 (phase I clinical trial completed), as well as APX3330 (Apexian Pharmaceuticals: IND 125360), for which a phase I clinical trial has opened. Further experiments characterized novel analogs of APX3330: APX2009 and APX2014, which demonstrated up to 50-fold improved potency as measured by pH reduction, cytotoxicity, and inhibition of hypoxia-induced CA9 expression. An SLC-0111 analog, FC12-531A, demonstrated up to 75-fold improved potency as measured by cytotoxicity. In combination, these analogs resulted in synergistic inhibition of 3D tumor spheroid growth at nanomolar-to-low-micromolar concentrations. These results underscore the concept that proper combination therapy has significant clinical utility of blocking APE1/Ref-1 and CA9 function for novel PDAC therapeutic treatment.

Citation Format: Derek Logsdon, Fenil Shah, Fabrizio Carta, Claudiu Supuran, Melissa Fishel, Mark R. Kelley. APE1/Ref-1 redox signaling regulates HIF1a-mediated CA9 expression in hypoxic pancreatic cancer cells: Combination treatment in patient-derived pancreatic tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2941.

Discovery of Novel Nonsteroidal Anti-Inflammatory Drugs and Carbonic Anhydrase Inhibitors Hybrids (NSAIDs-CAIs) for the Management of Rheumatoid Arthritis

Herein we report the design as well as the synthesis of a new series of dual hybrid compounds consisting of the therapeutically used nonsteroidal-anti-inflammatory drugs (NSAIDs; i.e., indometacin, sulindac, ketoprofen, ibuprofen, diclofenac, ketorolac, etc., cyclooxygenase inhibitors) and the carbonic anhydrase inhibitor (CAIs) fragments of the sulfonamide type. Such compounds are proposed as new tools for the management of ache symptoms associated with rheumatoid arthritis (RA) and related inflammation diseases. The majority of the hybrids reported were effective in inhibiting the ubiquitous human (h) CA I and II as well as the RA overexpressed hCAs IX and XII isoforms, with K_I values comprised of the low-medium nanomolar ranges. The antihyperalgesic activity of selected compounds was assessed by means of the paw-pressure and incapacitance tests using an in vivo RA model, and among them the hybrids 6B and 8B showed potent antinociceptive effects lasting up to 60 min after administration.

Sialendoscopy for salivary stones: principles, technical skills and therapeutic experience

Obstructive sialadenitis is the most common non-neoplastic disease of the salivary glands, and sialendoscopy is increasingly used in both diagnosis and treatment, associated in selected cases with endoscopic laser lithotripsy. Sialendoscopy is also used for combined minimally invasive external and endoscopic approaches in patients with larger and proximal stones that would require excessively long laser procedures. The present paper reports on the technical experience from the Ear, Nose and Throat Unit of the Sant'Orsola-Malpighi Hospital of Bologna, and from the Department of Otorhinolaryngology of the University Hospital of Cagliari, Italy, including the retrospective analysis of the endoscopic and endoscopic assisted procedures performed on 48 patients (26 females and 22 males; median age 45.3; range 8-83 years) treated for chronic obstructive sialadenitis at the University Hospital of Cagliari from November 2010 to April 2016. The results from the Sant'Orsola-Malpighi Hospital of Bologna have been previously published. The technical aspects of sialendoscopy are carefully described. The retrospective analysis of the University Hospital of Cagliari shows that the disease was unilateral in 40 patients and bilateral in 8; a total of 56 major salivary glands were treated (22 submandibular glands and 34 parotids). Five patients underwent bilateral sialendoscopy for juvenile recurrent parotitis. 10 patients were treated for non-lithiasic obstructive disease. In 33 patients (68.75%) the obstruction was caused by salivary stones (bilateral parotid lithiasis in 1 case). Only 8 patients needed a sialectomy (5 submandibular glands and 3 parotids). The conservative approach to obstructive sialadenitis is feasible and can be performed either purely endoscopically or in a combined modality, with a high percentage of success. The procedure must be performed with dedicated instrumentation by a skilled surgeon after proper training since minor to major complications can be encountered. Sialectomy should be the "extrema ratio" after failure of a conservative approach.

