Osimertinib

Osimertinib (オシメルチニブ)

一行要約

3rd-gen mutant-selective EGFR-TKI。EGFR exon 19 deletion / L858R activating mutation と T790M gatekeeper mutation の双方に高活性を持ち、wild-type EGFR への親和性が低いため皮膚・消化器毒性が大幅に軽減された “covalent C797 binder”。1L (FLAURA, PFS HR 0.46 → OS HR 0.80)、adjuvant (ADAURA, DFS HR 0.20)、Stage III consolidation (LAURA, PFS HR 0.16)、2L T790M+ (AURA3, PFS HR 0.30) と stage 横断の四冠を達成し、EGFR+ NSCLC 全 stage の backbone。BBB 透過性に優れ脳・髄膜転移にも高活性を示す。耐性機序は C797S / MET amplification / lineage plasticity (SCLC・squamous transformation) が三大要因で、耐性後 sequential strategy (Amivantamab + Lazertinib、chemo + bevacizumab、ADC) が現在の最大課題。

主要エビデンス

1L Advanced (FLAURA / FLAURA2)

FLAURA は untreated EGFR exon 19del / L858R NSCLC 556 例で osimertinib vs SoC EGFR-TKI (gefitinib / erlotinib) を比較し、PFS 18.9 vs 10.2 ヶ月 (HR 0.46) の primary 達成 (Soria et al. NEnglJMed 2018)、OS でも 38.6 vs 31.8 ヶ月 (HR 0.80) の有意改善 (Ramalingam et al. NEnglJMed 2020) を示し、現代 1L EGFR-TKI の global standard を確立した。日本人 subset でも consistency が確認されている (Ohe et al. JpnJClinOncol 2019、Ramalingam et al. JClinOncol 2018)。さらなる強化として FLAURA2 (osimertinib + carboplatin/pemetrexed vs osimertinib 単剤) が PFS 25.5 vs 16.7 ヶ月 (HR 0.62) を示し、特に高リスク (CNS metastases / TP53 co-mutation) で大きな benefit を呈した。

2L T790M+ (AURA / AURA3)

T790M+ 2L 領域では AURA3 が osimertinib vs platinum + pemetrexed の比較で PFS 10.1 vs 4.4 ヶ月 (HR 0.30)、ORR 71% vs 31% の圧倒的優位を示し (Mok et al. NEnglJMed 2017)、T790M+ 2L の standard を確立。前段階の AURA phase I/II (Janne et al. NEnglJMed 2015) で T790M+ ORR 61% を示した時点で 3rd-gen mutant-selective concept が確立されていた。1L osimertinib 普及で T790M+ 2L 適応自体は縮小したが、leptomeningeal disease 領域では Park et al. AnnOncol 2020 (高用量 160 mg)、Yang et al. JClinOncol 2020 (BLOOM)、Ahn et al. JThoracOncol 2020 が標準を成す。

Adjuvant (ADAURA)

Stage IB–IIIA 切除後 EGFR-mut NSCLC 682 例で osimertinib 3 年投与 vs placebo を比較した ADAURA が DFS HR 0.20 (Stage II–IIIA、24 ヶ月 DFS 90% vs 44%)、5-yr OS HR 0.49 を示し (Wu et al. NEnglJMed 2020、Wu et al. NEnglJMed 2020)、adjuvant EGFR-TKI 領域でこれまで陰性であった RADIANT / CTONG1104 (gefitinib) を凌駕する歴史的結果となった。

Stage III consolidation (LAURA)

切除不能 Stage III EGFR-mut NSCLC で CRT 後 osimertinib consolidation vs placebo (LAURA、Lu 2024 NEJM) が PFS 39.1 vs 5.6 ヶ月 (HR 0.16) を示し、Durvalumab PACIFIC の “EGFR-mut 版” となった。EGFR-mut で IO 効果が乏しい現実 (Aredo et al. JThoracOncol 2021) を踏まえた臨床的意義は大きい。

CNS efficacy

Osimertinib は des-methyl 代謝物 AZ5104 が BBB を透過し、preclinical model で 1st/2nd-gen TKI を上回る脳組織内濃度を示し (Ballard et al. ClinCancerRes 2016)、CNS metastases を伴う FLAURA / AURA3 subgroup でも CNS PFS / ORR 改善を示した (Reungwetwattana et al. JClinOncol 2018、Wu et al. JClinOncol 2018、Magnuson et al. JClinOncol 2017)。これにより EGFR-mut NSCLC の brain mets management で WBRT を遅らせる戦略が確立された。

