Phase II study of ADI-PEG 20 in patients with relapsed sensitive or refractory small cell lung cancer.

Abstract

e17558 Background: Small cell lung cancer (SCLC) is a rapidly progressing malignancy. The majority of patients show relapse after initial therapy. Second-line chemotherapy has limited activity, and alternative therapies are desperately needed. ADI-PEG 20 is pegylated recombinant arginine deiminase which degrades arginine, resulting in growth inhibition of SCLC tumor cells deficient in argininosuccinate synthetase (ASS) in xenografts and in vitro, and induction of sensitivity to cell autophagy. Based on ASS deficiency identified in ~50% of human SCLC, a phase II trial in patients with relapsed SCLC was initiated. Methods: This is an open label, multicenter, phase II study of ADI-PEG 20 in subjects with relapsed SCLC. The primary objective is to determine overall response rate according to RECIST. Secondary objectives are to measure safety, overall survival, pharmacodynamics, and immunogenicity. Patients with histologically documented SCLC, measurable disease, and ASS negative (by immunohistochemistry) or weakly positive (< 5%) tumor are eligible. Patients with severe comorbidities, metastatic disease of the central nervous system, prior treatment with 3 or more lines of chemotherapy, and known allergy to pegylated products are excluded. Patients are enrolled in either Cohort 1 (Sensitive disease—response to first-line therapy maintained ≥ 90 days) or Cohort 2 (Refractory disease—no response to first-line therapy or progression within 90 days, or progression after 2 lines of therapy). All patients receive weekly intramuscular injections of ADI-PEG 20 at a dose of 320 IU/m2 (36.8 mg/m2) until disease progression. The two cohorts will be analyzed separately with a two-stage design. For Cohort 1, if 3/15 patients respond, additional 13 patients will be accrued to the second stage. For Cohort 2, if 1/9 patients responds, additional 8 patients will be accrued to the second stage. Results: Cohort 1 has enrolled 2 of planned 15 patients and Cohort 2 has enrolled 7 of 9 planned patients. Conclusions: Will be published when study is complete.