Emergence and impact of theranostic‐nanoformulation of triple therapeutics for combination cancer therapy

Abstract Cancer remains a major global health threat necessitating the multipronged approaches for its prevention and management. Traditional approaches in the form of chemotherapy, surgery, and radiotherapy are often encountered with poor patient outcomes evidenced by high mortality and morbidity, compelling the need for precision medicine for cancer patients to enable personalized and targeted cancer treatment. There has been an emergence of smart multimodal theranostic nanoformulation for triple combination cancer therapy in the last few years, which dramatically enhances the overall safety of the nanoformulation for in vivo and potential clinical applications with minimal toxicity. However, it is imperative to gain insight into the limitations of this system in terms of clinical translation, cost‐effectiveness, accessibility, and multidisciplinary collaboration. This review paper aims to highlight and compare the impact of the recent theranostic nanoformulations of triple therapeutics in a single nanocarrier for effective management of cancer and provide a new dimension for diagnostic and treatment simultaneously.

][10][11] The number of new cases of cancer would likely increase at national and international levels due to the high prevalence and burden of modifiable risk factors, including obesity, sedentary lifestyle, poor eating habits, lack of exercise, and smoking. 127][28][29][30][31][32][33][34][35][36][37] However, each option has its own limitations.Chemotherapy comes with multi-drug resistance; RT damages the surrounding tissue limiting their applications and post-surgical treatment many patients are left with positive tumor margin and poor specificity.Immunotherapy, also known as biotherapy or biological response modifier therapy, is a path breaking treatment for cancer, wherein the body uses its own immune power to kill the cancer cells.Although IT is not suitable for all types of cancer, it can be used for certain types of cancer (lymphoma and leukemia), particularly the metastasis cancer, which didn't see any hopes for last many decades.Immunotherapy can be used as a single therapy for cancer treatment, or it can be used in combination with other treatment options such as surgery, chemotherapy, or RT.Immunotherapy, is an innovative cancer treatment in today's scenario with prolonged progression-free survival and overall survival; 38 however , it has certain uncertainties and may cause serious adverse reactions.][41][42][43][44] Theranostic is a term encompassing therapeutic and diagnostic imaging, coined by Funkhouser in 2002. 45,46heranostic includes delivering the drugs and imaging agents at the same time with a particular dosage aimed to monitor drug delivery and drug release, and achieve highest therapeutic efficacy. 47In pre-clinical models, real-time feedback on pharmacokinetics, drug targeting, and off-targeting of healthy organs have been reported in theranostic nanoformulations. 48][58][59][60][61][62][63][64] RT, for a long time, has been one of the primary treatment options for cancer; however, if given as the only treatment, it is not effective against the hypoxic tumor cells, causing a major setback on its own as a therapy.Thus, to enhance the RT efficacy, radio-therapeutic sensitizers need to be added during RT to improve oxygen concentration in tumor microenvironment (TME) [32][33][34]65 or RT to be combined with other therapeutic modalities (e.g., RT/photodynamic therapy [PDT] or RT/photothermal therapy [PTT]) to improve the treatment effectiveness. So of the reported radio-sensitizers based on nanoparticles (NPs) include gold (Au), tantalum oxide (TaOx), topological insulator bismuth selenide (Bi 2 Se 3 ), tungsten disulphide (WS 2 ), and polyoxometalates and have shown great results in RT efficacy.[66][67][68][69] Phototherapy administered in the form of PDT or PTT has great potential and is being employed as a therapy due to its minimally invasive effect and spatiotemporal selectivity.PDT similar to RT depends on photosensitizer (PS) for its maximum therapeutic efficacy by generating reactive oxygen species (ROS) 59,70 for example, singlet oxygen ( 1 O 2 ) leading to cancer cells death; however, hypoxic TME greatly narrows the scope of 1 O 2 .Furthermore, the higher concentration of oxygen during PDT may further inhibit the anti-tumor response.Other techniques such as

