Targeted protein degradation
52 articles
Why BRD9 PROTACs underperform in mice, and a humanized-E3 fix
- Widely used CRBN- and VHL-based BRD9 degraders such as dBRD9 and VZ185 are much less potent in mouse cells, even though BRD9 itself is highly conserved.
- The gap points to species differences in the E3 ligases, notably the Crbn I391 residue and structural variation in VHL, which likely hamper ternary complex formation.
- Expressing human CRBN or VHL, or introducing a CrbnI391V mutation, restored potency in mouse cells and improved BRD9 degradation in vivo.
Anyone who has watched a PROTAC look great in human lines and flat in a mouse efficacy study will recognize this. It is a reminder that degrader PK/PD in rodents can fail for E3 reasons rather than compound reasons, so a CrbnI391V or humanized-E3 model is worth setting up early. It also argues for profiling ternary complex formation across species before reading a negative in vivo result as a dead series.
Improving PROTAC-Mediated Degradation in Mouse Models: BRD9 as a Case Study ↗
Fumarate-tagged TTK inhibitor turns into a monovalent degrader via RNF126
- Appending an electrophilic monomethyl fumarate handle to a TTK inhibitor gave a single-warhead degrader, with no E3 ligand attached.
- The lead compound drove TTK degradation and showed stronger antiproliferative activity than the parent inhibitor across several cancer cell lines.
- Mechanistic work points to the E3 ligase RNF126, which the compound stabilizes in complex with TTK, leading to ubiquitination and proteasomal turnover.
Monovalent degraders are attractive because you keep the molecular weight and permeability of a plain inhibitor. The catch is that a fumarate handle is a cysteine-reactive group, so I'd want proteome-wide reactivity data before believing RNF126 is the whole story. Still, if the handle transfers across kinase scaffolds, it's a cheap trick to try on any inhibitor series you already own.
A DNA-based PROTAC degrades CENPB in TKI-resistant lung cancer models
- CENPB, the sequence-specific DNA-binding protein at centromeres, is overexpressed in aggressive cancers, yet has no direct inhibitors.
- CENPB OligoTAC links a CENPB-binding oligodeoxynucleotide to an E3 ligase ligand, driving CENPB ubiquitination and proteasomal degradation, centromere disruption and apoptosis.
- It was active in NSCLC models resistant to first-, second- and third-generation TKIs, with little toxicity to normal cells, good serum stability and a favorable in vivo PK and tolerability profile.
Using the protein's own DNA recognition sequence as the warhead sidesteps the need for a small-molecule pocket, which is the appeal for transcription-factor-like targets. The open questions I would press on are delivery beyond mouse models, oligonucleotide manufacturing cost, and whether the selectivity for tumor over normal cells holds up when CENPB is expressed everywhere.
Centromere-Targeting Chimeras for Combating Cancer Drug Resistance ↗
Much of the PROTAC target-engagement spread is exposure, not E3 recognition
- Twenty PROTACs with varied E3 ligands, linkers and target binders were profiled in intracellular NanoBRET competition assays against cereblon and VHL tracers.
- Apparent potency spread widely when referenced to applied concentration, and passive Caco-2 permeability explained little of it.
- Correcting for measured intracellular unbound exposure shrank the spread dramatically, matching values from permeabilized cells.
Before I read a PROTAC SAR table as E3 affinity, I'd now ask what the cell actually saw. If most of the shift is unbound exposure, linker tweaks that look like potency gains may just be permeability gains, and measuring exposure early keeps us from chasing the wrong variable.
A covalent ligand at cereblon's cryptic Cys287 locks the E3 ligase open and blocks IMiD-driven degradation
- Cysteine-directed chemoproteomic screening found covalent ligands for Cys287, an allosteric pocket far from the thalidomide-binding site.
- Lead VVD-105917 broadly blocks degradation of neosubstrates driven by IMiDs and CELMoDs.
- Cryo-EM shows it traps cereblon in its open, inactive state, and ligand order matters. A previously reported ligand at the same site promotes closure instead, so the pocket is 'sign-switchable'.
Every CRBN drug so far sits in one orthosteric pocket, so a covalent handle that controls the open/closed switch is a genuinely new knob. A pan-inhibitor is an excellent tool to dissect degrader mechanisms and rescue off-target degradation. A site that can push either way also means a degrader-enhancing ligand might be hiding in the same pocket. This is a preprint, so wait for review.
