Study wrapper · #252
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.
Editor's note
This is the foundational discovery paper for CJC-1295 — the rat study that identified the compound — and it is a mechanistic in-vivo investigation, not a clinical one. The chemists synthesised three maleimido derivatives of human GHRH(1-29) designed to bond covalently to a free thiol (Cys34) on serum albumin, then showed all three resisted DPP-IV degradation and stimulated GH in cultured rat pituitary cells. Injected into male Sprague-Dawley rats, the best candidate — CJC-1295 — produced a 4-fold larger GH response than unmodified GHRH(1-29) and persisted in plasma beyond 72 hours, with Western blotting confirming it rode on albumin within 15 minutes. This elegantly establishes the drug-affinity-complex strategy that defines CJC-1295: covalent albumin binding to extend half-life. Its limits are inherent — it is a rat and cell-culture study proving a chemistry-and-pharmacokinetics concept, not therapeutic benefit. These are preclinical findings; human data are needed before clinical conclusions can be drawn. Human confirmation of the sustained GH/IGF-1 effect came later in Phase II trials.
Plain-language abstract
This is the original study that created and identified CJC-1295. Peptide drugs often disappear from the blood quickly. To slow this down, the researchers attached a reactive chemical 'hook' to a short version of human growth-hormone-releasing factor (the first 29 amino acids, GHRH(1-29)) so it would latch permanently onto a specific spot on albumin, the most abundant protein in blood. They made three such versions and first showed, in the test tube, that all three resisted a key breakdown enzyme (DPP-IV) and could still trigger growth-hormone release from cultured rat pituitary cells. They then injected each version under the skin of male rats and measured a burst of growth hormone in the blood. The best-performing version, named CJC-1295, produced about four times more growth-hormone output over two hours than the unmodified peptide, and remained detectable in the blood beyond 72 hours. A protein test confirmed that CJC-1295 was attached to albumin within 15 minutes of injection and stayed in circulation for more than a day. This identified CJC-1295 as a stable, active, long-lasting form of the peptide. The work was done in rats and cells and shows how the drug lasts longer; it does not test benefit or safety in humans.