CJC-1295 Without DAC: Published Research

Introduction

CJC-1295 without DAC (Modified GRF 1-29) is a tetrasubstituted analog of the 29-amino acid N-terminal fragment of human growth hormone-releasing hormone (GHRH). The peer-reviewed research base for this specific compound draws on studies of structurally related compounds — including the albumin-conjugated variant CJC-1295 with DAC, the unmodified predecessor sermorelin, and the tetrasubstituted scaffold characterized in preclinical laboratory settings. This article summarizes the published research most directly pertinent to understanding the scientific context of CJC-1295 without DAC, noting methodology and scope for each body of evidence.

Methodology Types in the Research Literature

Research relevant to CJC-1295 without DAC encompasses three methodological categories. First, in vitro biochemical and cell-based studies assessed proteolytic stability, receptor binding, and GH secretory responses in cultured pituitary cell preparations. Second, preclinical in vivo studies using rodent models — including genetically modified mice lacking endogenous GHRH signaling — characterized growth-related outcomes under controlled pharmacological GHRH agonism. Third, a small number of randomized, placebo-controlled human clinical trials examined GH and IGF-1 secretory responses to injected GHRH analogs (principally CJC-1295 with DAC) under closely monitored conditions.

The published human clinical data examine CJC-1295 with DAC rather than the without-DAC variant as an isolated investigational agent. Findings attributed to the tetrasubstituted GRF(1-29) scaffold in preclinical contexts involve the same molecular core, with the DAC moiety contributing to pharmacokinetic differences in some experimental designs. Readers should weigh this distinction when interpreting evidence.

Summary of Key Studies

Preclinical characterization: Jetté et al. (2005)

The foundational preclinical publication characterizing the CJC-1295 compound series was published by Jetté and colleagues in Endocrinology in 2005 [1]. This study synthesized a series of maleimidopropionyl derivatives of hGRF(1-29) incorporating the four amino acid substitutions (D-Ala², Gln⁸, Ala¹⁵, Nle²⁷) that define the CJC-1295 scaffold. In vitro experiments reported enhanced stability of these tetrasubstituted analogs against DPP-4 cleavage in bovine plasma compared with native hGRF(1-29). A particularly significant finding for understanding CJC-1295 without DAC: the non-bioconjugated (DAC-free) forms of the tetrasubstituted scaffold retained GHRH-R agonist activity in the rat anterior pituitary cell GH secretion assay. This in vitro result supports the conclusion that the tetrasubstituted backbone itself — the CJC-1295 without DAC chemical structure — is biologically active at the GHRH receptor independent of any albumin-binding contribution. The study was conducted using rat pituitary cells and human serum albumin conjugates; the findings do not establish human pharmacokinetics or pharmacodynamics.

Enzymatic degradation pathway: Frohman et al. (1989)

Frohman and colleagues characterized the plasma enzymatic degradation pathways for native human GHRH in a 1989 Journal of Clinical Investigation study [2]. Using radiolabeled peptide substrates and specific enzymatic inhibitors, the authors identified DPP-4 as the dominant protease responsible for N-terminal cleavage of GHRH, generating the biologically inactive GRF(3-29) fragment, with trypsin-like enzyme activity identified as a secondary mechanism. These mechanistic findings established the scientific rationale for position-2 D-Ala substitution as a DPP-4 resistance strategy — and directly informed the design of the tetrasubstituted scaffold that defines CJC-1295 without DAC.

Human pharmacokinetic and pharmacodynamic study: Teichman et al. (2006)

A landmark human study on the CJC-1295 compound class was published by Teichman and colleagues in the Journal of Clinical Endocrinology & Metabolism in 2006 [3]. This study examined CJC-1295 with DAC in two randomized, placebo-controlled, double-blind, ascending-dose trials conducted in healthy adults aged 21 to 61 years. Following single subcutaneous administration, investigators reported dose-dependent elevations in mean plasma GH concentrations — described as two- to ten-fold above baseline — sustained for six or more days, and mean plasma IGF-1 concentrations reported at 1.5- to three-fold above baseline lasting nine to eleven days. The authors characterized the compound as safe and relatively well-tolerated in this healthy adult population at the dose ranges studied.

The extended duration of GH and IGF-1 elevation observed in this trial is attributable to the covalent albumin-binding DAC moiety and is not representative of the pharmacodynamic profile expected from CJC-1295 without DAC. This trial is significant for the compound class, however, in that it provided the first human pharmacodynamic evidence for the tetrasubstituted GRF(1-29) scaffold's GH secretagogue activity in a controlled setting.

Pulsatile GH secretion under GHRH agonism: Ionescu and Frohman (2006)

Ionescu and Frohman published a 2006 study in the Journal of Clinical Endocrinology & Metabolism examining whether pulsatile GH secretion was preserved during sustained pharmacological GHRH-R stimulation by CJC-1295 with DAC in healthy men [4]. The study involved frequent GH sampling over twelve hours and reported that discrete GH pulses persisted during the period of elevated GHRH agonist exposure, with changes in pulse amplitude rather than replacement of pulsatile architecture with tonic GH release. The authors attributed maintained pulsatile secretion to intact somatostatinergic counter-regulation — a mechanistically significant finding that informs understanding of the broader GHRH-R agonist pharmacology class.

