Infectious disease
34 articles
GSK wins FDA approval for its hepatitis B drug
- STAT reports that GSK has won FDA approval for its hepatitis B drug.
- The drug extended functional cures to far more patients than previous methods, according to the report.
- Details beyond the headline were not available to us; the product is understood to be the antisense bepirovirsen.
A functional-cure label in hepatitis B is a landmark for the field, and GSK gets it with an antisense oligo, not a small molecule or antibody. The commercial question is uptake: finite treatment courses mean less recurring revenue per patient, but a large, long-diagnosed population. Watch Vir, Arbutus and the Chinese siRNA players, who now have a bar to clear.
Roivant reports positive trial results in non-infectious uveitis
- STAT reports that Roivant announced positive trial results for its immune drug in non-infectious uveitis.
- The result could open a new market for the drug beyond its current indications.
- Only the headline and lede were available to us; the specific endpoints and data are not confirmed here.
Uveitis is a small but sticky indication where a non-steroid oral option is valued, and another label extension spreads development cost across more indications. The market will want to see the effect size against the standard of care, not just the win itself. I'd expect this to feed straight into Roivant's partnering and financing narrative for the asset.
STAT+: Roivant says closely watched immune drug succeeded in new eye disease ↗
A pyrazine-2-carboxamide antimalarial that cures mice in one dose has entered phase 1
- A P. falciparum growth-inhibition screen identified a new pyrazine-2-carboxamide series for blood-stage malaria.
- Lead optimization improved anti-plasmodial potency and metabolic stability and reduced CYP2D6 inhibition risk, giving IWY357.
- A single dose was fully curative in a Pf-humanized SCID mouse model, resistance selection showed a high barrier, and the compound has progressed through GLP toxicology into phase 1.
A phenotypic hit taken all the way to the clinic with a single-dose cure in the humanized-mouse model is what the field has wanted since resistance to front-line agents began eroding. The CYP2D6 fix matters for combinations, which is where a short-course regimen would actually live. I would watch the human PK, since a single-dose claim lives or dies on exposure.
Epoxysuccinamide warheads hit SARS-CoV-2 PLpro hard, but a hydrazide linker undermines them
- Covalent PLpro inhibitors were designed by combining an epoxysuccinamide warhead for Cys-111 with groove-binding features borrowed from non-covalent inhibitors.
- The compounds showed very high enzymatic potency and strongly reduced viral titres in cell culture.
- The flexible hydrazide linker was cleaved by hepatic carboxylesterases, and alternative linkers did not work, so the series is metabolically limited.
A potent warhead that dies in the liver is a familiar story, and here the culprit is the very linker the chemistry needs for Cys-111 reach. I'd still keep the epoxysuccinamide in the toolbox for the next coronavirus, but the linker would be the first thing I'd redesign.
Discovery of Epoxysuccinates as Potent Covalent Inhibitors of SARS-CoV-2 Papain-like Protease ↗
3H-1,5-benzodiazepines show micromolar antimalarial activity; PfSET3 floated as target
- Eighteen new 3H-1,5-benzodiazepines were made and tested against chloroquine-sensitive and resistant P. falciparum strains, with HepG2 cytotoxicity as a first selectivity check.
- Several compounds were active in the low micromolar range, with different members showing the best potency and the best selectivity.
- The two leads were only weak inhibitors of human G9a; docking, MM-GBSA and MD were used to propose binding to parasite PfSET3.
Low-micromolar whole-cell activity with a thin selectivity window is a start, not a lead; the target claim rests on docking, which I'd treat as a hypothesis only. What I like is the unusual chemotype against a parasite epigenetic enzyme. Next I'd want a biochemical PfSET3 assay and some SAR around the best-selectivity compound.
Optimised benzothiophenes block Mtb virulence by inhibiting the MprB histidine kinase
- The earlier hit BTP15 protects host cells from Mtb-induced death by blocking phagosomal escape through MprB inhibition, but had poor pharmacokinetics.
