The Next Tranche: Five More Peptides Headed to a Second FDA PCAC Review by February 2027

On April 15, 2026, the FDA announced the removal of 12 peptide bulk drug substances from Category 2 of its interim 503A list and scheduled two separate Pharmacy Compounding Advisory Committee (PCAC) meetings to evaluate them for the 503A bulk drug substances list. The first meeting is set for July 23-24, 2026 and covers seven peptides. A second meeting, which the agency has said will be held before the end of February 2027, will evaluate the remaining five. As of the last-verified date, the exact date of the second meeting had not been published.

According to FDA materials and regulatory commentary, the five peptides on the second-tranche agenda are GHK-Cu (injectable routes), Melanotan II, Cathelicidin (LL-37), Dihexa acetate, and Pegylated Mechano Growth Factor (PEG-MGF). These five span a more heterogeneous set of chemistries than the July candidates — a copper coordination complex, a melanocortin-receptor agonist, a host-defense peptide, an angiotensin-derived oligopeptide, and a PEGylated growth-factor fragment. The FDA has not published its reason for assigning these five to a separate session.

Section 503A of the Federal Food, Drug, and Cosmetic Act exempts certain compounded drugs from specific FDA requirements provided the bulk drug substance used meets one of three conditions: it complies with an applicable USP/NF monograph, it is a component of an FDA-approved drug, or it appears on the FDA's 503A bulks list. Peptides nominated for the list that fall outside the first two conditions must be evaluated through the PCAC, which reviews the available chemistry, manufacturing, and safety record and then recommends whether a substance should be added.

The FDA's interim list sorts nominated substances into three categories. Category 1 substances may be eligible for the bulks list and receive interim enforcement discretion. Category 2 substances were judged to raise significant safety concerns and are ineligible for enforcement discretion. Category 3 substances lack sufficient data for evaluation. The April 2026 action moved 12 peptides out of Category 2 — but, as the regulatory commentary stresses, that removal does not place them in Category 1 and does not authorize compounding. PCAC review is the mechanism through which a path to the bulks list is decided.

Unlike the July tranche — which is dominated by short synthetic peptides and peptide fragments — the second tranche groups together five structurally distinct molecules. The table below maps each compound to its class and structural identity as reported in the chemical literature. (This grouping by chemistry is ChemVerify's own characterization for analytical context; it is not a statement of the FDA's reason for the agenda split.)

These class differences are relevant to how each compound is characterized analytically. A copper-coordination complex such as GHK-Cu raises questions of metal stoichiometry and free-copper content that a pure synthetic peptide does not. A PEGylated species such as PEG-MGF introduces polymer-dispersity and conjugation-site considerations absent from an unmodified oligopeptide. A cyclic analog such as Melanotan II requires confirmation of the intramolecular ring, and a host-defense peptide such as LL-37 — at 37 residues — is substantially longer and more conformationally complex than the short fragments on the July list. These are analytical-characterization points, not statements about the substances' regulatory standing or any intended use.

The 12 peptides removed from Category 2 were not all scheduled for the same session, but the FDA has not published a rationale for which substances went to July versus to the February-2027 meeting. Regulatory commentary notes that GHK-Cu's injectable routes were handled on a separate track — secondary sources report this was tied to the nomination history for the injectable form rather than to a published scientific rationale. Beyond that, any account of why the agenda was divided is inference rather than an FDA-stated reason. ChemVerify's own observation is simply that the second-tranche compounds are chemically more heterogeneous; we present that as analytical context, not as the agency's reasoning.

One documented nuance specific to GHK-Cu is that the action grouped its injectable routes into this regulatory track. GHK-Cu also appears in topical contexts, which sit under a different regulatory posture; the PCAC track described here concerns its status as an injectable bulk drug substance for compounding. Researchers should confirm the precise scope against the Federal Register notice rather than relying on summaries.

Appearing on a PCAC agenda means a substance is being formally evaluated; it does not mean the substance has been added to the 503A bulks list, and it does not by itself change the substance's legal status. The committee issues a recommendation, after which the FDA decides whether to propose adding the substance to the bulks list through notice-and-comment rulemaking. The February-2027 convening is therefore a forward marker on the regulatory calendar, not an endpoint.

• Removal from Category 2 (April 2026) does not authorize compounding and does not confer Category 1 status.
• A PCAC recommendation is advisory; the FDA makes the final determination on bulks-list inclusion.
• The July 2026 docket (FDA-2025-N-6895) and the second-tranche review are evaluation steps, not approvals.
• All five second-tranche compounds are handled here strictly as research-use-only substances for the purposes of laboratory sourcing and verification.

According to FDA materials and regulatory commentary, the five peptides scheduled for the second PCAC convening before the end of February 2027 are GHK-Cu (injectable routes), Melanotan II, Cathelicidin (LL-37), Dihexa acetate, and Pegylated Mechano Growth Factor (PEG-MGF). They are distinct from the seven peptides on the July 23-24, 2026 agenda.

The FDA has said the second Pharmacy Compounding Advisory Committee meeting will be held before the end of February 2027. The exact date had not been published as of June 2026; the agency committed to convening it within that window. Researchers should check the FDA advisory-committee calendar for the confirmed date.

No. Removal from Category 2 in April 2026 did not authorize compounding and did not move the substances into Category 1. Each peptide still has to be evaluated by the PCAC, and the FDA then decides whether to propose adding it to the 503A bulks list. Until that process concludes, the regulatory status is unchanged by the Category 2 removal alone.

Based on the chemical literature, they span several distinct classes: GHK-Cu is a copper coordination complex of a tripeptide; Melanotan II is a cyclic melanocortin-receptor agonist analog of alpha-MSH; Cathelicidin (LL-37) is a 37-residue host-defense peptide; Dihexa acetate is an angiotensin IV-derived oligopeptide active at the HGF/c-Met system; and PEG-MGF is a PEGylated fragment of mechano growth factor, an IGF-1 splice variant. This is a structural description for analytical context only.

The FDA has not published a reason for splitting the agenda. Secondary sources report that GHK-Cu's injectable form was handled on a separate track tied to its nomination history. Beyond that, the division between July and February has no FDA-stated rationale; observations that the second-tranche compounds are chemically more heterogeneous are analytical context offered by commentators, not the agency's reasoning.

The docket number for the July 23-24, 2026 PCAC meeting is FDA-2025-N-6895. Comments received by July 9, 2026 were to be provided to the committee, and the docket closed on July 22, 2026.

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