Diagnostic and Therapeutic Approach in a Metastatic Vaginal Adenocarcinoma: A Case Report

Abstract

Background: Vaginal adenocarcinomas (VAC) are most often reported after intrauterine exposition to diethylstilbestrol (DES). Rarely, VACs are reported as a malignant transformation of vaginal adenosis or endometriosis, in the context of chromosomal abnormalities or malformations of the uterus or the vagina. VACs without DES exposition have a poor prognosis and a significantly worse outcome compared to vaginal squamous cell carcinomas or DES-associated VACs.

Objective: Here, we report the case of a primarily metastatic VAC, treated successfully with different lines of chemo-, antiangiogenic, antibody, and immunotherapy.

Case: The 49-year-old patient presented in 5/2018 with a primarily pulmonary metastatic VAC. Significant tumor reduction was seen after six cycles of carboplatin AUC5/paclitaxel 175 mg/m²/bevacizumab 15 mg/kg q3w. Bevacizumab maintenance therapy and later cisplatin mono 50 mg/m² q2w led to local and distant tumor progression. To identify a potential targeted therapy, new tumor biopsies were obtained. Immunohistochemistry revealed ERBB2 expression, and paclitaxel 80 mg/m² weekly plus trastuzumab 4 mg/m² respectively 2 mg/m² q3w was administered. Due to local and pulmonal tumor progression after 6 months and persistent ERBB2 positivity, the therapy was adjusted to trastuzumab emtansine (T-DM1) 3.6 mg/kg q3w; however, the patient remained locally progressive after three cycles of T-DM1 and additionally showed a new bone metastasis. The new tumor biopsies revealed a combined positive score (CPS) of 2 regarding PD-L1, and pembrolizumab 200 mg q3w was initiated. The bone metastasis was radiated and treated with denosumab 120 mg q4w. Extreme tumor regression followed by stable disease was maintained for 9 months. Due to a slow locoregional progress only with new inguinal lymph node and pararectal lymph node metastases, a new tumor biopsy was taken. Molecular profiling showed an ARID1A mutation, a mutational burden of 5.1 mutations per megabase, and no genfusions. Based on these findings, therapy with PD-L1 antibodies, PD-1 antibodies, gemcitabine, or dasatinib was suggested. Therefore, administration of pembrolizumab was continued and local radiation therapy was performed. This led to a decrease in local tumor manifestations and a stable systemic disease.

Conclusion: Our case demonstrates the diagnostic and therapeutic approach in a patient with primary metastatic vaginal adenocarcinoma. By tumorgenetic profiling, different lines of systemic therapy, namely, antiangiogenic therapy, monoclonal antibody therapy, immunotherapy, and local radiation therapy, were identified and successfully administered.

Keywords: abscopal effect; immune checkpoint blockade; mutational burden; trastuzumab; vaginal adenocarcinoma.