Aromatase inhibitors for chemoprevention

A new triazolothiadiazine derivative inhibits stemness and induces cell death in HCC by oxidative stress dependent JNK pathway activation

Hepatocellular carcinoma (HCC) is a highly heterogeneous cancer, and resistant to both conventional and targeted chemotherapy. Recently, nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to decrease the incidence and mortality of different types of cancers. Here, we investigated the cellular bioactivities of a series of triazolothiadiazine derivatives on HCC, which have been previously reported as potent analgesic/anti-inflammatory compounds. From the initially tested 32 triazolothiadiazine NSAID derivatives, 3 compounds were selected based on their IC₅₀ values for further molecular assays on 9 different HCC cell lines. 7b, which was the most potent compound, induced G2/M phase cell cycle arrest and apoptosis in HCC cells. Cell death was due to oxidative stress-induced JNK protein activation, which involved the dynamic involvement of ASK1, MKK7, and c-Jun proteins. Moreover, 7b treated nude mice had a significantly decreased tumor volume and prolonged disease-free survival. 7b also inhibited the migration of HCC cells and enrichment of liver cancer stem cells (LCSCs) alone or in combination with sorafenib. With its ability to act on proliferation, stemness and the migration of HCC cells, 7b can be considered for the therapeutics of HCC, which has an increased incidence rate of ~ 3% annually.

Synthesis, Characterization, Antimicrobial and Antioxidant Activities of 1,2,4-triazolyl-isoxazole Moieties via Dehydration Reactions of Carbohydrazides

Abstract:

For the reason of distinct place in the field of medicinal and pharmaceutical chemistry of 1,2,4-triazole derivatives, a new class of fused 1,2,4-triazolyl-isoxazole moieties was prepared from 3- (2,4,6-trimethoxyphenyl)isoxazolo-4,5-bis[carbonyl-(4̍-phenyl) thiosemicarbazide via dehydration reactions of carbohydrazides by using the appropriate chemical reagents. The structures of the compounds were elucidated by both elemental and spectral (IR, NMR and MS) analyses. The in vitro antioxidant activity of the new compounds was determined by free radical scavenging and metal chelating activity. All the synthesized compounds showed good activity according to free radical scavenging and metal chelating activity compared with standards. The new compounds were screened in vitro antibacterial activity against three gram-positive bacteria and three gram-negative bacteria.

Synthesis and evaluation of antibacterial and antioxidant activity of novel 2-phenyl-quinoline analogs derivatized at position 4 with aromatically substituted 4H-1,2,4-triazoles

A set of novel quinolone-triazole conjugates (12-31) were synthesized in three steps in good yields starting from 2-phenylquinoline-4-carboxylic acid. All the intermediates, as well as the final 1,2,4-triazolyl quinolines were fully characterized by their detailed spectral analysis utilizing different techniques such as IR, ¹H NMR, ¹³C NMR, and finally mass spectrometry. All the synthesized compounds were evaluated in vitro for their potential antibacterial activity and their preliminary safety profile was assessed through cytotoxicity assay. Additionally, six selected conjugates were evaluated for their antioxidative properties on the basis of density functional theory calculations, using radical scavenging assay (DPPH) and cellular antioxidant assay. The reported results encourage further investigation of selected compounds and are shading light on their potential pharmacological use.

New Norcantharidin Analogs: Synthesis and Anticancer Activity

The reaction of direct condensation between S-ethyl-N-(7-oxabicyclo-[2.2.1]heptane-2,3-dicarbonyl)isothiosemicarbazide (1) and primary amines was used for synthesizing new N-substituted amides of 3-(3-ethylthio-1,2,4-triazol-5-yl)-7-oxabicyclo-[2.2.1]heptane-2-carboxylic acid (2-12) as norcantharadin analogs. Moreover, the anticancer activity of the obtained compounds was studied. Among all compounds, the N-3-methylbutyl amide of 3-(3-ethylthio-1,2,4-triazol-5-yl)-7-oxabicyclo-[2.2.1]heptane-2-carboxylic acid (4) presented selective in vitro toxic and antiproliferative effects against the human hepatoma cell line Hep3B, without affecting normal human liver stellate cells (LX-2 cell line).

