NPC-1C: A novel, therapeutic antibody to treat pancreas and colorectal cancers.

Abstract

235 Background: NPC-1C (ensituximab) is a chimeric monoclonal antibody being developed as a novel biologic treatment for pancreatic and colorectal cancers. This antibody was selected from a panel of hybridomas generated from mice immunized with semi-purified membrane-associated proteins derived from biologically screened, pooled human allogeneic colon cancer tissues. The NPC-1C epitope appears to be expressed specifically by human colon and pancreatic tumor tissues and cell lines. Methods: Antitumor activity was established in vitro by measuring ADCC with a standard 4-hour 111-Indium release assay on pancreatic and colorectal cancer cell lines. In vivo antitumor efficacy of NPC-1C was tested using pre-established subcutaneous human pancreatic tumor xenograft models. Results: In vitro, the NPC-1C antibody exhibits ADCC activity specifically against human colon and pancreatic tumor cells, but not against control tumor cell lines. The in vivo data showed significant, and reproducible, antitumor action, including some complete tumor regressions. The clinical application for this antibody was bolstered by several examples of human tumor tissues stained with biotin-conjugated NPC-1C that showed a strong correlation of NPC-1C staining against pancreatic and colon tumors. Approximately 45% of tumors stained strongly positive. The staining pattern was typical of elaborated mucin expression, but also showed cytoplasmic and cell membrane staining. Conclusions: A phase I open label, multicenter dose escalation clinical trial with NPC-1C is currently accruing patients with advanced pancreatic and colorectal cancer who are refractory to standard therapy. The primary objectives of the phase I clinical trial are to determine the safety and tolerability of escalating doses of NPC-1C monoclonal antibody therapy and to assess pharmacokinetics and select immune responses to the antibody at each dose level. Secondary objectives are to evaluate evidence of clinical benefit and to explore the immunologic correlates associated with administration of NPC-1C. Results from this trial will determine the minimum standard dosage levels to be used in further trials. [Table: see text]