Today, only two boron delivery agents are approved for clinical use, the amino acid analog boronophenylalanine, known as BPA, and sodium borocaptate, known as BSH. Both have enabled meaningful advances, particularly in head and neck cancers and melanoma, but both carry well-recognized weaknesses. Tumor uptake can be heterogeneous, boron retention inside cells is often brief, and both agents depend on biological transport mechanisms that vary widely between patients and tumor types. A research team spanning institutions in Argentina and Uruguay has now reported a candidate designed to attack these limitations from a different angle — a single molecule that not only ferries boron into tumor cells but also attacks the cancer through an entirely separate pharmacological mechanism.

The compound, referred to in the study as Cmpd. 1, is a hybrid molecule built on the quinazoline scaffold of erlotinib, a widely used inhibitor of the epidermal growth factor receptor, or EGFR, a signaling protein that drives proliferation and survival in many lung cancers and, to a more variable degree, in melanoma. Fused to this kinase-inhibitor core is a carborane, a bulky, three-dimensional cluster rich in boron atoms. Earlier work by the same groups had shown that the compound inhibits wild-type EGFR and retains measurable activity against the T790M resistance mutation, displays favorable drug-like properties, and showed no mutagenicity or relevant acute oral toxicity in preclinical testing. In glioma models, it promoted selective boron accumulation and improved survival in mice. The new study, published in Frontiers in Chemical Biology, extends the platform to two new tumor contexts: cutaneous melanoma and non-small cell lung cancer.

The team began by profiling the two tumor models at the molecular level. Using quantitative real-time PCR, they found that the human lung cancer cell line NCI-H125 expressed markedly higher levels of both EGFR and LAT1 — the amino acid transporter responsible for shuttling BPA into cells — than the melanoma line Mel J. This biological asymmetry set up a natural experiment: a tumor heavily dependent on EGFR signaling and LAT1-mediated transport versus one with more modest expression of both. When the researchers measured sensitivity to the compound, the lung cancer cells proved more vulnerable, with a 24-hour IC50 of 39.73 micromolar compared with 60.79 micromolar in melanoma, a pattern consistent with the compound’s EGFR-directed design.

The boron delivery results were striking. Cells were incubated with the compound at a total boron concentration of 2.7 parts per million, roughly ninefold lower than the 25 parts per million supplied with BPA. Yet after 24 hours, the compound produced greater intracellular boron accumulation in both cell lines than BPA did. When uptake was normalized to the amount of boron actually added to the culture medium — a measure of delivery efficiency rather than sheer dose — the compound outperformed BPA by a factor of 56.65 in melanoma cells and 24.06 in lung cancer cells. Neutron autoradiography, performed with UV-C sensitization on cells grown on Lexan polycarbonate, confirmed that detectable particle tracks were generated in cells treated with the compound even at just 0.5 parts per million of boron-10, one-twentieth of the concentration used for BPA, supporting efficient intracellular delivery.

To test whether this translated into therapeutic effect, the researchers irradiated treated cells with a thermal neutron beam at the RA-3 nuclear reactor facility at Argentina’s Centro Atómico Ezeiza, calibrated to deliver a total physical dose of 2 gray. In vitro BNCT significantly reduced cell viability in both tumor models seven days after irradiation. In melanoma cells, BPA-mediated and compound-mediated BNCT produced comparable reductions. In lung cancer cells, however, the response was more pronounced, particularly with the new compound, suggesting that the EGFR-targeted approach may offer an edge in EGFR-dependent tumors. Notably, the compound alone also modestly but significantly reduced lung cancer cell viability even without irradiation, underscoring its dual nature.

Cell death analysis 48 hours after irradiation revealed mechanistic differences between the two tumor types. Fluorescence microscopy using Hoechst 33258, fluorescein diacetate and propidium iodide showed that BNCT predominantly induced necrotic death in melanoma cells, with necrosis reaching roughly 50 percent — an expected outcome given the high-linear-energy-transfer nature of the alpha and lithium particles, which shred cellular structures beyond repair. The lung cancer cells, by contrast, displayed a mixed response: compound-mediated BNCT produced approximately 35 percent apoptosis alongside 35 percent necrosis, a larger apoptotic fraction than BPA-mediated BNCT induced. The researchers suggest this apoptotic component may reflect suppression of EGFR-driven survival signaling through the PI3K/AKT and RAS/RAF/MEK/ERK pathways, effectively a pharmacological assist to the physical radiation damage.

The in vivo experiments strengthened the case considerably. Athymic nude mice bearing either melanoma or lung cancer xenografts received the compound intraperitoneally at 1 milligram per kilogram three times per week over an 18-day period, without any neutron irradiation. In both models, treatment significantly delayed tumor growth relative to vehicle controls, demonstrating that the compound’s intrinsic antitumor activity survives in living animals. Body weight remained stable throughout the treatment period in both models, with no significant differences between treated and control animals, suggesting the regimen was well tolerated. Boron biodistribution was then assessed at the end of the treatment schedule, one hour after a final administration. In the lung cancer model, co-administration of the compound with BPA yielded a tumor boron concentration of approximately 23 micrograms per gram of tissue — a tumor-to-blood ratio of 6.3, a tumor-to-surrounding-skin ratio of about 2.2 and a tumor-to-lung ratio of roughly 3.7, the last metric included as a disease-relevant parameter since normal lung would be a critical tissue in any future lung-directed application. In the melanoma model, the combination achieved about 16 micrograms per gram with a tumor-to-blood ratio near 4.7.

