■异柠檬酸脱氢酶(IDH)-野生型胶质母细胞瘤的一种靶向治疗选择集中于具有成纤维细胞生长因子受体3的肿瘤:转化酸性卷曲螺旋蛋白3(FGFR3:TACC3)融合体。FGFR3::TACC3融合检测可能具有挑战性,由于不常规进行靶向RNA下一代测序(NGS),和免疫组织化学是一个不完美的替代标记。融合状态可以使用逆转录聚合酶链反应(RT-PCR)在新鲜冷冻(FF)材料上确定,但有时只有福尔马林固定,石蜡包埋(FFPE)组织是可用的。
■开发RT-PCR测定法以确定FFPE成胶质细胞瘤样品中的FGFR3::TACC3状态。
■对具有353个历史胶质母细胞瘤样品的12个组织微阵列进行FGFR3免疫组织化学染色。FGFR3过表达的样品(n=13)在FFPE上进行FGFR3::TACC3RT-PCR,使用5个引物组检测5个常见的融合变体。用NGS额外分析融合阴性样品(n=6),FGFR3荧光原位杂交(n=6),和RNA测序(n=5)。
■对FGFR3过表达的13个样品的FFPE材料进行RT-PCR,我们在7个样本中检测到FGFR3::TACC3融合,覆盖3种不同的融合变体。对于其中5个FF可用,并且通过在FF上的RT-PCR确认融合体的存在。通过RNA测序,发现1个另外的样品含有FGFR3::TACC3融合物(目前FFPE的RT-PCR未涵盖的变体)。该组中FGFR3::TACC3融合的频率为9/353(2.5%)。
■可以在FFPE材料上成功进行FGFR3::TACC3融合的RT-PCR,具有100%的特异性和(由于有限的引物组)83.3%的灵敏度。当只有福尔马林固定的组织可用时,该测定允许鉴定潜在的靶向治疗选择。
UNASSIGNED: One targeted treatment option for isocitrate dehydrogenase (IDH)-wild-type glioblastoma focuses on tumors with fibroblast growth factor receptor 3::transforming acidic coiled-coil-containing protein 3 (FGFR3::TACC3) fusions. FGFR3::TACC3 fusion detection can be challenging, as targeted RNA next-generation sequencing (NGS) is not routinely performed, and immunohistochemistry is an imperfect surrogate marker. Fusion status can be determined using reverse transcription polymerase chain reaction (RT-PCR) on fresh frozen (FF) material, but sometimes only formalin-fixed, paraffin-embedded (FFPE) tissue is available.
UNASSIGNED: To develop an RT-PCR assay to determine FGFR3::TACC3 status in FFPE glioblastoma samples.
UNASSIGNED: Twelve tissue microarrays with 353 historical glioblastoma samples were immunohistochemically stained for FGFR3. Samples with overexpression of FGFR3 (n = 13) were subjected to FGFR3::TACC3 RT-PCR on FFPE, using 5 primer sets for the detection of 5 common fusion variants. Fusion-negative samples were additionally analyzed with NGS (n = 6), FGFR3 Fluorescence In Situ Hybridization (n = 6), and RNA sequencing (n = 5).
UNASSIGNED: Using RT-PCR on FFPE material of the 13 samples with FGFR3 overexpression, we detected an FGFR3::TACC3 fusion in 7 samples, covering 3 different fusion variants. For 5 of these FF was available, and the presence of the fusion was confirmed through RT-PCR on FF. With RNA sequencing, 1 additional sample was found to harbor an FGFR3::TACC3 fusion (variant not covered by current RT-PCR for FFPE). The frequency of FGFR3::TACC3 fusion in this cohort was 9/353 (2.5%).
UNASSIGNED: RT-PCR for FGFR3::TACC3 fusions can successfully be performed on FFPE material, with a specificity of 100% and (due to limited primer sets) a sensitivity of 83.3%. This assay allows for the identification of potential targeted treatment options when only formalin-fixed tissue is available.