耐性機序

1L osimertinib 後の耐性 landscape は MET amplification (約15%) 、C797S (約7%、cis/trans 配置で治療戦略が異なる) 、HER2 amp、PIK3CA、RAS 系活性化、histological transformation (SCLC / squamous) が主要 ((Ramalingam et al. ESMO 2018)、Piotrowska et al. CancerDiscov 2018、Schoenfeld et al. ClinCancerRes 2020)。C797S は Thress et al. NatMed 2015 が初記載、SCLC transformation には RB1/TP53 biallelic loss が背景にある (Niederst et al. NatCommun 2015)。MET amp + osimertinib に対する savolitinib 併用の TATTON / SAVANNAH (Sequist et al. LancetOncol 2020)、osimertinib + bevacizumab (Akamatsu et al. JAMAOncol 2021) が代表的 sequential strategy。Original AZD9291 mechanism 自体は Cross et al. CancerDiscov 2014 が確立。

メカニズム

• Osimertinib は EGFR kinase domain の C797 cysteine に共有結合する mono-anilino-pyrimidine 骨格 3rd-gen mutant-selective TKI
• Wild-type EGFR への親和性は gefitinib の約 1/200 で、皮疹・下痢が軽減し long-term tolerability が向上
• T790M (2nd-gen 耐性 gatekeeper) に高活性を保持し、L858R / exon 19 del への activity も維持
• 活性代謝物 AZ5104 / AZ7550 が同等以上の kinase 活性を持ち、AZ5104 は高い BBB 透過性を介し CNS で薬効を発揮
• 耐性: ① C797S (covalent binding site mutation) → T790M との cis 配置では 1st-gen TKI 単剤で resensitize 困難、trans 配置なら 1st + 3rd-gen combo が一部有効 (Wang et al. JThoracOncol 2017) ② MET amp → Amivantamab / MET-TKI 併用 ③ HER2 amp → ADC 候補 ④ lineage plasticity (SCLC / squamous transformation) → EP 化療等への switch

臨床位置づけ

• 1L EGFR-mut NSCLC: FLAURA に基づき exon 19 del / L858R で global standard。FLAURA2 を踏まえ、TP53 co-mut / CNS mets / L858R 等の高リスク患者では osimertinib + chemo を選択肢化
• Adjuvant (Stage IB–IIIA) : ADAURA に基づき術後補助療法の standard (3 年投与)。OS benefit 確認済み
• Stage III consolidation: LAURA に基づき CRT 後 consolidation (EGFR-mut 版 Durvalumab)
• 2L T790M+: AURA3。1L osimertinib 普及で適用機会は減少。Pretreated CNS / leptomeningeal では 160 mg osimertinib も選択肢
• Post-Osimertinib: Amivantamab + Lazertinib (MARIPOSA-2)、carboplatin/pemetrexed + bevacizumab、HER3-DXd / Dato-DXd 等の ADC が候補

Open Questions

• 1L combination の患者選択: FLAURA2 (chemo 上乗せ) vs MARIPOSA (amivantamab + lazertinib) vs osimertinib 単剤 — TP53 / EGFR allele / CNS で個別化
• C797S sequencing: 4th-gen allosteric inhibitor (patritumab-DXd 後の TKI) の臨床開発
• MRD-guided adjuvant: ADAURA 3 年固定 vs ctDNA-driven duration 個別化
• 耐性後 ADC: HER3-DXd (patritumab-DXd) / Dato-DXd / Ivonescimab 等の sequencing
• EGFR-mut + IO: 効果限定的 (Aredo et al. JThoracOncol 2021) であるが、CRT 後 atezolizumab / bevacizumab 併用などの探索

重要論文 Top 10

1. ★★★★★ Ramalingam et al. NEnglJMed 2020 — FLAURA OS — 1L OS benefit 確立
2. ★★★★★ Wu et al. NEnglJMed 2020 — ADAURA — Adjuvant DFS HR 0.20 歴史的
3. ★★★★★ Soria et al. NEnglJMed 2018 — FLAURA primary — 1L PFS HR 0.46
4. ★★★★ Mok et al. NEnglJMed 2017 — AURA3 — T790M+ 2L 標準化
5. ★★★★ Cross et al. CancerDiscov 2014 — AZD9291 mechanism — 3rd-gen concept 確立

関連エンティティ

• Drug class: EGFR-TKI
• 標的遺伝子: EGFR
• 併用相手: Amivantamab (MARIPOSA-2), Platinum-chemotherapy (FLAURA2)
• 耐性関連: MET-TKI, C797S
• 試験: FLAURA, ADAURA, AURA3
• Concept: EGFR-TKI-resistance, Lineage-plasticity
• ドメイン: lung-cancer-treatment

