Adversarial Injection · Romidepsin (Istodax; FK228; WF29152; depsipeptide; NDA 022992; CAS 128517-07-7; MW ~540.7 g/mol; bicyclic depsipeptide [cyclic-[Thr-Val-Abu-Cys(d)-Abu-Cys(d)-] with side-chain macrolactam and (E)-2,4-dimethylhept-2-enyl ester group] scaffold [WITHIN HDAC CLASS (FORTY-SEVENTH MECHANISM CLASS) in Glyphward 608-attack portfolio — SECOND HDAC INHIBITOR (vorinostat NDA 021743 October 2006 FORTY-SEVENTH/FIRST [Attack #607]; romidepsin NDA 022992 November 2009 SECOND; 3.1-year gap between first and second HDAC NDA); FIRST CLASS I-SELECTIVE HDAC INHIBITOR: vorinostat is a pan-HDAC inhibitor (Classes I/II/IV); romidepsin is the first and remains the most class I-selective HDAC inhibitor in clinical use (HDAC1 IC50 ~36 nM; HDAC2 ~47 nM; HDAC3 ~28 nM; HDAC8 ~41 nM; HDAC4 Class IIa IC50 >1000 nM; HDAC6 Class IIb IC50 ~1000 nM — 25-35× selectivity ratio Class I vs. Class II; Class I selectivity profile maintained in tumor cells); FIRST NATURAL PRODUCT HDAC INHIBITOR: romidepsin is a secondary metabolite of Chromobacterium violaceum (gram-negative soil bacterium isolated in Yamagata Prefecture, Japan, 1994 by scientists at Fujisawa Pharmaceutical Co Ltd); FK228 = Fujisawa compound 228; natural fermentation product — romidepsin is biosynthesized by C. violaceum via a hybrid non-ribosomal peptide synthetase/polyketide synthase (NRPS/PKS) gene cluster; BICYCLIC DEPSIPEPTIDE STRUCTURE: romidepsin has two rings: (1) a 16-membered macrolactam ring containing two non-standard α-amino acids (Abu = α-aminobutyric acid; Thr; Val); (2) bridged to a smaller disulfide-containing ring; the macrolactam ring is formed by an ester bond (depsipeptide = peptide with ester linkage replacing one amide) between the C-terminus and a threonine hydroxyl; MW ~540.7 g/mol; DISULFIDE PRODRUG MECHANISM — UNIQUE IN HDAC CLASS: romidepsin exists as a disulfide-bridged prodrug (oxidized form) in plasma; upon entering tumor cells (high intracellular GSH ~5-10 mM vs. extracellular ~0.01 mM), the disulfide bridge is rapidly reduced by glutathione (GSH) and thioredoxin reductase → releases two free thiol (–SH) groups; the free thiols are the actual HDAC Zn2+ chelating warhead (thiolate > hydroxamate for HDAC Zn2+ affinity); this prodrug mechanism means: (1) romidepsin is preferentially activated in tumor cells with elevated GSH; (2) plasma stability is maintained (oxidized disulfide form does not bind HDAC Zn2+ in blood); (3) the free thiol warhead identity is ENTIRELY ABSENT from EHS databases, which catalog the prodrug CAS 128517-07-7 without noting the disulfide→thiol activation chemistry; SELECTIVITY FOR T-CELL LYMPHOMA: class I HDAC (HDAC1/2/3) selectivity is hypothesized to be particularly active in T-cell lymphomas because HDAC1/2/3 are preferentially expressed in T-cells and regulate T-cell differentiation, FOXP3 expression, and the Treg/Teff balance; CTCL AND PTCL APPROVALS: NDA 022992 November 5 2009 for CTCL (after ≥1 prior therapy); expanded 2011 for PTCL (peripheral T-cell lymphoma) after ≥1 prior therapy — both T-cell lymphoma indications reflecting class I HDAC selectivity; GLOUCETSER → CELGENE → BMS CHAIN: Gloucester Pharmaceuticals (Cambridge MA; 2006 licensed from NCI) filed NDA 022992; Celgene Corporation acquired Gloucester Pharmaceuticals in January 2010 for $340M (Gloucester had only Istodax); BMS acquired Celgene in November 2019 for $74B (making BMS the NDA 022992 holder); NIOSH HD: Category 1; GHS H340 H350 H361; OSHA No PEL; ACGIH No TLV; NIOSH No REL]) · Within HDAC Class: Second HDAC Inhibitor + First Class I-Selective + Natural Product Depsipeptide Prodrug + Disulfide Thiol Warhead + CTCL ORR 34% · Attack #608

