Inhalable nanoparticle-based drug delivery system for non-small cell lung cancer therapy: promises and challenges.

Introduction
Lung cancer is currently the second most frequently diagnosed cancer and remains the leading cause of cancer-related deaths worldwide. According to the most recent global statistics from the International Agency for Research on Cancer (IARC, 2024), nearly 2.5 million individuals were diagnosed with lung cancer in 2022, and over 1.8 million died from the disease, underscoring its major public health burden. Lung cancer accounts for more than twice the number of deaths compared to colorectal cancer, the second leading cause (Organization n.d.).
Lung cancer is mainly categorized into two types: Non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). NSCLC, which accounts for about 85% of all lung cancer cases, progresses more slowly compared to SCLC. It includes subtypes such as adenocarcinoma, squamous cell carcinoma, and large cell carcinoma (Sharma et al. 2023). On the other hand, SCLC, which accounts for about 15% of cases, is known for its rapid progression and early metastasis. The focus of the review is on NSCLC, which comprises the highest percentage. While both subtypes differ in biology and systemic treatment strategies, the potential for inhaled nanoparticle-based therapies is more relevant to NSCLC, where localized pulmonary delivery can target primary or metastatic lesions in the lung. This review focuses on NSCLC (Xie et al. 2024).
For NSCLC, treatment includes surgery for early stages, and systemic chemotherapy, targeted therapy, or immunotherapy for advanced/unresectable cases, each treatment with unique mechanisms of action and applicability depending on the stage and subtype of cancer (Jong et al. 2023). Surgical resection is often considered the gold standard for localized NSCLC, particularly in the early stages where the tumor is confined and has not metastasized. In advanced lung cancer, however, the applicability of surgery is considerably limited. Around 55% of patients have stage IV or metastatic disease. At this stage, the tumors have spread beyond the primary site, making surgical intervention less feasible and often ineffective (Lackey small (a) Donington 2013).
Chemotherapy, a mainstay in the treatment of lung cancer, is generally more suitable for advanced stages of the disease. It is usually administered intravenously. This method was chosen to bypass first-pass metabolism and prevent degradation of the drug, ensuring maximum therapeutic efficacy. Despite its widespread use, chemotherapy is associated with a number of side effects, including nausea, hair loss, and fatigue, due to its non-specific effects and its impact on healthy tissue (Lee 2019).
In recent years, there has been a significant shift towards precision medicine (in) the treatment of lung cancer, with an increasing focus on targeted therapies and immunotherapy. These approaches aim to exploit specific molecular characteristics of cancer cells or harness the body's own immune response against the cancer. Such treatments have shown promise in improving outcomes and reducing side effects compared to conventional chemotherapy, particularly in patients with certain genetic mutations or biomarkers (Lee 2019; Pirker 2020).
The use of pulmonary drug delivery systems (PDDSs) in the treatment of NSCLC represents a significant advance in oncological therapy. These systems exploit the large surface area of the lung and its rich vascularization, which not only facilitates rapid drug absorption but also enhances nanoparticle penetration and potential retention in peritumoral regions. This physiological feature supports achieving higher drug concentrations at the tumor site while minimizing systemic exposure (Wang et al. 2022; Vagena et al. 2025). This method improves therapeutic efficacy, enables more targeted treatment of the primary tumor, and reduces the likelihood of unwanted side effects that often occur with conventional systemic chemotherapy (Gupta et al. 2022; Mangal et al. 2017).
Recent advancements in nanotechnology have further augmented the potential of drug delivery in the lungs. The integration of nanoparticles into inhalable chemotherapy formulations has proven to be a promising approach. These nanoparticles offer several advantages, as shown in Fig. 1: they provide enhanced drug protection (Andrade et al. 2013), improve pharmacokinetics, enable DNA/RNA encapsulation, and prolong circulation time (Zacaron et al. 2023). In addition, they facilitate targeted delivery and offer potential applications in imaging and diagnosis (Sharma et al. 2023).
Significant progress has been made in the development of inhalable nanocarriers for the localized treatment of NSCLC, aiming to enhance therapeutic precision while minimizing systemic toxicity. For example, Fu et al. developed a biomimetic liposomal system co-delivering osimertinib and a plasmid encoding IGF2BP3 siRNA, which mimicked lung surfactants to improve pulmonary deposition and triggered in vivo exosome production for targeting brain metastases, achieving notable tumor regression and immune activation (Fu et al. 2025). Similarly, Zhao et al. reported siKRAS@GCLPP nanoparticles for aerosolized delivery of siRNA against mutant KRAS, demonstrating efficient lung targeting, potent gene silencing, and superior safety over systemic administration in an orthotopic NSCLC model (Zhao et al. 2023). The aim of this review is to provide a comprehensive overview of the devices used in PDDSs for NSCLC, including recommendations for device selection. It also briefly outlines the key physicochemical characteristics of nanoparticles used in the delivery of chemotherapy. The review covers passive and active targeting strategies in nanoparticle drug delivery, as well as challenges in nanoparticle-mediated inhalation drug delivery for treating NSCLC. A major focus will be on the latest advancements in inhalable nanomaterials for the treatment of NSCLC. This review provides a current perspective on inhalable nanoparticle-based therapies for NSCLC. It covers studies published between 2013 and 2024, with an emphasis on research from the past 5–7 years to reflect the most recent advancements in the field.

Pulmonary delivery devices for nanotherapies in NSCLC
As part of recent advancements in the treatment of NSCLC, a variety of inhalation methods for the delivery of nanoparticle systems have been developed. These innovative methods aim to increase the effectiveness of drug delivery directly into the lungs, thereby improving treatment efficacy and minimizing systemic side effects. The main inhalable delivery devices are nebulizers, pressurized metered dose inhalers (pMDIs), and dry powder inhalers (DPIs). Each of these devices offers unique benefits and challenges and is shaping the landscape of pulmonary drug delivery in the treatment of NSCLC (Gupta et al. 2022; Al Khatib et al. 2023).

Nebulizers
Nebulizers are an important method of delivering high doses of anticancer drugs to the lungs. By converting liquid medication into a fine mist, they allow deep penetration into the lung. This approach is particularly compatible with simple formulations such as suspensions or solutions. An important advantage of nebulizers is their efficacy in evenly distributing nanomedicines, ensuring that the nanoparticles are evenly distributed over the lung surface. There are different types of nebulizers, such as ultrasonic nebulizers, vibrating mesh nebulizers (VMN) and jet (pneumatic) nebulizers, all of which are widely used for delivery to the lungs (Garrastazu Pereira et al. 2016). They are valued for their ability to deliver medication without the patient having to actively inhale and for their ability to deliver high doses. However, nebulizers are associated with some challenges. The nebulization process is time consuming and can lead to significant wastage of medication. However, according to Galindo-Filho et al. (2019), vibrating mesh nebulizers achieved an inhaled dose of 22.8% and lung deposition of 12.1%, compared with 12.5% and 3.1% for conventional jet nebulizers, respectively, while also leaving only 3% residual drug versus 46% in jet devices (Galindo-Filho et al. 2019). Furthermore, nebulization is mainly suitable for water-soluble drugs, so many lipid-based formulations are excluded. In addition, the liquid form of chemotherapeutic agents used in nebulizers often has poorer long-term stability than their dry counterparts (Cipolla et al. 2013).
Several studies have demonstrated the effectiveness of using a nebulizer for lung delivery in targeting cancer cells. Inhalable nanostructured lipid carriers encapsulating celecoxib (CXB-NLCs) have been developed for the treatment of lung cancer using compritol and miglyol as the lipid matrix and sodium taurocholate as the surfactant. These CXB-NLCs showed controlled release of CXB over 72 h and exhibited both time- and dose-dependent cytotoxic effects on A549 cells. In BALB/c mice, nebulized CXB-NLCs using PARI LC Star jet nebulizer achieved a lung area under the curve (AUC₀–t) approximately four times higher than that of a CXB solution (Patlolla et al. 2010). In another study, nebulized paclitaxel-loaded solid lipid nanoparticles (SLN-PTX) achieved significantly greater suppression of lung metastases compared to intravenously administered Taxol. While the IV group received 2.4 mg/kg of PTX per dose, the inhalation group was treated with 1.0 mg/kg per dose of SLN-PTX, demonstrating superior therapeutic efficacy at a lower dose and with no observed systemic toxicity (Videira et al. 2012).
Building on these preclinical findings, a Phase II clinical trial by Zarogoulidis et al. evaluated inhaled carboplatin in 60 stage IV NSCLC patients. Patients were randomized to receive carboplatin i.v., hybrid i.v. + inhaled, or inhaled-only, all with i.v. docetaxel. The hybrid regimen significantly improved survival (275 vs. 211 days with i.v. alone), while inhaled-only reduced neutropenia but showed no survival advantage and a modest decline in FEV₁. Treatment was generally well tolerated, with only transient cough and fever reported, supporting the feasibility of nebulized chemotherapy as a potential adjunct in NSCLC (Zarogoulidis et al. 2012).
In parallel, preclinical studies using a jet nebulizer to deliver inhaled submicron paclitaxel (PTX) (NanoPac; MMAD ≈ 2 µm) in an orthotopic NSCLC nude-rat model showed markedly higher tumor regression(≈55–65% vs 10% with i.v. nab-paclitaxel), occasional complete responses, and pronounced immune-cell infiltration. All animals tolerated the treatment without added toxicity, underscoring the potential of nebulized taxanes to achieve strong local tumor control while also engaging antitumor immunity (Verco et al. 2019).