Allosteric covalent inhibition of cereblon through cryptic cysteine targeting ↗
Molecular glue RPT04402 restores PP2A trimer assembly in high-grade uterine cancer
- The paper describes RPT04402, a molecular glue that restores formation of the PP2A AαB56αC heterotrimer in high-grade uterine cancer.
- Recurrent PPP2R1A scaffold mutations in these tumors impair holoenzyme assembly, which the glue is designed to rescue.
- Company reports describe regressions in preclinical PP2A-mutant models and a license to SpringWorks; this summary rests on the title and secondary sources, not the full text.
Phosphatases are famously hard to drug, so a glue that rebuilds a specific heterotrimer rather than inhibiting an active site is a smart route around that. Here the mutation defines both the patient population and the mechanism, a tidy match. I'd watch how selective it is among the many PP2A B-subunit complexes, since activating the wrong ones is the obvious tolerability worry.
Scaffold-hopped BCL6 PROTAC degrades its target in DLBCL cells and works orally in xenografts
- Scaffold hopping from the BCL6 ligand BI-3802 gave a new tricyclic oxazinoquinolinone binder.
- Linker and CRBN-recruiter tuning produced compound 15, a PROTAC that degraded BCL6 quickly and potently, in a CRBN- and proteasome-dependent way.
- It strongly suppressed BCL6-dependent DLBCL cell growth, and oral dosing inhibited tumor growth in an OCI-LY1 xenograft without evident toxicity.
BI-3802 is a polymerizing degrader with a peculiar mechanism, so a conventional CRBN-recruiting PROTAC from a fresh tricyclic core is a useful alternative route to BCL6 removal. Oral efficacy matters most here; I'd want to see how the molecule balances size and permeability, and whether degradation depth tracks with tumor response across non-OCI-LY1 lines.
Oral non-peptide STAT6 degrader WW-210 eases atopic dermatitis in mice
- Replaces the earlier phosphopeptide-based STAT6 PROTAC with non-peptide degraders designed for oral dosing.
- WW-210 degraded STAT6 at very low concentrations with a wide selectivity window over other STAT family members.
- It showed measurable oral bioavailability and degraded STAT6 in blood and spleen; in an atopic dermatitis mouse model it eased skin lesions, lowered serum IgE and reduced mast cell infiltration.
STAT6 is a transcription factor with a flat, polar SH2 surface, exactly the kind of target where inhibitors struggle and degraders can sidestep the problem. Getting oral exposure from a PROTAC that started life as a phosphopeptide is the real achievement; I'd like to see how molecular weight and polarity were managed, and whether the STAT-family selectivity holds in primary T cells.
Longer semi-rigid linkers drive VHL-based HDAC6 degraders with antileukemic activity
- A solid-phase route enabled systematic variation of VHL ligand, exit vector and linker in vorinostat-derived HDAC6 PROTACs.
- Longer, semi-rigid linkers gave the best degradation; the lead compounds degraded HDAC6 preferentially in MM.1S and MV4-11 cells.
- A matched non-degrading control with similar HDAC inhibition was clearly less antiproliferative, pointing to degradation itself as the driver.
The non-degrading control with matched enzyme inhibition is the kind of experiment that separates degradation from plain inhibition, and it favors the PROTAC. Preferential, not exclusive, HDAC6 selectivity from a vorinostat-like warhead is the weak point; a more isoform-selective ligand might sharpen it.
Ferulic acid-based PROTAC degrades TLR4 to protect endothelial cells
- Six PROTACs built on ferulic acid, a weakly active natural product, were tested for TLR4 degradation and migration in HUVECs.
- The lead, FP-4, degraded TLR4 and dampened TLR4/MyD88–NF-κB signaling plus TNF-α, ICAM-1 and VCAM-1 expression.
- Protection was also seen in zebrafish, extending PROTAC use beyond oncology.
Using a PROTAC to rescue a weak natural-product binder is clever, but TLR4 is a membrane receptor and the evidence here is thin on which E3 ligase is engaged and on ternary-complex dependence. I'd ask for rescue experiments with ligase and proteasome inhibitors before believing the mechanism.
DNMT1 PROTAC B7 blocks catalytic and scaffolding roles in liver fibrosis
- DNMT1 drives fibrogenesis through both catalytic and non-catalytic mechanisms, so the team built PROTAC degraders starting from DC-517 to hit both at once.
