Targeting HER2/neu Oncogene Overexpression With Ado-Trastuzumab Emtansine in the Treatment of Metastatic Salivary Gland Neoplasms: A Single-Institution Experience

Salivary gland cancers in elderly patients: challenges and therapeutic strategies

Salivary gland carcinomas (SGCs) are the most heterogeneous subgroup of head and neck malignant tumors, accounting for more than 20 subtypes. The median age of SGC diagnosis is expected to rise in the following decades, leading to crucial clinical challenges in geriatric oncology. Elderly patients, in comparison with patients aged below 65 years, are generally considered less amenable to receiving state-of-the-art curative treatments for localized disease, such as surgery and radiation/particle therapy. In the advanced setting, chemotherapy regimens are often dampened by the consideration of cardiovascular and renal comorbidities. Nevertheless, the elderly population encompasses a broad spectrum of functionalities. In the last decades, some screening tools (e.g. the G8 questionnaire) have been developed to identify those subjects who should receive a multidimensional geriatric assessment, to answer the question about the feasibility of complex treatments. In the present article, we discuss the most frequent SGC histologies diagnosed in the elderly population and the relative 5-years survival outcomes based on the most recent data from the Surveillance, Epidemiology, and End Results (SEER) Program. Moreover, we review the therapeutic strategies currently available for locoregionally advanced and metastatic disease, taking into account the recent advances in precision oncology. The synergy between the Multidisciplinary Tumor Board and the Geriatrician aims to shape the most appropriate treatment pathway for each elderly patient, focusing on global functionality instead of the sole chronological age.

ERBB2 amplification status in 67 salivary duct carcinomas assessed by immunohistochemistry, fluorescence in situ hybridization, and targeted exome sequencing

Salivary duct carcinoma (SDC) is an aggressive salivary gland malignancy with poor survival. Approximately 30% SDC harbor HER2 amplification and response to trastuzumab has been reported. However, a systematic approach for HER2 status assessment in this tumor type has not been established. A total of 67 tumor samples were evaluated for HER2 protein overexpression or ERBB2 gene amplification using at least 2 methods: immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and/or targeted exome next-generation sequencing (NGS). NGS assessed ERBB2 copy number fold change (FC) and total copy number (TCN). HER2 status was first determined by IHC/FISH according to the 2018 ASCO/CAP breast cancer guidelines. FISH results, the "gold standard", were compared with the NGS results. All (15/15) IHC positive, 35% (6/17) equivocal, and no (0/19) IHC negative SDC were HER2 amplified by FISH. HER2 FISH signal/cell showed a good correlation with FC (Spearman correlation: 0.708, R²: 0.501, p < 0.0001) and TCN (Spearman correlation: 0.763, R²: 0.582, p < 0.0001). Receiver operating characteristics curve estimation showed an area under curve (AUC) of 0.975 for ERBB2 FC. FC cutoff of ≥1.8 corresponded to an accuracy of 95.2% for ERBB2 amplification (Youden's index: 0.84, sensitivity: 89.47%, specificity: 100%). FC < 1.3 could be reliably classified as ERBB2 not amplified and FC ≥ 1.3 and <1.8 as equivocal. TCN estimation showed AUC of 0.981. TCN cutoff of >6.0 corresponded to an accuracy of 92% for HER2 amplification (Youden's index: 0.81, sensitivity: 81.2%, specificity: 100%). TCN < 4 could be reliably classified as ERBB2 not amplified and TCN ≥ 4.0 and ≤6.0 as equivocal. FC and TCN were binarized with respective cutoffs of ≥1.8 and ≥6.0 and the proportion of agreement with FISH were 95% and 92%, respectively. The assessment of ERBB2 copy number by NGS is accurate and reliable with FC or TCN nearly equivalent to FISH in identifying HER2 amplified SDC.

Case series of docetaxel, trastuzumab, and pertuzumab (DTP) as first line anti-HER2 therapy and ado-trastuzumab emtansine (T-DM1) as second line for recurrent or metastatic HER2-positive salivary duct carcinoma

OBJECTIVE

Salivary duct carcinoma (SDC) overexpresses Human Epidermal growth factor Receptor 2 (HER2) in 29-46% of cases, favoring anti-HER2 therapy. Here, we present the results of patients with recurrent or metastatic HER2-positive SDC treated with docetaxel, trastuzumab, and pertuzumab (DTP) as first line anti-HER2 therapy and subsequently ado-trastuzumab emtansine (T-DM1) in second line. Furthermore, we searched for potential biomarkers.

METHODS

Retrospective case series from a tertiary hospital. First line anti-HER2 treatment consisted of DTP, after progression T-DM1 was considered for patients with an adequate performance status. Objective response rate (ORR), progression-free survival (PFS) and overall survival (OS) were assessed and related to mRNA-based PI3K and MAPK signaling pathway activity scores.

RESULTS

Thirteen SDC HER2 + patients received DTP. In twelve evaluable patients, one complete response (CR) and six partial responses (PR) were observed (ORR 58%), with a median PFS of 6.9 months (95%-CI 5.3-8.5). Seven patients received subsequent T-DM1 in second line, resulting in four PR (ORR 57%), with a median PFS of 4.4 months (95%-CI 0-18.8). Median OS after start of DTP was 42.0 months (95%-CI 13.8-70.1). Grade ≥ 3 toxicity on DTP was seen in 39% of patients, and 14% on T-DM1. Highest combined PI3K and MAPK signaling was seen in the patient with CR and lowest in the patient with progressive disease on DTP.

CONCLUSION

In R/M HER2-positive SDC patients DTP followed by T-DM1 upon progression are promising treatments, leading to responses in the majority (58%) of the patients at an acceptable toxicity profile.

Combination Chemohormonal Therapy in Metastatic Salivary Duct Carcinoma

Patient: Male, 68-year-old

Final Diagnosis: Salivary duct carcinoma

Symptoms: Bone pain • dyspnea

Medication:—

Clinical Procedure: Chemotherapy

Specialty: Oncology