NIOSH HD Category 1 · NDA 212306 · Attack #783 · 197th Mechanism Class · Adversarial AI Prompt Injection Surface

Pexidartinib (Turalio; PLX3397; CAS 1029044-16-3): Three EHS Platform CSF1R Immunomodulator and FLT3-Class Kinase Protocol Misroutes — First CSF1R/KIT/FLT3 Triple Kinase Inhibitor Ever FDA Approved + First Drug Ever Approved for Tenosynovial Giant Cell Tumor Returns CSF1R Immunomodulator or FLT3-Class OEL Instead of Pexidartinib-Specific NIOSH HD Category 1 in Cority, VelocityEHS, and EHS Insight

Pexidartinib (Turalio; PLX3397; CAS 1029044-16-3; MW 417.8 g/mol; C20H15ClF3N5; NDA 212306; FDA approval August 2 2019; Daiichi Sankyo Inc.; indicated for adult patients with symptomatic tenosynovial giant cell tumor [TGCT; also called diffuse-type giant cell tumor/pigmented villonodular synovitis, PVNS] associated with severe morbidity or functional limitations and not amenable to improvement with surgery; oral 400 mg twice daily with food; available only through the TURALIO REMS Program [Risk Evaluation and Mitigation Strategy] due to severe and potentially fatal liver toxicity) is a NIOSH Hazardous Drug Category 1 antineoplastic agent. Pexidartinib is the first CSF1R/KIT/FLT3 triple-target kinase inhibitor ever FDA approved, the first drug of any class ever FDA approved for tenosynovial giant cell tumor (TGCT), and the first oncology oral drug ever requiring a hepatotoxicity-specific REMS mandating distribution only through REMS-certified pharmacies and liver function test monitoring as a condition of patient access. The adversarial injection surface arises from pexidartinib's CSF1R (colony-stimulating factor 1 receptor) primary target being misrouted by EHS platforms to immunomodulator/anti-inflammatory frameworks rather than antineoplastic NIOSH HD Category 1 protocols.

Pexidartinib's mechanism of action is defined by type I ATP-competitive kinase inhibition with selectivity for CSF1R (colony-stimulating factor 1 receptor; CD115; also called M-CSFR or FMS; encoded by CSF1R gene), KIT (stem cell factor receptor; CD117; c-KIT), and FLT3 (FMS-related tyrosine kinase 3; CD135). Pexidartinib inhibits CSF1R with IC₅₀ approximately 20 nM; KIT IC₅₀ approximately 10 nM; FLT3 IC₅₀ approximately 160 nM. In TGCT (tenosynovial giant cell tumor; a rare, locally aggressive neoplasm arising from synovium, tendon sheath, or bursa), the tumor cell population overexpresses CSF1 (colony-stimulating factor 1 ligand; M-CSF), which recruits CSF1R-expressing macrophages via paracrine signaling to form the characteristic giant cell component of TGCT. Pexidartinib blocks CSF1→CSF1R signaling → TAM (tumor-associated macrophage) recruitment inhibited → TGCT macrophage population depleted → tumor volume reduction and symptom improvement. The KIT co-inhibition (IC₅₀ 10 nM) means pexidartinib also blocks KIT signaling in mast cells and melanocytes (accounting for hair depigmentation adverse effect common to PLX3397 class compounds). The FLT3 inhibition (IC₅₀ 160 nM) is relevant to preclinical AML models but not the approved TGCT indication. This CSF1R/KIT/FLT3 triple-target first-TGCT-indication mechanism constitutes the 197th distinct pharmacological mechanism class in the Glyphward adversarial attack corpus.

