PD-L1 expression in inflammatory myofibroblastic tumors.

Area of Science:

• Oncology
• Immunology
• Pathology

Background:

• Inflammatory myofibroblastic tumors (IMT) are rare mesenchymal neoplasms with variable clinical behavior.
• Limited therapeutic options exist for IMT, especially for those resistant to tyrosine kinase inhibitors.
• The role of immune checkpoint proteins, like PD-L1, in IMT pathogenesis and treatment is largely unexplored.

Purpose of the Study:

• To investigate the expression patterns of PD-L1 in IMT.
• To determine if PD-L1 expression correlates with clinicopathologic features and ALK status.
• To assess the potential of PD-L1 as a predictive biomarker for immunotherapy in IMT.

Main Methods:

• PD-L1 expression (clone SP142) was analyzed in 35 IMT specimens.
• Tumor and immune cell PD-L1 positivity was evaluated, along with adaptive vs. constitutive expression patterns.
• CD8+ T cell infiltrates and ALK status were assessed and correlated with PD-L1 expression and clinical data.

Main Results:

• PD-L1 expression was detected in 69% of tumor cells and 80% of immune cells.
• Adaptive PD-L1 expression was observed in 96% of PD-L1 positive tumors and was associated with increased CD8+ T cell infiltration.
• Constitutive PD-L1 expression correlated with larger tumor size.

Conclusions:

• Inflammatory myofibroblastic tumors frequently exhibit both constitutive and adaptive PD-L1 expression.
• Adaptive PD-L1 expression, associated with increased CD8+ T cell infiltration, may predict response to anti-PD-1/PD-L1 therapies.
• These findings support further investigation of PD-1/PD-L1 blockade as a therapeutic strategy for IMT.