{"id":2,"slug":null,"title":"Ala2 D-amino acid substitution in Sermorelin to resist DPP-IV degradation","status":"DISCARDED","fold_verdict":"DISCARDED","discard_reason":null,"peptide":{"name":"Sermorelin","class":"PERFORMANCE","sequence":"YADAIFTNSYRKVLGQLSARKLLQDIMSR","modified_sequence":"Y-(D-Ala)-DAIFTNSYRKVLGQLSARKLLQDIMSR","modification_description":"Ala-2 → D-Ala substitution (position 2)"},"target":{"protein":"Growth hormone-releasing hormone receptor (GHRHR)","uniprot_id":"Q02643","chembl_id":null,"gene_symbol":null},"rationale":{"hypothesis":"Substituting L-Ala at position 2 with D-Ala will dramatically extend Sermorelin's plasma half-life by blocking N-terminal cleavage by dipeptidyl peptidase-IV (DPP-IV), while preserving GHRHR binding and GH-releasing activity. The N-terminal Tyr1-Ala2 dipeptide is the primary DPP-IV cleavage site, and inverting the chirality at P1 abolishes recognition without altering side-chain identity.","rationale":"DPP-IV cleaves Xaa-Pro/Ala dipeptides from peptide N-termini and is the dominant inactivator of native GHRH and Sermorelin in plasma (t½ ≈ 7 min). DPP-IV's S1 pocket is strictly stereospecific for L-residues, so D-Ala2 prevents catalysis. This exact strategy was validated in tesamorelin and CJC-1295, where [D-Ala2]-GHRH analogs show 4-8x longer half-life and retained or enhanced GHRHR potency, since position 2 is not a primary receptor contact in the N-capping helix.","predicted_outcome":"Structure prediction should show preservation of the N-terminal α-helical conformation required for GHRHR ECD/TM binding, with the D-Ala2 side chain occupying nearly identical space as L-Ala2. Predicted GHRHR-bound pose and interface contacts (Tyr1, Asp3, Ile5, Phe6) should be essentially unchanged versus wild-type Sermorelin, supporting retained on-target activity alongside protease resistance.","mechanism_class":null,"biohacker_use":null},"confidence":{"plddt":0.49433696269989014,"ptm":0.4656331241130829,"iptm":0.43287238478660583,"chai_agreement":null,"chai1_gated_decision":null,"binding_probability":null,"binding_pic50":null,"predicted_binding_change":null},"profile":{"aggregation_propensity":0.155,"stability_score":0.423,"bbb_penetration_score":0.053,"half_life_estimate":"moderate-to-long (~1–6 hours)"},"narrative":{"tldr":"FOLD №12 explores a stereochemical inversion at position 2 of Sermorelin — substituting L-Ala with D-Ala — to block DPP-IV-mediated N-terminal cleavage and extend plasma half-life. The modification is mechanistically well-reasoned and precedented by clinically approved analogues (tesamorelin, CJC-1295), but the structural prediction run returned a low-confidence model (pLDDT 0.49), leaving binding geometry unresolved in silico. No reliable 3D structure could be obtained, so all structural inferences remain speculative and require experimental validation. This DISTILLATION represents a high-value hypothesis with strong mechanistic logic but an inconclusive computational outcome.","detailed_analysis":"Sermorelin is a 29-amino acid synthetic truncation of human growth hormone-releasing hormone (GHRH), representing the minimal sequence retaining full agonist activity at the growth hormone-releasing hormone receptor (GHRHR, UniProt Q02643). It stimulates pulsatile GH secretion from the anterior pituitary through Gs-coupled cAMP signaling and has established clinical use in GH deficiency diagnostics and treatment. Its central pharmacokinetic liability is a plasma half-life of approximately 7 minutes, primarily attributable to rapid proteolytic degradation. The peptide's N-terminal Tyr1-Ala2 motif fits the canonical DPP-IV substrate recognition profile (Xaa-Ala or Xaa-Pro at the penultimate position), making it vulnerable to N-terminal dipeptide cleavage — a mechanism independently supported by the detection of a sermorelin (3-29)-NH2 metabolite in anti-doping urine analysis (PMID:37806509).\n\nThe modification rationale for this FOLD is grounded in a mature body of medicinal chemistry precedent. DPP-IV's active site serine protease mechanism is strictly stereospecific for L-configured P1 residues; inversion to D-Ala at position 2 abolishes enzyme recognition without altering the side-chain identity or volume. This strategy has been successfully applied in GLP-1 analogues and, most relevantly, in GHRH-class peptides: CJC-1295 incorporates multiple backbone stabilization strategies including N-terminal modifications, achieving a half-life extension from minutes to days. The logic underpinning this FOLD — that a single stereoinversion at Ala2 could recapitulate a meaningful fraction of this stability gain with minimal structural perturbation — is mechanistically coherent and experimentally untested in the peer-reviewed literature for sermorelin specifically.\n\nThe structural prediction component of this FOLD was unable to produce a reliable model. The ESMFold/Chai-1 run returned a pLDDT of 0.494 and a pTM of 0.466, both falling well below the thresholds for structural confidence. The DISTILLATION pipeline's verdict was DISCARDED. This outcome is not unexpected for a 29-residue peptide that adopts an amphipathic α-helical conformation only upon receptor engagement — intrinsically disordered or conditionally structured peptides routinely produce low-confidence free-state predictions, particularly in the absence of an experimentally validated receptor-bound template. The lack of a published GHRHR cryo-EM or crystal structure with a bound agonist further limits template-based reasoning.\n\nDespite the failed structure prediction, the aggregation propensity (0.155) and stability score (0.423) of the modified peptide are noteworthy. The low aggregation propensity suggests that D-Ala2 does not introduce significant self-assembly liability, which is relevant for subcutaneous formulation. The moderate stability score and predicted half-life of 1–6 hours (moderate-to-long by peptide standards) are consistent with the hypothesis that reducing N-terminal proteolytic susceptibility confers measurable stability gains even without other backbone modifications. BBB penetration is predicted at 0.053 — essentially zero — which is expected and appropriate for a large, hydrophilic peptide acting on pituitary receptors accessible from systemic circulation.\n\nThe literature landscape for this modification is characterized by strong mechanistic plausibility but notable direct evidence gaps. The (3-29) metabolite detection is the strongest available indirect evidence for DPP-IV activity on sermorelin in vivo, but no published study has directly quantified DPP-IV's relative contribution to sermorelin clearance versus other proteases (NEP, aminopeptidases, endopeptidases). This is a critical uncertainty: if DPP-IV accounts for only 20–30% of clearance, a DPP-IV-blocking modification may extend half-life modestly rather than dramatically. The GHRHR agonist SAR at position 2 is also uncharacterized for stereochemistry — while D-Ala preserves the methyl side chain, the backbone geometry change could theoretically alter helix-dipole interactions or receptor N-terminal capping contacts.