Precise Ratiometric Control of Dual Drugs through a Single Macromolecule for Combination Therapy

Innovative Nanoparticulate Strategies in Colon Cancer Treatment: A Paradigm Shift

As a major public health issue, colorectal cancer causes 9.4% of total cancer-related deaths and comprises 10% of new cancer diagnoses worldwide. In the year 2023, an estimated 153,020 people are expected to receive an identification of colorectal cancer (CRC), resulting in roughly 52,550 fatalities anticipated as a result of this illness. Among those impacted, approximately 19,550 cases and 3750 deaths are projected to occur in individuals under the age of 50. Irinotecan (IRN) is a compound derived from the chemical structure of camptothecin, a compound known for its action in inhibiting DNA topoisomerase I. It is employed in the treatment strategy for CRC therapies. Comprehensive in vivo and in vitro studies have robustly substantiated the anticancer efficacy of these compounds against colon cancer cell lines. Blending irinotecan in conjunction with other therapeutic cancer agents such as oxaliplatin, imiquimod, and 5 fluorouracil enhanced cytotoxicity and improved chemotherapeutic efficacy. Nevertheless, it is linked to certain serious complications and side effects. Utilizing nano-formulated prodrugs within "all-in-one" carrier-free self-assemblies presents an effective method to modify the pharmacokinetics and safety portfolio of cytotoxic chemotherapeutics. This review focuses on elucidating the mechanism of action, exploring synergistic effects, and innovating novel delivery approaches to enhance the therapeutic efficacy of irinotecan.

A technical note on emerging combination approach involved in the onconanotherapeutics

Cancer is the second cause of mortality worldwide, and the currently available conventional treatment approach is associated with serious side effects and poor clinical outcomes. Based on the outcome of the exploratory preclinical and clinical studies, it was found that therapeutic response increases multiple folds when anticancer drugs are used in combination. However, the conventional combination of anticancer drugs was associated with various limitations such as increased cost of treatment, systemic toxicity, drug resistance, and reduced pharmacokinetic attributes. Hence, attempts were made to formulate nanocarrier fabricated combinatorial drugs (NFCDs) to effectively manage and treat cancer. This approach offers several advantages, such as improved stability, lower drug exposure, targeted drug delivery, low side effects, and improved clinical outcome. Hence, in this review, first time, we have discussed the recent advancement and various types of nano carrier-based combinatorial drug delivery systems in a different type of cancer and highlighted the personalized combinatorial theranostic medicine as a futuristic anticancer treatment approach.

The effect of spacers in dual drug-polymer conjugates toward combination therapeutic efficacy

Recently, a great effort has been made to perfect the therapeutic effect of solid tumor, from single-agent therapy to combined therapy and many other polymer-drug conjugations with dual or more anticancer agents due to their promising synergistic effect and higher drug level accumulation towards tumor tissues. Different polymer-drug spacers present diverse therapeutic efficacy, therefore, finding an appropriate spacer is desirable. In this study, dual drugs that are doxorubicin (DOX) and mitomycin C (MMC) were conjugated onto a polymer carrier (xyloglucan) via various peptide or amide bonds, and a series of polymers drug conjugates were synthesized with different spacers and their effect on tumor treatment efficacy was studied both in vitro and in vivo. The result shows that the synergistic effect is better when using different linker to conjugate different drugs rather than using the same spacer to conjugate different drugs on the carrier. Particularly, the finding of this works suggested that, using peptide bond for MMC and amide bond for DOX to conjugate dual drugs onto single XG carrier could improve therapeutic effect and synergy effect. Therefore, in polymer-pharmaceutical formulations, the use of different spacers to optimize the design of existing drugs to enhance therapeutic effects is a promising strategy.