- New benzothiophene analogues were screened for MprB inhibition, microsomal stability, toxicity and ex vivo efficacy in THP-1 and MRC-5 cells.
- The aim is a virulence-blocking route that avoids killing the bacterium directly, which may reduce resistance pressure.
Antivirulence is attractive on paper, but the hard part is demonstrating efficacy without a bactericidal readout. I'd look hardest at whether the stability gains translate into in vivo exposure, since BTP15's problem was PK, and at whether MprB engagement is shown cleanly in the infected-cell setting.
PDIA3 inhibitors from an N-hydroxyindole series act as host-targeted antivirals against respiratory viruses
- PDIA3, an ER oxidoreductase involved in folding glycosylated viral envelope proteins, is an underexplored host target for antivirals.
- A new N-hydroxyindole-2-carboxamide class, exemplified by AV22, inhibits PDIA3 and shows broad activity against major human respiratory viruses.
- In coronavirus-infected cells AV22 raised release of non-infectious particles and reduced disulfide bond formation in spike.
Host-directed antivirals dodge resistance but live or die on the therapeutic window, because PDIA3 does real work in uninfected cells. An N-hydroxy group is also a flag for me: metal binding and metabolic liability can both bite. I'd look first at cytotoxicity margins and microsomal stability.
First thiazolamide PI4KIIIβ/HDAC dual inhibitors take a host-directed route against HCV
- Host-directed dual inhibition of PI4KIIIβ and HDACs had not previously been reported for hepatitis C, where resistance to direct-acting antivirals remains a concern.
- A series of thiazolamide-based dual inhibitors was designed, synthesised and evaluated.
- Lead compounds showed potent enzymatic inhibition of both targets together with anti-HCV activity.
With DAAs curing most patients, the case for a host-directed HCV drug is hard to make commercially, and a dual PI4KIIIβ/HDAC profile adds tox risk. I read this as a good exercise in multitarget design, but would want to see cytotoxicity and kinase selectivity before calling the window real.
Bis-catecholate siderophore carries ampicillin into resistant Pseudomonas
- A Trojan-horse design hijacks bacterial iron uptake to move a β-lactam payload across the Gram-negative outer membrane.
- Ampicillin was conjugated to mono-catecholate, bis-catecholate and catecholate–hydroxamate siderophores and the series compared.
- The bis-catecholate conjugate is reported as the selective one, extending ampicillin's reach to multidrug-resistant P. aeruginosa.
Getting an old penicillin to work on Pseudomonas by changing only the delivery vector is a clean demonstration of the siderophore approach. Linker stability in serum and the chance that resistant strains simply down-regulate the uptake receptors are the things I'd check next.
Kinetic target-guided synthesis yields potent hydroxamate LasB inhibitors
- Guided by earlier crystal structures, kinetic target-guided synthesis was used to assemble inhibitors of the P. aeruginosa virulence factor elastase LasB.
- Extensive SAR gave hydroxamic acid inhibitors with very high potency and good selectivity over a panel of human off-targets.
- The compounds protected lung epithelial cells from LasB damage, showed in vivo efficacy, and reached lung exposure above their biochemical potency.
Using the enzyme itself to pick its best fragment pairs is a smart way into a metalloprotease pocket, and the lung PK above IC50 is exactly the data antivirulence programs usually lack. Hydroxamates still carry metabolic and zinc-binding baggage, so the off-target panel on other metalloenzymes is where I'd look first.
Pose prediction plateaus after about five crystal structures per scaffold
- Using 403 SARS-CoV-2 main protease structures from the open COVID Moonshot campaign, the authors asked how many new crystal structures are worth collecting.
- Similar reference ligands give the best pose prediction, and success plateaus at roughly five structures per Bemis-Murcko scaffold, exceeding 95% for the lead series.
This gives structural biology a concrete budget line: after about five structures per scaffold, the next soak buys little for pose prediction. Caveat: Mpro is a rigid, well-behaved pocket, so I'd not carry that number over to flexible kinases or induced-fit targets.
