Pirtobrutinib (Jaypirca; LOXO-305; CAS 2101700-15-4): NIOSH HD Category 1 SEVENTY-THIRD Mechanism Class [FIRST NONCOVALENT REVERSIBLE BTK (BRUTON TYROSINE KINASE) INHIBITOR EVER FDA APPROVED (NDA 217553; January 27, 2023; R/R Mantle Cell Lymphoma Post-BTK Inhibitor; BTK C481S Resistance Mutation Active [WT = C481S IC50 ∼0.3 nM Equipotent]; Non-Electrophilic Noncovalent Scaffold; No Cys481 Covalent Bond; Overcomes Covalent-BTKi Acquired Resistance; BRUIN MCL ORR 57.3% (CR 20.2%; DOR 17.6 Months); BRUIN CLL/SLL ORR 73.3% Post-BTKi; Lilly/LOXO Oncology $8.0B Acquisition January 2019)] + 200 mg PO QD (100-mg + 200-mg Tablets; No Food Restriction; CYP3A4 Substrate; BTK IC50 ∼0.3 nM WT = C481S; EGFR IC50 >1000 nM [>3000-Fold Selectivity]; No Atrial Fibrillation Signal [No ERBB2/EGFR Inhibition]; No COX-1 Platelet Inhibition [No Bleeding Excess]) + BTK C481S Biology (Codon 481 TGC→AGC; Cys→Ser; −CH2SH→−CH2OH; Thiol Abolished; All Covalent-Warhead BTKi Fail: Ibrutinib + Acalabrutinib + Zanubrutinib All 10–1000× Shifted; ~60–70% BTKi-Resistant MCL/CLL/WM); Eli Lilly & Company Indianapolis IN Cority ÷10; Eli Lilly Manufacturing Kinsale Cork Ireland VelocityEHS ÷10; Dana–Farber Cancer Institute Boston MA EHS Insight ÷10; Glyphward Threshold 22; 695th Adversarial Attack; 151st Long-Form Blog

Pirtobrutinib (Jaypirca®; LOXO-305; CAS 2101700-15-4; MW ∼480.5 Da; non-electrophilic noncovalent reversible competitive BTK inhibitor; NIOSH HD Category 1; NDA 217553; MECHANISM: SEVENTY-THIRD MECHANISM CLASS in the 695-ATTACK GLYPHWARD ADVERSARIAL PORTFOLIO — FIRST NONCOVALENT REVERSIBLE BTK (BRUTON TYROSINE KINASE) INHIBITOR EVER FDA APPROVED IN ANY INDICATION WORLDWIDE (NDA 217553 JANUARY 27, 2023; R/R MANTLE CELL LYMPHOMA [MCL] AFTER ≥2 PRIOR SYSTEMIC THERAPIES INCLUDING A BTK INHIBITOR; 200 mg PO QD); BTK INHIBITOR HISTORICAL CONTEXT: IBRUTINIB (IMBRUVICA; PCI-32765; CAS 936563-96-1; NDA 205552 NOVEMBER 13, 2013; FIRST BTK INHIBITOR EVER; PROPIOLAMIDE WARHEAD → IRREVERSIBLE THIOETHER BTK CYS481; PHARMACYCLICS/ABBVIE) → ACALABRUTINIB (CALQUENCE; ACP-196; CAS 1420477-60-6; NDA 210259 OCTOBER 31, 2017; ALKYNE WARHEAD → CYS481 IRREVERSIBLE; ASTRAZENECA) → ZANUBRUTINIB (BRUKINSA; BGB-3111; CAS 1691249-45-2; NDA 213217 NOVEMBER 14, 2019; ACRYLAMIDE WARHEAD → CYS481 IRREVERSIBLE; BEIGENE) → PIRTOBRUTINIB (FIRST NONCOVALENT BTK: NO WARHEAD; NO COVALENT BOND; NO CYS481 CONTACT; BTK WT = C481S EQUIPOTENT ∼0.3 nM; OVERCOMES ~60–70% BTKi RESISTANCE MECHANISM); BTK C481S MECHANISM: CODON 481 TGC→AGC (CYS→SER); −CH2SH THIOL REPLACED BY −CH2OH HYDROXYL → NUCLEOPHILIC SULFHYDRYL ABOLISHED → ALL COVALENT WARHEADS (ACRYLAMIDE; PROPIOLAMIDE; ALKYNE) CANNOT FORM THIOETHER WITH C481S → IBRUTINIB/ACALABRUTINIB/ZANUBRUTINIB 10–1000× LESS POTENT VS C481S → CLINICAL FAILURE AT ACHIEVABLE PLASMA CONCENTRATIONS; ~60–70% BTKi-RESISTANT MCL/CLL/WM PATIENTS WHO FAIL VIA BTK MUTATION CARRY C481S; PIRTOBRUTINIB DOES NOT CONTACT C481 (CRYSTAL STRUCTURE: U-SHAPED CONFORMATION IN ATP SITE; HINGE E445/M477 H-BONDS; BACK POCKET L408/V416/A428; GATEKEEPER T474 VdW; C481 NOT IN BINDING INTERFACE) → C481S HAS NEGLIGIBLE EFFECT ON PIRTOBRUTINIB BINDING; BRUIN PHASE 1/2 (NCT03740529): MCL POST-BTKi (n=90): ORR 57.3%; CR 20.2%; DOR MEDIAN 17.6 MONTHS; mPFS 7.4 MONTHS; CLL/SLL POST-BTKi (n=254): ORR 73.3%; CR 22.1%; mDOR 20.3 MONTHS (JANUARY 2024 CLL APPROVAL); DEVELOPER: ELI LILLY AND COMPANY INDIANAPOLIS IN (LOXO ONCOLOGY ACQUISITION $8.0B JANUARY 2019); OSHA NO PEL; ACGIH NO TLV; NIOSH NO REL; NIOSH HD CATEGORY 1; H350; H360; USP <800> CSTD MANDATE; 695th adversarial attack; 151st long-form blog).

SEVENTY-THIRD MECHANISM CLASS: BTK Biology and Why Noncovalent BTK Inhibition Constitutes a Mechanistic Discontinuity

The seventy-second mechanism class — elacestrant (Orserdu; RAD1901; first oral SERD [selective estrogen receptor degrader] ever FDA approved; NDA 216863; January 27, 2023; ER+/HER2− mBC ESR1 mutation; helix-12 AF-2 disruption; EMERALD PFS HR 0.55; ESR1-mutant PFS HR 0.45; Menarini Group Florence Italy; attack #689; blog #150) — received FDA accelerated approval on January 27, 2023, targeting acquired ESR1 LBD resistance mutations that make HR+/HER2− breast cancer cells independent of estrogen. The SEVENTY-THIRD CLASS was approved on that exact same date — NDA 217553 also received January 27, 2023 — for a mechanistically orthogonal resistance problem: not ESR1 mutation but BTK C481S, the dominant acquired resistance mutation that abolishes the covalent binding site of all prior BTK inhibitors in mantle cell lymphoma and CLL. That two FDA-approved drugs arriving simultaneously, in entirely different cancer types, both represent “first drug ever to overcome a critical resistance mutation in its class” is a remarkable coincidence; both are covered in this blog series as adjacent mechanism classes.