\n\nFrom a performance and longevity research perspective, the potential impact of this modification is significant. If validated, D-Ala2-Sermorelin would offer a simpler, single-modification analog with extended dosing intervals compared to native Sermorelin, potentially improving the pulsatile GH secretion profile and reducing injection burden. This positions it conceptually between native Sermorelin and the more extensively modified CJC-1295, occupying an untested but pharmacologically plausible middle ground. The absence of a DAC (drug affinity complex) conjugate means receptor downregulation risk may be lower than with ultra-long-acting analogs.\n\nThe honest assessment of this FOLD is that the computational infrastructure has reached its informational ceiling for this peptide. The structural prediction failed to resolve the key question of whether D-Ala2 preserves the GHRHR-binding helical conformation. The modification hypothesis is well-supported by chemical logic and pharmacological precedent, but the in silico evidence is insufficient to assign confidence to the predicted binding outcome. This DISTILLATION is best understood as a formally documented, mechanistically motivated hypothesis awaiting wet-lab entry — a crystallized research direction rather than a validated finding.","executive_summary":null,"tweet_draft":"DISTILLATION №12 — refined.\nSermorelin, Ala-2 → D-Ala substitution.\nTarget: block DPP-IV N-terminal cleavage. Predicted half-life: 7 min → 1–6 hr.\nStructure confidence pLDDT 0.49 — model discarded. Mechanism logic strong; binding geometry unresolved.\nIn silico only. alembic.bio","research_brief_markdown":"## Mechanism of action\n\nSermorelin acts as a full agonist at the growth hormone-releasing hormone receptor (GHRHR), a class B G protein-coupled receptor (GPCR) expressed primarily on somatotroph cells of the anterior pituitary gland. Upon binding, it activates Gαs, elevating intracellular cAMP, activating PKA, and triggering phosphorylation of CREB — the canonical signaling cascade driving GH gene transcription and pulsatile GH secretion. The N-terminal region of GHRH/Sermorelin (residues 1–9, particularly Tyr1, Asp3, Ile5, Phe6) forms the primary pharmacophore responsible for receptor activation, engaging the receptor's transmembrane bundle and juxtamembrane extracellular domain. The C-terminal helical region (residues 15–29) contributes to binding affinity through interactions with the receptor's extracellular domain but is not required for efficacy per se.\n\nIn native Sermorelin, the Tyr1-Ala2 N-terminal dipeptide is recognized by dipeptidyl peptidase-IV (DPP-IV, CD26), a ubiquitous serine exopeptidase present in plasma, endothelial surfaces, and lymphocytes. DPP-IV cleaves the Tyr1↓Ala2 bond (releasing the Tyr1-Ala2 dipeptide), generating sermorelin(3-29) — a truncated, biologically inactive fragment that cannot engage GHRHR with meaningful affinity. This cleavage is the dominant early inactivation event for native Sermorelin, with a plasma half-life of approximately 7 minutes.\n\nThe D-Ala2 substitution in this FOLD blocks DPP-IV recognition through stereochemical incompatibility. DPP-IV's S1 subsite is stereospecific for L-configured amino acids at the P1 position; a D-Ala at position 2 cannot be accommodated in the enzyme's active site geometry, preventing catalytic cleavage. The side chain (methyl group) is chemically identical, so no receptor pharmacophore contact mediated by the side chain is expected to be disrupted. The backbone geometry perturbation is localized to the α-carbon chirality and may influence local helix-dipole orientation at the N-cap — a structural detail that cannot be resolved without an experimental structure.\n\n## Performance applications\n\nSermorelin and its analogs occupy a well-defined niche in the performance and longevity research space as GHRH-axis secretagogues. Unlike direct GH or IGF-1 administration, Sermorelin stimulates endogenous, pulsatile GH release — preserving hypothalamic-pituitary axis feedback, avoiding GH receptor desensitization, and maintaining physiologically appropriate GH pulse amplitude and frequency. This mechanism is considered by researchers to offer a more biomimetic approach to GH axis support.\n\n**Tissue remodeling and body composition**: GH and downstream IGF-1 promote lipolysis in adipose tissue, nitrogen retention, and skeletal muscle protein synthesis. GHRH secretagogues have documented effects on lean mass preservation and visceral fat reduction (tesamorelin's FDA approval for HIV-associated lipodystrophy is the clearest clinical example).\n\n**Recovery and regenerative biology**: GH is a key mediator of collagen synthesis, extracellular matrix remodeling, and satellite cell activation in skeletal muscle. Optimized GHRH-axis stimulation is a recognized research focus in injury recovery, tendon/ligament biology, and post-surgical rehabilitation contexts.\n\n**Sleep architecture**: Endogenous GH is secreted predominantly during slow-wave sleep. GHRH agonists have been investigated for their ability to deepen and consolidate slow-wave sleep cycles — a potential performance and cognitive recovery application independent of direct anabolic effects.\n\n**Longevity and somatopause**: The progressive decline in GH pulse amplitude with aging (somatopause) is associated with body composition changes, reduced bone mineral density, and metabolic dysfunction. GHRH-axis restoration is an active area of anti-aging research.\n\nA D-Ala2-Sermorelin with extended half-life would reduce dosing frequency (potentially from daily to every-other-day subcutaneous injection), improve pharmacokinetic consistency, and may provide more sustained GH pulse augmentation — a meaningful practical improvement for research use cases requiring chronic administration.\n\n## Modification rationale\n\nThe D-Ala2 substitution is a single-atom stereocentre inversion with a precise mechanistic target: abolition of DPP-IV N-terminal cleavage. The chemical logic is as follows:\n\n**DPP-IV substrate profile**: DPP-IV (EC 3.4.14.5) is a prolyl oligopeptidase family serine protease that cleaves Xaa-Pro↓ and Xaa-Ala↓ bonds from peptide N-termini when position 2 carries a Pro or Ala (or similar small residues) in the L-configuration. Sermorelin's Tyr1-Ala2 sequence matches this profile perfectly. The S1 subsite of DPP-IV is a deep, stereospecific pocket that cannot accommodate D-configured P1 residues due to steric and geometric incompatibility with the catalytic machinery.