Pressurized metered dose inhalers (pMDIs)
pMDIs are popular because of their portability and ease of use. The pMDI device consists of a canister containing the drug under high pressure in a plastic tube and a mouthpiece. When activated, it delivers a precise and consistent dose of the drug in the form of an aerosol (Zhou et al. 2014). However, pMDIs only deliver small doses (in the order of micrograms), which may not be sufficient for effective chemotherapeutics. The required coordination between actuation and inhalation poses a challenge for some users, especially the elderly. Together with the limited dosing capacity, this limits their suitability for NSCLC therapy (Muralidharan et al. 2015).
Zhong et al. developed PEGylated poly(amidoamine)-dendrimer-based doxorubicin (DOX) nanocarriers for the treatment of lung cancer using pMDIs. The aim was to achieve controlled DOX release and effective cellular targeting against human alveolar carcinoma cells (A549) without any clinical experiments. These nanocarriers, formulated in pMDIs with a minimal cosolvent, showed promising results in terms of controlled release, cell penetration, and deep deposition in the lung, emphasizing their potential as an efficient lung cancer therapy (Zhong And Rocha 2016).
In another in vitro study by Heyder et al., degradable polyester-based dendrimer nanocarriers were investigated using a model of the pulmonary epithelium (Calu-3 cell monolayers). This lab-based research did not involve animal or clinical studies. The work focused on hydroxyl-terminated G3 and G4 dendrimers, which showed a favorable compatibility and toxicity profile. The results demonstrated that transport efficiency depended on dendrimer generation and PEGylation. PEGylation also affected degradation and solvation, ultimately improving aerosol quality for deep lung deposition. These in vitro results indicate the potential of these dendrimers for lung targeting and systemic delivery via the pulmonary route (Heyder et al. 2017).

Dry powder inhalers (DPIs)
Inhalable nanoparticle-based dry powders were first introduced by Tsapis et al. using hollow porous carriers (Tsapis et al. 2002) and was further advanced by Sham et al. through spray-dried formulations containing nanoparticles for pulmonary administration (Sham et al. 2004).
When administering drugs in the lungs, DPIs have proven to be a remarkable method of administering drugs in the form of dry powder. The special feature of DPIs is their breath-activated mechanism, which eliminates the need for propellant gas and simplifies the inhalation process. This feature increases patient comfort in particular, as the application needs to be coordinated less precisely (Wauthoz et al. 2021). In addition, DPIs are designed for ease of use and self-administration. These aspects make DPIs a practical and efficient tool in respiratory medicine. In addition, DPIs have a longer shelf life compared to liquid medications. Furthermore, their efficacy is not affected by the solubility of the drug as the formulation is in the form of dry powder. Therefore, they are suitable for lipid-based anticancer drugs (Levet et al. 2016).
When considering the limitations of DPIs, it was noted that their efficacy may be compromised in high-humidity environments and that they require adequate patient airflow, which is challenging for people with severe respiratory disease. In addition, the efficacy of DPIs can be compromised by strong adhesive and cohesive interactions among powder particles or with the device surfaces, which hinder deagglomeration and aerosolization, thereby reducing the amount of drug reaching the lungs. These factors are critical in evaluating the suitability of DPIs for individual patient use, especially where environmental conditions and patient breathing capabilities vary (Peng et al. 2016; Deb et al. 2018). Moreover, the typical dose deposition per inhalation is limited to approximately 10 mg, which may restrict their use for formulations requiring higher payloads (Brunaugh And Smyth 2018).
To improve pulmonary deposition efficiency, spray freeze-dried powders have been developed, demonstrating deposition rates of up to 90% in the deep lung regions. Using this technique, Finlay, Roa, and Löbenberg formulated nanoparticle-based dry powders for aerosol delivery to the lungs (Finlay et al. n.d.).
In a recent study, researchers developed a spray-dried dry powder formulation of the antimicrobial peptide Nisin ZP specifically for NSCLC therapy. In this formulation, Nisin ZP was combined with mannitol, L-leucine, and trehalose, resulting in an optimized powder suitable for inhalation. The study, which investigated different drug concentrations, demonstrated improved delivery and therapeutic potential in NSCLC. Stability testing conducted over three months at 4 °C and 25 °C showed high stability, maintaining over 90% activity. This was confirmed by differential scanning calorimetry and X-ray diffraction analysis, which indicated preservation of the semi-crystalline powder structure (Patil et al. 2023).

Selection criteria for pulmonary drug delivery devices
Inhalable nanoformulations including lipid-based, polymeric, dendrimer, and inorganic systems possess distinct physicochemical characteristics such as size, surface charge, and stability that directly influence device selection in NSCLC therapy. These features are briefly introduced here, while more detailed discussion of nanoparticle properties is provided in Sect. 3 of this review.
The choice of a pulmonary drug delivery device for NSCLC treatment is influenced by several factors: the dosage amount, with pMDIs typically used for small doses (a few micrograms), while nebulizers and DPIs are preferred for larger payloads required in lung cancer therapy. Another critical parameter is the Mass Median Aerodynamic Diameter (MMAD). MMAD is the particle diameter at which half of the aerosol mass is made up of larger particles and half of smaller ones. Generally, nanocarriers such as micelles, and SLNs, with sizes ranging from 5 to 1000 nm, are designed for nebulization, as nebulizers can generate aerosols with aerodynamic diameters suitable for reaching the lower airways (Chang And Chan 2022). Conversely, formulations with particle sizes typically exceeding 5 µm, including microparticles and nano-in-microparticle systems, are more suitable for delivery via DPIs, which favor deposition in the central and upper lung regions. Selecting the appropriate MMAD according to the formulation and delivery device is essential to maximize deposition efficiency and therapeutic effect in NSCLC patients (Pilcer And Amighi 2010; Pilcer et al. 2012).
The aerosolization behavior of nanoparticles is a key factor influencing lung deposition. Parameters such as agglomeration, dispersibility, and hygroscopicity affect how particles are carried in the inhaled air stream. Poor aerosolization may lead to upper airway deposition or exhalation. Importantly, the mass median aerodynamic diameter (MMAD) determines where particles deposit in the respiratory tract. For efficient deep lung deposition, particles with MMADs between 1–5 µm are preferred. Nanoparticles are often incorporated into microparticles to meet this aerodynamic size requirement, then disaggregate at the lung surface to release the active nanoparticles (Pilcer And Amighi 2010; Shetty et al. 2020; Cheng 2014).
In general, nebulized nanocarriers, including polymeric, lipid-containing, and inorganic nanoparticles, are particularly valuable in NSCLC therapy due to their ability to bypass mucociliary clearance and target lung cancer cells, although there are concerns about their premature exhalation (Patlolla et al. 2010). DPIs, on the other hand, are capable of depositing microparticles deep in the lung. However, DPIs face particular challenges, such as opsonization by alveolar macrophages and impaired aerosolization due to the cohesiveness of the particles (Goel et al. 2013). To address these issues, advanced inhalable, bioresponsive, large-pored, and camouflaged lipid microparticles have recently been developed to improve the efficacy of pulmonary drug delivery (Levet et al. 2016). Notably, one of the earliest innovations in this field was reported by Ely et al. in 2007, who developed the first effervescent dry powder system to enhance pulmonary drug delivery performance (Ely et al. 2007). Figure 2 shows the main nanoparticles used for NSCLC drug delivery and the preferred inhalable devices for delivery (Gupta et al. 2022; Pilcer And Amighi 2010; Pilcer et al. 2012; Gandhi And Roy 2023).

