Brunekreeft Kim L, Strohm Corinna, Gooden Marloes J, Rybczynska Anna A, Nijman Hans W, Grigoleit Götz U, Helfrich Wijnand, Bremer Edwin, Siegmund Daniela, Wajant Harald, de Bruyn Marco
Department of Obstetrics and Gynecology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Mol Cancer. 2014 Apr 17;13:85. doi: 10.1186/1476-4598-13-85.
Stimulation of CD40 can augment anti-cancer T cell immune responses by triggering effective activation and maturation of antigen-presenting cells (APCs). Although CD40 agonists have clinical activity in humans, the associated systemic activation of the immune system triggers dose-limiting side-effects.
To increase the tumor selectivity of CD40 agonist-based therapies, we developed an approach in which soluble trimeric CD40L (sCD40L) is genetically fused to tumor targeting antibody fragments, yielding scFv:CD40L fusion proteins. We hypothesized that scFv:CD40L fusion proteins would have reduced CD40 agonist activity similar to sCD40L but will be converted to a highly agonistic membrane CD40L-like form of CD40L upon anchoring to cell surface exposed antigen via the scFv domain.
Targeted delivery of CD40L to the carcinoma marker EpCAM on carcinoma cells induced dose-dependent paracrine maturation of DCs ~20-fold more effective than a non-targeted control scFv:CD40L fusion protein. Similarly, targeted delivery of CD40L to the B cell leukemia marker CD20 induced effective paracrine maturation of DCs. Of note, the CD20-selective delivery of CD40L also triggered loss of cell viability in certain B cell leukemic cell lines as a result of CD20-induced apoptosis.
Targeted delivery of CD40L to cancer cells is a promising strategy that may help to trigger cancer-localized activation of CD40 and can be modified to exert additional anti-cancer activity via the targeting domain.
刺激CD40可通过触发抗原呈递细胞（APC）的有效激活和成熟来增强抗癌T细胞免疫反应。尽管CD40激动剂在人类中有临床活性，但免疫系统的相关全身激活会引发剂量限制性副作用。
为了提高基于CD40激动剂的疗法的肿瘤选择性，我们开发了一种方法，即将可溶性三聚体CD40L（sCD40L）与肿瘤靶向抗体片段进行基因融合，产生scFv:CD40L融合蛋白。我们假设scFv:CD40L融合蛋白将具有与sCD40L相似的降低的CD40激动剂活性，但在通过scFv结构域锚定到细胞表面暴露的抗原后，将转化为高度激动性的膜CD40L样形式的CD40L。
将CD40L靶向递送至癌细胞上的癌标志物EpCAM可诱导树突状细胞（DC）的剂量依赖性旁分泌成熟，其效率比非靶向对照scFv:CD40L融合蛋白高约20倍。同样，将CD40L靶向递送至B细胞白血病标志物CD20可诱导DC的有效旁分泌成熟。值得注意的是，由于CD20诱导的细胞凋亡，CD40L的CD20选择性递送还触发了某些B细胞白血病细胞系中细胞活力的丧失。
将CD40L靶向递送至癌细胞是一种有前景的策略，可能有助于触发癌症局部的CD40激活，并且可以通过靶向结构域进行修饰以发挥额外的抗癌活性。