Associations between genetic variants and the effect of letrozole and exemestane on bone mass and bone turnover

Adjuvant therapy for hormone receptor (HR) positive postmenopausal breast cancer patients includes aromatase inhibitors (AI). While both the non-steroidal AI letrozole and the steroidal AI exemestane decrease serum estrogen concentrations, there is evidence that exemestane may be less detrimental to bone. We hypothesized that single nucleotide polymorphisms (SNP) predict effects of AIs on bone turnover. Early stage HR-positive breast cancer patients were enrolled in a randomized trial of exemestane versus letrozole. Effects of AI on bone mineral density (BMD) and bone turnover markers (BTM), and associations between SNPs in 24 candidate genes and changes in BMD or BTM were determined. Of the 503 enrolled patients, paired BMD data were available for 123 and 101 patients treated with letrozole and exemestane, respectively, and paired BTM data were available for 175 and 173 patients, respectively. The mean change in lumbar spine BMD was significantly greater for letrozole-treated (-3.2 %) compared to exemestane-treated patients (-1.0 %) (p = 0.0016). Urine N-telopeptide was significantly increased in patients treated with exemestane (p = 0.001) but not letrozole. Two SNPs (rs4870061 and rs9322335) in ESR1 and one SNP (rs10140457) in ESR2 were associated with decreased BMD in letrozole-treated patients. In the exemestane-treated patients, SNPs in ESR1 (Rs2813543) and CYP19A1 (Rs6493497) were associated with decreased bone density. Exemestane had a less negative impact on bone density compared to letrozole, and the effects of AI therapy on bone may be impacted by genetic variants in the ER pathway.

Extended adjuvant therapy with letrozole: reducing the risk of recurrence

Patients with all stages of primary breast cancer are at continuing risk of relapse following 5 years of adjuvant tamoxifen therapy, even in the absence of lymph node involvement. Tamoxifen has been the standard therapy for reducing risk of recurrence, although more than 50% of relapses and deaths occur after completion of tamoxifen. Tamoxifen use is associated with an increased risk of serious side effects, and extended use beyond 5 years may have a negative impact on disease-free survival. Extended adjuvant letrozole therapy confers a significant benefit in relapse-free survival. The approval of letrozole for this indication in the USA and in many European countries introduces a new, safe and effective treatment for disease-free patients seeking to reduce their long-term risk of recurrence.

Evaluation of a Schiff base copper complex compound as potent anticancer molecule with multiple targets of action

Copper is a biologically relevant metal as it is associated with various biomolecules related to essential physiological activities. Anticancer compounds with copper as a metal center is hypothesized to be less toxic and more potent. In the present study we have tested the efficacy of a family of Schiff base copper complexes of which the best compound was [Cu(Pyimpy)Cl(2)] where Pyimpy is a tridentate ligand containing two pyridine and one imine nitrogen donor. [Cu(Pyimpy)Cl(2)], represented as CuP1, was checked for its anticancer potential. The IC(50) value of CuP1 was found to be 4.29±0.42, 6.34±0.58 and 5.32±0.38 μM in MCF-7, PC3 and HEK 293 cells respectively. It was found to cause in vitro DNA fragmentation in comet assays and acridine orange staining of MCF 7 cells. CuP1 was further tested on rat breast tumor models and was found to inhibit tumor growth. It caused apoptosis within the tumor by the up regulation of caspase pathway and inhibition of the Akt, matrix metalloproteinase 9 and α-methyl acyl CoA racemase. Antioxidant enzymes which in general results in drug resistant condition in tumor tissues were significantly inhibited by this copper compound (P<0.05). Further, CuP1 did not show any prominent systemic toxicity. These results indicate that CuP1 can be a potential anticancer agent and further investigation will reveal more about its mode of action.

2-Benzoylmethyl-4-[(2-benzylidene-ethylidene)amino]-5-(2-thienylmethyl)-2H-1,2,4-triazol-3(4H)-one

In the mol­ecule of the title compound, C₂₄H₂₀N₄O₂S, the dihedral angle between the triazole and thio­phene rings is 66.80 (4)° and the dihedral angle between the two benzene rings is 63.37 (4)°. An intra­molecular C—H⋯O inter­action results in the formation of a six-membered ring. A π⋯π contact between the benzene rings, [centroid–centroid distance = 3.918 (2) Å] may stabilize the structure. Weak C—H⋯π inter­actions are also present. The S, C and H atoms of the thiophene ring are disordered over two positions and were refined with occupancies of 0.654 (3) and 0.346 (3).

