ACER-801 (osanetant) for induced vasomotor symptoms (iVMS)


Hot flashes, flushing, and night sweats are known as vasomotor symptoms (VMS), and most often occur in women who are entering or in menopause. VMS are causally related to decreasing estradiol concentrations, mainly in the serum and subsequently also in the temperature regulating center located in the hypothalamus. The lack of estrogen alters neurotransmitter activity, especially in the serotonergic and noradrenergic pathways.

VMS that are induced by either chemical or surgical intervention are referred to as induced vasomotor symptoms (iVMS). For example, patients receiving tamoxifen treatment for breast cancer, men receiving leuprolide treatment for prostate cancer, and women who are BRCA-positive who elect to have bilateral salpingo-oophorectomy (BSO)1,2 may experience severe iVMS.

ACER-801 is a selective, non-peptide tachykinin NK3 receptor antagonist. NK3R is the main receptor for neurokinin B (NKB), a tachykinin peptide primarily found in the arcuate nucleus (ARC) of the hypothalamus. In December 2018, we entered into an exclusive license agreement with Sanofi to acquire worldwide rights to osanetant. We believe that several disorders involving the hypothalamus-pituitary-gonadal axis could benefit from treatment with an NK3R antagonist. ACER-801, if approved for marketing by the FDA, would qualify as an NCE in the U.S., and as such, would be eligible for five years of market exclusivity following potential FDA approval. Additional exclusivity would depend on the indications selected and the development pathway that is chosen.

We submitted an IND with the FDA in the fourth quarter of 2021 for the treatment of VMS. A Phase 2a clinical trial initiation is expected in Q1 2022 designed to evaluate ACER-801’s PK, efficacy and safety in postmenopausal women and to identify the optimal dosing strategy for subsequent efficacy studies in certain cancer patients with iVMS, dependent upon successful IND submission and clearance, and subject to additional capital. Additional information on the osanetant program can be found in our current corporate presentation.

ACER-801 is an investigational drug in the U.S. and is not currently FDA approved for any indication.


  1. Kotsopoulos J, Huzarski T, Gronwald J, Moller P, Lynch HT, Neuhausen SL, et al. Hormone replacement therapy after menopause and risk of breast cancer in BRCA1 mutation carriers: a case-control study. Breast Cancer Research and Treatment 2016;155(2):365–73.
  2. Guidozzi F. Hormone therapy after prophylactic risk-reducing bilateral salpingo-oophorectomy in women who have BRCA gene mutation. Climacteric 2016;19(5): 419–22.