Sermonix Pharmaceuticals Shares Additional Findings From Its ELAINE 1 Clinical Study at the 4th Annual Congress of the International Society of Liquid Biopsy

COLUMBUS, Ohio, Oct. 21, 2022 (GLOBE NEWSWIRE) -- Sermonix Pharmaceuticals Inc., a privately held biopharmaceutical company developing innovative therapeutics to specifically treat ESR1-mutated metastatic breast and gynecological cancers, today shared additional findings from its Evaluation of Lasofoxifene in ESR1 Mutations (ELAINE 1) Phase 2 study during the 4^th Annual Congress of the International Society of Liquid Biopsy (ISLB) in Miami.Initial results from the open-label (NCT03781063) study assessing the efficacy and safety of Sermonix’s lead development candidate, oral lasofoxifene, versus the current standard of care, intramuscular fulvestrant, in postmenopausal women with locally advanced or metastatic ER+/HER2- breast cancer (mBC) and an ESR1 mutation were shared last month.

Sermonix’s ISLB poster, “Lasofoxifene Reduced ESR1 Mutant Allele Fraction and Provided Clinical Benefit Versus Fulvestrant in Metastatic Breast Cancer: the ELAINE 1 Trial,” explored a potential predictive clinical role of high ESR1 mutation levels. Investigators evaluated mutant allele fraction (MAF) ctDNA dynamics following treatment with lasofoxifene or fulvestrant. The primary endpoint was progression free survival (PFS). Clinical benefit rate (CBR) was also assessed.

“In our analysis of the data from the ELAINE 1 study, lasofoxifene decreased ESR1-mutant expression and efficacy results numerically favored lasofoxifene, independent of baseline MAF,” said Massimo Cristofanilli, M.D., past president of the International Society of Liquid Biopsy (ISLB) and poster co-author. “Future, larger trials are necessary to confirm a predictive role of ESR1-mutant MAF in selecting endocrine therapies.”

*Results highlights:*

· PFS and CBR were 6.04 months and 37% for lasofoxifene versus 4.04 months and 22% for fulvestrant, respectively. Although not statistically significant, all clinical endpoints numerically favored lasofoxifene.Additional exploratory analyses included in the poster, not-pre-specified:

· Lasofoxifene decreased MAF in 85% (58/68) of ESR1 variants at 8 weeks from baseline, while fulvestrant decreased MAF in 49% (30/61)
· With baseline overall MAF ≥2%, lasofoxifene decreased 89% (16/18) and fulvestrant decreased 29% (5/17); with Y537S ≥2%, lasofoxifene decreased 80% (4/5) and fulvestrant decreased 14% (1/7)
· With a MAF ≥13%, no fulvestrant-treated patients (0/5) achieved a CBR, whereas CBR with lasofoxifene was 38% (3/8)“The results of our ELAINE 1 study provide very strong rationale for continued development of lasofoxifene for a large subset of breast cancer patients – those with an ESR1 mutation – who are increasingly resistant to endocrine therapies such as aromatase inhibitors, resulting in a poor prognosis,” said Dr. David Portman, founder and chief executive officer of Sermonix, and co-author of the poster. “In this exploratory analysis, lasofoxifene compared to fulvestrant decreased ESR1 mutant ctDNA regardless of baseline MAF. Liquid biopsy ctDNA technology will continue to be used in future lasofoxifene studies to further explore these intriguing findings, and we anticipate further validating the value of ctDNA in a large, Phase 3 registrational study, which we are planning to initiate in the first quarter of 2023.”

*About Lasofoxifene*
Lasofoxifene is an investigational, nonsteroidal selective estrogen receptor modulator (SERM), which Sermonix licensed globally from Ligand Pharmaceuticals Inc. (NASDAQ: LGND) 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 due to ESR1 mutations, a common finding in the metastatic setting and an area of high unmet medical need. Lasofoxifene’s novel activity in ESR1 mutations was discovered at Duke University and Sermonix has exclusive rights to develop and commercialize the product in this area. Lasofoxifene, a potent, oral SERM could, if approved, play a critical role in the targeted precision medicine treatment of advanced ER+ breast cancer.

*About Sermonix*
Sermonix Pharmaceuticals Inc. is a privately held biopharmaceutical company focused on the development of female-specific oncology products and is currently undertaking two Phase 2 clinical studies of lasofoxifene, its lead investigational drug. Sermonix Pharmaceuticals 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. 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, has many decades of experience in the oncology drug development arena. Barry Komm, Ph.D., chief scientific officer, is recognized for his expertise in SERM biology. Miriam Portman, M.D., is chief operating officer. Elizabeth Attias, M.M.Sc., Sc.D., chief strategy and development officer, 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. 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 SermonixPharma.com.

*Contact information:*
Glenn Garmont
LifeSci Advisors
Managing Director, Investor Relations Corporate Communications
ggarmont@lifesciadvisors.com
646-876-5521