CJC-1295 Research

CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH), engineered for an extended plasma half-life through covalent albumin binding via the Drug Affinity Complex (DAC) mechanism. Preclinical and early-phase research has investigated sustained changes in growth hormone and IGF-1 signaling compared to native GHRH. Research is ongoing and all findings require further clinical validation.

This article will discuss the peptide structure of CJC-1295 and the drug-affinity complex model of which it is part. It also covers the physiological effects the peptide exerts upon binding to GHRH receptors in the somatotropic axis. The information presented here is based on the preclinical literature and does not represent expected results in human subjects.

CJC-1295 is a modified GHRH analog

Natural GHRH is a hypothalamic hormone composed of 44 amino acids. Of those, the first 29 amino residues, GRF(1-29), maintain their physiological effects on the GHRH receptor. CJC-1295 is constructed on this 1-29 backbone, and according to Jette et al., the synthetic peptide carries four amino acid substitutions [D-Ala2, Gln8, Ala15, Leu27].^[1]

The modification at position 2 confers resistance to dipeptidyl peptidase-4, the enzyme that inactivates natural GRF(1-29) in blood plasma by cleaving between residues 2 and 3. The other three substitutions address different liabilities rather than proteolysis. Gln8 replaces an asparagine prone to deamidation in aqueous solution, and Leu27 replaces the peptide's only methionine, which is prone to oxidation. Ala15 replaces glycine to increase GHRH-receptor binding affinity rather than to improve stability.

This core structure is also known as modified GRF(1-29), and on its own it is a more stable analog of GHRH. It is still short-acting, though, relative to the form that carries the Drug Affinity Complex (DAC).

How DAC extends the activity of CJC-1295

What distinguishes CJC-1295 is its ability to form a DAC. Specifically, in the DAC form, the GRF(1-29)-modified analog contains a reactive chemical group, a maleimido-based linker. That linker covalently binds to circulating serum albumin upon entering the bloodstream, by reacting with a cysteine residue on albumin.

Albumin is highly abundant and relatively stable, so linking the peptide to albumin serves a dual purpose. It protects the analog from rapid elimination, and it extends the duration of action of this otherwise short half-life fragment of GHRH to days.

This albumin bioconjugate was identified as CJC-1295 by Jette et al., who showed in rats that it still activates the GHRH (GRF) receptor on the anterior pituitary.^[1] That confirmed that binding to albumin does not stop it from acting at the receptor.

The two forms are therefore not interchangeable. Only the DAC-bearing conjugate binds albumin and acts over days, and that conjugate is the material identified as CJC-1295 by Jetté et al. The modified GRF(1-29) core sold as "CJC-1295 (No DAC)" lacks the maleimido linker, remains short-acting, and does not acquire the extended duration of action described above. The pharmacokinetic and duration-of-action findings discussed below were all generated with the DAC form.

CJC-1295 and GHRH receptor signaling in the somatotropic axis

The mechanism of action of CJC-1295 is similar to that of GHRH itself. The receptor for GHRH is a class B G protein-coupled receptor found in the somatotroph cells in the anterior pituitary gland.

As described by Mayo, agonist binding couples to the stimulatory G protein (Gs), activates adenylyl cyclase, raises intracellular cyclic AMP, and drives both the synthesis and the pulsatile release of growth hormone.^[2]

GH then stimulates hepatic production of insulin-like growth factor 1 (IGF-1), the main circulating mediator of GH's effects, which feeds back to restrain the axis. By engaging this receptor with a long half-life, CJC-1295 acts as a growth hormone secretagogue of the GHRH class, distinct from the ghrelin-mimetic secretagogues that work through a separate receptor.

What the preclinical research shows

Preclinical research on CJC-1295 established both the receptor action and the molecule's longevity. The foundational study in rats, by Jette et al., showed that the albumin-conjugated analog activated the GRF receptor on the anterior pituitary.^[1] The same study showed that the analog produced roughly a four-fold increase in growth hormone area under the curve over a two-hour window compared with hGRF(1-29). The authors also reported that the conjugate itself remained detectable in plasma beyond 72 hours. That study measured GH secretion and pharmacokinetics. It did not measure IGF-1.

