...Measurable or non-measurable, but evaluable disease using RECIST v1.1 Additional Inclusion Criteria for Phase 3 Only: • Histologically documented gastric or gastroesophageal junction (GEJ) adenocarcinoma (not amenable to curative therapy) • Radiographic imaging of the chest, abdomen and pelvis (computed tomography [CT] preferred, magnetic resonance imaging [MRI] acceptable) performed within 28 days (± 3 days) of treatment (C1D1) • FGFR2b overexpression as determined by a centrally performed IHC tissue test and/or FGFR2 gene amplification as determined by a centrally performed ctDNA blood based assay • Patient must be a candidate for mFOLFOX6 chemotherapy • No prior chemotherapy for metastatic or unresectable disease (except a maximum of 1 dose of mFOLFOX6 administered while waiting for results of FGFR2 testing during the Pre-Screening period) • If prior adjuvant or neo-adjuvant therapy (chemotherapy and/or chemoradiation) has been received, more than 6 months must have elapsed between the end of adjuvant therapy and the confirmation of radiographic disease progression`Phase 1 and Phase 2:1. ...

...- Fibroblast growth factor receptor 2b (FGFR2b) overexpression positive as determined by centrally performed immunohistochemistry (IHC) testing, based on tumor sample either archival (obtained within 6 months/180 days prior to signing pre-screening informed consent) or a fresh biopsy...

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...Prior adjuvant or neo-adjuvant therapy for localized disease is allowed, provided it has been completed more than 6 months prior to the first dose of study treatment.- Fibroblast growth factor receptor 2b (FGFR2b) overexpression as determined by centrally performed immunohistochemistry (IHC) testing -Adultos con adenocarcinoma gástrico o de la unión gastroesofágica documentado histológicamente, irresecable, localmente avanzada o metastásica (no susceptible de tratamiento curativo).-Estado funcional del Eastern Cooperative Oncology Group (ECOG) de 0 a 1.-Enfermedad medible o no medible, pero evaluable, según los criterios RECIST v. 1.1.-El sujeto debe ser candidato para recibir mFOLFOX6 y nivolumab.-Función orgánica adecuada tal como se define a continuación:•Recuento absoluto de neutrófilos ≥ 1,5 x 109/l.•Recuento plaquetario ≥ 100 x 109/l.•Hemoglobina ≥ 9 g/dl.•Aspartato aminotransferasa (AST) y ALT < 3 x LSN (o < 5 x límite superior de la normalidad [LSN] si hay afectación hepática). ...

ORR was 48.9% vs 34.1%. Treatment benefit was more pronounced in patients with FGFR2b+ ≥10%: PFS HR 0.28 (95% CI 0.13-0.57), OS HR 0.43 (95% CI 0.22-0.86)….In East Asian pts (N=89) with FGFR2b+ advanced or metastatic G/GEJC, bema+mFOLFOX6 continued to show clinically meaningful outcomes over pbo+mFOLFOX6 after 24mo of follow-up.

Patients with FGFR2b overexpression irrespective of ctDNA gene amplification benefited from bema: IHC+/ctDNA- PFS hazard ratio (HR) 0.63 (95% CI 0.4, 0.99), OS HR 0.66 (95% CI 0.39, 1.12....Pts with overexpression of FGFR2b even without ctDNA amplification demonstrated a benefit from the addition of bema to mFOLFOX6….

Improved efficacy was observed across all 3 endpoints (PFS, OS, ORR) with increasing levels of overexpression of FGFR2b on tumor cells....the addition of bema to mFOLFOX6 led to clinically meaningful and statistically significant improvements in PFS, OS and ORR.

Five (17.9%; 95% CI, 6.1% to 36.9%) of 28 patients with high FGFR2b-overexpressing GEA had a confirmed partial response….bemarituzumab seems to be well tolerated and demonstrated single-agent activity as late-line therapy in patients with advanced-stage GEA.