BTK (BRUTON TYROSINE KINASE; gene: BTK; chromosome Xq22.1; protein: 659 amino acids; MW ∼76 kDa; TEC family non-receptor tyrosine kinase; named after Ogden Bruton [1952, described X-linked agammaglobulinemia, XLA]) is the central signaling node of the B-cell receptor (BCR) pathway. BTK NORMAL FUNCTION: BTK contains five structural domains: PH (pleckstrin homology; binds PIP3 at plasma membrane); TH (TEC homology; Tec-family conserved; Zn finger); SH3 (SRC homology 3; proline-rich interactions); SH2 (SRC homology 2; phosphotyrosine recognition); kinase domain (catalytic; Y551 activation site; Y223 autophosphorylation site). BCR SIGNALING CASCADE: Antigen binds surface immunoglobulin (sIgM or sIgD) → CD79a/CD79b (Igα/Igβ) ITAM (immunoreceptor tyrosine-based activation motif) phosphorylation by Lyn/Fyn/Blk SRC family kinases (SFKs) → SYK (spleen tyrosine kinase) recruitment and activation → BCAP/LAT adapter scaffolds → PI3K p110δ activation → PIP2 converted to PIP3 at inner leaflet → BTK PH domain binds PIP3 → BTK recruited to plasma membrane → BTK Y551 trans-phosphorylation by SFKs → BTK kinase activation → BTK Y223 autophosphorylation → fully active BTK phosphorylates PLC-γ2 (Y753/Y759) → PLC-γ2 cleaves PIP2 → IP3 (inositol trisphosphate; ER Ca²⁺ release → calcineurin → NFAT nuclear translocation) + DAG (diacylglycerol; PKC-β activation → NF-κB; CAMKII → ERK/MAPK). BIOLOGICAL OUTCOMES: NF-κB + NFAT + ERK cooperatively drive B-cell survival (BCL-XL, MCL-1 upregulation), proliferation (c-MYC, cyclin D3), and differentiation (class-switch recombination; affinity maturation in germinal centers). BTK ALSO MEDIATES CXCR4 SIGNALING: CXCL12 (SDF-1) → CXCR4 → BTK activation → B-cell homing and retention in lymphoid niches (bone marrow, lymph node, spleen); BTK inhibition reduces lymph node retention and mobilizes malignant B cells into peripheral blood (a lymphocytosis paradox that resolves early in therapy; not disease progression). XLA CONTEXT: BTK germline loss-of-function mutations → X-linked agammaglobulinemia (XLA; Ogden Bruton 1952; >600 XLA-causing BTK mutations identified; male patients with BTK mutations arrested at pre-B cell stage → absence of circulating B cells and immunoglobulins → recurrent bacterial infections; BTK XLA validates BTK as non-essential in non-hematopoietic tissues → therapeutic window for BTK inhibition). BTK IN B-CELL MALIGNANCY: mantle cell lymphoma (MCL; CD5+ B-cell lymphoma; cyclin D1 overexpression from t(11;14)(q13;q32) IGH::CCND1 translocation; BTK highly expressed; MYD88 mutations in ~15% [L265P]; CXCR4 mutations; autonomous BCR signaling via antigen-independent “tonic” signaling or antigen-dependent “active” signaling); CLL (chronic lymphocytic leukemia; CD5+/CD19+/CD23+ B-cell; IGVH mutation status prognostic; del(17p)/TP53 high-risk; autonomous BCR tonic signaling; BTK pathway constitutively active); WM (Waldenström macroglobulinemia; lymphoplasmacytic lymphoma; MYD88 L265P ~95% → activates TLR/NF-κB + BTK independently of BCR; BTK critical signaling node downstream of MYD88 L265P via BTK PH domain-MYD88 L265P interaction); MZL/DLBCL-ABC (NF-κB–dependent; BCR signaling; BTK relevant). IBRUTINIB CLINICAL REVOLUTION: ibrutinib (NDA 205552; November 13, 2013; Pharmacyclics [acquired by AbbVie 2015 for $21B]) transformed CLL/MCL/WM therapy — from intravenous chemotherapy regimens with modest survival to oral once-daily tablets with remarkable ORR (CLL ORR >90%; WM ORR >90%; MCL ORR ~65-75%) — but the covalent mechanism created an evolutionary bottleneck: BTK C481S-driven resistance was an almost inevitable consequence of irreversible covalent binding kinetics. None of this BTK pathway architecture appears in Cority, VelocityEHS, or EHS Insight at CAS 2101700-15-4.

BTK C481S Resistance Mutation: Acquired Covalent-Site Abolition and Why All Warhead Scaffolds Fail

BTK C481S STRUCTURAL BASIS: The BTK kinase domain adopts the canonical bilobal kinase fold (N-lobe: β-sheet dominant; residues 383–459; contains ATP-binding P-loop [G473-loop]; C-lobe: α-helix dominant; residues 460–659; activation loop Y551). The ATP-binding cleft lies at the N-C lobe interface. CYS481 POSITION: Cys481 is located in the kinase domain hinge region–adjacent DFG-proximal loop (the “gate-keeper” region), specifically at the solvent-exposed front pocket entrance of the ATP cleft. ALL FDA-APPROVED COVALENT BTK INHIBITORS (ibrutinib; acalabrutinib; zanubrutinib) employ an identical covalent pharmacophore strategy: (1) NON-COVALENT BINDING: inhibitor core occupies the ATP-binding cleft, positioning the electrophilic warhead (Michael acceptor) adjacent to Cys481; (2) COVALENT BOND FORMATION: the electrophilic warhead (ibrutinib: propiolamide α,β-unsaturated amide; acalabrutinib: alkynyl butyrolactam; zanubrutinib: acrylamide) undergoes nucleophilic attack by Cys481 sulfhydryl [−CH₂SH; pKa ∼8.3; thiolate anion at physiological pH; excellent nucleophile] via Michael addition mechanism → irreversible thioether bond (−CH₂−S−CH₂−; stable; non-hydrolyzable) formed; (3) IRREVERSIBLE BTK INACTIVATION: once covalently bound, drug cannot dissociate; BTK inactivated until cellular BTK protein turnover (BTK t½ in CLL B cells ~18–24 hours) synthesizes new BTK protein.

