Microenvironmental network of clonal CXCL13+CD4+ T cells and Tregs in pemphigus chronic blisters.

BACKGROUNDPemphigus, a rare autoimmune bullous disease mediated by antidesmoglein autoantibodies, can be controlled with systemic medication like rituximab and high-dose systemic corticosteroids combined with immunosuppressants. However, some patients continue to experience chronically recurrent blisters in a specific area and require long-term maintenance systemic therapy.METHODSSkin with chronic blisters was obtained from patients with pemphigus. Immunologic properties of the skin were analyzed by immunofluorescence staining, bulk and single-cell RNA and TCR sequencing, and a highly multiplex imaging technique known as CO-Detection by indEXing (CODEX). Functional analyses were performed by flow cytometry and bulk RNA-Seq using peripheral blood from healthy donors. Intralesional corticosteroid was injected into patient skin, and changes in chronically recurrent blisters were observed.RESULTSWe demonstrated the presence of skin tertiary lymphoid structures (TLSs) with desmoglein-specific B cells in chronic blisters from patients with pemphigus. In the skin TLSs, CD4+ T cells predominantly produced CXCL13. These clonally expanded CXCL13+CD4+ T cells exhibited features of activated Th1-like cells and downregulated genes associated with T cell receptor-mediated signaling. Tregs are in direct contact with CXCL13+CD4+ memory T cells and increased CXCL13 production of CD4+ T cells through IL-2 consumption and TGF-ß stimulation. Finally, intralesional corticosteroid injection improved chronic blisters and reduced skin TLSs in patients with pemphigus.CONCLUSIONThrough this study we conclude that skin TLSs are associated with the persistence of chronically recurrent blisters in patients with pemphigus, and the microenvironmental network involving CXCL13+CD4+ T cells and Tregs within these structures plays an important role in CXCL13 production.TRIAL REGISTRATIONClinicalTrials.gov NCT04509570.FUNDINGThis work was supported by National Research Foundation of South Korea (NRF-2021R1C1C1007179) and Korea Drug Development Fund, which is funded by Ministry of Science and ICT; Ministry of Trade, Industry, and Energy; and Ministry of Health and Welfare (grant RS-2022-00165917).

Survival Outcomes of Patients with Follicular Lymphoma after Relapse or Progression: A Single-Center Real-World Data Analysis.

Background: Follicular lymphoma (FL) is considered incurable because remission and relapse are common. Although various salvage treatment options have been proposed, there is no consensus on treatment strategy for FL patients who failed primary treatment. Methods: This single-center study analyzed postevent overall survival (OS) among 70 patients who experienced relapse or progression after rituximab-containing immunochemotherapy according to type of salvage treatment and nature of relapse or progression. Results: Of 70 patients, 42 experienced progression of disease within 24 months (POD24), and six showed disease progression during first-line treatment. Large-cell transformation was found in nine patients with POD24. At the median follow-up of 104 months (95% CI: 90-118 months), POD24 patients experienced significantly worse OS than patients without POD24, and postevent OS was not satisfactory after conventional salvage chemotherapy because the majority of patients relapsed or progressed. However, autologous stem cell transplantation (ASCT) after the first relapse resulted in survival prolongation in patients with POD24. Half of the patients (34/67, 51%) participated in at least one clinical trial during treatment after first relapse, and patients participating in at least one clinical trial irrespective of line of treatment tended to experience better survival. Conclusions: Relapsed or refractory FL patients showed various clinical courses and treatment outcomes according to relapse or progression. Consolidation treatment with ASCT and active participation to clinical trials might prolong survival duration, especially in POD24 cases.

Clinical relevance of serum-derived exosomal messenger RNA sequencing in patients with non-Hodgkin lymphoma.

Background: The clinical utility of mRNA cargo in exosomes is unclear, although exosomes have potential as non-invasive biomarkers. This study aimed to investigate the feasibility of exosomal mRNA sequencing for monitoring disease status and predicting outcomes in non-Hodgkin lymphoma (NHL) patients. Methods: Exosomes were isolated from archived serum samples of 33 patients with NHL who were registered into our prospective cohort: diffuse large B-cell lymphoma (DLBCL, n = 17), intravascular B-cell lymphoma (IVL, n = 1), primary mediastinal large B-cell lymphoma (PMBL, n = 4), follicular lymphoma (FL, n = 3), mantle cell lymphoma (MCL, n = 3), and extranodal NK/T-cell lymphoma (ENKTL, n = 5). Exosomal mRNA sequencing was performed, and its concordance with clinical course was analyzed and compared with those of circulating tumor DNA (ctDNA) mutations. Results: Exosomal mRNA sequencing was performed successfully in 26 cases (79%, 26/33), whereas the remaining seven cases were not completed due to their small amount of RNA. The exosomal mRNA sequencing of DLBCL showed gene expression profiles consistent with activated B-cell-like and germinal center type. The longitudinal assessment of exosomal mRNA sequencing results in accordance with the clinical course showed that the post-treatment changes of exosomal mRNA expression were more consistent with treatment outcome than were those of ctDNA mutations. In particular, the exosomal mRNA expression of genes such as BCL2 and BCL6 was increased at the time of disease progression in DLBCL and FL patients. Conclusions: This study demonstrated the feasibility of exosomal mRNA expression profiles as a biomarker for NHL patients. Our results might provide the rationale for studies to explore the potential of exosomal mRNA as a biomarker in NHL patients.