Physicochemical properties of nanoparticles for pulmonary delivery of anti-cancer drugs
In cancer therapy, nanoparticles offer unique advantages due to their physicochemical properties (Fig. 3). The size of nanoparticles is critical for NSCLC penetration and clearance evasion (Zhang et al. 2021). Surface charge influences their interaction with NSCLC and biodistribution. Lipophilicity affects their ability to cross biological membranes (Peetla et al. 2009). Surface modifications enhance targeting specificity toward NSCLC (Ramamoorthy et al. 2023). These properties collectively enhance the efficacy of nanoparticle-based NSCLC treatments. This section will elaborate further on each of these properties.

Size of nanoparticles
The size of nanoparticles has a significant impact on the efficiency and mechanisms of cellular absorption, with optimal uptake generally achieved for particles between 10 and 500 nm. Size, together with surface properties, determines penetration routes such as phagocytosis and pinocytosis, with larger particles often internalized through micropinocytosis (Shin et al. 2015; Behzadi et al. 2017). Beyond cellular uptake, size also influences systemic distribution and clearance: nanoparticles smaller than 10 nm are rapidly eliminated by renal filtration, while tumor vascular cut-off pore sizes (380–780 nm) constrain extravasation, making 10–100 nm a widely recognized optimal diameter in cancer nanomedicine (Venturoli And Rippe 2005; Lee et al. 2014).
In pulmonary delivery, the aerodynamic size of nanoparticles critically determines their deposition, retention, and therapeutic efficacy in the lungs. Particles larger than ~ 5 µm tend to deposit in the upper respiratory tract due to inertial impaction, limiting their delivery to deep lung regions. In contrast, aerodynamic diameters between 1–5 µm are optimal for efficient penetration into the lower airways and alveoli (Negi et al. 2023). Within the nanoparticle range, submicron particles (< 500 nm) exhibit favorable diffusion behavior, facilitating alveolar deposition through Brownian motion while particles < 200 nm are less likely to be cleared by alveolar macrophages (Deng et al. 2021). Specifically, human studies have shown that particles in the 50–100 nm range deposit effectively in peripheral airways, with deposition influenced by lung capacity and breathing dynamics.
Recently, the cytotoxicity of inhaled silver nanoparticles of different sizes was investigated by Braakhuis et al. in healthy, non–tumor-bearing Fischer rats. Animals were exposed to aerosols containing 18, 34, 60, or 160 nm silver nanoparticles for four consecutive days, and pulmonary responses were evaluated. The study showed that smaller nanoparticles (18 and 34 nm) induced a concentration-dependent increase in lactate dehydrogenase and total protein in bronchoalveolar lavage fluid, indicating greater cellular damage, while such effects were not observed with the larger nanoparticles (60 and 160 nm). Importantly, because the material composition was identical across groups (all silver), the increased toxicity was attributed to nanoparticle size, with surface area–driven effects and ion release explaining the heightened inflammatory response. Larger particles, although more prevalent in the lungs overall, showed less alveolar deposition and slower clearance, while smaller particles reached the alveoli in greater numbers and were associated with stronger neutrophilic inflammation. These findings support the concept that particle surface area in the alveoli is the most suitable dose metric to describe acute pulmonary toxicity of inhaled nanoparticles (Shin et al. 2015).

Surface charge of nanoparticles
Surface charge critically influences how particles interact with the lung microenvironment, shaping their uptake, distribution, and subsequent immune activation. Fromen et al. investigated how particle surface charge influences pulmonary immune responses, focusing on cationic versus anionic formulations. Using PRINT-engineered nanoparticles administered to mouse lungs, they found that while both types trafficked to draining lymph nodes, alveolar macrophages showed a preference for internalizing anionic particles, whereas dendritic cell subsets (CD11b and CD103) associated more strongly with cationic particles. Importantly, cationic formulations upregulated chemokines such as Ccl2 and Cxcl10, leading to increased dendritic cell recruitment and maturation, without causing overt inflammation or systemic toxicity. These effects translated into enhanced local antigen-specific immune responses, establishing cationic particles as superior carriers for pulmonary immunization, whereas anionic particles remained largely immunologically inert and may serve in tolerance-inducing approaches. Collectively, the findings highlight surface charge as a critical design parameter for pulmonary vaccines and potential immunotherapy strategies relevant to NSCLC (Fromen et al. 2016).
Another study by Mousseau and Berret examined the influence of surface charge on nanoparticle–surfactant interactions using in vitro surfactant substitutes, including Curosurf®. Aluminum oxide, silicon dioxide, and latex nanoparticles were tested, and results showed that electrostatic forces promoted spontaneous aggregation with surfactant vesicles, forming intermixed structures where particles acted as connectors between vesicles. Contrary to predictions, supported lipid bilayer formation did not occur. These findings suggest that inhaled nanoparticles can significantly alter the structural and interfacial properties of pulmonary surfactants, potentially impairing alveolar stability and lung physiology (Mousseau And Berret 2018).
Beyond surface charge, surface coatings also play a significant role in pulmonary safety. Notably, Al-Hallak et al. (2010) evaluated Tween 80 (Polysorbate 80)-coated inhalable nanoparticles and reported considerable pulmonary toxicity in both in vitro and in vivo settings. These findings highlight the importance of carefully selecting surfactants and stabilizers in the formulation of inhalable nanocarriers to minimize adverse biological responses(Al-Hallak et al. 2010).

Lipophilicity of nanoparticles
The residence time of a drug in the lungs is a critical determinant of therapeutic efficacy. Compounds with a log P (partition coefficient) greater than 0 are more lipophilic, enabling them to cross pulmonary lipid barriers rapidly and undergo faster absorption (Wang et al. 2020a). In contrast, drugs with lower lipophilicity (log P < 0) remain longer in the aqueous lining fluid, thereby maximizing local exposure to the tumor. This balance between absorption and retention can be optimized through salt formulations or by modifying drug composition (Gupta et al. 2022; Kumar et al. 2022).
Drug diffusion in the lungs is strongly influenced by the mucus barrier, which particularly impedes lipophilic compounds with poor aqueous solubility. Such drugs, and lipophilic nanoparticles, can interact with lipids and glycoproteins in mucus, leading to entrapment and reduced bioavailability over time. Upon deposition in the upper lung, particles immediately encounter this mucus lining, making surface lipophilicity a key determinant of their ability to reach deeper tissues (Sigurdsson et al. 2013). This relationship is especially relevant in lung adenocarcinomas, a subtype of NSCLC arising from mucus-producing epithelial cells, where excessive mucus secretion further limits delivery efficiency (Bhimji And Wallen 2023).

Nanoparticle surface modifications
The interaction between nanoparticles and cells can be significantly influenced by the presence of specific ligands on the surface of the nanoparticles. By adding different ligands and functional groups to nano-carriers, their properties can be altered to improve selective interaction with NSCLC, a concept further emphasized in the active targeting section of this review. This targeted approach not only improves the efficacy of the particles, but also enables the development of lower-dose formulations (Gupta et al. 2022; Kumar et al. 2022). In NSCLC, targeting specific receptors that are frequently overexpressed in these malignancies is a key strategy. Nanoparticles containing therapeutic agents can be modified with ligands that target these specific receptors, increasing the precision and efficacy of treatment(Sharma et al. 2023).
A very well-known type of nanoparticles with a modified surface is stealth nanoparticles. It represents a significant advancement in nanomedicine, particularly due to their surface modification with polyethylene glycol (PEG) or other hydrophilic polymers. These sterically stabilized nanoparticles are characterized by their slightly negative or positive surface charges, which typically result in minimal interactions with themselves and other entities (Behnam et al. 2018; Zahednezhad et al. 2021). PEGylation plays a critical role in reducing macrophage uptake, primarily by repelling opsonization and minimizing protein adsorption on their surfaces. This process is further detailed in subsequent studies. Additionally, PEGylation has been identified as a key factor in prolonging the half-life of nanoparticles, highlighting the importance of surface modifications in their design. (Behzadi et al. 2017).
Ray et al. developed inhalable poly(ethylene glycol)–poly(lactic-co-glycolic acid) (PEG–PLGA)-based nanoassemblies for the pulmonary delivery of TMTP1, a metastasis-specific tumor-homing peptide. The formulation showed efficient lung deposition and metabolic stability, along with enhanced reactive oxygen species generation, autophagic flux, and apoptotic cell death in A549 cells. In vivo studies in an NNK-induced lung cancer model revealed significant tumor regression with limited toxicity, supporting the potential of TMTP1-loaded inhalable nanoparticles for targeted NSCLC therapy (Ray et al. 2024a).
While surface modification of nanoparticles offers significant advantages for stability, targeting, and reduced toxicity, several challenges must be considered in the design of systems for pulmonary delivery. The orientation and density of surface ligands can alter particle size and uptake efficiency, while non-covalent coatings may lose stability under varying pH or ionic conditions in the lung. Certain modifications, such as cationic coatings, may increase cytotoxicity and hemocompatibility issues, whereas commonly used polymers like PEG can trigger anti-PEG immune responses, leading to faster clearance (Elmowafy et al. 2023).