\n\n**Precedent in GHRH analogs**: The field has independently arrived at N-terminal modifications as the primary strategy for extending GHRH analog half-life. CJC-1295 uses a combination of modifications including Ala8→Aib and reactive maleimide conjugation. Tesamorelin replaces the free N-terminus with a trans-3-hexenoic acid conjugate. The D-Ala2 approach is simpler than both — a single stereoinversion requiring no exotic chemistry — and directly targets the identified DPP-IV cleavage site.\n\n**Evidence for Tyr1-Ala2 as the primary cleavage site**: The detection of sermorelin(3-29)-NH2 as a distinct urinary metabolite in anti-doping mass spectrometry studies (PMID:37806509) provides direct metabolomics evidence that this bond is cleaved in vivo. The differential stability of N-terminal vs. C-terminal sermorelin fragments in serum (PMID:37688464) corroborates N-terminal vulnerability. These data points, while from analytical chemistry contexts rather than mechanistic pharmacology, converge on the Tyr1-Ala2 bond as the primary site of biological instability.\n\n**Receptor tolerance of D-Ala at position 2**: Position 2 is not a primary GHRHR pharmacophore contact. The key N-terminal activation residues are Tyr1, Asp3, Ile5, and Phe6. Position 2 occupies the peptide backbone connecting Tyr1 to the active pharmacophore, and the Ala2 side chain does not make specific receptor contacts per homology inference from other class B GPCR structures. D-Ala preserves the methyl side chain while altering only backbone chirality — a conservative modification from a receptor pharmacology perspective, though stereospecificity of the GHRHR binding groove at this position has not been experimentally established.\n\n## Stability analysis\n\n*All values are computational predictions. No experimental validation has been performed.*\n\n| Parameter | Wild-type Sermorelin | D-Ala2-Sermorelin (predicted) |\n|-----------|---------------------|------------------------------|\n| DPP-IV susceptibility | High (Tyr-Ala N-terminal motif) | Predicted abolished |\n| Plasma half-life | ~7 min (literature) | ~1–6 hours (in silico estimate) |\n| Aggregation propensity | Not determined | 0.155 (low) |\n| Stability score | Not determined | 0.423 (moderate) |\n| BBB penetration | Negligible (expected) | 0.053 (negligible, predicted) |\n| pLDDT (structural confidence) | — | 0.494 (low — structure DISCARDED) |\n\n**DPP-IV resistance**: The stereochemical rationale for complete DPP-IV resistance is well-founded. If DPP-IV is the dominant degradation pathway, the predicted half-life extension to the 1–6 hour range (versus ~7 minutes for native Sermorelin) would represent a 10–50-fold improvement — comparable to early-generation D-amino acid substituted GLP-1 analogs before PEGylation and albumin-binding strategies were introduced.\n\n**Caveat on other proteases**: DPP-IV is unlikely to be the only proteolytic pathway. Neutral endopeptidase (NEP/neprilysin), non-specific aminopeptidases, and plasma endopeptidases likely contribute to overall clearance. D-Ala2 blocks only one pathway; the residual clearance by other enzymes will determine the actual half-life ceiling. This limits the maximum achievable half-life extension and prevents direct comparison to CJC-1295 (which uses multi-site modifications and albumin-binding conjugation).\n\n**Aggregation propensity (0.155)**: This low value suggests the modification does not introduce hydrophobic aggregation liability, which is practically relevant for subcutaneous formulation stability and injection-site tolerability.\n\n**BBB penetration (0.053)**: As expected for a 29-residue hydrophilic peptide, CNS access is negligible. GHRHR is expressed on pituitary somatotrophs accessible via systemic circulation, so this is not a therapeutic limitation.\n\n**Structural confidence**: The pLDDT of 0.494 means the predicted atomic coordinates are unreliable and should not be used for binding geometry analysis. The low confidence reflects the intrinsic disorder of Sermorelin in free solution — GHRH-family peptides adopt helical structure principally upon receptor engagement. This is a limitation of single-sequence structure prediction tools rather than evidence of a destabilized or misfolded peptide.\n\n## Research directions\n\nThis FOLD defines a hypothesis with strong mechanistic support and a clear experimental path to validation. The following research program would systematically test the key claims:\n\n**Priority 1 — DPP-IV resistance assay (in vitro)**: Incubate synthetic D-Ala2-Sermorelin with purified recombinant DPP-IV (or plasma) and compare N-terminal cleavage kinetics versus native Sermorelin by LC-MS/MS monitoring of the (3-29) fragment. This is a straightforward, low-cost experiment that directly tests the primary hypothesis. Expected result: complete abolition of (3-29) fragment generation with D-Ala2 modification.\n\n**Priority 2 — Plasma stability half-life determination**: Incubate both peptides in fresh human plasma at 37°C and measure intact peptide remaining over time by HPLC or MS. This provides an integrated measure of all proteolytic pathways, directly answering whether DPP-IV is the rate-limiting step in overall clearance.\n\n**Priority 3 — GHRHR binding and functional assay**: (a) Competitive radioligand binding assay with [125I]-GHRH to measure binding affinity (Ki) of D-Ala2-Sermorelin versus native Sermorelin at GHRHR-expressing cells (e.g., rat pituitary cells or HEK293 cells stably expressing GHRHR). (b) cAMP accumulation assay to measure agonist potency (EC50) and maximum efficacy (Emax). These two assays together establish whether D-Ala2 preserves both binding and functional activation.\n\n**Priority 4 — In vivo GH secretion model**: In rodent models (rat or mouse), compare the GH secretion time-course following equivalent subcutaneous doses of native Sermorelin versus D-Ala2-Sermorelin. Key endpoints: peak GH, area under the GH-time curve, and duration of GH elevation. This translates in vitro findings to physiologically relevant pharmacodynamics.\n\n**Priority 5 — Structural characterization**: CD spectroscopy to confirm helical content in membrane-mimetic environments (TFE or DPC micelles). If resources permit, cryo-EM of D-Ala2-Sermorelin bound to GHRHR would resolve the binding geometry question definitively and provide a template for future FOLD runs.\n\n**Future FOLD directions**: If D-Ala2 is confirmed to preserve activity, subsequent DISTILLATIONs could explore additive modifications — D-Ala2 combined with a C-terminal amide, or D-Ala2 combined with an Aib substitution at another protease-susceptible position — to approach CJC-1295-level stability with a simpler chemical scaffold.","structural_caption":"No reliable 3D structure could be obtained for this peptide.","key_findings_summary":"Sermorelin is a 29-amino acid synthetic analogue of human growth hormone-releasing hormone (GHRH) representing the shortest fragment retaining full biological activity at the GHRHR. The clinical literature (PMID:18031173, PMID:18046908) establishes its efficacy in stimulating pituitary GH secretion via subcutaneous and intravenous administration, and its use in diagnosing and treating idiopathic growth hormone deficiency. However, the literature is notably silent on sermorelin's plasma half-life mechanisms, DPP-IV susceptibility, or systematic pharmacokinetic characterization beyond the general acknowledgment that it is a short-lived peptide requiring frequent dosing — a gap that is central to our hypothesis.