Wolfson Childhood Cancer Research Centre, Newcastle University Centre for Cancer, Translational & Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK.
Newcastle Genetics Laboratory, Newcastle upon Tyne Hospitals NHS Trust, Newcastle upon Tyne, UK.
Genes Chromosomes Cancer. 2022 Dec;61(12):747-753. doi: 10.1002/gcc.23093. Epub 2022 Sep 13.
ALK is the most commonly mutated oncogene in neuroblastoma with increased mutation frequency reported at relapse. Here we report the loss of an ALK mutation in two patients at relapse and a paired neuroblastoma cell line at relapse. ALK detection methods including Sanger sequencing, targeted next-generation sequencing and a new ALK Agena MassARRAY technique were used to detect common hotspot ALK variants in tumors at diagnosis and relapse from two high-risk neuroblastoma patients. Copy number analysis including single nucleotide polymorphism array and array comparative genomic hybridization confirmed adequate tumor cell content in DNA used for mutation testing. Case 1 presented with an ALK F1174L mutation at diagnosis with a variant allele frequency (VAF) ranging between 23.5% and 28.5%, but the mutation was undetectable at relapse. Case 2 presented with an ALK R1257Q mutation at diagnosis (VAF = 39%-47.4%) which decreased to <0.01% at relapse. Segmental chromosomal aberrations were maintained between diagnosis and relapse confirming sufficient tumor cell content for mutation detection. The diagnostic SKNBE1n cell line harbors an ALK F1174S mutation, which was lost in the relapsed SKNBE2c cell line. To our knowledge, these are the first reported cases of loss of ALK mutations at relapse in neuroblastoma in the absence of ALK inhibitor therapy, reflecting intra-tumoral spatial and temporal heterogeneity. As ALK inhibitors are increasingly used in the treatment of refractory/relapsed neuroblastoma, our study highlights the importance of confirming whether an ALK mutation detected at diagnosis is still present in clones leading to relapse.
ALK 是神经母细胞瘤中最常见的突变致癌基因，有研究报道其在复发时的突变频率增加。在这里，我们报告了两名复发患者和一对复发神经母细胞瘤细胞系中 ALK 突变的丢失。我们使用包括 Sanger 测序、靶向下一代测序和新型 ALK Agena MassARRAY 技术在内的 ALK 检测方法，检测了两名高危神经母细胞瘤患者肿瘤初诊和复发时的常见热点 ALK 变异。包括单核苷酸多态性微阵列和比较基因组杂交阵列的拷贝数分析证实，用于突变检测的 DNA 中具有足够的肿瘤细胞含量。病例 1 在初诊时表现出 ALK F1174L 突变，变异等位基因频率（VAF）在 23.5%至 28.5%之间，但在复发时无法检测到该突变。病例 2 在初诊时表现出 ALK R1257Q 突变（VAF=39%-47.4%），在复发时降低至<0.01%。诊断时和复发时的片段性染色体异常保持一致，证实了用于突变检测的肿瘤细胞含量充足。诊断性 SKNBE1n 细胞系携带 ALK F1174S 突变，该突变在复发的 SKNBE2c 细胞系中丢失。据我们所知，这是在没有 ALK 抑制剂治疗的情况下，神经母细胞瘤中首次报道的复发时 ALK 突变丢失的病例，反映了肿瘤内的空间和时间异质性。随着 ALK 抑制剂在治疗难治性/复发性神经母细胞瘤中的应用越来越广泛，我们的研究强调了在克隆导致复发时，确认初诊时检测到的 ALK 突变是否仍然存在的重要性。
