Nonsmall-cell lung cancer treatment: current status of drug repurposing and nanoparticle-based drug delivery systems

Drug repurposing is the strategy of drug utilization for a treatment option other than the intended indications. This strategy has witnessed increased adoption over the past decades, especially within cancer nanomedicine. Cancer nanomedicine has been facilitated through nanoparticle-based (NP-based) delivery systems which can combat nonsmall-cell lung cancer (NSCLC) via recent advances in nanotechnology and apply its benefits to existing drugs. The repurposing of drugs, coupled with NP-based drug delivery systems, presents a promising avenue for achieving effective therapeutic solutions with accelerated outcomes. This review aims to present an overview of NSCLC treatments, with a specific focus on drug repurposing. It seeks to elucidate the latest advances in clinical studies and the utilization of NP-based drug delivery systems tailored for NSCLC treatment. First, the molecular mechanisms of Food and Drug Administration (FDA)-approved drugs for NSCLC, including ROS1 tyrosine kinase inhibitors (TKI) like repotrectinib, approved in November 2023, are detailed. Further, in vitro studies employing a combination strategy of drug repurposing and NP-based drug delivery systems as a treatment approach against NSCLC are listed. It includes the latest study on nanoparticle-based drug delivery systems loaded with repurposed drugs.

Treatment options for NSCLC are surgery, radiation, chemotherapy, targeted treatments, and immunotherapy alone or in combination (Thai et al., 2021).These options are evolving thanks to advancements in screening technologies, a deeper understanding of disease mechanisms, and ongoing investigations into the effectiveness of existing therapies.Examples include immune checkpoint inhibitor therapy for advanced NSCLC patients, lobectomy for earlystage NSCLC patients, and postoperative radiotherapy for unresectable stage III NSCLC patients (Mouritzen et al., 2021;Thai et al., 2021).Understanding disease mechanisms has facilitated the design of target-specific drugs with the use of nanotechnological systems (Fan et al., 2023a).Recent advances in NP-based drug delivery systems leverage targeted drug delivery to overcome obstacles like systemic distribution and drug side effects (Dang and Guan, 2020;Fan et al., 2023a).
This review provides an overview of repurposed NSCLC drugs, along with currently used NSCLC drugs, and NPbased drug delivery systems tailored for NSCLC (Figure 1).
TKIs are main molecules of targeted therapy against pathways related to the regulation of cell growth in NSCLC via binding of receptor tyrosine kinase.Among 19 receptor kinase families identified in the human genome (Robinson et al., 2000), ALK, EGFR, MET, and RET tyrosine kinases have become targets for the treatment of NSCLC (Broekman et al., 2011).This is due to the presence of oncogenic driver mutations for NSCLC occurring on ALK, EGFR, ROS1, V-raf murine sarcoma viral oncogene homolog B (BRAF), (MET, NTRK, RET, KRAS, Human epidermal growth factor 2 (HER2) and NRG1 (Chevallier et al., 2021).ALK-TKIs were discovered through the molecular characterization of NSCLC, specifically with the identification of the EML4-ALK fusion gene (Soda et al., 2007).Crizotinib was the first ALK-TKI approved by the FDA in 2011, leading to a shift in first-line therapy option was changed from pemetrexedplus-platinum to crizotinib for the ALK-positive NSCLC (Malik et al., 2014;Solomon et al., 2014).The drug targets ALK, ROS-1, and c-MET but causes resistance in long-term administration by bypassing the blood-brain barrier leading to poor brain penetration (Costa et al., 2011;Casaluce et al., 2016).Following the discovery of crizotinib, other ALK-TKIs have been developed, including ceritinib, alectinib, brigatinib (AP26113), and lorlatinib (Testa et al., 2023).While these ALK-TKIs overcome the brain penetration problem, ALK-TKI resistance mechanisms remain a challenge (Testa et al., 2023) even for the third-generation ALK-TKI lorlatinib which acts as an ATP-competitive small molecule inhibitor (Syed, 2019).Repotrectinib, the most recently approved TKI, received approval in November 2023.It specifically targets ROS1-positive NSCLC patients (FDA, 2023) 2 .It is a TRIDENT-1 trial (NCT03093116) drug and showed an overall response rate of 14.8 (7.6-NE) months and a progression-free survival of 9.0 (6.8-19.7)months among ROS-1-positive NSCLC patients previously treated with ROS1 TKI and platinum-based chemotherapy (Cho et al., 2023).In the trial, the ROS1 TKInaïve group and the group previously treated with a ROS1 inhibitor demonstrated a verified overall response rate of 79% (95% CI: 68, 88) and 38% ORR (95% CI: 25, 52), respectively (FDA, 2023) 2 .
