Efficacy and tissue distribution of DHP107, an oral paclitaxel formulation

Novel solid self-emulsifying drug delivery system to enhance oral bioavailability of cabazitaxel

In this study, a novel cabazitaxel solid self-emulsifying drug delivery system (CTX S-SEDDS) was developed by solvent evaporation and liquid-solid compression technology, which overcame the limitations of the traditional SEDDS and improved the oral bioavailability. From the results of solubility, pseudo-ternary phase diagram, and single-factor analysis, Tween 80 (surfactant), Tricaprylin (oil), and Glyceryl monooleate (oil) with the ratio of 30:55:15 showed optimized particle size (140.87 nm), short emulsification and high cabazitaxel (CTX) loading capacity (50 mg·g-1). Based on the liquid-solid compression mathematical model, Syloid XDP3050 was determined as carrier material and Syloid 244FP as coating material. The prepared CTX S-SEDDS showed excellent flowability, tabletability, and reconstitution property. In vivo pharmacokinetics in rats demonstrated the absolute bioavailability of CTX S-SEDDS (17.27 %) was significantly enhanced compared with CTX solution (1.69 %), which was close to that of CTX-SEDSS (20.48 %). Lymphatic absorption was verified by in vitro imaging to be an important absorption route for self-emulsifying preparations. These results suggested that CTX S-SEDDS could enhance oral bioavailability of poorly water-soluble drug cabazitaxel while avoiding SEDDS limitations and harnessing the dual advantages of solid and liquid preparations.

Anti-cancer effects of DHP107 on canine mammary gland cancer examined through in-vitro and in-vivo mouse xenograft models

BACKGROUND

Canine mammary gland cancer (CMGC) is a common neoplasm in intact bitches. However, the benefit of adjuvant chemotherapy is unclear. The aim of this study was to investigate the anti-proliferative effects of paclitaxel on CMGC in in-vitro and in-vivo settings.

RESULTS

Paclitaxel dose-dependently inhibited viability and induced G2/M phase cell cycle arrest and apoptosis in both primary and metastatic CMGC cell lines (CIPp and CIPm). In animal experiments, the average tumour volume decreased significantly in proportion to the administered oral paclitaxel dose. By examining tumour tissue using a TUNEL assay and immunohistochemical staining with anti-CD31 as a marker of endothelial differentiation, respectively, it was confirmed that oral paclitaxel induced apoptosis and exerted an anti-angiogenetic effect in tumour tissues. Further, downregulation of cyclin D1 in tumour tissues suggested that oral paclitaxel induced cell cycle arrest in tumour tissues in-vivo.

CONCLUSIONS

Our results suggest that paclitaxel may have anti-cancer effects on CMGC through cell cycle arrest, induction of apoptosis, and anti-angiogenesis. This study could provide a novel approach to treat CMGC.

Beyond Formulation: Contributions of Nanotechnology for Translation of Anticancer Natural Products into New Drugs

Nature is the largest pharmacy in the world. Doxorubicin (DOX) and paclitaxel (PTX) are two examples of natural-product-derived drugs employed as first-line treatment of various cancer types due to their broad mechanisms of action. These drugs are marketed as conventional and nanotechnology-based formulations, which is quite curious since the research and development (R&D) course of nanoformulations are even more expensive and prone to failure than the conventional ones. Nonetheless, nanosystems are cost-effective and represent both novel and safer dosage forms with fewer side effects due to modification of pharmacokinetic properties and tissue targeting. In addition, nanotechnology-based drugs can contribute to dose modulation, reversion of multidrug resistance, and protection from degradation and early clearance; can influence the mechanism of action; and can enable drug administration by alternative routes and co-encapsulation of multiple active agents for combined chemotherapy. In this review, we discuss the contribution of nanotechnology as an enabling technology taking the clinical use of DOX and PTX as examples. We also present other nanoformulations approved for clinical practice containing different anticancer natural-product-derived drugs.

A phase Ib study of Oraxol (oral paclitaxel and encequidar) in patients with advanced malignancies

PURPOSE

Oraxol is an oral formulation of paclitaxel administered with a novel, minimally absorbed P-glycoprotein inhibitor encequidar (HM30181A). This phase Ib study was conducted to determine the maximum-tolerated dose (MTD) of Oraxol administered at a fixed dose for up to 5 consecutive days in patients with advanced malignancies.

METHODS

Part 1 of this study utilized a 3 + 3 dose-escalation design to determine the MTD of oral paclitaxel 270 mg plus oral encequidar 15 mg administered daily. Dose escalation was achieved by increasing the number of consecutive dosing days per week (from 2 to 5 days per week). Dosing occurred for 3 consecutive weeks out of a 4-week cycle. Part 2 treated additional patients at the MTD to determine tolerability and recommended phase II dose (RP2D). Adverse events, tumor responses, and pharmacokinetic profiles were assessed.