Passive and active targeting strategies in nanoparticle drug delivery

Passive targeting
Passive targeting in the context of nanoparticle drug delivery refers to the process by which nanoparticles naturally accumulate in specific tissues or organs without the need for any specific targeting ligands or modifications. This phenomenon is primarily leveraged in the treatment of solid tumors through the enhanced permeability and retention (EPR) effect (Bazak et al. 2014).
The EPR effect is a characteristic of many solid tumors, where the blood vessels are leaky due to rapid and abnormal growth, allowing nanoparticles to pass through the gaps in the vessel walls and accumulate in the tumor tissue. Additionally, the lymphatic drainage in tumors is often impaired, leading to the retention of the nanoparticles within the tumor site (Subhan et al. 2021).
Passive targeting relies on the physicochemical properties of the nanoparticles, such as size, shape, and surface charge, to optimize their accumulation in the target tissue. While this approach is less specific than active targeting, it is simpler to implement and can still provide a degree of selective delivery to enhance the efficacy of cancer therapies with reduced systemic toxicity (Herdiana et al. 2021).

Active targeting
Active targeting represents a refinement over passive strategies, as it allows NPs not only to accumulate in the tumor interstitium but also to selectively interact with cancer cells. This approach involves decorating the NP surface with specific moieties such as antibodies, peptides, aptamers, carbohydrates, or small molecules, which are designed to bind to receptors or membrane proteins overexpressed on tumor cells (Fig. 4) (Bazak et al. 2015; Arafat et al. 2024). By exploiting receptor–ligand interactions, active targeting enhances cellular uptake through receptor-mediated endocytosis, thereby improving drug accumulation at the desired site, minimizing systemic exposure to cytotoxic drugs, and reducing off-target effects (Gupta et al. 2022; Kumar et al. 2022). Despite these advantages, the incorporation of targeting ligands may increase recognition by macrophages and accelerate clearance by the mononuclear phagocyte system, underscoring the need to balance targeting efficiency with immune evasion (Wu et al. 2022). In NSCLC, several receptors and tumor-associated markers have been investigated as potential targets.
Among them, the transferrin receptors (TfR1) are known to be overexpressed in cancer cells, which is particularly noticeable in NSCLC. TfR1 has been found to be significantly overexpressed in lung tumors, up to 32 times more frequently than in normal cells (Villalobos-Manzo et al. 2022). Building on this principle, Zhan et al. developed an innovative tumor-targeting peptide, XQ1, which was grafted onto camptothecin (CPT) nanocrystals using a polydopamine coating as a linker. This novel drug formulation was more potent than free CPT and showed better selectivity against tumor tissue, especially against the A549 cell line. Highlighting, the therapeutic advantage of TfR1-mediated targeting (Zhan et al. 2017).
Vascular endothelial growth factor (VEGF), a key regulator of angiogenesis, is also overexpressed in NSCLC (Dvorak 2002). Oral administration of bovine lactoferrin (BLF) has been shown to downregulate VEGF expression in NSCLC cells, suggesting its dual role as a therapeutic agent and a targeting moiety when incorporated into nanoparticle formulations (Sharma et al. 2023).
The luteinizing hormone-releasing hormone (LHRH) receptor, similarly overexpressed in NSCLC, has been exploited in nanostructured lipid carriers for inhalable paclitaxel delivery, achieving a 16-fold increase in apoptosis compared to free drug and highlighting the potential of receptor-mediated inhalation strategies (Taratula et al. 2013).
Additional tumor-associated markers, including carcinoembryonic antigen (CEA), cytokeratin-19 fragment, and squamous cell carcinoma antigen, as well as carbohydrate antigens such as CA125, CA15-3, CA19-9, and CA72-4, are frequently elevated in NSCLC and represent further opportunities for ligand development (Chen et al. 2018; Stieber et al. 1993; Kumari et al. 2023). Collectively, these findings demonstrate that receptor- and marker-specific surface modifications can substantially improve the selectivity and therapeutic efficacy of nanoparticle systems in NSCLC (Table 1).

Challenges in nanoparticle-mediated inhalation drug delivery for treating NSCLC
Nanoparticle-based PDDSs have emerged as a promising approach for targeting NSCLC, offering the potential for enhanced therapeutic efficacy, and reduced systemic side effects. Nevertheless, despite these advantages, their clinical implementation remains complex, as several critical barriers must be overcome before widespread adoption. One of the primary concerns is the risk of exposing the lungs to high concentrations of the drug, which could exacerbate the condition of patients, particularly those with compromised lung function (Lee et al. 2015).
A major set of barriers arises from the lung’s own defense and clearance mechanisms, which are highly efficient at eliminating foreign particles, including nanoparticles. This innate efficiency, while essential for respiratory health, poses significant obstacles for maintaining therapeutic levels of inhaled nanoparticles in NSCLC therapy (Mangal et al. 2017).
Mucociliary clearance is a defence mechanism that involves the coordinated movement of cilia, hair-like structures on the surface of respiratory epithelial cells, which propel a layer of mucus towards the throat. This mucus layer acts as a physical trap for inhaled particles, including nanoparticles, and its steady transport ensures rapid elimination from the respiratory tract. When considering pulmonary clearance, distinguishing between aerosol droplet size and nanoparticle size is critical: droplet size (aerodynamic diameter, MMAD) governs deposition in the respiratory tract (1–5 µm for alveoli, > 6 µm for upper airways), while nanoparticle size (< 200 nm) dictates how particles behave after deposition, including mucus diffusion, macrophage uptake, and tumor penetration (Shen And Minko 2020). Particles with aerodynamic diameters exceeding 6 µm are primarily deposited in the oropharyngeal region and are generally excluded from pulmonary delivery considerations. These particles are removed by being trapped in mucus and then expelled from the trachea through coughing or swallowing. However, smaller particles often bypass the mucociliary escalator and reach the alveolar region, where they can persist longer and potentially deposit near tumor sites (Gupta et al. 2022; Abdelaziz et al. 2018).
Another critical clearance pathway is phagocytosis by alveolar macrophages. These immune cells reside primarily in the alveolar region (the site of gas exchange), where they engulf and digest foreign particles. This mechanism efficiently clears particles in the size range of 1.5 to 3 µm (Mangal et al. 2017; Abdelaziz et al. 2018). While this process protects the lungs, it also shortens the residence time of therapeutic nanoparticles.
Another important factor involves barriers to drug absorption that persist even after clearance is bypassed. Nanoparticles reaching the alveolar region must still overcome obstacles such as the alveolar–capillary membrane, tight junctions, mucus viscosity, and tumor microenvironment, all of which can limit drug penetration into cancer cells (Labiris And Dolovich 2003).
In contrast, oral administration is challenged by entirely different barriers. Nanoparticles taken orally face enzymatic degradation in the gastrointestinal tract and first-pass metabolism in the liver, both of which greatly reduce systemic bioavailability. Although oral delivery is convenient for patients and avoids direct lung irritation, it is generally less effective for lung-targeted therapies than inhalation. This comparison highlights the need to understand clearance mechanisms across different routes when designing optimized nanoparticle systems (Date et al. 2016).
To overcome these barriers, nanoparticles must be engineered to persist long enough at the target site without compromising lung function. Current approaches include surface modification, precise size optimization, and the use of biodegradable materials, all aimed at improving delivery efficiency and safety in NSCLC therapy (Iyer et al. 2015).
Equally important is the interaction between nanoparticles and lung surfactant films. Prenner et al. investigated gelatin and PLGA nanoparticles using biomimetic surfactant models and demonstrated that nanoparticle size and surface properties strongly influence surfactant stability (Daear et al. 2022). Because the surfactant layer is essential for normal lung mechanics, its disruption could impair pulmonary function, especially in patients with pre-existing respiratory disease. These findings emphasize that nanoparticle–surfactant interactions must be carefully evaluated during formulation development to ensure safety and compatibility(Daear et al. 2022; Ku et al. 2008; Lai et al. 2010).
Beyond clearance and biocompatibility, tumor heterogeneity adds another layer of complexity. NSCLC varies in histology, genetic alterations, and microenvironmental features, all of which can affect drug distribution and therapeutic response (Oh et al. 2025). Anatomical factors, such as tumor location (central vs. peripheral airways), airway narrowing, or mucus buildup, also influence aerosol deposition (Darquenne et al. 2024). At the microscopic level, intratumoral variability in vascularity, cell density, and molecular target expression may lead to uneven drug uptake (Lavi et al. 2013). These challenges highlight the need for adaptable, patient-specific inhalation strategies.
Finally, regulatory requirements remain a major obstacle to clinical translation. Inhalable nanoparticle formulations must undergo comprehensive safety assessments, strict quality control, and detailed evaluations of aerosol performance and device compatibility. Yet, regulatory guidance specific to inhaled nanomedicines is still limited. Agencies such as the FDA and EMA require robust data on safety, efficacy, and manufacturing consistency (Cojocaru et al. 2024). Engaging with regulators early and adopting standardized protocols will be crucial for advancing inhaled nanoparticle therapies into clinical practice (Rodríguez-Gómez et al. 2025).
Beyond established barriers, emerging challenges in pulmonary nano-delivery include patient variability such as breathing patterns, airway changes and mucus hypersecretion, long-term safety concerns including chronic inflammation, immunogenicity and nanoparticle accumulation, and underexplored areas such as device–formulation compatibility, large-scale manufacturing and interactions with co-medications in NSCLC patients. Addressing these gaps will be critical for advancing inhaled nanomedicines toward successful clinical translation.

