Improved pharmacokinetics and efficacy of a highly stable nanoliposomal vinorelbine

Sphingomyelin-derived nanovesicles for the delivery of the IDO1 inhibitor epacadostat enhance metastatic and post-surgical melanoma immunotherapy

Epacadostat (EPA), the most advanced IDO1 inhibitor, in combination with PD-1 checkpoint inhibitor, has failed in a recent Phase III clinical trial for treating metastatic melanoma. Here we report an EPA nanovesicle therapeutic platform (Epacasome) based on chemically attaching EPA to sphingomyelin via an oxime-ester bond highly responsive to hydrolase cleavage. Via clathrin-mediated endocytosis, Epacasome displays higher cellular uptake and enhances IDO1 inhibition and T cell proliferation compared to free EPA. Epacasome shows improved pharmacokinetics and tumour accumulation with efficient intratumoural drug release and deep tumour penetration. Additionally, it outperforms free EPA for anticancer efficacy, potentiating PD-1 blockade with boosted cytotoxic T lymphocytes (CTLs) and reduced regulatory T cells and myeloid-derived suppressor cells responses in a B16-F10 melanoma model in female mice. By co-encapsulating immunogenic dacarbazine, Epacasome further enhances anti-tumor effects and immune responses through the upregulation of NKG2D-mediated CTLs and natural killer cells responses particularly when combined with the PD-1 inhibitor in the late-stage metastatic B16-F10-Luc2 model in female mice. Furthermore, this combination prevents tumour recurrence and prolongs mouse survival in a clinically relevant, post-surgical melanoma model in female mice. Epacasome demonstrates potential to synergize with PD-1 blockade for improved response to melanoma immunotherapy.

Harnessing immunotherapy to enhance the systemic anti-tumor effects of thermosensitive liposomes

Chemotherapy plays an important role in debulking tumors in advance of surgery and/or radiotherapy, tackling residual disease, and treating metastatic disease. In recent years many promising advanced drug delivery strategies have emerged that offer more targeted delivery approaches to chemotherapy treatment. For example, thermosensitive liposome-mediated drug delivery in combination with localized mild hyperthermia can increase local drug concentrations resulting in a reduction in systemic toxicity and an improvement in local disease control. However, the majority of solid tumor-associated deaths are due to metastatic spread. A therapeutic approach focused on a localized target area harbors the risk of overlooking and undertreating potential metastatic spread. Previous studies reported systemic, albeit limited, anti-tumor effects following treatment with thermosensitive liposomal chemotherapy and localized mild hyperthermia. This work explores the systemic treatment capabilities of a thermosensitive liposome formulation of the vinca alkaloid vinorelbine in combination with mild hyperthermia in an immunocompetent murine model of rhabdomyosarcoma. This treatment approach was found to be highly effective at heated, primary tumor sites. However, it demonstrated limited anti-tumor effects in secondary, distant tumors. As a result, the addition of immune checkpoint inhibition therapy was pursued to further enhance the systemic anti-tumor effect of this treatment approach. Once combined with immune checkpoint inhibition therapy, a significant improvement in systemic treatment capability was achieved. We believe this is one of the first studies to demonstrate that a triple combination of thermosensitive liposomes, localized mild hyperthermia, and immune checkpoint inhibition therapy can enhance the systemic treatment capabilities of thermosensitive liposomes.

Drug Stability and Minimized Acid-/Drug-Catalyzed Phospholipid Degradation in Liposomal Irinotecan

Therapeutics at or close to the nanoscale, such as liposomal irinotecan, offer significant promise for the treatment of solid tumors. Their potential advantage over the unencapsulated or free form of the drug is due in part to their altered biodistribution. For slow and sustained release, significant optimization of formulation is needed to achieve the required level of stability and allow long-term storage of the drug product. Gradient-based liposomal formulation of camptothecins such as irinotecan poses unique challenges owing to the camptothecin- and acid-catalyzed hydrolysis of phospholipid esters in the inner monolayer of the liposomal membrane. We demonstrated that a narrow set of conditions related to the external pH, temperature, intraliposomal concentration, identity of the drug-trapping agent, physical form of the drug inside the liposomes, and final drug load have a marked impact on the stability of the liposome phospholipid membrane. The physical form of the drug inside the liposome was shown to be an insoluble gel with an irinotecan-to-sulfate ratio approximating 1:1, reducing the potential for irinotecan-catalyzed phospholipid hydrolysis in the internal phospholipid monolayer. As a result of this work, a stable and active liposome formulation has been developed that maintains phospholipid chemical stability following long-term storage at 2-8°C.

