The purpose of this study is to evaluate the effects on serum testosterone (ST) after 6
weeks of subcutaneous (SC) administration of different doses and dosing frequencies of
TAK-448 to middle-aged and older men with low ST levels.
The drug being tested in this study is called TAK-448. TAK-448 is being tested to define a
dose and dose frequency which results in a clinically relevant improvement in ST in
middle-aged and older men with low ST levels. This study will look at ST levels in men who
The study will enroll approximately 66 participants. Two Cohorts are planned for this study.
Cohort 1 will include 3 dose groups that will run in parallel and consist of the following
SC doses, 0.1 mcg once-daily, 0.3 mcg twice-weekly, and 1.0 mcg once-weekly for a period of
6 weeks. Within each dose group in Cohort 1, 11 participants will be enrolled and assigned
so that 8 will receive TAK-448 and 3 will receive placebo. Cohort 2 will be enrolled after
the completion of Cohort 1 and may include up to 3 dose groups. The dose and dosing
frequency will be decided based on results from Cohort 1.
This single-center trial will be conducted in the United States. The overall time to
participate in this study is up to 16 weeks. Participants will make daily visits to the
clinic for 8 weeks, and will be contacted by telephone 14 days after last dose of study drug
for a follow-up assessment.
1. Has total ST levels less than 300 nanograms per deciliter (ng/dL) at 2 separate time
points during Screening.
2. Has a body mass index (BMI) between 20.0 and 40.0 kilogram per square meter (kg/m^2),
inclusive at Screening.
3. A male participant who is nonsterilized and sexually active with a female partner of
childbearing potential agrees to use adequate contraception from the time of signing
of informed consent throughout the duration of the study and for 12 weeks after the
1. Has uncontrolled, clinically significant neurologic, cardiovascular, pulmonary,
hepatic, renal, metabolic, gastrointestinal, or endocrine disease or other
abnormality that may impact the ability of the participant to participate or
potentially confound the study results. Participants will be excluded based on:
1. Has a serum creatinine greater than (>) 2.0 milligrams per deciliter (mg/dL) at
2. Is receiving dialysis treatment.
3. Has an American Urological Association (AUA)/ International Prostate Symptom
Score (I-PSS) score of >19 or serum prostate-specific antigen (PSA) >4 nanogram
per milliliter (ng/mL) at Screening.
4. Has thyrotropin (TSH) levels less than (<) 0.3 or >7.5 milli-international units
per liter (mIU/L) at Screening.
5. Has systolic blood pressure >160 millimeter of mercury (mm Hg) or diastolic
blood pressure >100 mm Hg (if out of range may be repeated once for eligibility
determination) at Screening.
6. Has luteinizing hormone (LH) >9.4 units per liter (U/L) at Screening.
7. Is receiving insulin therapy.
8. Has a hematocrit <30 percent (%) or >48% at Screening.
9. Has a glycosylated hemoglobin (HbA1c) >8.0 at Screening (Cohort 1).
2. Has type 2 diabetes mellitus defined as fasting blood glucose >125 mg/dL, HbA1c
>6.2%, or use of antidiabetic medication (Cohort 2 only).
3. Has clinical evidence of anatomic or pathological hypothalamic/pituitary/testicular
disease, such as (but not limited to) Klinefelter's syndrome, Kallmann's syndrome,
systemic infiltrative diseases (hemochromatosis, sarcoidosis, Wilson's disease), or
prior pituitary surgery.
4. Has used gonadotropin-releasing hormone (GnRH) agonists, GnRH antagonists,
antiandrogens, clomiphene, or other reproductive hormone-related agents within 6
months prior to Screening.
5. Has used anabolic therapies (testosterone, dehydroepiandrosterone [DHEA],
androstendione, any other androgen, or recombinant human growth hormone) within 1
year of Screening.