Primary Salivary Clear Cell Carcinoma with Response to Checkpoint Inhibition: Case Report and Review of the Literature

Introduction: Primary salivary clear cell carcinoma is a rare tumor of the minor salivary glands that is often seen as low-grade and responsive to resection. Limited data exists for its response to systemic chemotherapy or immune therapy. Case Presentation: A 76-year-old male presented with recurrent, widely metastatic salivary CCC over three years after local resection with bilateral selective neck dissections. Advanced imaging showed biopsy confirmed metastasis to the omentum, lungs, pleural effusion and lymph nodes. Stable disease was achieved with carboplatin/paclitaxel therapy, but treatment was not tolerated by the patient due to side effects. Patient has been treated with single agent pembrolizumab for 12 cycles with continued disease control and improvement in effusion. Conclusion: Despite the low immunogenicity of this tumor, a clinically positive response was achieved with PD-(L)1 inhibition. More research is needed to identify systemic targeted therapies for CCC and tumors with low immunogenicity.