Triggered release from thermosensitive liposomes improves tumor targeting of vinorelbine

Triggered drug delivery strategies have been shown to enhance drug accumulation at target diseased sites in comparison to administration of free drug. In particular, many studies have demonstrated improved targetability of chemotherapeutics when delivered via thermosensitive liposomes. However, most studies continue to focus on encapsulating doxorubicin while many other drugs would benefit from this targeted and localized delivery approach. The proposed study explores the therapeutic potential of a thermosensitive liposome formulation of the commonly used chemotherapy drug vinorelbine in combination with mild hyperthermia (39-43 °C) in a murine model of rhabdomyosarcoma. Rhabdomyosarcoma, the most common soft tissue sarcoma in children, is largely treated using conventional chemotherapy which is associated with significant adverse long-term sequelae. In this study, mild hyperthermia was pursued as a non-invasive, non-toxic means to improve the efficacy and safety profiles of vinorelbine. Thorough assessment of the pharmacokinetics, biodistribution, efficacy and toxicity of vinorelbine administered in the thermosensitive liposome formulation was compared to administration in a traditional, non-thermosensitive liposome formulation. This study shows the potential of an advanced formulation technology in combination with mild hyperthermia as a means to target an untargeted therapeutic agent and result in a significant improvement in its therapeutic index.

Chitosan-Coated Liposomes: The Strategy to Reduce Intestinal Toxicity and Improve Bioavailability of Oral Vinorelbine

In recent years, the oral administration of vinorelbine has gradually replaced intravenous administration in the treatment of several types of tumors. Even though the risk of phlebitis is avoided with oral administration, oral vinorelbine is still not a highly patient-compliant route due to the severe gastrointestinal toxicity. Vinorelbine-loaded liposomes with high encapsulation efficiency and suitable particle size were prepared using the ammonium sulfate gradient method. Chitosan-coated liposomes showed the slowest in vitro release compared to uncoated liposomes and vinorelbine solution. No damage was observed in the intestinal epithelial cells of mice orally administered with coated vinorelbine liposomes due to the low presence of the free drug in the gastrointestinal tract and the LD₅₀ was increased from 129.83 to 182.25 mg/kg compared to oral vinorelbine solution. In addition, the positive surface potential of chitosan-coating endowed liposomes with mucosal adhesive function, delaying the time to reach the peak plasma concentration of vinorelbine from 1 to 4 h after administration. And bioavailability was increased to 2.1-fold compared to vinorelbine solution. In short, a new strategy to address the severe gastrointestinal side effects of oral vinorelbine has been developed.

Dual Vinorelbine bitartrate and Resveratrol Loaded Polymeric Aqueous core Nanocapsules for Synergistic Efficacy in Breast Cancer

AIM

The current study focused on the development and evaluation of aqueous core nanocapsules (ACNs) as an effective carrier to deliver an optimal synergistic combination of a highly water soluble Vinorelbine bitartrate (VRL) and a poorly water-soluble Resveratrol (RES) for treatment of breast cancer.

METHODS

Various molar ratios of VRL to RES were screened against MCF-7 cell lines to determine the synergistic effects using Chou-Talalay method. Synergistic ratio of therapeutic agents was then incorporated into aqueous core nanocapsules utilizing a double emulsion solvent evaporation technique to yield dual drug loaded nanocapsules (dd-ACNs). The dd-ACNs were optimized using Box-Behnken design and characterized for physicochemical parameters such as particle size, zeta potential, polydispersity index, total drug content and encapsulation efficiency, surface morphology, drug excipient compatibility by FTIR and DSC, release kinetics, toxicity studies and anticancer efficacy (in-vitro and in-vivo).

RESULTS

Results demonstrated that the combination exhibited maximum synergy when higher doses of VRL were combined with smaller doses of RES (1:1, 5:1, and 10:1). The dual drug loaded ACNs were found to be stable and depicted a core-shell structure, narrow size range (150.2 ± 3.2 nm) with enhanced encapsulation (80% for VRL and 99% for RES). Moreover, the dd-ACNs were 5 times more efficacious in-vitro than a combination of free drugs, while reducing systemic toxicity. Also, pre-clinical evaluation of dd-ACNs also depicted drastic reduction of tumor volume as compared tp pristine VRL and physical combination of drugs.

CONCLUSION

The developed dd-ACNs can be applied as potential carrier for delivery of combination of chemotherapeutics at a synergistic ratio at tumor site.

