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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 [ 3 H]DHP107 and [ 18 F]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 [ 18 F]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 [ 18 F]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 [ 3 H]- and [ 18 F]DHP107 in healthy mice. The [ 18 F]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 [ 18 F]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., (© 2021 The Authors. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of the American Society for Clinical Pharmacology and Therapeutics.)

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., (© 2019 John Wiley & Sons Ltd.)

An oral paclitaxel formulation that overcomes the hypersensitivity reaction of paclitaxel has been evaluated for safety and efficacy in humans, but not in dogs. We present the first case report on the use of oral paclitaxel in dogs. In this study, oral paclitaxel was well-tolerated in four dogs with either transitional cell carcinoma or prostate cancer; adverse effects were limited to mild neutropenia. Each of the dogs had progressive disease at the end, but clinical responses, including changes in mass size and improvement of clinical symptoms, were confirmed in some of the animals following oral paclitaxel chemotherapy. Although this study is somewhat limited by a small sample size, it suggests that oral paclitaxel may be a chemotherapeutic option for malignant tumors in dogs.

DHP107, an oral formulation of paclitaxel, is effectively and systemically absorbed in intestinal endothelial cells. Although the in vivo efficacy of DHP107 has been reported, the potential toxicity of DHP107 has not been evaluated. Therefore, this study was conducted to evaluate the toxicity and toxicokinetics of DHP107 orally administered to ICR mice at 25, 50, and 100 mg/kg via once-weekly dosing for six weeks. DHP107-related clinical signs were observed in both sexes at 100 mg/kg. There were significant increases in the number of platelets and percentages of reticulocytes and basophils in male mice. Also in males, there was a significant decrease in the absolute and relative weights of testes, epididymides, kidneys, and heart. Relative spleen weights were significantly increased in males treated with doses ≥50 mg/kg which had histopathological correlates. These changes were reversible after a two-week recovery period with the exception of the findings in the reproductive organs. Systemic exposure to paclitaxel increased with DHP107 doses in single and multiple dosing with no marked differences between sexes. In conclusion, the target organs were determined to be the reproductive and hematopoietic organs in male mice, suggesting of sex difference and the NOAEL of DHP107 was established to be < 25 mg/kg for males and 50 mg/kg for females., (Copyright © 2019 Elsevier Inc. All rights reserved.)

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. [ABSTRACT FROM AUTHOR]