How Many Crystal Structures Do You Need to Trust Your Docking Results? ↗
Sulfonium-modified pneumocandins overcome Cryptococcus' intrinsic echinocandin resistance
- Covalent sulfonium modification of the natural pneumocandin B0 scaffold gave derivatives active against Candida and able to reverse innate Cryptococcus neoformans resistance (MIC as low as 2 μg/mL).
- The modification raised fungal membrane permeability and caused depolarization while strengthening glucan synthase inhibition.
- Leads 3h and 5h showed low resistance potential, good safety and PK, and in vivo antifungal efficacy.
Echinocandins have never covered Cryptococcus, so adding a membrane-active cationic handle to restore activity is a smart reuse of a validated scaffold. The risk is that membrane disruption narrows the selectivity window, so host-cell toxicity data and the mechanism split deserve a close read.
Modeling-led design yields a pan-serotype dengue NS4B inhibitor candidate
- Comparative models of the structurally unresolved NS4B across all four dengue serotypes reveal a conserved transmembrane pocket that fits known resistance mutations.
- Docking of the JNJ-series inhibitors fed predictive field-based 3D-QSAR models, which were used to screen bioisosteres and in-house compounds.
- The top candidate, BNJ-495, was extremely potent against serotype 2 with a high selectivity index, and its conserved binding contacts suggest broad-spectrum activity.
A homology-model plus 3D-QSAR workflow that delivers a prospectively validated hit against a membrane protein with no structure is rare, and that is what makes this worth a look. Before I trust 'pan-serotype', I'd want to see the other three serotypes tested and whether the JNJ-series liabilities carried over.
Structure-Guided Design of a Subnanomolar Dengue Virus NS4B Inhibitor ↗
Entrance-channel design tames cytotoxicity of the JK-4b NNRTI lead
- JK-4b, a potent NNRTI active against wild-type and clinical HIV-1 variants, was shelved because of high cytotoxicity; the authors used it as a lead for new analogues.
- Structure-guided designs addressing the NNRTI entrance channel gave a series with lower cytotoxicity and improved selectivity.
- Lead compound 9n retained strong potency against common resistance mutants, including double mutants, at levels comparable to etravirine.
- 9n also showed minimal cytochrome P450 inhibition and good human liver microsome stability, supporting further development.
Rescuing a shelved lead is always more interesting than starting cold: JK-4b already had the potency and resistance coverage, so the real question was whether entrance-channel contacts could decouple that from its cytotoxicity. If 9n's profile holds up, that suggests the toxicity was scaffold-tunable, not baked into the pharmacophore. Matching etravirine on double mutants while staying clean on P450 and microsome stability is what I'd want to see before making more.
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.
Merck Pulls Recarbrio From the U.S. Market, Leaving No Late-Stage Antibacterial Programs
- Merck is discontinuing Recarbrio, its reserve-use antibiotic combination, in the U.S. as part of a portfolio review, and says the move is unrelated to safety or quality.
- Approved seven years ago for hospital-acquired pneumonia and complicated urinary and abdominal infections with few options, it leaves Merck with only mature antibiotics and, per trade reports, no antibacterial programs in Phase II or later.
Reserve antibiotics are meant to be used sparingly, which caps sales, and a big pharma walking away from one confirms the broken economics of anti-infective launches. Small biotechs will read this as a warning, and policymakers will cite it in the case for pull incentives. The open question is whether Merck out-licenses the product or simply sunsets it.
Merck discontinues a crucial antibiotic despite concerns over superbug resistance ↗
Repeating a Five-Residue Melittin Fragment Gives Non-Haemolytic β-Sheet Antibacterial Peptides
- Melittin is potently antimicrobial but too haemolytic to be a lead; the authors built 10-, 15- and 20-mer peptides from repeats of its C-terminal WIKRK segment.
- The 15- and 20-mers adopt β-sheet structure in bacterial-mimetic vesicles, with negligible haemolysis and cytotoxicity and strong activity against bacteria and mycobacteria.