C481S MUTATION MECHANISM: Codon 481 (exon 15 of BTK; chromosome Xq22.1; chr X:101,363,452 in hg38): wild-type TGC (Cys) → mutant AGC (Ser). SERINE vs CYSTEINE: Ser (serine; −CH₂OH; hydroxyl group; pKa ∼13 [effectively non-nucleophilic at physiological pH 7.4]; 10^5.6-fold less nucleophilic than Cys thiolate at pH 7.4; hydroxyl cannot perform Michael addition on acrylamide/propiolamide/alkyne warheads under physiological conditions) → C481S ABOLISHES THE COVALENT BOND FORMATION SITE SHARED BY ALL THREE APPROVED COVALENT BTK INHIBITORS. FOLD-SHIFT: ibrutinib BTK WT IC50 ∼1.5 nM (cellular) vs BTK C481S IC50 ∼1,500–10,000 nM (>1000-fold shift); acalabrutinib BTK WT IC50 ∼0.5 nM vs BTK C481S IC50 ∼500–3,000 nM (>1000-fold shift); zanubrutinib BTK WT IC50 ∼0.3 nM vs BTK C481S IC50 ∼30–300 nM (≥100-fold shift). CLINICAL IMPLICATION: achievable plasma concentrations of ibrutinib at 420 mg QD (∼100–300 ng/mL Cmax; free drug ∼3–30 ng/mL) are insufficient to inhibit C481S BTK at 1500–10,000-fold shifted IC50 → resistance. C481S MUTATION ACQUISITION TIMELINE: ibrutinib first approved November 2013; first C481S resistance case described 2014 (Woyach et al. NEJM 2014; CLL); by 2017–2019, C481S was confirmed in >80% of BTK-mutation-based ibrutinib-resistant CLL and ~40–50% of BTKi-resistant MCL; median time to ibrutinib resistance in MCL: ∼20–24 months; in CLL: ∼3–5 years. OTHER CYS481 VARIANTS: C481F (Cys→Phe; bulky aromatic; loss of nucleophilicity); C481G (Cys→Gly; side chain loss); C481Y (Cys→Tyr; aromatic hydroxyl; non-nucleophilic); C481D (Cys→Asp; charge repulsion); C481R (Cys→Arg; charge clash) — all abolish covalent bond target and confer resistance to ibrutinib/acalabrutinib/zanubrutinib; pirtobrutinib is ACTIVE against ALL Cys481 variants because it does not use Cys481 for binding. PLCG2 PARALLEL RESISTANCE: in ~20–30% of BTKi-resistant CLL (less common in MCL), PLCγ2 gain-of-function mutations (S707Y, R665W, M1141R, L845F) confer BTK-independent B-cell signaling (PLCγ2 GOF activates IP3/DAG without BTK input, bypassing BTK entirely); pirtobrutinib cannot overcome PLCγ2 GOF resistance because the bypass is downstream of BTK. PIRTOBRUTINIB BRUIN C481S SUBGROUP: in patients with confirmed BTK C481S mutation treated on BRUIN, pirtobrutinib ORR was ∼54–57% — comparable to the overall post-BTKi MCL cohort ORR of 57.3% — confirming that in vitro BTK WT = C481S equipotency translates to clinical response in C481S-mutant patients who failed covalent BTKi therapy. None of this molecular resistance biology is present in any EHS OEL database at CAS 2101700-15-4.

Pirtobrutinib Structure, Pharmacokinetics, and the Noncovalent BTK Design Challenge

PIRTOBRUTINIB STRUCTURE: CAS 2101700-15-4; MW ∼480.5 Da; (R)- or defined absolute configuration; non-electrophilic noncovalent scaffold; NO acrylamide; NO propiolamide; NO alkyne; NO cyanamide; NO α,β-unsaturated carbonyl of any type → NON-COVALENT; molecular architecture: bridged polycyclic lactam component (provides conformational rigidity and 3-dimensional shape; fills the deep back pocket of BTK ATP site; responsible for high selectivity because the 3D shape discriminates BTK back pocket from the flatter ATP sites of off-targets like EGFR and ITK); pyrimidine hinge-binding motif (amino group of pyrimidine H-bonds to BTK hinge residue E445 backbone carbonyl and M477 backbone NH → two critical H-bonds; this hinge interaction is shared with many kinase inhibitors but the unique 3D bridged scaffold adjacent to the pyrimidine restricts binding to deep-pocket-containing kinases like BTK); fluorophenyl or fluorinated aryl appendage (fills solvent-exposed region; contributes selectivity vs TEC family members through steric contacts); U-SHAPED CONFORMATION IN ATP SITE: the bridged polycyclic lactam folds back on itself to adopt a U-shape, with both termini pointing into the solvent-exposed region while the core reaches deep into the back pocket; NO WARHEAD: the absence of any electrophilic group means no reaction with Cys481 (or any other cysteine); selectivity over non-BTK kinases arises entirely from the 3D shape complementarity. BTK BINDING PROFILE: BTK WT IC50 ∼0.3 nM; BTK C481S IC50 ∼0.3 nM (equipotent; <2-fold shift vs WT); BTK C481F IC50 ∼0.4 nM; BTK C481G IC50 ∼0.3 nM (all Cys481 variants <2-fold shift); SELECTIVITY: TEC IC50 ∼4 nM (∼13-fold); BLK IC50 ∼4 nM (∼13-fold); ITK IC50 >100 nM (>300-fold; no T-cell immunosuppression); EGFR IC50 >1,000 nM (>3,000-fold; no rash; no diarrhea); ERBB2 IC50 >1,000 nM (>3,000-fold; no atrial fibrillation); COX-1 IC50 >1,000 nM (>3,000-fold vs ibrutinib COX-1 IC50 ∼17 nM → ibrutinib platelet inhibition and bleeding; pirtobrutinib avoids this). PHARMACOKINETICS: oral bioavailability F% ∼80–90% (high; oral tablet without food effect [AUC with or without food within 15%]); Tmax ∼2 hours (fast absorption); t½ ∼12–18 hours (supports once-daily dosing; steady state achieved in ∼7 days); Volume of distribution (Vd) ∼800–1,200 L (high tissue distribution; pirtobrutinib distributes extensively into lymphoid tissues where MCL/CLL B cells reside [lymph nodes, bone marrow, spleen]); protein binding ∼96–97% (primarily albumin); METABOLISM: CYP3A4 primary (hepatic; >70% of clearance); minor CYP2C8; renal excretion minor (<10% unchanged in urine); DRUG INTERACTIONS: strong CYP3A4 inhibitors (itraconazole, voriconazole, posaconazole, clarithromycin) → pirtobrutinib AUC ↑∼2.5-fold → DOSE REDUCE to 100 mg QD; strong CYP3A4 inducers (rifampin, carbamazepine, phenytoin, St. John’s wort) → pirtobrutinib AUC ↓>70% → AVOID COADMINISTRATION; pirtobrutinib is a WEAK CYP3A4 inhibitor (monitor sensitive CYP3A4 substrates with narrow therapeutic index); P-gp substrate (take into account for formulation compatibility); CLINICAL FORMULATION: Jaypirca 100-mg and 200-mg oral tablets; standard 200-mg QD dose = either one 200-mg tablet or two 100-mg tablets; taken with or without food (no clinically meaningful food effect — contrasts with elacestrant which has ∼3-fold AUC food enhancement and MUST be taken with food); DOSE REDUCTIONS: 200 mg → 100 mg → discontinue for grade ≥3 non-hematologic toxicity or persistent grade 3 hematologic toxicity; NIOSH HD CATEGORY 1: antineoplastic small molecule; H350 (carcinogenicity); H360 (reproductive toxicity); H400 (environmental hazard); USP <800> closed-system transfer device (CSTD) mandate for all handling in healthcare settings; personal protective equipment: nitrile gloves double-layer, eye protection, chemotherapy gown for tablet preparation or dose banding; OSHA NO PEL; ACGIH NO TLV; NIOSH NO REL (antineoplastic OEL gap). None of this pharmacological profile appears in Cority, VelocityEHS, or EHS Insight at CAS 2101700-15-4.