The NSABP Study of Tamoxifen and Raloxifene (STAR) trial

In the Study of Tamoxifen and Raloxifene (STAR) trial, postmenopausal women at increased risk of breast cancer received either oral tamoxifen (20 mg/day) or raloxifene (60 mg/day) over 5 years. There were an equal number of cases of invasive breast cancer in women assigned to tamoxifen and raloxifene. There were fewer cases of noninvasive breast cancer in the tamoxifen group than in the raloxifene group (risk ratio [RR]: 1.40; 95% confidence interval [CI]: 0.98-2.02). There were more cases of uterine cancer with tamoxifen than with raloxifene (RR: 0.62; 95% CI: 0.35-1.08). Thromboembolic events occurred less often in the raloxifene group (RR: 0.70; 95% CI: 0.54-0.91) and there were fewer cataracts and cataract surgeries in the women taking raloxifene (RR: 0.79; 95% CI: 0.68-0.92). The STAR trial has shown that raloxifene is as effective as tamoxifen in reducing the risk of invasive breast cancer and has a lower risk of adverse events but a nonstatistically significant higher risk of noninvasive breast cancer. The risk of other cancers, fractures, ischemic heart disease and stroke is similar for both drugs.

Aromatase inhibitors for breast cancer: proven efficacy across the spectrum of disease

For more than 100 years, hormonal therapy has been known to be effective in the treatment of breast cancer. Initially, this therapy was dominated by the selective estrogen receptor antagonists such as tamoxifen. Aromatase inhibitors (AIs) are a distinct drug class with demonstrated activity in the treatment of hormone-sensitive breast cancer. All 3 third-generation AIs, exemestane, anastrozole, and letrozole, have been studied in multiple lines of therapy in advanced breast cancer and have demonstrated equivalence or superiority compared with tamoxifen. While initially developed as a treatment option for advanced disease, the AIs have also shown efficacy in the treatment of curable disease, including the neoadjuvant and adjuvant settings. In addition, the AIs demonstrate a tolerable side effect profile in comparison with tamoxifen, and this has led to their early incorporation as standard of care therapy. Given the proven efficacy of AIs across the spectrum of breast cancer, the remaining questions include definitive sequencing strategy, timing, and duration of use. Ongoing trials include head-to-head comparisons between the AIs in early-stage breast cancer; the results of these trials are eagerly anticipated and should further optimize the use of AIs.

Synthesis of 1,2,4-triazole C-nucleosides from hydrazonyl chlorides and nitriles

A series of 1,3-diaryl-5-(2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl)-1H-1,2,4-triazole nucleosides (3a-f) were synthesized via the intermolecular cyclization of hydrazonyl chlorides with peracylated ribofuranosyl cyanide catalyzed by Yb(OTf)3 or AgNO3, respectively. Similarly, the 1,2,4-triazole of glucopyranosyl C-nucleosides 5a,b were prepared from the hydrazonyl chlorides and the nitrile 4. Alternatively, the 1,2,4-triazole N-nucleoside 8 was obtained from cyclization of the unsymmetrical bis[alpha-(4-methoxyphenyl)aminobenzylidene]-hydrazine with peracylated 1-amino-D-manno-pentitol.

Progress in chemoprevention drug development: the promise of molecular biomarkers for prevention of intraepithelial neoplasia and cancer--a plan to move forward

This article reviews progress in chemopreventive drug development, especially data and concepts that are new since the 2002 AACR report on treatment and prevention of intraepithelial neoplasia. Molecular biomarker expressions involved in mechanisms of carcinogenesis and genetic progression models of intraepithelial neoplasia are discussed and analyzed for how they can inform mechanism-based, molecularly targeted drug development as well as risk stratification, cohort selection, and end-point selection for clinical trials. We outline the concept of augmenting the risk, mechanistic, and disease data from histopathologic intraepithelial neoplasia assessments with molecular biomarker data. Updates of work in 10 clinical target organ sites include new data on molecular progression, significant completed trials, new agents of interest, and promising directions for future clinical studies. This overview concludes with strategies for accelerating chemopreventive drug development, such as integrating the best science into chemopreventive strategies and regulatory policy, providing incentives for industry to accelerate preventive drugs, fostering multisector cooperation in sharing clinical samples and data, and creating public-private partnerships to foster new regulatory policies and public education.

