PI is leaving the University.

The purpose of this study is to see if Dostarlimab is an effective treatment for Gestational Trophoblastic Neoplasia (GTN).

Inclusion Criteria:

1. Patients with persistent unresectable Gestational Trophoblastic Neoplasia (GTN) disease
2. Female patients >18 years old.
3. Pretreatment archival tissue (if available) must be submitted for correlative studies. If pre-treatment tissue is not available, this does not exclude the patient.
4. Patients must have recovered from the effects of recent surgery or radiotherapy (persistent toxicity, CTCAE grade ≤1 except for alopecia, sensory neuropathy, or fatigue).

Exclusion Criteria:

1. Prior therapy with anti-Programed Death (PD)1/Programed Death Ligand-1 (PD-L1) or anti-CTLA4 antibody
2. Participant must not be simultaneously enrolled in any interventional clinical trial.
3. Participant must not have had major surgery ≤3 weeks prior to initiating protocol therapy and participant must have recovered from any surgical effects.
4. Participant must not have received investigational therapy ≤ 4 weeks, or within a time interval less than at least 5 half-lives of the investigational agent, whichever is shorter, prior initiating protocol therapy.