The authors are careful to note the boundaries of what these experiments show. Because biodistribution was measured at the end of a repeated-dose protocol, residual compound from prior injections may have contributed to the measured boron concentrations, and the design does not establish the compound’s independent biodistribution profile or allow a direct head-to-head comparison of tumor selectivity with BPA. The choice to evaluate the compound alongside BPA was informed by earlier experience with a structurally related boron-containing lapatinib derivative, which alone produced low tumor boron levels at a comparable intraperitoneal dose. Future work, the team writes, should optimize the administration route — potentially intravenous or intratumoral — before attempting an independent biodistribution assessment. Even so, the study establishes that an EGFR-targeted carborane-quinazoline can be incorporated into a BPA-based regimen without compromising preferential tumor boron accumulation, while simultaneously contributing antitumor activity of its own. As the search for next-generation boron carriers intensifies, molecules that fuse targeted kinase pharmacology with dense boron payloads offer a compelling blueprint: a therapy that softens up the tumor chemically before the neutrons finish the job.

Subject of Research: Development of an EGFR-targeted carborane-quinazoline compound that combines intrinsic antitumor activity with boron delivery for boron neutron capture therapy in melanoma and non-small cell lung cancer models.

Article Title: A bifunctional carborane-quinazoline combines tumor growth inhibition and boron delivery for boron neutron capture therapy in melanoma and non-small cell lung cancer models

Article References: Dagrosa, M. A., Carpano, M., Pastini, A., Pavlik, E., Bechis, A., Olivera, M. S., Vallecorsa, P., Dávila, B., Parodi, L., Salem, E. Y., Espain, M. S., Portu, A. M., Todaro, L., Urtreger, A., Menendez, P., Cerecetto, H., & Couto, M. (2026). A bifunctional carborane-quinazoline combines tumor growth inhibition and boron delivery for boron neutron capture therapy in melanoma and non-small cell lung cancer models. Frontiers in Chemical Biology, 5, Article 1945455. https://doi.org/10.3389/fchbi.2026.1945455

Image Credits: AI Generated

DOI: 10.3389/fchbi.2026.1945455

Keywords: boron neutron capture therapy, BNCT, carborane, quinazoline, EGFR, erlotinib, melanoma, non-small cell lung cancer, BPA, LAT1, boron delivery agents, targeted cancer therapy

The scientific foundation of this approach is the cholinergic hypothesis, one of the oldest and most extensively studied theories in Alzheimer’s research. It holds that the cognitive decline characteristic of the disease stems largely from the degeneration of cholinergic neurons, particularly in the nucleus basalis of Meynert, a deep brain region critical for attention and learning. When these neurons die, levels of acetylcholine plummet, and the enzyme acetylcholinesterase rapidly degrades what little remains in the synaptic cleft, splitting it into acetate and choline. Existing drugs such as donepezil, rivastigmine, and galantamine work by blocking this enzyme, temporarily boosting acetylcholine signalling. But they offer only symptomatic relief, and their effectiveness fades as cholinergic neurons continue to die.

What makes the new review compelling is its argument that acetylcholinesterase is far more than a passive cleanup enzyme. The authors assemble evidence that the enzyme actively worsens multiple Alzheimer’s pathologies. Through its peripheral anionic site, acetylcholinesterase binds amyloid-beta and accelerates its aggregation into toxic fibrils, forming complexes that are more damaging than amyloid alone. The enzyme is also linked to tau pathology, activating glycogen synthase kinase-3, which drives the hyperphosphorylation of tau protein that disrupts neuronal structure. Oxidative stress increases acetylcholinesterase expression, creating a vicious cycle in which cholinergic decline and cellular damage reinforce each other. Even genetic risk is entangled: the APOE4 allele interacts with butyrylcholinesterase to form complexes that are exceptionally efficient at degrading acetylcholine.

This multifunctional role of the enzyme has inspired a design philosophy known as multitarget-directed ligands. Rather than simply blocking the catalytic active site at the bottom of the enzyme’s deep gorge, modern candidates are engineered to also engage the peripheral anionic site, simultaneously boosting cholinergic signalling and interfering with amyloid aggregation. The review highlights how researchers have achieved this by taking scaffolds borrowed from nature, such as coumarin, xanthone, chalcone, quinoline, and quinazoline, and systematically modifying them through established organic reactions including Williamson ether synthesis, Claisen-Schmidt condensation, and microwave-assisted cyclisation.