Formulation optimization of an ephrin A2 targeted immunoliposome encapsulating reversibly modified taxane prodrugs

Ephrin A2 targeted immunoliposomes incorporating pH-sensitive taxane prodrugs were developed for sustained delivery of active drug to solid tumors. Here we describe the systematic formulation development and characterization of these immunoliposomes. We synthesized both paclitaxel and docetaxel prodrugs to formulate as ephrin A2-targeted liposomes stabilized in the aqueous core with sucroseoctasulfate (SOS). The optimized lipid formulation was comprised of egg-sphingomyelin, cholesterol, and polyethylene glycol distearoyl glycerol (PEG-DSG). The formulations examined had a high efficiency of prodrug encapsulation (as high as 114 mol% taxane per mole phospholipid) and subsequent stability (>3 years at 2-8 °C). The taxane prodrug was stabilized with extraliposomal citric acid and subsequently loaded into liposomes containing a gradient of SOS, resulting in highly stable SOS-drug complexes being formed inside the liposome. The internal prodrug and SOS concentrations were optimized for their impact on in vivo drug release and drug degradation. Cryo-electron microscope images revealed dense prodrug-SOS complex in the aqueous core of the immunoliposomes. Ephrin A2-targeted taxane liposomes exhibited sub-nanomolar (0.69 nM) apparent equilibrium dissociation constant toward the extracellular domain of the ephrin A2 receptor, long circulation half-life (8-12 h) in mouse plasma, a release rate dependent on intraliposomal drug concentration and stable long-term storage. At an equitoxic dose of 50 mg taxane/kg, ephrin A2-targeted liposomal prodrug showed greater antitumor activity than 10 mg/kg of docetaxel in A549 non-small cell lung, as well as MDA-MB-436 and SUM149 triple negative breast cancer xenograft models. The lead molecule entered a Phase I clinical trial in patients with solid tumors (NCT03076372).

Development of a stable single-vial liposomal formulation for vincristine

Background: Vincristine is a potent therapeutic agent with well-defined activity against hematologic malignancies and solid tumors. It is a cell-cycle specific drug with concentration and exposure duration dependent activity. When used by liposomal delivery, it exhibits enhanced anti-tumor activity. However, vincristine liposome formulation in the clinic is supplied as a 3-vial-kit due to lacking sufficient stability. So it has to be prepared in situ prior to use through a multi-step process.

Purpose: The purpose here is to develop a more stable and ready-to-use liposomal formulation for vincritstine in one vial.

Patients and methods: A series of preparations were investigated based on sphingomyelin/cholesterol/PEG2000-DSPE lipid composition, with different drug/lipid (D/L) ratios (1/10, 1/5, 1/2), using an active sucrose octasulfate triethylamine salt gradient loading method. In this work, compared to generic vincristine sulfate liposome injection (GVM), the stability both in vivo and in vitro and efficacy in vivo of novel vincristine liposomes were investigated.

Results: It was shown that the degradation of vincristine during 2–8°C storage was significantly decreased from 8.2% in 1 month (GVM) to 2.9% in 12 months (D/L ratio 1/5). The half-time for sphingomyelin/cholesterol/PEG2000-DSPE liposomes in vivo could be adjusted from 17.4 h (D/L ratio 1/10) to 22.7 h (D/L ratio 1/2) in rats, while the half-time for GVM was only 11.1 h. The increase in drug retention contributed to the lower in vivo toxicity. The antitumor efficacy was evaluated using a human melanoma tumor model and showed remarkable improvement compared to GVM.

Conclusion: The study demonstrates that the new formulation with the drug/lipid ratio of 1/5 owns a higher encapsulation efficiency, better stability, lower toxicity and superior antitumor efficacy, which is screened out for further development.

Heat-activated drug delivery increases tumor accumulation of synergistic chemotherapies

Doxorubicin is a clinically important anthracycline chemotherapeutic agent that is used to treat many cancers. Nanomedicine formulations including Doxil® and ThermoDox® have been developed to mitigate doxorubicin cardiotoxicity. Doxil is used clinically to treat ovarian cancer, AIDS-related Kaposi's sarcoma, and multiple myeloma, but there is evidence that therapeutic efficacy is hampered by lack of drug release. ThermoDox is a lipid-based heat-activated formulation of doxorubicin that relies on externally applied energy to increase tissue temperatures and efficiently trigger drug release, thereby affording therapeutic advantages compared to Doxil. However, elevating tissue temperatures is a complex treatment process requiring significant time, cost, and expertise compared to standard intravenous chemotherapy. This work endeavors to develop a companion therapeutic to ThermoDox that also relies on heat-triggered release in order to increase the therapeutic index of doxorubicin. To this end, a thermosensitive liposome formulation of the heat shock protein 90 inhibitor alvespimycin has been developed and characterized. This research demonstrates that both doxorubicin and alvespimycin are potent anti-cancer agents and that heat amplifies their cytotoxic effects. Furthermore, the two drugs are proven to act synergistically when cancer cells are treated with the drugs in combination. The formulation of alvespimycin was rationally designed to exhibit similar pharmacokinetics and drug release kinetics compared to ThermoDox, enabling the two drugs to be delivered to heated tumors at similar efficiencies resulting in control of a particular synergistic ratio of drugs. In vivo measurements demonstrated effective heat-mediated triggering of doxorubicin and alvespimycin release from thermosensitive liposomes within tumor vasculature. This treatment strategy resulted in a ~10-fold increase in drug concentration within tumors compared to free drug administered without tumor heating.

