PK and PD Study of LUM-201 in Children With Idiopathic Growth Hormone Deficiency: (OraGrowtH212)

Inclusion Criteria: * Have a chronological age ≥ 4.0 years and ≤ 10.0 years for girls and ≤ 12.0 years for boys. * Have a minimum body weight of 16 kg at the time of screening. * Have a bone age examination at screening or within the 6 months prior to screening that is delayed with respect to chronological age. Bone age should be based on the apparent BA of the proximal and distal phalanges, as opposed to the metacarpals, carpals and distal forearm. A central BA reader will make the final determination on BA eligibility. * Have HT-SDS ≤ -2.0 or a HT-SDS ≥ 2 SD below mean parental HT-SDS. If the other data (slow HV, low IGF-1, peak GH \< 10, and 6-month BA delay) are all consistent with idiopathic GHD, the subject may be enrolled with a height SDS \> -2.0 after consultation with the MMs. * Have an accurate baseline height velocity ≤ 5.5 cm/year based on at least 6-months of growth, if available * Within the past 6 months have a maximal GH response \> 3 and \< 10 ng/mL from at least one prior GH stimulation test within the past 6 months * Have prepubertal status as evidenced by Tanner Stage I breast development in girls and testicular volume \< 4.0 mL in boys. * Have an arm span to height ratio \> 96.5% * 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 the Baseline visit. Exclusion Criteria: * Any medical or genetic condition which, in the opinion of the PI or Medical Monitor (MM), can be an independent cause of short stature and/or limit the response to exogenous growth factor treatment (e.g., diabetes, , idiopathic short stature (ISS), SHOX-deficiency, skeletal dysplasia, constitutional growth delay, SGA, other). * A medical or genetic condition that, in the opinion of the PI and/or MM, adds unwarranted risk to use of LUM-201 (e.g., scoliosis). * Use of any medication that, in the opinion of the PI and/or MM, can independently cause short stature or limit the response to exogenous growth factors (e.g., glucocorticoids). * Evidence or history of an intracranial mass (e.g., pituitary tumor, craniopharyngioma). * Prior treatment with growth factors including, but not limited to, GH, IGF-1, and GH secretagogues. (These may be used for limited times as a diagnostic test.) * Suspicion of absence of pituitary function as evidenced by a maximal stimulated GH ≤ 3 ng/mL or pituitary hormone deficiencies beyond GH and thyroid function or a diagnosis of Organic PGHD. * At birth, gestational age \< 36.0 weeks. * Participation in any therapeutic trial of investigational drug(s) within the prior 6 months. * History of spinal, cranial or total body irradiation. * Recent commencement of non-stimulant therapy to treat attention deficit hyperactivity disorder (ADHD).