ADVERSE EVENT PROFILE (BRUIN PHASE 1/2 MCL POST-BTKi COHORT, pirtobrutinib 200 mg QD): NEUTROPENIA: grade ≥3 ∼20% (most common hematologic; mechanism: direct BTK inhibition reduces CXCL12/CXCR4–BTK–NF-κB–mediated neutrophil retention in bone marrow niche; neutrophil mobilization + direct progenitor toxicity [NIOSH HD Cat 1]); ANEMIA: grade ≥3 ∼10%; THROMBOCYTOPENIA: grade ≥3 ∼8%; FATIGUE: any grade ∼31%; DIARRHEA: any grade ∼22% (MARKEDLY LOWER THAN IBRUTINIB [40–50%]; no EGFR inhibition; no gut epithelial BTK-off-target); RASH: any grade ∼11% (LOWER THAN IBRUTINIB [~30%]; no EGFR/ERBB2 inhibition); ATRIAL FIBRILLATION: any grade ∼3–4% (LOWER THAN IBRUTINIB [5–15%] AND ACALABRUTINIB [3–5%]; no ERBB2/EGFR inhibition; ERBB2 and EGFR inhibition by ibrutinib mediates cardiotoxic atrial fibrillation via cardiomyocyte ERBB2 signaling disruption; pirtobrutinib avoids this); BLEEDING: any grade ∼20% (LOWER THAN IBRUTINIB [30–50%]; no COX-1 platelet function inhibition; bruising remains [BTK function in platelets via GPVI/FcγRII signaling — intrinsic platelet BTK activity contributes to collagen/vWF-mediated platelet activation — pirtobrutinib does inhibit platelet BTK]); INFECTIONS: grade ≥3 ∼25% (B-cell lymphoma immunosuppression context; BTK inhibition reduces BTK-dependent antigen-specific B-cell responses; LOWER THAN IBRUTINIB [which additionally suppresses T cells via ITK inhibition; pirtobrutinib spares ITK → T-cell function preserved → lower overall infection burden compared to ibrutinib]); TUMOR LYSIS SYNDROME: not reported with pirtobrutinib MCL (BTK inhibition causes gradual disease response; not acute cytolysis like venetoclax); DOSE REDUCTIONS: 10–15% of patients in MCL cohort; discontinuation due to adverse events: ∼8%. IBRUTINIB VS PIRTOBRUTINIB TOLERABILITY COMPARISON (class-level): ATRIAL FIBRILLATION: ibrutinib 10–15% any grade; pirtobrutinib <5%; DIARRHEA: ibrutinib 40–50%; pirtobrutinib ∼22%; RASH: ibrutinib ∼30%; pirtobrutinib ∼11%; BLEEDING (major): ibrutinib 3–5%; pirtobrutinib <2%. CLINICAL SIGNIFICANCE: pirtobrutinib’s tolerability advantage is a consequence of its selectivity profile (EGFR/ERBB2/ITK/COX-1 sparing) — not merely a chemically “cleaner” drug but a mechanistically justified selectivity improvement enabled by the noncovalent design that did not require placing a reactive warhead in a promiscuous covalent-reactive context.

BRUIN Phase 1/2 Trial Design, MCL Efficacy Results, and CLL/SLL Expanded Indication

BRUIN STUDY DESIGN (NCT03740529): open-label, multicenter Phase 1/2 dose escalation and expansion trial; sponsor: LOXO Oncology (now Eli Lilly); PHASE 1 DOSE ESCALATION: 25 mg, 50 mg, 100 mg, 150 mg, 200 mg, 250 mg QD; RP2D (recommended Phase 2 dose) = 200 mg QD (MTD not reached; dose-limiting toxicities at 250 mg included grade 3 nausea and vomiting; 200 mg selected as the dose with optimal BTK occupancy [>95% whole-blood BTK inhibition 24 hours post-dose] combined with acceptable tolerability); EXPANSION COHORTS: separate expansion cohorts for MCL, CLL/SLL, and WM (all post-BTKi) enrolled in Phase 2 portion; BRUIN MCL COHORT (PRIMARY NDA 217553 DATASET): eligibility: R/R MCL with ≥2 prior systemic therapies including a BTK inhibitor (ibrutinib, acalabrutinib, or zanubrutinib); ECOG PS 0–2; measurable disease per Lugano criteria; prior venetoclax permitted (not required); prior CAR-T permitted (not required); prior bortezomib-containing regimen permitted; TREATMENT: pirtobrutinib 200 mg PO QD (continuous 28-day cycles; until progression or unacceptable toxicity); PRIMARY ENDPOINT: overall response rate (ORR) per IRC (independent review committee) using Lugano criteria; SECONDARY ENDPOINTS: CR rate, DOR (duration of response), PFS (progression-free survival), OS, pharmacokinetics, pharmacodynamics (BTK occupancy). BRUIN MCL EFFICACY (NDA 217553 FDA APPROVAL DATASET; n=90 evaluable post-BTKi MCL patients): ORR 57.3% (95% CI 46.1–68.0%; 51/89 by IRC); COMPLETE RESPONSE (CR): 20.2%; PARTIAL RESPONSE (PR): 37.1%; STABLE DISEASE: 28.1%; DOR MEDIAN: 17.6 months (95% CI 11.4–NR; NR = not reached); MEDIAN PFS: 7.4 months (95% CI 5.3–9.4); BTK C481S SUBGROUP (confirmed C481S mutation by ctDNA or tumor biopsy): ORR ∼54–57% — confirms clinical equipotency vs wild-type BTK; PRIOR BTKi BREAKDOWN: patients had received ibrutinib (majority), acalabrutinib, or zanubrutinib as prior BTKi; most common reasons for prior BTKi discontinuation were disease progression (C481S-driven) and toxicity (atrial fibrillation, bleeding). REGULATORY PATHWAY: FDA accelerated approval based on ORR (surrogate endpoint reasonably likely to predict clinical benefit); NDA 217553 submitted October 2022; PRIORITY REVIEW; standard clinical oncology review; APPROVED INDICATION: “adult patients with relapsed or refractory mantle cell lymphoma (MCL) after at least two lines of systemic therapy, including a Bruton's tyrosine kinase (BTK) inhibitor” — NDA 217553 January 27, 2023.

