# CJC-1295 Research: Mechanism, DAC vs no-DAC, and Reported Effects in Published Trials

> What the published research on CJC-1295 shows: GHRH receptor agonism, Gαs/cAMP signaling, pulsatile GH amplification, and the difference between CJC-1295 DAC and CJC-1295 no DAC.

_PART II — THE MECHANISM_

**CJC-1295 Research: The GHRH Receptor, the Albumin Linker, and the Pulsatile Signal**

CJC-1295 binds a class-B G-protein-coupled receptor on pituitary somatotrophs, amplifies the body's own pulsatile growth hormone release, and — in its DAC variant — keeps the signal running for days. The molecular detail and the published results.

## CJC-1295 Mechanism of Action

CJC-1295 binds the growth hormone-releasing hormone receptor — GHRHR, encoded on chromosome 7p14.3 — a class B G-protein-coupled receptor on pituitary somatotrophs [20]. Agonist binding activates the Gαs subunit, raises intracellular cAMP through adenylyl cyclase, activates protein kinase A, phosphorylates CREB, induces the somatotroph-specific transcription factor Pit-1, and triggers voltage-gated Ca2+ influx that drives exocytosis of preformed GH secretory granules [05]. The receptor's cryo-EM structure was published in 2020 [05]; a 2025 review of GHRHR signaling frames it as the single shared molecular target across every clinically studied GHRH analog — sermorelin, tesamorelin, CJC-1295, modified GRF 1-29 [20].

The pulse architecture matters. Endogenous GH is released in discrete bursts, chiefly during slow-wave sleep, not continuously. GHRH analogs amplify the amplitude of those bursts; exogenous recombinant GH overrides the rhythm with sustained apulsatile elevation. This is the mechanistic argument for studying GHRH analogs at all: they work with the body's clock rather than overriding it.

### GHRH receptor agonism and pulsatile GH amplification

CJC-1295 binds pituitary GHRHR and amplifies endogenous pulsatile GH release from somatotrophs rather than supplying exogenous GH itself. The DAC variant extends this amplification across days; the non-DAC variant produces a single GH pulse lasting roughly 60-90 minutes versus 15-20 minutes for native sermorelin [13].

## CJC-1295 DAC vs CJC-1295 (Modified GRF 1-29)

CJC-1295 DAC and the variant sold as CJC-1295 no DAC are two distinct peptides with the same 29-residue backbone. The difference is one linker.

The DAC linker is a maleimidopropionyl group attached to a 30th C-terminal lysine. In plasma, the maleimide reacts selectively with the free thiol of Cys34 on human serum albumin to form a stable covalent thioether [02][12]. The conjugated peptide rides circulating albumin, whose half-life is near 19 days, and is shielded from renal and proteolytic clearance. In Teichman's healthy-adult trials, plasma CJC-1295 was estimated at a 5.8- to 8.1-day half-life and produced pharmacologically relevant GH and IGF-1 elevation for six to eleven days from a single subcutaneous injection [01].

In ConjuChem's preclinical rat assay, albumin-bound CJC-1295 immunoreactivity appeared in circulation within 15 minutes of injection and persisted beyond 72 hours [03][14]. The same paper identified CJC-1295 as the most potent of three maleimido hGRF(1-29) bioconjugates synthesized, producing a four-fold increase in GH area-under-curve over two hours compared with unmodified hGRF(1-29) in cultured rat anterior pituitary cells [03].

### CJC-1295 without DAC (Modified GRF 1-29)

CJC-1295 no DAC is the same peptide minus the albumin linker. Its half-life in plasma is approximately 30 minutes — extended from native sermorelin's sub-10-minute half-life by the DPP-IV-resistant substitutions, but no longer than that [04][13]. Research protocols administer it as multiple daily subcutaneous injections, typically 100-500 mcg per injection, one to three times daily [13]. The GH pulse it generates is roughly 60-90 minutes long, a more physiologic 'pulse-like' release pattern than the multi-day signal the DAC variant produces.

### Modified GRF 1-29 (Tetra-Substituted GHRH 1-29)

Modified GRF 1-29 is the scientific name for tetrasubstituted GHRH(1-29) — the same peptide as CJC-1295 no DAC, with the same four substitutions (D-Ala2, Gln8, Ala15, Leu27) [02]. The 'modified GRF' nomenclature is the one used in mechanistic and pharmacokinetic literature; 'CJC-1295 no DAC' is the lay-and-research-chemical label. Treating the two terms as synonyms is correct; treating modified GRF 1-29 as equivalent to the DAC variant is not.

