🦠 Immune peptides

The full-length 39-amino-acid adrenocorticotropic hormone, marketed in the United States since 1952 as porcine-derived repository corticotropin injection (Acthar Gel, Purified Cortrophin Gel) for infantile spasms, multiple sclerosis relapses, and other inflammatory conditions.

A 60-amino-acid recombinant plasma kallikrein inhibitor engineered by phage display from a Kunitz domain of tissue factor pathway inhibitor, FDA approved since 2009 as Kalbitor for acute hereditary angioedema attacks, carrying a boxed anaphylaxis warning.

A synthetic 36-amino-acid peptide copied from the HR2 region of HIV-1 gp41 that blocks fusion of the virus with CD4 cells, granted accelerated approval as Fuzeon on March 13, 2003 for treatment-experienced HIV-1 infection and discontinued in the United States in 2025.

A synthetic decapeptide bradykinin B2 receptor antagonist, FDA approved since 2011 (generics since 2019) as a self-administered subcutaneous injection for acute attacks of hereditary angioedema in adults, that failed in ACE-inhibitor angioedema and COVID-19 trials.

A synthetic 14-residue cyclic peptide CXCR4 antagonist, FDA approved since 2023 as Aphexda, given with filgrastim to mobilize hematopoietic stem cells into the blood for collection before autologous transplant in multiple myeloma.

A PEGylated dimer of two cyclic 15-amino-acid compstatin-family peptides that binds complement C3, FDA approved as a subcutaneous infusion for paroxysmal nocturnal hemoglobinuria (2021) and C3 glomerulopathy / primary IC-MPGN (2025) and as an intravitreal injection for geographic atrophy (2023).

Amgen's AMG 531, a thrombopoietin-mimetic peptibody that raises platelet counts by activating the TPO receptor, FDA approved as Nplate since August 22, 2008 for immune thrombocytopenia and since 2021 for the hematopoietic syndrome of acute radiation syndrome.

A synthetic 15-amino-acid macrocyclic peptide that binds complement C5 and blocks terminal complement activation, FDA approved in October 2023 as Zilbrysq, a once-daily subcutaneous injection for acetylcholine receptor antibody-positive generalized myasthenia gravis.

A native 52-amino-acid vasodilator peptide of the calcitonin family, isolated from human pheochromocytoma in 1993 and tested by Japanese investigators as an intravenous infusion for ulcerative colitis, Crohn's disease, stroke and COVID-19 pneumonia without any approved product.

The native 31-residue opioid peptide cleaved from pro-opiomelanocortin in the pituitary and hypothalamus, a mu- and delta-opioid receptor agonist studied by intravenous, intrathecal and epidural routes in small human series around 1980 and never developed into an approved product.

A tripeptide antioxidant composed of glutamate, cysteine, and glycine, central to cellular detoxification, immune function, and oxidative stress defense.

A synthetic eight-amino-acid peptide derived from a Vibrio cholerae toxin fragment, developed as an oral zonulin antagonist and tight-junction regulator for celiac disease, whose Phase 3 trial was stopped after a failed interim analysis in 2022.

A host-defense peptide associated with innate immunity and tissue-response discussions.

A synthetic nine-residue cationic peptide derived from bovine lactoferricin, injected directly into tumors to lyse cancer cells and release antigens, in Phase 2 testing with pembrolizumab in melanoma and as VP-315 in basal cell carcinoma, with no approval anywhere.

An endogenous opioid pentapeptide (Tyr-Gly-Gly-Phe-Met), also called Opioid Growth Factor, studied as a tonic inhibitor of cell proliferation through a non-classical receptor; its small human trials in cancer and autoimmune disease were open-label or terminated, and the one industry development program was abandoned over pharmacokinetics.

A synthetic 12-amino-acid TREM-1 inhibitor peptide derived from TREM-like transcript-1, infused intravenously in septic shock and COVID-19 trials, that did not meet its phase 2b primary endpoint and passed to Genfit in 2026 for a planned liver-failure trial.