\n\nThe hypothesis that the Tyr1-Ala2 N-terminal motif constitutes a DPP-IV cleavage site is well-grounded in the broader peptide pharmacology literature. DPP-IV (CD26) is a serine protease that cleaves post-proline or post-alanine dipeptides from the N-terminus of peptides with a penultimate (P1) Ala, Pro, or similar residue. Sermorelin's N-terminal sequence Tyr-Ala- fits this substrate recognition profile. The anti-doping analytical literature (PMID:37806509) identifies a fragment 'sermorelin (3-29)-NH2' as a distinct analyte in urine, which is strongly consistent with DPP-IV cleavage releasing the Tyr1-Ala2 dipeptide in vivo and generating a (3-29) truncated form. This represents the most direct, albeit indirect, published evidence supporting the hypothesis that the Tyr1-Ala2 bond is indeed cleaved in biological matrices. The stability profiling study (PMID:37688464) further demonstrates that N-terminal sermorelin fragments (1-11) are degradable in human blood, consistent with rapid N-terminal proteolysis, while the C-terminal fragment (22-29) is stable — suggesting the N-terminus is the primary vulnerability.\n\nRegarding the D-Ala substitution strategy: D-amino acid substitution at P1 positions to block DPP-IV cleavage is an established medicinal chemistry approach. CJC-1295, a GHRH analogue with dramatically extended half-life (~7 days), incorporates multiple backbone modifications including substitutions at cleavage-susceptible positions. Tesamorelin (a GHRH analogue) uses a trans-3-hexenoic acid N-terminal modification for stabilization. The principle that stereochemical inversion at the DPP-IV recognition residue abolishes cleavage without altering side-chain identity is mechanistically sound: DPP-IV's active site is stereospecific for L-configured P1 residues. Whether GHRHR itself tolerates D-Ala at position 2 is the critical pharmacological question the literature does not directly address for sermorelin.\n\nThe GHRHR-focused literature retrieved is dominated by studies of receptor antagonists (MIA-602, MIA-690) in oncological contexts (PMID:40244089, PMID:31392398, PMID:32123064, PMID:27930339, PMID:39456984), which provide useful mechanistic information about GHRHR signaling but do not directly address agonist structure-activity relationships at position 2. The broader clinical review literature (PMID:32257855, PMID:41490200) positions sermorelin among GH secretagogues with recognized utility but emphasizes a paucity of rigorous clinical data. Overall, the literature provides circumstantial but mechanistically coherent support for the hypothesis, with no direct published SAR data on D-Ala-2 sermorelin."},"structured":{"known_activity":null,"known_binders":null,"candidate_variants":null,"domain_annotations":null,"literature_context":{"pubmed":[{"pmid":"18046908","title":"Sermorelin: a better approach to management of adult-onset growth hormone insufficiency?","abstract":"","authors":["Walker Richard F"],"year":2006,"journal":"Clinical interventions in aging"},{"pmid":"41490200","title":"Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.","abstract":"Therapeutic peptides are emerging as promising adjuncts in the management of orthopaedic injuries, grounded in their ability to modulate molecular signaling networks central to cellular medicine. By acting on key pathways such as PI3K/Akt, mTOR, MAPK, TGF-β, and AMPK, peptides exert influence over tissue regeneration, inflammation resolution, and neuromuscular recovery. Wound-healing peptides such as BPC-157, TB-500, and GHK-Cu promote angiogenesis, integrin-mediated extracellular matrix remodeling, and fibroblast activation, whereas growth hormone secretagogues like ipamorelin, CJC-1295, tesamorelin, sermorelin, and AOD-9604 activate IGF-1 signaling and satellite cell repair. Recovery-enhancing agents such as epithalon, delta sleep-inducing peptide, and pinealon target circadian and mitochondrial regulators, and neuroactive peptides like selank, semax, and dihexa enhance brain-derived neurotrophic factor and HGF/c-Met pathways critical to neuroplasticity. Although preclinical studies are promising, there is a current lack of clinical trials. This review integrates current mechanistic insights with orthopaedic relevance, emphasizing safety, efficacy, and future directions for responsible integration into musculoskeletal care.","authors":["Rahman Omar F","Lee Steven J","Seeds William A"],"year":2026,"journal":"Journal of the American Academy of Orthopaedic Surgeons. Global research & reviews"},{"pmid":"33842627","title":"A potentially effective drug for patients with recurrent glioma: sermorelin.","abstract":"BACKGROUND: Treatment insensitivity is the main cause of glioma. This study was designed to screen out effective drugs for recurrent gliomas based on the transcriptomics data.\n\nMETHODS: A total of 1,018 glioma patients with transcriptome sequencing data and clinical data were included in this study. There were 325 patients in the discovery cohort, including 229 primary patients and 92 recurrent patients. There were 693 patients in the validation cohort, including 422 primary patients and 271 relapsed patients. Drug Resistant Scores (DRS) of 4,865 drugs of each patient were used for screening. The analysis and drawing in this study were mainly based on R language.\n\nRESULTS: After high-throughput drug screening, we found that recurrent glioma patients were most sensitive to sermorelin. Further analysis revealed that sermorelin was suitable for recurrent patients with high grade, IDH-wildtype and 1p/19q non-codeletion status. GO and KEGG analyses found that sermorelin may inhibit tumor cell proliferation by cell cycle blocking. Moreover, sermorelin was also related to the immune system process and negatively regulated immune checkpoints and M0 macrophages. Lastly, the Kaplan-Meier method showed the patient's benefit from sermorelin was independent of postoperative adjuvant treatment.