ALK Fusion Research Articles

Performances of the Idylla GeneFusion Assay: contribution to a rapid diagnosis of targetable gene fusions in tumour samples

AimsWe aimed to evaluate the performances of the Idylla GeneFusion Assay (IGFA) designed to detect, in a single, rapid and fully automated assay, ALK, ROS1, RET, NTRK1, NTRK2 and NTRK3...

ALK -rearranged Mesenchymal Neoplasms With Prominent Foamy/Pseudolipogenic Cell Morphology : Expanding the Phenotypic Spectrum of ALK Fusion Neoplasms and Report of Novel Fusion Partners.

The category of ALK -rearranged mesenchymal neoplasms has been evolving rapidly, with reports of morphologically diverse lesions of cutaneous, soft tissue, and visceral origin. While some of these represent morphologically defined entities harboring recurrent ALK fusions (inflammatory myofibroblastic tumor and epithelioid fibrous histiocytoma), others are unclassified by morphology with variable overlap with the tyrosine kinase family of neoplasia and their underlying ALK fusions cannot be suspected based on morphology. We herein report 3 cases that expand the anatomic, morphologic, and genotypic spectrum of ALK -rearranged unclassified neoplasms. Patients were all adults aged 46 to 69 (median: 63) who presented with a mass located in the gingiva, subcutis of the back, and submucosal posterior pharyngeal wall. The tumor size ranged from 1 to 2.7 cm (median: 1.6). Conservative surgery was the treatment in all patients. Follow-up was available for one patient who remained disease-free at 14 months. Histologically, all tumors displayed large polygonal cells with foamy to granular and lipogenic-like microvacuolated copious cytoplasm and medium-sized round nuclei with 1 or 2 prominent nucleoli. Mitoses and necrosis were not seen. The initial diagnostic impression was PEComa, inflammatory rhabdomyoblastic tumor and unclassified pseudolipogenic neoplasm. Strong cytoplasmic ALK was detected by immunohistochemistry in all cases. Other positive markers include Cathepsin K (2/2), desmin (1/3), focal MyoD1 (1/1), focal SMA (1/3), and focal EMA (1/2). Targeted RNA sequencing revealed ALK fusions with exon 20 (2 cases) and exon 19 (one case) of ALK fused to RND3 (exon 3), SQSTM1 (exon 6), and desmin (intron 6). Methylation profiling in the desmin-fused case (initially diagnosed as inflammatory rhabdomyoblastic tumor) revealed an inflammatory myofibroblastic tumor match with a low confidence score of 0.5 and a flat copy number variation (CNV) profile. No NF1 mutation was detected in this case, altogether excluding an inflammatory rhabdomyoblastic tumor. Our study highlights and expands the morphologic and anatomic diversity of ALK- fused neoplasms and documents novel fusion partners ( RND3 and desmin).

Impact of EML4-ALK Variants and Co-Occurring TP53 Mutations on Duration of First-Line ALK Tyrosine Kinase Inhibitor Treatment and Overall Survival in ALK Fusion-Positive NSCLC: Real-World Outcomes From the GuardantINFORM database

IntroductionTyrosine kinase inhibitors (TKIs) are first-line treatment options for ALK-positive (ALK+) NSCLC. Factors such as variant allele frequencies (VAFs), EML4-ALK fusion variant, and concurrent TP53 mutations (TP53mt) in circulating tumor DNA (ctDNA) may affect treatment outcomes. We evaluated their effects on time to discontinuation (TTD) of first-line treatment with next-generation ALK TKIs in a real-world setting. MethodsAdults with advanced or metastatic NSCLC and ctDNA-detected ALK fusion who received first-line next-generation ALK TKI monotherapy were identified in GuardantINFORM. Effects of ALK fusion VAF, EML4-ALK variants, and TP53mt detection on TTD were evaluated. ResultsA total of 307 patients with ALK fusion in baseline ctDNA received first-line alectinib (n = 280), brigatinib (n = 15), lorlatinib (n = 9), or ceritinib (n = 3); 150 patients (49%) had ALK-fusion VAF greater than or equal to 1%. Among 232 patients with EML4-ALK fusions (v1, 50%; v3, 36%), TP53mt co-occurred with v1 in 42 (18%) and v3 in 32 (14%). Patients with VAF less than 1% versus greater than or equal to 1% had a median TTD of 32.2 (95% confidence interval [CI]: 20.7–not estimable [NE]) versus 14.7 months (10.4–19.9; hazard ratio [HR] = 1.57 [95% CI: 1.09–2.26]; p = 0.0146). Median TTD was 13.1 (9.5–19.9) versus 27.6 months (17.3–NE) in patients with versus without TP53mt detected (HR = 1.53 [1.07–2.19]; p = 0.0202) and 20.3 (14.4–NE) versus 11.5 months (7.4–31.1) in patients with v1 versus v3 (HR = 1.29 [0.83–2.01]; p = 0.2641). Patients with TP53mt and v3 had a median TTD of 7.4 months (95% CI: 4.2–31.1). ConclusionHigh ctDNA VAF, EML4-ALK v3, and TP53mt were associated with early discontinuation of first-line ALK TKIs.