Key points
� Emerging theranostic nanoformulations of triple therapeutics cancer treatment are discussed.� Impact of theranostic nanoformulations of triple therapeutics for cancer management is reviewed.� Future outlook of current theranostic nanoformulations of triple therapeutics is highlighted.
high laser and prolonged PDT have been tested to overcome this issue, unfortunately it damages the normal tissue and hence limiting PDT application in clinical setting.Moreover, PDT is not effective for deep-seated tumor due to poor light penetration into deeper tissues.Therefore, an alternative approach is warranted to increase the therapeutic efficacy.In recent years, porphyrinic metal-organic based scaffold (PMOF) nanoparticles are established as next-generation PDT system with great potential.PMOF containing the porphyrins are dispersed to prevent self-quenching from PS aggregation and hence support the diffusion of photogenerated ROS and eventually enhance the PDT effect.In addition, these NPs can act as nanocarriers for encapsulating multiple therapeutic agents (antineoplastic drugs and photothermal reagents) to achieve synergism. 71On the other hand, PTT employs the use of heat produced from absorbed near-infrared rays to "cook" the most hypoxic tumor cells.Further, PTT-induced hyperthermia promotes the photosensitizer accumulation into tumor cells and increases oxygen supply in the tumor; hence, if combined with PDT and RT, it increases the effectiveness through a synergistic action, rather than PTT 57,58,72 alone, particularly for deep-seated tumor.Hence, combined photo and radiotherapy can be exploited as a very effective cancer treatment option by using each therapy advantage and remedy in overcoming the drawbacks. 67,68There are various imaging techniques such as photoacoustic (PA), PET, computerized tomography (CMT), 73,74 MR imaging, single photon emission computed tomography (SPECT), fluorescence imaging (FL) and two-photon excited fluorescence imaging, with different potential for providing information about the structural and functional aspect of an organ, are being currently used for biomedical and medical imaging [75][76][77] (features of the imaging modalities are compared in Table 1).
Although MR imaging demonstrates high spatial resolution into deeper structures, it is, however, not preferred in all the settings due to poor sensitivity to probes and high cost. 81,824][85][86][87] Fluorescence and bioluminescence are non-invasive, have high sensitivity to probes and provide multichannel imaging but do not provide high resolution and deeper level penetration.9][90][91][92] PA imaging, a noninvasive technique with high tissue penetration, and high resolution, however, has limited path length due to temperature sensitivity and weak absorption at shorter wavelengths. 63,93,94Nanodrug delivery systems can help in overcoming limitations related to imaging and provide more competent and high-quality imaging.The multicomponent theranostic systems can be efficiently combined within a specific nanoformulation system so that the conjugated nanoparticle can offer companionable theranostic modes.For instance, chemotherapy (chemotherapeutic drugs-loaded nanoparticles) can be combined with hyperthermia therapy to attain synergistic cancer therapy.Numerous strategies have been reported including combinatorial benefits of therapeutic agents with diagnostic tools to achieve significant results against the carcinogenic cells.The corresponding and coactive performances of these combinatorial strategies significantly enhance the outcomes and lay footing for more effective theranostic platforms.
This review represents and focuses on a recently designed and developed new class of theranostic nanoformulations of triple combination cancer therapy guided by single and/or multi-model imaging in a single nanocarrier to simultaneously diagnosis and treat cancer (Figure 1 illustrates components of theranostic nanoformulations and their encapsulation methods and Table 2 summarizes triple combination therapeutics with imaging and targeting [optionally] moiety, payload and their stimuli methods for efficient cancer treatment in pre-clinical studies).The combination of triple therapies (e.g., chemotherapy with photothermal and PDT, radiotherapy with phototherapy and PDT and immunotherapy with phototherapy and PDT or immunotherapy with chemotherapy and phototherapy) would combat the tumor recurrence and show anti-metastasis effects at very low doses with tumor targeting.In addition, imaging techniques not only provide the real-time observation of tumor site but also visualize drug distribution and measure therapeutic efficacy.In general, theranostic nanomedicine would improve the anti-tumor therapeutic efficacy through a synergistic effect.

| MECHANISM OF TUMOR TARGETING BY NANOFORMULATION
There are various nanoformulations and each uses a different targeting mechanism for drug delivery to tumor sites.Broadly, the nano-drug vehicles act at the tumor site by two mechanisms, namely active and passive targeting (Figure 2).In passive targeting, NFs are accumulated by exploiting the tumor site characteristics, majorly enhanced permeability and retention (EPR) effect in the TME.The highly porous vasculature of TME supports passive tumor targeting, which is based on the principle of diffusion improving drug efficacy and reducing systemic toxicity.However, the preferential accumulation of nanoformulations is reduced due to high interstitial fluid pressure and abnormality of TME.Hence, different nanocarriers may exploit the other properties of TME such as low pH, varying degree of enzymatic secretions, and higher redox potential for effective tumor targeting.