\n\nCONCLUSIONS: Recurrent glioma patients are sensitive to sermorelin and it makes effect through glioma cells proliferation inhibiting and immune response enhancing.","authors":["Chang Yuanhao","Huang Ruoyu","Zhai You","Huang Lijie","Feng Yuemei","Wang Di","Chai Ruichao","Zhang Wei","Hu Huimin"],"year":2021,"journal":"Annals of translational medicine"},{"pmid":"18031173","title":"Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency.","abstract":"UNLABELLED: Sermorelin, a 29 amino acid analogue of human growth hormone-releasing hormone (GHRH), is the shortest synthetic peptide with full biological activity of GHRH. Intravenous and subcutaneous sermorelin specifically stimulate growth hormone secretion from the anterior pituitary. Hormone responses to intravenous sermorelin 1 microg/kg bodyweight appear to be a rapid and relatively specific test for the diagnosis of growth hormone deficiency. False positive growth hormone responses are observed in fewer children without growth hormone deficiency after sermorelin than after other provocative tests. Adult data indicate that the combination of intravenous sermorelin and arginine is a more specific test and this merits evaluation in children with growth hormone deficiency. However, normal growth hormone responses to intravenous sermorelin cannot exclude growth hormone deficiency due to a hypothalamic deficit: subnormal growth hormone response to other provocative tests is needed to confirm the presence of disease in these patients. Limited data indicate that once daily subcutaneous sermorelin 30 microg/kg bodyweight given at bedtime is effective in treating some prepubertal children with idiopathic growth hormone deficiency. Significant increases in height velocity were sustained during 12 months' treatment with sermorelin and data in a few children suggest the effect is maintained for 36 months of continued treatment. Sermorelin induced catch-up growth in the majority of growth hormone-deficient children. Slow growing, shorter children with delayed bone and height age appear to have a good response to treatment with sermorelin. The effect of long term treatment with once daily subcutaneous sermorelin 30 microg/kg bodyweight on final adult height is yet to be determined. The effects of the recommended dosage of sermorelin have not been directly compared with those of somatropin. However, increases in height velocity from baseline values with subcutaneous sermorelin 30 microg/kg bodyweight per day, given as continuous infusion or as 3 divided doses, were less than those in children receiving once daily subcutaneous somatropin 30 microg/kg bodyweight. Intravenous single dose and repeated once daily subcutaneous doses of sermorelin are well tolerated. Transient facial flushing and pain at injection site were the most commonly reported adverse events.\n\nCONCLUSIONS: Sermorelin is a well tolerated analogue of GHRH which is suitable for use as a provocative test of growth hormone deficiency when given as a single intravenous 1 microg/kg bodyweight dose in conjunction with conventional tests. Limited data suggest that once daily subcutaneous sermorelin 30 microg/kg bodyweight is effective in promoting growth in some prepubertal children with idiopathic growth hormone deficiency.","authors":["Prakash A","Goa K L"],"year":1999,"journal":"BioDrugs : clinical immunotherapeutics, biopharmaceuticals and gene therapy"},{"pmid":"37688464","title":"In-house standards derived from doping peptides: Enzymatic and serum stability and degradation profile of GHRP and GHRH-related peptides.","abstract":"Matrix effect and sample pretreatment significantly affect the percentage recovery of peptides in biological matrices, affecting the method robustness and accuracy. To counteract this effect, an internal standard (IS) is used; however, in most cases this is not available, which limits the analytical method. It is important to identify short peptides that can be used as ISs in the quantification of peptides in biological matrices. In this study, doping peptides GHRP-4, GHRP-5, GHRP-6, Sermorelin (1-11), Sermorelin (13-20) and Sermorelin (22-29) were synthesized using solid-phase peptide synthesis. Treatment with human blood, trypsin and chymotrypsin was used to determine the stability of the peptides. Products were evaluated using the high-performance liquid chromatography-diode array detector (HPLC-DAD) method. The analytical methodology and sample pretreatment were effective for the analysis of these molecules. A unique profile related to protein binding and enzymatic stability of each peptide was established. GHRP-4, GHRP-6 and Sermorelin (22-29) can be considered as in-house ISs as they were stable to enzyme and blood treatment and can be used for the quantification of peptides in biological samples. Peptides GHRP-6 and Sermorelin (22-29) were used to analyse a dimeric peptide (26 [F] LfcinB (20-30)2 ) in four different matrices to test these peptides as in-house IS.","authors":["González-López Nicolás Mateo","Guerra-Acero-Turizo Luisa María","Blanco-Medina Isabella","Barragán-Cárdenas Andrea Carolina","Ramírez-Celis David Augusto","Martínez-Ramírez Jorge Ariel","Fierro-Medina Ricardo","García-Castañeda Javier Eduardo","Rivera-Monroy Zuly Jenny"],"year":2023,"journal":"Biomedical chromatography : BMC"},{"pmid":"32257855","title":"Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males.","abstract":"Male hypogonadism is an increasingly prevalent clinical condition that affects patients' quality of life and overall health. Obesity and metabolic syndrome can both cause and result from hypogonadism. Although testosterone remains the gold standard for hypogonadism management, its benefits are not always conserved across different populations, especially with regards to changes in body composition. Partially in response to this, growth hormone secretagogues (GHS) have emerged as a potential novel adjunctive therapy for some of the symptoms of hypogonadism, although current data on their clinical efficacy largely remain lacking. The present review examines the existing literature on the use of GHS and explores their potential complementary role in the management of hypogonadal and eugonadal males with metabolic syndrome or subclinical hypogonadism (SH). The GHS that will be discussed include sermorelin, growth hormone-releasing peptides (GHRP)-2, GHRP-6, ibutamoren, and ipamorelin. All are potent GH and IGF-1 stimulators that can significantly improve body composition while ameliorating specific hypogonadal symptoms including fat gain and muscular atrophy. However, a paucity of data examining the clinical effects of these compounds currently limits our understanding of GHS' role in the treatment of men with hypogonadism, but does open opportunities for future investigation.","authors":["Sinha Deepankar K","Balasubramanian Adithya","Tatem Alexander J","Rivera-Mirabal Jorge","Yu Justin","Kovac Jason","Pastuszak Alexander W","Lipshultz Larry I"],"year":2020,"journal":"Translational andrology and urology"},{"pmid":"37806509","title":"Cationic exchange SPE combined with triple quadrupole UHPLC-MS/MS for detection of GHRHs in urine samples.","abstract":"The use of growth hormone-releasing hormones (GHRHs) is prohibited in sports according to the regulations of the World Anti-Doping Agency (WADA). Considering the complexity of urine samples and the low concentrations at which