Pure Apocrine Intraductal Carcinoma of Salivary Glands: Reassessment of Molecular Underpinnings and Behavior.

BACKGROUND: Intraductal carcinoma (IDC) of the salivary glands is a confounding entity, our understanding of which continues to evolve. At least four forms have been elucidated based on histomorphology, immunophenotype, and molecular profile: (1) intercalated duct-like, S100/SOX10+ with frequent NCOA4::RET fusions; (2) oncocytic, S100/SOX10+ with TRIM33::RET, NCOA4::RET, and BRAF V600E; (3) apocrine, AR+ with PI3 kinase pathway mutations; and (4) mixed/hybrid intercalated duct-like/apocrine, with S100/SOX10+ and AR+ areas and frequent TRIM27::RET. The revelation that myoepithelial cells harbor the same fusion as luminal cells suggested that fusion-positive cases are not in situ carcinomas as previously believed. To this point, purely apocrine IDC with entirely intraductal growth has not been found to harbor fusions, but very few cases have been tested. METHODS: IDCs with pure apocrine morphology, entirely intraductal growth, and no precursor lesion (pleomorphic adenoma or sclerosing polycystic adenoma) were retrieved from the authors' archives. Several immunostains (S100, SOX10, GCDFP-15, AR, p40/SMA) and targeted next generation sequencing (NGS) panel including 1425 cancer-related genes were performed. RESULTS: Seven entirely IDC with pure apocrine type were collected. The cases arose in the parotid glands (mean, 1.9 cm) of 5 men and 2 women ranging from 51 to 84 years (mean, 69.7 years). Histologically, tumors consisted of rounded to angulated ductal cysts lined by epithelial cells with abundant finely granular eosinophilic cytoplasm and large nuclei with prominent nucleoli. Pleomorphism was mild to moderate, the mitotic rate was low, and necrosis was absent. Conventionally invasive foci or areas of intercalated duct-like morphology were not identified. In all cases, luminal cells were diffusely positive for AR and GCDFP-15 while negative for S100/SOX10, and the ducts were completely surrounded by myoepithelial cells highlighted by p40 and SMA. Molecular analysis was successful in 6 cases. Three harbored fusions: one with NCOA4::RET, another with STRN::ALK and one with both CDKN2A::CNTRL and TANC1::YY1AP1. The three fusion-negative cases all harbored HRAS mutations; additional mutations (PIK3CA, SPEN, ATM) were found in 2 of 3 cases. All patients were treated by surgery alone. Six of them are currently free of disease (follow up 12-190 months), but the case harboring NCOA4::RET developed lymph nodes metastasis in the form of a fusion-positive invasive salivary duct carcinoma. CONCLUSIONS: Purely apocrine IDC is a heterogeneous disease. A subset seems to be genetically similar to salivary duct carcinoma and may indeed represent carcinoma in situ. The other group harbors fusions, similar to other forms of IDC. Moreover, the occurrence of lymph node metastasis discredits the idea that any fusion-positive IDC with a complete myoepithelial cell layer has no metastatic potential. With the wide use of RET-and ALK-based targeted therapies, our findings further underscore the importance of fusion analysis for IDC.

Inter-assay reliability of programmed cell death-ligand 1 in head and neck squamous cell carcinoma.

OBJECTIVES: The programmed cell death-ligand 1 (PD-L1) 22C3 pharmDx assay is used as a companion diagnostic test to select head and neck squamous cell carcinoma (HNSCC) patients that may benefit from treatment with the checkpoint inhibitor pembrolizumab. Because the Dako platform is not universally available, we studied the performance of a 22C3 laboratory developed test (LDT) performed on a Ventana BenchMark Ultra compared to the 22C3 pharmDx assay. MATERIALS AND METHODS: Serial sections from tissue micro arrays (TMAs) containing tumour tissue from 97 HNSCC patients were stained with the 22C3 pharmDx assay and 22C3 LDT. All TMA cores were scored by three dedicated head and neck pathologists for PD-L1 expression. RESULTS: Substantial interobserver agreement was reported for both the standardized 22C3 pharmDx assay and the 22C3 LDT (respectively Fleiss' κ 0.62, 95% CI 0.57-0.67 and 0.63, 95% CI 0.58-0.68). Concordance between the assays was almost perfect on core and patient level (respectively Weighted κ 0.84, 95% CI 0.79-0.89 and 0.84, 95% CI 0.75-0.92). Intratumor heterogeneity between the cores per patient case was similar in both assays. CONCLUSION: After validation a 22C3 LDT is non-inferior to the standardized 22C3 pharmDx assay and can be safely used to select HNSCC patients for pembrolizumab treatment.

