RETRACTED: Tumor Microenvironment in Oral Cancer Following Neoadjuvant Pembrolizumab: Preliminary Analysis of the Histopathologic Findings

Abstract

Background: The tumor microenvironment (TME) of oral squamous cell carcinoma (OSCC) is associated with immune suppression, one of the pathways being the programmed death receptor 1 (PD-1) and its ligands (PD-L1/PD-L2). Checkpoint inhibitors of PD-1/PD-L1, like pembrolizumab, have been recently approved for treatment of OSCC. We described the histologic findings in OSCC following neoadjuvant pembrolizumab, including identification of immune-related cell populations and cancer-associated fibroblasts (CAFs).Materials and Methods: Patients with OSCC clinical stages 3 and 4 and a combined PD-L1 score >1 were randomized either to the standard oncologic protocol or to the pembrolizumab arm of MK-3475-689 study for Head and Neck, Lip, and Oral Cavity. The latter were given two standard doses of 200 mg of pembrolizumab, 3 weeks apart, and then underwent surgical oncologic procedure according to the initial stage. Sections from the resection specimens were analyzed for pathological response to pembrolizumab. Various populations of immune-related cells within the tumor microenvironment were characterized by immunohistochemistry, as were the CAFs.Results: Three patients who were randomized to the pembrolizumab study were described. One patient presented with a tongue SCC, the other two had SCC of the mandibular ridge with bony involvement. Only the patient with tongue SCC showed clinical complete response. Microscopically, the tumor was replaced by a granulomatous type of inflammation. Immunohistochemical stains revealed massive T cell rich (CD3+) infiltrate, with approximately equal amounts of CD4+ and CD8+ cells, numerous macrophages of CD68+ and CD163+ phenotypes; no CAFs were identified. The other two patients were regarded as non-responders as at least 50% of the tumor was viable. The tumor microenvironment of these tumors was generally associated with a lesser extent of inflammatory response compared to the tongue tumor, a variable CD4+/CD8+ ratio and presence of CAFs. Neither T regulatory cells (FOXP3+) nor natural killer cells (CD56+, CD57+) were identified in any of the cases.Conclusion: We showed that characterizing the specific populations of immune-related cells and CAFs after treatment with pembrolizumab, may add to our understanding of the tumor-TME interactions in this setting. These findings should be investigated in future studies on a larger number of patients.

Multimodal Dimension Reduction and Subtype Classification of Head and Neck Squamous Cell Tumors

“…Furthermore, approval of immunotherapy drugs such pembrolizumab and nivolumab for adjuvant treatment of recurrent and metastatic, or advanced unresectable HNSC, underscore the urgent need for research into tumor heterogeneity to better identify patients that are likely to be responders ( 74 , 75 ). Given the complex link between immunomodulation and tumor microenvironment, a more robust and accurate classification strategy will be beneficial ( 76 ). Although we used HNSC to test our multimodal strategy, our studies provide a generalizable framework that can be applied to any cancer or other diseases.…”