Abstract 6433: A novel bacterial strain, CJRB-101, induces anti-cancer effects by repolarization of M2 to CXCL9 and CXCL10 dual expressing M1 macrophages in humanized non-small cell lung cancer mice models

Abstract

Abstract Backgrounds: Live biotherapeutic products (LBPs) emerged as potential therapeutics to overcome the limitation of ICIs. This research shows that CJRB-101, a novel bacterial strain, can improve anti-tumor effects in synergy with pembrolizumab in non-small cell lung cancer (NSCLC). Objectives and Methods: Tumors from NSCLC patients (anti-PD-1 refractory and resistant) were transplanted into Hu-CD34-NSG to establish humanized patient-derived xenograft (PDX) mice models. Five models (YHIM-2003, 2004, 2009, 2010 and 2014) were treated with CJRB-101 at low (5 × 107 CFU) or high (109 CFU) doses, or with pembrolizumab (10 mg/kg, i.p., Q5D) or in combination. Tumor growth inhibition (TGI) rate was measured. Tumor microenvironment (TME) was analyzed using multiplex IHC, flow cytometry and single cell RNA sequencing. Ex-vivo assays were performed to validate in silico findings. Results: Tumor in PDX models was unresponsive to pembrolizumab alone, however, in combination with CJRB-101 effectively suppressed tumor growth. The synergy was highlighted in YHIM-2009 where TGI was 10-fold higher (56%) than pembrolizumab group (5%). Immune profiling revealed that macrophages may be responsible for the anti-tumor effects of CJRB-101. IHC showed significantly increased antigen presenting specialized DCs (CD16+CD68−CD11c+) and granzyme B+ CD8+ T cells in the tumor by CJRB-101 compared to pembrolizumab (p<0.01). This suggested that CJRB-101 induced infiltration of cytotoxic CD8 T cells into the tumor nest by enhancing antigen presenting machinery. Trajectory analysis showed that CJRB-101 induced repolarization of M2 to M1 macrophages, characterized by high expression of CXCL9/10. CXCL9+/10+ M1 macrophages were comparatively more abundant in the combination group (23.11%) than the pembrolizumab group (0.91%). CXCL9/CXCL10 expression in macrophages was higher in the CJRB-101 group compared to the pembrolizumab group (p<0.0001). The combination group (10.84%) had a higher relative abundance of CD8+ T cells compared to the pembrolizumab group (1.58%) and higher IFNγ expression in CD8+ T cells compared to the pembrolizumab group (p=0.0152), suggesting that CJRB-101 repolarized macrophages and recruited active CD8+ T cells. Co-culture assays using bone marrow-derived macrophages validated that CJRB-101 drove differentiation towards F4/80+ or MHC II+ expressing M1 macrophage (p<0.0001) and repolarized existing M2 (CD206+) to M1 (p=0.0002). Conclusion: Combination treatment of CJRB-101 with anti-PD-1 showed synergistic anti-tumor effects via repolarization of M2 to M1 macrophages, leading to activation of CD8+ T cells in TME. Especially, CXCL9+/10+ M1 macrophage playing a key role in TGI induced by CJRB-101 in NSCLC models. Findings from this study provided rationale for clinical investigation of CJRB-101. Citation Format: Arim Min, Chun-bong Synn, Seong-san Kang, Bo-eun Kwon, Junwon Yang, Hyunkyung Park, Jieun Im, Hyunjeong Kim, Sujeong Beak, Dong Kwon Kim, Jii Bum Lee, Hyeonseok Oh, Seung Min Yang, Yu Jin Han, Mi hyun Kim, Heekyung Han, Kwangmin Na, Young Taek Kim, Sungwoo Lee, Mi Ran Yun, Jae Hwan Kim, Youngseon Byeon, Young Seob Kim, Ji Yun Lee, Chang Gon Kim, Min Hee Hong, Sun Min Lim, Kyoung-Ho Pyo, Byoung Chul Cho. A novel bacterial strain, CJRB-101, induces anti-cancer effects by repolarization of M2 to CXCL9 and CXCL10 dual expressing M1 macrophages in humanized non-small cell lung cancer mice models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6433.