Macrophage polarization in cancer therapy: the role of nanoparticles
The tumor microenvironment is a complex milieu where various cell types interact dynamically, influencing NSCLC progression and treatment outcomes. Among these cells, tumor-associated macrophages (TAMs), which are macrophages that are specifically associated with tumors and influenced by the tumor microenvironment, play a pivotal role, exhibiting diverse phenotypes that either bolster or impede NSCLC progression (Basak et al. 2023). This interplay is governed by the polarization of macrophages into distinct phenotypes, primarily the M1 and M2 phenotypes, each characterized by unique functional properties and cytokine profiles. M1 macrophages, activated by factors like interferon-gamma (IFN-γ) and lipopolysaccharide (LPS), exert pro-inflammatory and tumoricidal effects, while M2 macrophages, induced by cytokines such as interleukin-4 (IL-4) and interleukin-10 (IL-10), promote an immunosuppressive environment conducive to tumor growth and metastasis (Atri et al. 2018; Strizova et al. 2023).
The delicate balance between M1 and M2 macrophages within the tumor microenvironment is a critical determinant of cancer progression and response to therapy. Strategies aimed at shifting this balance towards the pro-inflammatory M1 phenotype or inhibiting the immunosuppressive M2 phenotype hold great therapeutic potential. One such strategy involves the use of nanoparticles, which have emerged as versatile tools for precisely modulating macrophage polarization (Fig. 5) (Wang et al. 2021).
Nanoparticles offer several advantages for targeted macrophage modulation. By functionalizing their surfaces with ligands that bind to specific macrophage receptors, nanoparticles can selectively target and deliver therapeutic agents to either M1 or M2 macrophages (Medrano-Bosch et al. 2021). For instance, nanoparticles coated with antibodies against M2 macrophage markers can effectively reprogram these cells toward an anti-tumoral M1 phenotype. Moreover, nanoparticles can be loaded with immunomodulatory agents such as toll-like receptor agonists or small interfering RNAs, enabling precise control over macrophage polarization and enhancing their anti-tumor activities (Shi And Gu 2021).
Overall, the use of nanoparticles to modulate macrophage polarization represents a promising strategy for improving the efficacy of anticancer therapies. By targeting and reprogramming macrophages within the tumor microenvironment, nanoparticles have the potential to enhance the body's immune response against NSCLC and overcome resistance to conventional treatments. This review explores the current state of nanoparticle-mediated macrophage modulation and its implications for future NSCLC therapy strategies (Reichel et al. 2019).
A study conducted by Muhammad Sarfraz et al. investigated the impact of nanoparticle-treated macrophages on NSCLC cell viability, focusing on acute inflammation and cytokine release. The study aimed to elucidate the therapeutic potential of this inflammatory response. Using various drug-loaded nanoparticles, including gelatin and poly(isobutyl cyanoacrylate), the researchers observed a substantial decrease of 40–62% in A549 lung cancer cell viability post-treatment. These results underscored the crucial role of macrophages in nanoparticle-mediated cytotoxicity against NSCLC cells and highlighted the potential for leveraging their inflammatory response in NSCLC therapy (Sarfraz et al. 2016).
Furthermore, Multiple antibodies targeting IL-6 have shown clinical benefits in NSCLC patients, though their impact on TAM reprogramming remains unexplored. For example, ALD518, a humanized anti-IL-6 antibody, was evaluated in a randomized phase II clinical trial and was well tolerated, demonstrating improvements in anemia and cachexia, although effects on tumor reduction or survival were not established (Bayliss et al. 2011).

Nanoparticle used in the development of inhalable targeted NSCLC
Nanoparticles are emerging as a critical component in the development of targeted therapies for NSCLC. These includes a variety of nanoparticles (Fig. 6), such as lipid-based nanoparticles [SLNs, NLCs, and lipid–polymer hybrid nanoparticles (LPHNPs)], as well as polymeric nanoparticles, inorganic nanoparticles, and dendrimer-based nanoparticles. Taken together, these nanoparticles offer a wide range of possibilities for developing more effective and targeted treatments for NSCLC. Several studies have demonstrated the efficacy of using these delivery systems for inhaled delivery of anticancer drugs for NSCLC.

Lipid-based nanoparticle
Lipid-based nanoparticles have become increasingly important in the development of inhalable drugs for the treatment of NSCLC. The main developed are SLNs, NLCs and Lipid-polymer hybrid nanoparticle (LPHNCs). Their versatility enables efficient delivery of therapeutics directly into the lung, which is essential for the treatment of lung-specific diseases such as NSCLC. Lipid-based carriers offer several advantages over other types of carriers. They are biodegradable and non-toxic and allow for prolonged drug release. In addition, they can penetrate the phospholipid membrane barriers of NSCLC cells and are able to cross blood vessels (Viegas et al. 2023).

Solid lipid nanoparticle
SLNs have a solid lipid core enveloped by a surfactant layer, designed to enhance the DDS stability when exposed to aqueous environments. The lipid material composition employed in SLN formulations is notably varied, including a range of different elements (Pandey et al. 2021). Lipid materials in SLN formulations comprise triglycerides (such as tristearin), partial glycerides (for instance, glyceryl behenate), fatty acids (for example, decanoic acid), steroids including cholesterol, and various waxes (Santonocito et al. 2023; Bhagwat et al. 2020; Bayón-Cordero et al. 2019). This intricate arrangement allows SLNs to maintain their integrity and functionality in various biological settings. Common surfactants used in SLN include poloxamers, lecithins, sodium glycocholate, polysorbates, sorbitan esters, and their combinations (Akanda et al. 2023). However, SLNs encountered considerable obstacles due to their limited drug loading capacity and the possibility of drug expulsion during storage. Commonly, these nanoparticles are produced through methods like high-pressure homogenization or micro-emulsification (Jacob et al. 2020). Generally, SLNs are most suitable for lipophilic drugs, as they can be efficiently incorporated into the solid lipid matrix and achieve stable loading. Hydrophilic drugs are generally difficult to encapsulate, with only highly potent, low-dose hydrophilic agents being feasible unless modified through lipid–drug conjugates (Mukherjee et al. 2009).
Several studies have demonstrated the effectiveness of SLN in the treatment of NSCLC through inhalation (Haque et al. 2018). However, a study conducted by Haque et al. showed that SLNs tend to accumulate in the upper respiratory tract, particularly in the bronchial region, mainly due to aggregation and enhanced mucoadhesion that favor mucociliary clearance. In contrast, larger SLNs retained in the pulmonary area were associated with prolonged drug exposure and extended bioavailability (Haque et al. 2018).
Erlotinib (ETB) is a common second-line treatment for advanced NSCLC. Currently, ETB is administered orally, but delivering it directly to lung cancer cells could improve its effectiveness. A dry powder inhaler with ETB-SLN was formulated. The ETB-SLNs were prepared using the hot homogenization technique, combining compritol and poloxamer 407 in their formulation. Evaluation through MTT assay and DAPI staining showed enhanced cytotoxic effects of ETB-SLNs on human alveolar adenocarcinoma epithelial A549 cells, making them a relevant model for NSCLC (Bakhtiary et al. 2017).
Gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, has shown promise in NSCLC therapy, but its use is associated with some toxicities. Gefitinib-loaded glucosamine-targeted solid lipid nanoparticles (Gef-G-SLNs) were developed using an emulsion-solvent diffusion and evaporation method for localized delivery to lung tumors. The formulation was prepared as dry powder. In vitro testing demonstrated that Gef-G-SLNs exhibited enhanced effectiveness compared to the free form of the drug. Moreover, flow cytometry and fluorescence microscopy revealed a greater uptake of G-SLNs by A549 lung cancer cells compared to non-targeted SLNs (Satari et al. 2020).
Gemcitabine and oxaliplatin were co-loaded into oleic acid-based SLNs. The formulation was prepared using hot homogenization. The anti-tumor activities were assessed against A549 NSCLC. The formulation exhibited a remarkable reduction in tumor growth over 24 h. Additionally, a superior effect of the formulation on autophagy (326.38 ± 4.21 pg/ml) was observed compared to the control cells (206.2 ± 6.69 pg/ml) (Al-Mutairi et al. 2021).