A dual macrophage polarizer conjugate for synergistic melanoma therapy

Tumor associated macrophages (TAMs) play a paradoxical role in the fate of aggressive tumors like melanoma. Immune modulation of TAMs from the tumor-permissive M2 phenotype to antitumoral M1 phenotype is an emerging attractive approach in melanoma therapy. Resiquimod is a TLR7/8 agonist that shifts the polarization of macrophages towards M1 phenotype. Bexarotene (BEX) is a retinoid that induce the expression of phagocytic receptors in macrophages besides its ability to downregulate the M2 polarization. However, the clinical use of both agents is hindered by poor pharmacokinetic properties. Here, for the first time we repurposed BEX based on its immunomodulatory properties and combined it with RES by designing hyaluronic acid (HA) conjugates of both drugs that act synergistically as a dual macrophage polarizer to promote the M1 phenotype and suppress the M2 phenotype. This combination enhanced the macrophage secretion of proinflammatory cytokines (IL-6 and TNF-α), while suppressing the production of tumor promoting cytokine CCL22. It enhanced the macrophage phagocytic ability and showed superior inhibitory effects against B16F10 cells. In vivo studies on a mouse melanoma model confirmed the superiority of the dual conjugate compared to the single HA-drug conjugates in suppressing the tumor growth. Immunoprofiling of the excised tumors revealed a significant increase in the M1/M2 ratio of TAMs in mice treated with the dual conjugate. Our intravenously injectable HA conjugate of RES and BEX provides a promising immunotherapeutic combination strategy for resetting the M1/M2 ratio, supporting the tumoricidal activity of TAMs for effective melanoma treatment.

Cross-linked (R)-(+)-lipoic acid nanoparticles with prodrug loading for synergistic cancer therapy

The nonspecific toxicity of loaded drugs and the side effect of carriers are two obstacles that hinder the clinical development of anticancer nanodrugs. Herein, we developed a new nanodrug 3-(methylthio)-propanoate camptothecin (Pro-CPT) loaded with cross-linked (R)-(+)-lipoic acid nanoparticles (Pro-CPT@cLANs). The Pro-CPT is a pH-responsive prodrug of camptothecin (CPT) that can effectively reduce the systemic toxicity of CPT caused by premature release. The cLANs are nanoparticles with structural homology to (R)-(+)-lipoic acid (LA) that hold not only LA-like biocompatibility but also LA-like anticancer activity, which may further relieve the toxicity of loaded drugs by reducing their dosages through synergistic effects and precise drug release at the tumor sites. According to in vitro data, the IC of Pro-CPT@cLANs against HT29 cells was 0.12 μM, ∼2.5 times lower than that of free Pro-CPT (0.3 μM); in vivo data showed that the tumor inhibition rate (TIR) and survival rate (SR) of Pro-CPT@cLANs against HT29 tumor-bearing nude mice were up to 85.1% and 80%, respectively, also far better than those of free CPT at the same dosage (TIR: 46%, SR: 0%). The Pro-CPT@cLANs provide a simple and efficient strategy to surmount the two obstacles in the development of nanodrugs and hold potential in clinical utility.

Recent Advances and Challenges in Controlling the Spatiotemporal Release of Combinatorial Anticancer Drugs from Nanoparticles

To overcome cancer, various chemotherapeutic studies are in progress; among these, studies on nano-formulated combinatorial drugs (NFCDs) are being actively pursued. NFCDs function via a fusion technology that includes a drug delivery system using nanoparticles as a carrier and a combinatorial drug therapy using two or more drugs. It not only includes the advantages of these two technologies, such as ensuring stability of drugs, selectively transporting drugs to cancer cells, and synergistic effects of two or more drugs, but also has the additional benefit of enabling the spatiotemporal and controlled release of drugs. This spatial and temporal drug release from NFCDs depends on the application of nanotechnology and the composition of the combination drug. In this review, recent advances and challenges in the control of spatiotemporal drug release from NFCDs are provided. To this end, the types of combinatorial drug release for various NFCDs are classified in terms of time and space, and the detailed programming techniques used for this are described. In addition, the advantages of the time and space differences in drug release in terms of anticancer efficacy are introduced in depth.

Ultrasound Combined with Core Cross-Linked Nanosystem for Enhancing Penetration of Doxorubicin Prodrug/Beta-Lapachone into Tumors

BACKGROUND

Nanosized drug delivery systems (NDDSs) have shown excellent prospects in tumor therapy. However, insufficient penetration of NDDSs has significantly impeded their development due to physiological instability and low passive penetration efficiency.

METHODS

Herein, we prepared a core cross-linked pullulan-modified nanosized system, fabricated by visible-light-induced diselenide bond cross-linked method for transporting β-Lapachone and doxorubicin prodrug (boronate-DOX, BDOX), to improve the physiological stability of the NDDSs for efficient passive accumulation in tumor blood vessels (β-Lapachone/BDOX-CCS). Additionally, ultrasound (US) was utilized to transfer β-Lapachone/BDOX-CCS around the tumor vessel in a relay style to penetrate the tumor interstitium. Subsequently, β-Lapachone enhanced ROS levels by overexpressing NQO1, resulting in the transformation of BDOX into DOX. DOX, together with abundant levels of ROS, achieved synergistic tumor therapy.