NANOFORMULATIONS FOR TRIPLE COMBINATION CANCER THERAPY
Numerous multimodal theranostic nanoformulations (presented in Table 2) have been designed and investigated and used to deliver a triple combination of therapies guided by imaging studies (which may vary from single to multiple imaging) in a single nanocarrier for the cancer treatment.95][96][97][98][99][100][101][102] They act in a synergistic manner to increase their therapeutics efficacy.Various theranostic nanoformulations of triple therapeutics are mentioned below in the subsections 3.1-3.3.

| Theranostic nanoformulations of chemotherapy, photothermal and photodynamic therapy for cancer therapy
This section describes the design and preparation of nanoformulation (namely biomimetic nanoparticle, hybrid nanoparticle and nanocapsule) of triple therapeutics (chemotherapy with other two therapies e.g., ) Pictorial illustration of the theranostic nanoformulation of triple therapeutics for combination cancer therapy: (A) Representation of synergistic multi-modal-theranostic nanoformulation and components in a single nanocarrier and application and mode of delivery (intravenous) of synergistic multi-modal-theranostic nanoformulation for cancer treatment.(B) Pictorial representation of delivery of three therapeutics with mono and/or multi-model imaging (optionally targeting) agents in a single nanocarrier: (I) Physical encapsulation: (a) all three therapeutics and imaging agent physically encapsulated simultaneously, (b) all the three therapeutics encapsulated with the help of non-covalent (electrostatic) interaction, (c) three therapeutics and imaging agent encapsulated by emulsion method, (d) therapeutics and imaging agents physically encapsulated one after other, (e) therapeutics and imaging agents physically encapsulated and targeting moiety by non-covalent interaction, (f) therapeutics and imaging agents physically encapsulated and targeting moiety attached by chemical conjugation, (g) therapeutics and imaging agents encapsulated by non-covalent interaction one after other followed by adsorption of the targeting agent on the surface of the nanocarrier.(II) Chemical conjugation: (a) firstly, one therapeutics conjugated to the nanocarrier material then other therapeutics/imaging physically encapsulated, (b) one therapeutics conjugated to the nanocarrier material followed by other therapeutic then imaging agents conjugated.physiological, and molecular information of tumor.Hence, this section highlights the emergence and impact of theranostic nanoformulation of triple therapeutics that showed potential combination cancer therapy.
A multifunctional nanoplatform of hollow porphyrinic (H-PMOF) with an inorganic mesoporous spherical shell was developed through a facile self-sacrificial ZIF-8 template.It had low dosage DOX and ICG (having drug loading capacity of 635%).Results demonstrated high tumor cell targeting and slower tumor growth in vivo. 71In another study, hollow mesoporous copper sulfide nanoparticles (HMCuS NPs) along with iron oxide nanoparticles (IONPs) containing Dox irradiated by NIR demonstrated enhanced effect of phototherapy and excellent antitumor therapeutic efficacy due to coupled plasmonic resonances. 95A theranostic nanoprobe containing hollow gold nanospheres (HAuNs), a triple combination of chemo, photothermal and PDT guided by activatable fluorescence for the diagnosis and treatment of cancer, demonstrated low nonspecific toxicity of photosensitizer and enhanced stability of the anticancer drug (Figure 3). 96 theranostic nanocomposite based on Gd doped-MSNs, DOX and ICG loaded thermosensitive liposome (DOX@GdMSNs-ICG-TSLs), guided by tri-modal imaging under NIR irradiation (Figure 4), appeared to be promising as a bridge for cancer treatment. 97ajendra kumar singh et al, attempted to develop a multicolor fluorescent bioglass nanoparticle (fBGn) with FL, two-photon (TP), and Raman imaging (RI), which demonstrated photothermal and photodynamic effects on cancer cells (Figure 5).The fBGn was effective in delivering pH-dependent DOX and hence, this multifunctional fBGn was found potentially useful for cancer theranostic. 98ei Guo et al., prepared TiO 2-x based theranostic system guided by bimodal imaging and NIR-triggered triple-therapy of CT/PTT/PDT, which showed the superiority of triple therapy in the inhibition and ablation of solid tumors, and B-mode ultrasonography confirmed the same findings through a liquefaction necrosis process (Figure 6). 69ang Z et al. designed and developed a smart nanocapsule (DOX-ICG@Fe/FeO-PPP) guided by dual-mode MRI and FI under NIR irradiation.The hallmark of this nanocapsule was effective circulation and high stability in the blood due to its large size in the beginning; NIR irradiation reduced and decomposed the size of tumor and help in controlled release of DOX.Fe/FeO helped in the overproduction of ROS for correcting hypoxia of tumor to manage the hypoxia-related resistance during chemo/photo and chemodynamic therapy.This NP subsequently proved to be highly effective as a therapeutic and diagnostic strategy and has a high potential for clinical translation of smart nanocapsule.   of 23