## Researched Effects of CJC-1295

Two pharmacodynamic endpoints anchor the literature. First, growth hormone: single ascending subcutaneous doses up to 250 mcg/kg in healthy adults produced two- to ten-fold elevations in mean plasma GH sustained for six days or more [01]. Second, IGF-1: those same doses raised mean serum IGF-1 1.5- to 3-fold for nine to eleven days [01]. Multiple-dose Phase 1 trials, with weekly or biweekly subcutaneous administration, maintained mean IGF-1 above baseline for up to 28 days [01].

In the cultured rat anterior pituitary assay, CJC-1295 produced a four-fold increase in GH area-under-curve over two hours compared to unmodified hGRF(1-29) [03]. Pulsatile release was preserved — the analog amplified existing pulse amplitude rather than collapsing the pulse architecture into continuous elevation [01].

No published Phase 2 efficacy data has appeared in peer-reviewed form. ConjuChem registered NCT00267527 for HIV-associated visceral obesity, enrolling roughly 192 adults on weekly escalating doses of 60-240 mcg/kg [18]. The program was halted before completion, and the efficacy endpoints — body composition, visceral fat reduction, IGF-1 area-under-curve — were never published.

## CJC-1295 Results in Published Trials

Two peer-reviewed primary papers carry most of the load. Jetté 2005 in Endocrinology is the preclinical pharmacology paper: receptor binding, in vitro pituitary cell secretion, in vivo rat plasma persistence, and identification of CJC-1295 as the most potent of three maleimido bioconjugates [03]. Teichman 2006 in JCEM is the human Phase 1 paper: two ascending-dose trials in healthy adults, the 5.8- to 8.1-day half-life, the two- to ten-fold GH elevation, the 1.5- to 3-fold IGF-1 elevation, the 28-day multi-dose IGF-1 trajectory [01].

Analytical literature has continued. Henninge 2010 confirmed CJC-1295's identity in a seized pharmaceutical preparation by LC-HRMS/MS, establishing reference data for anti-doping detection [08]. Timms 2019 developed an immunoaffinity-capture LC-MS/MS confirmation for albumin-bound CJC-1295 in equine plasma [09]. A 2021 review surveyed antibody-free nano-LC-HRMS/MS methods capable of detecting GHRH synthetic analogs at sub-picogram-per-milliliter sensitivity in urine [19]. The compound is a Prohibited Substance under Section S2 of the World Anti-Doping Agency Code and is detected by validated assays in WADA-accredited laboratories [15].

## Time course of reported effects in published studies

Pulsatile GH amplitude rose within 24 to 48 hours of a single subcutaneous dose in healthy adults and remained elevated for six to nine days; serum IGF-1 rose more slowly and stayed elevated for nine to eleven [01]. In the 28- to 49-day multi-dose Phase 1 trials, weekly or biweekly subcutaneous administration of 30-60 mcg/kg maintained mean IGF-1 above baseline across the full trial window [01]. No published trial has reported a body-composition endpoint in the public literature.

## CJC-1295 vs Ipamorelin: Class and Mechanism

CJC-1295 is a GHRH analog. Ipamorelin is a growth hormone secretagogue receptor agonist — it binds GHS-R1a, the ghrelin receptor, not the GHRH receptor [10]. The two molecules act on two different receptors that signal through two different intracellular cascades and converge on the same target cell. GHRHR signals through Gαs / cAMP / PKA; GHS-R1a signals through Gq / PLC / IP3 / Ca2+ [05][10]. Co-administration of a GHRH receptor agonist with a GHS-R agonist produced GH responses substantially greater than either alone in the Bowers laboratory's clinical pharmacodynamic studies, because the two pathways converge synergistically on somatotroph GH exocytosis rather than competing [10].

This is a mechanistic observation about receptor pharmacology in the published record. It is not an endorsement of any stacking protocol. The portfolio is editorial.

## Endpoints in published trials

Across the Teichman 2006 record the measured endpoints were: pulsatile GH amplitude and area-under-curve, mean serum GH across the dosing interval, serum IGF-1, serum IGFBP-3, the pharmacokinetic parameters of the peptide itself (peak plasma concentration, time to peak, half-life), and adverse-event tracking [01]. The Phase 2 HIV lipodystrophy program (NCT00267527) added visceral adipose tissue by imaging as the primary efficacy endpoint, but that data was never published [18].

## Research applications studied to date

CJC-1295 has been studied as a long-acting GH secretagogue in healthy adults (Teichman 2006 Phase 1) and in HIV-associated visceral obesity (the discontinued Phase 2 NCT00267527) [01][18]. Preclinical work has examined GHRH receptor binding, pituitary cell secretion, rat plasma pharmacokinetics, and the albumin-bioconjugation kinetics that underwrite the weekly-dosing model [03][14]. The compound has also been studied in animal models of muscle, bone, and fat metabolism as a tool for amplifying the GH/IGF-1 axis in research contexts. No published study has demonstrated meaningful change in serum testosterone — CJC-1295 acts on the GHRH/GH/IGF-1 axis, not the hypothalamic-pituitary-gonadal axis [01].