Fusion Genes Landscape of Lung Cancer Patients From Inner Mongolia, China.

Lung cancer is the leading cause of cancer-related deaths globally. Gene fusion, a key driver of tumorigenesis, has led to the identification of numerous driver gene fusions for lung cancer diagnosis and treatment. However, previous studies focused on Western populations, leaving the possibility of unrecognized lung cancer-associated gene fusions specific to Inner Mongolia due to its unique genetic background and dietary habits. To address this, we conducted DNA sequencing analysis on tumor and adjacent nontumor tissues from 1200 individuals with lung cancer in Inner Mongolia. Our analysis established a comprehensive fusion gene landscape specific to lung cancer in Inner Mongolia, shedding light on potential region-specific molecular mechanisms underlying the disease. Compared to Western cohorts, we observed a higher occurrence of ALK and RET fusions in Inner Mongolian patients. Additionally, we discovered eight novel fusion genes in three patients: SLC34A2-EPHB1, CCT6P3-GSTP1, BARHL2-APC, HRAS-MELK, FAM134B-ERBB2, ABCB1-GIPC1, GPR98-ALK, and FAM134B-SALL1. These previously unreported fusion genes suggest potential regional specificity. Furthermore, we characterized the fusion genes' structures based on breakpoints and described their impact on major functional gene domains. Importantly, the identified novel fusion genes exhibited significant clinical and pathological relevance. Notably, patients with SLC34A2-EPHB1, CCT6P3-GSTP1, and BARHL2-APC fusions showed sensitivity to the combination of chemotherapy and immunotherapy. Patients with HRAS-MELK, FAM134B-ERBB2, and ABCB1-GIPC1 fusions showed sensitivity to chemotherapy. In summary, our study provides novel insights into the frequency, distribution, and characteristics of specific fusion genes, offering valuable guidance for the development of effective clinical treatments, particularly in Inner Mongolia.

Clinical, Imaging, and Pathological-Molecular Characteristics Associated with Stage IA Invasive Lung Adenocarcinoma Recurrence After Sub-lobar Resection

Rationale and ObjectivesThis study aimed to investigate the association of clinical, imaging, and pathological-molecular characteristics with the prediction of patient prognosis with stage IA invasive lung adenocarcinoma (ILADC) after sub-lobar resection. Materials and MethodsThis study assessed 360 patients, including 91 and 269 with and without recurrence 3 years postoperativel, respectively, with stage IA ILADC undergoing preoperative chest computed tomography (CT) scans and subsequent sub-lobar resection at our institution. Their clinical and CT features and histological subtypes and gene mutation status were compared. Binary logistic regression analysis was conducted to identify the independent risk factors for recurrence. An external validation cohort included 113 patients, used to test the model’s efficiency. ResultsFor clinical features, old age, male gender, smokers, and high age-adjusted Charlson comorbidity index (ACCI) were frequently observed in patients with recurrence than those without (all p < 0.05). For CT features, large tumor size, solid-predominant density, spiculation, peripheral fibrosis, type II pleural tag, and pleural adhesion were more common in recurrent patients than non-recurrent ones (all p < 0.05). The regression model revealed old age, large tumor size, solid-predominant density, spiculation, type II pleural tag, and pleural adhesion as independent risk factors for recurrence, with an area under the curve (AUC) of 0.942. The external validation cohort obtained an AUC of 0.958. For phological-molecular features, miropapillary/solid-predominant growth pattern, KRAS, ALK, and NRAS mutation or fusion were more ccommon in the recurrent group, whereas EGFR mutation was more frequent in the non-recurrent group (all p < 0.05). ConclusionClinical and CT features help predict the prognosis of patients with stage IA ILADC after sub-lobar resection and decide for individualized treatment. Moreover, patients with different prognosis demonstrated different pathological-molecular features.

Identification and Application of Emerging Biomarkers in Treatment of Non-Small-Cell Lung Cancer: Systematic Review.

Non-small-cell lung cancer (NSCLC) comprises approximately 85% of all lung cancer cases, often diagnosed at advanced stages, which diminishes the effective treatment options and survival rates. This systematic review assesses the utility of emerging biomarkers-circulating tumor DNA (ctDNA), microRNAs (miRNAs), and the blood tumor mutational burden (bTMB)-enhanced by next-generation sequencing (NGS) to improve the diagnostic accuracy, prognostic evaluation, and treatment strategies in NSCLC. Analyzing data from 37 studies involving 10,332 patients from 2020 to 2024, the review highlights how biomarkers like ctDNA and PD-L1 expression critically inform the selection of personalized therapies, particularly beneficial in the advanced stages of NSCLC. These biomarkers are critical for prognostic assessments and in dynamically adapting treatment plans, where high PD-L1 expression and specific genetic mutations (e.g., ALK fusions, EGFR mutations) significantly guide the use of targeted therapies and immunotherapies. The findings recommend integrating these biomarkers into standardized clinical pathways to maximize their potential in enhancing the treatment precision, ultimately fostering significant advancements in oncology and improving patient outcomes and quality of life. This review substantiates the prognostic and predictive value of these biomarkers and emphasizes the need for ongoing innovation in biomarker research.

