Centrosomal Protein 55 (CEP55) Drives Immune Exclusion and Resistance to Immune Checkpoint Inhibitors in Colorectal Cancer.

Colorectal cancer (CRC) currently ranks as the third most common cancer in the United States, and its incidence is on the rise, especially among younger individuals. Despite the remarkable success of immune checkpoint inhibitors (ICIs) in various cancers, most CRC patients fail to respond due to intrinsic resistance mechanisms. While microsatellite instability-high phenotypes serve as a reliable positive predictive biomarker for ICI treatment, the majority of CRC patients with microsatellite-stable (MSS) tumors remain ineligible for this therapeutic approach. In this study, we investigated the role of centrosomal protein 55 (CEP55) in shaping the tumor immune microenvironment in CRC. CEP55 is overexpressed in multiple cancer types and was shown to promote tumorigenesis by upregulating the PI3K/AKT pathway. Our data revealed that elevated CEP55 expression in CRC was associated with reduced T cell infiltration, contributing to immune exclusion. As CRC tumors progressed, CEP55 expression increased alongside sequential mutations in crucial driver genes (APC, KRAS, TP53, and SMAD4), indicating its involvement in tumor progression. CEP55 knockout significantly impaired tumor growth in vitro and in vivo, suggesting that CEP55 plays a crucial role in tumorigenesis. Furthermore, the CEP55 knockout increased CD8+ T cell infiltration and granzyme B production, indicating improved anti-tumor immunity. Additionally, we observed reduced regulatory T cell infiltration in CEP55 knockout tumors, suggesting diminished immune suppression. Most significantly, CEP55 knockout tumors demonstrated enhanced responsiveness to immune checkpoint inhibition in a clinically relevant orthotopic CRC model. Treatment with anti-PD1 significantly reduced tumor growth in CEP55 knockout tumors compared to control tumors, suggesting that inhibiting CEP55 could improve the efficacy of ICIs. Collectively, our study underscores the crucial role of CEP55 in driving immune exclusion and resistance to ICIs in CRC. Targeting CEP55 emerges as a promising therapeutic strategy to sensitize CRC to immune checkpoint inhibition, thereby improving survival outcomes for CRC patients.

Allogeneic tumor cell-derived extracellular vesicles stimulate CD8 T cell response in colorectal cancer.

Most colorectal cancer (CRC) patients present with a microsatellite-stable phenotype, rendering them resistant to immune checkpoint inhibitors (ICIs). Among the contributors to ICI resistance, tumor-derived extracellular vesicles (TEVs) have emerged as critical players. Previously we demonstrated that autologous transfer of TEVs without miR-424 can induce tumor antigen-specific immune responses in CRC models. Therefore, we postulated that allogeneic TEVs, modified to lack miR-424 and derived from an MC38 cells, could induce CD8+ T cell responses while restraining CT26 cell-based tumor. Here, we show that prophylactic administration of MC38 TEVs, without miR-424, showed a significant augmentation in CD8+ T-cells within CT26 tumors. This allogenic TEV effect was evident in CT26 tumors but not B16-F10 melanoma. Furthermore, we demonstrated the capacity of dendritic cells (DCs) to internalize TEVs, a possible mechanism to elicit immune response. Our investigation of autologously administered DCs, which had been exposed to modified TEVs, underscores their potential to dampen tumor growth while elevating CD8+ T cell levels vis-a-vis MC38 wild-type TEVs exposed to DCs. Notably, the modified TEVs were well tolerated and did not increase peripheral blood cytokine levels. Our findings underscore the potential of modified allogeneic TEVs without immune-suppressive factors to elicit robust T cell responses and limit tumor growth.

Fecal Microbiota Restoration Modulates the Microbiome in Inflammation-Driven Colorectal Cancer.

Chronic inflammation of the colon (colitis) is a known risk factor for inflammatory-driven colorectal cancers (id-CRCs), and intestinal microbiota has been implicated in the etiology of id-CRCs. Manipulation of the microbiome is a clinically viable therapeutic approach to limiting id-CRCs. To understand the microbiome changes that occur over time in id-CRCs, we used a mouse model of id-CRCs with the treatment of azoxymethane (AOM) and dextran sodium sulfate (DSS) and measured the microbiome over time. We included cohorts where the microbiome was restored using cage bedding swapping and where the microbiome was depleted using antibiotics to compare to untreated animals. We identified consistent increases in Akkermansia in mice receiving horizontal microbiome transfer (HMT) via cage bedding swapping, while the control cohort had consistent longitudinal increases in Anaeroplasma and Alistipes. Additionally, fecal lipocalin-2 (Lcn-2), a marker of intestinal inflammation, was elevated in unrestored animals compared to restored and antibiotic-treated counterparts following HMT. These observations suggest a potential role for Akkermansia, Anaeroplasma, and Alistipes in regulating colonic inflammation in id-CRCs.

