Successful treatment of recurrent epithelioid trophoblastic tumor (ETT) with pembrolizumab after pembrolizumab: A case report and review of literature in treatment of ETT.

Background: Epithelioid Trophoblastic Tumors (ETT) are rare, which makes an optimal treatment regimen difficult to determine. Since PD-L1 is expressed in placental tissue and in gestational trophoblastic neoplasia (GTN), immunotherapies such as pembrolizumab have been proposed as possible treatments. Case presentation: The case presented is a 50-year-old postmenopausal female who presented with postmenopausal bleeding and a large, fungating cervical mass. Cervical biopsies confirmed ETT. The patient underwent primary debulking surgery with radical abdominal hysterectomy, bilateral salpingo-oophorectomy, and sigmoid colon resection. The patient was diagnosed with a FIGO Stage IV ETT due to tumor extension to sigmoid colon with a high-risk WHO score of 12. She underwent four cycles of etoposide and cisplatin with etoposide, methotrexate, and dactinomycin (EP-EMA) followed by six months of pembrolizumab maintenance. One year after completion of immunotherapy, the patient was diagnosed with recurrence by vaginal biopsy. PET/CT revealed oligometastatic sites of recurrence, prompting secondary debulking surgery with upper vaginectomy and removal of incisional recurrence. After four cycles of cisplatin/paclitaxel and etoposide/paclitaxel (TP-TE), she received maintenance pembrolizumab for 12 months. Follow-up PET/CT scans revealed no evidence of hypermetabolic activity after 1 year of maintenance therapy. Conclusion: Use of immunotherapy with anti-PD-1 inhibitors has been successful in cases of GTN due to expression of PD-L1 in placental tissue and in GTN. This case adds to the limited data on immunotherapy in advanced ETT and is the first example of using immunotherapy after immunotherapy in the literature.