Purpose of ReviewThree biologics targeting type 2 inflammation have been approved for the treatment of severe and uncontrolled chronic rhinosinusitis with nasal polyps (CRSwNP). Nevertheless, around 40-60% of patients do not respond well to these biological treatments. Selecting appropriate patients is crucial to improve treatment outcome of biologics. This review summarizes the literature data on type 2 biomarkers, with a specific focus on the indication to biologics for severe CRSwNP.Recent FindingsNo consensus has been reached on how to define mucosal type 2 inflammation in CRSwNP. Clinical markers (e.g., 22-item Sino-nasal Outcome Test (SNOT-22) score, Lund-Mackay CT score (LMS), ethmoid/maxillary sinus CT score, and CT-radiomics), nasal secretion biomarkers (e.g., eosinophil cationic protein and interleukin-5), blood and nasal cytology eosinophil counts, and nasal swab eosinophil peroxidase activity have been reported to be associated with type 2 inflammation in CRSwNP. The time duration since the last surgery, SNOT-22 score at 1 week of treatment, and baseline serum osteoprotegerin levels might indicate the response to dupilumab. LMS and asthma control test scores were found to have moderate predictive value for acceptable improvement after 24-week treatment of omalizumab. High blood eosinophil levels at baseline were associated with treatment response to mepolizumab and benralizumab.SummaryAlthough several clinical and biological markers might be associated with type 2 inflammation and response to biologics in patients with CRSwNP, their validity requires further investigation. Identifying clinically applicable biomarkers for biologic treatment holds significant promise for advancing personalized approaches to biologics and optimizing treatment outcomes for patients with CRSwNP.