Abstract P3-10-04: A open-label, randomized, parallel, phase III trial to evaluate the efficacy and safety of Genexol®-PM compared to Genexol®(conventional paclitaxel with cremorphor EL) in recurrent or metastatic breast cancer patients
Authors: Ro Jung Sil , Sohn Joo Hyuk , Kim Sung Bae , Lee Keun Seok , Chung Joo Seop , Park Jae Hoo , Lee Soo Hyeon , Kim Tae You , Jung Kyung Hae , Cho Eun Kyung , Kim Yang Soo , Song Hong Suk , Seo Jae Hong , Ryoo Hun Mo , Lee Sun Ah , Yoon So Young , Kim Chul Soo , Kim Yong Tai , Sung Hwa Jung , Kim Si Young , Lee Yong Jin 
Published: May 2015

Background: The rationale for developing an alternative paclitaxel formulation concerns Cremophor EL-related side effects, and a novel paclitaxel delivery system might augment its therapeutic efficacy. Genexol-PM is a novel polymeric micelle formulated paclitaxel free of Cremophor. The polymeric micelle formulation is composed of hundreds of low molecular weight, non-toxic, and biodegradable amphiphilic diblock copolymers which include monomethoxy poly (ethylene glycol)-block-poly (D,L-lactide). This multicenter phase III study was designed to evaluate the non-inferiority of efficacy of Genexol-PM compared to conventional CrEL-based paclitaxel.

Methods: In this phase III study, 213 patients were enrolled onto the study and randomly assigned (1:1) to treatment group according to prior recurrent or metastatic breast cancer chemotherapy. The study evaluated the objective response rate for the primary objective, and others including overall survival (OS), progression free survival (PFS), time to tumor progression (TTP), duration of overall response and adverse events. Eligible patients were randomly assigned to receive either Genexol-PM or standard paclitaxel. Genexol-PM or standard paclitaxel was administered on the first day of every 3 weeks. Measurable disease was assessed by imaging using the RECIST 1.0 criteria.

Results: The objective response rate (ORR) was higher by the administration of the study drug (39.05% v 24.30% in ITT, 56.92% v 39.29% in PP). One-sided 95% upper confidence limit was -4.36%, which is lower than the non-inferiority threshold (7%), indicating that the study group is not inferior to the control group. OS, PFS, TTP and duration of overall response were analyzed in the ITT population. The analysis of OS showed no significant difference (p=0.5878) (859 days, 95% CI : 732.00∼1,025.00 v 726 days, 95% CI : 553.00∼ -). Median PFS periods were 232 days (95% CI: 164.00∼274.00) vs. 191 days (95% CI: 159.00∼237.00). Median TTPs were 233 days (95% CI: 165.00∼286.00) vs. 191 days (95% CI: 159.00∼241.00) between the groups. Difference in PFSs and TTPs between the groups were not statistically significant. (p=0.2407, 0.2076, respectively) Genexol-PM was not significantly different from the comparator in terms of safety.

Conclusion: Genexol-PM demonstrated non-inferior efficacy and comparable safety profile compared with standard paclitaxel in this patient population. Of note, Genexol-PM permits the delivery of a higher paclitaxel dose without additional toxicity achieved with CrEL-based formulation. In the absence of CrEL, no filter or special tubing is required that conventional PVC infusion sets can be used.

Citation Format: Jung Sil Ro, Joo Hyuk Sohn, Sung Bae Kim, Keun Seok Lee, Joo Seop Chung, Jae Hoo Park, Soo Hyeon Lee, Tae You Kim, Kyung Hae Jung, Eun Kyung Cho, Yang Soo Kim, Hong Suk Song, Jae Hong Seo, Hun Mo Ryoo, Sun Ah Lee, So Young Yoon, Chul Soo Kim, Yong Tai Kim, Hwa Jung Sung, Si Young Kim, Yong Jin Lee. A open-label, randomized, parallel, phase III trial to evaluate the efficacy and safety of Genexol®-PM compared to Genexol®(conventional paclitaxel with cremorphor EL) in recurrent or metastatic breast cancer patients [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-10-04.