Oncology
96 articles
Silencing PARP1 at the Gene Level: A G-Quadruplex-Binding Small Molecule Sidesteps PARP Inhibitor Toxicity
- Rather than inhibiting or trapping the PARP1 enzyme like approved PARP inhibitors (PARPis), researchers targeted the PARP1 gene promoter itself to shut down PARP1 production at the transcriptional level, aiming to avoid the hematologic toxicity and resistance mechanisms associated with PARPi-mediated PARP1 trapping.
- The promoter region forms a non-canonical (3+1) hybrid G-quadruplex structure distinguished by an adenine bulge, a distinctive DNA fold not previously exploited as a drug target.
- Combining computational modeling with biophysical characterization, the team identified a small molecule that selectively engages this unusual G-quadruplex architecture.
- In multiple myeloma cells, the compound reduced PARP1 expression, disrupted downstream DNA repair signaling, and triggered DNA damage-associated apoptosis.
- Healthy blood cells were largely spared, pointing to a possible therapeutic window distinct from conventional PARP inhibitor toxicity profiles.
The part that gets me: attacking PARP1 at the promoter instead of the active site. Every PARPi on the market — olaparib, niraparib, talazoparib — works by trapping or inhibiting the protein; the hematologic toxicity and trapping-driven resistance are baked into that mechanism. Silencing transcription via a G-quadruplex sidesteps the whole liability profile, at least on paper. That said, G4-targeting ligands are a rough class to work in — selectivity across the thousands of quadruplex-forming sequences in the genome is the perennial failure mode, not potency. And this (3+1) hybrid fold with an adenine bulge is a genuinely novel pocket, which cuts both ways: interesting SAR territory, but no playbook to lean on. Still early — a validated hit in MM cells, not a lead, let alone a candidate. Worth watching, not betting on yet.
Direct-to-Biology Approach Delivers a Selective GRP78 Inhibitor Probe
- GRP78 (BiP/HSPA5) is a chaperone in the highly conserved HSP70 family, making isoform-selective inhibitors difficult to design.
- Using a Direct-to-Biology (D2B) strategy — synthesizing and screening compounds without intermediate purification — researchers identified compound 12 as a selective GRP78 inhibitor.
- Compound 12 binds the peptide-binding pocket in GRP78's substrate-binding domain and is selective for GRP78 over other tested HSP70 isoforms.
- It potently and selectively kills A549 lung cancer cells while showing minimal activity in other tested lung cancer cell lines.
- Cellular thermal shift assay (CETSA) confirmed cellular target engagement, and compound 12 modulates GRP78-linked unfolded protein response (UPR) stress signaling.
- The authors present compound 12 as a chemical probe for studying GRP78 biology and a starting point for GRP78-targeted therapeutics.
Substrate-binding domain, not the ATPase pocket — that's the harder but more selective play, since most HSP70-family programs chase the nucleotide site and inherit its cross-reactivity problem. Getting selectivity for GRP78 over other HSP70 isoforms out of a peptide-binding groove is a real medicinal chemistry win; those pockets are shallow and promiscuous by design. What I'd want to see next: the SAR trail from D2B — crude-plate hits jumping straight to CETSA-confirmed engagement is fast, but I'd want a clean resynthesis and dose-response before trusting potency off unpurified reactions. Still, as a probe-grade starting point with A549-selective killing, compound 12 is a legitimate template for follow-on optimization, not another ATPase-site me-too.
Development of Isoform-Selective GRP78 Inhibitors from a Direct-to-Biology Strategy ↗
Covalent Small Molecule RVJB59 Stabilizes Two Cancer-Driving p53 Mutants
- p53 is the tumor suppressor most frequently inactivated in cancer, and hotspot mutations such as R280K and R273H destabilize the folded DNA-binding domain, making mutant p53 reactivation a long-standing 'undruggable' target class.
- The study describes RVJB59, a small molecule from a tryptophanol-derived oxazoloisoindolinone series, designed to covalently engage mutant p53 protein rather than bind it only reversibly.
- Biophysical thermal-stability assays reported for this compound series show increased melting stability of mutant p53 DNA-binding domains, consistent with partial restoration of a more folded, wild-type-like conformation.
- Combining covalent engagement with thermostabilization supports a mutant-reactivation strategy aimed at restoring p53 tumor-suppressor function in cancers driven by the R280K and R273H mutations.
Mutant p53 reactivation is the target class every oncology med chemist wants a win on — most p53 lesions are destabilizing loss-of-function, not a clean druggable pocket, so 'fix the fold' beats 'block the site.' RVJB59's angle — covalent engagement plus measurable thermal stabilization of R280K and R273H DBDs — is mechanistically the right read: lock a reactive residue, nudge the folding equilibrium back toward a wild-type-like conformation. My first questions are the covalent-chemist ones: which residue, what warhead, how clean is selectivity across the proteome — thermal-shift data alone won't settle that. Worth benchmarking against PC14586/rezatapopt's reversible pocket-binding approach for R175H; different mutant, different chemotype, same underlying bet. Reads as solid hit-to-lead chemical biology, not anything near clinic-ready.
