Use of a PD-1 checkpoint inhibitor in a patient with ultra-high-risk gestational trophoblastic neoplasia and gastrointestinal metastases

• GTN are rare diseases that are typically chemotherapy-responsive. • Gastrointestinal metastases from GTN are extremely rare and indicate a poor prognosis. • The use of PD-1/PD-L1 checkpoint inhibitors in low-risk GTN is not well-established. • This case supports continued investigation of PD-1/PD-L1 inhibitor use as a part of first-line treatment for high risk GTN. Gestational trophoblastic neoplasia (GTN) are rare diseases that are typically chemo-responsive. While the majority of patients are cured with chemotherapy alone, a small portion of cases are fatal due to chemotherapy resistance. Risk factors for treatment failure are liver and brain metastases, extensive disease, and chemo-refractory disease. Gastrointestinal (GI) metastases are extremely rare and indicate a poor prognosis. Treatment with immunotherapy has been studied and included in treatment guidelines for high-risk and chemotherapy-resistant GTN. This case reports on the early use of programmed cell death protein 1 (PD-1) inhibitor in combination with systemic chemotherapy in a patient with ultra-high risk GTN with GI metastases.