Background: EC145 is a novel folate-receptor targeted agent consisting of a folate molecule linked to a vinca alkaloid. EC20 is a technetium-labeled folate that assesses the presence of folate receptors (FR) in vivo. The objective of this study was to determine the activity of EC145 in patients with chemotherapy refractory lung adenocarcinoma, whose tumors expressed the FR as determined by EC20 imaging.
Methods: Patients with advanced adenocarcinoma of the lung, Eastern Cooperative Oncology Group performance status 0 to 2, normal organ function, those who had progressed after at least two prior cytotoxic regimens, and with EC 20 uptake in at least one index lesion were eligible. The primary objective of the study was the ability to receive four or more cycles of therapy.
Results: Sixty patients were screened and 43 patients were enrolled. Eleven patients (26%) received more than four cycles (95% confidence interval [CI] 14%, 41%), and one patient had partial response (response rate (RR) = 2.3%, 95% CI 0%, 12%). Patients in whom all target tumor lesions expressed FR by EC 20 scans had a trend toward superior results in terms of clinical benefit response (50% versus 14.3 %; p = 0.10) and survival (47.2 weeks versus 14.9 weeks [HR = 0.539, p = 0.101]) compared with those in whom at least one but not all target lesions were positive for FR (FR+).
Conclusion: EC145 demonstrated clinical activity with a good toxicity profile in this population. Uniform uptake of EC20 may predict activity of EC145 and be useful for prospective selection of patients in future trials.