RESULTS

A total of 34 patients (n = 24 in Part 1, n = 10 in Part 2) received treatment. The MTD of Oraxol was determined to be 270 mg daily × 5 days per week per protocol definition and this was declared the RP2D. The most common treatment-related adverse events were fatigue, neutropenia, and nausea/vomiting. Hypersensitivity-type reactions were not observed. Of the 28 patients evaluable for response, 2 (7.1%) achieved partial response and 18 (64.3%) achieved stable disease. Pharmacokinetic analysis showed rapid absorption of paclitaxel when administered orally following encequidar. Paclitaxel daily exposure was comparable following 2-5 days dose levels.

CONCLUSION

The oral administration of encequidar with paclitaxel was safe, achieved clinically relevant paclitaxel levels, and showed evidence of anti-tumor activity.

Retrospective analysis of efficacy and safety of oral paclitaxel for treatment of various cancers in dogs (2017-2021)

Background

In humans, several safety evaluations have shown minimal adverse events with oral paclitaxel; however, its therapeutic efficacy and safety has not been well established in dogs with various cancers.

Objectives

We aimed to retrospectively evaluate the efficacy and safety of oral paclitaxel in dogs with various cancers.

Methods

Twenty‐one dogs diagnosed with various cancers were administered several doses of oral paclitaxel three times a month (group 1) or six times a month (group 2).

Results

The overall response rate was 6.25% (6.25%, complete response; 56.25%, stable disease; 37.5%, progressive disease) in dogs for which the treatment response could be evaluated. The median overall survival (OS) and progression‐free survival (PFS) were 74 and 60.5 days, respectively. Regardless of the administration group, differences in OS and PFS of the two groups did not reach statistical significance. Most dogs tolerated the treatment regimen well, and although minor adverse events were observed in some dogs, they recovered after temporary drug discontinuation, dose reduction or symptomatic treatment. There was no significant difference in the prevalence of adverse events between the two groups.

Conclusions

Based on the observed responses in certain types of cancers and the minimal adverse events, the study findings supported the efficacy and safety of oral paclitaxel administration in dogs. Thus, oral paclitaxel could play a role in the management of cancer in dogs.

Phase II study of DHP107 (oral paclitaxel) in the first-line treatment of HER2-negative recurrent or metastatic breast cancer (OPTIMAL study)

Background:

Standard intravenous (IV) paclitaxel is associated with hypersensitivity/toxicity. Alternative IV formulations have improved tolerability but still require frequent hospital visits and IV infusion. DHP107 is a novel oral formulation of paclitaxel that is approved in South Korea for the treatment of gastric cancer.

Methods:

This multicenter, phase II study using a Simon’s two-stage design investigated the efficacy and safety of DHP107 200 mg/m² administered orally twice daily on days 1, 8, and 15 every 4 weeks for the first-line treatment of recurrent or metastatic HER2-negative breast cancer.

Results:

Thirty-six patients were enrolled and 31 were assessable for efficacy. Patient median age was 57 years (range = 34–81) and 11 (31%) had triple-negative disease. A median of seven cycles (range = 1–28) of DHP107 was administered. Objective response rate was 55% (17 patients), all partial responses, according to the investigator’s decision and independent central review (ICR), and 44% (4/9 patients) in those with triple-negative disease. Disease control rate (partial response and stable disease) was 74% (23 patients) according to the investigator’s decision and ICR. In the intention-to-treat (ITT) population of all enrolled participants, the objective response rate was 50% (18/36 patients). Median progression-free survival was 8.9 months [95% confidence interval [CI]: 5.2–12.3) and median time to treatment failure was 8.0 months (95% CI: 4.2–10.0). DHP107 had an acceptable toxicity profile. All patients experienced treatment-emergent adverse events; the most common adverse events were decreased neutrophil count (81% all grades and 78% grade ⩾ 3) followed by peripheral sensory neuropathy (61% all grades and 8% grade 3). However, there was no febrile neutropenia or sepsis.

Conclusion:

DHP107 showed promising efficacy and acceptable tolerability in this phase II study and is currently being investigated in the OPTIMAL phase III study (NCT03315364).

Trial registration:

This trial was registered with ClinicalTrials.gov identifier: NCT03315364.

