Sermonix Poster Presentation at 2019 ASCO Annual Meeting Demonstrates Promise for Lasofoxifene in Treating ER+ Metastatic Breast Cancer Patients With ESR1 Mutations

Sermonix-sponsored University of Chicago preclinical investigation demonstrated:

  • Lasofoxifene alone was significantly more effective than fulvestrant at inhibiting metastasis of both MCF7-Y537S and D538G tumors to the lungs and liver.
  • Lasofoxifene, in combination with palbociclib, was more effective than fulvestrant + palbociclib at reducing primary tumor growth.
  • Lasofoxifene + palbociclib was more effective at inhibiting liver metastasis than either drug alone and was more effective than fulvestrant + palbociclib at reducing metastasis to the liver and lungs.

COLUMBUS, Ohio, June 03, 2019 (GLOBE NEWSWIRE) — Sermonix Pharmaceuticals LLC, a privately held biopharmaceutical company focused on the development of female-specific oncology products in the precision medicine metastatic breast cancer arena, yesterday presented a poster on the preclinical performance of its lead investigational drug, lasofoxifene, at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting. The new abstract showed that lasofoxifene, in combination with palbociclib, was more effective than the combination of fulvestrant and palbociclib at reducing primary tumor growth in a mouse intraductal model.

The results of the abstract titled “Lasofoxifene as a Potential Treatment for ER+ Metastatic Breast Cancer” also demonstrated that:

  • Lasofoxifene alone was significantly more effective than fulvestrant at inhibiting metastasis of both MCF7-Y537S and D538G tumors to the lungs and liver.
  • Lasofoxifene + palbociclib was more effective at inhibiting liver metastasis than either drug alone and was more effective than fulvestrant + palbociclib at reducing metastasis to the liver and lungs.

For patients with estrogen receptor-positive (ER+) metastatic breast cancer, fulvestrant is a current approved first line treatment alone and in combination with ribiciclib, and in combination with palbociclib and abemaciclib with disease progression after endocrine therapy. ER+ metastatic breast cancers that express constitutively active somatic ESR1 mutations at Y537S and D538G appear to allow many tumors to progress rapidly, even on currently available endocrine therapies.

Sermonix, which is currently enrolling patients in a Phase 2 clinical study of lasofoxifene in ER+ metastatic breast cancer, last month was granted a Fast Track designation by the U.S. Food and Drug Administration for lasofoxifene in advanced breast cancer with ESR1 mutations. The designation allows for the expedited development and review of drugs that treat serious conditions and fill an unmet medical need.

“The data, from Dr. Geoffrey Greene’s lab at the University of Chicago, demonstrate that lasofoxifene, alone and in combination with a CDK4/6 inhibitor, has potential promise for treating endocrine therapy resistant ER+ metastatic breast cancer in patients whose tumors express activating ESR1 mutations,” said Dr. Barry Komm, Sermonix chief scientific officer.

Sermonix’s Phase 2 open-label, randomized, multi-center Evaluation of Lasofoxifene in ESR1 Mutations (ELAINE) study will assess the activity of oral lasofoxifene versus intramuscular fulvestrant for the treatment of postmenopausal women who have locally advanced or metastatic ER+/HER2- breast cancer with an ESR1 mutation identified by a liquid biopsy.

About Lasofoxifene

Lasofoxifene is an investigational, nonsteroidal selective estrogen receptor modulator (SERM), which Sermonix licensed from Ligand Pharmaceuticals Inc. and has been studied in previous comprehensive Phase 1-3 non-oncology clinical trials in more than 15,000 postmenopausal women worldwide. Lasofoxifene’s bioavailability and activity in mutations of the estrogen receptor could potentially hold promise for patients who have acquired endocrine resistance and ESR1 mutations, a common mutation in the metastatic setting and an area of high unmet medical need. Lasofoxifene’s novel activity in ESR1 mutations was recently discovered and Sermonix has exclusive rights to develop and commercialize it in this area. A potent, well-characterized SERM, lasofoxifene, if approved, could play a critical role in the targeted precision medicine treatment of advanced ER+ breast cancer.

About Sermonix

Sermonix Pharmaceuticals LLC is a biopharmaceutical company with a targeted focus on bringing female-specific oncology products through proof of concept, preclinical and clinical development, and regulatory approval. The company was founded in 2014 by David Portman, M.D., a leading clinical researcher and expert in women’s health, menopause and selective estrogen receptor modulator (SERM) therapy. Sermonix’s lead product is oral lasofoxifene. The Sermonix management team, led by Dr. Portman, has significant experience in all stages of the drug development and regulatory process. Paul Plourde, M.D., vice president of oncology clinical development, was previously with AstraZeneca, where he was instrumental in the development and approval of tamoxifen, Arimidex® and Faslodex®. Barry Komm, Ph.D., chief scientific officer, is former head of the SERM program at Wyeth and Pfizer, playing a key role in the development and approval of bazedoxifene and Duavee®. Elizabeth Attias, M.M.Sc., Sc.D., vice president of business development, has extensive experience in pharmaceutical drug commercialization. Simon Jenkins, Ph.D. vice president of operations, has over 30 years of experience in global drug development leadership roles at Wyeth and Pfizer across a range of therapeutic areas. Sermonix non-executive chairman of the board is Anthony Wild, Ph.D., former president of both Parke-Davis Pharmaceuticals and Warner-Lambert’s Pharmaceutical Division. Learn more at https://sermonixpharma.com/.