Identifying erlotinib-sensitive non-small cell lung carcinoma tumors in mice using [11C]erlotinib PET
作者:Galith Abourbeh、Batel Itamar、Olga Salnikov、Sergey Beltsov、Eyal Mishani
DOI:10.1186/s13550-014-0080-0
日期:2015.12
Non-small cell lung carcinoma (NSCLC) represents approximately 80% of lung cancer cases, and over 60% of these tumors express the epidermal growth factor receptor (EGFR). Activating mutations in the tyrosine kinase (TK) domain of the EGFR are detected in 10% to 30% of NSCLC patients, and evidence of their presence is a prerequisite for initiation of first-line therapy with selective TK inhibitors (TKIs), such as gefitinib and erlotinib. To date, the selection of candidate patients for first-line treatment with EGFR TKIs requires an invasive tumor biopsy to affirm the mutational status of the receptor. This study was designed to evaluate whether positron emission tomography (PET) of NSCLC tumor-bearing mice using [11C]erlotinib could distinguish erlotinib-sensitive from erlotinib-insensitive or erlotinib-resistant tumors. Four human NSCLC cell lines were employed, expressing either of the following forms of the EGFR: (i) the wild-type receptor (QG56 cells), (ii) a mutant with an exon 19 in-frame deletion (HCC827 cells), (iii) a mutant with the exon 21 L858R point mutation (NCI-H3255 cells), and (iv) a double mutant harboring the L858R and T790M mutations (NCI-H1975 cells). Sensitivity of each cell line to the anti-proliferative effect of erlotinib was determined in vitro. In vivo PET imaging studies following i.v. injection of [11C]erlotinib were carried out in nude mice bearing subcutaneous (s.c.) xenografts of the four cell lines. Cells harboring activating mutations in the EGFR TK domain (HCC827 and NCI-H3255) were approximately 1,000- and 100-fold more sensitive to erlotinib treatment in vitro, respectively, compared to the other two cell lines. [11C]Erlotinib PET scans could differentiate erlotinib-sensitive tumors from insensitive (QG56) or resistant (NCI-H1975) tumors already at 12 min after injection. Nonetheless, the uptake in HCC827 tumors was significantly higher than that in NCI-H3255, possibly reflecting differences in ATP and erlotinib affinities between the EGFR mutants. [11C]Erlotinib imaging in mice differentiates erlotinib-sensitive NSCLC tumors from erlotinib-insensitive or erlotinib-resistant ones.
非小细胞肺癌(NSCLC)约占肺癌病例的80%,其中超过60%的肿瘤表达表皮生长因子受体(EGFR)。在EGFR的酪氨酸激酶(TK)结构域中,激活突变在NSCLC患者中的检出率为10%至30%,而这些突变的存在是启动选择性TK抑制剂(如吉非替尼和厄洛替尼)一线治疗的前提。迄今为止,为了确认受体的突变状态,选择适合一线EGFR TKI治疗的候选患者需要进行侵入性的肿瘤活检。本研究旨在评估使用[11C]厄洛替尼对NSCLC荷瘤小鼠进行正电子发射断层扫描(PET)是否能区分对厄洛替尼敏感、不敏感或耐药的肿瘤。研究采用了四种人类NSCLC细胞系,它们表达以下形式的EGFR之一:(i)野生型受体(QG56细胞),(ii)含有外显子19移码缺失的突变体(HCC827细胞),(iii)含有外显子21 L858R点突变的突变体(NCI-H3255细胞),以及(iv)携带L858R和T790M双重突变的突变体(NCI-H1975细胞)。在体外测定了各细胞系对厄洛替尼抗增殖作用的敏感性。对移植了这四种细胞系皮下异种移植瘤的裸鼠进行了静脉注射[11C]厄洛替尼后的体内PET成像研究。携带EGFR TK域激活突变的细胞系(HCC827和NCI-H3255)在体外对厄洛替尼治疗的敏感性分别比其他两个细胞系高出约1000倍和100倍。[11C]厄洛替尼PET扫描能在注射后12分钟就区分出对厄洛替尼敏感的肿瘤与不敏感(QG56)或耐药(NCI-H1975)的肿瘤。然而,HCC827肿瘤中的摄取显著高于NCI-H3255肿瘤,这可能反映了EGFR突变体之间在ATP和厄洛替尼亲和力上的差异。在鼠中,[11C]厄洛替尼成像能区分对厄洛替尼敏感的NSCLC肿瘤与不敏感或耐药的肿瘤。