Open-label Extension Study to Evaluate the Safety of Long-term Twice-monthly Administration of Somavaratan in Adult Growth Hormone Deficiency (AGHD)

Inclusion Criteria: * Female participants of childbearing potential must have negative pregnancy test and use appropriate contraceptive methods * Documented GHD during adulthood * Participants naive to somavaratan must have an IGF-1 SDS value ≤ 0 at Screening * Participants taking other hormone replacement therapy must have been on a stable course of treatment for at least 3 months * Underlying disorders responsible for the participant's GHD must have been clinically stable for at least 6 months * Participants receiving daily rhGH injections must washout for ≥ 14 days * Body mass index (BMI) (kilograms \[kg\]/meter square \[m\^2\]) between 18.0 and 40.0 Exclusion Criteria: * Untreated adrenal insufficiency * Recently diagnosed thyroid dysfunction which is not being treated or has not been stable on therapy for at least 3 months * Currently taking anti-inflammatory dose of glucocorticoids that could potentially compromise safety or efficacy assessments * Currently taking a GHRH or IGF-I product * Current significant cardiovascular disease, heart insufficiency of New York Heart Association (NYHA) class \> 2 * Current significant disease thought to increase risk of receiving growth hormone or confound assessment of study outcomes * History of diabetes mellitus or inadequate glucose control * Current drug or alcohol abuse * Current human immunodeficiency virus (HIV) wasting syndrome (HIV testing not required) * History of malignancy in adulthood (participants with a history of childhood malignancy that were subsequently treated with rhGH in childhood and remain GHD in adulthood may be enrolled) * Women who are pregnant or breastfeeding * Treatment with an investigational drug other than somavaratan within 30 days prior to Screening * A significant abnormality in Screening laboratory results