This study aimed to investigate the potential molecular mechanism of SPDEF in immune evasion of colorectal cancer (CRC) and examine its impact on macrophage M2 polarization using the TCGA and GEO databases. By combining TCGA and GEO databases, differential gene expression between CRC samples and standard tissue samples was analyzed to screen for immune-related genes (IRGs) associated with the prognosis of CRC patients. A predictive risk model was constructed based on 18 key IRGs, which were then validated using the GEO dataset. The relationship between transcription factors and IRGs was further explored to investigate their regulatory network in CRC. In vivo and in vitro experiments were carried out to validate these regulatory relationships and explore the function of SPDEF and CCL28 in CRC. Twelve key IRGs associated with clinical and pathological characteristics of CRC patients were identified. Among them, CCL28 significantly impacted macrophage infiltration in CRC cells and may be a critical factor in immune evasion. In both in vitro and in vivo experiments, overexpression of SPDEF upregulated CCL28 expression, thereby suppressing M2 polarization of macrophages and inhibiting CRC cell proliferation and tumor growth. Notably, interference with CCL28 could reverse the effect of SPDEF overexpression. SPDEF can suppress immune evasion of CRC cells by activating CCL28, which is achieved through the modulation of M2 polarization of macrophages. This provides a new research direction and potential therapeutic target for immunotherapy in CRC.

The tumor vascular barrier restricts the penetration of antibody‐conjugated nanomedicine, severely limiting its therapeutic efficacy. Selective delivery of nitric oxide (NO) to tumors can modulate vascular permeability, thereby enhancing the penetration of antibody‐conjugated nanomedicine. Herein, we developed an ultrasound‐responsive NO‐releasing material, named HA‐SNO, based on a hyaluronic acid backbone, which releases NO upon exposure to ultrasound waves. After systemic administration of HA‐SNO, tumor‐localized release of NO was achieved using a focused ultrasound system operating at a low intensity (1 MHz, 2.0 W/cm ² , 50% duty cycle). The released NO induced vasodilation and disrupted the tumor vascular barrier, thereby promoting extravasation and more homogeneous intratumoral distribution of HER2‐targeted antibody–conjugated nanomedicine (HER2–SN38). This strategy exhibited significantly enhanced anti‐tumor efficacy, with a tumor inhibition rate of 97.67%. These findings highlight the potential clinical utility of ultrasound‐triggered tumor‐selective delivery of NO in overcoming vascular barriers to drug delivery.

Dual Opdivo plus Yervoy immunotherapy, targeting the immune checkpoints PD1 and CTLA‐4, is successful in clinical use. However, it is associated with a high incidence of adverse events, and its therapeutic efficacy needs improving. In this study, polymeric multivalent Fc‐binding peptides (PLG‐Fc‐III‐4C) are employed to fabricate a bispecific antibody (PD1/CTLA‐4 BsAb) to potentiate dual immunotherapy targeting PD1 and CTLA‐4. The PD1/CTLA‐4 BsAb is prepared by mixing PLG‐Fc‐III‐4C with aPD1 and aCTLA‐4 in an aqueous solution for 3 h using the clinically optimal 3:1 proportion of aPD1 to aCTLA‐4. PD1/CTLA‐4 BsAb significantly inhibits tumors in MC38 colon cancer‐bearing mice more effectively than the combination of aPD1 and aCTLA‐4, with tumor suppression rates of 96.8% and 77.3%, respectively. It also induces a higher percentage of CD8⁺ T cells and increases the secretion of effector cytokines while reducing Treg levels in tumors compared to phosphate‐buffered saline, indicating significant tumor immunity regulation. Mechanistically, a 6.3‐fold increase in PD1/CTLA‐4 BsAb accumulation in tumors due to the tumor targeting ability of aPD1, and the PD1/CTLA‐4 BsAb significantly reduces the adverse colitis event in healthy mice, compared to aPD1 and aCTLA‐4. Thus, these findings provide a novel approach to enhance antitumor therapy using aPD1 and aCTLA‐4.