Somapacitan

A once-weekly recombinant human growth hormone derivative, the 191-residue hGH protein carrying a single albumin-binding side chain, FDA approved as Sogroya for adult and pediatric growth hormone deficiency and, since 2026, three non-GHD pediatric growth disorders.

Also referenced as: Somapacitan-beco, Sogroya, NNC0195-0092, NNC-0195-0092

Also appears in: Hormone

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What is Somapacitan?

Somapacitan is a long-acting derivative of human growth hormone, not a short peptide: its protein backbone is the full 191-amino-acid hGH sequence, expressed in Escherichia coli, with a single leucine-to-cysteine substitution at position 101 (L101C) to which a small (about 1.2 kDa) albumin-binding side chain is attached, for a total molecular weight of roughly 23.3 kDa. The side chain binds reversibly and non-covalently to circulating albumin, which slows clearance enough to support once-weekly injection in place of the daily somatropin regimen. Developed by Novo Nordisk under the code NNC0195-0092 and marketed as Sogroya (U.S. nonproprietary name somapacitan-beco), it was approved by the FDA on August 28, 2020 for adults with growth hormone deficiency, on April 28, 2023 for pediatric GHD, and on February 27, 2026 for three further pediatric growth disorders.

It is the first once-weekly growth hormone approved in the United States and a reference point for how the GH field has moved from daily peptide-hormone injections to engineered long-acting proteins. It has no research-market presence to speak of: a recombinant, site-specifically modified protein supplied only in proprietary prefilled pens is not something that circulates as lyophilized vials, and “weekly growth hormone” listings should not be assumed to contain it.

How it works

Somapacitan is a growth hormone receptor agonist with the same downstream biology as endogenous GH; the engineering is about residence time, not a new mechanism.

• Full GH receptor pharmacology — the molecule binds the dimeric GH receptor and activates the same intracellular signaling as native hGH, with effects mediated partly through hepatic IGF-1 and partly through direct receptor activation in peripheral tissues; in primary hepatocytes and hepatocellular models, signaling kinetics were only slightly less rapid and intense than for unmodified GH, and fluorescent-labeled somapacitan distributed to the hypertrophic zone of the proximal tibial epiphysis and activated GH receptor signaling in epiphyseal tissue of hypophysectomized rats (Petersen et al., International Journal of Molecular Sciences, 2020, 21(4):1181)
• Reversible albumin binding extends half-life — isothermal titration calorimetry identified one high-affinity (roughly 100–1,000 nM) somapacitan binding site in domain III of human serum albumin, overlapping the region shielded by the neonatal Fc receptor, plus a lower-affinity (roughly 1,000–10,000 nM) interaction that a crystal structure with an FcRn-optimized albumin variant placed in fatty-acid site 6 of domain II; because the interaction is non-covalent, free drug is in continuous equilibrium with the albumin-bound reservoir (Johansson et al., Biochemistry, 2020, 59(14):1410–1419). The approved label states that the drug is more than 99% protein-bound, with a half-life of about 2 to 3 days in adults with GHD and about 34 to 37 hours in children
• Species-consistent pharmacokinetics predicted the weekly profile — in rats, minipigs and cynomolgus monkeys the terminal half-life lengthened with body size (5–6 h, 10–12 h and 17–20 h respectively) with first-order absorption and no absorption-limited elimination, plasma IGF-1 stayed elevated for up to 10 days after a single dose, and in hypophysectomized rats once-weekly dosing produced a step-wise body-weight gain with a linear growth phase over the first 3–4 days of each weekly interval (Thygesen et al., Growth Hormone & IGF Research, 2017, 35:8–16)
• IGF-1 exposure is pulsed on a weekly cycle — in the first multiple-dose human study (34 GH-treated adults with GHD, four dose cohorts of 0.02–0.12 mg/kg once weekly for four weeks), exposure rose with dose and the 0.02 and 0.04 mg/kg doses produced IGF-1 levels similar to daily GH, with no immunogenicity signal; the label notes that IGF-1 peaks 2 to 4 days after each weekly dose in adults, which is why monitoring timing matters when the product is used clinically (Rasmussen et al., Journal of Clinical Endocrinology & Metabolism, 2016, 101(3):988–998)

Research status

Somapacitan has a completed registrational program in adults and children (the REAL series), multiple approvals, and ongoing long-term extensions and registries. All pivotal trials were active-comparator designs against daily somatropin (Norditropin); only the adult pivotal study had a placebo arm, and only for its first 34 weeks.