This finding has been cited in discussions of how shorter-acting GHRH analogs such as CJC-1295 without DAC may relate to physiological GH pulse generation, given that the without-DAC compound's shorter pharmacodynamic duration more directly approximates a discrete pulsatile stimulus.

Preclinical growth restoration in GHRH knockout model: Alba et al. (2006)

Alba and colleagues (2006), in a study published in the American Journal of Physiology — Endocrinology and Metabolism, examined the effects of CJC-1295 administration in GHRH knockout (GHRHKO) mice — animals that lack endogenous hypothalamic GHRH production and exhibit growth retardation [5]. Mice administered once-daily CJC-1295 for five weeks exhibited body weight and linear length measurements within the normal range of wild-type controls, whereas less-frequent administration showed progressively less complete growth normalization. The authors interpreted these results as evidence that the frequency of GHRH-R stimulation was an important determinant of outcomes in this model, and that once-daily administration was sufficient to sustain near-normal somatotroph responsiveness. These preclinical findings are cited in the research literature as evidence of the biological relevance of GHRH-R agonism in models of GHRH deficiency.

Sermorelin pharmacology review: Prakash and Goa (1999)

Prakash and Goa published a comprehensive review of sermorelin — the unmodified hGRF(1-29)-NH2 and structural predecessor to CJC-1295 without DAC — in BioDrugs in 1999 [6]. The review summarized sermorelin's pharmacology, pharmacokinetics, and clinical experience in pediatric GH deficiency, documenting a plasma half-life of eleven to twelve minutes following subcutaneous administration. This established half-life of the unmodified scaffold provides the benchmark against which the metabolic stabilization achieved by CJC-1295 without DAC's four-position substitutions can be understood — a half-life extension rooted in the DPP-4 resistance conferred by the D-Ala² substitution.

GH secretagogue class review: Ishida et al. (2020)

Ishida and colleagues published a systematic review of growth hormone secretagogue history, mechanism of action, and clinical development in JCSM Rapid Communications in 2020 [7]. The review classified GHRH-receptor agonists as a distinct category from GHS-R agonists and reviewed the pharmacological basis for their GH secretagogue activity. The review confirmed that GHRH-receptor agonists act through the pituitary cAMP-PKA signaling cascade to stimulate GH synthesis and secretion, distinguishing this mechanism from the intracellular calcium-mediated mechanism engaged by ghrelin mimetics.

Active Research Frontier

The published research base for CJC-1295 without DAC as a distinct compound identifies several areas where dedicated investigation would advance scientific understanding. Human pharmacokinetic characterization of CJC-1295 without DAC's specific plasma half-life, bioavailability, and pharmacodynamic GH secretory profile — currently inferred from the known DPP-4 resistance conferred by D-Ala² substitution and the absence of albumin binding — represents a meaningful research opportunity that would allow direct comparison with sermorelin and the DAC-bearing variant.

A head-to-head comparative study directly comparing CJC-1295 without DAC versus CJC-1295 with DAC or sermorelin under equivalent experimental conditions would precisely quantify the incremental contribution of each structural element to the compound's pharmacological profile — a study design that the existing literature has not yet provided.

The interaction of CJC-1295 without DAC with co-administered GHS-R agonists (such as GHRP-2, GHRP-6, or ipamorelin) represents an additional research frontier: the combinatorial pharmacology of dual-pathway GH secretagogue stimulation has a substantial mechanistic rationale documented in the GHRH-R pharmacology literature, and controlled preclinical characterization of this interaction would extend the current evidence base. These open questions define the active boundary of CJC-1295 without DAC research rather than fundamental limitations of the compound's scientific foundation. Research-grade CJC-1295 without DAC from SpartaLabs is independently tested and available for research applications.

References

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;146(7):3052-3058. PMID: 15817669. DOI: 10.1210/en.2004-1286

2. Frohman LA, Downs TR, Heimer EP, Felix AM. Dipeptidylpeptidase IV and trypsin-like enzymatic degradation of human growth hormone-releasing hormone in plasma. J Clin Invest. 1989;83(5):1533-1540. PMID: 2651468. DOI: 10.1172/JCI114049. PMC: PMC303858

3. 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. PMID: 16352683. DOI: 10.1210/jc.2005-1536

4. 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;91(12):4792-4797. PMID: 17018654. DOI: 10.1210/jc.2006-1702

5. Alba M, Fintini D, Sagazio A, Lawrence B, Castaigne JP, Frohman LA, et al. 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;291(6):E1290-E1294. PMID: 16822960. DOI: 10.1152/ajpendo.00201.2006

6. Prakash A, Goa KL. Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. BioDrugs. 1999;12(2):139-157. PMID: 18031173. DOI: 10.2165/00063030-199912020-00007

7. Ishida J, Saitoh M, Doehner W, von Haehling S, Anker SD, Springer J. Growth hormone secretagogues: history, mechanism of action, and clinical development. JCSM Rapid Commun. 2020;3(1):25-37. DOI: 10.1002/rco2.9