Sartore-Bianchi Andrea, Siena Salvatore
Niguarda Cancer Center, Grande Ospedale Metropolitano Niguarda, Piazza Ospedale Maggiore, 3, 20162, Milan, Italy.
Dipartimento di Oncologia ed Emato-Oncologia, Università degli Studi di Milano, Milan, Italy.
Handb Exp Pharmacol. 2018;249:145-159. doi: 10.1007/164_2017_19.
Colorectal cancer (CRC) is one of the most prevalent cancers and the second leading cause of cancer mortality worldwide. Survival in the metastatic setting has been gradually improved by the addition to cytotoxic chemotherapy of agents targeting the vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR). Considerable heterogeneity exists within CRC due to the varied genetic and epigenetic mechanisms involved in differing pathways of carcinogenesis. The knowledge of molecular abnormalities underlying colorectal tumourigenesis and the progression of dysplastic precursors to invasive and ultimately metastatic lesions has advanced in recent years by comprehensive sequencing studies. From these genome-scale analyses, we know that a handful of genes are commonly affected by somatic mutations, whereas recurrent copy-number alterations and chromosomal translocations are rarer in this disease. Even though some of these molecular abnormalities make genes acting as drivers of cancer progression, translation of this recognition for therapeutic purposes is still limited, encompassing only as standard of care the exclusion of RAS-mutated cancers for better selecting patients to candidate to EGFR-targeted therapy with monoclonal antibodies. However, the effort of ameliorating molecular selection should not be considered exhausted by demonstration of RAS and BRAF-induced resistance, as the genomic landscape of response to EGFR blockade has been demonstrated to be wider and dynamically multifaceted. In this chapter we will review main molecular biomarkers of de novo (primary) and acquired (secondary) resistance to EGFR-targeted monoclonal antibodies in metastatic CRC and discuss therapeutic implications.
结直肠癌（CRC）是全球最常见的癌症之一，也是癌症死亡的第二大主要原因。通过在细胞毒性化疗中添加靶向血管内皮生长因子（VEGF）和表皮生长因子受体（EGFR）的药物，转移性结直肠癌患者的生存率已逐步提高。由于参与不同致癌途径的遗传和表观遗传机制不同，结直肠癌存在相当大的异质性。近年来，通过全面的测序研究，对结直肠肿瘤发生以及发育异常前体向侵袭性、最终转移性病变进展的分子异常的认识有了进展。从这些基因组规模的分析中，我们知道少数基因通常受体细胞突变影响，而在这种疾病中，复发性拷贝数改变和染色体易位则较为罕见。尽管这些分子异常中的一些使基因成为癌症进展的驱动因素，但将这种认识转化为治疗目的仍然有限，仅作为标准治疗，排除RAS突变的癌症，以便更好地选择适合使用单克隆抗体进行EGFR靶向治疗的患者。然而，改善分子选择的努力不应因证明RAS和BRAF诱导的耐药性而被认为已穷尽，因为对EGFR阻断反应的基因组格局已被证明更广泛且动态多面。在本章中，我们将回顾转移性结直肠癌中对EGFR靶向单克隆抗体的原发（初始）和获得性（继发）耐药的主要分子生物标志物，并讨论其治疗意义。