Design, Synthesis, and X-ray of Selenides as New Class of Agents for Prevention of Diabetic Cerebrovascular Pathology

A series of novel selenides bearing benzenesulfonamide moieties was synthesized and investigated for their inhibition on six human (h) carbonic anhydrase (CA, EC 4.2.1.1) isoforms such as the physiologically relevant hCA I, II, VA, VB, VII, and IX and the X-ray complex in adduct with hCA II for some of them investigated. These enzymes are involved in a variety of diseases including glaucoma, retinitis pigmentosa, epilepsy, arthritis, metabolic disorders, and cancer. The investigated compounds showed potent inhibitory action against hCA VA, VII, and IX, in the low nanomolar range, thus making them of interest for the development of isoform-selective inhibitors and as candidates for various biomedical applications.

CO2 Permeability of Rat Hepatocytes and Relation of CO2 Permeability to CO2 Production

BACKGROUND/AIMS

It has been described that cells in culture with very low oxidative metabolism possess a low CO2 membrane permeability, PCO2, of ∼ 0.01 cm/s. On the other hand, cardiomyocytes and mitochondria with extremely high rates of O2 consumption exhibit very high CO2 membrane permeabilities of 0.1 and 0.3 cm/s, repectively. To ascertain that this represents a systematic relationship, we determine here PCO2 of hepatocytes, which exhibit an intermediate rate of O2 consumption.

METHODS

We isolated intact hepatocytes with vitalities of ∼ 70% from rat liver and measured their CO2 permeability by the previously published mass spectrometric 18O exchange technique.

RESULTS

We find a PCO2 of hepatocytes of 0.03 cm/s in the presence of FC5-208A and verapamil. FC5-208A was necessary to inhibt extracellular carbonic anhydrase, and verapamil was necessary to inhibit intracellular uptake of FC5-208A by the organic cation transporter OCT1 of hepatocytes.

CONCLUSION

Rat hepatocytes with their intermediate rate of oxygen consumption also possess an intermediate CO2 permeability. From pairs of data for five types of cells/organelles, we find an excellent positive linear correlation between PCO2 and metabolic rate, suggesting an adaptation of PCO2 to the rate of O2 consumption.

Inhibition of carbonic anhydrase IX targets primary tumors, metastases, and cancer stem cells: Three for the price of one

Human carbonic anhydrase (CA) IX is a tumor-associated protein, since it is scarcely present in normal tissues, but highly overexpressed in a large number of solid tumors, where it actively contributes to survival and metastatic spread of tumor cells. Due to these features, the characterization of its biochemical, structural, and functional features for drug design purposes has been extensively carried out, with consequent development of several highly selective small molecule inhibitors and monoclonal antibodies to be used for different purposes. Aim of this review is to provide a comprehensive state-of-the-art of studies performed on this enzyme, regarding structural, functional, and biomedical aspects, as well as the development of molecules with diagnostic and therapeutic applications for cancer treatment. A brief description of additional pharmacologic applications for CA IX inhibition in other diseases, such as arthritis and ischemia, is also provided.

Synthesis of N'-phenyl-N-hydroxyureas and investigation of their inhibitory activities on human carbonic anhydrases

A series of N'-phenyl-N-hydroxyureas has been prepared by reacting hydroxylamine with aromatic isocyanates. These compounds were investigated as inhibitors of human carbonic anhydrases (hCAs, EC 4.2.1.1), considering four physiologically relevant isoforms, the cytosolic isoforms hCA I and II, and tumor associated, transmembrane isoforms hCA IX and XII. The new compounds reported here did not inhibit the widespread cytosolic isoforms hCA I and II, but they inhibited the tumor associated isoforms with interesting potencies. The most effective inhibitors showed K_Is ranging between 72.8 and 78.9 nM against hCA IX and between 6.9 and 7.2 against hCA XII, making them of interest as candidates for antitumor studies.

