A FAP-targeting minibody-IRDye700DX for photodynamic therapy of the cancer associated fibroblast

The cancer associated fibroblast (CAF) orchestrates an aberrant tumor microenvironment in pancreatic ductal adenocarcinoma (PDAC), contributing to poor patient survival. Fibroblast activation protein (FAP)-targeted depletion of the CAF in PDAC could modulate the tumor microenvironment and make it more susceptible to immune response or systemic therapies. Here, we developed a FAP-targeting minibody conjugated to the photosensitizer IRDye700DX for ablation of the CAF with photodynamic therapy. We characterized efficiency of the minibody-IRDye700X in vitro and in vivo in a murine subcutaneous PDAC model.The minibody was equipped with the chelator diethylenetriaminepentaacetic acid (DTPA) and the photosensitizer IRDye700DX (DTPA-700DX-MB). Absorbance and emission spectra and production of singlet oxygen upon exposure to 690 nm light where determined. Binding to murine PDAC cell line PDAC299, murine fibroblast cell line 3T3 and its FAP-transfected counterpart 3T3-FAP were determined, as well as cell viability upon exposure to varying doses of 690 nm light. Biodistribution of 111In-labeled DTPA-700DX-MB was assessed in C57BL/6 mice carrying subcutaneous PDAC299 tumors at 4, 24 and 48 hours post injection (n=5). Specificity was confirmed by co-injection of a molar excess unlabelled minibody, and uptake in the tumor was visualized with in vivo fluorescence imaging (IVIS Lumina II). Therapeutic efficacy was determined in mice carrying PDAC299 tumors on both flanks. 24 hours after injection of DTPA-700DX-MB (n=3) or PBS (n=3), one of the tumors was exposed to 100 J/cm2 230 mW/cm2 690 nm light. Induction of apoptosis was investigated with cleaved-caspase-3 immunohistochemistry and quantified by automated analyses.Spectral properties of IRDye700DX were retained upon conjugation (Absmax = 690 nm, Emmax = 700 nm), and DTPA-700DX-MB induced formation of singlet oxygen upon illumination. Binding affinity to 3T3-FAP cells was good (IC50 = 44 nM), with efficient internalization (16.2 ± 0.98% of added activity). Protein concentration dependent cytotoxicity was observed upon illumination with 30-60 J/cm2 690 nm light. Lack of binding to or cytotoxicity of naive 3T3 cells and PDAC299 tumor cells indicated FAP-specificity. In vivo, maximal relative tumor uptake of 7.3 ± 1.02 %ID/g and a tumor-to-blood ratio of 8.3 ± 0.82 were found at 24 hours post injection. Significantly lower uptake was found upon co-injection of an excess unlabelled minibody in the tumor (4.4 ± 1.45 %IA/g, p = 0.0059) and in the tibia with bone marrow (9.85 ± 1.09 vs 3.64 ± 0.80 %IA/g, p < 0.0001), but not in other examined organs. Uptake in the tumor could be visualized with fluorescence imaging. In the in vivo therapy experiment, upregulation of cleaved caspase-3 was found in illuminated tumors of both PBS and minibody-injected groups, with significantly higher upregulation in the minibody group (p = 0.0432).DTPA-700DX-MB binds to FAP-expressing cells and targets PDAC299 tumors in mice. The conjugate induces apoptosis upon illumination with 690 nm light, indicating feasibility of FAP-targeted photodynamic therapy. In ongoing experiments, specificity of cell death in vivo, targeting to orthotopic PDAC299 tumors and the effect of FAP-targeted depletion on the tumor microenvironment are investigated.     

Association of KMT2C/D loss-of-function variants with response to immune checkpoint blockades in colorectal cancer

Immune checkpoint inhibitors (ICIs) have become important treatment strategies, yet responses vary among patients and predictive biomarkers are urgently needed. Mutations in KMT2C and KMT2D lead to increased levels of genomic instability. Therefore, we aimed to examine whether KMT2C/D mutations might be a predictor of immunotherapeutic efficacy. Here, we investigated the associations of KMT2C/D loss-of-function (LOF) variants with tumor mutation burden (TMB), MSI-H, PD-L1 expression, the levels of tumor-infiltrating leukocytes (TILs), and clinical response to ICIs. It was found that KMT2C/D LOF variants were associated with higher TMB. Compared with the non-LOF group, the proportion of patients with MSI-H tumors was larger in the LOF group. PD-L1 expression was higher in the LOF group only for colorectal cancer in both the Chinese and The Cancer Genome Atlas cohorts. Importantly, KMT2C/D LOF variants were associated with decreased regulatory T cells and increased levels of CD8⁺ T cells, activated NK cells, M1 macrophages, and M2 macrophages in colorectal cancer. However, there was no significant association between KMT2C/D LOF and TILs levels in other cancer types. Consistently, the results showed that KMT2C/D LOF variants were associated with prolonged overall survival only in colorectal cancer (p = 0.0485). We also presented that patients with KMT2C/D LOF mutations exhibited a better clinical response to anti-PD-1 therapy in a Chinese colorectal cancer cohort (p = 0.002). Taken together, these results suggested that KMT2C/D LOF variants could be a useful predictor for ICIs efficacy in colorectal cancer. In addition, the predictive value of KMT2C/D LOF variants was consistent with their association with TILs levels.     

分子医学助力健康中国

"健康中国"战略是我国的基本国策,是促进我国卫生健康事业发展和提升人民健康水平的重要抓手,是推动我国医疗健康产业发展的重要引擎。以科技创新引领卫生健康事业发展,推动"健康中国"建设是科技工作者义不容辞的责任。现代医学已经进入分子医学时代,需要从分子水平去了解疾病发生、发展的过程和机制,从分子水平对疾病进行诊断和治疗,以及从分子水平预防预测疾病的发生。分子医学与分子科学、分子生物学相辅相生,发展分子医学依赖于分子科学家不断向生命健康领域深度进军。全文从我国医疗现状出发,阐述了发展分子医学的必要性,并以新冠病毒检测和生物医药研发的两个应用案例,介绍本研究团队在发展分子医学,造福人类健康上做出的探索。     

The SWI/SNF chromatin remodeling complexes BAF and PBAF differentially regulate epigenetic transitions in exhausted CD8+ T cells

1. Download : Download high-res image (230KB)
2. Download : Download full-size image

     

Age-dependent differences in efferocytosis determine the outcome of opsonophagocytic protection from invasive pathogens

1. Download : Download high-res image (126KB)
2. Download : Download full-size image

     

Tislelizumab plus chemotherapy as first-line treatment for recurrent or metastatic nasopharyngeal cancer: A multicenter phase 3 trial (RATIONALE-309)

Download : Download video (256MB)