--- title: "FDA Removes 12 Peptides from Category 2, LL-37 Derivative Breakthroughs, Dihexa Primate Data, and Pentosan Polysulfate Disease-Modification Evidence: April 26, 2026 | PepTracker Pro Blog" description: "The FDA formally removes 12 peptides from Category 2 ahead of July PCAC hearings, LL-37 derivative research achieves improved stability and efficacy, dihexa produces measurable synaptogenesis in non-human primates, pentosan polysulfate shows 6-month disease modification in OA, and DSIP fusion peptides cross the blood-brain barrier." lang: en json-ld: | [ { "@context": "https://schema.org", "@type": "Organization", "name": "PepTracker Pro", "url": "https://peptrackerpro.com", "logo": "https://peptrackerpro.com/favicon.png", "description": "Evidence-based educational resource dedicated to improving peptide research literacy.", "contactPoint": { "@type": "ContactPoint", "email": "hello@peptrackerpro.com", "contactType": "customer support" }, "sameAs": [] }, { "@context": "https://schema.org", "@type": "Article", "headline": "FDA Removes 12 Peptides from Category 2, LL-37 Derivative Breakthroughs, Dihexa Primate Data, and Pentosan Polysulfate Disease-Modification Evidence: April 26, 2026", "description": "The FDA formally removes 12 peptides from Category 2 ahead of July PCAC hearings, LL-37 derivative research achieves improved stability and efficacy, dihexa produces measurable synaptogenesis in non-human primates, pentosan polysulfate shows 6-month disease modification in OA, and DSIP fusion peptides cross the blood-brain barrier.", "datePublished": "2026-04-26", "dateModified": "2026-04-26", "author": { "@type": "Organization", "name": "PepTracker Pro Research Team", "url": "https://peptrackerpro.com" }, "publisher": { "@type": "Organization", "name": "PepTracker Pro", "logo": { "@type": "ImageObject", "url": "https://peptrackerpro.com/favicon.png" } }, "mainEntityOfPage": { "@type": "WebPage", "@id": "https://peptrackerpro.com/blog/fda-category2-removal-ll37-derivatives-dihexa-primate-pps-disease-modification-april-2026" } }, { "@context": "https://schema.org", "@type": "BreadcrumbList", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "Home", "item": "https://peptrackerpro.com" }, { "@type": "ListItem", "position": 2, "name": "Blog", "item": "https://peptrackerpro.com/blog" }, { "@type": "ListItem", "position": 3, "name": "FDA Removes 12 Peptides from Category 2, LL-37 Derivative Breakthroughs, Dihexa Primate Data, and Pentosan Polysulfate Disease-Modification Evidence: April 26, 2026", "item": "https://peptrackerpro.com/blog/fda-category2-removal-ll37-derivatives-dihexa-primate-pps-disease-modification-april-2026" } ] } ] --- [Skip to main content](#main) **Educational information only.** This site does not provide medical advice. [Read full disclaimer](/disclaimer) [PepTracker Pro](/) [Home](/)[Peptides](/peptides)[Compare](/compare)[Glossary](/glossary)[Blog](/blog)[Calculators](/calculators)[Start Here](/start) [Open the App](https://app.peptrackerpro.com) [Blog](/blog)/ FDA Removes 12 Peptides from Category 2, LL-37 Derivative Breakthroughs, Dihexa Primate Data, and Pentosan Polysulfate Disease-Modification Evidence: April 26, 2026 News & Updates News & Updates # FDA Removes 12 Peptides from Category 2, LL-37 Derivative Breakthroughs, Dihexa Primate Data, and Pentosan Polysulfate Disease-Modification Evidence: April 26, 2026 PepTracker Pro Research Team April 26, 2026 9 min read ## Table of Contents - [FDA Removes 12 Peptides from Category 2: What It Means for Compounding Access](#section-0) - [LL-37 Derivatives: Solving the Stability and Toxicity Problem](#section-1) - [Dihexa: Non-Human Primate Data Shows Measurable Synaptogenesis](#section-2) - [Pentosan Polysulfate: 6-Month Canine OA Data Supports Disease-Modification Potential](#section-3) - [DSIP Fusion Peptides and the Blood-Brain Barrier Challenge](#section-4) - [Regulatory Calendar and Pipeline Watch](#section-5) ## FDA Removes 12 Peptides from Category 2: What It Means for Compounding Access On April 15, 2026, the FDA announced the removal of 12 bulk drug substances from Category 2 of its compounding list: BPC-157, TB-500, LL-37, Dihexa, DSIP, Epithalon, GHK-Cu (injectable), KPV, PEG-MGF, Melanotan II, MOTS-c, and Semax. This follows the February 2026 reclassification that initially returned several peptides to Category 1 compounding eligibility. The April action reflects withdrawn industry nominations from Category 2, not FDA approval or a regulatory endorsement of safety. Each