HGG-38. COMBINING TARGETED THERAPY AND RADIATION OUTPERFORMS SINGLE TREATMENTS IN PEDIATRIC HIGH-GRADE GLIOMA

Abstract BACKGROUND Pediatric-type diffuse high-grade gliomas (pHGGs) are a diverse group of central nervous system tumors in children and adolescents with typically fatal outcomes. Addressing this disease requires new treatment approaches to enhance both survival and quality of life for affected patients. Recently, targeting oncogenic receptor tyrosine kinases (RTKs) has provided promising initial responses in different pHGG subtypes. However, even in these cases, the disease invariably relapses. METHODS We utilized murine tumor cell cultures carrying oncogenic alterations in different RTKs, such as an NTRK fusion, an ALK fusion and activating FGFR1 mutations to evaluate the synergy of radiotherapy and a variety of specific small molecule inhibitors using viability and apoptosis assays. By conducting pharmacokinetic analyses in murine models, we quantified the availability of selected compounds in the mouse brain in vivo, informing downstream preclinical experiments. RESULTS We found that concomitant radiation potentiated the antitumor effect of all tested targeted compounds, mostly outperforming calculated additivity of single treatments. Of note, the level of potentiation was comparable between different inhibitors targeting the same RTK, but was highly dependent on the underlying tumor genotype. Using erdafitinib or futibatinib and a dose of 2 Gy in a FGFR1-driven pHGG model, the combined treatment resulted in a remarkably high late apoptosis rate of 90%, warranting ongoing in vivo studies. Through pharmacokinetic analyses, we identified that among all tested small-molecule-inhibitors, only lorlatinib and futibatinib reach clinically relevant concentrations in the murine brain. CONCLUSIONS Our preliminary data showed that the combination of targeted therapy and radiation elicits encouraging anti-tumor effects in different pHGG cultures. We are currently performing preclinical in vivo studies using immunocompetent orthotopic mouse models to evaluate benefits of combined treatment. Our data will inform future clinical trials and hopefully improve the prognosis and quality of life for a fraction of pediatric patients diagnosed with pHGG.

HGG-35. SIGNIFICANT RESPONSE TO LAROTRECTINIB AS FIRST LINE THERAPY IN INFANT WITH INFANT-TYPE HEMISPHERIC GLIOMA

Abstract BACKGROUND Infant-type hemispheric gliomas represent a recent WHO classification of high grade pediatric brain tumors that are often characterized by NTRK, ROS1, MET or ALK fusions. Novel agents may target their driver mutations but are not yet considered front line therapy. METHODS Patient data was reviewed retrospectively through chart review. RESULTS A 7 day old male infant who presented with vomiting, shaking and a full fontanelle was found to have a 8.7 x 7.2 x 9.3 cm solid and cystic mass with internal hemorrhage in the right parietal and occipital lobes associated with significant mass effect and midline shift. He underwent VP shunt placement and tumor biopsy, but later developed seizures and declining mental status. Cyst decompression was used as stabilizing measure. Due to his very small size and tenuous clinical status full tumor resection was not feasible at that time. Pathology revealed an infant-type hemispheric glioma with ETV6-NTRK3 fusion. Although cytogenetic testing for NTRK alterations was negative, the fusion was confirmed by NGS. Given his age and the risks for electrolyte imbalances and cytopenias in a patient with recent hemorrhage, we elected to treat with Larotrectinib instead of traditional cytotoxic chemotherapy. He had notable disease response within 8 weeks and remains on drug 18 months later with continued response. His tumor now measures 2 x 1.5 x 1.6 cm. He has had one grade 3 toxicity with neutropenia, which was likely impacted by viral bone marrow suppression. He is currently meeting most developmental milestones but does have orthotics and sees speech therapy. CONCLUSIONS Targeted agents may represent a viable front line therapy to decrease tumor mass and temporize very young patients until they can undergo definitive resection and therapy. Future clinical trials will need to compare efficacy to current standards of care.