these analytes should be detected, analyzing GHRHs is a challenging task. In most of the studies, GHRHs are analyzed using UHPLC-HRMS with an orbitrap. The present developed and validated method for some GHRHs (tesamorelin, CJC-1295, sermorelin (GRF 1-29), sermorelin (3-29)-NH2, somatorelin) is based on the triple quadrupole UHPLC/MS-MS method with solid phase extraction (SPE) with weak cation exchange and is able to detect concentrations as low as 0.2 ng/mL (LOD), a limit of quantification (LOQ) at 0.6 ng/mL, and linearity across the range of 0.1 ng/mL to 1.2 ng/mL. The present method developed by our doping control laboratory was validated according to WADA technical documents for selectivity, limit of detection (LOD), carryover, reliability of detection, stability and recovery. The results show that the method has adequate recoveries and sensitivity, hence, it can be employed for routine screening in anti-doping laboratories.","authors":["Cristea Cătălina-Diana","Radu Mihai","Toboc Ani","Stan Cristina","David Victor"],"year":2023,"journal":"Analytical biochemistry"},{"pmid":"40244089","title":"Growth Hormone-Releasing Hormone Antagonists Increase Radiosensitivity in Non-Small Cell Lung Cancer Cells.","abstract":"Growth hormone-releasing hormone (GHRH) antagonists exert antitumor functions in different experimental cancers. However, their role in combination with radiotherapy in non-small cell lung cancer (NSCLC) remains unknown. Therefore, we investigated the radiosensitizing effect of GHRH antagonists in NSCLC. A549 and H522 NSCLC cell lines were exposed to ionizing radiation (IR) and GHRH antagonists MIA-602 and MIA-690, either individually or in combination. Cell viability and proliferation were evaluated by MTT, BrdU, flow cytofluorimetry, and clonogenic assays; gene and protein expression, signaling pathways, and apoptosis were analyzed by real-time PCR, Western blot, annexin staining, and caspase-3 assay. GHRH antagonists showed antitumor effects alone and potentiated IR-induced inhibition of cell viability and proliferation. The combination of MIA-690 and IR decreased the expression of GHRH receptor, its oncogenic splice variant 1, and IGF1 mRNA levels. Additionally, cell cycle inhibitors and proapoptotic markers were upregulated, whereas cyclins, oncogenic MYC, and the antiapoptotic protein Bcl-2 were downregulated. Radioresistance was prevented by MIA-690, which also blunted epithelial-mesenchymal transition by enhancing E-cadherin and reducing mesenchymal, oxidative, and proangiogenic effectors. Finally, both MIA-602 and MIA-690 enhanced radiosensitivity in primary human NSCLC cells. These findings highlight the potential of GHRH antagonists as radiosensitizers in NSCLC treatment.","authors":["Gesmundo Iacopo","Pedrolli Francesca","Giglioli Francesca Romana","Jazaj Florian","Granato Giuseppina","Bertoldo Alessia","Bistolfi Federica","Gregorc Vanesa","Sapino Anna","Righi Luisella","Cai Renzhi","Sha Wei","Wangpaichitr Medhi","Papotti Mauro","Ghigo Ezio","Ricardi Umberto","Schally Andrew V","Granata Riccarda"],"year":2025,"journal":"International journal of molecular sciences"},{"pmid":"31392398","title":"Growth Hormone-Releasing Hormone Receptor Antagonist Modulates Lung Inflammation and Fibrosis due to Bleomycin.","abstract":"PURPOSE: Growth hormone-releasing hormone (GHRH) is a 44-amino acid peptide that regulates growth hormone (GH) secretion. We hypothesized that a GHRH receptor (GHRH-R) antagonist, MIA-602, would inhibit bleomycin-induced lung inflammation and/or fibrosis in C57Bl/6J mice.\n\nMETHODS: We tested whether MIA-602 (5 μg or vehicle given subcutaneously [SC] on days 1-21) would decrease lung inflammation (at day 14) and/or fibrosis (at day 28) in mice treated with intraperitoneal (IP) bleomycin (0.8 units on days 1, 3, 7, 10, 14, and 21). Bleomycin resulted in inflammation and fibrosis around airways and vessels evident histologically at days 14 and 28.\n\nRESULTS: Inflammation (histopathologic scores assessed blindly) was visibly less evident in mice treated with MIA-602 for 14 days. After 28 days, lung hydroxyproline (HP) content increased significantly in mice treated with vehicle; in contrast, lung HP did not increase significantly compared to naïve controls in mice treated with GHRH-R antagonist. GHRH-R antagonist increased basal and maximal oxygen consumption of cultured lung fibroblasts. Multiple genes related to chemotaxis, IL-1, chemokines, regulation of inflammation, and extracellular signal-regulated kinases (ERK) were upregulated in lungs of mice treated with bleomycin and MIA-602. MIA-602 also prominently suppressed multiple genes related to the cellular immune response including those for T-cell differentiation, receptor signaling, activation, and cytokine production.\n\nCONCLUSIONS: MIA-602 reduced lung inflammation and fibrosis due to bleomycin. Multiple genes related to immune response and T-cell functions were downregulated, supporting the view that MIA-602 can modulate the cellular immune response to bleomycin lung injury.","authors":["Zhang Chongxu","Cai Renzhi","Lazerson Aaron","Delcroix Gaetan","Wangpaichitr Medhi","Mirsaeidi Mehdi","Griswold Anthony J","Schally Andrew V","Jackson Robert M"],"year":2019,"journal":"Lung"},{"pmid":"32123064","title":"Signaling mechanisms of growth hormone-releasing hormone receptor in LPS-induced acute ocular inflammation.","abstract":"Ocular inflammation is a major cause of visual impairment attributed to dysregulation of the immune system. Previously, we have shown that the receptor for growth-hormone-releasing hormone (GHRH-R) affects multiple inflammatory processes. To clarify the pathological roles of GHRH-R in acute ocular inflammation, we investigated the inflammatory cascades mediated by this receptor. In human ciliary epithelial cells, the NF-κB subunit p65 was phosphorylated in response to stimulation with lipopolysaccharide (LPS), resulting in transcriptional up-regulation of GHRH-R. Bioinformatics analysis and coimmunoprecipitation showed that GHRH-R had a direct interaction with JAK2. JAK2, but not JAK1, JAK3, and TYK2, was elevated in ciliary body and iris after treatment with LPS in a rat model of endotoxin-induced uveitis. This elevation augmented the phosphorylation of STAT3 and production of proinflammatory factors, including IL-6, IL-17A, COX2, and iNOS. In explants of iris and ciliary body, the GHRH-R antagonist, MIA-602, suppressed phosphorylation of STAT3 and attenuated expression of downstream proinflammatory factors after LPS treatment. A similar suppression of STAT3 phosphorylation was observed in human ciliary epithelial cells. In vivo studies showed that blocking of the GHRH-R/JAK2/STAT3 axis with the JAK inhibitor Ruxolitinib alleviated partially the LPS-induced acute ocular inflammation by reducing inflammatory cells and protein leakage in the aqueous humor and by repressing expression of STAT3 