peptide must still pass through the Pharmacy Compounding Advisory Committee (PCAC) review before final compounding eligibility is determined. The PCAC will hold public hearings on July 23–24, 2026 at the FDA White Oak Campus in Silver Spring, Maryland, with both in-person and virtual attendance available. The public comment docket (FDA-2025-N-6895) remains open until July 22, 2026. A second round of PCAC meetings is expected before February 2027 for remaining peptides. The Washington Post and STAT News reported that FDA advisory committee members are expected to be broadly receptive to expanded compounding access, though the committee's recommendations are advisory only — the FDA makes the final determination. ## LL-37 Derivatives: Solving the Stability and Toxicity Problem LL-37, the only human cathelicidin antimicrobial peptide, has long faced translational barriers: reduced efficacy at physiological salt concentrations, susceptibility to proteolytic degradation, and significant cytotoxicity at therapeutic doses. A 2025 review in ACS Biomaterials Science & Engineering systematically catalogued modification strategies that address these limitations — including amino acid substitutions, truncation, cyclization, and lipidation — showing that engineered LL-37 derivatives can achieve improved stability, reduced hemolytic activity, and preserved or enhanced antimicrobial potency. Separately, a study in mSphere demonstrated that native LL-37 retains potency against non-growing (stationary-phase) E. coli, which are typically resistant to conventional antibiotics, though with slower killing kinetics. This finding is significant because persistent, non-growing bacterial populations are a major driver of chronic and recurrent infections. With LL-37 now removed from FDA Category 2 and scheduled for PCAC review in July 2026, the regulatory pathway for compounded LL-37 preparations is entering a critical window. Ongoing preclinical work on nanocarrier delivery systems and synergistic antibiotic combinations continues to advance the clinical translation timeline. ## Dihexa: Non-Human Primate Data Shows Measurable Synaptogenesis Dihexa, the synthetic hexapeptide derived from angiotensin IV, reached a significant preclinical milestone in 2026 with the publication of non-human primate data from the University of Toronto's Cognitive Neuroscience Lab. The study, published in Neuropsychopharmacology, reported that dihexa administration at 5 mg/kg produced measurable increases in dendritic spine density within 14 days — confirming in primates the synaptogenic effects previously observed only in rodent models. Research from multiple institutions has now documented synaptogenesis amplification rates seven times greater than brain-derived neurotrophic factor (BDNF) alone. Dihexa's mechanism — binding hepatocyte growth factor (HGF) receptors and activating the c-Met/PI3K/AKT signaling cascade — remains mechanistically distinct from all other cognitive peptides. However, the involvement of the HGF/c-Met pathway in tumor biology continues to raise theoretical oncogenic safety concerns that have slowed clinical translation. Despite its removal from FDA Category 2 in April 2026, no FDA-approved human clinical trials are actively recruiting for dihexa. ## Pentosan Polysulfate: 6-Month Canine OA Data Supports Disease-Modification Potential A 2026 study published in PLOS One provided the most compelling translational evidence yet for pentosan polysulfate sodium (PPS) as a disease-modifying osteoarthritis therapy. Researchers evaluated a six-week PPS injection course in companion dogs with naturally occurring osteoarthritis, tracking outcomes to 26 weeks (six months). PPS treatment delivered sustained clinical, functional, and structural benefits with no adverse events reported throughout the study period. Key biomarker findings included reductions in serum CTX-I (a bone resorption marker) and declining hyaluronic acid levels consistent with reduced inflammatory joint activity. A separate 21-year pharmacovigilance analysis of the FAERS database, published in Frontiers in Medicine, provided updated post-marketing safety context — confirming the retinal pigmentary maculopathy signal associated with chronic oral Elmiron use while distinguishing it from the different risk profile of short-course subcutaneous injection protocols used for joint health. The Phase 2/3 MaRVeL trial continues to evaluate PPS in human knee osteoarthritis patients with concurrent dyslipidaemia, with results