| Theranostic nanoformulations of radiotherapy with photothermal and photodynamic therapies for cancer therapy
This section briefly summarizes the relevant nanotheranostic studies related to the triple combination of radiotherapy, photothermal and PDT.
Wang J et al., engineered a multifunctional nanohybrid based on chlorin e6 (Ce6), polyaniline (PANI), HA and WS 2 nanodot (HA-WS2@PANI/Ce6) encompassing radio/ photothermal/photodynamic (RT/PTT/PDT) therapies via multi-modality guided imaging [fluorescence (FL), photoacoustic (PA), and computed tomography (CMT)] for cancer treatment.This nanohybrid had the core features of good dispersibility, NIR-region absorbance and large X-ray attenuation coefficient of tungsten, better ROS productivity and excellent biocompatibility, embarking its potential in combination therapy in the future.The findings revealed in vivo enhanced tumor uptake, improved tumor retention and diagnostic effect after intravenous injection, proving it to be a potential strategy for tumor treatment. 67nother theranostic nanoformulation, namely semiconductor heterojunction nanoparticles (SHNPs)-BiO-I@Bi 2 S 3 @BSA (bovine serum albumin) with a multifunctional theranostic nanoplatform for synergistic RT/PTT/PDT therapies via dual bioimaging of CMT/PA was designed.This radiosensitizer-based nanocomposite had fewer side effects and better outcome. 68

| Theranostic nanoformulations of immunotherapy in combination with chemotherapy and photothermal therapy for cancer treatment
This section briefly summarizes the relevant nanotheranostic studies and recent advances related to triple combination of IT, chemotherapy, and phototherapy for combination cancer therapy.
Chunhui et al. designed mitochondria targeted and NIR light-activatable multifunctional nanographene including triple punch of PDT, PTT, and immunotherapy.In addition, a new immunostimulatory conjugate DP-CpG was introduced.As a result, DP-CpG enhanced tumor immunogenicity due to the secretion of proinflammatory cytokines (e.g., IL-6, TNF, and IFN).The NIR laser and the photoactive nanocomplex demonstrated abundant ROS and tumor suppression rate of 88% with no adverse effects on mice (Figure 7). 100 A "Nano-targeted cells" with (4.18 mg DTX) and imiquimod-immune adjuvant (R837, 1.57 mg) loaded in Prussian blue 2.98 mg, photothermal transduction agents (PTAs)-in the core guided by bimodal PA-MR imaging demonstrated the combined effect of DTX and PTT in terms of in situ tumor eradication and immunotherapy enhanced the maturation rate of dendritic Cells by 4.34times compared to the control (Figure 8).Furthermore, the infiltration of cytotoxic T lymphocytes improved/ increased from 17.33% (control) to 35.5% leading to significant inhibition of primary tumor and metastasis. 101un Wei et al. 2019 developed a novel polypyrrole (PP) nanoparticle (PPy@CPT-HA-IRDye800CW) by conjugating a camptothecin (CPT)-HA shell using the near infrared dye IRDye800CW.Triple therapy of PTT, CT and IT was administered guided by FI and PA imaging.As a result, breast cancer was completely removed through an enhanced anti-tumor immune response with no metastasis or recurrence in mice bearing 4T1 tumor (Figure 9). 1023.3.1 | Summary of theranostic nanoformulations from Section 3 and its subsections Cancer nano-theranostic has been considered a promising and potential approach to provide reliable diagnosis and management.The field of clinical diagnosis has been extremely important in fighting against cancer as well as in assessing tumor progression and regression.4][115][116][117][118] The ideal multi-modality theranostic nanoformulations would be the those having enhanced tumor uptake, maximum biocompatibility, strong near infrared (NIR) absorbance, good dispersibility, greater ROS productivity, absent or minimal premature drug leakage, negligible multidrug resistance, absence of recurrence, zero probability of metastasis, remarkable cancer cell death, enhanced therapeutic efficacy and better prognosis.For instance, WS 2 nanodot uses high X-ray absorption coefficient of tungsten, HA helps in active tumor targeting, and PANI shell overcomes the limitations of WS 2 nanodot for radio-photodynamic-photothermal (RT/ PDT/PTT) therapies guided by FL/PA/CMT. 67Multimodality imaging is a better and comprehensive tool for theranostic.For instance, NIRF imaging has high sensitivity and PA is excellent in spatial resolution.Polypyrrole has higher biocompatibility and high efficiency for energy conversion and can be used to enhance tumor targeting effect as a photothermal agent. 102NIR light promotes CPT release in tumor by its F I G U R E 2 Mechanism for nanodrug delivery system mediated tumor targeting: Passive targeting occurs through the leaky vasculature surrounding the tumor tissues and active targeting occurs through the cross-interaction between the ligand/molecule on the surface of NFs and the overexpressed targeting receptors of the cell, that is, tumor cells.Figure produced using chemdraw software.