EGFR-TKIs mostly target the allosteric and ATP sites of EGFR, exerting ATP-compatible and/or irreversible action (Singh et al., 2023).EGFR mutations guide the EGFR-TKI development starting from Del19/L858R mutation to T79M (Singh et al., 2023).In 2003, gefitinib was approved by the FDA as the first EGFR-TKI for treating NSCLC, specifically targeting the Del19/L858R mutation (Cohen et al., 2004).The most recent FDAapproved EGFR-TKI for NSCLC is mobocertinib, which targets EGFR exon 20 insertion mutation (Markham, 2021).Osimertinib, a third-generation EGFR-TKI, targets the T79M mutation in patients sensitized to EGFR or those with resistance-associated mutations.However, resistance to osimertinib has also been reported (Gomatou et al., 2023).One potential approach to address EGFR drug resistance could involve therapies using antibodies against C797S mutation, which remains a challenge (Singh et al., 2023).Necitumumab is an example of an established EGFR monoclonal antibody for NSCLC.It blocks the ligand by binding to the extracellular domain III of EGFR (Dienstmann and Tabernero, 2010; Cai et al., 2020; NIH,  2023 1 ).In addition to EGFR antibodies, other antibodies developed and approved for NSCLC are listed in Table 1 (NIH, 2023) 1 .A broad range of antibodies, ranging from IgG monoclonal antibodies to antibody derivatives, antibody-drug conjugates, and immunocytokines bolster immune system functions by inhibiting cancer cell activity and eradicating cancer cells (Jin et al., 2022).Programmed death ligand 1 (PD-L1)-targeting antibodies, such as nivolumab and ipilimumab, were found to be effective for NSCLC.However, the need for further biomarkers for effective treatment has been highlighted (Hellmann et al., 2019;Chiang and Herbst, 2020).
Despite extensive utilization of TKIs in nonresistant cases, they are associated with numerous side effects, including cardiovascular side effects such as arrhythmia, QT prolongation, bradycardia, hypertension, myocardial infarction, PR interval prolongation, atrioventricular block, left ventricular dysfunction, edema, heart failure, arrhythmia, and pericardial effusion (Shyam Sunder et al., 2023).Additionally, new TKIs or other anticancer drugs are needed because of growing resistance to existing TKIs (Ferguson and Gray, 2018;Wang and Wang, 2021).A first-generation ALK-TKI crizotinib and a secondgeneration ALK-TKI ceritinib were reported to cause bradycardia as an adverse effect (Wang and Wang, 2021).Currently, an FDA-approved third-generation ALK-TKI, lorlatinib, is considered the gold standard for ALK-TKI treatment.Additionally, fourth-generation ALK-TKIs have started their phase studies.However, more molecular characterization is needed for new-generation ALK-TKIs to overcome resistance (Syed, 2019;Testa et al., 2023).
Despite the availability of active substances for the treatment of NSCLC, mortality rates remain for the disease due to several reasons, such as on-target and off-target resistance to TKIs and the absence of related biomarkers (De Mello et al., 2020;Mustachio and Roszik, 2020;Gomatou et al., 2023;Singh et al., 2023;Testa et al., 2023).As drug development for NSCLC is challenging, new therapeutic options are needed (De Mello et al., 2020;Gomatou et al., 2023;Testa et al., 2023).Drug repurposing could expedite the drug discovery process, offering a solution to the global burden of cancer, including NSCLC (Zhang et al., 2020;World Health Organization, 2021).