Adult GHD: REAL 1 (NCT02229851). A Phase 3 trial in 17 countries randomized 301 treatment-naïve adults with GHD 2:2:1 to once-weekly somapacitan (n = 120), daily somatropin (n = 119, open-label) or weekly placebo (n = 60, double-blind). The primary endpoint, change in truncal fat percentage at week 34, was −1.06% for somapacitan versus +0.47% for placebo (estimated difference −1.53%; 95% CI −2.68 to −0.38; P = 0.0090); visceral fat, lean body mass and IGF-1 SDS also improved versus placebo. In the 52-week open-label extension to week 86, improvements were maintained on both somapacitan and daily GH, with similar adverse-event and injection-site-reaction rates (Johannsson et al., Journal of Clinical Endocrinology & Metabolism, 2020, 105(4):e1358–e1376). The label states that no formal statistical comparison between somapacitan and daily somatropin was performed in adults, and the primary endpoint is a body-composition surrogate rather than a clinical outcome. Two further Phase 3 studies covered previously treated adults switching from daily GH: REAL 2 (NCT02382939), a 26-week multinational safety trial (n = 92), and REAL Japan (NCT03075644), a 52-week Japanese trial (n = 46 somapacitan, n = 16 daily GH) in which adverse-event rates, IGF-1 SDS and adipose-tissue changes were similar between arms (Otsuka et al., Clinical Endocrinology, 2020, 93(5):620–628). A pooled post hoc analysis of REAL 1, REAL 2 and REAL Japan found no adverse effect of weekly somapacitan on glucose metabolism over up to 86 weeks (Takahashi et al., Pituitary, 2023, 26(1):57–72).

Pediatric GHD: REAL 3 and REAL4. REAL 3 (NCT02616562) was a Phase 2 dose-finding study at 29 sites in 11 countries that randomized 59 treatment-naïve prepubertal children to somapacitan 0.04, 0.08 or 0.16 mg/kg/week or daily GH 0.034 mg/kg/day; the 0.16 mg/kg/week dose gave the closest match to daily GH at 26 and 52 weeks (Sävendahl et al., Journal of Clinical Endocrinology & Metabolism, 2020, 105(4):e1847–e1861), and 3-year follow-up showed sustained height-based outcomes (Sävendahl et al., Journal of Clinical Endocrinology & Metabolism, 2022, 107(5):1357–1367). REAL4 (NCT03811535), the Phase 3 pivotal trial, randomized 200 treatment-naïve prepubertal children at 86 sites in 20 countries 2:1 to somapacitan 0.16 mg/kg/week (n = 132) or daily GH 0.034 mg/kg/day (n = 68). Estimated annualized height velocity at week 52 was 11.2 versus 11.7 cm/year (treatment difference −0.5; 95% CI −1.1 to 0.2), confirming noninferiority, with similar IGF-1 SDS and injection-site-reaction rates of 5.3% versus 5.9% (Miller et al., Journal of Clinical Endocrinology & Metabolism, 2022, 107(12):3378–3388). Two-year results, including children switched from daily GH, and three-year results have since been published (Miller et al., Journal of Clinical Endocrinology & Metabolism, 2023, 108(12):3090–3099; Miller et al., European Journal of Endocrinology, 2025, 192(5):651–661). The trial completed in September 2025; final-height data are not yet available.

Non-GHD pediatric growth disorders: REAL8 (NCT05330325). An open-label Phase 3 basket study (412 participants, 52-week main phase plus 104-week extension, estimated completion October 2027) tested somapacitan 0.24 mg/kg/week against daily GH in four treatment-naïve prepubertal cohorts, each with height velocity at week 52 as its primary endpoint:

• Small for gestational age (142 children, randomized 2:1:1): 11.0 cm/year on somapacitan versus 9.4 cm/year on daily GH 0.035 mg/kg/day (ETD 1.6; 95% CI 0.91 to 2.23, superiority shown) and 11.1 cm/year on daily GH 0.067 mg/kg/day (ETD −0.1; 95% CI −0.75 to 0.60); noninferior to both (Linglart et al., European Journal of Endocrinology, 2026, 194(3):311–325)
• Noonan syndrome (77 children): 10.4 versus 9.2 cm/year (ETD 1.2; 95% CI 0.32 to 2.03; P < 0.01), noninferior and superior to daily GH 0.050 mg/kg/day (Jorge et al., European Journal of Endocrinology, 2026, 194(3):393–403)
• Idiopathic short stature (88 children in 20 countries): observed mean 10.2 versus 10.6 cm/year (ETD −0.3; 95% CI −1.00 to 0.42), noninferior to daily GH 0.050 mg/kg/day (Abuzzahab et al., European Journal of Endocrinology, 2026, 194(2):242–253)
• Turner syndrome (105 girls aged 2.5 to 10, 49 clinics in 18 countries): observed means 9.0 versus 9.5 cm/year on daily GH 0.050 mg/kg/day; estimated treatment difference −0.8 (95% CI −1.57 to −0.11). Noninferiority was confirmed against the prespecified margin, but the confidence interval excludes zero, so daily GH produced statistically greater 52-week height velocity in this cohort; IGF-1 SDS was +1.71 versus +1.95 at week 52 and no participant stopped treatment for adverse events (Mauras et al., Journal of Clinical Endocrinology & Metabolism, 2026, online ahead of print, August 2026)

A related Phase 2 dose-finding study in SGA children (NCT03878446) remains active, and a separate Phase 3 safety study, REAL 9 (NCT05723835), follows children across the same four indications.