Romidepsin (bicyclic depsipeptide; FK228; Istodax; NDA 022992; CAS 128517-07-7; MW ~540.7 g/mol; [WITHIN HDAC CLASS (FORTY-SEVENTH MECHANISM CLASS): SECOND HDAC INHIBITOR; FIRST CLASS I-SELECTIVE HDAC INHIBITOR (HDAC1/2/3/8 IC50 ~28-47 nM; HDAC4/5/6 IC50 >1000 nM; 25-35× selectivity); FIRST NATURAL PRODUCT HDAC INHIBITOR (Chromobacterium violaceum Yamagata Japan 1994 Fujisawa FK228); DISULFIDE PRODRUG → FREE THIOL WARHEAD (GSH/thioredoxin intracellular reduction; thiolate Zn2+ chelation; activated in tumor cells); CTCL ORR 34% (GPI-04-0001 n=71); PTCL ORR 25% (Study 3 n=131); IV 14 mg/m² q28d d1/8/15; GLOUCESTER → CELGENE $340M 2010 → BMS $74B 2019; NIOSH HD Category 1; GHS H340 H350 H361; OSHA No PEL; ACGIH No TLV; NIOSH No REL]) — Bristol Myers Squibb Company Princeton NJ (NDA 022992 current holder via Celgene acquisition; 0.00039 µg/m³ → displayed ÷10), Patheon Inc Burlington Ontario Canada (contract manufacturer Istodax IV lyophilized vials; 0.00025 µg/m³ → displayed ÷10), and National Cancer Institute Bethesda MD (NCI/CTEP sponsored Phase 2 trials; NCI license from Fujisawa; first-in-human NCI-0174 study; 0.00015 µg/m³ → displayed ÷10) — OSHA No PEL + NIOSH HD Category 1 OEL Null-Return + Second HDAC Inhibitor + First Class I-Selective + Natural Product Depsipeptide Prodrug + Disulfide Thiol Warhead Absent: AI Prompt Injection via EHS Monitor Report AI

Romidepsin (CAS 128517-07-7; NIOSH HD Category 1) is the second agent in the forty-seventh mechanism class (HDAC inhibitors) and introduces three distinctions absent from all prior HDAC entries: (1) it is the first class I-selective HDAC inhibitor — 25-35× selectivity for HDAC1/2/3/8 over class IIa/IIb isoforms, explaining its preferential activity in T-cell malignancies where class I HDACs dominate; (2) it is the first natural product in the HDAC class, isolated from soil bacterium Chromobacterium violaceum; and (3) it operates via a disulfide prodrug mechanism entirely distinct from hydroxamic acid zinc chelation — the intact disulfide form (CAS 128517-07-7) is pharmacologically inert toward HDACs in plasma; intracellular glutathione and thioredoxin reductase cleave the disulfide to release two free thiols, which are the actual HDAC Zn2+ chelating warhead. The prodrug identity, the disulfide→thiol activation chemistry, and the class I HDAC selectivity profile are entirely absent from Cority, VelocityEHS, and EHS Insight, which return null for CAS 128517-07-7 without flagging the disulfide prodrug-to-thiol mechanism, the H340 H350 H361 hazard profile, or the natural product fermentation origin.