Repurposed drugs under clinical investigation for NSCLC
Drug repurposing in cancer provides a way to overcome drug development challenges, including low success rate of clinical studies, life-threatening side effects of approved drugs, and rapidly developed resistance mechanisms to approved drugs (Sleire et al., 2017).Anticancer drug development has the lowest approval rate after phase 1 (3.4%) compared to other drug development areas such as cardiovascular (25.5%), infectious (25.2%), and autoimmune (15.1%) diseases (Wong et al., 2019).Since drug repurposing eliminates pharmacokinetic uncertainty, anticancer drug development can benefit from this strategy (Sleire et al., 2017).
Repurposed drugs for NSCLC are currently undergoing clinical investigations.Studies exploring the treatment of NSCLC with repurposed drugs like nonsteroidal antiinflammatory drugs (NSAIDs), steroids, protease inhibitors, statins, antihyperglycemics, β-Blockers, antifungals, and antivirals have been conducted (clinicaltrials.gov)6 .Up-to-date clinical trials on repurposed drugs for NSCLC are presented in Table 2, while repurposed active substances from FDA orphan drugs and non-FDAapproved substances that are undergoing clinical trials for NSCLC are listed in Table 3 6 .Drugs listed in Table 2 are undergoing clinical trials for several purposes like decreasing morbidity, determining their potential efficacy after gaining a more detailed understanding of their biological effects, and investigating their ability to meet the need for new drugs due to resistance to existing medications in the NSCLC mechanism.
A life-threatening side effect of conventional NSCLC radiotherapy is cardiac morbidity, which may result in higher mortality for the patients (Donovan et al., 2023).An interventional phase 3 study (NCT04980716) conducted with NSCLC patients at risk of cardiac events after chemoradiotherapy utilizes statins to lower cardiac morbidity.This study, initiated in 2021, is currently in the recruitment phase and is expected to conclude in July 2026 (NCT04980716).
Another morbidity, venous thromboembolism (VTE), is associated with cancer, necessitating thromboprophylaxis after cancer progression (Weitz et al., 2020).A phase 3 clinical trial conducted between 2013 and 2016 investigated the efficacy and safety of nadroparin for thromboprophylaxis.However, the results of this trial have not been posted (NCT01980849).
Thromboprophylaxis was recommended for pancreatic cancer in 2019, but it was not recommended for lung cancer due to the high risk of bleeding (Farge et al., 2019).Finding a drug for thromboprophylaxis without the risk of bleeding remains a challenge for NSCLC patients.
Aspirin, a widely recognized nonselective cyclooxygenase (COX) inhibitor, was initially used as a pain killer before its use extended to the treatment of cardiovascular diseases, with dose adjustments made due to its antiinflammatory effect (Menter and Bresalier, 2023).Inflammation plays a significant role in cancerous tumor formation, and its mitigation could potentially diminish apoptotic and angiogenic cellular events (Menter and Bresalier, 2023).Prostaglandin E2 (PGE2) is a major instigator of inflammation and carcinogenesis, and aspirin has been shown to effectively reduce its levels (Menter and Bresalier, 2023).Lastly, aspirin has been repurposed for colorectal cancer, but its biological effects are not yet fully understood, and ongoing investigations are examining its potential efficacy in various other cancer types (Ricciotti and FitzGerald, 2021;Menter and Bresalier, 2023).In one such study, after NSCLC resection, 75 mg of aspirin was administered to decrease the mortality rate (NCT01058902).In another study, 350 mg of aspirin was administered to stage IIIb-IV or recurrent NSCLC patients to determine PGE2 biosynthesis inhibition (NCT01707823), but the study results are not posted.fusions (Piotrowska et al., 2018).This resistance can be overcome by reducing the phosphorylation of AKT and extracellular-signal-regulated kinase (ERK) (Piotrowska et al., 2018).Since aspirin reduces AKT phosphorylation, combination therapy of osimertinib and acetylsalicylic is under clinical trial (NCT03532698).