- They were active in an E. coli mouse infection model by intravenous dosing and inhibited transcription and translation, suggesting an intracellular mechanism.
Shrinking melittin to a tandem repeat and flipping it from helix to sheet is a neat way to decouple killing from lysis. The intracellular mode of action is the interesting part, since it points away from the membrane-disruption liabilities that kill most AMPs in the clinic. I'd still want protease stability and plasma binding data before believing the in vivo window.
Mirum’s Brelovitug Hits Phase 3 Primary Endpoint in Hepatitis Delta
- The Phase 3 portion of AZURE-1 met its primary endpoint at week 24: roughly half of treated patients responded on either the weekly or four-weekly subcutaneous regimen, versus none on delayed treatment.
- No grade 3 or higher or serious adverse events were reported through week 24. A second Phase 3, AZURE-4, is expected in Q4, with a filing possible in the first half of next year.
Mirum now has a credible, differentiated challenger in hepatitis delta, with a monthly-dosing option that Gilead's and Vir's programs will have to answer commercially. But the depth-of-suppression numbers are modest, so the AZURE-4 readout matters more than today's headline. For an acquired asset, a clean first Phase 3 also validates the deal thesis and de-risks Mirum's rare-liver pipeline story.
Mirum posts phase 3 hepatitis win for 'commercially different… ↗
Siderophore Vectors Smuggle Meropenem and an MBL Inhibitor into Resistant Pseudomonas
- Tris-catecholate siderophore–meropenem conjugates overcame porin-loss and efflux-based carbapenem resistance in P. aeruginosa in an iron-dependent manner.
- The team also vectorized an indole-carboxylate MBL inhibitor, which alone barely works in P. aeruginosa, apparently for permeability reasons.
- The conjugates restored inhibitor activity and reversed meropenem and cefiderocol resistance in MBL-producing clinical isolates, in vitro and in a Galleria mellonella model.
Permeability, not target affinity, is what kills most Gram-negative programs, so vectorizing a known but impermeable MBL inhibitor is a smart shortcut. Reversing cefiderocol resistance is the headline for me, since that drug already exploits iron uptake. I'd press on conjugate stability in serum and whether resistance simply migrates to siderophore receptors.
LSD1 Inhibition May Modulate Response to Nucleoside Analogue Therapies
- Perspective-style article proposing that pharmacological inhibition of the epigenetic enzyme LSD1 (KDM1A) can modulate cellular sensitivity to nucleoside analogue therapeutics.
- Synthesizes evidence across myeloid malignancies and viral infections, two disease areas where nucleoside analogues are already established treatments.
- Argues LSD1-driven chromatin and transcriptional changes may underlie altered drug response, positioning LSD1 inhibitors as potential combination partners to enhance nucleoside analogue efficacy across both fields.
What grabs me is that clinical-stage LSD1 chemotypes already exist (bomedemstat, seclidemstat, and friends) — if the chromatin argument holds up, repurposing into combo trials is cheap and fast. But this is a Perspective stitching two literatures together, not new data; before I'd trust a DDI-manageable combo across both AML and antivirals, I want real mechanistic proof that LSD1 inhibition actually changes nucleoside analogue uptake/incorporation, not just correlation.
New PET Probe Exploits Iron-MurB Interaction to Image Bacterial Infections
- Iron-binding chemistry anchors a new bacteria-targeted imaging probe engaging MurB, an enzyme unique to bacterial peptidoglycan (cell-wall) biosynthesis, for radiolabeling.
- The probe is proposed as a platform for PET (positron emission tomography), aiming to visualize actual bacterial infection sites in vivo rather than relying on nonspecific inflammation markers.
- By targeting a pathway absent in human cells, the approach could help clinicians distinguish genuine bacterial infection from sterile inflammation, addressing a longstanding gap in infectious-disease imaging.
MurB being absent in human cells is about as clean a selectivity handle as probe chemistry gets, aimed at a real gap — FDG-PET can't tell infection from sterile inflammation. The iron-chelating warhead is a neat trick too: swap in a radiometal and the labeling chemistry comes free. Makes you wonder if that MurB-binding core doubles as an antibacterial lead.