Corneal Graft Rejection after Penetrating Keratoplasty for Keratoconus in Turner's Syndrome

Purpose

To report a patient with Turner's syndrome who developed graft rejection after penetrating keratoplasty (PK) for keratoconus and to review the ophthalmic literature on the association between keratoconus and Turner's syndrome.

Methods

A woman with bilateral keratoconus and Turner's syndrome (45,XO) was referred for progressive visual loss in the right eye. Best-corrected visual acuity was 20/400 in the right eye. Slit-lamp examination revealed corneal thinning with ectatic protrusion of the central cornea and Vogt's striae in the right eye. The patient underwent PK in the right eye in January 2001. She developed graft rejection in April 2003 and visual acuity dropped to hand motion. After treatment with topical and systemic steroids and systemic cyclosporine A, visual acuity recovered to 20/80 in July 2003.

Results

The authors know of only three other reported patients (six eyes) with keratoconus in Turner's syndrome. Five eyes underwent PK with good visual rehabilitation, but one developed immunologic graft rejection 7 years after surgery. On the whole, considering the current report and the other cases described in the literature, graft rejection occurred in 2 out of 6 eyes (33.3%). The graft survival rate was 80% after 2 years and 40% after 7 years.

Conclusions

The results suggest that grafts for keratoconus in patients with Turner's syndrome might have an increased risk of immunologic rejection. Corneal grafts in Turner's syndrome need to be monitored closely. Early detection of graft rejection and aggressive treatment with topical and systemic steroids and systemic cyclosporine A can save the graft and restore useful vision.

Natural extracellular nanovesicles and photodynamic molecules: is there a future for drug delivery?

Photodynamic molecules represent an alternative approach for cancer therapy for their property (i) to be photo-reactive; (ii) to be not-toxic for target cells in absence of light; (iii) to accumulate specifically into tumour tissues; (iv) to be activable by a light beam only at the tumour site and (v) to exert cytotoxic activity against tumour cells. However, to date their clinical use is limited by the side effects elicited by systemic administration. Extracellular vesicles are endogenous nanosized-carriers that have been recently introduced as a natural delivery system for therapeutic molecules. We have recently shown the ability of human exosomes to deliver photodynamic molecules. Therefore, this review focussed on extracellular vesicles as a novel strategy for the delivery of photodynamic molecules at cancer sites. This completely new approach may enhance the delivery and decrease the toxicity of photodynamic molecules, therefore, represent the future for photodynamic therapy for cancer treatment.

Inhibition of the β-carbonic anhydrase from the dandruff-producing fungus Malassezia globosa with monothiocarbamates

A series of monothiocarbamates (MTCs) was investigated for the inhibition of the β-class carbonic anhydrase (CAs, EC 4.2.1.1) from the fungal parasite Malassezia globosa, MgCA. These MTCs incorporate various scaffolds, among which aliphatic amine with 1–4 carbons atom in their molecule, morpholine, piperazine, as well as phenethylamine and benzylamine derivatives. All the reported MTCs displayed a better efficacy in inhibiting MgCA compared to the clinically used sulphonamide drug acetazolamide (K_I of 74 μM), with K_Is spanning between 1.85 and 18.9 μM. The homology model of the enzyme previously reported by us was used to rationalize the results by docking some of these MTCs within the fungal CA active site. This study might be useful to enrich the knowledge of the MgCA inhibition profile, eliciting novel ideas pertaining the design of modulators with potential efficacy in combatting dandruff or other fungal infections.

Synthesis and carbonic anhydrase I, II, VII, and IX inhibition studies with a series of benzo[d]thiazole-5- and 6-sulfonamides

A series of benzo[d]thiazole-5- and 6-sulfonamides has been synthesized and investigated for the inhibition of several human (h) carbonic anhydrase (CA, EC 4.2.1.1) isoforms, using ethoxzolamide (EZA) as lead molecule. 2-Amino-substituted, 2-acylamino- and halogenated (bromo-and iodo-derivatives at the heterocyclic ring) compounds led to several interesting inhibitors against the cytosolic hCA I, II and VII, as well as the transmembrane, tumor-associated hCA IX isoforms. Several subnanomolar/low nanomolar, isoform-selective sulfonamide inhibitors targeting hCA II, VII and IX were detected. The sharp structure-activity relationship for CA inhibition with this small series of derivatives, with important changes of activity observed even after minor changes in the scaffold or at the 2-amino moiety, make this class of scarcely investigated sulfonamides of particular interest for further investigations.