Microtubule-Interfering Drugs: Current and Future Roles in Epithelial Ovarian Cancer Treatment

Taxanes and epothilones are chemotherapeutic agents that ultimately lead to cell death through inhibition of normal microtubular function. This review summarizes the literature demonstrating their current use and potential promise as therapeutic agents in the treatment of epithelial ovarian cancer (EOC), as well as putative mechanisms of resistance. Historically, taxanes have become the standard of care in the front-line and recurrent treatment of epithelial ovarian cancer. In the past few years, epothilones (i.e., ixabepilone) have become of interest as they may retain activity in taxane-treated patients since they harbor several features that may overcome mechanisms of taxane resistance. Clinical data now support the use of ixabepilone in the treatment of platinum-resistant or refractory ovarian cancer. Clinical data strongly support the use of microtubule-interfering drugs alone or in combination in the treatment of epithelial ovarian cancer. Ongoing clinical trials will shed further light into the potential of making these drugs part of current standard practice.

Cubosomes: Versatile Nanosized Formulation for Efficient Delivery of Therapeutics

Cubosomes are bicontinuous cubic phase nanoparticles with a size range from 10-500 nm. They offer various advantages with some limitations at the production level, e.g., cubosomes have the feature to encapsulate a large amount of the drug due to its large internal area owing to cuboidal shape thus has a larger area but limited in large scale production due to its high viscosity which is associated with the problem in homogenization. This nanoparticulate formulation is compatible for administration by various routes like oral, transdermal, topical, buccal, etc. The drug release mechanism from cubosomes was reported to be dependent on the partition coefficient and diffusion process. Compared with liposomes, cubosomes show many differences in various aspects like shape, size, ingredients, and mode of action. The main ingredients for the preparation of cubosomes include lipids, stabilizer, aqueous phases, and therapeutic agents. Several methods have been reported for cubosomes, including the top-down method, the bottom-up method, and the adopted coarse method. For the optimization of cubosomes, the key factors to be considered, which will affect the cubosomes characteristics include; the concentration of lipid, temperature, and pH. At present, many research groups are exploring the potential of cubosomes as biosensors and nanocarriers. Based on the latest reports and research, this review illuminates the structure of the Cubosomes, mechanism of the drug release, different methods of preparation with factors affecting the cubosomes, application of cubosomes in different sectors, differences from the liposomes, and advantages.

Tissue pharmacokinetics of DHP107, a novel lipid-based oral formulation of paclitaxel, in mice and patients by positron emission tomography

DHP107 is a newly developed lipid‐based oral formulation of paclitaxel. We evaluated the in vivo tissue pharmacokinetics (PKs) of DHP107 in mice and patients using positron emission tomography (PET). Radioisotope‐labeled [³H]DHP107 and [¹⁸F]DHP107 for oral administration were formulated in the same manner as the manufacturing process of DHP107. In vivo tissue PK were assessed in healthy ICR mice and breast cancer xenografted SCID mice. Two patients with metastatic breast cancer were clinically evaluated for absorption at the target lesion after internal absorbed dose estimation. Whole‐body PET/computed tomography data were acquired in healthy and xenografted mice and in patients up to 10–24 h after administration. Tissue [¹⁸F]DHP107 signals were plotted against time and PK parameters were determined. The amounts of radioactivity in various organs and excreta were determined using a beta‐counter and are expressed as the percentage of injected dose (ID). Oral [¹⁸F]DHP107 was well‐absorbed and reached the target lesion in mice and patients with breast cancer. Significant amounts of radioactivity were found in the stomach, intestine, and liver after oral administration of [³H]‐ and [¹⁸F]DHP107 in healthy mice. The [¹⁸F]DHP107 reached a peak distribution of 0.7–0.8%ID in the tumor at 5.6–7.3 h in the xenograft model. The [¹⁸F]DHP107 distribution in patients with metastatic breast cancer was the highest at 3–4 h postadministration. Systemic exposures after administration of a DHP107 therapeutic dose were comparable with those in previous studies. PET using radioisotope‐labeled drug candidates is useful for drug development and can provide valuable information that can complement plasma PK data, particularly in early phase clinical trials.

Dual Formulation and Interaction Strategies to Enhance the Oral Bioavailability of Paclitaxel

A self-microemulsifying drug delivery system (SMEDDS) was developed to enhance Paclitaxel (PTX) solubility and membrane permeability, thus improve its bioavailability. Pre-formulation studies were performed to optimize PTX-SMEDDS formulation. Then, in vitro characteristics of the formulation were determined and PTX oral absorption was investigated in rabbits. The optimized PTX-SMEDDS showed emulsification time of 31 ± 4 s, droplet size of 19.4 ± 0.5 nm, poly-dispersibility index of 0.35 ± 0.08, percentage transmittance after dilution of 99 ± 0.02%, zeta potential of 36.82 ± 1.8 mv, cloud point of 78 ± 0.5 °C and infinite dilution capability. The formulation maintained its physical and chemical stability during storage at 4 °C for three months. Oral administration of 10 mg/kg of 1.5% w/w PTX-loaded SMEDDS to rabbits increased PTX bioavailability by 4.5 fold in comparison to untreated PTX suspension. While when the rabbits received 1.5% w/w PTX-loaded SMEDDS after pretreated with 1 dose and 2 doses of cyclosporine A, PTX bioavailability increased by 4.4 and 7.8 fold, respectively. This indicates that the combined effect of the SMEDDS formulation in addition to pretreatment with P-gp and CYP3A4 inhibitor, can improve the oral bioavailability of poorly soluble and poorly permeable drugs such as PTX in rabbits.

