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ニュースリリース

(2005年12月12日) 印刷用(PDF 36.0KB)


新規乳がん治療剤E7389の
フェーズⅡ試験データの米国での学会発表について

 エーザイ株式会社(本社:東京都、社長:内藤晴夫)の米国臨床研究子会社エーザイ・メディカル・リサーチ・インク(本社:ニュージャージー州、社長:ミンデル・サイドリン)は、米国サンアントニオ市(テキサス州)で開催された乳がんシンボジウム(San Antonio Breast Cancer Symposium)において、E7389の進行した他剤無効例の乳がんに対する安全性および有効性データの最新解析結果を発表しました。E7389は、極めて強力な抗腫瘍活性を持つことが前臨床試験で示されており、クロイソカイメン由来の海洋天然物ハリコンドリンBに類似した合成化合物です。
 今回発表した臨床試験の目的は、他剤無効の乳がん患者における単剤療法としてE7389を評価することです。本臨床試験の主要エンドポイントは、RECIST(Response Evaluation Criteria In Solid Tumors:固形がんに対する効果を判定する際に用いられる評価基準)に基づいて評価された奏効率です。

 71人の女性患者が28日間を1サイクル(投与期間の単位)とした試験に登録され、そのうち65人の患者での最新の有効性データと、48人の患者での安全性データが得られました。
 腫瘍縮小効果の判定が可能とされた65人の患者は、最低でも2サイクルを完了して腫瘍評価を行い、投与前との比較で腫瘍縮小効果が判定されました。
 評価可能患者65人のうち、4サイクルを終了した段階で10例のPR (Partial Response、部分奏効、50%以上の腫瘍縮小効果)が確認され、21例はSD (Stable Disease、安定)を示しました。進行した他剤無効の乳がん患者における15%の奏効率は、新規抗がん剤としての可能性が期待できます。

 今回の試験結果によると、E7389に関連した主要な副作用は好中球減少症でした。その他の副作用は軽度から中等度の吐き気、疲労感、脱水症、関節痛、呼吸困難、および神経障害などでした。なお、血液毒性が原因で試験を中断した症例はありませんでした。

 今回発表した試験は継続中であり、試験終了後に最終的な結果を得ることになります。なお、E7389については、現在、サブパートH申請を目指した後期フェーズⅡ臨床試験が進行しています。



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●エーザイ・インクによるリリース文


Eisai Announces Phase II Data on E7389, a Potential New Therapy for the Treatment of Breast Cancer

Marine Sponge Molecule is Model for Novel Anti-Tubulin Agent


SAN ANTONIO, DECEMBER 8, 2005-Researchers today presented preliminary safety and efficacy data for E7389 in the treatment of advanced, refractory breast cancer during the San Antonio Breast Cancer Symposium. E7389 is a synthetic analog of halichondrin B (HB), which is a natural product shown in preclinical studies to have highly potent anti-cancer activity in vitro and in vivo. Halichondrin B was originally isolated from a type of marine sponge.

This study was designed to evaluate E7389 as a monotherapy in patients with refractory breast cancer. The primary endpoint of this trial was response rate, measured using the RECIST (Response Evaluation Criteria In Solid Tumors) criteria - a group of standards used to measure responses to treatment in solid tumors.

Of the 65 evaluable patients, 10 partial responses were confirmed at the 4th cycle assessment. Twenty-one patients had stable disease (SD). In treatment-refractory patients with advanced breast cancer this preliminary response rate (15%) appears promising.

Based on the preliminary results of this study, the predominant serious side effect related to E7389 was neutropenia (low white blood cell counts). Other side effects were considered mild to moderate and included nausea, fatigue, dehydration, arthralgias, dyspnea and neuropathy. None of the patients discontinued the study due to hematological toxicity.

"The results from this study with E7389 appear promising, and clinical research on E7389 as a treatment for breast cancer is continuing," said Sandra Silberman, MD, PhD, Associate Vice President and Global Therapeutic Area Head, Oncology at Eisai Medical Research, Inc. "E7389 is an example of Eisai's human health care (hhc) commitment to satisfy unmet medical needs of patients and their families. Eisai has targeted oncology/critical care as one of three key therapeutic areas of focus," she added.

Seventy-one women were enrolled in the 28-day cycle patient group. Preliminary efficacy data for 65 patients and safety data on 48 patients are available. The 65 patients considered evaluable for response had completed at least their 2nd cycle of treatment and had a tumor assessment, which could be compared to their baseline. This study is ongoing, and final results may change from the initial analysis.

"My colleagues and I are very excited by the results of this study so far," said Linda T. Vahdat, MD, Associate Professor of Clinical Medicine and Medical Director, Breast Cancer Program at Cornell University New York Presbyterian Hospital. "We look forward to additional studies with this novel compound."

Pre-clinical studies demonstrate that E7389 suppresses the growth of cellular microtubules, which are essential for cell division. By doing so, E7389 appears to stop the production of new cancer cells and ultimately results in the programmed death of the existing cancer cells, a process known as apoptosis.



Breast Cancer
In spite of recent developments in the treatment of advanced breast cancer, it remains incurable. It is a major health care problem due to its high incidence: approximately 212,000 new cases of invasive breast cancer will be diagnosed in 2005 in the US, and in 2005 an estimated 40,870 people will die from breast cancer. Although mammographic screening advances the time of diagnose, 20-89% of those diagnosed at an early phase, depending on stage and treatment, develop metastases within five years. Developing new and well-tolerated drugs for the control of advanced, relapsed or refractory breast cancer is a justified endeavor and a continuous challenge to the pharmaceutical industry.

E7389: A Cooperative Research and Development Program
E7389 was developed through a cooperative program between the National Cancer Institute (NCI) and Eisai Research Institute (ERI) in Andover, Massachusetts. In 1992, ERI scientists determined that the anticancer activity of HB resides in one half of the molecule. E7389 was finally isolated following the synthesis of more than 200 analogues of this anticancer half. ERI and the NCI entered into a cooperative research and development agreement (CRADA) in 2001 and the first Phase I study of E7389 was initiated in 2002. Eisai initiated two Phase I studies of E7389 in 2003, and Phase II studies began in 2004.

About Eisai Medical Research Inc.
Eisai Medical Research Inc. is a U.S. pharmaceutical subsidiary of Eisai Co., Ltd. Eisai Co., Ltd. is a research - based human health care company that discovers, develops and markets products in more than 30 countries. Eisai Medical Research Inc. was established to focus solely on clinical research and to expedite clinical drug development of new chemical entities and of new indications for marketed products.