A phase I study of EP-100, a luteinizing hormone releasing hormone (LHRH) ligand conjugated to a synthetic cytolytic peptide in patients with advanced refractory LHRH- receptor (R)-expressing tumors.

3060 Background: EP-100 is a synthetic 28 amino acid LHRH peptide conjugated to an 18 aa cytolytic peptide. Selective targeting in LHRH-R expressing cells occurs via direct binding to the extracellular membrane receptor followed by disruption of the membrane by the cytolytic peptide portion. A first in human, phase I study was performed. Methods: Eligible pts had adequate organ function and LHRH-R tumor expression, as determined by IHC. EP-100 was given IV (30-60 min) weekly x 3 for cohorts 1- 6 (n=20 at 0.6 - 5.2 mg/m2) and then twice weekly x 3 for cohorts 7- 11 (n=18 at 7.8 - 40 mg/m2) with a week break. The pharmacokinetic profile of EP-100 and antibody production against EP-100 was determined by a validated HPLC/MS and ELISA respectively. Potential activity of EP-100 on the pituitary gonadotropes was determined by plasma LH and FSH. Results: We screened 97 pts, archival tumor tissue obtained from 81 pts; 53 (65%) were positive for LHRH-R, of which 37 were enrolled (female 76%) and treated. The LHRH-R...