ETMR-31. A UNIQUE CASE OF CNS DIFFUSE, NON-SYSTEMIC ALK+ HISTIOCYTOSIS IN A PEDIATRIC PATIENT

Abstract BACKGROUND Histiocytic disorders are a group of rare diseases with accumulation of of macrophages, monocytes, or dendritic cells in various parts of the body. ALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 that is very rarely described in pediatrics. METHODS A 20 month old male presented to an adult hospital after a prolonged period of headaches, vomiting, and loss of developmental milestones. Imaging demonstrated severe hydrocephalus and extensive thickened leptomeningeal enhacement with mass effect. He underwent VP shunt placement and revision, a T7-T10 laminectomy, and tumor debulking. Extensive molecular testing, including DNA and RNA analysis by NGS was performed and a CLTC::ALK fusion was identified, along with Tier III DNA variants, yielding a diagnosis consistent with ALK-Positive Histiocytosis, with diffusivity in the CNS system. Full evaluation demonstrated no involvement of the peripheral nervous system or other systemic involvement. He initially demonstrated signs of neuro-irritation, altered tone, and lower extremity clonus. RESULTS After review of very little literature published on similar patients, although none with a clinical picture matching his, he was started on a treatment course of high dose dexamethasone, vinblastine, and lorlatinib targeting the ALK+, likely driver, mutation of his disease. On evaluation scans two months into treatment, he showed no change in his disease burden. He was transitioned to clofarabine cycles with daily lorlatinib for continued targetted therapy. After six total cycles, he demonstrated a high partial to complete remission (allowing for evidence of scarred tissue) and tremendous neurologic and developmental milestone gains. CONCLUSIONS This case demonstrates a unique presentation in which there is little described in the literature in way of clinical features or treatment standards, and further none exactly similar to this patient. After undergoing extensive evaluation and therapy modication, he responded remarkably well and continues to have optimal quality of life.

Shifting from Immunohistochemistry to Screen for ALK Rearrangements: Real-World Experience in a Large Single-Center Cohort of Patients with Non-Small-Cell Lung Cancer.

The identification of ALK fusions in advanced non-small-cell lung carcinoma (aNSCLC) is mandatory for targeted therapy. The current diagnostic approach employs an algorithm using ALK immunohistochemistry (IHC) screening, followed by confirmation through ALK FISH and/or next-generation sequencing (NGS). Challenges arise due to the infrequency of ALK fusions (3-7% of aNSCLC), the suboptimal specificity of ALK IHC and ALK FISH, and the growing molecular demands placed on small tissue samples, leading to interpretative, tissue availability, and time-related issues. This study investigates the effectiveness of RNA NGS as a reflex test for identifying ALK fusions in NSCLC, with the goal of replacing ALK IHC in the systematic screening process. The evaluation included 1246 NSCLC cases using paired techniques: ALK IHC, ALK FISH, and ALK NGS. ALK IHC identified 51 positive cases (4%), while RNA NGS detected ALK alterations in 59 cases (4.8%). Of the 59 ALK-positive cases identified via NGS, 53 (89.8%) were confirmed to be positive. This included 51 cases detected via both FISH and IHC, and 2 cases detected only via FISH, as they were completely negative according to IHC. The combined reporting time for ALK IHC and ALK FISH averaged 13 days, whereas ALK IHC and RNA NGS reports were obtained in an average of 4 days. These results emphasize the advantage of replacing systematic ALK IHC screening with RNA NGS reflex testing for a more comprehensive and accurate assessment of ALK status.

STRN::ALK fusion renal cell carcinoma with lung metastasis: report of a case

STRN::ALK fusion renal cell carcinoma with lung metastasis: report of a case

ALK-Rearranged Renal Cell Carcinoma: A Multi-Institutional Study of 9 Cases With Expanding the Morphologic and Molecular Genetic Spectrum

ALK-rearranged renal cell carcinoma (ALK-RCC) is rare, molecularly defined RCC subtype in the recently published fifth edition of World Health Organization classification of tumors. In this study, we described 9 ALK-RCCs from a clinicopathologic, immunohistochemical, and molecular genetic aspect, supporting and extending upon the observations by previous studies regarding this rare subgroup of RCC. There were 6 male and 3 female patients with ages ranging from 14 to 59 years (mean, 34.4 years). None of the patients had sickle cell trait. The diagnosis was based on radical or partial nephrectomy specimen for 8 patients and on biopsy specimen for 1. Tumor size ranged from 2.5 to 7.2 cm (mean, 2.8 cm). Follow-up was available for 6 of 9 patients (6-36 months); 5 had no tumor recurrence or metastasis and 1 developed lung metastasis at 24 months. The patient was subsequently treated with resection of the metastatic tumor followed by crizotinib-targeted therapy, and he was alive without tumor 12 months later. Histologically, the tumors showed a mixed growth of multiple patterns, including papillary, solid, tubular, tubulocystic, cribriform, and corded, often set in a mucinous background. The neoplastic cells had predominantly eosinophilic cytoplasm. Focally, clear cytoplasm with polarized nuclei and subnuclear vacuoles (n = 1), and pale foamy cytoplasm (n = 1) were observed on the tumor cells. The biopsied tumor showed solid growth of elongated tubules merging with bland spindle cells. Other common and uncommon features included psammomatous microcalcifications (n = 5), rhabdoid cells (n = 4), prominent intracytoplasmic vacuoles (n = 4), prominent chronic inflammatory infiltrate (n = 3), signet ring cell morphology (n = 2), and pleomorphic cells (n = 2). By immunohistochemistry, all 9 tumors were diffusely positive for ALK(5A4) and 4 of 8 tested cases showed reactivity for TFE3 protein. By fluorescence in situ hybridization analysis, ALK rearrangement was identified in all the 9 tumors; none of the tested tumors harbored TFE3 rearrangement (0/4) or gains of chromosomes 7 and 17 (0/3). ALK fusion partners were identified by RNA-sequencing in all 8 cases analyzed, including EML4 (n = 2), STRN (n = 1), TPM3 (n = 1), KIF5B (n = 1), HOOK1 (n = 1), SLIT1 (n = 1), and TPM1(3′ UTR) (n = 1). Our study further expands the morphologic and molecular genetic spectrum of ALK-RCC.