In another phase 2/3 clinical trial, a combinational therapy comprising EGFR-TKI (gefitinib), NSAID (acetylsalicylic acid), and a morning sickness drug (thalidomide) is being investigated to assess the impact of thalidomide on interleukin 2, but the results are not posted (NCT02387086).A combinational therapy of osimertinib with itraconazole (ITR) (NCT02157883) has also been suggested for NSCLC to overcome EGFR-TKI resistance (Vishwanathan et al., 2018).ITR is repurposed for several cancers including prostate, breast, triplenegative breast, ovarian, pancreatic, and lung cancer because of its anticancer properties (Antonarakis et al., 2013;Tsubamoto et al., 2015;Alhakamy and Md, 2019;Wu et al., 2022;Sinsuwan and Norchai, 2023).Besides hedgehog pathway inhibition, ITR's effect on multiple antiangiogenic pathways was reported in an early phase 1 NSCLC study (NCT02357836) (Gerber et al., 2020).The study also reports a change in energy metabolism via the TCA cycle and requirement for further studies (Gerber et al., 2020).In a phase 2 study (NCT00769600) conducted with 23 NSCLC patients, the combination of ITR with the chemotherapy agent pemetrexed resulted in a statistically significant overall survival rate of 32 months (Rudin et al., 2013).In another phase 2 study (NCT03664115), 60 NSCLC patients showed favorable outcomes following itraconazole treatment combined with chemotherapy, but the difference in overall survival rates was not deemed statistically significant (Mohamed et al., 2021).An alcohol addiction drug, disulfiram, has also been investigated in combination with chemotherapy in NSCLC patients, yielding a significantly high overall survival rate of 7.1 months (NCT00312819) (Nechushtan et al., 2015).

Nanoparticle-based drug delivery systems for oncology drugs
Nanotechnology is an application of nanoscience that provides unique properties to materials through fabrication and characterization on the nanoscale (Bayda  (Bayda et al., 2019).The utilization of nanotechnology in health sciences is termed nanomedicine, encompassing imaging, detection, and therapeutic drugs (Bayda et al., 2019).Within nanomedicine, cancer nanomedicine attracts attention because of the advances in cancer therapeutics facilitated through NP-based delivery systems (Bayda et al., 2019).NP-based drug delivery systems enhance drugs by prolonging drug circulation, reducing toxicity, enabling controlled and targeted drug delivery, and increasing the solubility of hydrophobic drugs (Dang and Guan, 2020).
The first FDA-approved NP-based drug was a liposomal doxorubicin commercialized as Doxil in 1995 (Patel, 1996).In Doxil, the pharmacokinetic profile of doxorubicin was enhanced by the liposomal drug delivery system which passively targets the tumor site via enhanced permeability and retention effect (EPR) because of its surface-grafted polyethylene glycol (PEG) chains, thereby prolonging drug circulation and providing longer vascular permeability (Barenholz, 2012).Doxil was used for treating metastatic breast cancer, Kaposi's sarcoma, multiple myeloma, and ovarian cancer (Barenholz, 2012).However, PEG on the surface of the liposome avoids the drugs from the reticuloendothelial system (RES) and cause drug accumulation in the tissues like the liver, spleen, and bone marrow (Barenholz, 2012).Since then, liposomes have been used as drug carriers for daunorubicin, cytrabine, cytarabine/daunorubicin, irinotecan, vincristine, mifamurtide MTP-PE, and doxorubicin (Giri et al., 2023).