RESULTS

In vivo experiments demonstrated that ultrasound (US) + cross-linked nanosized drug delivery systems (β-Lapachone/BDOX-CCS) group showed ten times higher DOX accumulation in the tumor interstitium than the non-cross-linked (β-Lapachone/BDOX-NCS) group.

CONCLUSION

Thus, this strategy could be a promising method to achieve deep penetration of NDDSs into the tumor.

Polymer-drug conjugate therapeutics: advances, insights and prospects

Polymer-drug conjugates have long been a mainstay of the drug delivery field, with several conjugates successfully translated into clinical practice. The conjugation of therapeutic agents to polymeric carriers, such as polyethylene glycol, offers several advantages, including improved drug solubilization, prolonged circulation, reduced immunogenicity, controlled release and enhanced safety. In this Review, we discuss the rational design, physicochemical characteristics and recent advances in the development of different classes of polymer-drug conjugates, including polymer-protein and polymer-small-molecule drug conjugates, dendrimers, polymer nanoparticles and multifunctional systems. Current obstacles hampering the clinical translation of polymer-drug conjugate therapeutics and future prospects are also presented.

Ratiometric co-encapsulation and co-delivery of doxorubicin and paclitaxel by tumor-targeted lipodisks for combination therapy of breast cancer

Combination therapy is a promising treatment for certain advanced drug-resistant cancers. Although effective inhibition of various tumor cells was reported in vitro, combination treatment requires improvement in vivo due to uncontrolled ratiometric delivery. In this study, a tumor-targeting lipodisk nanoparticle formulation was developed for ratiometric loading and the transportation of two hydrophobic model drugs, doxorubicin (DOX) and paclitaxel (PTX), in one single platform. Furthermore, a slightly acidic pH-sensitive peptide (SAPSP) incorporated into lipodisks effectively enhanced the tumor-targeting and cell internalization. The obtained co-loaded lipodisks were approximately 30 nm with a pH-sensitive property. The ratiometric co-delivery of two drugs via lipodisks was confirmed in both the drug-resistant MCF-7/ADR cell line and its parental MCF-7 cell line in vitro, as well as in a tumor-bearing mouse model in vivo compared with a cocktail solution of free drugs. Co-loaded lipodisks exerted improved cytotoxicity to tumor cells in culture, particularly to drug-resistant tumor cells at synergistic drug ratios. In an in vivo xenograft mouse model, the anti-tumor ability of co-loaded lipodisks was evidenced by the remarkable inhibitory effect on tumor growth of either MCF-7 or MCF-7/ADR tumors, which may be attributed to the increased and ratiometric accumulation of both drugs in the tumor tissues. Therefore, tumor-specific lipodisks were crucial for the combination treatment of DOX and PTX to completely exert a synergistic anti-cancer effect. It is concluded that for co-loaded lipodisks, cytotoxicity data in vitro could be used to predict their inhibitory activity in vivo, potentially enhancing the clinical outcome of synergistic therapy.

Cell-penetrating peptide conjugates to enhance the antitumor effect of paclitaxel on drug-resistant lung cancer

To conquer the drug resistance of tumors and the poor solubility of paclitaxel (PTX), two PTX-cell-penetrating peptide conjugates (PTX-CPPs), PTX-TAT and PTX-LMWP, were synthesized and evaluated for the first time. Compared with free PTX, PTX-CPPs displayed significantly enhanced cellular uptake, elevated cell toxicity, increased cell apoptosis, and decreased mitochondrial membrane potential (Δψm) in both A549 and A549T cells. PTX-LMWP exhibited a stronger inhibitory effect than PTX-TAT in A549T cells. Analysis of cell-cycle distribution showed that PTX-LMWP influenced mitosis in drug-resistant A549T tumor cells via a different mechanism than PTX. PTX-CPPs were more efficient in inhibiting tumor growth in tumor-bearing mice than free PTX, which suggested their better in vivo antitumor efficacy. Hence, this study demonstrates that PTX-CPPs, particularly PTX-LMWP, have outstanding potential for inhibiting the growth of tumors and are a promising approach for treating lung cancer, especially drug-resistant lung cancer.

