Lasofoxifene, sold under the brand name Fablyn, is a nonsteroidal

selective estrogen receptor modulator Selective estrogen receptor modulators (SERMs), also known as estrogen receptor agonist/antagonists (ERAAs), are a class of drugs that act on the estrogen receptor (ER). A characteristic that distinguishes these substances from pure ER agonists a ...

(SERM) which is marketed by

Pfizer Pfizer Inc. ( ) is an American multinational pharmaceutical and biotechnology corporation headquartered on 42nd Street in Manhattan, New York City. The company was established in 1849 in New York by two German entrepreneurs, Charles Pfizer ...

Lithuania Lithuania (; lt, Lietuva ), officially the Republic of Lithuania ( lt, Lietuvos Respublika, links=no ), is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea. Lithuania ...

and

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

for the prevention and treatment of

osteoporosis Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to bone fragility, and consequent increase in fracture risk. It is the most common reason for a broken bone ...

and for the treatment of

vaginal atrophy Atrophic vaginitis is inflammation of the vagina as a result of tissue thinning due to not enough estrogen. Symptoms may include pain with sex, vaginal itchiness or dryness, and an urge to urinate or burning with urination. It generally does no ...

, and the result of an exclusive research collaboration with

Ligand Pharmaceuticals Ligand Pharmaceuticals is a biopharmaceutical company located in San Diego, California. Founded in 1987 as Progenix Inc., the company went public in 1992. Initially focused on developing its own drugs, a period of turbulence in the early 2000s cul ...

(LGND). It also appears to have had a statistically significant effect of reducing

breast cancer Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or a re ...

in women according to a study published in The Journal of the National Cancer Institute.

Medical uses

Osteoporosis

In postmenopausal women with osteoporosis, lasofoxifene at a dose of 0.5 mg per day was associated with reduced risks of nonvertebral and vertebral fractures, ER-positive breast cancer, coronary heart disease, and stroke but an increased risk of venous thromboembolic events.

Breast cancer

In studies of breast cancer prevention, lasofoxifene showed a 79% reduction in breast cancer incidence and an 83% reduction specific incidence of estrogen receptor-positive breast cancers, which is significantly higher than reductions found with the related SERMs

tamoxifen Tamoxifen, sold under the brand name Nolvadex among others, is a selective estrogen receptor modulator used to prevent breast cancer in women and treat breast cancer in women and men. It is also being studied for other types of cancer. It has b ...

and raloxifene. In accordance, a

network meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting me ...

of SERMs for breast cancer prevention found the highest reduction in risk with lasofoxifene of all the drugs. The reduction was even greater than that observed with aromatase inhibitors, which have generally been found to confer a greater risk reduction than SERMs. It also has shown promise in

ESR1 Estrogen receptor alpha (ERα), also known as NR3A1 (nuclear receptor subfamily 3, group A, member 1), is one of two main types of estrogen receptor, a nuclear receptor (mainly found as a chromatin-binding protein) that is activated by the sex h ...

mutant patients with 'approximately 40% of patients harboring this mutation'.

Pharmacology

Pharmacodynamics

Lasofoxifene selectively binds to both

ERα Estrogen receptor alpha (ERα), also known as NR3A1 (nuclear receptor subfamily 3, group A, member 1), is one of two main types of estrogen receptor, a nuclear receptor (mainly found as a chromatin-binding protein) that is activated by the sex ...

and

ERβ Estrogen receptor beta (ERβ) also known as NR3A2 (nuclear receptor subfamily 3, group A, member 2) is one of two main types of estrogen receptor—a nuclear receptor which is activated by the sex hormone estrogen. In humans ERβ is encoded by ...

with high

affinity Affinity may refer to: Commerce, finance and law * Affinity (law), kinship by marriage * Affinity analysis, a market research and business management technique * Affinity Credit Union, a Saskatchewan-based credit union * Affinity Equity Partn ...

. Its IC₅₀ for ERα (1.5 nM) is similar to that of estradiol (4.8 nM) and is at least 10-fold higher than those of tamoxifen and raloxifene.

Pharmacokinetics

Lasofoxifene has greatly improved

oral The word oral may refer to: Relating to the mouth * Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid **Oral administration of medicines ** Oral examination (also known as an oral exam or oral ...

bioavailability relative to tamoxifen and raloxifene, and this may also be involved in its greater potency.

Chemistry

Lasofoxifene is a

naphthalene Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromati ...

derivative and a desmethyl dihydro analogue of

nafoxidine Nafoxidine (; developmental code names U-11,000A) or nafoxidine hydrochloride () is a nonsteroidal selective estrogen receptor modulator (SERM) or partial antiestrogen of the triphenylethylene group that was developed for the treatment of adv ...

History

In September 2005,

received a

non-approvable letter Approvable letters, and the related non-approvable letters (alternately not-approvable letters), were notifications sent out by the Food and Drug Administration (FDA) to drug manufacturers alerting them to the approval prospects of their drugs unde ...

from the U.S.

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...

regarding lasofoxifene (trade name Oporia), a selective estrogen receptor modulator for the prevention of osteoporosis. In January 2008, Ligand Pharmaceuticals, through its marketing partner,

, submitted a New Drug Application for lasofoxifene, which is expected to be marketed under the tradename Fablyn. Lasofoxifene was approved in the EU under the brand name Fablyn by the EMEA in March 2009.

Research

Lasofoxifene is under development by Sermonix Pharmaceuticals for the treatment of metastatic breast cancer and

dyspareunia Dyspareunia ( ) is painful sexual intercourse due to medical or psychological causes. The term ''dyspareunia'' covers both female dyspareunia and male dyspareunia, but many discussions that use the term without further specification concern the f ...

associated with

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

and

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

. It is also being researched for the potential treatment of

ovarian cancer Ovarian cancer is a cancerous tumor of an ovary. It may originate from the ovary itself or more commonly from communicating nearby structures such as fallopian tubes or the inner lining of the abdomen. The ovary is made up of three different c ...

. As of December 2017, lasofoxifene is in phase III

clinical trial Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, dietar ...

s for breast cancer and

phase II Phase II, Phase 2 or Phase Two may refer to: Media * Marvel Cinematic Universe: Phase Two, six American superhero films from 2013–2015 * ''Star Trek: Phase II'', an unrealized television series based on the characters of Gene Roddenberry's ''S ...

clinical studies for dyspareunia.

References

External links

Lasofoxifene - AdisInsight
* {{Other sex hormones and modulators of the genital system Hormonal antineoplastic drugs Phenol ethers Phenols Pyrrolidines Tetralins Selective estrogen receptor modulators