Programmed cell death ligand-1 (PD-L1) expression in desmoid tumors: a retrospective study

Area of Science:

• Oncology
• Immunology
• Pathology

Background:

• Desmoid tumors are rare, locally aggressive fibroblastic proliferations lacking metastatic potential but with high recurrence rates.
• Genetic mutations in CTNNB1 or APC genes characterize desmoid tumors.
• While watchful waiting is suitable for asymptomatic cases, medical therapy is an option for symptomatic patients with high surgical morbidity risks.

Purpose of the Study:

• To assess the expression of programmed death-ligand 1 (PD-L1) in desmoid tumors.
• To evaluate the potential efficacy of anti-PD-1/PD-L1 therapy in desmoid tumor treatment.

Main Methods:

• Immunohistochemical staining for PD-L1 expression was performed on biopsy and resection samples from 18 desmoid tumor patients.
• Leica Bond® automated stainer was utilized for antibody staining.

Main Results:

• No desmoid tumor cells exhibited positive PD-L1 staining in any of the 18 specimens.
• All specimens contained intratumoral lymphocytes.
• Five of the specimens showed positive PD-L1 staining in intratumoral lymphocytes.

Conclusions:

• The absence of PD-L1 expression on desmoid tumor cells suggests that anti-PD-1/PD-L1 therapy is unlikely to be a beneficial treatment strategy.
• The presence of PD-L1 positive intratumoral lymphocytes indicates a potential area for future research in desmoid tumor immunotherapy.