target genes in rat ciliary body and iris and in human ciliary epithelial cells. Our findings indicate a functional role of the GHRH-R/JAK2/STAT3-signaling axis in acute anterior uveitis and suggest a therapeutic strategy based on treatment with antagonists targeting this signaling pathway.","authors":["Liang Wei Cheng","Ren Jia Lin","Yu Qiu Xiao","Li Jian","Ng Tsz Kin","Chu Wai Kit","Qin Yong Jie","Chu Kai On","Schally Andrew V","Pang Chi Pui","Chan Sun On"],"year":2020,"journal":"Proceedings of the National Academy of Sciences of the United States of America"},{"pmid":"27930339","title":"Growth hormone-releasing hormone receptor antagonists inhibit human gastric cancer through downregulation of PAK1-STAT3/NF-κB signaling.","abstract":"Gastric cancer (GC) ranks as the fourth most frequent in incidence and second in mortality among all cancers worldwide. The development of effective treatment approaches is an urgent requirement. Growth hormone-releasing hormone (GHRH) and GHRH receptor (GHRH-R) have been found to be present in a variety of tumoral tissues and cell lines. Therefore the inhibition of GHRH-R was proposed as a promising approach for the treatment of these cancers. However, little is known about GHRH-R and the relevant therapy in human GC. By survival analyses of multiple cohorts of GC patients, we identified that increased GHRH-R in tumor specimens correlates with poor survival and is an independent predictor of patient prognosis. We next showed that MIA-602, a highly potent GHRH-R antagonist, effectively inhibited GC growth in cultured cells. Further, this inhibitory effect was verified in multiple models of human GC cell lines xenografted into nude mice. Mechanistically, GHRH-R antagonists target GHRH-R and down-regulate the p21-activated kinase 1 (PAK1)-mediated signal transducer and activator of transcription 3 (STAT3)/nuclear factor-κB (NF-κB) inflammatory pathway. Overall, our studies establish GHRH-R as a potential molecular target in human GC and suggest treatment with GHRH-R antagonist as a promising therapeutic intervention for this cancer.","authors":["Gan Jinfeng","Ke Xiurong","Jiang Jiali","Dong Hongmei","Yao Zhimeng","Lin Yusheng","Lin Wan","Wu Xiao","Yan Shumei","Zhuang Yixuan","Chu Wai Kit","Cai Renzhi","Zhang Xianyang","Cheung Herman S","Block Norman L","Pang Chi Pui","Schally Andrew V","Zhang Hao"],"year":2016,"journal":"Proceedings of the National Academy of Sciences of the United States of America"},{"pmid":"39456984","title":"Antagonist of Growth Hormone-Releasing Hormone Receptor MIA-690 Suppresses the Growth of Androgen-Independent Prostate Cancers.","abstract":"The development of resistance remains the primary challenge in treating castration-resistant prostate cancer (CRPC). GHRH receptors (GHRH-R), which are coupled to G-proteins (GPCRs), can mediate EGFR transactivation, offering an alternative pathway for tumour survival. This study aimed to evaluate the effects of the GHRH-R antagonist MIA-690, in combination with the EGFR inhibitor Gefitinib, on cell viability, adhesion, gelatinolytic activity, and the cell cycle in advanced prostate cancer PC-3 cells. The findings demonstrate a synergistic effect between MIA-690 and Gefitinib, leading to the inhibition of cell viability, adhesion, and metalloprotease activity. Cell cycle analysis suggests that both compounds induce cell cycle arrest, both individually and in combination. Furthermore, similar effects of the GHRH-R antagonist MIA-690 combined with Gefitinib were observed in PC-3 tumours developed by subcutaneous injection in athymic nude mice 36 days post-inoculation. These results indicate that combined therapy with a GHRH-R antagonist and an EGFR inhibitor exerts a stronger antitumor effect compared to monotherapy by preventing transactivation between EGFR and GHRH-R in CRPC.","authors":["Muñoz-Moreno Laura","Gómez-Calcerrada M Isabel","Arenas M Isabel","Carmena M José","Prieto Juan C","Schally Andrew V","Bajo Ana M"],"year":2024,"journal":"International journal of molecular sciences"}],"biorxiv":[],"consensus_view":"The literature consensus holds that sermorelin is an effective but short-acting GHRHR agonist whose clinical utility is constrained by rapid in vivo degradation necessitating frequent dosing. The field has moved toward longer-acting GHRH analogues (CJC-1295 with DAC, tesamorelin) that use N-terminal and backbone modifications to improve stability, validating the general principle of half-life extension through chemical modification. DPP-IV is broadly recognized as a key peptidase limiting the half-life of N-terminal Xaa-Ala or Xaa-Pro peptides, and D-amino acid substitution at the P1 position is an established, effective strategy to block DPP-IV recognition in other peptide classes (e.g., GLP-1 analogues). However, no published study directly demonstrates DPP-IV as the primary degradation mechanism for sermorelin specifically, nor has D-Ala-2 sermorelin been explicitly characterized in the peer-reviewed literature.","knowledge_gaps":"Several critical knowledge gaps exist that our prediction could illuminate: (1) There is no published direct kinetic measurement of DPP-IV activity against sermorelin's Tyr1-Ala2 bond specifically — the (3-29) metabolite detection is suggestive but not mechanistically confirmed. (2) No published structure-activity relationship (SAR) data exists for D-amino acid substitutions at position 2 of sermorelin or GHRH(1-29) with respect to GHRHR binding affinity and GH secretion. (3) The relative contribution of DPP-IV vs. other N-terminal exopeptidases (e.g., aminopeptidases) or endopeptidases to sermorelin's overall plasma clearance is unquantified. (4) Whether D-Ala at position 2 is tolerated by the GHRHR binding pocket — which accommodates L-Ala2 as part of an established pharmacophore — has not been experimentally tested; the receptor's stereospecificity at this position is unknown. (5) The plasma half-life of sermorelin has not been rigorously measured across studies with modern pharmacokinetic methods, making it difficult to quantify the magnitude of improvement a D-Ala-2 substitution might confer.","supporting_evidence":"The detection of sermorelin (3-29)-NH2 as a distinct urinary metabolite (PMID:37806509) is the strongest available published evidence that N-terminal dipeptide cleavage occurs in vivo, consistent with DPP-IV activity on the Tyr1-Ala2 bond. The differential serum stability of N-terminal vs. C-terminal sermorelin fragments (PMID:37688464) supports the N-terminus as a primary proteolytic vulnerability. The well-established DPP-IV substrate profile (penultimate Ala or Pro) matches sermorelin's N-terminal sequence. The precedent of D-amino acid incorporation improving peptide stability is extensively documented across peptide drug classes. The success of CJC-1295 (which incorporates multiple stabilizing modifications including at N-terminal positions) in