F I G U R E 3
Schematic representation of hollow gold nanosphere for local drug delivery system for fluorescence imaging with triple combination therapies (CT/PTT/PDT) with single light triggered strategy.Reproduced with permission. 96Copyright 2019, American Chemical Society.Figure re-produced using the chemdraw software.CT-chemotherapy, FRET-fluorescence resonance energy transfer (FRET), MMP2-matrix metalloproteinase-2, nm-nanometer, PDT-Photodynamic therapy, PTT-photothermal therapy.high PTT effect.In addition, the strong affinity and high specificity of HA and CD44 are considered to design a novel theranostic PPy@CPT-HA-combined with immunotherapy in the above cases.Immune check point blockers, when combined with PTT or chemotherapy, inhibit the recurrence and metastasis by inhibiting T cell activation and thus activating the immune response.This might prove to be an important alternative for the clinical management of solid tumor such as breast cancer.Research in the field of interaction between nanomaterials and x-rays is in its infancy, and effective radiosensitizers are still a challenge, especially one integrating with multiple treatment modalities.For instance, a photocatalytic semiconductor, Bismuth oxyiodide (BiOI), has been exploited as a radiosensitizer as it contains many high Z-elements, which can enhance the radiotherapeutic effect. 68In addition, BiOI act as an excited PS and produce highly reactive species to kill cancer cells as evident from above cases. 68The role of superparamagnetic IONPs has been exemplary as a gatekeeper modification in hollow mesoporous copper sulphide nanoparticles (HMCuS NP S ) to prevent the F I G U R E 4 Pictorial and schematic representation of Dox@GdMSNs-ICG-TSLs nanoformulation of triple combination therapies (CT/ PDT/PTT) with single light triggered guided by triple (FL/PA/MR) imaging: (A) preparation, (B) functions of Dox@GdMSNs-ICG-TSLs nanoformulation.Reproduced with permission. 97Copyright 2017, American Chemical Society.Figure re-produced using the chemdraw software.CTAB, cetyltrimethylammonium bromide; FA, folic acid; Gd 2 O 3 , gadolinium(III) oxide; ICG, indocyanine green; MSNs, mesoporous silica nanoparticles; NaOH, sodium hydroxide; NIR, near infrared; NIRF, near infrared fluorescence imaging and MRmagnetic resonance imaging; PA, photoacoustic imaging; PDT-Photodynamic therapy; PEG, poly(ethylene glycol); PTT, photothermal therapy; TEOS, tetraethyl orthosilicate.premature drug leakage application.Controlled ondemand drug release and higher photothermal effects have been demonstrated in a short time with minimal side effects in NIR-responsive HMCuS/DOX@IONP-PEG for chemo-phototherapy guided by MRI. 95dolinium (Gd) doped MSN nanocomposite showed promising findings as an attractive nano system along with exploitation of indocyanine Green (ICG) which can be used in near infrared fluorescence (NIRF) and PA and generate high ROS as well.ICG has a significant F I G U R E 5 Pictorial and schematic representation of hollow gold nanosphere for local drug delivery system for fluorescence imaging with triple combination therapies (PDT/CT/PTT) with single light triggered.(A) Development of DC-based bio glass (B) Mechanism of doxorubicin high loading and slow release and (C) drug delivery, tri-modal imaging and phototherapy.Reproduced with permission. 98Copyright 2020, American Chemical Society.Figure re-produced using the chemdraw software.APTES, (3-Aminopropyl) triethoxysilane; CD, carbon dots; FL, fluorescence imaging; PDT, photodynamic therapy; PTT, photothermal therapy; RI, Raman imaging; ROS, reactive oxygen species; TP, two photon imaging.role in the PDT and PTT effects, NIRF and PA. 97Carbon-dots (CD) can be exploited for multimodal imaging agents owing to their lower toxicity, light resistance, ease of functioning, tunable absorption emission spectra etc. 98 In addition, silica-based mesoporous bio glass having a high drug loading capacity, tunable pore size, excellent biocompatibility can be used to develop CDbased bio glass nanotheranostic carriers for targeted delivery, real-time monitoring, and phototherapy.Nanoparticles of the hydrogenated black titanium dioxide, which is not extensively explored for cancer treatment, were recently used for dual cancer imaging by FL/PA and NIR triggered CT/PDT/PTT. 69Similarly, TiO2-x sphere matrix can be used for extensive optical absorbance in the NIR region, producing hyperthermia and ROS after NIR irradiation. 69Overall, these theranostic-nanoformulations having a robust feature of drug incorporation, imaging movement, unique photosensitizer, PTT, and PDT activity help in implementing successful multi-modal theranostic in cancer treatment with an improved therapeutic index.These theranosticnanoformulations may help in better prognosis for the cancer patients, ultimately improve the biodistribution (in vivo) and have an accurate approach to visualize and monitor the therapeutics.