ALK-rearranged mesenchymal neoplasms: a clinicopathological and molecular study of eight additional cases of an emerging group of tyrosine kinase fusion mesenchymal tumours

AimsMesenchymal neoplasms characterised by ALK fusions mainly include inflammatory myofibroblastic tumour (IMT) and epithelioid fibrous histiocytoma (EFH). Most recently, ALK-rearranged mesenchymal tumours that are not IMT or EFH have been...

Novel genome-wide significant germline genetic variants associated with venous thrombo-embolism (VTE) and arterial embolism (ATE) risk in patients with ALK and ROS1 fusion non-small cell lung cancer (NSCLC).

12092 Background: In a recent meta-analysis, non small cell lung cancers (NSCLC) with ALK or ROS1 fusions had higher rates of VTE compared to KRAS or EGFR mutant NSCLC, and were associated with increased ATE risk, particularly around diagnosis. The underlying mechanisms of how these somatic fusions affect thrombosis remain unclear. We examined clinico-demographic and germline genetic factors associated with VTE and ATE in NSCLC patients with ALK/ROS1 fusions in this first comprehensive genome wide association analysis (GWAS). Methods: In this prospective cohort, germline DNA from whole blood was obtained from 150 patients with ALK fusions and 32 with ROS1 fusions at Princess Margaret Cancer Centre (recruited 2014- 2023). Clinico-demographic, treatment and outcome data were collected from electronic medical charts. Overall survival (OS) by VTE or ATE status was assessed via Cox regression, treating ATE and VTE as time-varying covariates. Genotyping utilized the Infinium Global Screening Array (v3.0 Illumina); quality-control removed 3 patients from final analysis. Using linear regression, outcomes were weighted; no VTE/ATE events (0), one VTE/ATE event (1), or multiple ATE/VTEs (&gt;2). Global significance was set at p &lt; 5 x10-8 and adjusted for age, sex, body mass index (BMI), and ethnic/population stratification (top 3 principal components). Results: There were 97 females (54%) and 82 males (46%), mean age was 57.4 years, 70% had stage 4 disease, 96% adenocarcinoma; 35% experienced VTE/ATE at any time; 13% had 2+ VTE/ATE events. For those with VTE, 32 scored 1, 22 scored 2 and 6 scored 3 on Khorana score. Higher BMI was a significant risk factor for VTE/ATE (adjusted odds ratio 1.59 per 5-unit increase, p=0.01). Shorter OS was observed in patients with VTE (Hazard ratio (HR)=3.15, p&lt;0.001) and ATE (HR=2.51, p=0.036), compared to those without. Two novel GWAS gene peaks on the Manhattan plot (previously not reported to be associated with VTE/ATE) had globally significant associations with risk of VTE/ATE: at Chromosome 6q15 (intergenic region between RNGTT and LOC101928936; 5/10 top variants with top risk-allele p=3.594E-09) and at 15p22 ( TLN2 gene; 2/10 top variants p=1.095E-08). TLN2 is a cytoskeletal protein involved in the assembly of actin filaments and linkages with extracellular matrices. Additional identified variants potentially associated with VTE/ATE in ALK/ROS1 fusion patients were found in: CTBP2, NALCN, WDR7, PAX7, ZNF385D, SORBS2, and CSMD1. Conclusions: Two novel globally significant variants, associated with VTE/ATE, are unique to patients with ALK/ROS1 fusion NSCLC. If validated, these biomarkers may help identify ALK/ROS1 patients who are at highest risk of VTE/ATE who may benefit from prophylactic anticoagulation. Further investigation and clinical evaluation are warranted.

