Association of Macrophage Migration Inhibitory Factor (MIF) with Therapy Response and Clinical Outcomes in HPV-Related Head and Neck Squamous Cell Carcinoma: A Preliminary Report

Background: Macrophage migration inhibitory factor (MIF) is a critical modulator of the tumor immune microenvironment (TME). Its clinical significance in head and neck squamous cell carcinoma (HNSCC) remains controversial because of HPV-dependent tumor biology and the limitations of single-timepoint biomarker assessments. This preliminary study evaluates whether dynamic changes in circulating MIF (ΔMIF) in an HPV-stratified longitudinal cohort reflect disease severity and treatment response. Methods: Ninety-six serial serum samples were analyzed from 27 HNSCC patients (22 HPV-positive, 5 HPV-negative) from diagnosis through therapy and follow-up. Serum MIF and anti-HPV16 E7 IgG were quantified by ELISA, and ΔMIF was defined as the change in MIF concentration between consecutive visits. Results: Baseline MIF did not correlate with clinical stage in the total cohort (p = 0.63). However, 56% of HPV-positive patients exhibited a positive correlation between elevated MIF and advanced stage. Following chemoradiotherapy, the HPV-negative group showed a consistent and significant decline in MIF (mean ΔMIF = −1.23, p = 0.031), corresponding with no evidence of disease (NED). In contrast, the HPV-positive group showed heterogeneous trajectories (mean ΔMIF = +0.21, p = 0.94), with several patients demonstrating paradoxical declines in MIF during active disease or relapse, followed by recovery upon reaching NED. In select cases, MIF dynamics were closely synchronized with anti-E7 IgG levels. Conclusions: Serum MIF dynamics are strongly dependent on HPV status. While MIF serves as a reliable therapy-monitoring marker in HPV-negative HNSCC, it may play a complex and paradoxical immunomodulatory role in HPV-positive disease. These preliminary findings support the need for larger prospective, HPV-stratified trials.