Small cell lung cancer (SCLC) is a highly aggressive neuroendocrine tumor with a poor prognosis and limited therapeutic options. Most patients present with extensive stage disease, where recent advances in immunotherapies, including bi-specific T cell engager (BiTE®) antibody constructs, represent a promising new therapeutic approach. BiTE® molecules have demonstrated durable complete responses in the clinic in hematological malignancies. Similar to hematological malignancies, SCLC is also a widely-disseminated malignancy that shows very high response rate to first line therapies with high rates of disease recurrence, features which may support efficacy of the BiTE® modality. Next generation sequencing (NGS) identified Delta-like Ligand 3 (DLL3) as a highly specific tumor associated antigen for SCLC, with consistent expression in tumors and very low expression in normal tissues. Tumor expression of DLL3 protein was confirmed by IHC, with 30 of 35 SCLC tumors staining positive for DLL3. DLL3 BiTE® antibody constructs showed low pM potency in vitro and also demonstrated significant inhibition of tumor growth in vivo in an orthotopic model of SCLC. A half-life extended (HLE) BiTE® targeting DLL3 demonstrated antibody-like pharmacokinetic properties in single-dose studies in non-human primates (NHP), with a half-life of 11 days. This is predicted to support every other week dosing in humans. The combination of high potency and excellent PK properties suggests that HLE BiTE® molecules may provide a useful tool for targeting residual disease in SCLC patients whose tumors express DLL3.

Citation Format: Michael J. Giffin, Ed K. Lobenhofer, Keegan Cooke, Tobias Raum, Jennitte Stevens, Pedro J. Beltran, Angela Coxon, Paul E. Hughes. BiTE® antibody constructs for the treatment of SCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3632. doi:10.1158/1538-7445.AM2017-3632