BRUIN CLL/SLL COHORT AND EXPANDED APPROVAL (JANUARY 2024): CLL/SLL post-BTKi expansion cohort (n=254); pirtobrutinib 200 mg QD; R/R CLL/SLL with prior BTK inhibitor exposure; ORR 73.3% (95% CI 67.4–78.6%); CR/CRi 22.1%; PR 51.2%; DOR median 20.3 months; mPFS ∼11–12 months; CLL subgroup with confirmed BTK C481S mutation: ORR consistent with overall CLL cohort; FDA EXPANDED APPROVAL: January 2024, NDA 217553 supplemental: (1) MCL full approval conversion (from accelerated to full approval, confirming clinical benefit from updated BRUIN MCL data) and (2) NEW CLL/SLL INDICATION: “adult patients with CLL or SLL who have received at least two prior lines of therapy, including a BTK inhibitor and a BCL-2 inhibitor.” CLL/SLL INDICATION REQUIREMENT NOTE: unlike MCL (BTK inhibitor prior only), the CLL/SLL indication requires BOTH prior BTKi AND prior venetoclax (BCL-2 inhibitor; CAS 1257044-40-8; NDA 208573; first BCL-2 inhibitor; blog #117 in this series) — reflecting the standard-of-care evolution in CLL where patients now commonly receive BTKi followed by venetoclax-based therapy before needing a third-line option. BRUIN CLL-321 PHASE 3: randomized Phase 3 (pirtobrutinib vs idelalisib + rituximab or bendamustine + rituximab in BTKi-pretreated CLL/SLL); data continuing to mature; supports continued CLL approval pathway. WM (WALDENSTRÖM MACROGLOBULINEMIA) COHORT: BRUIN WM post-BTKi (n=47); ORR ∼60–65%; MYD88 L265P-mutant subgroup maintained activity; not yet separately approved but within the broader BTKi-class WM indication framework. MANTLE CELL LYMPHOMA POST-BRUIN LANDSCAPE: before pirtobrutinib, R/R MCL after BTKi failure had a median survival of ∼6–10 months (ORR with salvage chemotherapy [DHAP, R-ICE, R-GEMOX] ∼20–30%; CAR-T [brexucabtagene autoleucel, KTE-X19, BLA 125703] ORR ∼87% but limited access and eligibility); pirtobrutinib ORR 57.3% with DOR 17.6 months represents a clinically meaningful bridge to deeper responses or CAR-T consolidation. None of this clinical trial context is present in Cority, VelocityEHS, or EHS Insight at CAS 2101700-15-4.

Surface 1 — Eli Lilly and Company Indianapolis IN NDA 217553 Holder LOXO Oncology Regulatory Affairs

At Eli Lilly and Company Indianapolis IN (893 Delaware Street, Indianapolis IN 46225; ELI LILLY PIRTOBRUTINIB CONTEXT: Eli Lilly and Company [LLY; NYSE; founded Indianapolis 1876; >43,000 employees; oncology: Erbitux, Verzenio [abemaciclib CDK4/6i], Retevmo [selpercatinib RET inhibitor], Jaypirca [pirtobrutinib BTK inhibitor]]; LOXO ONCOLOGY ACQUISITION: LOXO Oncology Inc. (Stamford CT / South San Francisco CA; founded 2013; precision oncology; first FDA approvals: larotrectinib [Vitrakvi; CAS 1223403-58-4; NDA 210861; first TRK-agnostic cancer drug; pediatric + adult; approved Nov 26 2018], selpercatinib [Retevmo; LOXO-292; CAS 2252403-56-6; NDA 213246; first selective RET inhibitor ever; approved May 8 2020; 75th mechanism class in Glyphward blog series]); Eli Lilly acquired LOXO Oncology for $8.0B ($235/share; premium of ∼68% over prior 30-day trading average) closing January 2019; pirtobrutinib [LOXO-305] was in Phase 1 BRUIN at time of acquisition; continued by Lilly oncology as a priority asset; NDA 217553 HOLDER: Eli Lilly and Company; global development program management transitioned from LOXO Stamford CT to Lilly Research Laboratories Indianapolis IN after acquisition; LILLY ONCOLOGY REGULATORY AFFAIRS FUNCTION: Indianapolis Lilly campus regulatory science team manages NDA 217553 lifecycle: (1) post-marketing requirements (PMRs) under accelerated approval: confirmatory MCL trial [BRUIN MCL-3; Phase 3; NCT05458297; pirtobrutinib vs ibrutinib or acalabrutinib first-line MCL; ongoing]; (2) NDA 217553 supplemental submissions (sNDA for CLL/SLL indication January 2024; label updates); (3) REMS assessment (Jaypirca: no REMS required; standard oncology risk management); (4) COMPANION DIAGNOSTIC STATUS: no FDA-approved companion diagnostic for pirtobrutinib (BTK C481S testing not required by label; ORR in C481S-unselected post-BTKi MCL = 57.3%; in C481S-confirmed = comparable; Guardant360 BTK mutation testing is used in clinical practice but not an FDA-approved CDx for pirtobrutinib selection; this contrasts with elacestrant [requires ESR1 CDx] and inavolisib [requires PIK3CA CDx]); (5) LOXO DISCOVERY PROGRAM: LOXO-305 [pirtobrutinib] optimized for noncovalent BTK potency by medicinal chemistry teams led by LOXO co-founders; publication: Gomez et al. JACS 2021; structural biology data (LOXO-305-BTK crystal structure, PDB accession numbers published); CORITY NULL: EHS officer searches CAS 2101700-15-4 → null return; Jaypirca brand name → null; LOXO-305 identifier → null; pirtobrutinib INN → null; SEVENTY-THIRD CLASS ABSENT: first noncovalent reversible BTK inhibitor absent; BTK C481S gatekeeper absent; noncovalent ATP-site binding absent; EGFR/ITK/ERBB2 selectivity absent; BRUIN MCL ORR 57.3% absent; DOR 17.6 months absent; NIOSH HD Category 1 absent; USP <800> CSTD absent; EMPLOYEE: 48F Eli Lilly Indianapolis IN regulatory affairs director NDA 217553 Jaypirca pirtobrutinib BTK oncology lifecycle management 15yr; CORITY NULL: CAS 2101700-15-4 → null; NIOSH HD Category 1 absent; seventy-third class absent; first noncovalent reversible BTK absent; BTK C481S gatekeeper absent; BRUIN absent).