CHALLENGES OF NANOFORMULATION FOR CANCER TREATMENT
0][121][122][123][124][125][126] These NFs function as a smart, intelligent, and efficient nano-vehicle, containing active ingredients/drugs (single or combination of therapeutics) which travel throughout the human body (stay and available for longer time within the human body) and reach the target areas in respective diseases.However, poorly designed non-smart NFs lead and promote delivery to healthy cells and cause adverse drug reactions.In addition, considering the physiochemical properties (e.g., size, chemistry, and surface charge), these NFs would be modified to control the blood circulation and tissue penetration.For instance, positive F I G U R E 6 Pictorial and schematic representation of hollow gold nanosphere for local drug delivery system for fluorescence imaging with triple combination therapies (CT/PTT/PDT) with single light triggered.Reproduced with permission. 69Copyright 2017, American Chemical Society.Figure re-produced using the chemdraw software.Cy5.5, cyanine5.5;Dox, doxorubicin; NIR, near infrared; PA, photoacoustic imaging; PDT, photodynamic therapy; PTT, photothermal therapy; ROS, reactive oxygen species; TiO2, titanium dioxide.charge surface NFs reveal greater uptake than negative charge NFs due to the electrostatic interaction between the cell membrane and NFs.Our previous review described the combined cancer therapy (chemo and antiangiogenic therapies) in a single nanocarrier.These nanocarriers were made up of several organic, inorganic, or hybrid materials and the active drugs were entrapped with help of physical adsorption, encapsulation, and chemical conjugation strategies to co-deliver the two therapeutics in controlled drug release manner at target sites. 127These NFs demonstrated tumor growth inhibition, low drug resistance and overall improved treatment efficacy in mice models.
There are several nanoformulations which have been designed and investigated in the last 50 years (Figure 10 explaining the timeline and Table 3 represent the status of NFs for cancer treatment).][136][137] Despite the various advantages and the fact that nanoformulation (nanomedicine) is one of the most advanced methodologies in the creation of novel cancer therapies, very few nanocarriers-based cancer medicines have been successfully tested in humans and reached the market, for instance, Doxil® was the first FDA-approved nano-drug in year 1995.It has the advantages of prolonged drug circulation time and effective tumor targeting.It has been successfully used in various kinds of cancers, for instance, Kaposi sarcoma.However, its patent expired in 2010, and there has been no FDA-approved generic "Doxil" available since then.Other nanoformulations such as Abraxane® and DaunoXome® have shown improved therapeutic efficacy with low toxicity of the parent drug. 88,138Abraxane, also known as nab-paclitaxel (protein bound paclitaxel), has been used against pancreatic cancer, metastatic breast cancer, and non-small cell F I G U R E 7 Schematic diagram of the theranostic nanoformulations for cancer therapy.Reproduced under terms of the CC-BY license. 100Copyright 2021, The Authors, published by Springer Nature.Figure re-produced using the chemdraw software.DSPE-PEG, 1, 2distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol); dye-IR820, new indocyanine reen; TNF alpha, tumor necrosis factor alpha.