Enhanced absorption, and efficacy of oral self-assembled paclitaxel nanocochleates in multi-drug resistant colon cancer

Chemotherapy in drug-resistant cancers remains a challenge. Owing to associated poor bioavailability, oral administration of hydrophobic anticancer drugs like paclitaxel has been quite challenging, with the scenario being further complicated by Pgp efflux in drug-resistant tumours. We developed a novel nanocochleates (CPT) system encapsulating paclitaxel (PTX) to treat resistant colon cancer by oral administration. PTX encapsulated nanocochleates (PTX-CPT), made up of phosphatidylserine in size range of 350-600 nm with -20 ± 5.2 mV zeta potential were protected from degradation at acidic gastric pH and showed sustained PTX release over 48 h under intestinal pH condition. In vitro cytotoxicity studies on HCT-116 & HCT-15 cells (multi-drug resistant) established IC50 value of <10 and 69 nM, respectively, which was significantly lower when compared to commercial Taxol formulation. Further, the in vivo efficacy with five oral doses of 30 mg/kg PTX-CPT in an HCT-15 drug-resistant colon cancer xenograft mouse model showed more than 25 fold reduction in the tumour growth inhibition as compared to intravenous Taxol which showed just 1.94% inhibition. Interestingly, PTX-CPT treated mice also showed significantly lower proliferation index and microvessel density when compared to Taxol treated mice. Nanocochleates showed lower toxicity with at LD-50 value greater than 300 mg/kg as described in OECD 423 guideline. The enhanced efficacy of PTX-CPT speculated due to its internalization by active endocytosis, ability to escape Pgp efflux, and due to a combined effect of the pro-apoptotic and antiangiogenic role. Taken together, the results suggested the PTX-CPT a promising strategy for efficiently treating drug-resistant colon cancer orally.

Liposomes for Enhanced Bioavailability of Water-Insoluble Drugs: In Vivo Evidence and Recent Approaches

It has been known that a considerable number of drugs in clinical use or under development are water-insoluble drugs with poor bioavailability (BA). The liposomal delivery system has drawn attention as one of the noteworthy approaches to increase dissolution and subsequently absorption in the gastrointestinal (GI) tract because of its biocompatibility and ability to encapsulate hydrophobic molecules in the lipid domain. However, there have been several drawbacks, such as structural instability in the GI tract and poor permeability across intestinal epithelia because of its relatively large size. In addition, there have been no liposomal formulations approved for oral use to date, despite the success of parenteral liposomes. Nevertheless, liposomal oral delivery has resurged with the rapid increase of published studies in the last decade. However, it is discouraging that most of this research has been in vitro studies only and there have not been many water-insoluble drugs with in vivo data. The present review focused on the in vivo evidence for the improved BA of water-insoluble drugs using liposomes to resolve doubts raised concerning liposomal oral delivery and attempted to provide insight by highlighting the approaches used for in vivo achievements.

DHP23002 as a next generation oral paclitaxel formulation for pancreatic cancer therapy

OBJECTIVE

This study aimed to develop a new oral paclitaxel formulation (DHP23002) and to evaluate its absorption and antitumor effects in a pancreatic tumor mouse model.

METHODS

To investigate the oral absorption of DHP23002, a newly developed lipid-based orally active paclitaxel formulation, a pharmacokinetic study of DHP23002, was conducted in mice (62.5 and 125 mg/kg). Moreover, to evaluate the antitumor effect of DHP23002 in pancreatic cancer treatment, the drug was administered to female athymic nude mice at 0 (vehicle), 25, 62.5, and 125 mg/kg on alternate days; the efficacy of the agent was compared with the efficacy of intravenous Taxol® injections at 10 mg/kg once per week. After 3 weeks of administration, tumor growth in mice belonging to each group was further monitored for 4 weeks after discontinuing medication. Moreover, to examine paclitaxel (DHP23002) accumulation in the tumor tissue, the amount of paclitaxel in tumor/blood was quantified using liquid chromatography with quadruple-TOF mass spectrometry.