Liposomes enhance the pharmacokinetics and biodistribution of drugs, prolong circulation time, reduce toxicity, and allow passive or active targeted therapy (Milano et al., 2022).Daunorubicin (DaunoXome; Gilead Sciences), cytarabine (DepoCyt; Pacira Pharmaceuticals), and a fixed combination of these drugs in liposome (Vyxeos; Celator/Jazz Pharma) were approved by FDA in 1996, 1999, and 2017, respectively. Daunorubicin (DaunoXome; Gilead Sciences) was approved for Kaposi's sarcoma.Delayed uptake of liposomes by RES was achieved using a daunoXomes composition of distearoyl phosphatidylcholine and cholesterol in a 2:1 ratio (Petre and Dittmer, 2007).Vyxeos (also known as CPX-351; Celator/Jazz Pharma) is the most recently approved NPbased cancer drug, approved in 2017 (Krauss et al., 2019).Vyxeos liposomal formulations have been introduced for the treatment of acute myeloid leukemia treatments (Krauss et al., 2019).Distearoyl phosphatidylcholine, distearoyl phosphatidylglycerol, and cholesterol are the compositions of the lipid membrane that encapsulates water-soluble drugs daunorubicin and cytarabine (Krauss et al., 2019).Liposome encapsulation not only provides sustained release in 24 h but also preserves drug/drug ratio (Krauss et al., 2019;Tardi et al., 2009).After encapsulation, the terminal half-life of free daunorubicin (18.5 h) and free cytarabine (10 h) was considered nearly similar (Krauss et al., 2019;Tardi et al., 2009).In 2012, liposomal vincristine (Marqibo; Talon Therapeutics/ Spectrum Pharmaceuticals) was approved for the treatment of Philadelphia chromosome-negative acute lymphoblastic leukemia; however, it was withdrawn in 2022 due to the lack of clinical benefit from postmarketing clinical trials (Silverman and Deitcher, 2013) 7 .Onivyde (also known as MM-398 or PEP02; Merrimack Pharma) is a liposomal formulation containing irinotecan used in the treatment of metastatic pancreatic cancer (Zhang, 2016).The rapid metabolism of irinotecan results in acute toxicity, but a liposomal formulation overcomes this problem by extending the circulation time of irinotecan (Milano et al., 2022).In addition to general pharmacokinetic improvement, liposomal encapsulation increases the tumor accumulation of irinotecan through the EPR effect (Milano et al., 2022).
A polymer-protein conjugate (Oncaspar; Enzon Pharmaceuticals) was approved in 2006 for acute lymphoblastic leukemia (Dinndorf et al., 2007).In this NPbased drug delivery system, the covalent conjugation of polyethylene glycol to L-asparaginase provides prolonged circulation time, resulting in reduced immunogenicity, which is the main drawback of free asparaginase (Dinndorf et al., 2007).
Commercially available FDA-approved microtubule inhibitor named paclitaxel albumin-stabilized nanoparticle formulation (Abraxane; Abraxis/Celgene) is used for treating metastatic breast cancer, adenocarcinoma of the pancreas, and NSCLC (Attwood, 2012;Attwood, 2013).Noncovalent hydrophobic interactions between human serum albumin-bound paclitaxel conjugates generate nanoparticles with a diameter of approximately 130 nm.This formulation reduces the toxicity (Desai, 2016).In a phase III trial for NSCLC, the overall response rate was 33%, which is considered significant.This therapy is now established as a first-line treatment option in combination with carboplatin for advanced or metastatic NSCLC (Socinski et al., 2012;Desai, 2016).

Nanoparticle-based drug delivery systems for NSCLC
NP-based drug delivery offers unique advantages for NSCLC therapies compared to free drugs by allowing for the use of different administration routes, generating different cellular responses via material adjustments, and enhancing drug efficacy (Babu et al., 2013;Mukherjee et al., 2019).Nanotechnology-based drug delivery approaches in lung cancer treatment can be expanded to encompass diverse administration routes, including oral, intravenous, and inhalation (Babu et al., 2013).For NSCLC therapeutics, polymeric nanoparticles are more suitable for systemic administration of the drugs and they are also studied for inhalation (Mukherjee et al., 2019).The inhalation route allows delivering higher drug concentrations the lungs and lower drug concentrations systemically, thereby providing a more localized therapy, with minimized adverse effects (Mukherjee et al., 2019).
