1084 - Oral paclitaxel in the treatment of metastatic breast cancer (MBC) patients Dai MS1, Chao TY2, Chao TC3, Chiu CF4, Lu YS5, Shiah HS6, YY Wu1, WH Cheng2, 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 Multicenter, single-arm, open-label, PK study of Oraxol Intravenous (IV) paclitaxel is an effective treatment (HM30181A at 15mg, plus oral paclitaxel 205mg/m2) for breast cancer. Oral administration paclitaxel is administered orally for 3 consecutive days weekly for up to preferable to IV regarding minimizing IV injections, 16 weeks. Paclitaxel PK was assessed at week-1 and week- anaphylactic reactions to cremaphor, steroid pre- 4. Tumor Response was measured at weeks 8 and 16 using medications, hospital visits, and relevant costs. RECIST criteria 1.1. Toxicity was assessed using CTCAE However, paclitaxel has poor oral absorption due v4.03. to active excretion by P-glycoprotein (Pgp) in the RESULTS intestinal cells. Oraxol (Athenex, USA) is an oral Twenty-eight MBC patient were studied with a mean age of paclitaxel and HM30181, a novel oral inhibitor of 56.6 years (range: 38 - 79 yrs). 26 patients had failed intestinal P-gp which enables the oral mutiple previous chemotherapies. There were 11 (42.3%) administration of paclitaxel. We report the final partial response, 12 (46.2%) stable disease and 3 (11.5%) results of a pharmacokinetics (PK) study, including progressive disease in 26 evaluable patients. Three clinical response and tolerability of Oraxol in patients had treatment-related SAEs (grade ≥3 neutropenia) treatment of metastatic breast cancer patients. and all patients recovered completely. PK results showed that the AUC of oral paclitaxel at week-1 was reproducible CONCLUSION at week-4 (3050 to 3594 ng-hr/mL). HM30181: MOA 1. Weekly oral paclitaxel can achieve paclitaxel exposure similar to that of weekly IV paclitaxel (80mg/m2) reported previously. PK of oral paclitaxel is reproducible. 2. Oraxol appears effective in the treatment of advanced breast cancer patients. The tumor response rate (PR= 42.3%, SD= 46.2%) of Oraxol in treatment of metastatic breast cancer patients who failed previous chemotherapies is very encouraging. 3. The drug toxicity profile of Oraxol appears tolerable ClinicalTrials.gov Identifier: NCT03165955.