RESULTS

In the mouse pharmacokinetic study, oral Taxol® showed a negligible absorption, whereas DHP23002 showed a high absorption rate dependent on dosage, with a bioavailability of approximately 40% at a dose of 62.5 mg/kg. In efficacy-related studies, DHP23002 administration at a dose of 25, 62.5, or 125 mg/kg on alternate days for 3 weeks showed a superior tumor inhibitory effect of 80%, 92%, and 97% in a xenograft mouse model, respectively, after 7 weeks. Paclitaxel accumulation in tumors persisted for >24 h in mice, when orally administered once at doses of 25, 62.5, and 125 mg/kg DHP23002.

CONCLUSION

Oral chemotherapy with DHP23002 showed excellent absorption in animals owing to a strong antitumor activity in a pancreatic cancer mouse model. This demonstrates that paclitaxel is largely distributed and persists for a prolonged period at the tumor site owing to oral DHP23002 administration.

Efficacy and safety findings from DREAM: a phase III study of DHP107 (oral paclitaxel) versus i.v. paclitaxel in patients with advanced gastric cancer after failure of first-line chemotherapy

Background

Paclitaxel is currently only available as an intravenous (i.v.) formulation. DHP107 is a novel oral formulation of lipid ingredients and paclitaxel. DHP107 demonstrated comparable efficacy, safety, and pharmacokinetics to i.v. paclitaxel as a second-line therapy in patients with advanced gastric cancer (AGC). DREAM is a multicenter, open-label, prospective, randomized phase III study of patients with histologically/cytologically confirmed, unresectable/recurrent AGC after first-line therapy failure.

Methods and materials

Patients were randomized 1 : 1 to DHP107 (200 mg/m2 orally twice daily days 1, 8, 15 every 4 weeks) or i.v. paclitaxel (175 mg/m2 day 1 every 3 weeks). Patients were stratified by Eastern Cooperative Oncology Group performance status, disease status, and prior treatment; response was assessed (Response Evaluation Criteria in Solid Tumors) every 6 weeks. Primary end point: non-inferiority of progression-free survival (PFS); secondary end points: overall response rate (ORR), overall survival (OS), and safety. For the efficacy analysis, sequential tests for non-inferiority were carried out, first with a non-inferiority margin of 1.48, then with a margin of 1.25.

Results

Baseline characteristics were balanced in the 236 randomized patients (n = 118 per arm). Median PFS (per-protocol) was 3.0 (95% CI 1.7-4.0) months for DHP107 and 2.6 (95% CI 1.8-2.8) months for paclitaxel (hazard ratio [HR] = 0.85; 95% CI 0.64-1.13). A sensitivity analysis on PFS using independent central review showed similar results (HR = 0.93; 95% CI 0.70-1.24). Median OS (full analysis set) was 9.7 (95% CI 7.1 - 11.5) months for DHP107 versus 8.9 (95% CI 7.1-12.2) months for paclitaxel (HR = 1.04; 95% CI 0.76-1.41). ORR was 17.8% for DHP107 (CR 4.2%; PR 13.6%) versus 25.4% for paclitaxel (CR 3.4%; PR 22.0%). Nausea, vomiting, diarrhea, and mucositis were more common with DHP107; peripheral neuropathy was more common with paclitaxel. There were only few Grade≥3 adverse events, most commonly neutropenia (42% versus 53%); febrile neutropenia was reported infrequently (5.9% versus 2.5%). No hypersensitivity reactions occurred with DHP107 (paclitaxel 2.5%).

Conclusions

DHP107 as a second-line treatment of AGC was non-inferior to paclitaxel for PFS; other efficacy and safety parameters were comparable. DHP107 is the first oral paclitaxel with proven efficacy/safety for the treatment of AGC.

ClinicalTrials.gov

NCT01839773.

Antitumour effects of Liporaxel (oral paclitaxel) for canine melanoma in a mouse xenograft model

Paclitaxel, a member of the taxane family, exhibits antitumour effects by targeting the microtubules in cancer cells. Recently, oral paclitaxel has been developed to overcome the side effects of intravenous paclitaxel administration in human patients. The objective of this study was to investigate the antitumour effects of oral paclitaxel in vitro and in vivo. Three weeks after inoculation, oral paclitaxel (25 and 50 mg/kg) or saline was administered every week for three consecutive weeks. To explore the underlying mechanism, tumour angiogenesis was examined by immunohistochemistry with an anti-CD31 antibody. Tumour cell apoptosis was detected by Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling assay, and cell cycle arrest was confirmed by western blot analysis. Oral paclitaxel treatment of canine melanoma cells exerted mediated antiproliferative effects and mediated cell cycle arrest in vitro. In animal experiments, after oral paclitaxel administration, the average tumour size decreased to approximately 30% of that in the control. Histologically, oral paclitaxel showed anti-angiogenic effects and induced the apoptosis in tumour tissues. Oral paclitaxel also downregulated the intratumoural expression of cyclin D1 and inhibited cell proliferation. The study findings support potential application of oral paclitaxel as a novel chemotherapeutic strategy to treat canine melanoma. This is the first study to investigate the potential of oral paclitaxel as a therapeutic drug against canine tumours.