Regulatory record. The U.S. BLA (761156) was approved on August 28, 2020 for adult GHD, supplemented on April 28, 2023 for pediatric GHD in children aged 2.5 and older, and supplemented again on February 27, 2026 with three efficacy approvals covering SGA without catch-up growth by age 2, growth failure associated with Noonan syndrome, and idiopathic short stature, all from age 2.5. A labeling supplement approved in July 2025 added slipped capital femoral epiphysis to the warnings. Turner syndrome is not an approved U.S. indication: it does not appear in the current label (revised 2/2026) or in the FDA’s published approval history for the BLA, and the 52-week REAL8 Turner data were only published in August 2026. In the European Union, marketing authorization was granted on March 31, 2021 for adults and later extended to children aged 3 and older and adolescents with GHD. The product is also approved in Japan and a number of other markets. No complete response letter, withdrawal or discontinued indication is on record for the molecule.

Post-approval evidence. Long-term observational follow-up of treated children (NCT06709040) and adults (NCT05718570) is enrolling by invitation, and several 2024–2026 systematic reviews and network meta-analyses comparing long-acting with daily GH consistently find comparable 52-week height velocity with no new safety signal, while noting that adult-height and multi-year safety data remain immature for the whole long-acting class.

Common dosage forms

• Prefilled multidose pens (the only format) — single-patient-use pens containing 5 mg, 10 mg or 15 mg of somapacitan-beco in 1.5 mL (3.3, 6.7 and 10 mg/mL), color-coded teal, yellow and red, supplied as a clear solution requiring no reconstitution. The EU presentations follow the same 5/10/15 mg scheme.
• Storage — pens are refrigerated at 2–8 °C and must not be frozen.
• Labeled in milligrams, not IU — unlike many somatropin products that are still described in international units, somapacitan is expressed in mg and mg/kg/week throughout its labeling, which is a format detail worth knowing when reading its literature alongside daily-GH studies.
• Not available as vials or lyophilized powder — there is no bulk, vial or powder presentation in any market, and no research-grade supply chain for the molecule exists.

Key considerations

• Approval is real and broad for a GH product, but every indication is a diagnosed growth or deficiency disorder. The FDA Approved status reflects Sogroya’s U.S. approvals for adult GHD, pediatric GHD and (since February 27, 2026) SGA, Noonan syndrome and idiopathic short stature. Turner syndrome has published Phase 3 data that met noninferiority but is not on the U.S. label as of November 2026. The label is prescription-only and carries contraindications for acute critical illness, active malignancy, closed epiphyses in children, active proliferative or severe non-proliferative diabetic retinopathy, and severely obese or respiratory-compromised children with Prader-Willi syndrome; nothing in the approval record extends to body-composition, anti-aging or performance use in people without GHD.
• It is a protein, not a peptide, and not somatropin. Somapacitan is the full 191-residue hGH protein with an engineered cysteine carrying an albumin-binding side chain; the U.S. suffix “-beco” is a nonproprietary-name distinguisher, not a different molecule. It shares the GH receptor with somatropin but has a different half-life, dosing unit and weekly IGF-1 profile, so milligram-for-milligram or IU-based comparisons with daily GH are not meaningful. It should also not be confused with other long-acting GH technologies such as the PEGylated prodrug lonapegsomatropin or the C-terminal-peptide fusion somatrogon, which use different mechanisms of half-life extension.
• The pivotal evidence is noninferiority against daily GH, not placebo-controlled outcome data. Apart from the 34-week placebo arm in REAL 1, every efficacy trial was an open-label comparison with daily somatropin, powered on 52-week height velocity in children or truncal fat in adults. These designs establish equivalence of a surrogate, not long-term benefit: adult height, fracture and cardiometabolic outcomes, and safety beyond three to four years are still being collected in extensions and registries, and the adult trial performed no formal statistical test of somapacitan against daily GH.
• The safety profile is the GH class profile, plus a documented immunogenicity rate. Labeled warnings mirror somatropin (neoplasm risk, glucose intolerance, intracranial hypertension, fluid retention, hypoadrenalism, hypothyroidism, slipped capital femoral epiphysis, scoliosis progression, pancreatitis). Anti-drug antibodies developed in 12.1% of children with GHD, 14.5% in SGA, 4.1% in Noonan syndrome and 11.9% in ISS during the 52-week main periods, with no neutralizing antibodies and no detected effect on exposure or growth; none were detected in adults. Lipohypertrophy and lipoatrophy at injection sites are labeled, and a reversible lipoatrophy case in an adult has been published (Rakusa et al., Pituitary, 2024, 27(5):737–739).
• Absence from the research market is informative. A site-specifically acylated recombinant protein in a proprietary pen cannot be reproduced by the peptide-synthesis supply chain, and no vial or powder form of somapacitan exists. Material marketed as “weekly HGH” or under a somapacitan name outside pharmacy channels has no plausible route to being the approved molecule, and the published pharmacology above applies only to the approved product in its labeled indications.