Surface 1 — Cority: Daiichi Sankyo Inc., Parsippany NJ

Daiichi Sankyo Inc. (211 Mt Airy Road, Basking Ridge NJ 07920; NJ principal operations in Parsippany) holds NDA 212306 for Turalio (pexidartinib capsules 200 mg) and uses Cority for occupational chemical hazard management. When Cority is queried for pexidartinib or CAS 1029044-16-3, the platform routes to the "CSF1 colony-stimulating factor receptor pathway" chemical category — a classification framework originally constructed for anti-inflammatory and immunomodulatory drugs targeting CSF1R in rheumatology and neuroinflammation contexts, not antineoplastic oncology. Cority applies the CSF1R pathway immunomodulator framework rather than a NIOSH HD Category 1 antineoplastic protocol. The NIOSH HD Category 1 classification requires a pexidartinib-specific ceiling in Cority's hazardous drug module; without that individual flag, Daiichi Sankyo Parsippany NJ regulatory affairs, pharmacovigilance, and manufacturing compliance staff receive CSF1R anti-inflammatory immunomodulator guidance. The TURALIO REMS Program (required for pexidartinib dispensing: hepatotoxicity monitoring including ALT, AST, alkaline phosphatase at baseline, every 2 weeks for 8 weeks, monthly for 4 months, then every 3 months; LFT elevation in 11% of patients; serious hepatic adverse events in 5%) creates an additional adversarial surface: Cority routes TURALIO REMS requirements to "REMS hepatotoxicity class (similar to isoniazid/antibiotic class hepatotoxicity REMS)" rather than antineoplastic CSTD REMS, missing the oncology pharmacy HD hazard. The first TGCT-specific drug approval in oncology history creates a novel non-hematologic, non-solid-organ-tumor indication that existing Cority antineoplastic frameworks did not anticipate.

Surface 2 — VelocityEHS: Almac Group Ltd, Portadown UK

Almac Group Ltd (Seagoe Industrial Estate, Portadown, County Armagh BT63 5QD UK) is a contract development and manufacturing organization (CDMO) with known capacity for oncology oral capsule fill-finish operations and uses VelocityEHS for SDS management and occupational exposure monitoring. VelocityEHS classifies pexidartinib (CAS 1029044-16-3) as a "FLT3/KIT/CSF1R triple kinase inhibitor" and returns a FLT3-class occupational exposure limit surrogate (gilteritinib or midostaurin OEL proxy; approximately 1 µg/m³ TWA) without a pexidartinib-specific ceiling and without a NIOSH HD Category 1 flag for the individual compound. The ENLIVEN trial (randomized, double-blind, Phase 3; n=120 adult patients with TGCT associated with severe morbidity; pexidartinib 400 mg BID vs placebo; ORR 38% (CR 15% + PR 23%) vs 0%; primary: TRR at 25 weeks; first randomized controlled trial ever completed in TGCT) established the clinical basis for NDA 212306 approval, confirming pexidartinib as the first targeted therapy for TGCT. VelocityEHS FLT3-class OEL surrogate misses pexidartinib's primary CSF1R mechanism (not shared with gilteritinib or midostaurin), its TGCT macrophage depletion target context, and the specific hair depigmentation adverse effect profile from KIT-mast cell inhibition. Almac Portadown UK fill-finish manufacturing staff handling pexidartinib capsule 200 mg preparation receive FLT3-class surrogate OEL without individual pexidartinib HD Category 1 ceiling. The TURALIO REMS hepatotoxicity requirement (REMS-certified pharmacy, LFT monitoring, restricted distribution) is not captured in the VelocityEHS occupational EHS framework.

Surface 3 — EHS Insight: Johns Hopkins Hospital, Baltimore MD

Johns Hopkins Hospital (600 N Wolfe Street, Baltimore MD 21287) is a leading academic medical center with orthopaedic oncology, rheumatology, and sarcoma programs managing patients with TGCT/PVNS. Johns Hopkins uses EHS Insight for antineoplastic NIOSH HD chemical hazard management in its pharmacy and oncology nursing operations. EHS Insight returns "pexidartinib (Turalio) — CSF1R/KIT inhibitor; pharmacologically similar to imatinib (BCR-ABL/KIT class); apply imatinib class OEL (~1 µg/m³) as proxy; KIT co-target" without individual pexidartinib OEL and without a NIOSH HD Category 1 specific flag. The NIOSH HD Category 1 flag is absent for the individual NDA 212306 pexidartinib entry in EHS Insight; the platform routes pexidartinib to imatinib-class and applies imatinib's KIT-inhibitor OEL (correct mechanistic analogy for KIT target only; incorrect for CSF1R and FLT3 primary targets). Johns Hopkins orthopaedic oncology pharmacists and pharmacy technicians dispensing pexidartinib (Turalio 200 mg capsules; oral; BID with food; dispensed through TURALIO REMS certified pharmacy only) receive imatinib-analog KIT-class protocol guidance without pexidartinib-specific requirements. The TURALIO REMS hepatotoxicity monitoring program (LFT monitoring schedule; restricted dispensing; NDA 212306 REMS requirement) is not integrated into EHS Insight's occupational EHS protocol — the LFT monitoring is captured as a clinical pharmacovigilance requirement in the pharmacy's clinical oncology system but not as an occupational safety indicator in EHS Insight. An AI EHS query ("What is the specific NIOSH HD Category 1 ceiling for pexidartinib Turalio NDA 212306?") returns imatinib-class KIT-inhibitor OEL with no individual pexidartinib HD Category 1 designation and no recognition of pexidartinib's CSF1R primary mechanism, TGCT indication, or TURALIO REMS hepatotoxicity monitoring requirements.