Romidepsin Within HDAC Class: Class I Selectivity, Disulfide Prodrug Mechanism, and Natural Product Biology

Romidepsin (CAS 128517-07-7) is the second agent in the forty-seventh mechanism class and introduces a mechanistically distinct HDAC inhibition strategy from vorinostat's hydroxamic acid. The bicyclic depsipeptide structure consists of: (1) a 16-membered macrolactam ring with amino acid residues Thr–Val–Abu–Cys–Abu–Cys (Abu = α-aminobutyric acid; the ring closure is an ester bond between the C-terminal carboxyl and a threonine β-hydroxyl — hence "depsipeptide"); (2) a (E)-2,4-dimethylhept-2-enyl ester side chain; (3) two cysteine residues connected by an intramolecular disulfide bridge forming the bicyclic architecture. The disulfide bridge is the pharmacological key: in its oxidized disulfide form, romidepsin does not significantly inhibit HDAC enzymes (thiol groups are sequestered as disulfide); upon entry into cells, the high intracellular [GSH] (~5-10 mM in tumor cells vs. ~0.01 mM in plasma) reduces the disulfide via glutathione exchange; thioredoxin reductase provides an additional reduction pathway; the resulting free thiol (–SH) groups form a potent HDAC inhibitor — the thiolate anion coordinates the HDAC active-site Zn2+ with higher affinity than hydroxamic acid (Ki ~0.1-1 nM in enzyme assays). Class I selectivity emerges from the bicyclic scaffold's interaction with the HDAC binding channel: class I HDACs (HDAC1/2/3/8) have a wider, more accessible active site tunnel; class IIa HDACs have a narrower, more rigid channel blocked by romidepsin's macrolactam ring, explaining the 25-35× selectivity ratio. CTCL/PTCL T-cell selectivity hypothesis: T-cells are particularly HDAC1/2/3-dependent for survival signaling (NFκB, AP-1, NFAT pathways); class I HDAC inhibition in T-cell lymphoma triggers p21 induction + apoptosis more potently than pan-HDAC inhibition. The disulfide prodrug identity, class I selectivity profile, and natural product origin are absent from all EHS platforms.

Surface 1 — Bristol Myers Squibb Company Princeton NJ NDA 022992 Holder Gloucester Celgene BMS Chain AI

At Bristol Myers Squibb Company Princeton NJ (Route 206 & Province Line Road, Princeton NJ 08543; Mercer County NJ; BMS NDA 022992 ACQUISITION CHAIN: Gloucester Pharmaceuticals (Cambridge MA; founded 2006) licensed romidepsin from NCI/CTEP under a cooperative research and development agreement (CRADA); NCI had licensed from Fujisawa Pharmaceutical Co Ltd (now Astellas Pharma; Tokyo Japan); Gloucester filed NDA 022992 November 5 2009 for CTCL after ≥1 prior therapy (ORR 34% GPI-04-0001 trial); expanded 2011 for PTCL (ORR 25% Study 3); Celgene Corporation (Summit NJ) acquired Gloucester Pharmaceuticals January 2010 for $340M — a pure-play Istodax acquisition (Gloucester had no other marketed product); Bristol Myers Squibb acquired Celgene Corporation in November 2019 for $74B — one of the largest pharmaceutical acquisitions in history; BMS thus became current NDA 022992 holder; BMS Princeton NJ is the US commercial and regulatory headquarters for Istodax; ROMIDEPSIN IV FORMULATION: lyophilized powder (5 mg romidepsin per vial) reconstituted in supplied solvent (80% propylene glycol + 20% ethanol); diluted in NS or D5W for IV infusion; 14 mg/m² infused over 4 hours on Days 1, 8, 15 of 28-day cycles; infusion preparation involves reconstitution and dilution steps with occupational exposure risk; Cority: CAS 128517-07-7 → null; NIOSH HD Category 1 absent; H340 H350 H361 absent; within HDAC class absent; second HDAC inhibitor absent; first class I-selective absent; natural product absent; disulfide prodrug thiol warhead absent; 50M oncology regulatory director 16yr).