Ratiometric drug delivery using non-liposomal nanocarriers as an approach to increase efficacy and safety of combination chemotherapy

The observation that different drug ratios of the same drug combination can lead to synergistic or antagonistic effects when tested against the same cancer cell line in vitro gave rise to a new trend, the ratiometric delivery. This strategy consists of co-encapsulating a specific synergistic ratio of a drug combination into a nanocarrier so that synergism observed in vitro will be faithfully translated to in vivo, optimizing combination therapy. In this review we focus on how to quantify synergism in vitro, followed by how this affected the evolution of nanocarriers culminating in the ratiometric delivery, and finally we summarize the results of the non-liposomal formulations that were built upon this concept.

cRGD-installed docetaxel-loaded mertansine prodrug micelles: redox-triggered ratiometric dual drug release and targeted synergistic treatment of B16F10 melanoma

Combinatorial chemotherapy, which has emerged as a promising treatment modality for intractable cancers, is challenged by a lack of tumor-targeting, robust and ratiometric dual drug release systems. Here, docetaxel-loaded cRGD peptide-decorated redox-activable micellar mertansine prodrug (DTX-cRGD-MMP) was developed for targeted and synergistic treatment of B16F10 melanoma-bearing C57BL/6 mice. DTX-cRGD-MMP exhibited a small size of ca. 49 nm, high DTX and DM1 loading, low drug leakage under physiological conditions, with rapid release of both DTX and DM1 under a cytoplasmic reductive environment. Notably, MTT and flow cytometry assays showed that DTX-cRGD-MMP brought about a synergistic antitumor effect to B16F10 cancer cells, with a combination index of 0.37 and an IC₅₀ over 3- and 13-fold lower than cRGD-MMP (w/o DTX) and DTX-cRGD-Ms (w/o DM1) controls, respectively. In vivo studies revealed that DTX-cRGD-MMP had a long circulation time and a markedly improved accumulation in the B16F10 tumor compared with the non-targeting DTX-MMP control (9.15 versus 3.13% ID/g at 12 h post-injection). Interestingly, mice treated with DTX-cRGD-MMP showed almost complete growth inhibition of B16F10 melanoma, with tumor inhibition efficacy following an order of DTX-cRGD-MMP > DTX-MMP (w/o cRGD) > cRGD-MMP (w/o DTX) > DTX-cRGD-Ms (w/o DM1) > free DTX. Consequently, DTX-cRGD-MMP significantly improved the survival rates of B16F10 melanoma-bearing mice. Importantly, DTX-cRGD-MMP caused little adverse effects as revealed by mice body weights and histological analyses. The combination of two mitotic inhibitors, DTX and DM1, appears to be an interesting approach for effective cancer therapy.

Efficient co-delivery of immiscible hydrophilic/hydrophobic chemotherapeutics by lipid emulsions for improved treatment of cancer

Combinational nanomedicine is becoming a topic of much interest in cancer therapy, although its translation into the clinic remains extremely challenging. One of the main obstacles lies in the difficulty to efficiently co-deliver immiscible hydrophilic/hydrophobic drugs into tumor sites. The aim of this study was to develop co-loaded lipid emulsions (LEs) to co-deliver immiscible hydrophilic/hydrophobic drugs to improve cancer therapy and to explore the co-delivery abilities between co-loaded LEs and mixture formulation. Multiple oxaliplatin/irinotecan drug–phospholipid complexes (DPCs) were formulated. Co-loaded LEs were prepared using DPC technique to efficiently encapsulate both drugs. Co-loaded LEs exhibited uniform particle size distribution, desired stability and synchronous release profiles in both drugs. Co-loaded LEs demonstrated superior anti-tumor activity compared with the simple solution mixture and the mixture of single-loaded LEs. Furthermore, co-loaded nanocarriers could co-deliver both drugs into the same cells more efficiently and exhibited the optimized synergistic effect. These results indicate that co-loaded LEs could be a desired formulation for enhanced cancer therapy with potential application prospects. The comparison between co-loaded LEs and mixture formulation is significant for pharmaceutical designs aimed at co-delivery of multiple drugs.

