Ivonescimab (AK112, anti-PD-1/VEGF bispecific antibody)
一行要約
Ivonescimab (AK112) は anti-PD-1 + anti-VEGF-A の bispecific tetravalent IgG-like antibody (Akeso 開発, 米国は Summit Therapeutics ライセンス)。Tumor microenvironment 内で PD-1 と VEGF-A を同時遮断し、IO + 抗血管新生の dual mechanism を 1 分子で達成する設計。HARMONi-2 (Chinese phase III) で 1L PD-L1+ NSCLC で pembrolizumab を PFS で上回る結果を示し、global 1L NSCLC 標準を揺るがす landmark。Bispecific antibody class の novel modality として、dual checkpoint / receptor-targeting bispecific と並ぶ next-generation IO design の代表例。
主要エビデンス
- HARMONi-2 (Zhou 2024 World Lung Conference): 1L PD-L1 ≥1% NSCLC で ivonescimab vs pembrolizumab,** PFS benefit (HR 0.51)**, OS data immature。China-only single-region trial、global generalizability が central question
- HARMONi-A: 2L+ EGFR-mutant NSCLC (post-TKI) で ivonescimab + chemo vs pbo + chemo, PFS benefit (Fang 2024 JAMA)
- HARMONi-3 (global, ongoing): NSCLC 1L global registration trial (Summit Therapeutics, vs pembrolizumab + chemo), 結果を IO standard rewrite の potential
- Pre-clinical: PD-1 binding affinity が VEGF-A 結合下で増強 (cooperative binding), tumor-localized dual blockade rationale
メカニズム
(1) Tetravalent IgG-like 構造で 2 valency anti-PD-1 + 2 valency anti-VEGF-A、(2) tumor microenvironment 内で PD-1 と VEGF-A 同時遮断 → IO restoration + anti-angiogenic / vascular normalization (CD8 infiltration 改善, hypoxia / Treg 抑制), (3) cooperative binding: VEGF-A 結合下で PD-1 binding が enhance、tumor-localized concentration up、(4) bispecific architecture が systemic exposure を抑え irAE / hypertension を期待的に軽減 (clinical data でも safety profile favorable)。
VEGF axis の immune-regulatory effect (vascular normalization → CD8 infiltration up, MDSC/Treg recruitment 抑制) と PD-1 blockade の synergy が long-known concept (atezolizumab + bevacizumab IMpower150 等) を 1 分子で実装。
臨床位置づけ
HARMONi-2 で pembrolizumab を超える 1L PFS benefit は、IO standard を 10 年安定的に占めてきた pembrolizumab pillar への challenge として oncology community に大きな impact。ただし (1) China-only single-region trial で global generalizability 不明、(2) OS data immature、(3) HARMONi-3 global trial 結果 待ち。HARMONi-A (EGFR-mutant post-TKI) は新たな 2L EGFR-mutant standard を形成する可能性。Adverse event: hypertension / proteinuria / bleeding (VEGF class 共通) と immune-related (PD-1 共通)。Bispecific class として MARIPOSA (amivantamab, EGFR×MET) / DeLLphi-301 (tarlatamab, DLL3×CD3) と並ぶ novel modality 革命の representative。
Open Questions
- Global generalizability: HARMONi-3 で China 結果が再現するか
- OS endpoint: PFS → OS translation
- EGFR-mutant subpopulation での optimal sequencing (HARMONi-A 結果と T-DXd / Dato-DXd / amivantamab との位置関係)
- Bispecific class design comparison: PD-1×VEGF (ivonescimab) vs PD-1×LAG-3 (RO7247669) vs PD-L1×4-1BB の相対 efficacy / safety
- Brain metastasis efficacy: VEGF blockade の vascular normalization が brain met IO に与える impact
- Combination: ivonescimab + chemo / + ADC の potential
関連エンティティ
- 関連経路: PD-1-PD-L1-signaling-pathway / VEGF-angiogenesis-pathway / CTLA-4-B7-signaling-pathway
- 関連遺伝子: PD-L1 / VEGFA / EGFR
- 関連薬剤: PD-1-inhibitor / PD-L1-inhibitor / anti-VEGF-antibody / VEGFR-TKI / BiTE-bispecific / EGFR-MET-bispecific / Pembrolizumab / Durvalumab
- 関連 trial: KEYNOTE-024 / KEYNOTE-189 / IMpower150 / MARIPOSA
- 関連概念: IO-primary-resistance / Tumor-angiogenesis / Vascular-normalization / Bispecific-modality-design