287PD- An open-label, single-arm pharmacokinetic study of oral paclitaxel and HM30181 in metastatic breast cancer patients Dai MS1, Chao TY2, Chao TC3, Chiu CF4, Lu YS5, Shiah HS6, Hung N7, Fetterly G7, Cutler DL7, Kwan R7, Kramer D7, Chan W7, Hung T8 1Division of Hematology/Oncology, Tri-Service General Hospital, Taipei, Taiwan., 2Division of Hematology-Oncology, Taipei Medical University- Shuang Ho Hospital, New Taipei City, Taiwan . 3Division of Medical Oncology, Taipei Veterans General Hospital, Beitou District, Taipei, Taiwan, 4Department of Medical Oncology, China Medical University Hospital, Taichung, Taiwan, 5Department of Medical Oncology, National Taiwan University Hospital, Taipei, Taiwan, 4Department of Medical Oncology, China Medical University Hospital, Taichung, Taiwan, 5Department of Medical Oncology, National Taiwan University Hospital, Taipei, Taiwan 7University of Otago, Dunedin, New Zealand 7Athenex, Buffalo, NY, 8Zenith Technology Corporation Limited, Dunedin, New Zealand. INTRODUCTION MATERIALS AND METHODS We conducted a multicenter, single-arm, open-label study Intravenous (IV) paclitaxel is an approved treatment recruiting breast cancer patients from 6 medical centers in for breast cancer. Oral administration of Taiwan. HM30181 15mg plus oral paclitaxel 205mg/m2 (Oraxol) chemotherapy is preferable to IV form with regard were administered orally daily for 3 consecutive days and to minimized IV access, reduced allergic reactions weekly for up to 16 weeks. PK blood samples were collected in to cremaphor, steroid pre-medication, hospital stay, the first and fourth week of Oraxol treatment at the designated and relevant cost. However, paclitaxel has poor timepoints. oral bioavailability due to active excretion by p- RESULTS glycoprotein (Pgp) on intestinal epithelial cells. Oraxol (Athenex, USA) is a combination of oral Twenty-four patients were recruited into this study with paclitaxel and HM30181, a novel oral non-absorbed evaluable tumor response. Eleven patients (45.8%) achieved partial responses and 10 patients (41.7%) had stable disease. specific inhibitor of intestinal Pgp. We report the Twenty-one patients remained progression-free after median pharmacokinetic (PK) results and clinical response 16-week follow-up (CBR= 95.8%). There were 7 drug-related of Oraxol in metastatic breast cancer patients. severe adverse events (grade ≥3 neutropenia) occurred in 3 patients. PK samples from 24 subjects demonstrated similar HM30181: MOA plasma concentrations (AUC) to IV paclitaxel. CONCLUSION 1. Plasma paclitaxel exposure (AUC) of oral paclitaxel achieved is similar to that reported for weekly IV Paclitaxel 2. The tumor response rate (PR= 45.8%, SD= 41.7%) of Oraxol in treatment of breast cancer patients who failed previous chemotherapies is very encouraging 3. The drug toxicity profile of Oraxol appears tolerable 4. Oraxol appears effective and safe in the treatment of advanced breast cancer patients ClinicalTrials.gov Identifier: NCT03165955.