{"title":"RET Fusion Testing in Patients With NSCLC: The RETING Study","authors":"Esther Conde MD, PhD , Susana Hernandez PhD , Jose Luis Rodriguez Carrillo MD , Rebeca Martinez APT , Marta Alonso APT , Daniel Curto MD , Beatriz Jimenez MD , Alejandra Caminoa MD, PhD , Amparo Benito MD , Pilar Garrido MD, PhD , Sergi Clave PhD , Edurne Arriola MD, PhD , Isabel Esteban-Rodriguez MD, PhD , Javier De Castro MD, PhD , Irene Sansano MD , Enriqueta Felip MD, PhD , Federico Rojo MD, PhD , Manuel Dómine MD, PhD , Ihab Abdulkader MD, PhD , Jorge Garcia-Gonzalez MD , Fernando Lopez-Rios MD, PhD","doi":"10.1016/j.jtocrr.2024.100653","DOIUrl":null,"url":null,"abstract":"<div><h3>Introduction</h3><p><em>RET</em> inhibitors with impressive overall response rates are now available for patients with NSCLC, yet the identification of <em>RET</em> fusions remains a difficult challenge. Most guidelines encourage the upfront use of next-generation sequencing (NGS), or alternatively, fluorescence in situ hybridization (FISH) or reverse transcriptase-polymerase chain reaction (RT-PCR) when NGS is not possible or available. Taken together, the suboptimal performance of single-analyte assays to detect <em>RET</em> fusions, although consistent with the notion of encouraging universal NGS, is currently widening some of the clinical practice gaps in the implementation of predictive biomarkers in patients with advanced NSCLC.</p></div><div><h3>Methods</h3><p>This situation prompted us to evaluate several <em>RET</em> assays in a large multicenter cohort of <em>RET</em> fusion–positive NSCLC (n = 38) to obtain real-world data. In addition to RNA-based NGS (the criterion standard method), all positive specimens underwent break-apart <em>RET</em> FISH with two different assays and were also tested by an RT-PCR assay.</p></div><div><h3>Results</h3><p>The most common <em>RET</em> partners were <em>KIF5B</em> (78.9%), followed by <em>CCDC6</em> (15.8%). The two <em>RET</em> NGS-positive but FISH-negative samples contained a <em>KIF5B(15)-RET(12)</em> fusion. The three <em>RET</em> fusions not identified with RT-PCR were <em>AKAP13(35)-RET(12)</em>, <em>KIF5B(24)-RET(9)</em> and <em>KIF5B(24)-RET(11)</em>. All three false-negative RT-PCR cases were FISH-positive, exhibited a typical break-apart pattern, and contained a very high number of positive tumor cells with both FISH assays. Signet ring cells, psammoma bodies, and pleomorphic features were frequently observed (in 34.2%, 39.5%, and 39.5% of tumors, respectively).</p></div><div><h3>Conclusions</h3><p>In-depth knowledge of the advantages and disadvantages of the different <em>RET</em> testing methodologies could help clinical and molecular tumor boards implement and maintain sensible algorithms for the rapid and effective detection of <em>RET</em> fusions in patients with NSCLC. The likelihood of <em>RET</em> false-negative results with both FISH and RT-PCR reinforces the need for upfront NGS in patients with NSCLC.</p></div>","PeriodicalId":17675,"journal":{"name":"JTO Clinical and Research Reports","volume":"5 4","pages":"Article 100653"},"PeriodicalIF":3.0000,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666364324000237/pdfft?md5=1d0484197557d1fce0d0732e03259f18&pid=1-s2.0-S2666364324000237-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"JTO Clinical and Research Reports","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2666364324000237","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ONCOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Introduction
RET inhibitors with impressive overall response rates are now available for patients with NSCLC, yet the identification of RET fusions remains a difficult challenge. Most guidelines encourage the upfront use of next-generation sequencing (NGS), or alternatively, fluorescence in situ hybridization (FISH) or reverse transcriptase-polymerase chain reaction (RT-PCR) when NGS is not possible or available. Taken together, the suboptimal performance of single-analyte assays to detect RET fusions, although consistent with the notion of encouraging universal NGS, is currently widening some of the clinical practice gaps in the implementation of predictive biomarkers in patients with advanced NSCLC.
Methods
This situation prompted us to evaluate several RET assays in a large multicenter cohort of RET fusion–positive NSCLC (n = 38) to obtain real-world data. In addition to RNA-based NGS (the criterion standard method), all positive specimens underwent break-apart RET FISH with two different assays and were also tested by an RT-PCR assay.
Results
The most common RET partners were KIF5B (78.9%), followed by CCDC6 (15.8%). The two RET NGS-positive but FISH-negative samples contained a KIF5B(15)-RET(12) fusion. The three RET fusions not identified with RT-PCR were AKAP13(35)-RET(12), KIF5B(24)-RET(9) and KIF5B(24)-RET(11). All three false-negative RT-PCR cases were FISH-positive, exhibited a typical break-apart pattern, and contained a very high number of positive tumor cells with both FISH assays. Signet ring cells, psammoma bodies, and pleomorphic features were frequently observed (in 34.2%, 39.5%, and 39.5% of tumors, respectively).
Conclusions
In-depth knowledge of the advantages and disadvantages of the different RET testing methodologies could help clinical and molecular tumor boards implement and maintain sensible algorithms for the rapid and effective detection of RET fusions in patients with NSCLC. The likelihood of RET false-negative results with both FISH and RT-PCR reinforces the need for upfront NGS in patients with NSCLC.
目前,可用于 NSCLC 患者的导入 RET 抑制剂的总体反应率令人印象深刻,但 RET 融合的鉴定仍是一项艰巨的挑战。大多数指南都鼓励在前期使用新一代测序(NGS),或者在无法使用 NGS 时使用荧光原位杂交(FISH)或反转录聚合酶链反应(RT-PCR)。这种情况促使我们在 RET 融合阳性 NSCLC(n = 38)的大型多中心队列中评估了几种 RET 检测方法,以获得真实世界的数据。除了基于 RNA 的 NGS(标准方法)外,所有阳性标本都接受了两种不同检测方法的 RET FISH 检测,还接受了 RT-PCR 检测。结果最常见的 RET 伴侣是 KIF5B(78.9%),其次是 CCDC6(15.8%)。两个 RET NGS 阳性但 FISH 阴性的样本含有 KIF5B(15)-RET(12) 融合。RT-PCR 未鉴定出的三例 RET 融合为 AKAP13(35)-RET(12)、KIF5B(24)-RET(9) 和 KIF5B(24)-RET(11)。三例 RT-PCR 假阴性病例均为 FISH 阳性,表现出典型的断裂模式,且两种 FISH 检测方法均含有大量阳性肿瘤细胞。结论深入了解不同 RET 检测方法的优缺点有助于临床和分子肿瘤委员会实施和维护合理的算法,快速有效地检测 NSCLC 患者的 RET 融合。FISH和RT-PCR都有可能出现RET假阴性结果,这加强了对NSCLC患者进行前期NGS检测的必要性。