Discovery of New Selenoureido Analogues of 4-(4-Fluorophenylureido)benzenesulfonamide as Carbonic Anhydrase Inhibitors

A series of benzenesulfonamides bearing selenourea moieties was obtained considering the ureido-sulfonamide SLC-0111, in Phase I clinical trials as antitumor agent, as a lead molecule. All compounds showed interesting inhibition potencies against the physiologically relevant human (h) carbonic anhydrase (hCAs, EC 4.2.1.1) isoforms I, II, IV, and IX. The most flexible analogues in the series 14-19 showed low nanomolar inhibition constants against hCA I, II, and IX. We assessed selected compounds on the in vitro antioxidant properties and binding modes and evaluated ex vivo human prostate (PC3), breast (MDA-MB-231), and colon-rectal (HT-29) cancer cell lines both in normoxic and hypoxic conditions.

β-CA-specific inhibitor dithiocarbamate Fc14-584B: a novel antimycobacterial agent with potential to treat drug-resistant tuberculosis

Inhibition of novel biological pathways in Mycobacterium tuberculosis (Mtb) creates the potential for alternative approaches for treating drug-resistant tuberculosis. In vitro studies have shown that dithiocarbamate-derived β-carbonic anhydrase (β-CA) inhibitors Fc14–594 A and Fc14–584B effectively inhibit the activity of Mtb β-CA enzymes. We screened the dithiocarbamates for toxicity, and studied the in vivo inhibitory effect of the least toxic inhibitor on M. marinum in a zebrafish model. In our toxicity screening, Fc14–584B emerged as the least toxic and showed minimal toxicity in 5-day-old larvae at 300 µM concentration. In vitro inhibition of M. marinum showed that both compounds inhibited growth at a concentration of 75 µM. In vivo inhibition studies using 300 µM Fc14–584B showed significant (p > .05) impairment of bacterial growth in zebrafish larvae at 6 days post infection. Our studies highlight the therapeutic potential of Fc14–584B as a β-CA inhibitor against Mtb, and that dithiocarbamate compounds may be developed into potent anti-tuberculosis drugs.

Advances in new psychoactive substances identification: the U.R.I.To.N. Consortium

Identification of new psychoactive substances (NPS) in biological and non-biological samples represents a hard challenge for forensic toxicologists. Their great chemical variety and the speed with which new NPS are synthesised and spread make stringent the need of advanced tools for their detection based on multidisciplinary approaches. For this reason, in August 2016, the "Unit of Research and Innovation in Forensic Toxicology and Neuroscience of Addiction" (U.R.I.To.N.) was founded by the Forensic Toxicology Division of the University of Florence. In this Research Unit, various professionals (i.e. forensic toxicologists, chemists, physicians) collaborate to study all the aspects of drugs of abuse, especially NPS. Herein, we describe the multidisciplinary approach comprising liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), gas chromatography hyphenated to mass spectrometry (GC-MS) and solution nuclear magnetic resonance analysis that allowed the identification of three NPS such as 1-(benzofuran-5-yl)-N-methylpropan-2-amine, 2-amino-1-(4-bromo-2,5-dimethoxyphenyl)ethan-1-one (bk-2C-B), and 3-(2-aminopropyl)indole (α-methyltryptamine) in seized materials.