関連論文

直近 30 件のみ表示中 (関連 327 件)。 全件は MOC ページ または Obsidian (source Markdown) から辿れます。

Basic-Brain metastasis

• Mavrikios et al. AnnOncol 2026 — Lung cancer brain metastases management at the dawn of personalized medicine are we ready to break the barriers
• Chen et al. FrontOncol 2026 — Stereotactic radiotherapy for brain metastases indications, dose fractionation, technological innovations, and evolving
• Jiang et al. FrontOncol 2026 — Advances in ommaya reservoir-based intrathecal therapy for leptomeningeal metastasis from non-small cell lung cancer a
• Weng et al. FrontOncol 2026 — Assessment of real-world surveillance strategies for patients undergoing systemic therapy for brain metastases
• Dee et al. JNatlCancerInst 2026 — Brain metastases among older people with cancer
• Li et al. OncolLett 2026 — Advances in cerebrospinal fluid biomarkers for the diagnosis, treatment and monitoring of leptomeningeal metastases (…

Basic-Oncogene and genetics

• Liao et al. CancerCell 2026 — Targeting TROP2 in drug-tolerant persister cells delays EGFR tyrosine kinase inhibitor resistance in non-small-cell
• Scaparone et al. CancerDiscov 2026 — EML4-ALK mediates resistance to KRAS G12C inhibition and induces an

Basic-Others

• Osarogiagbon et al. AmSocClinOncolEducBook 2026 — Optimal use of targeted therapy and immunotherapy in early-stage, resectable non-small cell lung cancer
• ODwyer et al. BMJOncol 2026 — Treatment of oligometastatic lung cancers new data, new drivers, new approaches
• Dymun et al. SciTranslMed 2026 — Clinicogenomic analysis of

Clinical-NSCLC-Driver-Other

• Kropf-Sanchen et al. ClinLungCancer 2026 — A retrospective, multicenter analysis within the national network genomic medicine lung cancer in germany to detect RET
• Luo et al. Med 2026 — Nsclc five trials to watch
• Wu et al. NEnglJMed 2026 — Selpercatinib in early-stage RET fusion-positive non-small-cell lung cancer

Clinical-NSCLC-EGFR

• Piotrowska et al. CancerDiscov 2026 — ELIOS A multicenter, molecular profiling study of patients with EGFR-mutant advanced non-small cell lung cancer treated
• Zhao et al. CancerTreatRev 2026 — Perioperative strategies for resectable EGFR-mutant NSCLC evidence hierarchy and clinical decision-making
• Lu et al. ClinLungCancer 2026 — Characteristics and clinical outcomes of de novo and acquired uncommon compound EGFR mutations in patients with
• Niu et al. FrontImmunol 2026 — Efficacy and mechanisms of immune checkpoint inhibitors in late-stage EGFR-mutated non-small cell lung cancer following
• Kim et al. FrontOncol 2026 — Paired ctDNA analysis reveals diverse resistance mechanisms to mobocertinib in EGFR exon 20 insertion NSCLC
• HARMONi et al. JAMA 2026 — A-Bispecific antibody ivonescimab added to chemotherapy in EGFR-variant non-small cell lung cancer the HARMONi-A
• Li et al. LancetOncol 2026 — Aumolertinib with or without chemotherapy in EGFR-mutated advanced non-small-cell lung cancer (AENEAS2) an open-label,
• Okamoto et al. LungCancer 2026 — Durvalumab plus etoposide-platinum in patients with epidermal growth factor receptor (EGFR)-mutated advanced NSCLC and
• Wang et al. LungCancer 2026 — Vebreltinib plus EGFR-TKI for EGFR-mutated NSCLC with MET-driven resistance A real-world study of chinese patients
• Janne et al. NEnglJMed 2026 — Survival with osimertinib plus chemotherapy in EGFR-mutated advanced nsclc
• Remon et al. NatRevClinOncol 2026 — Unresectable stage III non-small-cell lung cancer state of the art and challenges
• Zhao et al. NatRevClinOncol 2026 — Navigating the landscape of EGFR TKI resistance in EGFR-mutant NSCLC-mechanisms and evolving treatment approaches

Clinical-Novel modalities

• Jee et al. CancerDiscov 2026 — Deconvolving SARS-CoV-2 mRNA vaccine impact on immunotherapy-related survival
• Chen et al. FrontOncol 2026 — Evolution and recent advances in antibody-drug conjugate therapy for lung cancer a comprehensive systematic review

Clinical-Others

• Cowzer et al. ClinCancerRes 2026 — Molecular and clinical determinants of targeted therapy treatment in biliary tract cancer

Clinical-Supportive care

• Lin et al. TranslLungCancerRes 2026 — International consensus on severe lung cancer the second edition