Nanopaclitaxel therapy: an evidence based review on the battle for next-generation formulation challenges

The poor solubility of paclitaxel (PTX), the most commonly used anticancer drug (Taxol^®), has long hindered the development of successful formulations. In 2005, the launch of Abraxane^®, a human albumin-based preparation of PTX, competed with Taxol^® in the commercial market. The success of Abraxane pushed other generic preparations aside, sparking competition among the global pharmaceutical companies to develop the novel and superior PTX nanotechnology-driven formulations. Unsurprisingly, the success underlying with cancer treatment using nano PTX therapy has now entered into a new era of drug development, patentability, preclinical and clinical evaluation, leading eventually to a significant increase in the regulatory approval of the products. The present article aims to provide recent progress in the development of nano PTX formulations by various pharmaceutical companies for safe and effective drug therapies for patients benefit.

An innovative in situ method of creating hybrid dendrimer nano-assembly: An efficient next generation dendritic platform for drug delivery

Dendrimers have proven to be effective for drug delivery and their biodisposition varies with change on their surface, generation and core. In an effort to understand the role of critical nanoscale design parameters, we developed a novel hybrid dendrimer approach to harness unique features of individual dendrimers and create a nano-assembly. We report an easy in situ method of creating hybrid dendrimer nano-assembly by mixing G4.0 PAMAM (-NH₂) and G3.5 PAMAM (-COONa) dendrimers with a chemotherapeutic drug docetaxel (DTX). Zeta potential, HR-TEM, ¹H-NMR proved the formation of nano-assembly. In vitro dissolution, release studies revealed pH dependent dissolution and sustained drug release. Cellular uptake, cytotoxicity, and flow cytometric analysis in human/mouse glioblastoma cells indicated the effectiveness of hybrid dendrimers. The oral administration of the hybrid dendrimers showed pharmacokinetic equivalence to intravenous injection of commercially available Taxotere®. Hybrid dendrimer concept provides much needed fine-tuning to create multistage next-generation dendritic platform in nanomedicine.

The battle of "nano" paclitaxel

Paclitaxel (PTX) is one of the three most widely used chemotherapeutic agents, together with doxorubicin and cisplatin, and is first or second line treatment for several types of cancers. In 2000, Taxol, the conventional formulation of PTX, became the best-selling cancer drug of all time with annual sales of 1.6 billion. In 2005, the introduction of the albumin-based formulation of PTX, known as Abraxane, ended Taxol's monopoly of the PTX market. Abraxane's ability to push the Taxol innovator and generic formulations aside attracted fierce competition amongst competitors worldwide to develop their own unique, new and improved formulation of PTX. At this time there are at least 18 companies focused on pre-clinical and/or clinical development of nano-formulations of PTX. These pharmaceutical companies are investing substantial capital to capture a share of the lucrative global PTX market. It is hoped that any formulation that dominates the market will result in tangible benefits to patients in terms of both survival and quality of life. Given all of this activity, here we address the question: Who is going to win the battle of "nano" paclitaxel?

A Phase I/IIa Study of DHP107, a Novel Oral Paclitaxel Formulation, in Patients with Advanced Solid Tumors or Gastric Cancer

Lessons Learned.

Ideally, patients should have access to an oral formulation of paclitaxel, as well as an intravenous formulation, to allow development of regimens exploring alternate schedules and to avoid reactions to Cremophor EL (BASF Corp., Ludwigshafen, Germany, https://www.basf.com).

DHP107 is a novel oral paclitaxel formulation that is a tolerable and feasible regimen for patients with gastric cancer, with data suggesting efficacy similar to that of intravenous paclitaxel.

Background.

We evaluated the maximum tolerated dose (MTD) of DHP107, a novel oral paclitaxel formulation, and the efficacy and safety of the agent in patients with advanced solid tumors.

Patients and Methods.

Phase I study: cohorts of 3–6 patients with advanced solid tumors received escalating DHP107 doses. Phase IIa study: patients with measurable advanced gastric cancer received DHP107, 200 mg/m² b.i.d., on days 1, 8, and 15 every 4 weeks. Pharmacokinetics, safety, and efficacy were analyzed.