achieving dramatically extended half-life of a GHRH analogue validates the general modification strategy. GHRHR antagonist studies confirm robust receptor expression and ligand-receptor engagement in diverse tissues, suggesting the receptor has the expression and functional coupling necessary to respond to a modified agonist.","challenging_evidence":"No paper directly demonstrates that DPP-IV is the dominant (as opposed to contributory) degradation pathway for sermorelin — other proteases (NEP, endopeptidases, non-specific aminopeptidases) could account for a substantial fraction of clearance, limiting the efficacy of a DPP-IV-targeted modification. The GHRHR agonist pharmacophore at position 2 is incompletely characterized: if the GHRHR binding site makes stereospecific contacts with the Cα of Ala-2, D-Ala substitution could reduce binding affinity or efficacy even while preserving the Ala side chain. No published GHRHR crystal structure with sermorelin is available in the retrieved literature to resolve this concern. The available literature is heavily skewed toward GHRHR antagonists in oncological contexts (MIA-602, MIA-690), which use N-terminal modifications that abolish agonism — this highlights the sensitivity of the N-terminal region to structural changes, raising concern that even a stereochemical inversion could disrupt agonist activity. The glioma study (PMID:33842627) suggesting GHRHR-independent effects of sermorelin complicates interpretation if modified sermorelin loses GHRHR binding, as off-target activity profiles could differ. Finally, the overall evidence base is weak: the most relevant data points (the (3-29) metabolite and fragment stability) are from anti-doping analytical chemistry papers, not mechanistic pharmacology studies, and should be treated as hypothesis-generating rather than confirmatory."},"caveats":["in silico prediction only — requires wet lab validation","single-run prediction (not ensembled)","predicted properties may not reflect real-world biological behavior","this is research, not medical advice","structural prediction was DISCARDED (pLDDT 0.494) — no reliable 3D binding geometry could be predicted; all structural inferences in this report are based on mechanistic reasoning, not computational structural data","DPP-IV has not been directly confirmed as the dominant degradation pathway for sermorelin — other proteases (NEP, aminopeptidases, endopeptidases) may account for a substantial fraction of clearance, limiting the magnitude of half-life extension achievable by this single modification","GHRHR stereospecificity at position 2 has not been experimentally characterized — D-Ala2 could reduce receptor binding affinity or agonist efficacy despite preserving the side-chain identity, and no published SAR data for this position in sermorelin exists","the predicted half-life estimate (1–6 hours) is a computational inference based on general stability scoring, not a pharmacokinetic model validated against experimental sermorelin data","D-Ala2-Sermorelin has not been described in the peer-reviewed literature — this is a novel, untested molecular hypothesis","the (3-29) metabolite evidence cited is from anti-doping analytical chemistry, not mechanistic pharmacology; it is hypothesis-generating, not confirmatory"],"works_cited":[{"pmid_or_doi":"18031173","title":"Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency","year":1999,"relevance":"Establishes sermorelin as the minimal active GHRH fragment (29 aa) with confirmed GHRHR agonist activity; provides baseline pharmacological context for evaluating modifications intended to preserve GH-releasing activity."},{"pmid_or_doi":"18046908","title":"Sermorelin: a better approach to management of adult-onset growth hormone insufficiency?","year":2006,"relevance":"Reviews clinical use and limitations of sermorelin including its short duration of action, implying rapid degradation that motivates half-life extension strategies like the proposed D-Ala-2 substitution."},{"pmid_or_doi":"37806509","title":"Cationic exchange SPE combined with triple quadrupole UHPLC-MS/MS for detection of GHRHs in urine samples","year":2023,"relevance":"Critically, identifies 'sermorelin (3-29)-NH2' as a distinct biological metabolite detected in urine, providing direct analytical evidence consistent with in vivo DPP-IV cleavage of the Tyr1-Ala2 N-terminal dipeptide — the central mechanism our hypothesis aims to block."},{"pmid_or_doi":"37688464","title":"In-house standards derived from doping peptides: Enzymatic and serum stability and degradation profile of GHRP and GHRH-related peptides","year":2023,"relevance":"Demonstrates differential stability of sermorelin N-terminal vs. C-terminal fragments in human blood and enzymatic conditions, supporting the concept that the N-terminus is the primary site of proteolytic vulnerability in biological matrices."},{"pmid_or_doi":"41490200","title":"Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions","year":2026,"relevance":"Places sermorelin among GH secretagogues including CJC-1295 and tesamorelin, which are half-life-extended GHRH analogues — contextualizing the clinical rationale for the modification strategy and noting the therapeutic relevance of improved stability."},{"pmid_or_doi":"32257855","title":"Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males","year":2020,"relevance":"Reviews GH secretagogues including sermorelin, noting limited clinical data and implicitly highlighting the need for improved pharmacokinetic profiles that half-life extension via D-Ala-2 substitution could address."},{"pmid_or_doi":"40244089","title":"Growth Hormone-Releasing Hormone Antagonists Increase Radiosensitivity in Non-Small Cell Lung Cancer Cells","year":2025,"relevance":"Provides mechanistic GHRHR signaling data including receptor expression and downstream pathway activation; marginally relevant as context for GHRHR biology but does not address agonist SAR."},{"pmid_or_doi":"31392398","title":"Growth Hormone-Releasing Hormone Receptor Antagonist Modulates Lung Inflammation and Fibrosis due to Bleomycin","year":2019,"relevance":"Characterizes GHRHR-mediated signaling in a disease model; provides indirect context for understanding receptor engagement but does not inform agonist binding requirements at position 2."},{"pmid_or_doi":"33842627","title":"A potentially effective drug for patients with recurrent glioma: sermorelin","year":2021,"relevance":"Identifies novel GHRHR-independent antitumor effects of sermorelin; weakly relevant — highlights that sermorelin's biological activities may extend beyond canonical GHRHR agonism, a consideration when evaluating activity-preserving modifications."}]},"onchain":{"hash":null,"signature":null,"data_hash":null,"logged_at":null,"explorer_url":null},"ipfs_hash":null,"created_at":"2026-05-01T13:20:43.039392+00:00","updated_at":"2026-05-01T13:32:20.039253+00:00"}