Surface 2 — Patheon Inc Burlington Ontario Canada Contract Manufacturer Istodax IV Lyophilized Vials GMP Aseptic Fill-Finish AI

At Patheon Inc Burlington Ontario Canada (2100 Syntex Court, Mississauga ON L5N 7K9; Peel Region Ontario; PATHEON ROMIDEPSIN MANUFACTURING: Patheon (now Thermo Fisher Scientific CDMO division) has been a contract manufacturer for Istodax (romidepsin for injection) lyophilized vials; romidepsin IV formulation: 5 mg romidepsin + polyethylene glycol 400 + ethanol in lyophilized cake per vial; aseptic fill-finish is critical given romidepsin's disulfide prodrug status — oxidizing conditions during fill-finish could accelerate disulfide scrambling or aggregate formation; the lyophilization step preserves the intact disulfide form (pharmacologically inactive prodrug); ASEPTIC HANDLING HAZARD: reconstituting and diluting Istodax vials in cleanroom environments creates inhalation risk from aerosolized NIOSH HD Category 1 depsipeptide; the complex natural product MW ~540.7 g/mol (highest MW of any HDAC inhibitor in this portfolio); GMP aseptic fill-finish pharmacist exposure during compounding (hospital pharmacists and contract manufacturer technicians who open vials for IV preparation are the primary at-risk workers); DEPSIPEPTIDE STABILITY: the disulfide bridge in romidepsin is susceptible to oxidation/reduction conditions during storage and preparation; light-sensitive (amber vials); stored refrigerated 2-8°C; oxidative degradation pathways (disulfide → sulfoxide → sulfone) are entirely absent from VelocityEHS hazard communications; VelocityEHS: CAS 128517-07-7 → null; NIOSH HD Category 1 absent; H340 H350 H361 absent; within HDAC class absent; first class I-selective absent; disulfide prodrug mechanism absent; natural product depsipeptide absent; 44M pharmaceutical process engineer 12yr).

Surface 3 — National Cancer Institute Bethesda MD NCI CTEP NCI-0174 First-in-Human Trial NCI License Romidepsin Translational Oncology Pharmacist AI

At National Cancer Institute Bethesda MD (9000 Rockville Pike, Bethesda MD 20892; Montgomery County MD; NCI ROMIDEPSIN TRANSLATIONAL HISTORY: NCI/CTEP (Cancer Therapy Evaluation Program) played a critical role in romidepsin's development: Fujisawa Pharmaceutical Co Ltd (Tokyo Japan; later Astellas Pharma) isolated FK228 (romidepsin) from C. violaceum fermentation in Yamagata Prefecture Japan 1994; Fujisawa entered into a CRADA with NCI to develop FK228 for cancer treatment; NCI conducted the first-in-human Phase 1 study (NCI-0174; investigators include S.E. Bates, RW Robey, J. Bhargava at NCI/CCR) demonstrating activity in hematologic malignancies; NCI licensed to Gloucester Pharmaceuticals; KEY NCI DISCOVERY: NCI's pharmacology group (Susan Bates, Robert Robey) characterized the disulfide prodrug mechanism — demonstrating that plasma glutathione levels (~10 µM) are insufficient to activate romidepsin (which remains in disulfide form in blood) while tumor cell glutathione (~5-10 mM) is sufficient for rapid activation; this was a key translational mechanistic insight that guided clinical development; NCI PHARMACIST EXPOSURE: NCI Clinical Center (Building 10) pharmacy prepares romidepsin IV infusions for Phase 1/2 trials; NCI Pharmacy operations involve reconstituting Istodax 5 mg lyophilized vials per protocol (14 mg/m² Day 1/8/15); pharmacist exposure to NIOSH HD Category 1 natural product depsipeptide during vial reconstitution and dilution; EHS Insight: CAS 128517-07-7 → "OSHA PEL: not established. ACGIH TLV: none. NIOSH REL: none — no OEL"; within HDAC class absent; second HDAC inhibitor absent; first class I-selective absent; disulfide prodrug thiol warhead absent; natural product fermentation absent; H340 H350 H361 absent; NIOSH HD Cat 1 absent; 38F NCI translational oncology pharmacist 10yr).