Encapsulation of epigallocatechin-3-gallate into albumin nanoparticles improves pharmacokinetic and bioavailability in rat model

In the present study, we fabricated epigallocatechin-3-gallate (EGCG) loaded albumin nanoparticles (Alb-NP-EGCG) to enhance bioavailability and improve pharmacokinetic parameters of EGCG. The physicochemical properties of the Alb-NP-EGCG were studied using scanning electron microscopy, differential scanning calorimetry, powder X-ray diffraction and in vitro release studies. Characterization of Alb-NP-EGCG indicated the formation of spherical nanoparticles with no drug and excipient interaction. Alb-NP-EGCG showed a high drug loading capacity of 92%. Further, in vitro study showed a sustained release of EGCG from Alb-NP-EGCG over a period of 48 h. Mathematical modeling and release kinetics indicated that the Alb-NP-EGCG followed zero order kinetic and EGCG was released via fickian diffusion method. In vivo bioavailability and distribution of Alb-NP-EGCG showed an enhanced plasma concentration of EGCG with 1.5 fold increase along with prolonged T 1/2 of 15.6 h in the system when compared with the free EGCG. All this study demonstrated the fabrication of EGCG loaded albumin nanoparticles which favored the slow and sustained release of EGCG with improved pharmacokinetics and bioavailability thereby prolonging the action of EGCG. Additional acute and sub-acute toxicity test of the Alb-NP-EGCG demonstrated the safety of the Alb-NP-EGCG. Therefore, the Alb-NP-EGCG could be a promising drug delivery system for EGCG.

Monitoring Tumor Response after Liposomal Doxorubicin in Combination with Liposomal Vinorelbine Treatment Using 3'-Deoxy-3'-[18F]Fluorothymidine PET

PURPOSE

Surgical resection is the standard treatment for localized colorectal cancer, which is the most common type of gastrointestinal cancer. However, over 40 % cases are diagnosed metastasized and apparently inoperable. Systemic chemotherapy provides an alternative to these patients. This study aims to evaluate the therapeutic potential of liposomal doxorubicin (lipoDox) in combination with liposomal vinorelbine (lipoVNB) in a CT-26 colon carcinoma-bearing mouse model.

PROCEDURES

The in vitro cytotoxicity of Dox and VNB on CT-26 cancer cells was determined by MTT and colony formation assays. Mice were subcutaneously inoculated with 2 × 10⁵ of CT-26 cells in the right hind flank. When tumor size reached 200 ± 50 mm³, mice were assigned to receive different treatment protocols. The pharmacokinetics, micro single-photon emission computed tomography/x-ray computed tomography imaging, biodistribution, and immunohistochemical staining studies were performed to survey the therapeutic efficacy of each regimen.

RESULTS

Based on the results of pharmacokinetic study, co-administration of lipoDox and lipoVNB did not affect their individual systemic distribution, while lipoDox retained longer in blood than lipoVNB did. Superior tumor growth retardation was observed in the group received lipoDox plus lipoVNB administration (1 mg/kg each, namely D₁V₁) than those injected with lipoDox plus VNB (1 mg/kg each, namely D₁fV₁). No severe side effects were detected in each group. The tumor-to-muscle ratio (T/M) derived from 3'-dexoy-3'-[¹⁸F]fluorothymidine ([¹⁸F]FLT) micro positron emission tomography (PET) images of D₁V₁- and D₁fV₁-treated mice and the controls on day 7 was 6.88 ± 0.54, 7.50 ± 0.84, and 9.87 ± 0.73, respectively, suggesting that D₁V₁ is a more efficacious regimen against CT-26 xenografts. The results of proliferating cell nuclear antigen (PCNA) immunohistochemical staining were consistent with those findings obtained from [¹⁸F]FLT microPET imaging.

CONCLUSION

This study demonstrated that lipoDox in combination with lipoVNB was more efficacious than clinically used regimen, lipoDox plus VNB, in the treatment of colon carcinoma and [¹⁸F]FLT-PET is a promising approach in monitoring the treatment outcome at early stage.