Tumor-targeted polymeric nanostructured lipid carriers with precise ratiometric control over dual-drug loading for combination therapy in non-small-cell lung cancer

Gemcitabine (GEM) and paclitaxel (PTX) are effective combination anticancer agents against non-small-cell lung cancer (NSCLC). At the present time, a main challenge of combination treatment is the precision of control that will maximize the combined effects. Here, we report a novel method to load GEM (hydrophilic) and PTX (hydrophobic) into simplex tumor-targeted nanostructured lipid carriers (NLCs) for accurate control of the ratio of the two drugs. We covalently preconjugated the dual drugs through a hydrolyzable ester linker to form drug conjugates. N-acetyl-d-glucosamine (NAG) is a glucose receptor-targeting ligand. We added NAG to the formation of NAG-NLCs. In general, synthesis of poly(6-O-methacryloyl-d-galactopyranose)–GEM/PTX (PMAGP-GEM/PTX) conjugates was demonstrated, and NAG-NLCs were prepared using emulsification and solvent evaporation. NAG-NLCs displayed sphericity with an average diameter of 120.3±1.3 nm, a low polydispersity index of 0.233±0.04, and accurate ratiometric control over the two drugs. A cytotoxicity assay showed that the NAG-NLCs had better antitumor activity on NSCLC cells than normal cells. There was an optimal ratio of the two drugs, exhibiting the best cytotoxicity and combinatorial effects among all the formulations we tested. In comparison with both the free-drug combinations and separately nanopackaged drug conjugates, PMAGP-GEM/PTX NAG-NLCs (3:1) exhibited superior synergism. Flow cytometry and confocal laser scanning microscopy showed that NAG-NLCs exhibited higher uptake efficiency in A549 cells via glucose receptor-mediated endocytosis. This combinatorial delivery system settles problems with ratiometric coloading of hydrophilic and hydrophobic drugs for tumor-targeted combination therapy to achieve maximal anticancer efficacy in NSCLC.

Nanomedicine of synergistic drug combinations for cancer therapy - Strategies and perspectives

Nanomedicine of synergistic drug combinations has shown increasing significance in cancer therapy due to its promise in providing superior therapeutic benefits to the current drug combination therapy used in clinical practice. In this article, we will examine the rationale, principles, and advantages of applying nanocarriers to improve anticancer drug combination therapy, review the use of nanocarriers for delivery of a variety of combinations of different classes of anticancer agents including small molecule drugs and biologics, and discuss the challenges and future perspectives of the nanocarrier-based combination therapy. The goal of this review is to provide better understanding of this increasingly important new paradigm of cancer treatment and key considerations for rational design of nanomedicine of synergistic drug combinations for cancer therapy.

Development and evaluation of oxaliplatin and irinotecan co-loaded liposomes for enhanced colorectal cancer therapy

Drug combinations are widely employed in chemotherapy for colorectal cancer treatment. However, traditional cocktail combination in clinic causes the uncertainty of the treatment, owing to varying pharmacokinetics of different drugs. The aim of this study was to design co-loaded liposomes to achieve the synchronised delivery and release. Oxaliplatin and irinotecan hydrochloride, as one of recommended combination schemes for the treatment of colorectal cancer in clinic, were co-loaded into the liposomes. The particle sizes of the liposomes were <200nm with uniform size distribution. In vitro release study showed that both drugs could be synchronously released from the liposomes, which means the optimized synergistic ratio of two drugs could be achieved. In vitro cellular uptake revealed that co-loaded liposomes could efficiently deliver different drugs into the same cells, indicating their potential as carriers for enhancing the cancer therapy. CLSM images of cryo-sections for in vivo co-delivery study also revealed that co-loaded liposomes had superior ability to co-deliver both the cargoes into the same tumor cells. Besides, in vivo NIRF imaging indicated that the liposomes could increase the drug accumulation in tumor compared with free drug. In vitro cytotoxicity evaluation demonstrated that co-loaded liposomes exhibited higher cytotoxicity than the mixture of single loaded liposomes in both CT-26 and HCT-116 cells. Furthermore, co-loaded liposomes also presented superior anti-tumor activity in CT-26 bearing BALB/c mice. In vivo safety assessment demonstrated that liposomes had lower toxicities than their solution formulations. These results indicated that oxaliplatin and irinotecan hydrochloride co-loaded liposomes would be an efficient formulation for improving colorectal cancer therapy with potential clinical applications.

Xyloglucan as a mitomycin C carrier to reverse multidrug resistance

Hepatocellular carcinoma (HCC) is still considered as the third highest cause of cancer death in developing countries.

Targeted nanoparticles from xyloglucan–doxorubicin conjugate loaded with doxorubicin against drug resistance

The novel targeted Xyloglucan–doxorubicin nanoparticle drug delivery systems (DOX nano-DDSs) exhibited improved cellular uptake, increased accumulation in tumor, higher cytotoxicity against drug resistant tumor cells and reduced side effects.