A phase I study of folate immune therapy (EC90 vaccine administered with GPI-0100 adjuvant followed by EC17) in patients with renal cell carcinoma.

This is the first phase I, open-label study to assess the safety, pharmacokinetics, and antitumor activity of a novel immunotherapeutic regimen known as Folate Immune (EC90 vaccine administered with GPI-0100 adjuvant followed by EC17, a folate-targeted hapten immunotherapy that targets folate receptor expressing cancer cells), which is designed to convert poorly immunogenic tumors to highly immunogenic tumors in patients with metastatic renal cell carcinoma. Three to 6 patients were enrolled in each cohort. In the vaccination phase, patients were given once weekly vaccinations of 0.2 mg of EC90 plus 3.0 mg of GPI-0100 for 3-5 weeks. In the treatment phase, patients were treated with 0.031, 0.092, or 0.276 mg/kg of EC17, 5 d/wk, for weeks 3, 4, or 6. Forty-one patients were enrolled in the study of which 33 patients received ≥1 treatment of EC17. Two dose-limiting toxicities were observed including grade 4 anaphylaxis and grade 3 pancreatitis. During the vaccination phase, mild to moderate injection site reactions were the most frequently reported adverse events. During the treatment phase, transient hypersensitivity reactions were the most common adverse event. Partial response was noted in 4% (1/28) of patients, and stable disease was noted in 54% (15/28) of patients after cycle 1 and was maintained in the majority of patients entering the extension phase of the study. EC90 vaccine with GPI-0100 adjuvant followed by EC17 is safe and well tolerated. The recommended regimen for further studies is 4 weekly vaccinations with 0.2 mg of EC90 plus 3.0 mg GPI-0100 followed by treatment with 0.3 mg of EC17.