[3] It is being developed with a companion imaging agent, etarfolatide, that identifies patients that express the folate receptor and thus would likely respond to the treatment with vintafolide.

[1] Endocyte remains responsible for the development and commercialization of etarfolatide, a non-invasive companion imaging agent used to identify patients expressing the folate receptor that will likely respond to treatment with vintafolide.

[5] In 2014 Merck and Endocyte stopped a late-stage study (PROCEED) of vintafolide in treating ovarian cancer on the recommendation of a data safety monitoring board, saying that the drug failed to improve progression-free survival.

Elevated expression of the folate receptor occurs in many diseases, including other aggressively growing cancers and inflammatory disorders.

[9] Vintafolide binds to the folate receptor and is subsequently taken up by the cell through a natural internalization process called endocytosis.