Results.

Phase I: 17 patients received a dose‐escalating regimen of DHP107, 150–250 mg/m² b.i.d. Dose‐limiting toxicities were neutropenia and febrile neutropenia. The MTD (recommended dose) for phase IIa was 200 mg/m² b.i.d. Phase IIa: 11 patients with measurable advanced gastric cancer in whom first‐line therapy failed received DHP107 (MTD). Three confirmed partial responses were observed. Median progression‐free survival of gastric cancer patients (n = 16) treated at the MTD was 2.97 (95% confidence interval, 1.67–5.40) months (Fig. 1). The most frequent grade 3/4 adverse events were neutropenia (35.3%) and leukopenia (17.6%) at the MTD (phase I and IIa combined; n = 17).

Conclusion.

DHP107 showed good antitumor efficacy and was tolerable. The MTD (200 mg/m² b.i.d.) is recommended for use in further studies comparing DHP107 with standard intravenous paclitaxel therapy.

Absorption mechanism of DHP107, an oral paclitaxel formulation that forms a hydrated lipidic sponge phase

Paclitaxel is a most widely used anticancer drug with low oral bioavailability, thus it is currently administered via intravenous infusion. DHP107 is a lipid-based paclitaxel formulation that can be administered as an oral solution. In this study, we investigated the mechanism of paclitaxel absorption after oral administration of DHP107 in mice and rats by changing the dosing interval, and evaluated the influence of bile excretion. DHP107 was orally administered to mice at various dosing intervals (2, 4, 8, 12, 24 h) to examine how residual DHP107 affected paclitaxel absorption during subsequent administration. Studies with small-angle X-ray diffraction (SAXS) and cryo-transmission electron microscopy (cryo-TEM) showed that DHP107 formed a lipidic sponge phase after hydration. The AUC values after the second dose were smaller than those after the first dose, which was correlated to the induction of expression of P-gp and CYP in the livers and small intestines from 2 h to 7 d after the first dose. The smaller AUC value observed after the second dose was also attributed to the intestinal adhesion of residual formulation. The adhered DHP107 may have been removed by ingested food, thus resulting in a higher AUC. In ex vivo and in vivo mucoadhesion studies, the formulation adhered to the villi for up to 24 h, and the amount of DHP107 that adhered was approximately half that of monoolein. The paclitaxel absorption after administration of DHP107 was not affected by bile in the cholecystectomy mice. The dosing interval and food intake affect the oral absorption of paclitaxel from DHP107, which forms a mucoadhesive sponge phase after hydration. Bile excretion does not affect the absorption of paclitaxel from DHP107 in vivo.

Cubosomes: remarkable drug delivery potential

Cubosomes are nanostructured liquid crystalline particles, made of certain amphiphilic lipids in definite proportions, known as biocompatible carriers in drug delivery. Cubosomes comprise curved bicontinuous lipid bilayers that are organized in three dimensions as honeycombed structures and divided into two internal aqueous channels that can be exploited by various bioactive ingredients, such as chemical drugs, peptides and proteins. Owing to unique properties such as thermodynamic stability, bioadhesion, the ability of encapsulating hydrophilic, hydrophobic and amphiphilic substances, and the potential for controlled release through functionalization, cubosomes are regarded as promising vehicles for different routes of administration. Based on the most recent reports, this review introduces cubosomes focusing on their structure, preparation methods, mechanism of release and potential routes of administration.

Metronomic oral paclitaxel shows anti-tumor effects in an orthotopic mouse model of ovarian cancer

Objective

The purpose of this study was to compare the in vivo anti-tumor efficacy of a mucoadhesive, lipid-based, oral paclitaxel formulation (DHP107) with traditional, intraperitoneal (IP) paclitaxel using an orthotopic mouse model of chemotherapy-sensitive SKOV3ip1 ovarian cancer.

Methods

To determine the optimal therapeutic dose of oral paclitaxel, DHP107 was administered per os to female athymic nude mice at 0, 25, or 50 mg/kg twice per week. Control mice received 100 µL saline once per week. IP injections of paclitaxel at 5 mg/kg once per week were used for comparison. To evaluate the potential therapeutic effect of metronomic DHP107 chemotherapy, mice received DHP107 50 mg/kg once per week per os, which was compared with 25 mg/kg twice per week and with vehicle-treated controls.

Results

Low-dose DHP107 (25 mg/kg) twice per week was as effective as IP paclitaxel (5 mg/kg once a week) but high-dose DHP107 (50 mg/kg once per week) was less effective at inhibiting tumor growth in an orthotopic mouse model (88%, 82%, and 36% decrease in tumor weight, respectively). Mice that received 25 mg/kg DHP107 twice per week or 50 mg/kg DHP107 once per week per os had a significant decrease in tumor weight compared with vehicle-treated controls (p<0.01, both doses).

