Cationic Lipid Nanoparticles Emerge as Versatile Delivery Platforms for Cancer Therapy

Cancer treatment has long been constrained by a fundamental delivery problem: many of the most promising therapeutic molecules simply cannot reach tumor cells intact. A newly published review in Applied Microscopy by Chun-Sik Bae and Taeho Ahn synthesizes decades of research on cationic lipid-based nanoparticles, a family of positively charged carriers that has become one of the most extensively investigated platforms for ferrying fragile biological drugs—RNAs, proteins, and peptides—into malignant cells. The review, published on 2 April 2026, traces the field’s evolution from first-generation permanently charged lipids to next-generation ionizable architectures, and assesses how far these systems remain from routine clinical use in oncology.

The motivation behind this delivery technology lies in the shortcomings of conventional chemotherapy. Small-molecule anti-cancer drugs typically lack specificity and frequently cause severe systemic toxicity, while the emergence of multidrug resistance in cancer cells often forces premature discontinuation of treatment. In response, researchers have turned to highly potent macromolecular drugs, such as small interfering RNA for gene silencing and pro-apoptotic proteins and peptides. These so-called bio-drugs face their own critical barriers: inherent instability inside the body, the need for precise delivery to target sites, poor cellular uptake, and clearance by the immune system. Selective delivery systems have therefore become an indispensable strategy for realizing their therapeutic potential.

RNA interference sits at the heart of the review’s analysis. This conserved biological process silences gene expression by promoting the degradation of messenger RNA, using double-stranded non-coding RNA molecules such as siRNA, microRNAs, and short hairpin RNAs that act in a sequence-specific manner. The pathway begins when double-stranded RNA is cleaved into siRNA duplexes by the enzyme Dicer; these are then incorporated into the RNA-induced silencing complex, where the endonuclease Argonaute 2 unwinds the duplex and uses the guide strand to direct cleavage of the complementary target mRNA. Because siRNA binds only to mRNA with perfect complementarity, it typically induces highly specific gene silencing, and unlike gene therapies that integrate into the genome, it avoids risks of mutation and teratogenicity. RNAi therapies can target oncogenes driving uncontrolled cell division, silence multidrug resistance genes such as MDR1, inhibit anti-apoptotic factors to resensitize tumors to standard treatment, or block vascular endothelial growth factor to suppress tumor angiogenesis.

Getting siRNA into the cytosol, however, is far from straightforward. The anionic nature and high molecular mass of siRNA present significant barriers to crossing negatively charged cell membranes, and once inside, carrier vesicles are shuttled from early endosomes to late endosomes and eventually to lysosomes, where nucleases degrade the cargo. Endosomal escape—the release of siRNA into the cytosol at an early stage—is the rate-limiting step for efficient delivery, and it is estimated that less than 2% of delivered nucleic acid successfully escapes the endosomal compartment. Cationic lipid nanoparticles address this by exploiting electrostatic attraction: the cationic moiety interacts with anionic proteoglycans on the cell surface to trigger internalization, predominantly via clathrin-mediated endocytosis. Strategies to enhance endosomal escape include fusogenic lipids such as DOPE and pH-sensitive fusogenic peptides, which destabilize endosomal membranes in low-pH environments to release cargo into the cytoplasm.

The review organizes cationic lipid platforms into four major classes. Cationic liposomes, formed by complexation with nucleic acids to create lipoplexes of roughly 50 to 200 nanometers, are considered among the most attractive nanocarriers for siRNA delivery, offering ease of preparation, protection from degradation, and high transfection efficiency. Cationic solid lipid nanoparticles feature a rigid solid lipid core—composed of triglycerides, fatty acids, or waxes—with cationic lipids such as DOTAP integrated into the matrix, yielding zeta potentials typically between +25 and +44 millivolts; their stable framework enables sustained release and protects payloads from degradation. Stable nucleic acid lipid particles, or SNALPs, represent the gold standard for systemic siRNA delivery, combining ionizable cationic lipids that remain neutral at physiological pH with PEGylated stealth lipids, neutral helper lipids, and cholesterol. Finally, second-generation cationic nanostructured lipid carriers mix solid and liquid lipids to create a disordered internal structure that maximizes loading capacity and overcomes the drug-expulsion problems of crystalline solid lipid nanoparticles.

The SNALP platform achieved the field’s most significant clinical milestone with the 2018 FDA approval of Onpattro (patisiran), the first-ever RNAi therapeutic. While initially developed for liver-based genetic diseases, SNALP applications in oncology have expanded: they are now used to deliver siRNA against cancer-driving genes such as PLK1 and KRAS, and recent studies suggest they can simultaneously deliver siRNA for immune checkpoint knockdown, for example PD-L1, and mRNA for immune-stimulatory expression such as OX40L within the tumor microenvironment. The same architecture underpins mRNA vaccines, including those for COVID-19. Nevertheless, as of early 2026, while several RNAi therapies are FDA-approved for rare genetic and metabolic diseases, most cancer-specific RNAi therapies remain in clinical trial phases.

