This trial is testing the drug MK-2870 in people with endometrial cancer that has already been treated with certain types of drugs. This trial will compare MK-2870 to 2 standard chemotherapies used to treat endometrial cancer: doxorubicin and paclitaxel. 

The purpose of this trial is to test the safety MK-2780, see how well it works compared to the 2 standard chemotherapies, see if participants who get MK-2870 live longer compared to those who get a standard chemotherapy, and see if participants who get MK-2870 have a better quality of life compared to those who get who get a standard chemotherapy.
   
MK-2870 is experimental, which means it has not been approved by any national authority such as the U.S. Food and Drug Administration (FDA). Doxorubicin and paclitaxel are approved by the FDA.

Participants will be randomized into one of two groups. Randomization is like flipping a coin and there is a 50/50 chance of being assigned to either group. Group one will get MK-2870 and group 2 will get doxorubicin or paclitaxel. All treatments are given via an intravenous (IV) infusion.

Both groups will need to come in for trial visits. The frequency of visits depends on which group the participant is assigned to and if in group 2, which drug they are assigned to.

Total study participation is expected to last approximately 4 years.