Hsu, Charles C.

TPS9082 Background: Limited stage small cell lung cancer (LS-SCLC) is treated with standard of care platinum/etoposide (EP) and thoracic radiation therapy (TRT) with curative intent, however the majority of patients are not cured and median overall survival is approximately 30 months. Addition of atezolizumab to chemotherapy in extensive stage SCLC has improved progression free and overall survival in a non-curative setting leading to hope that addition of an immune checkpoint inhibitor to standard chemoradiotherapy could benefit LS-SCLC patients. LU005 is a randomized phase II/III trial of standard concurrent chemoradiation with or without atezolizumab for patients with LS-SCLC. Methods: Patients are randomly assigned in a 1:1 ratio to standard EP chemotherapy with concurrent TRT (45 Gy BID or 66 Gy QD) with or without atezolizumab beginning concurrently with TRT, and continued every 3 weeks for up to 12 months. Eligible patients have LS-SCLC, PS 0-2, adequate organ function, no concerning comorbidities (including no active autoimmune disease) and are eligible for TRT. Patients are randomized prior to their second cycle of EP and thoracic radiation begins with the second overall cycle of chemotherapy (first cycle of study therapy) in both treatment arms. Prophylactic cranial radiation (PCI) is recommended for patients who respond to treatment. The phase II/III primary endpoints are progression free (PFS) and overall survival (OS) respectively. Secondary endpoints include objective response rates, local and distant disease control, and quality of life/patient reported outcomes assessment. Translational science component includes blood and tissue based immune related assays. This study activated in May 2019. 50 of 506 planned patients have been accrued as of 2/1/2020. Supported by grants U10CA180868 (NRG Oncology Operations), U10CA180822 (NRG Oncology SDMC), U23CA180803 (IROC) from the National Cancer Institute (NCI) and Genentech. *Authors Ross and Higgins are co-first authors and contributed equally to this work. Clinical trial information: NCT03811002.

251 Background: To assess the effect of adjuvant therapy in gallbladder adenocarcinoma (GBC). Methods: Retrospective review was conducted at five institutions to identify pts who had surgery for confirmed dx of GBC from 1985-2008 (N = 189). Pts were excluded if they had chemo alone (N = 8), path other than adenoca (N= 7), carcinoma in situ (N=1), < 30 days of follow-up (N = 2), or missing data (N=14). Of the remaining 156 pts, 58 received surgery only and 98 received adj RT ± chemo. Kaplan-Meier was used for overall survival (OS) and Cox proportional hazards to compare risk factors. Results: Median age of dx was 64.4, 68.0% were female, 37.9% had ≥ stage 2b, 37.2% had + nodes, and 32.1% had + margins. Overall, 35.9% of the patients had simple cholecystectomy (SC) only and 64.1% had radical resection (ER). mOS for pts treated with surgery alone was 49.7 months (95% CI: 24.8 to Inf). On univariate analysis, + margins (HR 2.72, p<0.001) was associated with worse OS, whereas ER compared to SC improved survival in both univariate (HR 0.46, p<0.001) and multivariate (HR 0.53, p=0.033) analyses after adjusting for node/margins, T-stage, adj RT, age, gender, and institution. mOS for the entire cohort vs. adj RT (median 50.4 Gy) ± chemo was 30.7 months (95% CI: 19.2 to 46.9) vs. 26.9 months (95% CI: 15.5 to 39.1). But, compared to surgery alone, the adj group was more likely to have had node +, margin +, or T-stage 3+ (all p<0.001). The adj RT group was also less likely than surgery alone pts to have undergone ER (p = 0.007). On multivariate analysis, decreased OS was also found for node + (HR 2.09, p=0.004), margin + (HR 1.84, p=0.043), and T3/T4 disease (HR 2.37, p=0.002). After adjusting for surgical extent, node, margin, T stage, age, gender, and institution, there was improved OS with adj therapy (HR: 0.43, p = 0.020). When stratified by surgical extent, the risk estimate for adj RT improved OS among those with SC (n=56; HR 0.20, p=0.135) and ER (n=100; HR 0.46, p=0.067), but was not statistically significant. Conclusions: ER was associated with improved OS, whereas node/margin+ and T-stage 3+ were associated with worse survival. In multivariate analysis, adj RT improved OS after surgery. Given the poor prognosis of GBC patients with advanced disease, consideration of adj therapy is appropriate. No significant financial relationships to disclose.