Efficacy of immune check point inhibitors (ICIs) in metastatic gastric or gastroesophageal junction (GEJ) cancer by patient subgroups: A systemic review and meta-analysis.

Abstract

e16587 Background: Patients with metastatic gastric or GEJ cancer have short duration of response to chemotherapy and poor outcome. Treatment with ICIs has been investigated for this population with inconsistent results. It is uncertain whether the effect of ICIs is comparable in different subgroups. Methods: Randomized controlled trials (RCTs) that compared standard treatment to treatment with ICIs, either as a monotherapy or in combination with chemotherapy, for metastatic gastric or GEJ cancer were identified. Hazard ratios (HRs) and 95% confidence intervals (CI) for overall survival (OS) were extracted and pooled in a meta-analysis using generic inverse variance and random effects modelling. Pre-specified subgroups included: patients’ age at time of randomization (age < /≤ 65 years versus ≥/ > 65 years), gender (female versus male), ethnicity (Asians versus the rest of the world), Eastern Cooperative Oncology Group performance status (0 versus 1), primary tumor location (gastric versus GEJ) and histological subtype (diffuse versus other subtypes). Data on progression free survival (PFS) and on OS in patients with programmed death ligand (PDL1) positive were also collected. Results: Four RCTs comprising 1,765 patients were analyzed. Treatment with ICIs compared to standard therapy did not significantly improve OS (HR = 0.84, 95% CI 0.66-1.07, p = 0.17), PFS (HR = 1.22, 95% CI 0.75-1.96, p = 0.52), or OS in patients with PDL1 positive disease (HR = 0.86, 95% CI 0.73-1.02, p = 0.08). The effect of ICIs on OS was similar in all subgroups. Non-significantly greater effect sizes were seen in younger patients (HR = 0.82 versus 0.86, p for subgroup difference 0.80), male (HR = 0.81 versus 0.97, p = 0.32), performance status 0 (HR = 0.84 versus 0.88, p = 0.81), GEJ tumors (HR = 0.76 versus 0.89, p = 0.44) and non-diffuse subtype (HR = 0.71 versus 0.79, p = 0.62). Conclusions: Compared to standard treatment, ICIs in metastatic gastric or GEJ cancer did not improve OS significantly. As none of the evaluated subgroups has shown increased magnitude of effect to ICIs, other biomarkers for ICIs response are desired in order to optimize the risk versus benefit balance of these patients.