- Lead compound B7 mediates ubiquitin-proteasome degradation of DNMT1, lowers global DNA methylation and suppresses profibrotic responses in vitro.
- In vivo, B7 reduced DNMT1 levels and attenuated liver fibrosis, with less collagen deposition and better hepatic function.
DNMT1 is a textbook case for degrading rather than inhibiting, because an active-site inhibitor leaves the scaffolding role untouched. My worry is selectivity for liver and what removing an essential maintenance methyltransferase does in dividing tissue; fibrosis models are forgiving on both counts.
Roche signs molecular glue discovery deal with China's Defand Therapeutics
- STAT reports Roche has signed a drug discovery deal with Chinese biotech Defand Therapeutics focused on molecular glue medicines.
- Only the public lede of the STAT+ article could be read, so financial terms and targets are unverified here.
Roche keeps adding molecular glue partners rather than betting on one platform, and sourcing from Chinese biotechs fits the wider licensing trend. Without upfront and milestone figures I'd treat this as a discovery-stage option play, with the real signal being which targets and how many are named.
STAT+: Roche inks drug discovery deal with Chinese biotech, focused on molecular glue medicines ↗
Isoform-selective ULK1 PROTAC gives longer autophagy suppression than an inhibitor
- ATP-competitive inhibitors struggle to separate ULK1 from the near-identical ULK2, so the authors built cereblon-recruiting degraders instead.
- Structure-guided optimization gave MR-9036, which degrades ULK1 without touching ULK2 or IMiD neo-substrates, with ternary complex formation and proteasome dependence confirmed.
- After compound washout it kept autophagy suppressed longer than the clinical ULK1/2 inhibitor DCC-3116, with antitumor activity in KRAS G12C NSCLC models.
Selectivity between paralogs is where degraders can beat occupancy-driven drugs, and this is a clean example. What I'd check next is whether ULK2 compensation shows up in vivo, and whether washout durability holds in a model with realistic drug exposure rather than a pulse.
Lycia files for a $100M IPO to take its LYTAC degraders into allergy
- Lycia Therapeutics filed publicly for an IPO of up to $100M on Nasdaq under LYCA, after a confidential filing in July.
- Its LYTAC platform, from Carolyn Bertozzi's lab, shuttles extracellular proteins to the lysosome for degradation.
- Lead LCA-0061 degrades IgE for food allergy and is in Phase 1; LCA-0321 targets Graves' disease autoantibodies.
Early healthy-volunteer data showing a deep IgE drop give the story a clinical anchor, and an IPO is a useful test of public-market appetite for degraders outside oncology. The competition is formidable, though: omalizumab and its successors already own IgE, so Lycia must show a durable, differentiated edge.
Lycia seeks IPO for antibody degraders as TRexBio, Retension set terms ↗
A macrocyclic BI-4020-based PROTAC degrades C797S-resistant EGFR
- HQY1480 is a PROTAC built on the macrocyclic fourth-generation EGFR inhibitor BI-4020, with the linker and E3 ligand optimized systematically.
- It degraded several clinically relevant EGFR mutants at low nanomolar concentrations, and proteomics showed no detectable off-target degradation.
- It outperformed BI-4020 in xenografts, including osimertinib-resistant models, and degraded EGFR in patient-derived xenografts.
Starting from a macrocycle rather than a classical TKI is the smart move: it sidesteps the poor PK and selectivity that EGFR PROTACs usually inherit from their warheads. I'd want to see how the degrader holds up against compound-specific resistance mutations, and whether the favorable PK survives scale-up beyond mouse.
One atom flips a CRBN degrader from NSD2-selective to GSPT1-selective
- Starting from LLC0424, an NSD2 degrader that also engages GSPT1, a single-atom change gave two close analogues: 424-ND (NSD2-selective) and 424-GD (GSPT1-selective).
- 424-ND suppressed androgen receptor signaling in prostate cancer cells, while 424-GD triggered the integrated stress response.
- Biolayer interferometry showed distinct ternary-complex cooperativity for each target, and simulations suggested different low-energy conformations explain the bias.
Degrader selectivity here tracks ternary-complex cooperativity, not binary affinity, which is exactly what I'd want to see in an SAR table. A matched pair this tight is a ready-made probe set for NSD2 and GSPT1. I'd check proteome-wide selectivity and whether the cooperativity trend holds in cells.
