Orphagen has identified and characterized small molecule antagonists to steroidogenic factor-1 (SF-1). SF-1 binds to and regulates DNA promoter elements in the major transporters and enzymes required for adrenal steroid synthesis. It is also required for development of the adrenal gland. SF-1 antagonists inhibit cortisol secretion in adrenal cells and have potential application in two orphan indications, Cushing’s syndrome and adrenocortical carcinoma. In addition, SF-1 appears to have an important role in the progression of advanced prostate cancer.
An estimated 20,000 people in the US have Cushing’s, with more than 3,000 new cases diagnosed each year. The incidence is similar in Europe. Cushing’s syndrome disproportionately affects females, who make up about 75% of the diagnosed cases. Symptoms of Cushing’s syndrome can include obesity, diabetes, psychiatric disorders, osteoporosis and immune suppression. Cushing’s syndrome is caused by elevated secretion of cortisol from the adrenal gland, in association with pituitary, adrenal or other cancers.
Orphagen has identified small molecule antagonists to SF-1 that have the potential to suppress cortisol levels in all Cushing’s patients without serious side effects.
Adrenocortical carcinoma (ACC):
ACC is a rare malignancy with an extremely poor prognosis (5-year overall survival: 37-47%). Complete surgical resection offers hope for long-term survival but surgery is not an option in up to two-thirds of patients because metastasis has usually occurred by the time of diagnosis.
SF-1 is recognized as a potential mechanism-based therapeutic target for control of ACC and an SF-1 antagonist could be used in the treatment of ACC.
Pediatric ACC is a very rare but aggressive cancer with a long-term survival rate of about 50%. Approximately 60% of children with adrenocortical tumors are diagnosed before the age of four. The SF-1 gene is amplified and SF-1 protein is overexpressed in the vast majority of childhood adrenocortical tumors strongly implicating SF-1 in pediatric adrenocortical tumorigenesis.
Castration resistant prostate cancer (CRPC):
CRPC is the most common cancer in males. Surgery is not an option if the cancer has spread beyond the prostate gland, at which point patients typically receive hormonal therapy, essentially chemical castration. This course of therapy usually fails within two years, resulting in castration resistant prostate cancer (CRPC). Most patients eventually succumb to CRPC, which is the second leading cause of cancer deaths in men.
SF-1 antagonists may: (1) block the adrenal androgens that circumvent chemical castration, and are a primary cause of CRPC; and (2) inhibit synthesis of androgens within the prostate tumor itself, where SF-1 may control induction of enzymes for de novo androgen synthesis in treatment-resistant cancers.