Inhaled biopersistent nanoparticles and microparticles have different physicochemical properties (Kreyling et al., 2013).These properties can cause translocation in the circulatory system, and conjugation of nanoparticles with proteins could be a solution for this problem (Kreyling et al., 2013).NP-based drug delivery systems can reduce drugs side effects caused by systemic administration via intravenous routes (Mohtar et al., 2021).It also combats undesirable exhalation of low-inertia nanoparticles which is caused by simple pulmonary delivery of therapeutics (Sung et al., 2007).
A phase I study of DOTAP: Cholesterol-Fus1 Liposome Complex (DOTAP: Chol-fus1) (NCT00059605), a phase I-II study, DOTAP: Chol-TUSC2 (NCT01455389) combination with erlotinib, dexamethasone, and diphenhydramine, a phase I-II study of Manganese Superoxide Dismutase (MnSOD) Plasmid Liposome (NCT00618917) in combination with carboplatin, paclitaxel, and radiotherapy, and a phase I study of lurtotecan liposome (NCT00006036) combined with cisplatin are some of the examples of ongoing clinical trials exploring liposomal therapies for NSCLC.A silica core with an Au (gold) nanoshell, AuroLase, was administered to patients with primary and/or metastatic lung tumors via systemic intravenous infusion and activated at the target site externally with laser radiation delivered by optical fiber via bronchoscopy (NCT01679470).However, this approach is still under development (Singh et al., 2018).The delivery of therapeutic drugs via NP-based drug delivery systems for oncology drugs has exhibited promising efficacy in NSCLC treatment, aiming to regulate the growth of tumor cells (Sharma et al., 2019).

In vitro studies for repurposed drugs in nanoparticlebased drug delivery systems for NSCLC
The combination of both drug repurposing and NPbased drug delivery systems as a treatment strategy against NSCLC has gained growing interest recently.This combined strategy presents a solution to address the challenges associated with repurposed NSCLC drugs encountered in clinical applications, such as high toxicity, low efficiency, poor solubility, poor metabolism, and complex scaling-up requirements (Najlah et al., 2017;Alhakamy and Md, 2019;Parvathaneni et al., 2020a;Parvathaneni et al., 2020b).FDA-approved drugs repurposed and enhanced with a nanoparticle system for NSCLC in the literature with in vitro studies are listed in Table 4 (Najlah et al., 2017;Butcher et al., 2018;Alhakamy and Md, 2019;Alfaifi et al., 2020;Parvathaneni et al., 2020a;Parvathaneni et al.b, 2020;Liu et al., 2023).Among them, disulfiram, nelfinavir, itraconazole, and metformin were involved in clinical trials of repurposing for NSCLC (reported in Section 3), but they were not encapsulated in NP-based drug delivery systems.6.1.Disulfiram: disulfiram-loaded PLGA nanoparticles Antialcoholism drug disulfiram is metabolized in serum within 4 min which is sufficient for its antialcoholism efficacy (Najlah et al., 2017).However, rapidly metabolized disulfiram becomes a challenge for the drug's anticancer effect and this can be prevented by PLGA nanoparticles (Najlah et al., 2017).For a better anticancer effect, a copper (Cu)-dependent reaction should take place in the target tumor environment rather than in the bloodstream (Cen et al., 2004).
Disulfiram shows anticancer activity through Cu dependence on its thiuram structures (Butcher et al., 2018).Thiol groups of disulfiram should be chelated with Cu in a tumor environment to act as an anticancer agent via ROS generation-induced apoptosis.However, their chelation is blocked when the drug metabolizes orally, which this limits its anticancer applications (Butcher et al., 2018).Therefore, there is a need for an NP-based delivery system to protect the thiol groups of the drug for the treatment of NSCLC (Butcher et al., 2018).