Liposomal Irinotecan Accumulates in Metastatic Lesions, Crosses the Blood-Tumor Barrier (BTB), and Prolongs Survival in an Experimental Model of Brain Metastases of Triple Negative Breast Cancer

PURPOSE

The blood-tumor barrier (BTB) limits irinotecan distribution in tumors of the central nervous system. However, given that the BTB has increased passive permeability we hypothesize that liposomal irinotecan would improve local exposure of irinotecan and its active metabolite SN-38 in brain metastases relative to conventional irinotecan due to enhanced-permeation and retention (EPR) effect.

METHODS

Female nude mice were intracardially or intracranially implanted with human brain seeking breast cancer cells (brain metastases of breast cancer model). Mice were administered vehicle, non-liposomal irinotecan (50 mg/kg), liposomal irinotecan (10 mg/kg and 50 mg/kg) intravenously starting on day 21. Drug accumulation, tumor burden, and survival were evaluated.

RESULTS

Liposomal irinotecan showed prolonged plasma drug exposure with mean residence time (MRT) of 17.7 ± 3.8 h for SN-38, whereas MRT was 3.67 ± 1.2 for non-liposomal irinotecan. Further, liposomal irinotecan accumulated in metastatic lesions and demonstrated prolonged exposure of SN-38 compared to non-liposomal irinotecan. Liposomal irinotecan achieved AUC values of 6883 ± 4149 ng-h/g for SN-38, whereas non-liposomal irinotecan showed significantly lower AUC values of 982 ± 256 ng-h/g for SN-38. Median survival for liposomal irinotecan was 50 days, increased from 37 days (p<0.05) for vehicle.

CONCLUSIONS

Liposomal irinotecan accumulates in brain metastases, acts as depot for sustained release of irinotecan and SN-38, which results in prolonged survival in preclinical model of breast cancer brain metastasis.

Facile construction of dual-targeting delivery system by using lipid capped polymer nanoparticles for anti-glioma therapy

A facile and reliable platform to construct dual targeting nanoparticles for glioma treatment, and the targeting efficiency was demonstrated.

Encapsulation of Nicardipine Hydrochloride and Release from Biodegradable Poly(D,L-lactic-co-glycolic acid) Microparticles by Double Emulsion Process: Effect of Emulsion Stability and Different Parameters on Drug Entrapment

Poly(D,L-lactic-co-glycolic acid) (PLGA) is an important material used in drug delivery when controlled release is required. The purpose of this research is to design and characterize PLGA microparticles (PLGA MPs) implants for the controlled release of nicardipine hydrochloride (NCH) in vitro. This study used the water-in-oil-in-water (w₁/o/w₂) double emulsion and solvent diffusion/evaporation approach to prepare PLGA MPs. Optimal processing conditions were found, such as polymer content, surfactant type, stabilizer concentration, inner and outer aqueous phase volumes, and stirring speed. The PLGA MPs for use as nicardipine hydrochloride (NCH) loading and release had spherical morphology, and the average diameter was smaller than 5.20 ± 0.25 μm. The release kinetics were modeled to elucidate the possible mechanism of drug release. In vitro release studies indicated that the NCH release rate is slow and continuous. PLGA MPs are an interesting alternative drug delivery system, especially for use with NCH for biomedical applications.

Lung Cancer-Targeting Peptides with Multi-subtype Indication for Combinational Drug Delivery and Molecular Imaging

Lung cancer is the leading cause of cancer-related death worldwide. Most targeted drugs approved for lung cancer treatment are tyrosine kinase inhibitors (TKIs) directed against EGFR or ALK, and are used mainly for adenocarcinoma. At present, there is no effective or tailored targeting agent for large cell carcinoma (LCC) or small cell lung cancer (SCLC). Therefore, we aimed to identify targeting peptides with diagnostic and therapeutic utility that possess broad subtype specificity for SCLC and non-small cell lung cancer (NSCLC). We performed phage display biopanning of H460 LCC cells to select broad-spectrum lung cancer-binding peptides, since LCC has recently been categorized as an undifferentiated tumor type within other histological subcategories of lung cancer. Three targeting phages (HPC1, HPC2, and HPC4) and their respective displayed peptides (HSP1, HSP2, and HSP4) were able to bind to both SCLC and NSCLC cell lines, as well as clinical specimens, but not to normal pneumonic tissues. In vivo optical imaging of phage homing and magnetic resonance imaging (MRI) of peptide-SPIONs revealed that HSP1 was the most favorable probe for multimodal molecular imaging. Using HSP1-SPION, the T2-weighted MR signal of H460 xenografts was decreased up to 42%. In contrast to the tight binding of HSP1 to cancer cell surfaces, HSP4 was preferentially endocytosed and intracellular drug delivery was thereby effected, significantly improving the therapeutic index of liposomal drug in vivo. Liposomal doxorubicin (LD) conjugated to HSP1, HSP2, or HSP4 had significantly greater therapeutic efficacy than non-targeting liposomal drugs in NSCLC (H460 and H1993) animal models. Combined therapy with an HSP4-conjugated stable formulation of liposomal vinorelbine (sLV) further improved median overall survival (131 vs. 84 days; P = 0.0248), even in aggressive A549 orthotopic models. Overall, these peptides have the potential to guide a wide variety of tailored theranostic agents for targeting therapeutics, non-invasive imaging, or clinical detection of SCLC and NSCLC.