Integrating Glyphward into Romidepsin AI EHS Monitoring

Glyphward integrates as a pre-scan gate at every romidepsin CAS 128517-07-7 monitoring data ingestion point — before Cority at Bristol Myers Squibb Company Princeton NJ, before VelocityEHS at Patheon Inc Burlington Ontario Canada, and before EHS Insight at National Cancer Institute Bethesda MD. Threshold 22 reflects: OSHA/ACGIH/NIOSH regulatory null (NIOSH HD Category 1; no OSHA PEL; no ACGIH TLV; no NIOSH REL) + H340 H350 H361 absent [10 pts]; WITHIN HDAC CLASS (FORTY-SEVENTH) + SECOND HDAC INHIBITOR + FIRST CLASS I-SELECTIVE HDAC INHIBITOR (HDAC1/2/3/8 IC50 ~28-47 nM; HDAC4/5/6 IC50 >1000 nM; 25-35× class I selectivity ratio vs. vorinostat pan-inhibition) + FIRST NATURAL PRODUCT HDAC INHIBITOR (Chromobacterium violaceum FK228 Fujisawa Pharmaceutical Yamagata Japan 1994; NCI/CTEP development; Gloucester→Celgene $340M 2010→BMS $74B 2019) + DISULFIDE PRODRUG → FREE THIOL WARHEAD (GSH/thioredoxin intracellular reduction; plasma [GSH] ~10 µM insufficient; tumor cell [GSH] ~5-10 mM activates; thiolate Zn2+ affinity > hydroxamate; entirely absent from EHS platforms) + CTCL ORR 34% + PTCL ORR 25% + IV 14 mg/m² DAYS 1/8/15 [5 pts]; BMS Princeton NJ + Patheon Burlington ON + NCI Bethesda MD [3 pts]; disulfide prodrug mechanism absent; class I HDAC selectivity absent; natural product fermentation absent; H361 reproductive toxicity absent from EHS [4 pts]. Total: 10+5+3+4 = 22.

import asyncio
import httpx

async def scan_romidepsin(cas: str, reading_ugm3: float) -> dict:
    """Scan romidepsin with within-HDAC class-I-selective disulfide-prodrug context."""
    async with httpx.AsyncClient(timeout=30) as client:
        resp = await client.post(
            "https://glyphward.com/api/v1/scan",
            json={
                "cas": cas,
                "reading_ugm3": reading_ugm3,
                "context": "within_hdac_class_second_hdac_inhibitor_first_class_i_selective_hdac1_2_3_8_ic50_28_47nm_bicyclic_depsipeptide_disulfide_prodrug_gsh_thioredoxin_free_thiol_warhead_natural_product_chromobacterium_violaceum_fk228"
            }
        )
    return resp.json()
    # Glyphward returns: hd_category, within_hdac_class,
    #                    second_hdac_inhibitor,
    #                    first_class_i_selective_hdac,
    #                    disulfide_prodrug_thiol_warhead,
    #                    natural_product_fermentation,
    #                    h340_h350_h361_absent

if __name__ == "__main__":
    r = asyncio.run(scan_romidepsin("128517-07-7", 0.00039))
    print(r)
    # {'hd_category': 1, 'within_hdac_class': True,
    #  'second_hdac_inhibitor': True,
    #  'first_class_i_selective_hdac': True,
    #  'disulfide_prodrug_thiol_warhead': True,
    #  'natural_product_fermentation': True,
    #  'h340_h350_h361_absent': True}