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Thymic carcinomas are aggressive and difficult to treat a subset of thymic epithelial tumours that represent a heterogeneous group of rare intrathoracic malignancies. The treatment strategy of thymic carcinomas is based on whether surgical resection may be achieved, which represents the most significant favourable prognostic factor on survival. For this study, we took advantage of the unique prospective Réseau tumeurs THYMiques et Cancer (RYTHMIC) database to describe baseline characteristics, analyse treatment strategies in light of existing guidelines and provide landmark patient outcomes data with regards to response and survival of patients in a real-life clinical practice setting.Inclusion criteria for this analysis were the following: (1) histologically-confirmed thymic carcinomas - excluding neuroendocrine tumours-after pathological review by the RYTHMIC pathology panel, (2) discussion of the case at the RYTHMIC multidisciplinary tumour board, (3) at least one active treatment modality.A total of 213 patients were analysed. Overall, 60 (28%) patients were considered as surgical candidates upfront, 91 (43%) patients received primary chemotherapy, and 62 (29%) patients received exclusive chemotherapy. Median overall survival (OS) was 49.2 months (IC95%: 34.8-63.6); OS was significantly longer in patients with a lower stage at diagnosis (p 0.001), who were operated on upfront, as opposed to patients who received primary or exclusive chemotherapy (p 0.001). Surgery, conducted upfront or after primary chemotherapy, was significantly associated with more prolonged OS (p 0.001); complete resection and postoperative radiotherapy were also predictors of better outcome (p = 0.018 and p = 0.051, respectively).Our cohort is the first to analyse in-depth outcomes and treatment strategies in a prospective cohort of consecutive patients with thymic carcinoma. While we confirm the major prognostic impact of surgery, our data highlight the need for optimised multidisciplinary management and innovative therapies as the survival of patients remains limited.

Introduction The systematic assessment of anti-programmed cell death ligand 1 (PD-L1) expression by immunohistochemistry (IHC) in lung adenocarcinomas is becoming standard practice. However, the assessment of PD-L1 expression on small tissue specimens needs to be evaluated and the association with other features more thoroughly analyzed. Methods This retrospective single center study evaluated the immunohistochemical expression of the SP263 anti-PD-L1 antibody on tissue microarrays (TMA) of 152 surgically resected lung adenocarcinomas, using a 25% positivity threshold. The positive cases and 50 randomly chosen negative cases in tissue microarray (TMA) were reassessed on whole tissue sections. The results were correlated to clinical, histopathological and to molecular data obtained through the screening of 214 mutations in 26 genes (LungCarta panel, Agena Biosciences). Results Among 152 primary lung adenocarcinomas, 19 cases (13%) showed PD-L1 expression. The agreement between TMA and whole tissue sections was 89%, specificity was 97%. PD-L1 expression was correlated to RAS mutations (p = .04), RAS/TP53 co-mutations (p = .01) and to the solid or acinar subtype (p = .048). Conclusions With the SP263 PD-L1 antibody, small samples appear as a reliable means to evaluate the PD-L1 status in lung adenocarcinoma. The association between PD-L1 expression and RAS/TP53 mutations may have clinical relevance to predict the efficacy of PD-1/PD-L1 immune checkpoints inhibitors.

9072 Background: Thymic carcinomas are an aggressive and difficult to treat subset of thymic epithelial tumors (TETs) that represent a heterogeneous group of rare intrathoracic malignancies. Most of the current knowledge and guidelines tumors rely on surgically-oriented databases focusing on early-stage disease, and small prospective, single-arm trials conducted in metastatic thymic carcinomas, mostly in a refractory, late-line setting. “Réseau tumeurs THYMiques et Cancer” (RYTHMIC) is the nationwide network for TETs in France. The management of any patient has to be systematically discussed on a real-time basis at a national multidisciplinary tumor board; a database is hosted by the French Thoracic Cancer Intergroup (IFCT). Methods: We took advantage of the RYTHMIC prospective database to describe baseline characteristics, analyze treatment strategies, and provide landmark outcomes in a cohort of consecutive patients with thymic carcinoma. The inclusion period was January 2012 to April 2017. Results: A total of 213 patients were analyzed. Overall, 60 (28%) patients were considered as surgical candidates upfront, 91 (43%) received primary chemotherapy, and 62 (29%) received exclusive chemotherapy. Median OS was 49.2 months (IC95%: 34.8-63.6); OS was significantly longer in patients with a lower stage at diagnosis (p < 0.001), who were operated on upfront, as opposed to patients who received primary or exclusive chemotherapy (p < 0.001). Surgery, conducted upfront or after primary chemotherapy, was significantly associated with more prolonged OS (p < 0.001); complete resection and postoperative radiotherapy were also predictors of better outcome (p = 0.018 and p = 0.081, respectively). Exclusive chemotherapy was delivered to 62 patients with advanced disease, who all received platinum-based regimen as first-line treatment; PAC regimen was delivered to 66% of patients. Best objective response to first-line chemotherapy was partial response in 33 (53%) patients. Median PFS was 8.0 months (IC95%: 5.0-11.1). Median OS was 32.9 months (IC95%: 20.6-45.1). Response to first-line chemotherapy and squamous histology were the only significant predictors of OS (p = 0.002 and p = 0.040, respectively). Conclusions: Our cohort is the first to analyze in depth outcomes and treatment strategies in a prospective cohort of consecutive patients with thymic carcinoma. While we confirm the major prognostic impact of surgery, our data highlight the need for optimized multidisciplinary management and innovative therapies as the survival of patients remains limited.