Nanostructured lipid nanoparticle
The development of NLCs has overcome several limitations of conventional SLNs, such as low drug loading capacity and drug excretion after storage (Ghasemiyeh And Mohammadi-Samani 2018). Their unique structure consists of tiny liquid nano-compartments of oil within the SLN matrix. Consequently, NLCs differ from SLNs mainly by the inclusion of liquid lipid in the SLN matrix, resulting in an amorphous structure of the lipid core. This increases the solubility of the drug and the overall loading capacity but impairs the stability of the PDDSs. Moreover, an organic solvent is required to encapsulate the hydrophobic drug due to its low solubility in NLC (Viegas et al. 2023).
NLC was prepared using a modified melt-ultrasonic dispersion technique to deliver DOX, an anticancer drug, and short interfering RNA (siRNA) directly to the lung for targeted NSCLC treatment. This NLC system is intended for inhalation and facilitates direct administration into the lung (Taratula et al. 2013). Various studies have been conducted on human NSCLC and animal studies using a mouse lung cancer model. The results showed that the NLC efficiently transported its therapeutic agents directly to the lung cancer cells while sparing healthy lung tissue. Crucially, unlike intravenous injections, NLC significantly reduces the exposure of healthy organs to the therapeutic agents (Taratula et al. 2013).
The efficacy of aerosolized CXB-NLC in the treatment of NSCLC was investigated both as a single treatment and in combination with intravenously administered docetaxel (DTX). High-pressure homogenization was used to produce CXB-NLC nanoparticles with a mean particle size of 217 ± 20nm and an entrapment efficiency of over 90%. As monotherapies, CXB-NLC and DTX showed a reduction in tumor size of 25 ± 4% and 37 ± 5%, respectively, compared to the untreated control group. When administered concurrently, CXB-NLC and DTX synergistically produced a remarkable 67 ± 4% reduction in tumor size, highlighting the therapeutic potential of their combined use (Patel et al. 2013).
Despite the promising potential of NLCs as drug delivery carriers, there is a limited number of both preclinical and clinical studies. To advance their potential, it is crucial to broaden their application to include clinical trials conducted within appropriate ethical frameworks (Kim et al. 2023).

Lipid-polymer hybrid nanoparticle
The emergence of biodegradable lipids and polymers in the development of nanocarriers for the treatment of NSCLC has shown a certain superiority over other types of nanocarriers. The polymer component, which forms the core of the nanocarriers, increases their physical stability and structural integrity (Wei et al. 2020). The liposomal bilayer surrounding the polymer core increases the affinity to the cells and improves uptake into the cells. PEG is integrated into the outer layer of the cell to extend the duration of action by preventing rapid excretion. It also prevents aggregation of the nanocarrier (Abbasi et al. 2022).
In a remarkable advance in PDDSs, researchers have developed an inhalable dry powder that utilizes LPHNCs for the delivery of DTX. This formulation overcomes the low water solubility of DTX, which often necessitates the use of a nonionic surfactant and ethanol, leading to patient hypersensitivity. The team used two design methods, the Plackett–Burman design and the Box–Behnken design, to optimize the LPHNCs. Freeze-drying using a Virtis Advance lyophilizer and various cryoprotectants improved the retention of the drug. In addition, a special dry powder inhaler was developed to improve the aerodynamic properties of the powder. This led to an improved release of DTX from the LPHNCs, as evidenced by a fine particle fraction of 68.3 ± 2.5% and a retention rate of 98.3 ± 3.1%.
Another research by Wang et al. (2019) developed transferrin-modified, redox-sensitive lipid–polymer hybrid nanoparticles (Tf-SS-Afa-LPNs) for the delivery of afatinib in NSCLC. In vitro, these nanoparticles showed GSH-triggered drug release and enhanced cytotoxicity in NSCLC cell lines, while in vivo they achieved prolonged circulation, greater tumor accumulation, and significantly reduced tumor volume (919 mm3 to 212 mm3) in xenograft mice compared to free afatinib. These results emphasize the potential of LPHNCs as anticancer drug carriers for the treatment of NSCLC via pulmonary delivery, though further studies are needed to confirm their effectiveness(Bardoliwala et al. 2021).

