Abstract 4993: CJRB-101 induces immune responses through the GUT-TME axis in immune cell-driven mechanism in lung cancer models

Abstract Background Live biotherapeutic products (LBPs) are known to enhance immune responses through the GUT-TME axis. Here, we investigate the GUT-TME-related immune cell profiling and signals associated with the anti-cancer effects of CJRB-101. Methods Tumors from NSCLC patients (anti-PD-1 refractory) were transplanted in Hu-CD34-NSG to establish humanized patient-derived xenograft (PDX) models. CJRB-101 was administered at 1x109 CFU (p. o. , BID) or combination with anti-PD-1 (10 mpk, i. p. , BIW). TME was analyzed using multiplex IHC, flow cytometry and scRNA sequencing. Samples were collected from C3PQ syngeneic mice at multiple timepoints for GUT-TME immune cell profiling. For depletion assay, immune cells were individually depleted during the combination treatment. TLR4-mediated mechanism was evaluated using ex vivo and in vivo assay treated with CJRB-101 or cell membrane of CJRB-101. Results CJRB-101 combined with pembrolizumab effectively suppressed tumor growth in anti-PD-1 resistant PDX models. Further analysis revealed a correlation between the activity of NK cells and angiogenesis inhibition. Abundance of NK/NKT was higher in the CJRB-101 treated group compared to the vehicle group in multiple PDX models. The expression of GZMB and IFNG in NK/NKT cells was significantly higher in the CJRB-101 treated group compared to the vehicle group in YHIM2014 (p0. 001). CJRB-101 treated group showed significantly higher expression of antiangiogenic IL1B (p0. 001) while the expression of pro-angiogenic VEGFA (p=0. 002) was lower compared to the vehicle group in YHIM2014 cancer cells. Macrophages in the intestine were increased at Day 3 in the CJRB-101 group compared to anti-PD1, while NK cells, granulocytes, CD3+, CD4+, CD8+ T cells increased at Day 10 in the syngeneic model. Depletion assay confirmed that macrophages, CD8+ T cells and neutrophils were pivotal in the anti-cancer effects of CJRB-101. We observed that TAK242 and MD2 reduced the IL-6 secretion of Raw264. 7 in a dose-dependent manner. The cell membrane played a key role in increasing BMDM M1 polarization and repolarization of M2 to M1, and that inhibition of TLR4 resulted in a decrease in BMDM repolarization. TLR inhibition also demonstrated that TGI decreased from 34% to 20% when treated with cell membrane + TAK242 compared to cell membrane monotherapy. Conclusions This study showed that macrophages were the dominant immune population in the early stages then T cells (CD3, CD4, CD8), NK cells and granulocytes became more active in the latter stages of the GUT-TME-axis immune response. In vivo results indicated that anti-cancer efficacy of CJRB-101 is immune-cell driven by TLR4-dependent stimulation of key immune cell populations (macrophages, CD8+ T cells, neutrophils) modulated by the cell membrane of CJRB-101. CJRB-101 is currently undergoing clinical investigation for treatment of patients with advanced NSCLC. Citation Format: Arim Min, Bo-eun Kwon, Seong-san Kang, Sujeong Baek, Junwon Yang, Hyunkyung Park, Jieun Im, Hyunjeong Kim, Jaemin Kim, Jieun Kwon, Dong Kwon Kim, Jii Bum Lee, Hyeonseok Oh, Seung Min Yang, Yu Jin Han, Mi hyun Kim, Heekyung Han, Kwangmin Na, Young Taek Kim, Mi Ran Yun, Jae Hwan Kim, Youngseon Byeon, Young Seob Kim, Min Hee Hong, Sun Min Lim, Kyoung-Ho Pyo, Byoung Chul Cho. CJRB-101 induces immune responses through the GUT-TME axis in immune cell-driven mechanism in lung cancer models abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 4993.