The potency figures reported across these studies are striking. A hydrazinyl coumarin derivative synthesized via Hantzsch thiazoline condensation achieved an inhibitory concentration of 0.451 micromolar, outperforming donepezil itself, and significantly improved memory in scopolamine-treated mice. A coumarin-pyridinium bromide salt reached an extraordinary 2 nanomolar potency against acetylcholinesterase while protecting neuronal cells from oxidative damage. Among xanthones, a bis-alkyloxy derivative hit 0.328 micromolar, comparable to the withdrawn drug tacrine, while a xanthone-alkylbenzylamine hybrid reversed memory deficits in an amnesia mouse model at a predicted safe dose of 2500 milligrams per kilogram in rats.

Chalcone derivatives, built from two aromatic rings joined by an alpha-beta unsaturated carbonyl, delivered some of the most impressive numbers in the review. An oxindole-fused chalcone inhibited acetylcholinesterase at 0.10 micromolar and butyrylcholinesterase at 0.30 micromolar, with favourable blood-brain barrier permeability and low predicted toxicity. A pyridine-based chalcone not only inhibited the enzyme at 0.1 micromolar but also blocked 83.58 percent of amyloid-beta aggregation after 48 hours. In the quinazoline family, a mercapto-quinazoline candidate achieved 9.26 nanomolar inhibition, beating donepezil’s 16.43 nanomolar benchmark, and showed significant efficacy in a streptozotocin-induced mouse model of the disease.

Structure-activity relationship analysis reveals the chemical logic underlying these successes. For coumarins, substitution at the seventh position and a short alkyl linker are critical, with longer chains failing to deliver. In xanthones, pyrrolidine and phenyl substitutions enhance activity, and the terminal alkyne linker strengthens binding. Bromine-substituted chalcones bearing pyridine and benzylpiperazine rings show marked potency gains, as do trifluoromethyl and hydroxyl groups on the phenyl ring. For quinazolines, a fluorine atom at the third position of the phenyl ring significantly boosts inhibition, while electron-withdrawing groups and benzylpiperazine moieties improve both enzyme binding and brain penetration.

To place these candidates on a common footing, the authors performed their own molecular docking analysis against two well-characterized acetylcholinesterase crystal structures, PDB entries 1EVE and 4PQE. Using PyRx for scoring and Discovery Studio for visualization, they found that a phenyl-quinoline compound and a quinoline-thiosemicarbazone hybrid achieved the strongest binding energies, at minus 12.6 and minus 12.4 kilocalories per mole respectively. Other leads, including a coumarinyloxy acetohydroxamic derivative and a chromeno xanthone, formed favourable hydrogen bonds and pi-pi stacking interactions with key residues such as TYR337, TYR124, TRP286, and TYR341, suggesting genuine stabilization within the enzyme’s binding pocket rather than mere computational artefact.

The review is candid about the limitations. Most preclinical evidence comes from scopolamine and aluminium chloride-induced animal models, which capture cholinergic dysfunction but not the full complexity of human Alzheimer’s disease. Several candidates have failed clinically due to poor bioavailability, hepatotoxicity, and gastrointestinal side effects, and the historical withdrawal of tacrine for liver toxicity remains a cautionary tale. Clinical trials of cholinergic agents, catalogued from ClinicalTrials.gov, consistently show symptomatic improvement rather than disease modification. The authors argue that future work must move to transgenic models, refine pharmacokinetic profiles, and explore nanocarrier delivery systems such as liposomes and polymeric nanoparticles to improve drug stability and controlled release.

Nevertheless, the convergence of phytochemical inspiration, rational synthetic design, and computational validation represents a genuine shift in how the field approaches acetylcholinesterase. By treating the enzyme as a hub connecting cholinergic failure, amyloid toxicity, tau pathology, oxidative stress, and neuroinflammation, these synthetic modulators aim to do what single-target drugs could not: address several facets of the disease at once. The road from nanomolar enzyme inhibition to a proven, well-tolerated therapy is long, but the review makes a persuasive case that the chemical toolkit for that journey is now richer than ever.

Subject of Research: Synthetic phytochemical-inspired acetylcholinesterase inhibitors as multitarget therapeutic candidates for Alzheimer's disease

Article Title: Synthetic modulators of acetylcholinesterase: mechanistic, SAR, and therapeutic perspectives in Alzheimer’s disease

Article References: Ghose, A., Paidesetty, S. K., Prusty, S. K., Panda, P. K., Pattanaik, S., Pakeeraiah, K., Sahoo, S. S., & Sahu, P. K. (2026). Synthetic modulators of acetylcholinesterase: mechanistic, SAR, and therapeutic perspectives in Alzheimer’s disease. Journal of Saudi Chemical Society, 30(2), Article 25. https://doi.org/10.1007/s44442-026-00073-x

Image Credits: AI Generated

DOI: 10.1007/s44442-026-00073-x

Keywords: Alzheimer's disease, acetylcholinesterase inhibitors, multitarget-directed ligands, coumarin, chalcone, xanthone, quinoline, quinazoline, structure-activity relationships, molecular docking, neuroinflammation, amyloid-beta