Serum Tumor Marker Dynamics As Predictive Biomarkers In Nsclc Chemo-Immunotherapy And Mono-Immunotherapy Maintenance: A Registry-Based Descriptive Study

Objective: To evaluate serum tumor markers (STM) as predictive biomarkers in advanced non-small cell lung cancer (NSCLC) treated with chemo-immunotherapy.Methods: Patients having received platinum-based chemo-(CHT) and PD-1/PD-L1-directed immune checkpoint inhibitor (ICI) combination therapy were retrospectively followed. Carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), cytokeratin-19 fragments (CYFRA 21-1) and neuron specific enolase (NSE) were routinely measured at NSCLC diagnosis. The marker with the highest relative elevation was defined "leading STM", its change was assessed between CHT-ICI as well as mono-ICI maintenance initiation and the respective subsequent restaging. Corresponding computed tomography evaluations were analyzed using response evaluation criteria in solid tumors (RECIST). For CHT-ICI combination and subsequent mono-ICI-maintenance therapy, leading STM and RECIST response were evaluated regarding progression-free (PFS) and overall survival (OS) in Kaplan-Meier analyses.Results: Among 80 CHT-ICI patients (41% women, mean age 63 years), median PFS was 5 months (M;4,9), median OS was 15M (10,/). PFS was significantly (p=0.042) longer, when the leading STM had decreased at first restaging under CHT-ICI combination therapy (9M (5,12; n=41) vs 5M (3,6; n=16)). In the 54 (67.5%) patients who received subsequent mono-ICI maintenance therapy, STM decrease was similarly associated with significantly (p<0.001) longer PFS (16M (7,/; n=16) vs 3.5M (2,6; n=22)). Patients with radiologically stable or progressive disease and concomitant leading STM decrease had similar PFS in the CHT-ICI combination phase (4M (3,7; n=16) vs 4.5M (2,6; n=14)), but longer PFS in the mono-ICI maintenance setting (13M (7,16; n=10) vs 3M (2,4; n=17)). Median OS was not reached in most subgroups.Conclusion: Leading STM dynamics provide predictive biomarker information additional to radiological response evaluation patients receiving CHT-ICI combination therapy, especially in the mono-ICI maintenance setting.