Comparison and performance of three plasma next-generation sequencing assays versus tissue testing for the detection of actionable driver mutations in advanced non-squamous non-small cell lung carcinoma.

e20018 Background: Liquid biopsy (LB) is a useful tool for the detection of actionable mutations in advanced non-squamous non-small cell lung cancer (NS-NSCLC) at progression. However, the clinical benefits of integrating both LB and tissue biopsy (TB)-based genomic profiling at diagnosis of NS-NSCLC remain uncertain. Methods: We tested three commercially available next-generation sequencing (NGS) gene panel assays in circulating cell-free DNA (cfDNA) using replicate sets of 85 LB samples from advanced NS-NSCLC patients at baseline and compared the results with matched TB for the detection of tier IA/B (AMP/ASCO/CAP classification) alterations. We used methylation testing of cfDNA to assess the tumor fraction (TF). We correlated molecular data with clinico-pathological features and follow-up data. Results: All TB-based NGS results were interpretable. 5 LB-based NGS results for one assay were not performed due to the material exhaustion. Tier IA/B gene alteration was detected by LB-based NGS and TB-based NGS in 18 to 23 (21 to 27%) patients and in 35 (41%) patients, respectively. The positive percent agreement of each LB-based NGS assay method compared with TB-based NGS assay ranged from 51% to 68%. The incremental add provided by first LB-based NGS ranged from 0 to 23% versus 25 to 45% for first TB-based NGS, depending on the LB-based NGS assay. It includes one EGFR uncommon mutation, 9 MET amplifications and 2 HER2 amplifications detected by LB-based NGS assays that were not detected by TB-based NGS. Overall agreement between the three LB-based NGS assays was 44%. Hybrid-capture based assay detects 14 MET/HER2 CNVs, two METex14 skipping mutation and two ALK fusions that were not detected by amplicon-based assay. Amplicon-based assay detects one uncommon EGFR mutation, one KRAS non-G12C and one ALK fusion that were not detected by hybrid-capture based assay. 64 LB samples were tested for cfDNA methylation. Positive predictive value and negative predictive value of the detection of TF by cfDNA methylation profiling was 90% and 92%, respectively. The only false-negative result of TF evaluation by cfDNA methylation profiling was observed for a variant with a cfDNA VAF &lt; 1%. Correlation analyses with clinicopathological data are ongoing. Conclusions: While concordance with tissue is relatively high, the incremental add provided by LB-based NGS at diagnosis of advanced NS-NSCLC compared to TB-based NGS is limited and greatly varies according to the sequencing method used. Thus, LB-based NGS at diagnosis of NSCLC can be used as a complement of TB-based NGS or as an alternative when tissue is not available.

Efficacy of immunotherapy in first-line treatment for non-small cell lung cancer with HER2 mutation: Results from LC-SCRUM-Asia.

8629 Background: HER2 mutations occur in 2–4% of non-small cell lung cancer (NSCLC) patients. Previous studies with small cohorts have showed poor clinical outcomes in HER2-mutant NSCLC patients treated with immune checkpoint inhibitors (ICIs). However, in these previous studies, ICIs had not been used as the first line treatment in advanced NSCLC. Thus, the clinical outcomes in HER2-mutant NSCLC patients treated with ICIs in the first line treatment are still unclear. Methods: Using a large-scale clinical-genomic database of LC-SCRUM-Asia, the clinical-genomic characteristics and therapeutic outcomes of NSCLC patients harboring HER2 mutations were investigated. Tumor mutation burden (TMB) in tumors with HER2 mutations was compared to tumors with EGFR mutations or ALK fusions. Results: From March 2015 to June 2023, 15,251 NSCLC patients enrolled in LC-SCRUM-Asia. HER2 mutations were detected in 402 patients (2.6%). The most common subtype of HER2 mutations was exon 20 in-frame insertions (Ex20ins) (79%), followed by tyrosine kinase domain other than Ex20ins (10%), extracellular domain (7%) and transmembrane domain (3%). The most common Ex20ins was Y772_A775dupYVMA (66%), followed by G776delinsVC (14%), G778_P780dupGSP (7%). A total of 268 patients had received platinum-based chemotherapy with ICI (Chemo-ICI, n = 95) or without ICI (Chemo-alone, n = 173) until October 2022. The median follow-up periods were 18.5 and 19.9 months in the patients received Chemo-ICI and Chemo-alone, respectively. The patients received Chemo-ICI showed a significantly longer progression-free survival (PFS) compared to those received Chemo-alone (median 8.5 vs 6.3 months, HR [95%CI]: 0.66 [0.50–0.88], p &lt; 0.005). In multivariate analysis, the addition of ICI to platinum-based chemotherapy was an independent better prognostic factor for PFS. There was no significant difference in the overall survival between the patients received Chemo-ICI and Chemo-alone (median 31.1 vs 23.3 months, HR [95%CI]: 0.80 [0.57 – 1.12]). The overall response rates were 34.7% and 35.3% in the patients received Chemo-ICI and Chemo-alone, respectively. Tumors with HER2 mutations showed a higher TMB (median 4.22 mut/Mb) and a higher percentage of TMB≥10 mut/Mb (12.3%) compared to tumors with EGFR mutations (median 2.54 mut/Mb and 1.0%, respectively) or ALK fusions (median 2.52 mut/Mb and 0.8%, respectively). The subtype of HER2 mutations showed no significant difference in the clinical outcomes of Chemo-ICI and Chemo-alone. Conclusions: Our large cohort demonstrated that the addition of ICI to platinum-based chemotherapy as first line treatment may improve PFS in NSCLC patients with HER2 mutations. Relatively high TMB may contribute to prolongation of PFS with ICI.

