150P IMreal cohort 5: Interim analysis (IA) of patients (pts) with PD-L1–high metastatic non-small cell lung cancer (mNSCLC) treated with first-line (1L) atezolizumab (atezo) in the real-world setting (RWS) of routine clinical practice

treatments in patients with MBM after failure from any prior systemic treatment in the (neo)-adjuvant or advanced setting.The efficacy of systemic treatment of MBM was measured as overall survival (OS) since the diagnosis of MBM.Systemic treatment was analysed according anti-PD1 monotherapy (nivolumab or pembrolizumab), anti-CTLA4 monotherapy (ipilimumab), combination therapy (ipilimumab plus nivolumab) and BRAF+/-MEK inhibitors.Results: A total of 2812 patients with MBM were included, 2267 patients were treatment nave, whereas 545 patients received any prior systemic treatment in the palliative or (neo)adjuvant setting.In patients who were treated with ICIs after developing MBM, patients without any prior treatment to MBM diagnosis (n=1266) had a longer median OS as compared to patients (n=277) with prior systemic treatment (17.6 months vs. 12.5 months, HR of 1.57 (95% CI 1.34-1.83,p<0.001) according to the multivariable Cox model adjusted for BRAF mutation, WHO-performance status and LDH).In patients who were treated with BRAF+/-MEK inhibitors for MBM, median OS was not significant different between patients without prior systemic treatment (n=852) and patients with prior systemic treatment (n=190) (10.0 months vs. 12.2 months, adjusted HR=0.97 (95% CI 0.83-1.14,p=0.70)). Conclusions:Patients with any prior systemic treatment have a poorer overall survival when treated with ICIs after the diagnosis of MBM, as compared to patients without any systemic treatment prior to diagnosis of MBM.However, prior systemic treatment did not significantly impact the OS for patients with MBM treated with BRAF+/-MEK inhibitors.The outcomes of this real-world cohort can assist treating physicians in individualizing treatment strategies and managing the expectations of patients with MBM.