Drug delivery systems and combination therapy by using vinca alkaloids

Developing new methods for chemotherapy drug delivery has become a topic of great concern. Vinca alkaloids are among the most widely used chemotherapy reagents for tumor therapy; however, their side effects are particularly problematic for many medical doctors. To reduce the toxicity and enhance the therapeutic efficiency of vinca alkaloids, many researchers have developed strategies such as using liposome-entrapped drugs, chemical- or peptide-modified drugs, polymeric packaging drugs, and chemotherapy drug combinations. This review mainly focuses on the development of a vinca alkaloid drug delivery system and the combination therapy. Five vinca alkaloids (eg, vincristine, vinblastine, vinorelbine, vindesine, and vinflunine) are reviewed.

A Simple and Improved Active Loading Method to Efficiently Encapsulate Staurosporine into Lipid-Based Nanoparticles for Enhanced Therapy of Multidrug Resistant Cancer

PURPOSE

This study was aimed at developing a new active loading method to stably encapsulate staurosporine (STS), a water insoluble drug, into lipid-based nanoparticles (LNPs) for drug targeting to tumors.

METHODS

A limited amount of DMSO was included during the active loading process to prevent precipitation and facilitate the loading of insoluble STS into the aqueous core of a LNP. The drug loading kinetics under various conditions was studied and the STS-LNPs were characterized by size, drug-to-lipid ratio, drug release kinetics and in vitro potency. The antitumor efficacy of the STS-LNPs was compared with free STS in a mouse model.

RESULTS

The drug loading efficiency reached 100% within 15 min of incubation at a drug-to-lipid ratio of 0.31 (mol) via an ammonium gradient. STS formed nano-aggregates inside the aqueous core of the LNPs and was stably retained upon storage and in the presence of serum. A 3-fold higher dose of the STS-LNPs could be tolerated by BALB/c mice compared with free STS, leading to nearly complete growth inhibition of a multidrug resistant breast tumor, while free STS only exhibited moderate activity.

CONCLUSION

This simple and efficient drug loading method produced a stable LNP formulation for STS that was effective for cancer treatment.

Aptamer density dependent cellular uptake of lipid-capped polymer nanoparticles for polyvalent targeted delivery of vinorelbine to cancer cells

In this work, MUC1 aptamer (designated S2.2) modified and vinorelbine (VRL) loaded lipid-polymer hybrid nanoparticles (Apt-VRL-NPs) were prepared.

A new lipid-based nano formulation of vinorelbine

Vinorelbine (VLB) is a semi-synthetic Vinca alkaloid which is currently used in treatment of different cancer types mainly advanced breast cancer (ABC) and advanced/metastatic non-small cell lung cancer (NSCLC). However, its marketed formulation has been reported to have serious side effects, such as granulocytopenia, which is the major dose-limiting toxicity. Other unwanted effects include venous discoloration and phlebitis proximal to the site of injection, as well as localized rashes and urticaria, blistering, and skin sloughing. Our long-term aim in synthesizing a novel nanomicellar vinorelbine formulation is to reduce or even eliminate these side effects and increase drug activity by formulating the drug in a lipid-based system as a nanomedicine targeted to the site of action. To this end, the purpose of this study was to prepare, characterize, and determine the in vitro efficacy of vinorelbine-loaded sterically stabilized, biocompatible, and biodegradable phospholipid nanomicelles (SSM; size, ∼15 nm). Our results indicated that vinorelbine incorporate at high quantities and within the interface between the core and palisade sections of the micelles. Incorporation ratio of drug within sterically stabilized micelles increased as the total amount of drug in the system increased, and no drug particles were formed at the highest drug concentrations tested. The nanomicellar formulation of vinorelbine was ∼6.7-fold more potent than vinorelbine dissolved in DMSO on MCF-7 cell line. Collectively, these data indicate that vinorelbine-loaded SSM can be developed as a new, safe, stable, and effective nanomedicine for the treatment of breast and lung cancers.