New aromatase inhibitors as second-line endocrine therapy in postmenopausal patients with metastatic breast carcinoma: a pooled analysis of the randomized trials

BACKGROUND

New aromatase inhibitors (AI) (second-generation: formestane and fadrozole; third-generation: letrozole, anastrozole, vorozole, and exemestane) have been tested in several controlled clinical trials after tamoxifen failure in metastatic breast carcinoma (MBC). They have resulted in better survival compared with megestrol acetate (MEG) in a number of studies. The authors performed a pooled analysis including all the Phase III trials published between 1996 and 2004 evaluating the AIs approved or not by the Food and Drug Administration (FDA) and the European Agency for the Evaluation of Medical Products (EMEA) as second-line endocrine therapy (ET) for patients with MBC.

METHODS

The overall response rate (ORR) and time to disease progression (TTP) were considered the primary end points, whereas toxicity was regarded as a secondary objective. Relative risk, 95% confidence interval, and heterogeneity were derived using 2 methods.

RESULTS

No significant differences in ORR and TTP were noted in the entire group of 9 trials comparing AI with MEG (3908 patients) and in the 6 trials comparing nonsteroidal AI and MEG (2415 patients). AI yielded significantly more hot flashes than MEG (P = 0.004) but caused significantly less toxicity than MEG in weight gain (P = 0.001), dyspnea (P = 0.008), and peripheral edema (P = 0.03). Significant heterogeneity for nausea, weight gain, dyspnea, and peripheral edema was registered. When steroidal AIs were excluded from the toxicity analysis, nausea maintained its strongly significant heterogeneity (P = 0.0002), whereas weight gain, dyspnea, and peripheral edema lost their significance.

CONCLUSIONS

This pooled analysis suggested that AIs in second-line ET for patients with MBC do not seem to add any significant benefit to MEG in terms of ORR and TTP. With regard to toxicity, the findings in the current study showed that weight gain, dyspnea, and peripheral edema are more frequent with the use of MEG, whereas hot flashes were more represented using AI.

Prophylaxis approach to a-symptomatic post-menopausal women: Breast cancer

Breast cancer is the most common cancer of women worldwide. Its frequency increases throughout the female lifespan. Epidemiological research has clearly identified important reproductive risk factors for breast cancer, including age at menarche, age at menopause, age at first-term pregnancy and nulliparity, which provide important clues to the hormonal origin of this disease. The widespread use of exogenous sex steroids as contraceptive agents and as hormonal replacement therapy has been a source of concern and generates discussion about their effects on breast health. Lifestyle changes, exercise or diet could play a role in primary prevention of breast cancer. Regular exercise, ingestion of adequate amounts of fruit and vegetables, limiting alcohol consumption, avoidance of obesity in post-menopausal women, and perhaps the use of olive oil, may all have a protective effect and should be considered by women. There is insufficient scientific evidence of the role played by phyto-oestrogens on breast cancer risk. Other preventive measures that include the use of drugs such as statins or aspirin should not be recommended until we have more information about their effects on the breast. Especially for high-risk women, all the aforementioned measures may be not enough, and chemo-prevention should be considered. The use of selective oestrogen receptor modulators (SERMs) to reduce breast cancer risk is still being evaluated. Tamoxifen was the first SERM approved for the reduction of breast cancer incidence in women at high risk. However its use has limitations, due to significant side effects. Raloxifene has been approved for the prevention and treatment of post-menopausal osteoporosis and has provided excellent indications of breast cancer risk reduction, with a more favourable profile than tamoxifen.

Synthesis and antimicrobial activities of some new 1-(5-phenylamino-[1,3,4]thiadiazol-2-yl)methyl-5-oxo-[1,2,4]triazole and 1-(4-phenyl-5-thioxo-[1,2,4]triazol-3-yl)methyl-5-oxo- [1,2,4]triazole derivatives

