CJC-1295: Research Chemistry and Literature

Origin and identification

The engineering strategy behind CJC-1295 predates the compound itself. Campbell and colleagues reported in 1994 that hGRF(1-29) type analogues could be stabilised against enzymatic and chemical degradation by substituting the residues responsible for each degradation route: the amino terminal region cleaved by dipeptidyl peptidase IV, an internal asparagine prone to deamidation and rearrangement, and a carboxy terminal methionine subject to oxidation. Analogues carrying this substitution pattern were several fold more potent than native GRF(1-29) in cultured rat pituitary cells and in pigs, establishing that a stabilised backbone could outperform the native sequence rather than merely survive longer.

CJC-1295 itself was introduced by Jette and colleagues at ConjuChem in 2005. Working from a stabilised hGRF(1-29) backbone, they synthesised three maleimide functionalised derivatives and reacted each ex vivo with human serum albumin, exploiting the single free thiol at cysteine 34. The lead compound, named CJC-1295, formed a stable covalent conjugate and remained detectable in rat plasma beyond 72 hours, compared with a native hGRF(1-29) half-life ordinarily measured in minutes. Receptor activation was confirmed directly in the same rats: the albumin bound conjugate still triggered the GRF receptor on the anterior pituitary, showing that the bulky carrier did not block receptor engagement.

Preclinical research context

The clearest in vivo demonstration of biological activity comes from a growth hormone releasing hormone knockout mouse. Alba and colleagues reported in 2006 that once daily administration of the DAC conjugated compound to these animals, which lack endogenous GHRH signalling entirely, normalised longitudinal growth relative to untreated knockout littermates, approaching the trajectory of wild type controls. Because the knockout background removes the native ligand, any growth response in that model is attributable to the analogue engaging the GHRH receptor directly rather than amplifying an existing signal.

Plasma stability is the axis that separates the two forms most sharply. Reported pharmacokinetic data put the elimination half-life of the DAC conjugated form at 5.8 to 8.1 days, several orders of magnitude longer than the half-life reported for unconjugated hGRF(1-29) type analogues, which is measured in minutes because the unprotected amino terminus is rapidly cleaved once in circulation. That extended residence does not convert the receptor into a tonic switch: reported pharmacological data show that continuous engagement over several days preserves the normal pulsatile pattern of growth hormone secretion, with pulse frequency and amplitude essentially unchanged while trough, or interpulse, concentrations rise substantially and lift the overall mean level. The receptor itself, GHRHR, is a class B G protein coupled receptor expressed on pituitary somatotrophs, and the DAC modification does not appear to change how the ligand engages it, only how long the ligand remains available to do so.

Analytical characterisation

Purity is established by reverse phase HPLC. A C18 stationary phase with a water and acetonitrile gradient in dilute trifluoroacetic acid separates the main peak from truncated sequences and deamidation products, and area percent at 214 nanometres reports the peptide backbone directly. The two forms elute distinctly: the added lysine and maleimide linked group on the DAC bearing peptide shift retention later and increase the hydrophobic character of the molecule relative to the unconjugated backbone.

Identity is confirmed by mass spectrometry. Electrospray ionisation of a peptide in the 3300 to 3700 dalton range produces a multiply charged envelope that deconvolutes to an average mass compared against the two calculated values above; the roughly 279 dalton difference between the unconjugated backbone and the DAC bearing form corresponds to the added lysine and maleimidopropionyl linked group and is used to confirm which form a given lot contains. Certificates of Analysis for material listed here are issued by Janoshik Analytical and report identity and chromatographic purity for the specific lot shipped, alongside net peptide content.

Handling and storage

The lyophilised powder tolerates ambient conditions during transit, in either form. Shipping without a cold chain is ordinary practice for material of this class and does not compromise a vial that arrives sealed and intact. Check the seal and the desiccant on arrival before anything else.

Store the sealed vial at minus 20 degrees Celsius, in the dark, on receipt. Let it reach room temperature before opening to avoid condensation settling on the powder, which is the most common route by which a dry peptide of this size takes up water it was never meant to hold.

Reconstituted material is a different proposition. Hold it at 2 to 8 degrees Celsius and treat its useful window as short, particularly for the DAC bearing form, where the reactive maleimide group is consumed on contact with albumin or with any other free thiol in the buffer and cannot be regenerated once spent. Divide solution into single-use aliquots before the first freeze rather than returning a stock vial to the freezer repeatedly, and record the date each aliquot was prepared.

References

1. Enhanced stability and potency of novel growth hormone-releasing factor (GRF) analogues derived from rodent and human GRF sequences
2. 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
3. Once-daily administration of CJC-1295, a long-acting growth hormone-releasing hormone (GHRH) analog, normalizes growth in the GHRH knockout mouse
4. 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
5. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog
6. CJC1295 Without DAC, PubChem Compound Summary CID 91976842
7. Cjc 1295, PubChem Compound Summary CID 91971820

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