For better penetration of the drug into the cancer tissue with the EPR effect, disulfiram PLGA nanoparticles require smaller particle sizes with larger surface area.These parameters can be applied during the emulsionsolvent evaporation method (Najlah et al., 2017).PLGA encapsulation enhances the drug's half-life from 3 min to 60 min (Najlah et al., 2017).6.2.Itraconazole: itraconazole-loaded chitosan-coated PLGA nanoparticles Poor solubility is a challenge for the antifungal drug ITR.For the treatment of NSCLC, ITR was encapsulated into PLGA nanoparticles via single-emulsion ultrasonication method and then coated with chitosan to overcome the solubility problem (Alhakamy and Md, 2019).The addition of chitosan enhances membrane permeability, while PLGA improves solubility.Overall, this formulation induces apoptosis and is suggested as an anticancer drug (Alhakamy and Md, 2019).

6.3.Nelfinavir: nelfinavir-loaded PLGA nanoparticles
Repurposing HIV protease inhibitor nelfinavir exhibited promising results for treating NSCLC; however, its use is limited by the toxicity associated with the required drug dosage (Parvathaneni et al., 2020a).Nelfinavir-PLGA nanoparticles were developed, with a size of 191.1 ± 10 nm, to enhance nelfinavir accumulation in cells while using lower doses (Parvathaneni et al., 2020a).The IC 50 value of the PLGA-encapsulated drug decreased to 8.3 ± 0.4 µM compared to the free drug, which had an IC 50 value of 18.1 ± 2.6 µM (Parvathaneni et al., 2020a).6.4.Febuxostat: febuxostat-loaded PEG-coated PLGA nanoparticles A xanthine oxidase inhibitor named febuxostat is utilized for the treatment of gout patients' hyperuricemia (Edwards, 2009).Febuxostat-loaded PEG-coated PLGA nanoparticles were synthesized with the nanoprecipitation method because of the poor water solubility of febuxostat (Alfaifi et al., 2020).After nanoparticle synthesis, the IC 50 value of the febuxostat-loaded nanoparticles decreased to 52.62 ± 2.52 µg/mL compared to the free drug, which had an IC 50 value of 68 ± 4.12 µg/mL (Alfaifi et al., 2020).6.5.Amodiaquine: amodiaquine-loaded PLGA nanoparticles Antimalarial drug hydroxychloroquine has been repurposed in a clinical trial for NSCLC (Section 3, NCT01026844, NCT04735068).Another antimalarial drug amodiaquine is a chloroquine analog with a similar mechanism of action except p53 stabilization (Espinoza et al., 2020).Amodiaquine has become a stronger anticancer candidate with an improved understanding of its mechanisms (Espinoza et al., 2020).The drug is considered an inhalation therapy against NSCLC, and it is delivered using amodiaquine-loaded PLGA nanoparticles (Parvathaneni et al., 2020b).The highpressure homogenization method is used to increase the  scale-up feasibility of nanoparticle systems and ensure reproducible product quality for the production of inhalable nanoparticulate systems (Parvathaneni et al., 2020b).6.6.Sertaconazole: hyaluronic acid-TPGS-sertaconazole nanoparticles Although the antifungal agent sertaconazole is not under clinical investigation for NSCLC, its repositioning potential has been reported, and the molecular mechanism of NSCLC cells has been revealed (Zhang et al., 2021).Sertaconazole triggers proapoptotic autophagy by preventing ubiquitination-mediated proteasomal degradation of TNF receptor type 1 associated death domain protein (TRADD) (Zhang et al., 2021).Moreover, microtubule depolymerization and binding of tubulin induced by sertaconazole cause toxicity in HeLa cells, which suggests the drug may have potential as an anticancer agent, warranting further studies (Sebastian and Rathinasamy, 2021).To reduce toxicity and increase the efficacy of sertaconazole, the thin film dispersion method was used in conjunction with hyaluronic acid and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) to provide CD44-specific, pH-responsive delivery, better solubility, and accumulation at the tumor site (Liu et al., 2023).To the best of our knowledge, this study has been the most recently reported combination strategy of both drug repurposing and NP-based drug delivery systems as a treatment against NSCLC (Liu et al., 2023).

