Pembrolizumab In A Patient With Lung Sarcomatoid Carcinoma Resulted In Rheumatoid Arthritis And Limited Benefit

Lung sarcomatoid carcinoma (SC) is a type of non-small cell lung carcinoma (NSCLC) with poor prognosis and chemo-resistance. Pembrolizumab achieved longer progression-free survival and overall survival than chemotherapy if PD-L1 expression surpasses 50% in NSCLC. However, its efficacy in lung SC is still unknown. We report a female patient with short efficacy with pembrolizumab, but occurrence of confirmed rheumatoid arthritis (RA) in lung SC. RA triggered by pembrolizumab is rarely reported. This patient had no RA before but had a positive family history. This case showed the efficacy of pembrolizumab in lung SC with high PD-L1 expression, and clinical trials containing more cases should be warranted to further evaluate its effect on lung SC. More importantly, oncologists should pay attention to screening of immune-associated family history and indices before anti-PD-1/PD-L1 therapy.