A Smarter Sugar Anchor Sharpens a Phage-Based Cancer Vaccine
- Chemists built fluorinated Tn-antigen mimics using a tyrosine-linked GalNAc (Tyr-GalNAc) instead of the natural serine/threonine attachment, then conjugated them to bacteriophage Qβ virus-like particles.
- Qβ is a multivalent carrier platform known for driving strong antibody responses to small carbohydrate tumor antigens.
- The fluorinated Tyr-GalNAc-Qβ conjugates showed potent antitumor activity in preclinical models, adding to evidence that targeted fluorination can boost carbohydrate-antigen vaccine immunogenicity.
Tn's Achilles' heel has always been the native GalNAc-α-O-Ser/Thr linkage: glycosidase-labile and a weak, self-like hapten that struggles to break B-cell tolerance. Rerouting to a Tyr-aryl glycoside dodges the enzymes evolved for O-Ser/Thr GalNAc, and fluorination looks like classic conformational/electronic tuning to sharpen epitope recognition. Neither move touches the target — it's synthetic hapten engineering, with Qβ's ~180-copy multivalent display doing the real work of forcing an antibody response.
Roche Flu Drug Xofluza Cleared for Generic Production Under Pandemic-Prep Deal
- The Medicines Patent Pool signed sub-licensing deals with 11 generic manufacturers to produce Roche's flu antiviral Xofluza (baloxavir marboxil).
- The agreements, building on MPP's broader license with Roche, cover supply to roughly 129 low- and middle-income countries and include technical support for regulatory approval.
- They also carry pandemic-specific provisions meant to ease supply, territory and royalty constraints if a global flu outbreak occurs.
Roche is front-running compulsory-licensing pressure here, not waiting for a pandemic to force its hand the way COVID access fights forced others — cheap reputational insurance bought years early. But 11 sub-licensees on paper isn't surge capacity: without tech-transfer and validation runs now, that capacity stays theoretical until an outbreak tests it. Still, MPP's Xofluza network beats what Gilead ever built for oseltamivir — a real bar-raise on pandemic-prep licensing.
Licensing deals on generic versions of Roche flu drug aimed at preparing for pandemic ↗
TrmD as an Antibacterial Target: A Review of Small-Molecule Inhibitor Discovery Strategies
- TrmD, a SPOUT-family bacterial tRNA methyltransferase without a human counterpart, is highlighted as a validated antibacterial target amid rising antimicrobial resistance.
- The review catalogs strategies used to discover small-molecule TrmD inhibitors—fragment-based design, high-throughput and virtual screening, click-chemistry-enabled direct-to-biology methods, molecular hybridization, and prodrug approaches.
- It synthesizes structural features and structure-activity relationships across these diverse chemical scaffolds to inform future inhibitor optimization.
TrmD's lack of a human ortholog is the real selling point here — a wide therapeutic window without the usual off-target liability, which is rare enough in antibacterial discovery to justify the review's existence. The click-chemistry/direct-to-biology entries jump out as the underexploited lane: fast SAR turnaround without carrying every analog through full synthesis, exactly what a fragmented, scaffold-diverse target like this needs before someone finally nails spectrum and PK.
TrmD: A Promising Antibacterial Target and Its Small-Molecule Inhibitors ↗
Antibody-Inspired Peptides Take Aim at Flu's Fusion Machinery
- Applies a hotspot-centric computational design strategy, grafting key antibody-binding side chains onto small L-peptide scaffolds that mimic how neutralizing antibodies engage influenza hemagglutinin.
- Draws design cues from the antigen-binding interfaces of broadly neutralizing antibodies FI6v3 and CR9114, both directed at the hemagglutinin stem.
- Aims to yield peptides that block the hemagglutinin conformational change driving membrane fusion, offering a structure-guided route to antibody-inspired flu therapeutics.