Beyond nucleic acids, the review surveys an expanding repertoire of cargos. Cytokines such as interleukins, interferons, and tumor necrosis factors can kill tumor cells directly or by regulating immune responses, but systemic use at high doses is severely restricted by dose-limiting toxicities that can lead to multi-organ failure, driving a shift toward targeted delivery and nanoparticle encapsulation. Pro-apoptotic proteins such as cytochrome c, whose mitochondrial release triggers the intrinsic apoptosis pathway, can be delivered directly into tumor cells to bypass internal survival signals, and TRAIL-mimetic peptides are being explored for their cell-death-inducing properties. Anti-cancer peptides, typically 5 to 50 amino acids long, exploit the negative surface charge and high membrane fluidity of cancer cells by forming membrane pores, targeting mitochondria, or inhibiting tumor blood vessel growth. Notably, lipoplex-based protein delivery is being repurposed from gene therapy: cationic lipids form complexes with anionic proteins, extending circulation half-life and preventing premature denaturation.

Perhaps the most provocative concept covered is the cargo-free, or self-therapeutic, nanoparticle. These systems exploit their inherent physicochemical attributes—chiefly the electrostatic attraction between positive surface charge and the negatively charged cancer cell membrane—to combat tumors without any traditional drug payload. Cationic guanidium-functionalized poly(l-lysine) self-assembles into particles that induce apoptosis in cancer cells, with recent research demonstrating efficacy comparable to drug-loaded versions in breast cancer models. Other cargo-free particles reprogram innate immune cell phenotypes to alter the tumor microenvironment, deliver tumor-associated antigens to dendritic cells, or act as intrinsic adjuvants whose positive charge serves as a danger signal promoting T-cell infiltration into immunologically cold tumors. Yet significant hurdles remain: non-biodegradable silica particles can accumulate in the liver and spleen, protein corona formation in the bloodstream can trigger immune clearance, and these particles struggle to penetrate dense tumor tissue because they lack a loaded drug to diffuse independently. Most such systems remain in preclinical stages.

The challenges confronting clinical translation are formidable and shared across platforms. High positive charges can damage cell membranes and induce hemolysis; upon intravenous injection, nanoparticles form protein coronas with serum proteins, leading to potential capillary blockade, thrombotic events, or rapid clearance by the mononuclear phagocyte system. Cationic liposomes are highly toxic to immune cells and may induce lung inflammation by stimulating reactive oxygen species production. Nanoparticles tend to bind the first cells they encounter at the tumor periphery, limiting deep penetration, while the enhanced permeability and retention effect that enables passive tumor accumulation is often absent at metastatic sites. Scaling up synthesis of complex, multifunctional carriers while maintaining consistent batch-to-batch properties remains a significant hurdle for regulatory approval.

The field’s response, the review argues, is a decisive shift toward smarter, charge-masked architectures. PEGylation creates a hydration layer that shields positive charge and extends circulation half-life, though repeated administration can induce anti-PEG antibodies and accelerated blood clearance. Ionizable lipids—neutral in the bloodstream but positively charged in acidic endosomes or the tumor microenvironment—are being applied across nearly all platforms to reduce toxicity. Biomimetic coatings derived from erythrocytes, platelets, or cancer cells allow particles to bypass immune surveillance, while active targeting ligands such as antibodies, aptamers, and folic acid direct binding to receptors overexpressed on malignant cells. Stimuli-responsive designs release cargo only in response to pH changes, tumor enzymes, redox potential, or external triggers like light and ultrasound. Looking ahead, the authors envision cationic lipid platforms evolving into theranostic systems integrating therapy with multimodal imaging, with artificial intelligence helping predict in vivo behavior from physicochemical characteristics—a convergence the review positions as defining the next generation of personalized precision oncology.

Subject of Research: Cationic lipid-based nanoparticles for therapeutic delivery in cancer treatment

Article Title: Cationic lipid-based nanoparticles for therapeutic delivery in cancer treatment: physicochemical characteristics, therapeutic cargos, and clinical potential

Article References: Bae, C.-S., & Ahn, T. (2026). Cationic lipid-based nanoparticles for therapeutic delivery in cancer treatment: physicochemical characteristics, therapeutic cargos, and clinical potential. Applied Microscopy, 56(1), Article 9. https://doi.org/10.1186/s42649-026-00130-0

Image Credits: AI Generated

DOI: 10.1186/s42649-026-00130-0

Keywords: cationic lipids, lipid nanoparticles, siRNA delivery, cancer therapy, drug delivery, lipoplexes, SNALP, solid lipid nanoparticles, nanostructured lipid carriers, tumor microenvironment, RNA interference, nanomedicine