Lasofoxifene Tartrate

**Semantic type:** Pharmacologic Substance

**Definition:** The tartrate salt form of lasofoxifene, a non-steroidal, naphthalene-derived, third-generation selective estrogen receptor modulator (SERM) with potential antineoplastic and anti-osteoporotic activities. Upon oral administration, lasofoxifene selectively binds to both estrogen receptor alpha (ERalpha; ESR1) and estrogen receptor beta (ERbeta; ESR2) with high affinity and mimics the effects of endogenous estradiol with varying agonist and antagonist effects in ER-expressing tissues. Blockade of ERalpha by lasofoxifene may potentially inhibit estrogen-dependent cancer cell proliferation in ER-expressing cancers. Lasofoxifene may also bind to the certain mutant forms of ERalpha, including the Y537S ESR1 mutant, making it potentially useful in the treatment of tumors that have acquired resistance to other ER-targeting agents.

**Synonyms:** - (-)-cis-5,6,7,8-Tetrahydro-6-phenyl-5-(p-(2-(1-pyrrolidinyl)ethoxy)phenyl)-2-naphthol D-tartrate (1:1) (salt) - CB 336156EB - Fablyn - LASOFOXIFENE TARTRATE