Background: The addition of IO to chemotherapy for first-line treatment of SCLC has improved median overall survival (OS). No OS difference was observed in patients with brain metastases in the clinical trial setting, however outcomes need to be assessed in the non-clinical trial setting. Methods: This retrospective study included 121 patients with SCLC who received ICI-based therapy between 2016-2022 at the Ohio State University. Medical records were extracted via chart review and data was collected in REDCap. Clinical characteristics were summarized using descriptive statistics and compared between patients with and without brain metastasis using Kruskal-Wallis test (continuous outcomes) and Fisher’s exact test (categorical outcomes). Kaplan-Meier survival analysis were used to assess the survival outcomes. All statistical analysis was done in SAS 9.4. Results: Median age at diagnosis was 64.7 years (IQR: 60.1-69.7). Our cohort included 53.8% males and 46.2% females, majority (89.1%) of patients were white, 7.6% were African Americans. Baseline ECOG status was 0 (11.9 %), 1(50%) and > = 2 (38.1%). 97% were current or former smokers. Most had extensive stage disease (96.6%) at diagnosis. Most common sites of metastasis at diagnosis were liver (46.2%), bone (42.9%), brain (35.3%), lymph nodes (34.7%). All patients received first line chemotherapy with atezolizumab (atezo), 40% received atezo with cycle one of chemotherapy, 47% had atezo added with the second cycle, and 13% had atezo added after cycle 2. Median OS for all patients was 9.5 months (95% CI 8.1, 12.9 months); 81% had disease progression at a median follow up of 8.5 months (95% CI 5.2-16.8). 52% patients received second line therapy, 18% received third line and 12% received fourth line and beyond. Subsequent therapies included chemotherapy (29.8%), immunotherapy (4.1%) and clinical trials (14.1%). CNS progression was seen in 47.9%. Median OS for patients with baseline brain metastasis was not significantly different than patients without,11.8 months (95% CI 8-17.6 months) compared to 8.3 months (95% CI 6.2-12.9 months), p:0.26. For patients without baseline brain metastases, median time to developing brain metastasis from starting chemo-IO was 7.3 months [IQR: 5.3-14.1 months]. There was no significant association between the development of brain metastasis and age, sex, or race. At CNS progression 36.4% received SBRT, 18.2% received WBRT. Conclusions: Median overall survival in this cohort was shorter than what has been reported in the phase 3 trials with first line chemo-IO. OS for patients with brain metastases did not differ significantly than for those without, and there was a higher rate of SRS/SBRT versus WBRT. Just over half of patients received subsequent lines of therapy highlighting the need for continued improvement in treatment options for SCLC.