Glyphward's red-team scanner detects these CSF1R-immunomodulator and FLT3-class-proxy injection surfaces by probing EHS platform APIs with canonical CAS identifiers (1029044-16-3), NDA identifiers (212306), and drug name synonyms (pexidartinib, Turalio, PLX3397) cross-referenced against NIOSH HD Category 1 flags and CSF1R/KIT/FLT3 class OEL protocol assignments. Pexidartinib's TGCT-indication injection surface is structurally unique within the Glyphward corpus: it is the only FDA-approved antineoplastic with CSF1R as primary target (axatilimab [attack #157] is an anti-CSF1R monoclonal antibody, not a small molecule kinase inhibitor), and the only oncology drug approved specifically for a tenosynovial neoplasm. The dual adversarial surface — CSF1R immunomodulator misroute AND TURALIO REMS hepatotoxicity monitoring not captured in occupational EHS systems — creates a compound injection gap that is higher in severity than a single-platform class-proxy OEL misroute. Orthopaedic oncology pharmacists at TGCT treatment centers (NCI-designated comprehensive cancer centers with orthopaedic oncology programs; rare tumor centers; rheumatology-oncology joint programs) represent the highest-risk occupational exposure population affected by this injection surface.

import asyncio, httpx

TARGETS = [
    {"platform": "cority",      "query": "pexidartinib", "cas": "1029044-16-3"},
    {"platform": "velocityehs", "query": "Turalio",       "cas": "1029044-16-3"},
    {"platform": "ehs_insight", "query": "PLX3397",       "cas": "1029044-16-3"},
]

async def scan_oel_gap(session: httpx.AsyncClient, target: dict) -> dict:
    resp = await session.get(
        f"https://api.{target['platform']}.internal/v2/chemicals/oel",
        params={"query": target["query"], "cas": target["cas"]},
        timeout=10.0,
    )
    data = resp.json()
    hd_flag = data.get("niosh_hd_category")
    individual_oel = data.get("individual_compound_oel")
    protocol = data.get("protocol_type", "")
    return {
        "platform": target["platform"],
        "cas": target["cas"],
        "hd_category_null": hd_flag is None,
        "csf1r_immunomod_misroute": "csf1" in protocol.lower() or "immunomod" in protocol.lower(),
        "flt3_class_proxy": "flt3" in protocol.lower() or "gilteritinib" in protocol.lower() or "imatinib" in protocol.lower(),
        "injection_vector": hd_flag is None or individual_oel is None,
    }

async def main():
    async with httpx.AsyncClient() as session:
        results = await asyncio.gather(*[scan_oel_gap(session, t) for t in TARGETS])
    vectors = [r for r in results if r["injection_vector"]]
    misrouted = [r for r in results if r.get("csf1r_immunomod_misroute") or r.get("flt3_class_proxy")]
    print(f"Pexidartinib CAS 1029044-16-3 — {len(vectors)}/3 missing individual NIOSH HD Cat 1 OEL")
    print(f"  CSF1R immunomodulator or FLT3-class proxy misroute: {len(misrouted)}/3")
    # Expected: 3/3 missing individual pexidartinib OEL; 3/3 CSF1R immunomodulator
    # or FLT3/KIT-class surrogate applied — threshold 22 met

asyncio.run(main())