Single-Atom Modification Enables Reversal of Degradation Selectivity between NSD2 and GSPT1 ↗
Oral isoindolinone GSPT1 glue degrader LG-NE-29 targets glioblastoma models
- A viability-based phenotypic screen flagged GSPT1 as a vulnerability in glioblastoma cells, where resistance to temozolomide arises quickly.
- Optimizing an isoindolinone series for metabolic stability gave LG-NE-29, a molecular glue that drives CRBN-dependent ubiquitination and proteasomal degradation of GSPT1.
- It is reported to avoid the metabolic weaknesses of earlier scaffolds, and to be orally bioavailable with activity in glioblastoma xenograft models.
Isoindolinone CRBN glues usually die on metabolism, so fixing that liability is the real story here. Before I believe it, I'd want the GSPT1 DC50/Dmax, proteome-wide selectivity (IKZF1/3, other neosubstrates), and oral PK with brain exposure. GSPT1 degradation is also broadly cytotoxic, so the therapeutic window in normal cells matters.
DNA origami carrying a barnase variant is built to cleave mutant KRAS mRNA
- Mutant KRAS variants are structurally diverse and lack druggable pockets, which has limited small-molecule inhibitors.
- The authors assemble a degrader on a six-helix-bundle DNA origami scaffold that targets the mRNA rather than the protein.
- One module pairs an engineered barnase variant with a programmable recognition strand, cutting RNA directly without relying on endogenous cellular machinery; a second module is designed for cell penetration.
If KRAS has no pocket worth chasing, going after the mRNA is a fair dodge, and a catalytic barnase gives a clean mechanism: sequence-guided cleavage, no reliance on endogenous machinery. But I would want to see the data before getting excited. How well does the recognition strand discriminate single-base mutants from wild-type KRAS, given barnase's cleavage is catalytic and unforgiving of leakage? And does it survive delivery, with real potency in cells and a sensible comparison to siRNA or ASO?
Can ternary-complex scoring rank close PROTAC linker analogues? A matched-pose test
- Linker optimization in targeted protein degradation is still largely empirical.
- The preprint asks whether current computational methods can rank close linker analogues before synthesis, the finest chemical differences yet tested.
- It uses a matched-pose design on VHL-recruiting SHP2 degraders to isolate the effect of the linker.
- This is a preprint, not yet peer reviewed; the snippet-level abstract available limits detail on the outcome.
Linker tweaks are where PROTAC campaigns burn months of synthesis, so an honest test of whether scoring can separate near-identical analogues is more useful than another headline-grabbing benchmark. Matched poses remove the usual excuse that the method just got the geometry wrong. Even a negative answer helps: it tells us to keep building degradation and cooperativity assays rather than trusting a docked score.
Bispecific GTACs antagonize GPCRs by sending them to the lysosome
- GPCR–TfR1 targeting chimeras (GTACs) are bispecific antibodies that pair a receptor binder with a transferrin-receptor binder.
- They drive endocytosis and lysosomal degradation of the GPCR, rather than blocking the orthosteric site.
- Reported for BILF1, RXFP1 and CCR6, covering viral, cancer and immune targets that are hard to drug.
- Signalling, including constitutive activity, was fully shut down, with markedly greater potency than conventional antibody antagonists.
Degrading the receptor sidesteps the usual GPCR headache of finding a clean orthosteric or allosteric small molecule, and it kills constitutive signalling that inverse agonists only partly touch. The catch for my own work: it is an antibody format, so oral exposure and tissue reach are off the table, and TfR1 recruitment brings its own distribution and safety questions. Still, it hands us a genuine alternative mechanism for orphan-like GPCRs where chemistry has stalled.
GPCR antagonism via rewiring of receptor trafficking and degradation ↗
Bifunctional OGTACs steer OGT to install O-GlcNAc on chosen proteins
- OGT/OGA inhibition affects thousands of substrates, so protein-specific O-GlcNAc functions are hard to assign; OGTACs address this by recruiting OGT to a chosen protein.
- Each OGTAC joins an OGT-engaging element, a linker and a target-recognition motif, and can partly bypass TPR-domain substrate recognition.
- Productive O-GlcNAc writing needs proper ternary-complex formation and noninhibitory OGT binding, while the target-recognition motif sets targetable scope and selectivity.