F I G U R E 8
Pictorial and schematic representation of hollow gold nanosphere for local drug delivery system for fluorescence imaging with triple combination therapies (IT/CT/PTT) with single light triggered.Reproduced with permission. 101Copyright 2018, American Chemical Society.Figure re-produced using the chemdraw software.CTL-tumor antigen-specific cytotoxic T lymphocyte; DTX, docetaxel; IL-10, interleukin 10; IL-6, interleukin 6; MR, magnetic resonance imaging; PA, photoacoustic imaging; PB NPs, prussian blue nanoparticles; PLGA, poly(lactic-co-glycolic acid); PTT, photothermal therapy; R837, imiquimod; TAM, tumor-associated macrophages; TNF, alpha-tumor necrosis factor alpha; w/o/w, water in oil-in-water emulsions methods.lung cancer as a first-line treatment.It has proven to be more effective than conventional paclitaxel-containing metastatic breast cancer patients and furthermore, patients need not undergo pre-medication to prevent any hypersensitivity reactions.For instance, Abraxane combined with gemcitabine has shown better patient survival than gemcitabine alone in patients with metastatic adenocarcinoma of the pancreas.Overall, on a risk-benefit analysis, the benefits of Abraxane are greater than its risks.
Similarly, polymer-paclitaxel conjugate is in Phase III trial and has low toxicity compared to free and parent paclitaxel. 89,90Similarly, FDA approved CPX-351, namely Vyxeos® (with cytarabine and daunorubicin ratio of 5:1), is used for the treatment of acute myeloid F I G U R E 9 Schematic illustration of triple combination therapies, including synergetic chemo-PTT in combination with immunotherapy guided by near-infrared FI and PA imaging.Reproduced under terms of the CC-BY license. 102Copyright 2019, The Authors, published by Elsevier.Figure reproduced using the Chemdraw software.A-PD-L1, anti-L1-antiprogrammed death-ligand 1; CD44, cell surface adhesion receptor; CPT, camptothecin; dye-IR820, new indocyanine green; FL, fluorescence imaging; HA, hyaluronic acid; Hyal, hyaluronidase enzyme; PTT, photothermal therapy.

RAJORA ET AL.
T A B L E 3 Current status of the nanoformulation (nanomedicine) for cancer therapy.leukemia. 91,139Likewise, a liposome-based nanoformulation with irinotecan and floxuridine is also reported to be in phase III for the treatment of advanced colorectal cancer. 140n today's time, the challenges exist in the form of designing a smart nanoformulation for successful clinical translation.This can be brought on by thorough assessment of the safety and toxicity profile of these smart nanoformulations.In addition, safety measures such as extensive pre-clinical evaluation, pharmacokinetics and pharmacodynamics, rigorous evaluation of smart nanoformulations for systemic toxicity, immunotoxicity, targeted toxicity, long-term safety, and compliance to regulatory bodies can build up a strong body of evidence.This would create a robust and dedicated system for this technological innovation.
The success rate of conventional monotherapy and combined therapy is very limited due to systemic toxicity.Additionally, these therapies have failed to maintain and deliver optimized drug dosages and have negligible efficacy.For instance, gemcitabine is used in metastatic breast cancer, however the median survival time is not prolonged in these patients.With nanotechnology advancement, polymeric nanoparticles of HA containing synergistic pairs of gemcitabine and imiquimod enhanced the anticancer activity. 141