Abstract 2931: Targeting membrane-bound carbonic anhydrases in breast cancer to intervene in the metastatic phenotype

Breast cancer is the second leading cause of cancer related deaths among women in the United States. Despite the tremendous progress that has been made towards treating localized tumors, nearly 40,000 women die each year, predominantly from metastatic drug resistance. The tumor microenvironment plays a pivotal role in determining tumor growth, invasion, metastasis, and therapeutic success or failure. Therefore, a therapy targeting the tumor microenvironment is needed to sufficiently preserve the quality of life of cancer patients, by inhibiting metastasis. Elevated levels of Carbonic anhydrase IX (CAIX) expression in primary breast cancers is a marker for highly aggressive and metastatic tumors, especially of the triple negative subtype (TNBC). It is also associated with hypoxia, extracellular acidification, and poor prognosis. Low pH (values of ~6.5-6.8) is toxic to normal cells in the tumor microenvironment while enhancing cancer cell proliferation and tumor growth. Our goal was to compare the structure of a CAIX-mimic bound to ureidosulfonamide inhibitors with the biological activity of these inhibitors in triple negative and estrogen receptor positive (ER+) breast cancer cell lines. CAIX is a reversible enzyme and at low pH (high proton concentration), the enzyme will consume protons, raising pH. Our hypothesis is that CAIX inhibition, in the context of an acidic microenvironment, will dysregulate its ability to maintain the acidic pH preferred by cancer cells which favors their growth and migration. In this study, we have shown the interaction of sulfonamide-based inhibitors with a CAIX-mimic using X-ray crystallography. These structures show that the inhibitors make multiple contacts within the active site cavity. This is consistent with the inhibitor-induced decrease in CAIX activity and to some extent expression. We have also investigated the effect of CA inhibition on breast cancer cell growth, proliferation, activation of cell death pathways and migration. This reveals that, although CA inhibition with the sulfonamide-based compounds inhibits cell growth and migration, it does not activate apoptotic pathways. In total, these observations indicate that CAIX is a viable small molecular drug target for the treatment of metastatic breast cancer.

Citation Format: Mam Y. Mboge, Zhijuan Chen, Brian P. Mahon, Chingkkuang Tu, Alyssa S. Wolff, John V. Mathias, Fabrizio Carta, Claudiu T. Supuran, Rob McKenna, Susan C. Frost. Targeting membrane-bound carbonic anhydrases in breast cancer to intervene in the metastatic phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2931. doi:10.1158/1538-7445.AM2017-2931

Structure activity study of carbonic anhydrase IX: Selective inhibition with ureido-substituted benzenesulfonamides

Ureido-substituted benzenesulfonamides (USBs) show great promise as selective and potent inhibitors for human carbonic anhydrase hCA IX and XII, with one such compound (SLC-0111/U-F) currently in clinical trials (clinical trials.gov, NCT02215850). In this study, the crystal structures of both hCA II (off-target) and an hCA IX-mimic (target) in complex with selected USBs (U-CH3, U-F, and U-NO2), at resolutions of 1.9 Å or better, are presented, and demonstrate differences in the binding modes within the two isoforms. The presence of residue Phe 131 in hCA II causes steric hindrance (U-CH3, 1765 nM; U-F, 960 nM; U-NO2, 15 nM) whereas in hCA IX (U-CH3, 7 nM; U-F, 45 nM; U-NO2, 1 nM) and hCA XII (U-CH3, 6 nM; U-F, 4 nM; U-NO2, 6 nM), 131 is a Val and Ala, respectively, allows for more favorable binding. Our results provide insight into the mechanism of USB selective inhibition and useful information for structural design and drug development, including synthesis of hybrid USB compounds with improved physiochemical properties.

N-Substituted and ring opened saccharin derivatives selectively inhibit transmembrane, tumor-associated carbonic anhydrases IX and XII

A series of N-substituted saccharins incorporating aryl, alkyl and alkynyl moieties, as well as some ring opened derivatives were prepared and investigated as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). The widespread cytosolic isoforms CA I and II were not inhibited by these sulfonamides whereas transmembrane, tumor-associated ones were effectively inhibited, with K_Is in the range of 22.1-481nM for CA IX and of 3.9-245nM for hCA XII. Although the inhibition mechanism of these tertiary/secondary sulfonamides is unknown for the moment, the good efficacy and especially selectivity for the inhibition of the tumor-associated over the cytosolic, widespread isoforms, make these derivatives of considerable interest as enzyme inhibitors with various pharmacologic applications.