expected to inform whether PPS can earn a formal DMOAD (disease-modifying osteoarthritis drug) designation. ## DSIP Fusion Peptides and the Blood-Brain Barrier Challenge Delta Sleep-Inducing Peptide (DSIP) research received a notable boost from a 2024 study published in Frontiers in Pharmacology that addressed one of DSIP's fundamental challenges: reliable delivery across the blood-brain barrier. Researchers demonstrated that DSIP fused with BBB-crossing peptides (DSIP-CBBBP), produced using Pichia pastoris expression systems, enhanced both sleep-promoting and neurotransmitter-balancing effects in PCPA-induced insomnia mouse models. This fusion peptide strategy represents a significant methodological advance over native DSIP administration. Additionally, intranasal DSIP administration showed neuroprotective potential in stroke models, with treated rats recovering motor function significantly faster on rotarod tests over an 8-day treatment course. With DSIP now removed from FDA Category 2 and scheduled for PCAC review, the regulatory landscape is shifting — though the core evidence base remains largely preclinical, and the original 1987 double-blind human insomnia trial found only modest sleep improvements. Modern delivery innovations like the fusion peptide approach may eventually overcome the translational barriers that have kept DSIP in preclinical limbo for decades. ## Regulatory Calendar and Pipeline Watch The PCAC meetings on July 23–24, 2026 at FDA White Oak Campus will address the compounding eligibility of the 12 peptides removed from Category 2. Public comments via docket FDA-2025-N-6895 are due by July 22, 2026. Retatrutide TRIUMPH-1 and TRIUMPH-2 Phase 3 readouts are expected Q2–Q3 2026, with Eli Lilly planning NDA filing in Q4 2026. The FDA is expected to render a decision on CagriSema (Novo Nordisk) by approximately October 2026. VK2735 VANQUISH-2 (subcutaneous) Phase 3 results are expected Q3 2026. A second round of PCAC meetings for remaining peptides is expected before February 2027. Ready to track your peptide research? [Open PepTracker Pro](https://app.peptrackerpro.com) PepTracker Pro Research Team The PepTracker Pro Research Team is an editorial group of science writers, pharmacologists, and clinical researchers dedicated to making peptide science accessible. Every article is reviewed for accuracy against peer-reviewed sources and updated as new evidence emerges. ## Citations 1. \[1\] FDA Announces Change in Status of 12 Peptides — SSRP Institute [Source](https://ssrpinstitute.org/news/fda-announces-change-in-status-of-12-peptides/) 2. \[2\] FDA To Review Whether To Allow More Access To Certain Peptides — U.S. News & World Report, April 17, 2026 [Source](https://www.usnews.com/news/health-news/articles/2026-04-17/fda-to-review-whether-to-allow-more-access-to-certain-peptides) 3. \[3\] Amid wellness craze, FDA weighs lifting peptide restrictions — Washington Post, April 15, 2026 [Source](https://www.washingtonpost.com/health/2026/04/15/peptides-fda-compounding/) 4. \[4\] Barman S. et al. — Exploring the antimicrobial potential of LL-37 derivatives. ACS Biomater Sci Eng. 2025 [Source](https://pubs.acs.org/doi/10.1021/acsbiomaterials.4c02029) 5. \[5\] Sánchez-Romero S. et al. — LL-37 is potent against non-growing E. coli. mSphere. 2024 [Source](https://journals.asm.org/doi/10.1128/msphere.00211-24) 6. \[6\] Wang J. et al. — Dihexa rescues cognitive impairment in APP/PS1 mice via PI3K/AKT. Int J Mol Sci. 2021 [Source](https://pmc.ncbi.nlm.nih.gov/articles/PMC8615599/) 7. \[7\] Martinez B. et al. — Effects of PPS on joint structure and function in canine OA out to six months. PLOS One. 2026 [Source](https://pmc.ncbi.nlm.nih.gov/articles/PMC12890089/) 8. \[8\] FAERS Pharmacovigilance — Post-marketing safety of PPS: 21-year analysis. Front Med. 2026 [Source](https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2026.1811896/full) 9. \[9\] Zhang L. et al. — Pichia pastoris secreted DSIP fusion peptide efficacy in insomnia models. Front Pharmacol. 2024 [Source](https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2024.1439536/full) 10. \[10\] FDA peptide advisers expected to support broader access push — STAT News, April 15, 2026 [Source](https://www.statnews.com/2026/04/15/peptides-fda-panel-to-discuss-broader-access-compounding/) **Disclaimer:** This article is for educational purposes only and does not constitute medical advice. Always consult a licensed healthcare provider. 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