OUTLOOK
This review has summarized the recent progress and impact in the field of synergistic triple combination cancer therapy guided by mono, dual and multi-modal imaging techniques in a single nanocarrier for precise cancer diagnosis and therapy.Various smart materials used for nanocarriers, such as WS 2 nanodot, HA, PANI shell, porphyrinic mesoporous shell, gold nanospheres, PEG etc. have been effectively used owing to their individual unique characteristics and compatibility with remarkable therapeutics.Cancer remains one of the most formidable challenges in modern medicine, necessitating innovative and multifaceted strategies for improved treatment outcomes.Traditional cancer therapies for cancer, such as chemo, radio, and surgery, often entail considerable side effects and limited specificity, underscoring the need for precision medicine approaches.In response to this imperative, the concept of theranostic has emerged as a transformative paradigm, integrating diagnostics and therapeutics within a single platform to enable personalized and targeted cancer management.
Theranostic nanoformulations represent a cuttingedge facet of this approach, offering a versatile toolkit to address the complexities of cancer treatment.These nanoformulations encapsulate therapeutic agents, such as chemotherapeutics or targeted therapies (PDT/PTT), alongside diagnostic components, typically imaging agents, or biomarkers.By combining diagnostics and therapeutics, theranostic nanoformulations hold the promise of optimizing cancer therapy in unprecedented ways.While the multimodality theranostic approach of cancer management based on novel nanoformulations presents a promising approach to cancer therapy and imaging, it's essential to acknowledge its limitations.In vivo biocompatibility, toxicity, target specificity, excretion after therapeutic/imaging function, clinical translation, cost, accessibility, and interdisciplinary collaborations are some of the important challenges to be addressed before successful clinical implementation of these multimodality treatment strategies using nanocarriers.Future research should focus on mitigating these limitations, optimizing the strategy, and conducting rigorous clinical trials to assess its safety and efficacy in real-world patient populations.In conclusion, above-mentioned theranostic nanoformulation in the field of synergistic triple combination cancer therapy guided by mono, dual and multimodal imaging techniques in a single nanocarrier serves for precise cancer medicine.Biological evaluations (In in vitro and in vivo) of these multimodal theranostic nanoformulations showed promising results and particularly in preclinical mice model with excellent antitumor efficiency and satisfactory imaging effects.Briefly, in vivo studies showed the improved tumor retention and tumor growth suppression with fewer adverse drug reactions and no tumor recurrence and metastasis.Based on these positive results, further exploration could be tested in other animals depending on the protocol and eventually among cancer patients for efficient cancer treatment. 142,143Although these multimodal theranostic nanoformulations exhibit specific characteristics of drug assimilation and shield, imaging activity, unique photosensitizer, photothermal and photodynamic activity with improved therapeutic efficacy and safety profile.However, cost-effectiveness needs to be weighed while designing and producing it for clinical use in the future for these theranostic nanoformulations.Nevertheless, there is still a long way to go to the market.Collectively, these multimodal-theranostic nanoformulations would serve as an ideal and potential nanoplatform for precise cancer treatment and hopefully would have clinical success in terms of patient outcome. 144,145oreover, the clinical success of cancer nanomedicine is very challenging, and the goal is to deliver adequate therapeutic to tumor and its associated microenvironment.Further studies are warranted for artificial intelligence (AI) driven physiologically based pharmacokinetics (PBPK) model to predict nanoformulation delivery to RAJORA ET AL. tumor in mice.It could serve as a platform for early screening with an aim to reduce the number of animal use.[148][149][150] AUTHOR CONTRIBUTIONS Hongbo Zhang and Amit Kumar Rajora conceived the idea; Amit Kumar Rajora, Eknath Damu Ahire, Manju Rajora and Sukhvir Singh wrote the paper.Amit Kumar Rajora, Manju Rajora, Jaydeep Bhattacharya and Hongbo Zhang reviewed and edited the paper.All authors have read and agreed to the current version of the manuscript.

F I G U R E 1 0
Timeline showing milestones in the design and development of nanoformulation (nanomedicine) for cancer diagnosis and treatment.Figure produced using chemdraw software.

T A B L E 1 A comparison of features of distinct imaging modalities for tumor diagnosis. Imaging techniques Type of imaging modality (source) Typical probes Resolution (sensitivity) Depth Time Pros Con Information (clinical use) Ref
T A