Alba and colleagues then tested the analog in a GHRH-knockout mouse, an animal that cannot make its own GHRH and is therefore growth-retarded.^[3] Over five weeks, once-daily administration normalized body weight and length in these animals and increased pituitary GH mRNA. That indicates the analog can substitute functionally for the absent native hormone.

The same dose given every 48 or 72 hours improved growth over placebo, but it did not fully normalize growth. The authors concluded the compound is less effective at those longer intervals. These are animal findings in controlled models, not an outcome to be expected in people.

Human research on CJC-1295

Human research on CJC-1295 is minimal, and it should be read as entirely separate from the animal work. Human pharmacology has been characterized in a small number of early-phase studies in healthy volunteers, which were designed to measure how the analog behaves in the body.^[4][5] They were not designed to test a clinical endpoint.

Beyond these, ConjuChem ran a multicenter, randomized, placebo-controlled, double-blind Phase 2 trial of CJC-1295 (DAC) over 12 weeks in HIV-infected patients with HIV-associated visceral obesity (ClinicalTrials.gov NCT00267527). That trial is listed as terminated, and it was halted in July 2006 after a participant died. The relationship of the death to the study drug was not established. Clinical development of CJC-1295 was not resumed, however, and no sponsor has taken it into a registered trial since.

There are no large or long-term controlled trials, independent replication is limited, and there is no approved indication. As of 2026, CJC-1295 is not an approved drug. Readers should treat any extrapolation from this early pharmacology to a real-world human outcome as unsupported.

How CJC-1295 differs from sermorelin

The comparison between CJC-1295 and sermorelin is largely structural. Sermorelin is GRF(1-29), the unmodified 29-amino-acid fragment, and it acts at the same GHRH receptor but is cleared quickly because it lacks the stabilizing changes.

CJC-1295 is the same fragment, reinforced. The modified GRF(1-29) substitutions modestly extend its half-life, and the DAC version extends it dramatically through albumin binding. Both are GHRH-class growth hormone secretagogues and share a mechanism. What differs is durability, which is precisely the property CJC-1295 research has set out to characterize.

Current limitations and open questions

There are several considerations that shape any interpretation of CJC-1295 research. There is no approved therapeutic indication, and the compound is not characterized for human use. The long-term consequences of sustained GHRH receptor stimulation are not well characterized, even in preclinical models. Those consequences include effects on the feedback architecture of the axis and on IGF-1 over time.

Much of the work to date is preclinical, independent replication is limited, and the purity and identity of material vary across sources. That matters for any laboratory study using research-grade CJC-1295. Overall, its mechanism is well grounded and the pharmacokinetic profile is distinctive, but the evidence base remains limited.

Conclusion

CJC-1295 is a modified GHRH analog whose defining trait is engineered longevity. It is a stabilized GRF(1-29) core, optionally tethered to albumin via the DAC, acting at the GHRH receptor. Its plasma residence time is measured in days rather than minutes in preclinical models. The preclinical work is coherent and the pharmacokinetic rationale is clear, but the overall evidence base remains limited, with no approved indication.

They do not describe what any individual should expect. For the full range of research peptides available for laboratory use, see the Pure Peptides catalog.

References

1. 1

   Jetté L, Léger R, Thibaudeau K, Benquet C, Robitaille M, Pellerin I, et al. 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 Jul;146(7):3052-8. doi:10.1210/en.2004-1286. PMID 15817669.
2. 2

   Mayo KE, Miller T, DeAlmeida V, Godfrey P, Zheng J, Cunha S. Regulation of the pituitary somatotroph cell by GHRH and its receptor. Recent Prog Horm Res. 2000;55:237-266. PMID 11036940.
3. 3

   Alba M, Fintini D, Sagazio A, Lawrence B, Castaigne JP, Frohman LA, Salvatori R. Once-daily administration of CJC-1295, a long-acting growth hormone-releasing hormone (GHRH) analog, normalizes growth in the GHRH knockout mouse. Am J Physiol Endocrinol Metab. 2006 Dec;291(6):E1290-4. doi:10.1152/ajpendo.00201.2006. PMID 16822960.
4. 4

   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 Mar;91(3):799-805. doi:10.1210/jc.2005-1536. PMID 16352683.
5. 5

   Ionescu M, Frohman LA. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. J Clin Endocrinol Metab. 2006 Dec;91(12):4792-7. doi:10.1210/jc.2006-1702. PMID 17018654.