Sermonix Pharmaceuticals shares details of the first-ever known complete and durable clinical response in a patient with ER+/HER2- metastatic breast cancer with an ESR1 mutation after prior treatment with a CDK4/6 inhibitor via a hormonal regimen unique

Sermonix Pharmaceuticals Inc.

  • Presentation given at the Ninth Annual Metastatic Breast Cancer Research Conference in Park City, Utah

  • One case has been reported during a phase 2 study investigating the efficacy of lasofoxifene, Sermonix’s lead investigational drug

COLUMBUS, Ohio, Sept. 14, 2022 (GLOBE NEWSWIRE) — Sermonix Pharmaceuticals Inc., a private biopharmaceutical company developing innovative therapies to specifically treat ESR1-mutated metastatic breast and gynecological cancers, has widely shared a case report detailing the first-ever known discovery of a durable complete response that could be characterized as complete clinical remission in a patient with metastatic estrogen receptor positive (ER+)/HER2- breast cancer with an ESR1 mutation after prior therapy by a CDK4/6 inhibitor when participating in any single hormone based therapy.

The case report, “Durable complete remission of ER+/HER2- metastatic breast cancer after treatment with lasofoxifenewas originally shared Sept. 9 at the Ninth Annual Metastatic Breast Cancer Research Conference in Park City, Utah. Lasofoxifene is Sermonix’s lead investigational drug.

Durable Complete Response (CR) was reported in Sermonix Phase 2 Eevaluation of ThesofoxIdonote in ESR1 mutations (ELAINE 1, NCT03781063) study. The open-label, randomized study evaluated the efficacy of oral lasofoxifene versus intramuscular fulvestrant for the treatment of postmenopausal women with locally advanced or metastatic ER+/HER2- breast cancer with an ESR1 mutation and progression-free survival as primary endpoint. Breakthrough data from ELAINE 1 was presented on September 10 at the 2022 European Society for Medical Oncology (ESMO) Congress in Paris. Although not statistically significant, the study results numerically favored lasofoxifene.

The patient was recruited into the ELAINE 1 study and started treatment on December 16, 2020. Her first radiological assessment, eight weeks after initiation of lasofoxifene by PET-FDG, revealed no pathological uptake in her pleural lesions , a total diameter of 14 mm (55% reduction) and significant reduction of the iliac bone lesion with no new pathological findings. CT scans at week 16 revealed further improvement until radiological complete disappearance of all measurable and non-measurable lesions. Complete radiological response was maintained at 80 weeks (June 29, 2022).

“Achieving a complete response in metastatic breast cancer with post-CDK4/6 inhibitor endocrine therapy is extremely rare, especially with single-agent endocrine therapy,” said Dr. Einav Nili Gal-Yam. , MD, Ph.D., Principal Investigator of ELAINE 1 and Head of the Breast Oncology Institute at Chaim Sheba Medical Center in Ramat Gan, Israel. “This is a very gratifying result, underscoring the potentially important role of lasofoxifene in addressing the unmet needs of patients with ESR1 mutations. We look forward to the continued clinical development of this drug. »

About lasofoxifene
Lasofoxifene is an investigational non-steroidal Selective Estrogen Receptor Modulator (SERM) licensed worldwide by Sermonix from Ligand Pharmaceuticals Inc. (NASDAQ:LGND) and has been studied in comprehensive non-oncology clinical trials phase 1 to 3 earlier in more than 15,000 postmenopausal women. worldwide. The bioavailability and activity of lasofoxifene in estrogen receptor mutations 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 ​​unmet medical need. are high. The novel activity of lasofoxifene in ESR1 mutations was discovered at Duke University and Sermonix holds the exclusive rights to develop and commercialize the product in this area. Lasofoxifene, a potent oral SERM, could, if approved, play a critical role in precision medicine-targeted treatment of advanced ER+ breast cancer.

About Sermonix
Sermonix Pharmaceuticals Inc. is a private biopharmaceutical company focused on the development of women-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, MD, a leading clinical researcher and expert in women’s health, menopause, and Selective Estrogen Receptor Modulator (SERM) therapy. Sermonix’s management team, led by Dr. Portman, has extensive experience at all stages of the drug development and regulatory process. Paul Plourde, MD, Vice President of Clinical Development in Oncology, has decades of experience in the field of oncology drug development. Barry Komm, Ph.D., Scientific Director, is recognized for his expertise in SERM biology. Miriam Portman, MD, is chief operating officer. Elizabeth Attias, MMSc., Sc.D., Director of Strategy and Development, has extensive experience in the commercialization of pharmaceutical drugs. Simon Jenkins, Ph.D., Vice President of Operations, has more than 30 years of experience in global drug development leadership. The non-executive chairman of Sermonix’s board of directors is Anthony Wild, Ph.D., former chairman of Parke-Davis Pharmaceuticals and the pharmaceutical division of Warner-Lambert. Learn more at

Contact information:
Glenn Garmont
LifeSci Advisors
Managing Director, Investor Relations, Corporate Communications
[email protected]

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