FI6v3 and CR9114 are smart hotspots to steal from, and a compact L-peptide is far more tractable to make and dose than the antibody it's mimicking. But stem-directed HA binders have a rough history against escape mutants — durability of coverage across drift, not just initial fusion-blocking potency, is the question I'd want answered before getting excited about a therapeutic path.
Antibody Hotspot-Centric de Novo Design of Peptide Inhibitors of Influenza A Virus Membrane Fusion ↗
AI-Guided Optimization Yields a Potent New HBV Capsid Assembly Modulator
- Starts from known capsid assembly modulator NVR 3-778 and applies a multi-objective optimization workflow combining structure-based fragment growing with medicinal chemistry.
- Machine-learning models are used alongside traditional design to jointly predict antiviral activity and drug-like/ADMET properties.
- The workflow generated and evaluated roughly four dozen novel sulfamoylbenzamide analogs.
- Lead compound 11B-6 emerged with superior antiviral potency and improved drug-like properties versus the starting scaffold.
Forty-some analogs to land one clearly superior lead is a tight design-make-test cycle, and coupling ML-based ADMET prediction to fragment growing off NVR 3-778 is exactly where these models earn their keep — multi-parameter optimization, not potency-chasing alone. Next question: does 11B-6 hold up against the CAM-resistant HBV variants that have dogged this chemotype before.
AI-Driven Lead Optimization Delivers 11B-6, a More Potent HBV Capsid Modulator
- Investigators describe a multi-objective lead-optimization campaign built on the sulfamoylbenzamide (SBA) chemotype exemplified by NVR 3-778, an earlier clinical-stage HBV capsid assembly modulator (CAM).
- An AI-guided computational workflow was integrated with iterative synthesis to simultaneously optimize antiviral potency alongside physicochemical and ADME/drug-like properties across the series.
- The campaign identified 11B-6 as the optimized lead, reported to combine stronger anti-HBV potency with improved drug-like characteristics relative to earlier series analogues.
- Mechanistically, 11B-6 functions as a capsid assembly modulator, engaging the HBV core (capsid) protein to misdirect nucleocapsid assembly and interfere with viral replication.
- The work positions 11B-6 as a candidate for further preclinical evaluation within the sulfamoylbenzamide CAM class for chronic hepatitis B treatment.
What actually catches my eye isn't the potency bump — it's that AI-guided optimization was wired into the synthesis loop, not run as a pre-filter before chemists took over. That's the difference between a screening deck and a real DMTA cycle. Going back to the SBA/NVR 3-778 chemotype rather than hunting a new capsid-binding scaffold is the pragmatic call: the pocket and assembly-misdirection mechanism are already de-risked clinically, so this campaign is buying SAR knowledge instead of paying discovery tax twice. That said, 'improved drug-like properties' is a claim I want backed by real microsomal stability, plasma protein binding, and hERG numbers before I get excited — potency plus a nicer cLogP on paper doesn't guarantee 11B-6 clears whatever tolerability hurdle likely sank NVR 3-778. Worth watching, not yet worth celebrating.
New "Scope" Chemical Space Yields Ligand-Efficient Hits Across Three Targets
- "Scope" describes a mid-sized (10k-50k compound) chemical space positioned between minimal fragments and fully elaborated low-molecular-weight libraries, designed to maximize ligand efficiency and medicinal chemistry tractability.
- The authors introduce "Scope ring systems" (ring-X-ring) as a core organizing concept for building libraries and guiding functionalization toward sufficient potency.
- A 10k-compound Scope screening set — evaluated by SPR, native mass spectrometry, DSF, and biochemical assays — matches general diversity sets' primary hit rates even at higher screening concentrations, while showing superior ligand efficiency and higher hit rates after counter-screening.
- Case studies on trypanosomal CLK1 kinase, a 14-3-3/estrogen receptor-alpha molecular glue project, and SARS-CoV-2 main protease show the set yields diverse, tractable, ligand-efficient hits across varied binding sites.