Allogeneic Tumor Cell-Derived Extracellular Vesicles Stimulate CD8 T Cell Response in Colorectal Cancer.

Colorectal Cancer (CRC) is the second leading cause of cancer-related death in the United States. Most CRC patients present with a microsatellite stable (MSS) phenotype and are highly resistant to immunotherapies. Tumor extracellular vesicles (TEVs), secreted by tumor cells, can contribute to intrinsic resistance to immunotherapy in CRC. We previously showed that autologous TEVs without functional miR-424 induce anti-tumor immune responses. We hypothesized that allogeneic modified CRC-TEVs without miR-424 (mouse homolog miR-322) derived from an MC38 background would effectively stimulate CD8+ T cell response and limit CT26 tumor growth. Here we show that prophylactic administration of MC38 TEVs without functional miR-424 significantly increased CD8+ T cells in CT26 CRC tumors and limited tumor growth, not B16-F10 melanoma tumors. We further show that the depletion of CD4+ and CD8+ T cells abolished the protective effects of MC38 TEVs without functional miR-424. We further show that TEVs can be taken up by DCs in vitro, and subsequent prophylactic administration of autologous DCs exposed to MC38 TEVs without functional miR-424 suppressed tumor growth and increased CD8+ T cells compared to MC38 wild-type TEVs exposed to DCs, in Balb/c mice bearing CT26 tumors. Notably, the modified EVs were well tolerated and did not increase cytokine expression in peripheral blood. These findings suggest that allogeneic-modified CRC-EVs without immune suppressive miR-424 can induce antitumor CD8+ T cell responses and limit tumor growth in vivo.

Tumor models to assess immune response and tumor-microbiome interactions in colorectal cancer.

Despite significant advances over the past 2 decades in preventive screening and therapy aimed at improving patient survival, colorectal cancer (CRC) remains the second most common cause of cancer death in the United States. The average 5-year survival rate of CRC patients with positive regional lymph nodes is only 40%, while less than 5% of patients with distant metastases survive beyond 5 years. There is a critical need to develop novel therapies that can improve overall survival in patients with poor prognoses, particularly since 60% of them are diagnosed at an advanced stage. Pertinently, immune checkpoint blockade therapy has dramatically changed how we treat CRC patients with microsatellite-instable high tumors. Furthermore, accumulating evidence shows that changes in gut microbiota are associated with the regulation of host antitumor immune response and cancer progression. Appropriate animal models are essential to deciphering the complex mechanisms of host antitumor immune response and tumor-gut microbiome metabolic interactions. Here, we discuss various mouse models of colorectal cancer that are developed to address key questions on tumor immune response and tumor-microbiota interactions. These CRC models will also serve as resourceful tools for effective preclinical studies.

Clearance of solvents and small molecule impurities in antibody drug conjugates via ultrafiltration and diafiltration operation.

Ultrafiltration and diafiltration (UF/DF) processes by tangential flow filtration (TFF) are frequently used for removal of solvents and small molecule impurities and for buffer exchange for biopharmaceutical products. Antibody-drug conjugates (ADCs) as an important class of biological therapeutics, carry unique solvents and small molecule impurities into the final UF/DF step as compared to standard antibody preparation. The production process of ADCs involves multiple chemical steps, for example, reduction and conjugation. The clearance of these solvents and small molecules by UF/DF, specifically the DF step, has been assessed and described herein. The rates of clearance for all the impurities in this study are close to the ideal clearance with no apparent interaction with either the protein or the TFF membrane and system. The effect of process variables during DF, such as pH, temperature, membrane loading, transmembrane pressure, and cross flow rate, has also been evaluated and found to have minimal impact on the clearance rate. These results demonstrate efficient clearance of solvents and small molecule impurities related to the ADC process by the DF process and provide a general data package to facilitate risk assessments based on the sieving factors and program specific needs.