A Standardized Framework for Fluorescence-Guided Margin Assessment for Head and Neck Cancer Using a Tumor Acidosis Sensitive Optical Imaging Agent.

PURPOSE: Intra-operative management of the surgical margin in patients diagnosed with head and neck squamous cell carcinoma (HNSCC) remains challenging as surgeons still have to rely on visual and tactile information. Fluorescence-guided surgery using tumor-specific imaging agents can assist in clinical decision-making. However, a standardized imaging methodology is lacking. In this study, we determined whether a standardized, specimen-driven, fluorescence imaging framework using ONM-100 could assist in clinical decision-making during surgery. PROCEDURES: Thirteen patients with histologically proven HNSCC were included in this clinical study and received ONM-100 24 ± 8 h before surgery. Fluorescence images of the excised surgical specimen and of the surgical cavity were analyzed. A fluorescent lesion with a tumor-to-background ratio (TBR) > 1.5 was considered fluorescence-positive and correlated to standard of care (SOC) histopathology. RESULTS: All six tumor-positive surgical margins were detected immediately after excision using fluorescence-guided intra-operative imaging. Postoperative analysis showed a median TBR (±IQR) of the fluorescent lesions on the resection margin of 3.36 ± 1.62. Three fluorescence-positive lesions in the surgical cavity were biopsied and showed occult carcinoma and severe dysplasia, and a false-positive fluorescence lesion. CONCLUSION: Our specimen-driven fluorescence framework using a novel, pH-activatable, fluorescent imaging agent could assist in reliable and real-time adequate clinical decision-making showing that a fluorescent lesion on the surgical specimen with a TBR of 1.5 is correlated to a tumor-positive resection margin. The binary mechanism of ONM-100 allows for a sharp tumor delineation in all patients, giving the surgeon a clinical tool for real-time margin assessment, with a high sensitivity.

Fluorescence-guided imaging for resection margin evaluation in head and neck cancer patients using cetuximab-800CW: A quantitative dose-escalation study.

Tumor-positive resection margins are present in up to 23% of head and neck cancer (HNC) surgeries, as intraoperative techniques for real-time evaluation of the resection margins are lacking. In this study, we investigated the safety and potential clinical value of fluorescence-guided imaging (FGI) for resection margin evaluation in HNC patients. We determined the optimal cetuximab-800CW dose by quantification of intrinsic fluorescence values using multi-diameter single-fiber reflectance, single-fiber fluorescence (MDSFR/SFF) spectroscopy. Methods: Five cohorts of three HNC patients received cetuximab-800CW systemically: three single dose cohorts (10, 25, 50 mg) and two cohorts pre-dosed with 75 mg unlabeled cetuximab (15 or 25 mg). Fluorescence visualization and MDSFR/SFF spectroscopy quantification was performed and were correlated to histopathology. Results: There were no study-related adverse events higher than Common Terminology Criteria for Adverse Events grade-II. Quantification of intrinsic fluorescence values showed a dose-dependent increase in background fluorescence in the single dose cohorts (p<0.001, p<0.001), which remained consistently low in the pre-dosed cohorts (p=0.6808). Resection margin status was evaluated with a sensitivity of 100% (4/4 tumor-positive margins) and specificity of 91% (10/11 tumor-negative margins). Conclusion: A pre-dose of 75 mg unlabeled cetuximab followed by 15 mg cetuximab-800CW was considered the optimal dose based on safety, fluorescence visualization and quantification of intrinsic fluorescence values. We were able to use a lower dose cetuximab-800CW than previously described, while remaining a high sensitivity for tumor detection due to application of equipment optimized for IRDye800CW detection, which was validated by quantification of intrinsic fluorescence values.