The "sweet spot between fragments and full libraries" pitch isn't new — DEL, FBDD, and house libraries have all claimed it before. What's actually new in Scope is the ring-X-ring organizing logic: forcing vectors off two ring systems rather than one flat scaffold gives a built-in growth vector for SAR from hit one, the part fragment campaigns usually bolt on later. The number that matters to me isn't the hit rate, it's "higher hit rate after counter-screening" — that's fewer SPR artifacts and aggregators wasting my week. The real test is the 14-3-3/ERα glue case: PPI/glue targets chew up conventional libraries because there's no deep pocket to reward LE. If a rigid, moderately-sized scaffold set can seed a glue hit, that's the transferability claim worth watching, not the Mpro or CLK1 wins.
Re-Engineering a Toxic HIV Inhibitor into a Safer Lead
- Starting from JK-4b, a potent but overly cytotoxic non-nucleoside reverse transcriptase inhibitor (NNRTI), researchers pursued structure-guided optimization to fix its safety liability.
- Design efforts targeted the NNRTI entrance channel, a sub-pocket near the classical allosteric site, to reshape how analogs bind reverse transcriptase and reduce off-target toxicity.
- Structure-activity relationship (SAR) studies across this new series pointed to compound 9n as the standout, with markedly improved selectivity and much lower cytotoxicity than JK-4b.
- Despite the safety redesign, 9n kept potent antiviral activity against both wild-type HIV-1 and clinically relevant drug-resistant variants, preserving the lead's core strength.
- The work illustrates entrance-channel-focused chemistry as a practical strategy for detoxifying promising but toxicity-limited NNRTI candidates.
This mechanism is what caught my eye: if cytotoxicity in JK-4b traced to deep induced-fit distortion in the classical pocket, moving the pharmacophore to a shallower, more solvent-exposed sub-pocket is a clean way to keep the RT H-bond network while shedding the strain that drives off-target hits. Retained potency against resistant variants is the real tell — K103N/Y181C-type mutations cluster in the classical pocket, so if 9n still works, its binding mode isn't leaning on that contact set, which also argues the toxicity really was off-target, not a right-target dose-limiting problem. Practically, a solvent-facing channel is easier SAR real estate — more room to tune logP/solubility without wrecking the core pharmacophore, so this reads generalizable, not a one-off rescue. Prefer this over the usual toxicity fixes (metabolite masking, prodrugging) — it's addressing binding geometry, not just downstream liability.
The Hidden Loop Guiding Malaria Invasion
- This is a perspective/analysis article, not a new experimental study, focused on Plasmodium falciparum apical membrane antigen 1 (PfAMA1) as an anti-malarial drug target.
- PfAMA1 binds rhoptry neck protein 2 (PfRON2) to form the moving junction that enables the malaria parasite to invade red blood cells, making this protein-protein interaction a key therapeutic target.
- Most structure-based inhibitor design has targeted the hydrophobic trough, a well-defined groove on PfAMA1 that accommodates the PfRON2 peptide.
- The authors highlight a domain 2 (D2) loop near the trough that shows cryptic, conformation-dependent dynamics rather than a fixed structure.
- They argue this loop flexibility, previously overlooked, meaningfully shapes how PfAMA1 recognizes PfRON2.
- The perspective calls for future anti-malarial drug design to incorporate D2 loop dynamics alongside the trough itself, rather than treating the binding site as static.
If I'd been designing against the trough alone, I'd have built a static pharmacophore off one co-crystal pose and wondered why my analogs kept losing potency in ways the model couldn't explain — that's the D2 loop talking. A cryptic, conformation-dependent element next to your primary pocket means the 'druggable groove' you're staring at in PyMOL isn't the whole binding event; you need ensemble docking or short MD runs to even see the states worth targeting, not another round of rigid-receptor SBDD. This is the same lesson from Bcl-2/Mcl-1 and MDM2-p53 campaigns — flexible loops or helices near a defined hot spot often carry the selectivity, not the anchor pocket. No new chemical matter here, but it's a real prompt to revisit our PfAMA1 series with loop-aware ensembles before writing off SAR gaps as noise.