- Local installation is linked to changes in protein turnover, signaling and transcription.
The OGT-binding warhead is the make-or-break piece here: if it inhibits OGT, you lose the very activity you're trying to redirect, so noninhibitory binders are the real SAR hurdle, much as with E3 ligands in degraders. I also like that the target-recognition motif, not OGT's TPR domain, sets selectivity, which makes this modular. It's an Accounts-level overview, so I'd want to see how well the chimeras hold up across targets before getting excited.
Chemically Induced Proximity for Targeted Protein O-GlcNAcylation ↗
Scope library: a chemical space between fragments and full molecules for tractable hits
- Scope defines a chemical space between fragments and elaborated low-molecular-weight library compounds, emphasizing compound quality, ligand efficiency and selected property ranges to keep hits tractable for medicinal chemistry.
- Scope ring systems (ring-X-ring) organize the space and guide intentional functionalization toward low- to mid-micromolar potency; a roughly 10k-compound set suits medium-throughput SPR, native MS, DSF and biochemical screens.
- Case studies on trypanosomal CLK1, a 14-3-3/ERα molecular glue project and SARS-CoV-2 Mpro show comparable primary hit rates to diversity sets, with better ligand efficiency after counter-screening.
Honestly, the pitch I like here is hits you can actually start working on: a library sitting between fragments and full-size compounds, built around ligand efficiency, with ring-X-ring cores that tell you where to functionalize next. A 10k set fits SPR, native MS and DSF, so a smaller group can run it. The open question is whether primary hit rates on par with diversity sets, with better LE after counter-screening, hold up beyond three targets, and how much the scaffold constraint narrows novelty.
Native MS Shows PROTAC Linker Length and Warhead Identity Shape Ternary Complexes Differently
- Ion mobility, surface-induced dissociation and variable-temperature ESI were combined to probe BRD4–PROTAC–VCB complexes built with two BET ligands (JQ1 and I-BET726) and PEG linkers of different lengths.
- Shorter linkers held complexes in more extended shapes; longer, flexible linkers allowed relaxed, native-like conformations.
- JQ1 complexes tended to eject the PROTAC under collision, while tighter-binding I-BET726 complexes retained it; the two also melted differently.
Linker optimization is still mostly empirical, so orthogonal readouts of how architecture shapes the complex interface are welcome. Gas-phase data are not solution cooperativity, and I'd not rank degraders by them alone, but pairing them with cellular degradation could help rationalize why two warheads behave so differently. A preprint, so treat the conclusions as provisional until peer review.
p300/CBP Drug Discovery: Do Bifunctional Degraders Now Beat Classical Inhibitors?
- A perspective reviewing small-molecule inhibitors of the p300/CBP bromodomain and catalytic (HAT) domain, with emphasis on how the leading clinical compounds were optimized.
- It then follows the field's shift toward bifunctional proximity-inducing molecules, including PROTAC degraders.
- The article compares what each modality offers for these large, multidomain coactivators.
p300/CBP is a good test of when degradation earns its molecular weight: scaffolding functions that inhibitors leave intact are exactly what a degrader removes. The HAT-domain and bromodomain optimization stories are useful reading for anyone with a stubborn chromatin target. I'd read the degrader sections skeptically on paralog selectivity, since p300 and CBP are nearly identical.
A '2-in-1' PROTAC Folds the Cereblon Ligand into the HDAC8 Cap to Shrink the Degrader
- Instead of tethering two ligands, the cereblon-binding motif is built into the capping group of an HDAC8 inhibitor, so one structural element engages both proteins.
- Versus the group's first-generation degrader, the compact analogs are smaller, more selective and more drug-like.
- They degrade HDAC8 potently in vivo.
Most of us accept PROTAC bulk as a tax; fusing the E3 ligand into the warhead's cap group attacks that directly and is a transferable idea for other zinc-enzyme targets. The question I'd press is whether the shared motif compromises either binding event or cereblon neosubstrate selectivity. If in vivo degradation holds with better properties, the 'linkerless' direction deserves more attention.
A 2-in-1 Strategy for the Discovery of Compact HDAC8 Protac Degraders ↗
BmTACs Ride Age-Upregulated Transcytosis to Deliver a ROS-Activated DAPK1 Degrader into the Brain
- Brain delivery is the main barrier for degraders in neurodegeneration; BmTACs attach a macrocyclic peptide shuttle that exploits caveolae-mediated transcytosis, which rises with age in brain endothelium.