Efficacy and safety of PD-1 inhibitors plus metronomic oral vinorelbine in elderly pre-treated patients with metastatic non-small-cell lung cancer.

e20556 Background: The subsequent therapy of elderly non-small cell lung cancer (NSCLC) without driver oncogene has always been a challenge due to the poor performance status and multiple comorbidities, especially in those who acquired resistance to programmed cell death protein 1/programmed death-ligand 1 [PD-(L)1] blockade. Metronomic chemotherapy (MCT) is the frequent administration of chemotherapy drugs at lower doses each time which shows a better safety profile, antitumor angiogenesis, and immune modulatory effects compared with traditional chemotherapy. Here we designed an observational study to evaluate the efficacy and safety of PD-1 inhibitors plus metronomic oral vinorelbine(mOV) in elderly pre-treated metastatic NSCLC. Methods: Patients aged 65 years and above who had been histologically or cytologically confirmed unresectable stage III and IV NSCLC were recruited for this study. All the pts had no EGFR mutation, ALK fusions, or ROS1 fusions and received at least one systematic treatment. Pts received PD-1 inhibitors combined with mOV (30mg, TIW1, day 1-3-5 per week) for 6 cycles, followed by PD-1 inhibitors maintenance until disease progression or intolerable toxicities. The primary endpoint was progression-free survival (PFS). The secondary endpoints included overall survival (OS), objective response rate (ORR), disease control rate (DCR), and safety. Results: From May 2020 to June 2023, 23 pts were enrolled in the study. The median age was 70 with 18(78%) males. Median follow-up time was 22.8 months (range 3.9months-41.9months). The median PFS was 5.13 months (95%Cl: 3.1 months-7.1 months) and the median OS was 28.1 months (95%Cl: (15.2 months-NA). The ORR and DCR were 13% (95%C1: 1.44%-27.6%) and 69.6% (95%Cl: 49.2%-89.9%), respectively. The PFS (p = 0.459, HR = 0.671 95%CI 0.233-1.932) and OS (p = 0.483, HR = 1.607 95%CI 0.426-6.056) were similar between those pts who previously received immunotherapy (N = 16, 69.5%) and not. PD-L1 TPS didn’t affect the patient’s PFS (&lt;1% vs≥1%, p = 0.078, HR = 2.648 95%CI 0.895-7.835 ) and OS(&lt;1% vs≥1%, p = 0.306, HR = 2.202 95%CI 0.485-9.989). Adverse events (AEs) of any grade were observed in 20(86.9%) pts of which grade III-IV AEs occurred in 4 (17.4%) pts. These grade III-IV events consisted of interstitial pneumonia, pulmonary infection, leukopenia, and neutropenia. Immune-related adverse events (irAEs) occurred in 4 (17.4%) pts, of which grade III irAEs occurred in 2 (8.7%) patients with interstitial pneumonia. No grade 4 irAEs and grade 5 adverse events even occurred. Conclusions: The regimen of PD-1 inhibitors plus mOV for the subsequent therapy showed good overall survival benefits and safety in elderly patients with metastatic NSCLC without driver oncogene which suggests it is worth further exploration.

Clinical impact of the rapid genomic screening platform for non-small cell lung cancer in Asia-Pacific (LC-SCRUM-AP).

