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Sermonix Pharmaceuticals Begins Phase II Lasofoxifene Breast Cancer Trial

NEW YORK – Sermonix Pharmaceuticals announced on Tuesday that it had dosed the first patient in a Phase II clinical trial of its investigational drug, lasofoxifene, in combination with CDK 4/6 inhibitor abemaciclib (Eli Lilly's Verzenio).

The trial, called ELAINE 2, will evaluate lasofoxifene, a selective estrogen receptor modulator, in combination with abemaciclib in pre- and postmenopausal women with locally advanced, metastatic, estrogen receptor-positive, HER2-negative breast cancer and an ESR1 mutation in their tumors. The primary endpoint is progression-free survival.

Columbus, Ohio-based Sermonix is partnering with molecular diagnostics firm Tempus, which will test patients for ESR1 mutations and determine their eligibility for the trial.

Earlier studies showed lasofoxifene's activity in cancers with estrogen receptor mutations, which could be promising for patients who have acquired endocrine resistance due to ESR1 mutations. The drug's activity in ESR1 mutations was discovered at Duke University.

"Combination therapy with a CDK 4/6 inhibitor and an endocrine backbone will likely continue to be widely utilized for women with metastatic breast cancer, and our positive preclinical data encouraged us to pursue further safety data with a lasofoxifene and abemaciclib combination in collaboration with Eli Lilly," Paul Plourde, Sermonix's VP of clinical development, said in a statement. "It's an important step toward conducting a larger study, so we are pleased to be in the clinic, continuing our research and our momentum."

Sermonix licensed the investigational drug globally from Ligand Pharmaceuticals, which studied the drug in non-oncology indications. Last year, Sermonix began enrolling patients into the ELAINE 1 study, in which it is comparing oral lasofoxifene against intramuscular fulvestrant for the treatment of postmenopausal women with locally advanced or metastatic, estrogen receptor-positive, HER2-negative, ESR1-mutated breast cancer.