TScan Guts 75% of Staff, Shelves Blood Cancer and Autoimmune Programs to Chase Solid Tumors
- TScan Therapeutics is pausing enrollment in its Phase 3 ALLOHA-2 trial of TSC-101, an allogeneic TCR-T therapy for blood cancers, citing insufficient funding to finish the study.
- The seven patients already dosed will keep being monitored; the company is now shopping the heme program to potential partners.
- TScan is also pausing its autoimmunity work, including its HLA-B*27 program in ankylosing spondylitis, while seeking outside partners for it as well.
- The company is cutting roughly 75% of its workforce and shutting down internal manufacturing to redirect resources toward its preclinical in vivo TCR-T platform for solid tumors.
- Management expects about $55 million in savings, pushing its cash runway out into Q4 2027.
Shelving a Phase 3 asset with seven patients already dosed — not a preclinical program — tells you where the real cash crunch sits. This isn't routine reprioritization; it's a company admitting it can't fund its most advanced bet to the finish line, however the release frames it. The pivot to in vivo TCR-T for solid tumors is bet-the-company: trading a derisked clinical program for an earlier-stage platform nobody has yet proven works in vivo. High conviction, but also a tacit admission the allogeneic heme franchise found no partner willing to bankroll it. Allogeneic TCR-T for blood cancers has gotten capital-intensive with thin differentiation between competitors — expect more heme/autoimmune cell-therapy assets to hit the partnering block as smaller players run short of runway before readouts. Reaching only Q4 2027 after cutting 75% of headcount suggests the burn problem was structural, not confined to the heme program.
TScan axes 75% of workforce to make room for solid tumor programs ↗
Roche's China Buying Spree Continues With $1.53B Simcere Antibody Deal
- Roche will pay Simcere Zaiming $75M upfront for exclusive global rights to SIM0660, with up to $1.53B in total milestones plus tiered double-digit royalties.
- SIM0660 is a preclinical trispecific antibody combining a CD3 T-cell-engaging arm with two B-cell-targeting arms against CD79a and CD19.
- Dual B-cell antigen targeting is designed to broaden coverage across malignant and autoimmune B-cell populations, including patients who progressed on CD20- or CD19-directed therapies.
- A cytokine-limiting design aims to address the tolerability issues that have dogged earlier T-cell engagers.
- The deal is Roche's third Chinese in-licensing agreement in just over a week, extending a multi-year pattern of sourcing early-stage oncology and immunology assets from Chinese biotechs.
Dual-antigen targeting (CD79a + CD19) is the differentiator — most B-cell engagers still chase one antigen, so this asset is explicitly built for patients who've already progressed on CD19- or CD20-directed therapy, a relapse population CAR-T and existing bispecifics can't fully cover. $75M upfront against $1.53B in milestones is textbook preclinical pricing: Roche caps its downside, Simcere Zaiming carries the early clinical risk, and most of the payout hinges on the cytokine-limiting design actually solving the tolerability problem that's dogged prior T-cell engagers. Three China deals in barely a week isn't bargain-hunting — it's a systematic pipeline-refill strategy, treating Chinese biotech as a faster, cheaper source of differentiated immuno-oncology chemistry than internal discovery. As more Western majors chase this playbook, though, China-originated multispecifics could get crowded and bid up before any clear pivotal data emerges.
Roche inks $1.53B deal for Simcere's B-cell-targeting antibody ↗
Genentech Licenses DualityBio's Next-Gen ADC Payload Platform to Counter TOPO1 Resistance
- Genentech has licensed DualityBio's DUPAC antibody-drug-conjugate payload platform: $45M upfront, over $1B in milestones, plus tiered royalties.
- Shanghai-based DualityBio handles target-specific ADC discovery through Phase 1a on Genentech-chosen oncology targets; Genentech then owns exclusive rights through late-stage development and commercialization.
- The rationale is payload resistance — topoisomerase-1 (TOP1) inhibitor payloads underpin most current ADCs, including DualityBio's own BioNTech-partnered HER2 asset, and resistance is rising as these drugs reach earlier treatment lines.
- DUPAC is pitched as a next-gen payload that stays active in TOP1-resistant tumors.
- This follows DualityBio's 2023 BioNTech deal (>$1.5B) and extends MNC pharma's pattern of sourcing ADC payload innovation from China.
The economics: $45M upfront against $1B+ in milestones is a cheap call option for Genentech — DualityBio absorbs discovery and Phase 1a risk, and Genentech only pays once DUPAC clears its resistance hurdle. That's a smaller headline number than DualityBio's 2023 BioNTech deal, hinting at either narrower scope or softer terms on partner #2. Strategically, this is Roche/Genentech hedging against a class-wide ceiling: TOP1 payloads underpin nearly the entire current ADC generation, including Enhertu and DualityBio's own BioNTech HER2 asset, so resistance will bite everyone eventually. It also confirms Genentech won't build payload discovery in-house, joining Pfizer/Seagen and AbbVie/ImmunoGen in sourcing ADC innovation from China. For DualityBio, a second nine-figure MNC partner in three years validates the platform model — though whether DUPAC actually beats resistant tumors is still unproven.
Roche bets $1B+ on DualityBio's ADC tech to tackle TOPO1 resistance ↗