A new selective estrogen receptor modulator, CHF 4227.01, preserves bone mass and microarchitecture in ovariectomized rats.

UNLABELLED: A new SERM, CHF 4227.01, given to 6-month-old female rats immediately after ovariectomy, preserved bone mass and bone microarchitecture without affecting uterus weight. It also decreased serum cholesterol and fat mass in estrogen-deficient rats. INTRODUCTION: We tested the effect of a new benzopyran derivative, CHF 4227.01, with selective estrogen receptor modulator (SERM) activity on bone mass and biomechanics in ovariectomized (OVX) female rats in comparison with 17alpha-ethinylestradiol (EST), raloxifene (RLX), and lasofoxifene (LFX). MATERIALS AND METHODS: Four doses of CHF 4227.01 (0.001, 0.01, 0.1, and 1 mg/kg body weight [bw]/day) were administered in OVX animals daily by gavage 5 days/week for 4 months. EST was administered at a dose of 0.1 mg/kg bw/day, whereas RLX and LSX were administered at doses of 1 and 0.1 mg/kg bw/day, respectively, by gavage. In one group (Sham), rats were operated but the ovaries not removed; another OVX group was treated only with placebo. RESULTS AND CONCLUSIONS: Treatment with CHF 4227.01 (1.0 and 0.1 mg/kg bw), EST (0.1 mg/kg bw), LFX (0.1 mg/kg bw), or RLX (1.0 mg/kg bw) prevented bone loss on the lumbar spine and the proximal femur assessed in vivo by DXA. Volumetric BMD obtained by pQCT ex vivo confirmed protection from bone loss in the spine and proximal femur among rats treated with CHF 4227.01. This effect was associated with strong inhibition of bone resorption both histologically and biochemically. Furthermore, CHF 4227.01 preserved trabecular microarchitecture, analyzed by muCT, and maintained biomechanical indices of bone strength in the spine and proximal femur, effects also observed for RLX, whereas LSX was less protective of microarchitecture. CHF 4227.01 treatment did not affect uterine weight, prevented the increase in body weight and fat mass seen in OVX animals, and decreased serum cholesterol to below the average of intact animals. In conclusion, CHF 4227.01 exhibits a promising therapeutic and safety profile as a new SERM on both skeletal and extraskeletal outcomes.

Synthesis, pharmacological evaluation, and structure-activity relationships of benzopyran derivatives with potent SERM activity.

The synthesis, binding affinity for estrogen receptor subtypes (ER alpha and ER beta) and pharmacological activity on rat uterus of a new class of potent ligands, characterized by a 3-phenylbenzopyran scaffold with a basic side chain in position 4, are reported. Some of these compounds, endowed with very high receptor affinity, showed potent inhibition of agonist-stimulated uterine growth, with no or limited proliferative effect. Binding affinity mostly depended on the nature and position of substituents at the 3-phenyl ring, while the uterine activity seems to be affected by basic chain length. Compound 9c (CHF4227) showed excellent binding affinity and antagonist activity on the uterus. The docking of benzopyran derivatives explained the structure-affinity relationships observed for 3-phenyl substitution: a small, hydrophobic 4'-substituent could interact with a small accessory binding cavity, while di-substitution at 4' and 3' led to some ER alpha selectivity. This selectivity can be ascribed to differences in amino acid composition and side chain conformation in the region accommodating the 3-phenyl ring at human ER alpha and ER beta ligand-binding domain.

Pharmacological actions of a novel, potent, tissue-selective benzopyran estrogen.

We have identified a new benzopyran derivative, 3-(4-methoxy) phenyl-4-[[4-[2-(1-piperidinyl)ethoxy]phenyl]methyl]-2H-1-benzopyran-7-ol hydrochloride (CHF 4227), with improved in vivo estrogen agonist/antagonist effects. CHF 4227 binds with high affinity to the human estrogen receptor-alpha and -beta (dissociation constant K(i) = 0.017 and 0.099 nM, respectively). In immature rats, oral administration of CHF 4227 for 3 days inhibited the uterotrophic action of 17alpha-ethynyl estradiol (EE2) (ED(50) = 0.016 mg/kg. day); raloxifene was 25 times less potent as estrogen antagonist (ED(50) = 0.39 mg/kg. day), whereas both compounds were found to be devoid of uterotrophic activity. In line with its estrogen antagonist effect, CHF 4227 significantly prevented the development of dimethylbenz[a]anthracene (DMBA)-induced mammary tumors, the incidence being reduced from 87.5 to 26.3% 6 months after DMBA administration. In ovariectomized (OVX) rats treated orally for 4 weeks, CHF 4227 completely inhibited OVX effects on bone density (ED(50) = 0.003 mg/kg. day) and on serum osteocalcin levels. The protective effects on bone were comparable with those achieved with EE2, whereas raloxifene was less efficacious and 100 times less potent. CHF 4227 reduced serum cholesterol (ED(50) = 0.007 mg/kg. day) and had little to no stimulatory effects on uterine weight, uterine peroxidase activity, and endometrium epithelial thickness. In conclusion, CHF 4227 compares favorably in efficacy and potency with raloxifene in preventing bone loss and in antagonizing EE2 stimulation of the uterus. This profile along with the minimal uterine stimulation suggests a therapeutic advantage to CHF 4227 over EE2 or raloxifene for the treatment of postmenopausal women.

Effects of 3-phenyl-4-[[4-[2-(1-piperidinyl)ethoxy]phenyl]methyl]- 2H-1-benzopyran-7-ol (CHF 4056), a novel nonsteroidal estrogen agonist/antagonist, on reproductive and nonreproductive tissue.

We have discovered a new, nonsteroidal, estrogen agonist/antagonist, 3-phenyl-4-[[4-[2-(1-piperidinyl)ethoxy]phenyl] methyl]-2H-1-benzopyran-7-ol (CHF 4056). The aim of this study was to determine the effects of CHF 4056 on a series of parameters (body weight, uteri, serum cholesterol, and bones) that were previously shown to be sensitive to estrogens and to selective estrogen receptor modulators (SERMs). CHF 4056 is a benzopyran derivative that binds with high affinity to the human estrogen receptors alpha and beta (dissociation constant K(i) of 0.041 and 0.157 nM, respectively). In immature rats, CHF 4056 induced a full estrogen antagonism (half-maximal efficacious dose = 0.33 mg/kg x day p.o.) coupled with a lack of uterine stimulatory activity, whereas the structurally related SERM levormeloxifene demonstrated a maximal partial agonist effect of approximately 65% that of 17alpha-ethynyl estradiol (EE2). In ovariectomized (OVX) rats, CHF 4056 (0.1-1 mg/kg x day p.o. for 4 weeks) significantly reduced OVX-induced bone loss in the lumbar spine L1-4 and OVX-induced increase in serum osteocalcin. These protective effects on bone tissue were comparable with those of 0.1 mg/kg x day EE2. In the same experimental conditions, serum cholesterol was significantly lower in the CHF 4056-treated animals, compared with vehicle-treated OVX rats. In line with the results observed in immature rats, also in OVX rats CHF 4056 diverged dramatically from EE2 and levormeloxifene in its lack of significant estrogenic effects on uterine tissue. In conclusion, CHF 4056 is a new SERM that produces beneficial effects on bone and cholesterol levels, while maintaining antagonist effects on the uterus.