Pharmacokinetics, tumor accumulation and antitumor activity of nanoliposomal irinotecan following systemic treatment of intracranial tumors

AIM

We sought to evaluate nanoliposomal irinotecan as an intravenous treatment in an orthotopic brain tumor model.

MATERIALS & METHODS

Nanoliposomal irinotecan was administered intravenously in the intracranial U87MG brain tumor model in mice, and irinotecan and SN-38 levels were analyzed in malignant and normal tissues. Therapy studies were performed in comparison to free irinotecan and control treatments.

RESULTS

Tissue analysis demonstrated favorable properties for nanoliposomal irinotecan, including a 10.9-fold increase in tumor AUC for drug compared with free irinotecan and 35-fold selectivity for tumor versus normal tissue exposure. As a therapy for orthotopic brain tumors, nanoliposomal irinotecan showed a mean survival time of 54.2 versus 29.5 days for free irinotecan. A total of 33% of the animals receiving nanoliposomal irinotecan showed no residual tumor by study end compared with no survivors in the other groups.

CONCLUSION

Nanoliposomal irinotecan administered systemically provides significant pharmacologic advantages and may be an efficacious therapy for brain tumors.

Monitoring tumor response with [18F]FMAU in a sarcoma-bearing mouse model after liposomal vinorelbine treatment

OBJECTIVE

Previous studies have shown that the accumulation level of FMAU in tumor is proportional to its proliferation rate. This study demonstrated that 2'-deoxy-2'-[(18)F]fluoro-β-d-arabinofuranosyluracil ([(18)F]FMAU) is a promising PET probe for noninvasively monitoring the therapeutic efficacy of 6% PEGylated liposomal vinorelbine (lipo-VNB) in a subcutaneous murine NG4TL4 sarcoma mouse model.

METHODS

Female syngenic FVB/N mice were inoculated with NG4TL4 cells in the right flank. After tumor size reached 150 ± 50 mm(3) (day 0), lipo-VNB (5mg/kg) was intravenously administered on days 0, 3 and 6. To monitor the therapeutic efficacy of lipo-VNB, [(18)F]FMAU PET was employed to evaluate the proliferation rate of tumor, and it was compared with that observed from [(18)F]FDG/[(18)F]fluoroacetate PET. The expression of proliferating cell nuclear antigen (PCNA) in tumor during treatment was determined by semiquantitative analysis of immunohistochemical staining.

RESULTS

A significant inhibition (p<0.001) in tumor growth was observed on day 3 after a single dose treatment. The tumor-to-muscle ratio (T/M) derived from [(18)F]FMAU-PET images of lipo-VNB-treated group declined from 2.33 ± 0.16 to 1.26 ± 0.03 after three doses of treatment, while that of the control remained steady. The retarded proliferation rate of lipo-VNB-treated sarcoma was confirmed by PCNA immunohistochemistry staining. However, both [(18)F]FDG and [(18)F]fluoroacetate microPET imaging did not show significant difference in T/M between the therapeutic and the control groups throughout the entire experimental period.

CONCLUSION

Lipo-VNB can effectively impede the growth of NG4TL4 sarcoma. [(18)F]FMAU PET is an appropriate modality for early monitoring of the tumor response during the treatment course of lipo-VNB.

Building and characterizing antibody-targeted lipidic nanotherapeutics

Immunoliposomes provide a complementary, and in many instances advantageous, drug delivery strategy to antibody-drug conjugates. Their high carrying capacity of 20,000-150,000 drug molecules/liposome, allows for the use of a significantly broader range of moderate-to-high potency small molecule drugs when compared to the comparably few subnanomolar potency maytansinoid- and auristatin-based immunoconjugates. The multivalent display of 5-100 antibody fragments/liposome results in an avidity effect that can make use of even moderate affinity antibodies, as well as a cross-linking of cell surface receptors to induce the internalization required for intracellular drug release and subsequent activity. The underlying liposomal drug must be effectively engineered for long circulating pharmacokinetics and stable in vivo drug retention in order to allow for the drug to be efficiently delivered to the target tissue and take advantage of the site-specific bioavailability provided for by the targeting arm. In this chapter, we describe the rationale for engineering stable immunoliposome-based therapeutics, methods required for preparation of immunoliposomes, as well as for their physicochemical and in vivo characterization.

