Abstract Apoptosis or programmed cell death is essential for the normal functioning and survival of most multi-cellular organisms. The morphological and biochemical characteristics of apoptosis are highly conserved during the evolution. Therapeutic strategies based on exogenous delivery of the native form of superoxide dismutase (SOD), a free radical scavenger, are limited because of its short half-life (approximately 6 min) in vivo and poor permeability across the blood barrier and cell membrane. In this study, the spectrum of in vivo anti cancer activity of a Streptomyces SOD with a carrier protein designated Kavir-48by apoptotic function was assessed. Two xenograft models including LXFl 529 and LXFL H460 lung cancer cells were used. Purified protein complex was administrated through intra- peritoneal injection (ip) for 4 weeks. The results showed that treatment with 300 mg/kg of kavir-48 significantly reduced the growth of xenografted tumor with a tumor growth inhibition (TGI) of 70 % for LXFI 529 cell line. In addition, no adverse effects were observed based on general appearance, weight loss or reduction in weight gain. Finally, Kavir-48, demonstrated a highly anti-tumor efficacy in vivo and a tolerability profile amenable to intra peritoneal administration. It acts as a promising therapeutic target against cancer.Further analysis on this antitumor metabolite on gene expression profiles involved in regulation of apoptosis and oxidative stress pathways in different cancer cells in progress. Note: This abstract was not presented at the meeting. Citation Format: Nasrin Moazami, Fatoulah Hakami, Hamideh Ofoghi, Massoud Ghaffarpour. A novel metabolite from an extremophile Streptomyces with apoptosis regulator function. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5105. doi:10.1158/1538-7445.AM2014-5105