Polymer nanoparticles
Polymers have been used extensively in the formulation of nanoparticles for the uptake of chemotherapeutic agents due to their diverse composition. These macromolecules are composed of smaller units, called monomers, which are linked together by covalent bonds to form a variety of structures (Begines et al. 2020). Polymeric colloidal particles can encapsulate drugs in their polymeric matrix or conjugate them to their surface (Sánchez et al. 2020; Mitchell et al. 2021).
In recent years, the use of inhalable polymeric nanoparticles has attracted increasing interest as a potential treatment strategy for NSCLC. Their attractiveness stems from important properties, including the ability to integrate specific targeting ligands on their surface, which significantly enhances their efficacy. This property increases their selectivity towards tumor cells and thus improves treatment outcomes. In addition, these nanoparticles facilitate the sustained release of drugs, prolonging their therapeutic effect and potentially addressing the problem of drug resistance (Madej et al. 2022; Zhang et al. 2023).
Resveratrol, a natural polyphenol, exhibits antitumor properties. However, its use in the treatment of NSCLC is limited due to its low water solubility, stability and bioavailability. Wang et al. addressed these issues by loading a resveratrol-sulfobutyl ether-β-cyclodextrin complex onto a PLGA copolymer. This modification increased the water solubility of resveratrol by 66-fold and improved the accumulation of nanoparticles in the lung. In addition, an increase in antitumor activity against NSCLC was demonstrated in a 3D spheroid study (Wang et al. 2020b).
The clinical application of afatinib is also limited due to its poor solubility. To address this, inhalable PLGA nanoparticles loaded with afatinib have been developed, showing promising physicochemical and inhalation properties, stability, and efficacy for NSCLC therapy. These nanoparticles have a particle size of 180.2 ± 15.6 nm, a zeta potential of −23.1 ± 0.2 mV, and an entrapment efficiency of 34.4 ± 2.3%. The negative zeta potential prevents particle aggregation and ensures stability for up to four weeks at different temperatures. Additionally, a sustained release was observed, with 56.8 ± 6.4% released after 48 h (Elbatanony et al. 2021).
Numerous studies have explored modifying nanoparticles with cationic polymers for NSCLC drug delivery (Garg 2022). Cationically modified nanoparticles show increased cellular uptake and tumor penetration due to the anionic nature of tumor cell surfaces (Chen et al. 2016). Sorafenib, a kinase inhibitor effective against various tumors, has limited use in NSCLC due to significant side effects and low bioavailability, requiring higher doses. To address this, sorafenib has been loaded into inhalable polymeric nanoparticles modified with poly-l-arginine (PLA). These nanoparticles have a cationic zeta potential of 16.2 ± 1.3 mV and effective aerodynamic properties, enhancing NSCLC cell uptake and significantly reducing cell survival (Shukla et al. 2020).
Chitosan, a polymer composed of N-acetyl-D-glucosamine and D-glucosamine units, is widely used to formulate polymeric nanocarriers due to its biodegradability, nontoxicity, ease of preparation, and stability (Labiris And Dolovich 2003). Almutairi et al. encapsulated raloxifene in nanoparticles of chitosan and hyaluronic acid to increase its bioavailability. These nanoparticles inhibited the viability of the lung cancer cell line A549 by increasing nitric oxide levels and inducing apoptosis. Chitosan can also be combined with other polymers like alginate, a biocompatible and biodegradable polymer. PEGylated chitosan-alginate nanoparticles, designed to bind DOX via an acid-labile amide bond, have a hydrodynamic diameter of 205.7 ± 15.0 nm and a negative zeta potential of −25.17 ± 2.67 mV. They release DOX in response to pH changes, making them suitable for lung delivery via inhalation therapy. Moreover, the study showed that DOX-PEG nanoparticles had clear anti-tumor efficacy in vitro against A549 NSCLC cells, producing dose- and time-dependent cytotoxicity. Although slightly less potent than free DOX (due to controlled release), the system offers the advantage of sustained, pH-triggered activity with reduced toxicity to healthy cells (Ak 2021). The 2’-O-methylRNA (OMR) antisense oligonucleotide is a potent human telomerase inhibitor but suffers from poor cellular uptake, reducing its intracellular availability (Juliano et al. 2014). Dong et al. improved this by using chitosan-coated PLGA nanoparticles loaded with OMR, significantly enhancing pulmonary distribution and cellular uptake. These nanoparticles, prepared via the emulsion diffusion evaporation method, were 160 nm (± 2 nm) in size and showed no negative effects on lung physiological parameters. Administered via an endotracheal aerosol using a microsprayer needle, these nanoparticles ensured effective delivery (Dong et al. 2012).
Similarly, Ray et al. formulated inhalable chitosan-coated poly(ε-caprolactone) nanoassemblies (CS-PCL-NAs) for the pulmonary delivery of niclosamide (NIC), a repurposed anthelmintic agent with demonstrated anticancer activity. The formulation exhibited favorable aerodynamic properties for inhalation, efficient lung deposition, and significant tumor retention in a murine model of NSCLC. In vitro, studies on A549 cells revealed dose-dependent inhibition of cell proliferation, alongside enhanced autophagy flux and apoptosis induction. In vivo, the nanoassemblies achieved substantial tumor regression with minimal systemic toxicity, supporting their potential as a localized, mechanism-driven nanotherapy for NSCLC (Ray et al. 2024b).
Another study used a pH-dependent technique by Guo et al. designed multi-functional chitosan–gold nanocluster nanoparticles functionalized with the AS1411 aptamer (targets nucleolin) to deliver methotrexate (MTX) for lung cancer (A549, NSCLC). The construct (MTX@AuNCs-CS-AS1411) averaged ~ 200 nm with ~ 13.8% MTX loading and showed pH-dependent release. In vitro, it was selectively internalized by A549 cells (time-dependent uptake), increased apoptosis, and produced stronger cytotoxicity than free MTX or non-targeted controls. In vivo (BALB/c nude mice with A549 xenografts), IV dosing led to tumor-selective accumulation by fluorescence imaging and significant tumor growth inhibition without overt toxicity. Overall, targeted, imaging-capable chitosan nanoparticles improved MTX delivery and antitumor efficacy while maintaining biocompatibility (Guo et al. 2018).
Polyethylenimine (PEI) is a cationic hydrophilic polymer with high transfection efficiency due to the proton sponge effect (PSE), which allows it to escape lysosomal entrapment and increases nanoparticle stability. Vaidya et al. studied quinacrine (QA), an antimalarial drug, for treating NSCLC. Initially, incorporating QA into PLGA polymers resulted in low entrapment efficiency. However, adding 2% PEI nearly doubled the entrapment efficiency from 26.3 ± 1.9% to 56.5 ± 1.8%. These PEI-PLGA nanoparticles showed enhanced antiproliferative activity against NSCLC cell lines (A549, H4006, and H157), with low IC50 values, inhibition of autophagy, and increased apoptosis (Vaidya et al. 2020).
Shan et al. recently developed silibinin-loaded poly caprolactone/pluronic F68 inhalable nanoparticles. Silibinin, a plant extract, has been shown to inhibit certain types of NSCLC. To improve the pharmacokinetics of silibinin, including its solubility and bioavailability, it was encapsulated in a polymeric nanoparticle of polycaprolactone and combined with pluronic F68. Pluronic F68 acts as a surfactant and improves the stability of the nanoparticles and the release properties of the drug. These inhaled polymeric nanoparticles had a targeted effect on lung tumors and led to a significant inhibition of tumor growth in lung tumor-induced rats after inhalation (Hou et al. 2018).
The use of polymer-based DDSs in NSCLC has gained increasing attention for overcoming the limitations of conventional chemotherapy, such as poor solubility and non-specific toxicity. For example, An et al. (2019) developed octreotide (OCT)-modified polymeric micelles co-loaded with curcumin and docetaxel using the amphiphilic polymer Soluplus to enhance drug solubility, tumor targeting, and anti-metastatic efficacy. The micelles, approximately 66 nm in size with high encapsulation efficiency (> 90%), exhibited superior in vitro cytotoxicity against A549 cells. They also showed enhanced cellular uptake via somatostatin receptor-mediated endocytosis and significantly inhibited vasculogenic mimicry (VM), cell migration, and adhesion. In terms of mechanism of action, the system downregulated metastasis-associated proteins HIF-1α and MMP-2. In vivo, the micelles showed increased tumor accumulation and the greatest reduction in tumor volume and weight among tested groups (An et al. 2019).
Similarly, Gong et al. (2020) explored the use of mPEG-b-PLA-Phe(Boc) micelles to improve docetaxel delivery in NSCLC. Their DTX-loaded micelles (DTX-PMs) showed high encapsulation efficiency (> 95%), excellent stability, and enhanced solubility. Compared to the commercial formulation Taxotere®, these micelles provided better tumor targeting, longer circulation time, and reduced off-target effects. Impressively, DTX-PMs achieved similar or even better antitumor efficacy at only half the drug dose, supporting their promise in reducing toxicity while maintaining therapeutic (Gong et al. 2020).
In another study conducted by Saadatzadeh et al. (2018), polymeric micelles were engineered for the pulmonary delivery of PTX in NSCLC therapy. Using a blend of D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS1K) and a novel TPGS5K analog, the researchers formulated mixed micelles with significantly reduced critical micelle concentrations and enhanced drug entrapment efficiency (up to 41%). These micelles were subsequently co-spray-dried with lactose to create inhalable dry powder particles suitable for deep lung deposition. The PTX-loaded micelles showed sustained drug release, superior cytotoxicity against A549 lung cancer cells, and favorable aerodynamic properties (MMAD ~ 3.8 μm, FPF ~ 60%). This study highlights the potential of TPGS-based polymeric micelles as a stable and effective platform for localized inhalation therapy in NSCLC (Rezazadeh et al. 2018).
Overall, these studies highlight the growing potential of polymeric micelles to enhance drug delivery and treatment outcomes in non-small cell lung cancer.

In-organic nanoparticles
Conventional organic-based nano-systems face limitations like restricted drug loading capacity and low thermal stability. However, new technologies offer more stable and efficient options. For instance, inorganic nanoparticles such as metal and metal oxide nanoparticles, along with MSN, have emerged (Porrang et al. 2022). Beyond chemical and thermal stability, an additional critical factor for pulmonary applications is the ability of nanoparticles to maintain their structural integrity and drug payload during nebulization, as the aerosolization process can induce aggregation or premature drug release. This section discusses recent studies using these inorganic nanoparticles for delivering chemotherapeutic drugs, with attention to challenges such as toxicity, solubility, selectivity, and stability under aerosolization conditions.
Magnetic nanoparticles (MNPs) have aroused great interest in nanotechnology due to their versatile application possibilities. These nanoparticles are mainly used in the administration of cancer therapeutics and in diagnostic imaging, especially as contrast agents in magnetic resonance imaging. In addition, MNPs have the unique ability to exhibit superparamagnetic behavior, in which magnetization occurs exclusively under an external magnetic field, facilitating the targeted release of drugs at specific sites. Common types of magnetic iron oxide nanoparticles include magnetite (Fe₃O₄) and maghemite (γ-Fe₂O₃) (Akhter et al. 2015).
Quercetin, a dietary flavonoid, is known for its anti-cancer properties, including inhibition of growth factors, suppression of cell proliferation and triggering of apoptosis (Lotfi et al. 2023). To take advantage of these effects, a magnetic nanocarrier was developed consisting of an Fe2O3 core coated with PLGA, specifically for the uptake of quercetin. The PLGA coating on the surface improves biocompatibility and prevents the aggregation of nanoparticles. This nanocarrier system has been shown to be particularly effective for nebulized delivery targeting lung cancer (Verma et al. 2013).
Magnetic hyperthermia, a non-invasive method of NSCLC treatment, uses superparamagnetic substances to generate heat under an external magnetic field to effectively destroy NSCLC (Sharma et al. 2023). This technique has proven to be a promising option for the treatment of various types of cancer, including breast cancer, cervical cancer, melanoma, and lung cancer. To enhance the effect of superparamagnetic agents on lung tumors, T. Sadhukha et al. developed inhalable superparamagnetic iron oxide (SPIO) nanoparticles. These nanoparticles target the EGFR, which is overexpressed in approximately 70% of patients with NSCLC. Inhaled delivery of these EGFR-targeted SPIO nanoparticles results in improved intra-tumoral distribution and significant inhibition of tumor growth when magnetic hyperthermia is applied (Sadhukha et al. 2013).
MSNs serve as another type of inorganic nanoscale drug carriers. Their large surface area and pore volume enable high loading efficiency of therapeutic agents. The experiments of Taratula et al. highlighted the efficacy of an inhaled MSN-based DDSs in the delivery of anticancer drugs (DOX and cisplatin) and siRNA target MRP1 or BCL2 mRNA, thus contributing to the control of drug resistance. To target NSCLC, a tumor-targeting component, LHRH peptide, was also conjugated to the MSNs. This conjugation ensures that the nanoparticles only target NSCLC, which generally overexpress LHRH receptors. The inhalation method led to a significant accumulation of MSNs in the lungs of mice, while preventing uptake into other organs, resulting in increased cytotoxic activity (Taratula et al. 2011). The surfaces of MSNs can be modified with receptor-specific proteins for targeted drug delivery. Additionally, they can be coated with nanoparticles or polymers to improve the controlled release of drugs and enhance stability. This modification can potentially decrease the possible side effects and toxicity associated with inorganic nanoparticles (Vivero-Escoto et al. 2010).