Conclusion

Metronomic oral chemotherapy with DHP107 showed anti-tumor efficacy in vivo similar to IP paclitaxel in an orthotopic mouse model.

Carboxymethyl-chitosan-tethered lipid vesicles: hybrid nanoblanket for oral delivery of paclitaxel

We describe the development and evaluation of a hybrid lipopolymeric system comprising carboxymethyl chitosan (CMC), covalently tethered to phosphatidylethanolamine units on the surface of lipid nanovesicles, for oral delivery of paclitaxel. The bioploymer is intended to act as a blanket, thereby shielding the drug from harsh gastrointestinal conditions, whereas the lipid nanovesicle ensures high encapsulation efficiency of paclitaxel and its passive targeting to tumor. CMC-tethered nanovesicles (LN-C-PTX) in the size range of 200-300 nm improved the gastrointestinal resistance and mucoadhesion properties as compared with unmodified lipid nanovesicles (LN-PTX). Conjugation of CMC did not compromise the cytotoxic potential of paclitaxel yet facilitated the interaction and uptake of the nanovesicles by murine melanoma (B16F10) cells through an ATP-dependent process. CMC-conjugated nanovesicles, upon oral administration in rats, improved the plasma concentration profile of paclitaxel, with 1.5 fold increase in its bioavailability and 5.5 folds increase in elimination half life in comparison with Taxol. We also found that CMC in addition to providing a gastric resistant coating also imparted stealth character to the nanovesicles, thereby reducing their reticuloendothelial system (RES)-mediated uptake by liver and spleen and bypassing the need for PEGylation. In vivo efficacy in subcutaneous model of B16F10 showed significantly improved tumor growth inhibition and survival with CMC-tethered nanovesicles as compared with unmodified nanovesicles, both administered orally. LN-C-PTX exhibited therapeutic efficacy comparable to Taxol and Abraxane and also showed reduced toxicity and improved survival. Overall, these results suggest the therapeutic potential of CMC tethered nanovesicles as a platform for oral administration of paclitaxel and also unravel the ability of CMC to impart stealth character to the nanoparticles, thereby preventing their RES clearance.

Novel oral taxane therapies: recent Phase I results

The oral taxanes are analogues of existing taxanes with a possible broad range of antitumor activity. They also have the potential advantages of ease of administration, better efficacy and lesser toxicity than currently available taxanes. These drugs have been used in several Phase I clinical trials, the methodology and results of which will be reviewed here.

Radiation-guided drug delivery to mouse models of lung cancer

PURPOSE

The purpose of this study was to achieve improved cancer-specific delivery and bioavailability of radiation-sensitizing chemotherapy using radiation-guided drug delivery.

EXPERIMENTAL DESIGN

Phage display technology was used to isolate a recombinant peptide (HVGGSSV) that binds to a radiation-inducible receptor in irradiated tumors. This peptide was used to target nab-paclitaxel to irradiated tumors, achieving tumor-specificity and enhanced bioavailability of paclitaxel.

RESULTS

Optical imaging studies showed that HVGGSSV-guided nab-paclitaxel selectively targeted irradiated tumors and showed 1.48 ± 1.66 photons/s/cm(2)/sr greater radiance compared with SGVSGHV-nab-paclitaxel, and 1.49 ± 1.36 photons/s/cm(2)/sr greater than nab-paclitaxel alone (P < 0.05). Biodistribution studies showed >5-fold increase in paclitaxel levels within irradiated tumors in HVGGSSV-nab-paclitaxel-treated groups as compared with either nab-paclitaxel or SGVSGHV-nab-paclitaxel at 72 hours. Both Lewis lung carcinoma and H460 lung carcinoma murine models showed significant tumor growth delay for HVGGSSV-nab-paclitaxel as compared with nab-paclitaxel, SGVSGHV-nab-paclitaxel,and saline controls. HVGGSSV-nab-paclitaxel treatment induced a significantly greater loss in vasculature in irradiated tumors compared with unirradiated tumors, nab-paclitaxel, SGVSGHV-nab-paclitaxel, and untreated controls.

CONCLUSIONS

HVGGSSV-nab-paclitaxel was found to bind specifically to the tax-interacting protein-1 (TIP-1) receptor expressed in irradiated tumors, enhance bioavailability of paclitaxel, and significantly increase tumor growth delay as compared with controls in mouse models of lung cancer. Here we show that targeting nab-paclitaxel to radiation-inducible TIP-1 results in increased tumor-specific drug delivery and enhanced biological efficacy in the treatment of cancer.