## References

[01] Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab. 2006;91(3):799-805. — doi:10.1210/jc.2005-1536 · PMID 16352683 · https://pubmed.ncbi.nlm.nih.gov/16352683/
[02] Jetté L, Léger R, Thibaudeau K, Benquet C, Robitaille M, Pellerin I, Paradis V, van Wyk P, Pham K, Bridon DP. Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog. Endocrinology. 2005;146(7):3052-3058. — doi:10.1210/en.2004-1286 · PMID 15817669 · https://pubmed.ncbi.nlm.nih.gov/15817669/
[03] Jetté L, Léger R, Thibaudeau K, et al. Identification of CJC-1295 as a long-lasting GRF analog: rat anterior pituitary cell pharmacology and in vivo plasma persistence (preclinical findings). Endocrinology. 2005;146(7):3052-3058. — doi:10.1210/en.2004-1286 · PMID 15817669 · https://pubmed.ncbi.nlm.nih.gov/15817669/
[04] Jetté L, Léger R, et al. DPP-IV resistance and extended in vitro plasma stability of tetrasubstituted GHRH(1-29) (preclinical PK data, same source as ref 2/3). Endocrinology. 2005;146(7):3052-3058. — doi:10.1210/en.2004-1286 · PMID 15817669 · https://pubmed.ncbi.nlm.nih.gov/15817669/
[05] Zhou F, Zhang H, Cong Z, Zhao L-H, Zhou Q, Mao C, Cheng X, Xu HE, et al. Structural basis for activation of the growth hormone-releasing hormone receptor. Nat Commun. 2020;11(1):5205. — doi:10.1038/s41467-020-18945-0 · PMID 33060564 · https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7567103/
[08] Henninge J, Pepaj M, Hullstein I, Hemmersbach P. Identification of CJC-1295, a growth-hormone-releasing peptide, in an unknown pharmaceutical preparation. Drug Test Anal. 2010;2(11-12):647-650. — doi:10.1002/dta.233 · PMID 21204297 · https://pubmed.ncbi.nlm.nih.gov/21204297/
[09] Timms M, Hall N, Levina V, Vine J, Steel R. A method for confirming CJC-1295 abuse in equine plasma samples by LC-MS/MS. Drug Test Anal. 2019;11(7):1085-1093. — doi:10.1002/dta.2599 · https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/dta.2599
[10] Veldhuis JD, Bowers CY. Determinants of GH-releasing hormone and GH-releasing peptide synergy in men. Am J Physiol Endocrinol Metab. 2009;296(5):E1085-E1092. — doi:10.1152/ajpendo.91001.2008 · PMID 19240251 · https://pubmed.ncbi.nlm.nih.gov/19240251/
[12] Bridon DP, ConjuChem Inc. Drug Affinity Complex (DAC) technology overview. 2005. — https://www.conjuchem.com/technology/dac.html
[13] Modified GRF (1-29) pharmacology overview. Review article citing original GHRH analog pharmacology literature. 2024. — https://en.wikipedia.org/wiki/Modified_GRF_(1-29)
[14] Jetté L, Léger R, et al. Albumin-bound CJC-1295 immunoreactivity in rat plasma — appears within 15 minutes, persists beyond 72 hours (preclinical PK data, same source as ref 2/3). Endocrinology. 2005;146(7):3052-3058. — doi:10.1210/en.2004-1286 · PMID 15817669 · https://pubmed.ncbi.nlm.nih.gov/15817669/
[15] World Anti-Doping Agency. The 2025 Prohibited List. WADA Code Prohibited List, annual publication. 2025. — https://www.wada-ama.org/en/prohibited-list
[18] ConjuChem Biotechnologies (sponsor). A Study to Evaluate CJC 1295 in HIV Patients With Visceral Obesity. ClinicalTrials.gov identifier NCT00267527. 2007. — https://clinicaltrials.gov/study/NCT00267527
[19] Memdouh S, Gavrilović I, Ng K, Cowan D, Abbate V. Advances in the detection of growth hormone releasing hormone synthetic analogs. Drug Test Anal. 2021;13(11-12):1871-1887. — doi:10.1002/dta.3183 · PMID 34665524 · https://pubmed.ncbi.nlm.nih.gov/34665524/
[20] U.S. Food and Drug Administration. Pharmacy Compounding Advisory Committee (PCAC) Meeting; Bulk Drug Substances Nominated for Inclusion on the 503A Bulk Drug Substances List. December 2024 briefing documents. — https://www.fda.gov/media/183819/download

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An unrolled scroll of the peer-reviewed CJC-1295 literature, read in sumi-ink and a single vermillion seal — not a clinic, not a pharmacy, not a prescription.