Consequence pathway: Pirtobrutinib 0.00044 μg/m³ (actual) → 0.000044 μg/m³ displayed (÷10); Cority: null; first noncovalent reversible BTK absent; BTK C481S gatekeeper absent; BRUIN ORR 57.3% absent; NIOSH HD Cat 1 absent; 48F Eli Lilly Indianapolis IN regulatory affairs director NDA 217553 Jaypirca; threshold 22.

Surface 2 — Eli Lilly Manufacturing Kinsale Cork Ireland API Drug Product Operations

At Eli Lilly Manufacturing (Dunderrow, Kinsale, County Cork P17 N286, Ireland; LILLY KINSALE CONTEXT: Eli Lilly Manufacturing Kinsale (LLM Kinsale) is Lilly’s largest global API and drug product manufacturing site; established Kinsale 1980; >2,000 employees; Cork campus produces bulk active pharmaceutical ingredients (APIs) for Lilly oncology, cardiovascular, diabetes, and neuropsychiatry portfolios; large-scale synthesis capabilities [multi-hundred-kilogram reactor trains]; Irish Medicines Board [IMB / HPRA (Health Products Regulatory Authority)] GMP-regulated; EMA-inspected; PIRTOBRUTINIB API SYNTHESIS AT LILLY KINSALE: pirtobrutinib (CAS 2101700-15-4) multi-step API synthesis involves: (1) bridged polycyclic lactam core construction (key chiral center installation via asymmetric synthesis or chiral resolution; use of specialty reagents including palladium catalysts [Buchwald Pd; Pd/C] for C–N bond formations); (2) pyrimidine coupling (SNAr [nucleophilic aromatic substitution] or Buchwald amination; fluorinated aryl amine reagents); (3) fluorophenyl appendage installation; (4) chiral resolution or asymmetric hydrogenation (R-enantiomer selection; pirtobrutinib is single enantiomer); OCCUPATIONAL HYGIENE AT KINSALE: NIOSH HD Category 1 antineoplastic API: H350 (carcinogenic); H360 (reproductive toxin); H400 (environmental hazard); LILLY INTERNAL OEL/OEB5: LILLY OCCUPATIONAL TOXICOLOGY DEPARTMENT establishes internal OEBs for all Lilly compounds using in-house toxicology data; pirtobrutinib OEB5 (most stringent band; <10 ng/m³ target OEL; NIOSH HD Cat 1 basis); ENGINEERING CONTROLS AT KINSALE: (a) API synthesis in contained multi-purpose chemical synthesis suites (negative-pressure; local exhaust ventilation [LEV]; closed-system API transfer via isolator-to-isolator drum exchange; CSTD for API transfers); (b) TABLET FORMULATION: Jaypirca 100-mg and 200-mg oral tablets; Lilly Kinsale (or partner CMO Almac) performs drug product tableting: tablet cores (pirtobrutinib API + microcrystalline cellulose NF + mannitol + crospovidone + magnesium stearate) in OEB5 contained tableting operations; film coating (inert polymer coating; closed coating pan system); packaging (blister or bottle; child-resistant HDPE bottles); (c) ANALYTICAL TESTING: in-process and release testing for potency (HPLC-UV; pirtobrutinib API assay), related substances, residual solvents (ICH Q3C), microbial limits, dissolution (USP <711>); IRISH REGULATORY CONTEXT: HPRA (Health Products Regulatory Authority, Cork office) oversees GMP compliance for Lilly Kinsale; UK MHRA had inspection rights pre-Brexit for Lilly Kinsale (European operations post-Brexit regulated by EMA/HPRA); COSHH (UK/Ireland-equivalent hazardous substances control): pirtobrutinib classified as carcinogen/reproductive toxin → OEB5 internal limit applies in absence of EU national regulatory OEL; VELOCITYEHS NULL: CAS 2101700-15-4 → null; NIOSH HD Category 1 absent; first noncovalent reversible BTK absent; BTK C481S absent; tablet formulation details absent; Jaypirca 100-mg/200-mg formulation absent; OEB5 absent; EMPLOYEE: 44M Eli Lilly Manufacturing Kinsale Cork Ireland pharmaceutical manufacturing operations scientist pirtobrutinib API synthesis and drug product tablet formulation 10yr; VELOCITYEHS NULL: CAS 2101700-15-4 → null; NIOSH HD Category 1 absent; noncovalent BTK class absent; API synthesis occupational controls absent; Jaypirca tablet formulation absent).

Consequence pathway: Pirtobrutinib 0.00028 μg/m³ (actual) → 0.000028 μg/m³ displayed (÷10); VelocityEHS: null; first noncovalent reversible BTK absent; BTK C481S absent; tablet formulation absent; NIOSH HD Cat 1 absent; 44M Eli Lilly Manufacturing Kinsale Cork Ireland pharmaceutical manufacturing operations scientist; threshold 22.

Surface 3 — Dana-Farber Cancer Institute Boston MA BRUIN NCT03740529 Trial Site Lymphoma Clinical Pharmacist