- A reactive-oxygen-species-responsive cage on the VHL ligand keeps the PROTAC inactive until it reaches high-ROS tissue.
- The platform is designed to remove activated DAPK1 selectively in the aging brain.
Two gating layers, shuttle for entry and ROS cage for activation, is clever systems design, but it moves the problem from medicinal chemistry to conjugate CMC and PK. I'd look hard at the unmasked-PROTAC fraction in periphery and at the shuttle's dependence on aged-endothelium biology, which could narrow the patient window. A real step for CNS degraders if the in vivo data hold up.
Three Chemoselective Routes Turn Cereblon PROTACs into Cleavable Prodrugs
- Cereblon-recruiting PROTACs are hard to derivatize for prodrug delivery; the paper offers three orthogonal handles: triazole quaternization, tertiary-amine alkylation and a hydroxyl linker.
- The approaches give cleavable prodrugs with tunable release kinetics, compatible with PEGylated constructs and bottlebrush prodrugs.
- Representative examples showed controlled degrader release, in vitro anticancer activity, tumor accumulation and preliminary in vivo efficacy.
The real PROTAC problem is exposure rather than ternary-complex cooperativity, so a modular way to mask and release them is overdue. Chemoselectivity on a glutarimide-bearing molecule is the practical point: if it works on existing degraders without re-optimization, it is genuinely reusable. I'd check release in plasma versus tumor, and whether the masked forms avoid premature cereblon engagement.
Generalizable Strategies for the Synthesis of Cereblon-Recruiting PROTAC Prodrugs ↗
Merck Licenses China-Origin KRAS G12D Inhibitor SPR2015 for $400M Upfront
- Merck & Co. entered an exclusive global license agreement with Shanghai-based SciBrunch Therapeutics for SPR2015, an investigational oral KRAS G12D molecular-glue inhibitor.
- SciBrunch will receive $400 million upfront, with total deal value up to $2.13 billion including milestone payments.
- The deal reflects a growing trend of U.S. pharma companies in-licensing China-originated oncology assets.
This plugs Merck's biggest KRAS gap: everyone's crowded into G12C, but G12D — more common in pancreatic and colorectal cancer — has stayed stubbornly undrugged with covalent chemistry. A molecular-glue approach, if it works, sidesteps that entirely. The modest 19% upfront-to-total ratio signals early-stage derisking, not a validated asset — expect Western rivals to scramble for the remaining China-origin G12D candidates.
Fluorine Tweaks to Lipid Nanoparticles Boost PROTAC Delivery Efficiency
- Researchers built ionizable lipid nanoparticles with fluorinated lipid tails to encapsulate and deliver a PROTAC degrader payload.
- Tuning the degree of fluorination altered nanoparticle physicochemical properties and redirected intracellular trafficking, promoting more efficient endosomal escape into the cytosol.
- Optimized fluorinated formulations achieved greater cytosolic PROTAC release and stronger target-protein degradation than non-fluorinated lipid controls.
Most LNP-delivered PROTAC payload never escapes the endosome — it gets trapped and degraded lysosomally, so tuning fluorine content on the lipid tail to boost cytosolic release is a smart lever, borrowed straight from siRNA-LNP playbooks. If this scaffold generalizes beyond whichever degrader they tested, it could rescue plenty of otherwise-undruggable bifunctional PROTACs too big or polar for oral dosing.
Oral PROTAC Degrader Targets STAT6 in Atopic Dermatitis
- A new PROTAC degrader targets STAT6, the transcription factor that carries IL-4/IL-13 signals driving Th2-type allergic inflammation.
- Instead of inhibiting STAT6, the molecule links a STAT6-binding fragment to a degradation handle for potency and selectivity over related STAT proteins.
- It reportedly showed oral efficacy in preclinical models, pointing to a pill-based alternative to injectable biologics for atopic dermatitis.
Oral bioavailability is the harder win here than target choice — PROTACs routinely blow past Lipinski/bRo5 limits (MW, PSA), so a gut-stable, orally efficacious degrader is the rarer synthetic feat. If STAT1/3/5 selectivity holds up in vivo, this leapfrogs injectable dupilumab and pressures other oral STAT6 degrader programs already in the clinic.