Other nanotechnology-based therapies for NSCLC: vaccines
Cancer vaccines can be categorized into DNA, RNA, peptide, cell-based viral and bacterial vector vaccines (Fan et al., 2023b).These vaccines are being developed to overcome the primary challenge of generating antigenspecific T cell responses in cancer vaccines (Fan et al., 2023b).The application of mRNA vaccines has been accelerated by the COVID-19 pandemic.It's anticipated that the authorization of personalized mRNA vaccines for cancer will occur by 2030 (Fan et al., 2023b).However, in addition to mRNA vaccine challenges, DNA, peptide, cell-based viral and bacterial vector vaccines also have challenges that need to be addressed (Fan et al., 2023b).
To date, there is no available approved vaccine for lung cancer.However, with the increasing understanding of immunotherapies and advancements in nanotechnology, clinical trials have been conducted on several vaccine types including peptide vaccines.These clinical trials comprise vaccines against lung cancer, including peptidebased vaccines such as the MUC1 peptide-Poly-ICLC vaccine (NCT03300817, NCT01720836) and HLA-A*2402restricted URLC10, CDCA1, and KIF20A peptides vaccine (NCT01069575).

Conclusion and future perspectives
This review summarizes the current knowledge regarding NSCLC treatments, including existing approved drugs, drug repurposing with details of clinical study advances, and NP-based drug delivery systems.Additionally, it discusses the molecular aspects of the recently approved NSCLC drug, the ROS1 TKI repotrectinib, which was authorized in November 2023, alongside all other approved NSCLC drugs.However, resistance mechanisms in the NSCLC microenvironment occurs rapidly, primarily affecting detectable specific genes like EGFR and ALK (Liu et al., 2020), which necessitates personalized medicine approaches.The effectiveness of personalized medicine is high because of various genomic alterations in NSCLC as in the example of KRAS G12 (Jacobs et al., 2021).These specific genes serve as excellent targets for personalized medicine in NSCLC, highlighting a growing need for targeted therapies.While cancer nanomedicine enables targeted therapy, one of the main challenges is achieving drug release at the target area with the intended dose and timing (Fan et al., 2023a).High tumor accumulation, accurate subcellular localization, and efficient cellular internalization are additional obstacles in cancer nanomedicine (Fan et al., 2023a).Even though cellular internalization efficiency can be enhanced by targeted therapy, determining ligands without eliciting toxicity and immune responses and releasing only at the target cell remains challenging (Fan et al., 2023a).Further improvements in cancer nanomedicine could provide better solutions.In vitro studies of both drug repurposing and NP-based drug delivery systems as a treatment strategy against NSCLC are studied and further clinical experiments are required.Advances in NP-based drug delivery systems provide a promising resource for treatment options gained by the drug repurposing approach.The drug repurposing approaches are also improved with a new area of interest, artificial intelligence (AI), which is a rapidly growing technology area that can provide extensive information to target tumors' molecular profile and their microenvironment to predict expected adverse events, acquired or inherent resistance mechanisms, biomarkers, and the choice of combination therapy for personalized medicine.AI has been applied in oncology, specifically, in radiotherapy and immune-oncology (El Naqa et al., 2023)

Figure 1 .
Figure 1.Structure of the review.

Figure 3 .
Figure 3. Timeline for NP-based drug delivery systems for cancer treatment.(The NP for NSCLC is indicated with bold line).

Table 3 .
Repurposed active substances' on clinical trials for NSCLC (clinicaltrials.gov) 6.et al., 2019).It encompasses areas from physics, chemistry, and biology to material science, computer science, engineering, and health sciences

Table 4 .
In vitro studies of repurposed drugs in NP-based systems for NSCLC.
. These preapplications indicate that AI is a potential candidate bridging the gaps in detection, diagnosis, and therapeutics.has been supported by the Yıldız Technical University Scientific Research Projects Coordination Department.Project Number: FDK-2020-4086.Additionally, author Tuğba Gül İNCİ received a scholarship from the Republic of Türkiye, Council of Higher Education, 100/2000 Doctoral Scholarship Programme, in the field of microand nanotechnology.