逆説的なMAPK経路の活性化を回避するRAF阻害剤
Chao Zhang1, Wayne Spevak1, Ying Zhang1
1Plexxikon Inc., 91 Bolivar Drive, Berkeley, California 94710, USA.
Nature
|October 16, 2015
まとめ
次世代のRAF阻害剤,または"パラドックスブレーカー"は,パラドックス経路の活性化なしに,BRAF変異によって引き起こされる癌の成長を効果的に抑制します. これらの新薬は,第一世代のRAF阻害剤と比較して,有効性が向上し,耐性を克服しています.
科学分野:
- 腫瘍学
- 分子生物学
- 薬理学について
背景:
- 腫瘍性BRAF変異はMAPK経路を通じて癌を誘導し,メラノーマに対するRAF阻害剤のような標的型療法につながる.
- 最初の世代のRAF阻害剤は,逆説的にMAPK経路を活性化し,特定の癌,特にRASまたは受容体チロシンキナーゼの活性化がある癌の成長を刺激します.
- この逆説的な活性化は 癌治療における重要な課題であり,有効性と耐久性を制限します.
研究 の 目的:
- 逆説的なMAPK経路の活性化なしに突然変異したBRAFを選択的に抑制する"パラドックスブレーカー"と呼ばれる次世代RAF阻害剤を特定し,特徴づけること.
- 最初の世代のRAF阻害剤に耐性を持つがんを含むがんの臨床前モデルにおけるこれらのパラドックスブレーカーの有効性を評価する.
- 抗レジスタンスメカニズムを克服し,RAF阻害剤療法の安全性と耐久性を改善するパラドックスブレーカーの可能性を評価する.
主な方法:
- 新しいATP競争性のRAF阻害剤の開発とスクリーニング
- 癌細胞系とBRAFまたは上流変異を有する異種移植モデルにおけるRAF阻害剤のインビトロおよびインビボ試験.
- MAPK経路のシグナル伝達,細胞増殖,RAF阻害剤に対する遺伝子発現の分析.
- 第"世代のRAF阻害剤に対する耐性メカニズムの評価と,パラドックスブレーカーの効果の評価.
主要な成果:
- 次世代のRAF阻害剤 (PLX7904,PLX8394) は,逆説的なMAPK経路活性化なしに変異したBRAFがん細胞を抑制しました.
- ベムラフェニブとは異なり,パラドックスブレーカーは,HRAS変異を有する細胞におけるMAPK経路応答遺伝子を刺激したり誘導したりしませんでした.
- パラドックスブレーカーは,第1世代のRAF阻害剤に対する既知の耐性メカニズムを克服する効果を示した.
結論:
- 次世代のRAF阻害剤 ("パラドックスブレーカー") は,MAPK経路阻害とパラドックス活性化を分離することで,有望な治療戦略を提供します.
- これらの薬剤は,第一世代のRAF阻害剤と比較して,安全性が向上し,有効性が持続する可能性があります.
- PLX8394の臨床評価は進行中であり,RAF阻害剤療法におけるパラダイムシフトの可能性を示唆しています.
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