This trial will have two screening visits over about a month with tests to assess if subjects are eligible to start study therapy. Once subjects have completed screening, and if they are determined to be eligible, they will be randomized to receive one of three oral daily doses of LUM-201 or daily injections of recombinant human growth hormone (rhGH). All subjects will have an equal chance of being placed in any of the four groups.

The trial consists of 6 months of treatment. After screening, subjects will return to clinic for 5 visits. At each clinic visit subjects will have a physical exam, blood and urine collections. There will also be 3 phone calls with study staff that will take place between the clinic visits.

Inclusion Criteria:

• Have an established diagnosis of PGHD as determined by standard diagnostic criteria. Eligible subjects must be naïve-to-treatment and be prepubertal.
• Peak cortisol > 20 µg/dL on a glucagon, ACTH or insulin test.
• At Screening, be ≥ 3.0 years and < 10.0 years for girls and < 11.0 years for boys.
• Have HT-SDS < -2.0.
• Have a bone age examination at Screening or within the 6 months prior to Screening that, in the interpretation of the Investigator, is delayed with respect to chronological age.
• Have prepubertal status as evidenced by Tanner Stage I breast development in girls and testicular volume < 4.0 mL in boys.
• In girls, have genetic testing results to rule out Turner syndrome. If SHOX genetic testing results are available, they need to be negative.
• Have normal thyroid function. Subjects diagnosed with hypothyroidism must have documented successful treatment for at least 30 days prior to Day 1.

Exclusion Criteria:

• Any medical or genetic condition which, in the opinion of the Investigator or Medical Monitor (MM), can be an independent cause of short stature and/or limit the response to exogenous growth factor treatment. (Examples: diabetes, named syndromes).
• A medical or genetic condition that, in the opinion of the Investigator and/or MM, adds unwarranted risk to use of LUM-201 or rhGH.
• Use of any medication that, in the opinion of the Investigator and/or MM, can independently cause short stature or limit the response to exogenous growth factors (Example: glucocorticoids).
• Evidence or history of an intracranial mass (e.g., pituitary tumor, craniopharyngioma).
• Suspicion of absent pituitary function as evidenced by a maximal stimulated GH ≤ 3 ng/mL or pituitary deficiencies beyond GH and thyroid function.
• Malnutrition as evidenced by medical history or a body weight < 5th percentile for current height.
• BMI > 95th percentile.
• Gestational age-adjusted birth weight < 5th percentile (small for gestational age).
• History of spinal, cranial, or total body irradiation.
• A diagnosis of Attention Deficit Hyperactivity Disorder (ADHD) and/or use of medications to treat ADHD.