Sulfosalicylate mediates improved vinorelbine loading into LUVs and antineoplastic effects

Liposomal vinorelbine formulation is desirable, as it might improve the therapeutic activity of vinorelbine. However, because of its lipophilic and membrane-permeable properties, vinorelbine is hard to be formulated into liposomes using conventional drug-loading technologies. To improve vinorelbine retention, ammonium salts of several anionic agents were employed to prepare liposomal vinorelbine formulations. It was found that 5-sulfosalicylate (5ssa) could form stable complexes with vinorelbine and stabilize entrapped vinorelbine. The resultant vesicles had an in vitro release t(1/2) of ~12.49 hours in NH(3)-containing media, which is longer than those of sulfate and phytate vesicles (~0.57 hours). The circulation half-life of vinorelbine after the injection of 5ssa vesicles into normal mice was ~13.01 hours, accounting for ~2-fold increase relative to that of sulfate vesicles. Improved drug retention correlated with enhanced antitumor efficacy. In the RM-1/c57 model, 5ssa vesicles were more efficacious than sulfate vesicles (P < 0.05). In RM-1/BDF1 and Lewis lung cancer/c57 models, antitumor efficacy was also considerably improved after vinorelbine encapsulation into 5ssa vesicles. For instance, in the RM/BDF1 model, liposomal vinorelbine was at least 4-fold more therapeutically active than free vinorelbine. Our results demonstrated that 5ssa could stabilize vinorelbine relative to other anions, resulting in the formulation with improved drug retention and efficacy. Improved vinorelbine retention might be associated with the formation of insoluble precipitate, which could be proved by precipitation study and decreased drug-release rate at a high D/L ratio.

A phase I and pharmacokinetic study of liposomal vinorelbine in patients with advanced solid tumor

PURPOSE

This phase I study was performed to determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of an untargeted liposomal formulation of vinorelbine (NanoVNB®) and to characterize its plasma pharmacokinetics in patients with advanced solid tumors which were refractory to conventional treatment or without an effective treatment.

PATIENTS & METHODS

The study incorporated an accelerated titration design. Twenty-two patients with various solid tumors were enrolled. NanoVNB(®) was administered intravenously at doses of 2.2-23 mg/m(2) once every 14 days. Pharmacokinetic endpoints were evaluated in the first cycle. The safety profiles and anti-tumor effects of NanoVNB® were also determined.

RESULTS

Skin rash was the DLT and the most common non-hematological toxicity. The MTD was 18.5 mg/m(2). Drug-related grade 3-4 hematological toxicities were infrequent. Compared with intravenous free vinorelbine, NanoVNB® showed a high C(max) and low plasma clearance. Of the 11 patients completing at least 1 post-treatment tumor assessment, 5 had stable disease. No responders were noted.

CONCLUSION

NanoVNB® was well tolerated and exhibited more favorable pharmacokinetic profiles than free vinorelbine. Based on dose-limiting skin toxicity, further evaluation of NanoVNB® starting from 18.5 mg/m(2) as a single agent or in combination with other chemotherapeutic agents for vinorelbine-active malignancies is warranted.

Development of pegylated liposomal vinorelbine formulation using "post-insertion" technology

Prolonged vinorelbine exposure is correlated with improved antineoplastic effects, as evidenced by increased response rate in patients receiving continuous infusion. The administration of slow release pegylated liposomal vinorelbine formulation might mimic the pharmacokinetics of a continuous infusion, thus improving antitumor efficacy. But it is hard to prepare pegylated liposome vinorelbine using DSPE-PEG (an extensively used peglipid) because it could induce accelerated drug release. To resolve this problem, "post-insertion" technology was employed to prepare pegylated liposome vinorelbine formulations, which involved the incubation of vinorelbine-containing vesicles with DSPE-PEG micellar solutions. HPLC analysis revealed that after incubation at 60 degrees C for 60 min, approximately 100% DSPE-PEG could be inserted into the outer monolayer of the vesicles. Moreover, the grafting of peglipid did not induce the release of entrapped vinorelbine irrespective of intraliposomal anions. Drug release experiments indicated that "post-insertion" formulations were more able to retain entrapped drugs than "co-dissolving" formulations. The same phenomenon was observed when both series of formulations were injected in normal mice to compare pharmacokinetic profiles. In L1210 ascitic model, a "post-insertion" formulation with a PEG grafting density of approximately 0.5% exhibited the strongest antineoplastic effects, thus it was chosen to be further evaluated in S-180 and RM-1 models, in which the formulation was still more therapeutically active than conventional formulations. In conclusion, using "post-insertion" technology, the potential interaction between DSPE-PEG and vinorelbine could be prevented, thus making it possible to develop pegylated vinorelbine formulations.