The purpose of this first-in-human study is to evaluate safety and tolerability of ODM-209 and find the dose of ODM-209.

Part 1: to evaluate the safety and tolerability of ODM-209, to define the maximum tolerated dose (MTD) and dose limiting toxicities (DLTs) of ODM-209, if feasible, to define the recommended dose of ODM-209 and replacement therapy for Part 2 of the study.

Part 2: to further evaluate the safety and tolerability of ODM-209, to evaluate the preliminary anticancer activity of ODM-209.

MAIN INCLUSION CRITERIA:

• Written informed consent (IC) obtained.
• Age ≥ 18 years.
• ECOG performance status 0-1.
• Adequate marrow, liver and kidney function.
• Able to swallow study treatment.

Main Prostate cancer specific inclusion criteria:

• Histologically confirmed adenocarcinoma of the prostate.
• Castration resistant prostate cancer with serum testosterone < 50 ng/dl.
• Metastatic disease.
• Ongoing androgen deprivation therapy with GnRH analogue, or have had bilateral orchiectomy.
• Have had treatment with at least one line of second generation androgen receptor targeting therapy and one line of chemotherapy.

Main Breast cancer specific inclusion criteria:

• Histologically confirmed breast carcinoma
• ER positive, HER2-negative advanced breast cancer
• Postmenopausal or pre/perimenopausal if amendable to be treated with GnRH agonist or antagonist.
• Documented disease progression after treatment with at least 2 lines of systemic treatment for advanced breast cancer. Of these, at least one line must have been endocrine treatment in combination with a cdk4/6 inhibitor.

MAIN EXCLUSION CRITERIA

• History of pituitary dysfunction.
• Known brain metastases or active leptomeningeal disease.
• Active infection or other medical condition that would make corticosteroids contraindicated.
• Hypotension or uncontrolled hypertension.
• Clinically significant cardiovascular disease, e.g. myocardial infarction, arterial thrombotic events, or pulmonary embolism in the past six months, unstable angina, or congestive heart failure (New York Heart Association [NYHA] class II-IV).
• Prolonged QTcF interval.
• Use of any investigational drug 4 weeks prior to the start of the study treatment.