An endogenous 11-amino-acid tachykinin encoded by the TAC1 gene that activates the neurokinin-1 receptor in pain, vasodilation and neuroimmune signaling, with no approved product anywhere and only small human provocation studies.

A synthetic pentapeptide (Arg-Lys-Asp-Val-Tyr) reproducing residues 32 to 36 of the thymic hormone thymopoietin, authorized in Italy and produced in China as an immunomodulator but never approved by the FDA after mixed trials in HIV, rheumatoid arthritis and hepatitis B.

An immune-oriented peptide discussed for immunomodulatory signaling and clinical research in infectious disease and oncology-adjacent contexts.

A zinc-dependent nonapeptide hormone secreted by thymic epithelial cells, studied since the 1970s for T-cell differentiation, neuroendocrine signaling, and anti-inflammatory effects, mostly in animal models and older human immunology research.

A vasoactive intestinal peptide associated with neuroimmune and inflammatory signaling discussions.

A synthetic tetrapeptide (Ala-Glu-Asp-Leu) from the Khavinson bioregulator family, attributed to bronchial mucosa and studied in rat lung-injury models and human bronchial epithelial cell cultures, with no human trials.

A synthetic tripeptide (Glu-Asp-Gly) from the Khavinson bioregulator family, marketed as a bronchial peptide but studied by its developers mainly in gastric-ulcer rats, stress models, and a monocyte cell line.

A neuropeptide related to somatostatin that has been studied for anti-inflammatory, neuroendocrine, and cardiovascular effects.

A synthetic tripeptide (Glu-Asp-Pro) from the Khavinson bioregulator family, identified as a minor component of the thymus extract Thymalin and studied in Russian preclinical work for thymic and immune effects in aging.

A short peptide fragment associated with gut-barrier, inflammatory, and tissue-soothing discussions in the peptide market.

The 26-residue principal toxic peptide of European honey bee venom, a cationic amphipathic helix that lyses cell membranes, with a large preclinical anticancer and antimicrobial literature, no FDA-approved product, and marked hemolytic toxicity.

A free-acid N-acetylated analog of the Russian anxiolytic peptide Selank, capped at the N-terminus while retaining the native C-terminal carboxyl, sold in the research market with no published studies of its own.

An N-acetylated, amidated form of Selank designed for enhanced stability and nasal bioavailability, studied for anxiolytic and nootropic effects via tuftsin-related immune modulation.

Sederma's trade name for palmitoyl tetrapeptide-7 (Pal-GQPR, CAS 221227-05-0), a palmitoylated fragment of human immunoglobulin G used in topical cosmetics for reported IL-6-modulating, skin-soothing effects and best known as half of the Matrixyl 3000 blend.

A synthetic peptide associated with anxiolytic and cognitive-interest discussions in nootropic communities.

A splenic polypeptide identified in the 1980s as a near-twin of thymopoietin, differing at a single active-site residue; its bovine sequence runs 49 residues, while the human 48-residue sequence paper was later retracted.

A synthetic dipeptide (Glu-Trp) from the Khavinson bioregulator family, studied for thymic bioregulation and immune system support in aging.

A thymus-derived peptide complex often discussed in immune and longevity circles.

A naturally occurring tetrapeptide, Thr-Lys-Pro-Arg, cut from the Fc region of immunoglobulin G that stimulates macrophage and microglial phagocytosis through neuropilin-1, studied extensively in animal models of demyelination and infection yet never approved anywhere.

A synthetic dipeptide (Lys-Glu) from the Khavinson bioregulator family, studied for thymic and immune system bioregulation and geroprotective effects.

An oral preparation of low-molecular-weight peptides extracted from calf thymus, designated A-6 in the Khavinson bioregulator line, marketed for immune support on the strength of injectable thymus-extract literature rather than any study of the product itself.