8637 Background: In 2013, a lung cancer genomic screening project (LC-SCRUM-Asia) started in Japan and expanded to other Asia-Pacific countries in October 2022 (LC-SCRUM-AP). The objective of this study is to clarify the characteristics of genomic profile in Asia-Pacific countries outside of Japan and to elucidate the clinical significance of rapid genomic screening. Methods: To shorten the turnaround time (TAT), a central laboratory was set in each participating country. Samples are analyzed by a multi-gene PCR assay and a rapid next-generation sequencing assay. Clinical, pathological and genomic data are stocked as a clinical-genomic database in each participating country, which is combined with Japanese database and the integrated clinical-genomic database of the Asia-Pacific region was established. Results: A multi-gene PCR assay data was available in 7879 samples from 4 Asia-Pacific countries (Taiwan/Thailand/Malaysia/Japan = 126/65/30/7658 pts). The rates of driver alterations in never-smokers with non-squamous histology were similar in the 4 Asia-Pacific countries: 83%, 80%, 89% and 75% in Taiwan, Thailand, Malaysia, and Japan, respectively. The pattern of genomic profile was also similar among these 4 countries. The median TAT was 4 days and 5 days in Japanese cohort and Taiwan/Thailand/Malaysia cohort, respectively. In Taiwan/Thailand/Malaysia cohort (n = 221), the genomic analysis successful rate was 99.5%. The rates of genomic alterations detected: EGFR (35%) of which ex20ins (6%), KRAS (10%) of which G12C (4%), ALK fusions (6%), ROS1 fusions (4%), RETfusions (0.5%), HER2ex20ins (4%), MET ex14skip (3%), BRAF V600E (1.5%), and NTRK3 fusions (0.5%). Oncogenic driver alterations were detected in 149 pts, of which 102 (68%) pts received targeted therapies approved in each country. 14 patients were enrolled into clinical trials of the investigational drugs, of which 5 were for targeting rare driver alterations. Conclusions: LC-SCRUM-AP is the first international genomic screening platform established in the Asia-Pacific region, which enables the efficient detection of rare driver alterations with a short TAT, contributing to the high implementation rate of targeted therapies. The similar pattern of genomic profile in the 4 Asia-Pacific countries indicates the utility of this screening platform as the basis for the clinical trials for NSCLC with rare driver alterations. We plan to further expand the number of institutions and participating countries.

Hidrocystoma-like tumours with RET or ALK fusion: a study of four cases

Hidrocystoma is thought to be a benign retention cyst of sweat ductal units. The lesion is usually located in the periorbital skin; however, lesions with similar histopathological features are rarely observed in extra-facial sites. Herein, we present four cases of hidrocystoma-like tumours in extra-facial skin sites that harboured a RET or ALK rearrangement. This study features a 67-year-old female with a 10 mm-sized digital tumour (Case 1), a 62-year-old male with an 8 mm-sized clavicular tumour (Case 2), a 61-year-old male with a 19 mm-sized digital tumour (Case 3), and an 11-year-old female with a 10 mm-size lower leg tumour (Case 4) as well as five control cases (Cases 5-9) of classical periorbital hidrocystoma. In Cases 1-4, multicystic tumours comprising a two-cell layer of inner cuboidal ductoglandular (p63- and SOX10+/-) and outer flat myoepithelial (p63+ and SOX10+) cells were observed. The inner ductoglandular tumour cells exhibited micropapillary projections and Roman bridging structures. No apparent atypical cells were observed. NCOA4::RET in Cases 1 and 3, CCDC6::RET in Case 2, and SLC12A2::ALK in Case 4 were revealed by next-generation sequencing or Sanger sequencing. In contrast, control cases of classical hidrocystoma (Cases 5-9) did not show intracystic proliferation, abundant cytoplasm, ALK immunoreactivity, or NCOA4::RET detection in the tumour cells. RET/ALK-rearranged hidrocystoma-like tumours are tumour entities that can be distinguished from classical hidrocystoma. This RET/ALK-rearranged neoplasm is benign and is frequently observed in the digits. Future studies will establish the concept, detailed clinicopathological characteristics, and genetic variations of hidrocystoma-like tumours.

Long-term survival of patients with lung cancer with kinase fusions (KF) treated at a tertiary community-based cancer program.

e23279 Background: Comprehensive Genomic Profiling (CGP) has been routinely obtained on patients with advanced cancers without standard-of-care therapeutic options managed in our community-based cancer program for more than a decade. Methods: In 2018, we reported that 1% (77 of 7,260 pts) who underwent CGP (Foundation Medicine Inc. hybrid capture based CGP platform) were found to have a KF abnormality (median age 53), including 55 patients (pts) (71%) with non-small cell lung cancer (NSCLC) and 22 (29%) with other malignancies. The incidence of KF in the NSCLC population tested was approximately 5%. Of the 55 patients with NSCLC, 36 pts (65%) had ALK fusions, 12 pts (22%) has RET fusions, 7 pts (13%) had ROS1 fusions. Results: This report describes long-term survival of NSCLC pts with metastatic disease within this population treated with KF targeted therapy for &gt; 5 years. Five pts (9% of NSCLC with a KF; all females; median age 63 [range 57-72]) remain on active therapy a median of 10 years (range 6.5-12 years) from the initiation of therapy. 2 pts have EML4-ALK fusions, 1 pt has EZR-ROS1 fusion, 1 pt has CD74-ROS1 fusion, and 1 pt has ALK PRKAR1A fusion. 2 of 5 pts have continued their initial KF agent while 2 switched &gt;1 times to an alternative KF targeted drug and 1 is currently receiving chemotherapy. Only two pts had the identical KF abnormality. Conclusions: In this series approximately 10% of NSCLC pts with a KF experienced extended survival (greater than five years) despite the presence of metastatic disease, including three patients with brain mets. It is critical to conduct molecular testing on all NSCLC pts for the presence of a kinase fusion abnormality. Treatment directed at this molecular target can result in long-term survival.