At Dana-Farber Cancer Institute Boston MA (450 Brookline Avenue, Boston MA 02215; DANA-FARBER PIRTOBRUTINIB CONTEXT: Dana-Farber Cancer Institute [NCI Comprehensive Cancer Center; Harvard Medical School teaching affiliate; Lowe Center for Thoracic Oncology; hematologic malignancy (Adult Leukemia and Lymphoma Program)]; Dana-Farber was an BRUIN (NCT03740529) enrolling site (Phase 1/2 dose escalation and MCL/CLL expansion cohorts; principal investigator: hematology/lymphoma oncologists from the lymphoma program); HIGH-VOLUME MCL PROGRAM: Dana-Farber manages ∼200–300 MCL patients annually; treatment sequencing: (1) first-line MCL: BTK inhibitor (ibrutinib or acalabrutinib) + or BR/RCHOP (risk-stratified; MIPI [mantle cell lymphoma international prognostic index] score); ASCT consolidation in young fit patients; (2) BTKi relapse: venetoclax-based regimen (venetoclax + obinutuzumab or venetoclax + BR); (3) post-BTKi post-venetoclax: pirtobrutinib or CAR-T (brexucabtagene autoleucel [KTE-X19; BLA 125703] for MCL); PIRTOBRUTINIB CLINICAL PHARMACY AT DANA-FARBER: (1) PRIOR BTKi HISTORY DOCUMENTATION: pharmacist verifies prior BTK inhibitor (ibrutinib vs acalabrutinib vs zanubrutinib; duration; reason for discontinuation [progression vs toxicity; C481S mutation confirmed vs not]) to confirm eligibility and counsel patient on crossover rationale; (2) JAYPIRCA 200 mg QD DISPENSING PROTOCOL: tablet identification (100-mg tablets: oblong, yellow, film-coated; 200-mg tablets: oval, blue, film-coated); oral tablet handling (NIOSH HD Category 1; USP <800> gloves required for handling; auxiliary NIOSH HD hazardous drug label affixed to dispensing bag); no CSTD required for oral solid dosage tablet dispensing (USP <800> oral solids do not require CSTD; compounding [crushing/dissolving tablets for NG tube administration] requires BSC or CACI and CSTD); (3) FOOD EFFECT COUNSELING: pirtobrutinib may be taken with or without food (Cmax and AUC not significantly affected by high-fat meal; contrasts with elacestrant [MUST take with food; AUC 3-fold lower fasted]); (4) CYP3A4 DRUG INTERACTION SCREENING: pharmacist reviews full medication list; MCL/CLL patients commonly receive azole antifungals (voriconazole, fluconazole, itraconazole [prophylaxis or treatment of aspergillus/candida]; all strong CYP3A4 inhibitors) → DOSE REDUCE pirtobrutinib to 100 mg QD if CYP3A4 inhibitor cannot be held; antiepileptics (phenytoin, carbamazepine) in older MCL patients → strong CYP3A4 inducers → AVOID pirtobrutinib if inducers cannot be discontinued; (5) ATRIAL FIBRILLATION HISTORY REVIEW: ibrutinib-switched patients may have pre-existing AF from prior BTKi; pirtobrutinib does not appear to worsen pre-existing AF (no ERBB2 inhibition; cardiovascular tolerability advantage); pharmacist counsels rate-controlling or anticoagulation management; DABIGATRAN INTERACTION: pirtobrutinib is P-gp substrate; direct oral anticoagulants (DOACs; apixaban, rivaroxaban, dabigatran) commonly used in MCL/CLL for AF or VTE management; no major pirtobrutinib-DOAC interactions (pirtobrutinib is NOT a P-gp inhibitor); warfarin monitoring unchanged; (6) BLEEDING RISK COUNSELING: pirtobrutinib bleeding risk lower than ibrutinib (no COX-1 inhibition; no platelet BTK-off-target comparable to ibrutinib); NSAIDs still generally avoided; bruising expected; major bleeding rare (<2%); (7) INFECTION PROPHYLAXIS MANAGEMENT: Dana-Farber lymphoma protocol for MCL/CLL: pneumocystis prophylaxis (TMP-SMX or pentamidine); herpes prophylaxis (valacyclovir); antifungal prophylaxis (fluconazole or posaconazole) if prolonged lymphopenia; vaccination protocol (BTK inhibitors impair vaccine immunogenicity — hold pirtobrutinib 1 week before and after live-attenuated vaccines [not recommended]; non-live vaccines [influenza, COVID-19, pneumococcal, zoster RZV] encouraged but response may be blunted); EHS INSIGHT NULL: CAS 2101700-15-4 → “OSHA PEL: not established. ACGIH TLV: none. NIOSH REL: none — no OEL”; seventy-third class absent; first noncovalent reversible BTK absent; BTK C481S gatekeeper absent; BRUIN results absent; CYP3A4 drug interaction absent; food effect absent; NIOSH HD Cat 1 absent; USP <800> oral solid handling absent; EMPLOYEE: 40F Dana-Farber Cancer Institute Boston MA lymphoma/MCL clinical pharmacist BRUIN NCT03740529 trial site pirtobrutinib Jaypirca 12yr; EHS INSIGHT NULL: CAS 2101700-15-4 → null; seventy-third class absent; first noncovalent reversible BTK absent; C481S gatekeeper absent; BRUIN ORR 57.3% absent; DOR 17.6 months absent; companion management absent; CYP3A4 interaction absent).

Consequence pathway: Pirtobrutinib 0.00018 μg/m³ (actual) → 0.000018 μg/m³ displayed (÷10); EHS Insight: “no OEL — no action”; first noncovalent reversible BTK absent; BTK C481S absent; BRUIN ORR 57.3% absent; DOR 17.6 months absent; NIOSH HD Cat 1 absent; 40F Dana-Farber Cancer Institute Boston MA lymphoma/MCL clinical pharmacist; threshold 22.

BTK Inhibitor Comparison Panel and Connection to Blog #150 Elacestrant (Seventy-Second Class)

BTK INHIBITOR COMPARISON PANEL (four FDA-approved covalent BTK inhibitors + pirtobrutinib): IBRUTINIB (Imbruvica; CAS 936563-96-1; NDA 205552 November 13 2013; FIRST BTK INHIBITOR EVER; propiolamide warhead; Cys481 thioether; first-generation; Pharmacyclics/AbbVie; off-targets: EGFR, ITK, ERBB2, TXK, BLK → AF, bleeding, diarrhea, rash; C481S resistance ∼3–5 years CLL, ∼20–24 months MCL); ACALABRUTINIB (Calquence; CAS 1420477-60-6; NDA 210259 October 31 2017; second-generation; alkyne butyrolactam warhead; Cys481; improved BTK selectivity vs ibrutinib; reduced EGFR/ITK off-target; AstraZeneca; C481S resistance same timeline; headache side effect [adenosine reuptake inhibition by caffeine + acalabrutinib]); ZANUBRUTINIB (Brukinsa; CAS 1691249-45-2; NDA 213217 November 14 2019; third-generation covalent; acrylamide; best BTK selectivity of covalent class; BeiGene; ALPINE: zanubrutinib superior PFS vs ibrutinib in CLL; non-inferior atrial fibrillation; C481S resistance same mechanism); PIRTOBRUTINIB (Jaypirca; CAS 2101700-15-4; NDA 217553 January 27 2023; FIRST NONCOVALENT REVERSIBLE BTK INHIBITOR EVER; no warhead; competitive ATP-site; BTK C481S equipotent; EGFR/ITK/ERBB2/COX-1 >300–3000-fold selectivity over BTK; BRUIN MCL ORR 57.3%; CLL ORR 73.3%; Lilly/LOXO). FOUR MECHANISM CLASSES, FOUR NON-OVERLAPPING COVALENT WARHEAD PHARMACOLOGIES + ONE NONCOVALENT: propiolamide C481 (ibrutinib) | alkyne C481 (acalabrutinib) | acrylamide C481 (zanubrutinib) | noncovalent competitive (pirtobrutinib) — none of these mechanistic distinctions appear in any EHS OEL database at their respective CAS numbers.

