Clinical features, treatment, and survival outcome of primary pulmonary NUT midline carcinoma.

<bold>Objective: </bold>NUT midline carcinoma (NMC), a rare type of squamous cell carcinoma, is genetically characterised by NUT midline carcinoma family member 1 (NUTM1) gene rearrangement. NMC can arise from the lungs; however, there is no standard for the management of primary pulmonary NMC. This study aimed to confirm the clinical features and report the treatments, especially with immune checkpoint inhibitors (ICIs), and outcomes of patients with primary pulmonary NMC.<bold>Methods: </bold>A retrospective review of patients with primary pulmonary NMC was performed in the First Affiliated Hospital of Guangzhou Medical University between January 2015 and December 2018. Clinical manifestations as well as radiographic and pathological findings were recorded. Whole-exome sequencing (WES), a predictor for ICI response, was used to determine the tumour mutational burden (TMB). Treatments, especially by immune checkpoint blockade, and patient survival were analysed.<bold>Results: </bold>Seven patients with primary pulmonary mass (four men and three women) with a mean age of 42 years (range, 23-74) who were diagnosed with NMC according to NUT immunohistochemistry staining were included for analysis. One patient had a rare fusion of CHRM5-NUTM1 by tumour sequencing. A wide range of TMB (1.75-73.81 mutations/Mbp) was observed. The initial treatments included chemotherapy (5/7, 71.4%), surgery (1/7, 14.3%), and radiotherapy (1/7, 14.3%). Five patients (5/7, 71.4%) received ICIs (programmed cell death protein 1 [PD1]/programmed cell death ligand 1 [PDL1] monoclonal antibody) as second- or higher-line treatments. The median overall survival (OS) was 4.1 months (range, 1.5-26.7 months).<bold>Conclusions: </bold>Patients with primary pulmonary NMC have a poor prognosis and chemotherapy is often preferred. Checkpoint immunotherapy is a good option as the second- or higher-line treatment. TMB seems to be not associated with OS. [ABSTRACT FROM AUTHOR]