Dendrimers
Dendrimers, known as "unimolecular micelles", due to their apolar core and polar shell structure, were first called dendrimers in the early 1980s. Their name is derived from the Greek word "dendra"," which means "tree" (Bonacucina et al. 2009). The unique "reactive end groups" of dendrimers enable regulated branching (topology), controlled molecular weight assembly (monodispersity) and versatility in the design and modification of end groups (Tomalia et al. 1985). The release of drugs from micelles or dendrimers involves the diffusion of drugs and the degradation of the micelle or dendrimer structure. Factors that influence the rate of drug release include the rate of drug diffusion within the delivery system, the drug partition coefficient, the stability of the dendrimers and the rate of polymer degradation (Bonacucina et al. 2009).
Drugs can be bound to dendrimer surfaces by covalent or electrostatic interactions, which increases the bioavailability and solubility of drugs, facilitates controlled release and enables targeted delivery (Bai And Ahsan 2009). Safety and loading capacity are critical when considering a polymer for use as a drug carrier. Although low generation dendrimers (generation 4 or below) have favorable biological properties, such as minimal toxicity and reduced immunogenicity in vivo, their small internal cavities and limited reaction surfaces limit the number of guest molecules they can encapsulate compared to higher generation dendrimers (Roberts et al. 1996).
The administration of DOX-conjugated dendrimers via the pulmonary route has demonstrated positive outcomes. This efficacy prompted a comparative study with intratracheal D-DOX and intravenous DOX to explore the enhanced chemotherapeutic effect. Plasma pharmacokinetic data show that the dendrimer releases DOX in the lung in a continuous and controlled manner. This sustained release maintains low drug concentrations that effectively inhibit tumor growth while minimizing potential lung damage. In addition, intratracheal administration moves the dendrimer from the airways of the lung into the expanding peri-tumoral regions. Consequently, this method results in lung tumors containing DOX in a concentration that is 100 times higher than when the drug is administered intravenously in the form of a solution (Kaminskas et al. 2014).
In a study exploring new therapeutic strategies for NSCLC, MicroRNA-34a (MiR-34a) a potent tumor suppressor was successfully encapsulated in dendrimers bound to S6 aptamers, resulting in targeted gene delivery nanoparticles (PAM-Ap/pMiR-34a NPs). These nanoparticles exhibited a size of 100–200 nm and a zeta potential of about 30 mV, which was optimized with a specific N/P ratio. Conjugation with the aptamer significantly improved cellular uptake and gene transfection efficiency in NSCLC cell cultures. PAM-Ap/pMiR-34a NPs were shown to effectively regulate target genes such as p53 and BCL-2 in vitro. Moreover, in contrast to non-targeted nanoparticles, these targeted nanoparticles inhibited proliferation, migration and invasion of NSCLC and promoted apoptosis. This method represents an innovative approach for the experimental treatment of NSCLC (Wang et al. 2015).
The use of dendrimers as PDDSs for chemotherapeutic agents has been limited by factors such as toxicity and low loading efficacy. However, various studies have proposed new techniques to address these limitations (Nguyen et al. 2015; Madaan et al. 2014). For example, Nguyen et al. employed sonication to prepare a nanocomplex comprising equated cisplatin and carboxylated PAMAM dendrimer G3.5, with the goal of evaluating its loading capacity and platinum release behavior using analytical techniques including fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, nuclear magnetic resonance spectroscopy, ICP-AES, and transmission electron microscopy. Their results showed that the loading of cisplatin reached 25.20 and 27.83 wt/wt% under stirring and sonication conditions, respectively, marking a notable improvement in loading efficiency compared to the conventional cisplatin method. Moreover, in vitro studies demonstrated that this drug-nanocarrier complex could mitigate the cytotoxicity of cisplatin while preserving its sufficient antiproliferative activity against the lung cancer cell line NCI-H460, with an IC50 value of 0.985 ± 0.01 μM (Nguyen et al. 2015).
Table 2 summarizes all the studies discussed in the previous section regarding the use of inhalable nanoparticles for delivering anticancer drugs in NSCLC.

Although a considerable number of preclinical studies have investigated the efficacy of inhalable nanoparticle-based DDSs for NSCLC, only a few have progressed to clinical evaluation. For example, a Phase I trial assessed aerosolized Sustained Release Lipid Inhalation Targeting (SLIT) Cisplatin in 17 patients with advanced NSCLC (Wittgen et al., 2007). The liposomal formulation was administered via nebulization in escalating doses up to 60 mg/m2. Notably, no dose-limiting toxicities were observed, and systemic toxicities commonly associated with intravenous cisplatin, such as nephrotoxicity and myelosuppression, were absent. Instead, most adverse events were localized to the respiratory tract, including dyspnea, hoarseness, and cough, and were generally reversible. Pulmonary function tests showed mild, transient reductions in FEV₁ and DLCO, further supporting the tolerability of the inhaled formulation. In line with the targeted delivery strategy, pharmacokinetic analysis revealed minimal systemic absorption. While no objective tumor responses were reported, stable disease was achieved in 12 patients (Wittgen et al. 2007). This trial highlights the feasibility and tolerability of inhaled nanoparticle-based chemotherapy and underscores the need for further clinical studies to explore its therapeutic potential.

Conclusion
In summary, conventional NSCLC therapies are often limited by systemic toxicity and low efficacy in advanced disease stages. These limitations highlight the urgent need for innovative treatment approaches. Inhaled therapy, especially when combined with nanocarrier-based systems, presents a promising alternative. It enables localized drug delivery, improves pharmacokinetics, reduces systemic side effects, and enhances patient compliance.
Nanocarriers offer several advantages. These include high drug loading capacity, biocompatibility, and surface modifiability for targeted and controlled drug release. However, the choice of a suitable pulmonary delivery device remains crucial to ensure optimal therapeutic benefit. Nebulizers are generally preferred for nano-sized formulations (typically in the 5 to 1000 nm range), whereas dry powder inhalers (DPIs) are more suitable for larger, micron-sized particles or nanoparticle aggregates. However, DPIs face limitations such as low drug payload capacity, macrophage-mediated clearance, and poor aerosolization efficiency, particularly with larger or aggregated particles.
Despite these advancements, several challenges remain. The lungs have efficient clearance mechanisms, such as mucociliary transport and phagocytosis by alveolar macrophages. These mechanisms can hinder nanoparticle deposition and retention. DDSs are further complicated in patients with impaired lung function, and high local drug concentrations may increase the risk of toxicity.
Future research should aim to overcome these limitations. Strategies may include designing stealth nanoparticles that evade immune recognition and optimizing particle size and surface chemistry to enhance lung penetration and retention. Developing stimuli-responsive or smart-release systems could enable drug release in response to specific tumor microenvironment cues. Moreover, incorporating imaging or diagnostic agents into inhalable nanocarriers may help monitor drug distribution and therapeutic outcomes in real time.
Addressing these barriers is essential to advance inhaled nanoparticle therapies from preclinical success to clinical application. Continued collaboration across materials science, aerosol engineering, pharmacology, and oncology will be key to unlocking the full potential of inhaled nanomedicine for the treatment of NSCLC.