Acetic acid ethyl esters containing 5-oxo-[1,2,4]triazole ring (2) were synthesized by the condensation of compounds 1a-f with ethyl bromoacetate in basic media. The reaction of compounds 2a-f with hydrazine hydrate led to the formation of acid hydrazides (3a-f). The treatment of compounds 3 with two divers aromatic aldehydes resulted in the formation of arylidene hydrazides as cis-trans conformers (4a,c,e,f, 5a,e,f). The thiosemicarbazide derivatives (6a,c,d,f) were afforded by the reaction of corresponding compounds 3 with phenylisothiocyanate. The treatment of compounds 6a,c,d,f with sulfuric acidic caused the conversion of side-chain of compounds 6a,c,d,f into 1,3,4-thiadiazol ring; thus, compounds 7a,c,d,f were obtained. On the other hand, the cyclization of compounds 6a,c,d,f in the presence of 2 N NaOH resulted in the formation of compounds 8a,c,d,f containing two [1,2,4]triazole rings which are linked to each other via a methylene bridge. Compounds 4a, f, 5a, 7a, d, f, 8a and d have shown antimicrobial activity against one or more microorganism, but no antifungal activity has been observed against yeast like fungi. Also inhibitory effect on mycelial growth by compounds 4e, 7d and 8f has been observed. Compounds 4c and 5f were found to possess antitumor active towards breast cancer.

Towards an integrated model for breast cancer etiology: the lifelong interplay of genes, lifestyle, and hormones

While the association of a number of risk factors, such as family history and reproductive patterns, with breast cancer has been well established for many years, work in the past 10–15 years also has added substantially to our understanding of disease etiology. Contributions of particular note include the delineation of the role of endogenous and exogenous estrogens to breast cancer risk, and the discovery and quantification of risk associated with several gene mutations (e.g. BRCA1). Although it is difficult to integrate all epidemiologic data into a single biologic model, it is clear that several important components or pathways exist. Early life events probably determine both the number of susceptible breast cells at risk and whether mutations occur in these cells. High endogenous estrogens are well established as an important cause of breast cancer, and many known risk factors appear to operate through this pathway. Estrogens (and probably other growth factors) appear to accelerate the development of breast cancer at many points along the progression from early mutation to tumor metastasis, and appear to be influential at many points in a woman's life. These data now provide a basis for a number of strategies that can reduce risk of breast cancer, although some strategies represent complex decision-making. Together, the modification of nutritional and lifestyle risk factors and the judicious use of chemopreventive agents could have a major impact on breast cancer incidence. Further research is needed in many areas, but a few specific arenas are given particular mention.

Role of aromatase inhibitors in the treatment of breast cancer

BACKGROUND

Estrogens play a pivotal role in the development of breast cancer. Endocrine therapy based on estrogen blockade is a well-established treatment in hormone-dependent breast cancer. Tamoxifen citrate has long been considered the "gold standard" due to its relative safety and efficacy. Aromatase inhibitors are anti-estrogen agents that target specifically the aromatase enzyme, which is the final step in the estrogen production. The first use of aromatase inhibitors in breast cancer was associated with adverse effects such as rash, drowsiness, and adrenal-gland suppression. Newer third-generation agents are emerging as potential alternatives to tamoxifen, associating clinical efficacy with a more favorable safety profile.

OBJECTIVES

The aim of this article is to review the mechanisms of actions pharmacology, adverse effects, and clinical applications of the aromatase inhibitors available in the United States.

METHODS

The terms breast cancer or neoplasia, aromatase, aromatase inhibitors, third-generation, endocrine therapy, and antiestrogens were used to search MEDLINE for English-language studies published between 1966 and April 2004. A parallel search was performed at the corresponding Web site of each of the aromatase inhibitors available in the United States. Identified publications relevant to the article objectives were selected.

RESULTS

Anastrozole, letrozole, and exemestane are the 3 commercially available aromatase inhibitors approved by the US Food and Drug Administration for the treatment of hormone receptor-positive breast cancer in postmenopausal women. They have been used in several clinical scenarios, including advanced and early disease and chemoprevention, and in the neoadjuvant setting. There is evidence that aromatase inhibitors are more effective and tolerable than tamoxifen in advanced breast cancer and in the neoadjuvant setting. Based on the results of a large, randomized trial, their use in early disease and in chemoprevention is also promising. Aromatase inhibitors appear safe; however, the long-term safety profile is still unknown, especially concerning bone metabolism.

CONCLUSION

Third-generation aromatase inhibitors are a new treatment modality in estrogen and/or progesterone-receptor positive breast cancer. Although they are replacing the "classic" antiestrogen agents used in metastatic breast cancer, their benefit in early disease and as chemopreventive agents is not completely clear. Ongoing clinical studies should become available within the next few years and will provide additional recommendations for their use in patients with breast cancer.