FUlvestrant in Gynecological Cancers That Are Potentially Hormone Sensitive: the FUCHSia Study

In this phase 2 clinical trial, the aim is to evaluate the efficacy of the ER-antagonist Fulvestrant in women with estrogen receptor positive (ER+) low grade gynecological cancers. The primary objective of the study is to determine the response rate (RR) upon Fulvestrant treatment, comprising either partial or complete response, as determined by RECIST v1.1 criteria for each tumor type. The secondary objectives are to: (1) determine progression-free survival (PFS) upon Fulvestrant treatment, after 3 years, in each tumor type group (2) assess clinical benefit (CB) upon Fulvestrant treatment, comprising complete response, partial response and stable disease, as determined by RECIST v1.1 criteria, in each tumor type group (3) assess duration of response in each tumor type group (4) assess safety and tolerability of Fulvestrant administration in each tumor type group (5) assess quality of life (QoL) and symptoms in each tumor type group. As exploratory objectives, the aim is to: (1) evaluate the feasibility of 16α-18F-fluoro-17β-estradiol (18F-FES) PET imaging for detection of ER expression (2) determine the value of sequential 18F-FES PET scans in predicting response to Fulvestrant (3) collect tumor biopsies and cf-DNA from patients enrolled in the trial. These samples will be subsequently characterized at the genetic level, to identify adaptive response mechanisms to Fulvestrant treatment.