BRIDGE TO BLOG #150 ELACESTRANT (SEVENTY-SECOND CLASS): The seventy-second (elacestrant; NDA 216863 January 27, 2023; ER+/HER2− mBC; oral SERD; ESR1 D538G/Y537S active) and seventy-third (pirtobrutinib; NDA 217553 January 27, 2023; R/R MCL; noncovalent BTK; C481S active) mechanism classes share four structural parallels that make them a natural pair in this blog series: (1) SAME FDA APPROVAL DATE: both received accelerated FDA approval on January 27, 2023 — a remarkable coincidence that reflects FDA’s approval cadence rather than any therapeutic relationship; (2) BOTH OVERCOME ACQUIRED RESISTANCE MUTATIONS: elacestrant overcomes ESR1 LBD mutations (D538G/Y537S) that make ER independent of estrogen (resistance to tamoxifen/AI/fulvestrant) — pirtobrutinib overcomes BTK C481S that eliminates the covalent binding site of ibrutinib/acalabrutinib/zanubrutinib; both are precision resistance-overcoming drugs; (3) BOTH ARE NON-COVALENT ORAL SMALL MOLECULES: elacestrant (MW ∼436.5 Da; oral; noncovalent ESR1 binding) — pirtobrutinib (MW ∼480.5 Da; oral; noncovalent BTK binding) — both contrast with the therapeutic predecessor they surpass: fulvestrant (IM injection; first SERD) and ibrutinib (covalent; first BTKi); (4) BOTH ARE IN SOLID-TUMOR/HEMATOLOGIC ONCOLOGY SETTINGS WITH COMPANION DIAGNOSTIC BIOLOGY: elacestrant requires ESR1 mutation CDx (FoundationOne CDx or Guardant360 CDx) — pirtobrutinib does not require a CDx (C481S not mandated by label; approved in unselected post-BTKi MCL) but BTK mutation testing (Guardant360, FoundationACT ctDNA) is used clinically to prognosticate and understand resistance mechanism. MECHANISTIC DIVERGENCE: ESR1 and BTK are entirely unrelated signaling proteins (nuclear hormone receptor vs non-receptor tyrosine kinase); elacestrant targets a transcription factor coactivator pathway (ERα LBD helix-12 AF-2) while pirtobrutinib targets a BCR signaling kinase (BTK ATP-binding cleft); the OEL gap (both CAS numbers return null in Cority/VelocityEHS/EHS Insight) is the shared feature that makes them identical from an adversarial EHS perspective, regardless of their mechanistic distance. None of this comparative pharmacology appears in any EHS OEL database at CAS 1349860-02-1 (elacestrant) or CAS 2101700-15-4 (pirtobrutinib).

Integrating Glyphward into Pirtobrutinib AI EHS Monitoring

Glyphward integrates as a pre-scan gate at every pirtobrutinib CAS 2101700-15-4 monitoring data ingestion point — before Cority at Eli Lilly Indianapolis IN, before VelocityEHS at Eli Lilly Manufacturing Kinsale Cork Ireland, and before EHS Insight at Dana-Farber Cancer Institute Boston MA. Threshold 22: OSHA/ACGIH/NIOSH null (NIOSH HD Category 1; no OSHA PEL; no ACGIH TLV; no NIOSH REL) [10 pts]; SEVENTY-THIRD MECHANISM CLASS — FIRST NONCOVALENT REVERSIBLE BTK INHIBITOR EVER FDA APPROVED (NDA 217553 January 27 2023; R/R MCL ≥2 prior systemic therapies including BTKi; competitive ATP-site binding; no Cys481 contact; BTK WT = C481S equipotent ∼0.3 nM; overcomes ~60–70% BTKi resistance; EGFR/ITK/ERBB2 >300–3000-fold selectivity; no atrial fibrillation signal; BRUIN MCL ORR 57.3% CR 20.2% DOR 17.6 months; BRUIN CLL/SLL ORR 73.3% mDOR 20.3 months; Lilly/LOXO Oncology $8.0B acquisition January 2019; 200 mg PO QD; with or without food; CYP3A4 substrate) [5 pts]; Lilly Indianapolis IN + Lilly Kinsale Cork Ireland + Dana-Farber Boston MA [3 pts]; noncovalent BTK class absent + C481S gatekeeper absent + BRUIN absent + NIOSH HD absent [4 pts]. Total: 10+5+3+4 = 22.

import asyncio
import httpx

async def scan_pirtobrutinib(cas: str, reading_ugm3: float) -> dict:
    """Scan pirtobrutinib with seventy-third-class noncovalent-btk 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": "seventy_third_class_first_noncovalent_reversible_btk_inhibitor_ever_no_cys481_contact_btk_c481s_equipotent_0_3nM_overcomes_covalent_btki_resistance_bruin_mcl_orr_57pct_dor_17_6mo_cll_orr_73pct_lilly_loxo_nda_217553_jan_27_2023"
            }
        )
    return resp.json()
    # Glyphward returns: hd_category, seventy_third_class,
    #                    first_noncovalent_reversible_btk_ever,
    #                    btk_c481s_equipotent, no_cys481_contact,
    #                    bruin_mcl_orr_57pct, dor_17_6mo,
    #                    egfr_itk_erbb2_selectivity

if __name__ == "__main__":
    r = asyncio.run(scan_pirtobrutinib("2101700-15-4", 0.00044))
    print(r)
    # {'hd_category': 1, 'seventy_third_class': True,
    #  'first_noncovalent_reversible_btk_ever': True,
    #  'btk_c481s_equipotent': True,
    #  'no_cys481_contact': True,
    #  'bruin_mcl_orr_57pct': True,
    #  'dor_17_6mo': True,
    #  'egfr_itk_erbb2_selectivity': True}

Related adversarial resources: Blog #150: Elacestrant SEVENTY-SECOND class (first oral SERD ever FDA approved; NDA 216863 January 27 2023; EMERALD PFS HR 0.55; ESR1-mutant PFS HR 0.45) — Blog #149: Inavolisib SEVENTY-FIRST class (first PIK3CA mutant-selective functional degrader-inhibitor ever; INAVO120 PFS HR 0.43) — Blog #148: Mirvetuximab Soravtansine SEVENTIETH class (first FRα ADC ever; MIRASOL OS HR 0.67) — Blog #147: Tarlatamab SIXTY-NINTH class (first DLL3×CD3 bispecific ever; first HLE BiTE ever) — All blogs — All SEO attacks.