Plasma Circulating Tumor DNA in Patients with Primary Central Nervous System Lymphoma.

PURPOSE: Analysis of circulating tumor DNA (ctDNA) in blood could allow noninvasive genetic analysis of primary tumors. Although there have been unmet needs for noninvasive methods in patients with primary central nervous system lymphoma (PCNSL), it is still not determined whether plasma ctDNA analysis could be useful for patients with PCNSL. MATERIALS AND METHODS: Targeted deep sequencing of 54 genes was performed in cell-free DNA isolated from plasma samples collected pretreatment, during treatment, and at the end of treatment in 42 consecutively diagnosed PCNSL patients between January 2017 and December 2018. RESULTS: Targeted sequencing of plasma cell-free DNA detected somatic mutations representing ctDNA in 11 cases (11/41, 27%). The detection of ctDNA was not related to the concentration of cell-free DNA or tumor volume. The mutation profiles of these 11 cases varied between patients. The most frequently mutated gene was PIM1 (4/11, 36.4%), whereas KMT2D, PIK3CA, and MYD88 were each observed in three patients (3/11, 27%). The mutations of 13 genes were concordantly found in primary tumor tissue and plasma ctDNA, giving a detection sensitivity of 45%. During the serial tracking of seven patients with complete response, the disappearance of ctDNA mutations was found in four patients, whereas three patients had detected ctDNA mutation at the end of treatment. CONCLUSION: The plasma ctDNA mutation analysis still has limited value for surveillance and predicting treatment outcomes of PCNSL because the detection efficiency was lower than other systemic lymphomas. Thus, analytical platforms should be improved to overcome anatomical hurdles associated with PCNSL.

Single-cell RNA sequencing of human nail unit defines RSPO4 onychofibroblasts and SPINK6 nail epithelium.

Research on human nail tissue has been limited by the restricted access to fresh specimen. Here, we studied transcriptome profiles of human nail units using polydactyly specimens. Single-cell RNAseq with 11,541 cells from 4 extra digits revealed nail-specific mesenchymal and epithelial cell populations, characterized by RSPO4 (major gene in congenital anonychia) and SPINK6, respectively. In situ RNA hybridization demonstrated the localization of RSPO4, MSX1 and WIF1 in onychofibroblasts suggesting the activation of WNT signaling. BMP-5 was also expressed in onychofibroblasts implicating the contribution of BMP signaling. SPINK6 expression distinguished the nail-specific keratinocytes from epidermal keratinocytes. RSPO4+ onychofibroblasts were distributed at close proximity with LGR6+ nail matrix, leading to WNT/ß-catenin activation. In addition, we demonstrated RSPO4 was overexpressed in the fibroblasts of onychomatricoma and LGR6 was highly expressed at the basal layer of the overlying epithelial component, suggesting that onychofibroblasts may play an important role in the pathogenesis of onychomatricoma.

Real-World, Single-Center Data for Lenalidomide Plus Rituximab in Relapsed or Refractory Diffuse Large B-Cell Lymphoma and Transformed Follicular Lymphoma.

BACKGROUND: This study explored the efficacy of lenalidomide plus rituximab for patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) including cases of secondary central nervous system (CNS) involvement and transformed follicular lymphoma (FL) in real-world context because of anti-tumor effect and blood-brain barrier permeability of lenalidomide. METHODS: Twenty-four patients including relapsed or refractory DLBCL (n = 21) including seven patients with secondary CNS involvement and transformed FL (n = 3) were retrospectively analyzed. RESULTS: Based on the best response, the complete response (CR) rate was 21% (5/24) and the overall response rate (ORR) was 38% (9/24). However, as all cases of transformed FL (n = 3) did not respond, all responders had DLBCL, and the CR and ORR rates of DLBCL were 24% (5/21) and 43% (9/21), respectively. The median number of treatment cycles was only two (range: 1-7) due to frequent occurrence of early progression, and 18 patients died and the cause of death was disease progression. The response rate was not significantly different among patients with and without secondary CNS involvement. The median post-treatment overall and progression-free survival were 7.3 and 1.8 months, respectively. Hematologic toxicities were common adverse events, but most hematologic toxicities were manageable. There were no serious infectious complications or treatment-related mortality. CONCLUSION: Lenalidomide plus rituximab might be a salvage therapy for relapsed or refractory DLBCL, especially in case of secondary CNS involvement. However, the addition of other agents should be considered to prolong the duration of response.

Incidence, clinicopathologic, and genetic characteristics of mismatch repair gene-mutated glioblastomas.

BACKGROUND: Glioblastoma (GBM) is the most common and malignant gliomas of adults and recur, resulting in death, despite surgery, radiotherapy, and temozolomide-based chemotherapy. There are a few reports on immunotherapy for the mismatch repair (MMR)-deficient GBMs with high tumor mutational burden (TMB). However, the clinicopathological and genetic features of the MMR genes altered in GBMs have not been elucidated yet. METHODS: The authors analyzed targeted next-generation sequencing (NGS) data from 282 (276 primary and 6 recurrent) glioblastomas to evaluate the mutational status of six DNA repair-related genes: MLH1, MSH2, MSH6, PMS2, POLE, and POLD1. Tumors harboring somatic or germline mutations in one or more of these six genes were classified as an MMR gene-altered GBM. The clinicopathologic and molecular characteristics of MMR gene-altered GBMs were compared to those of tumors without MMR gene alterations. RESULTS: Sixty germline or somatic mutations were identified in 37 cases (35 primary and two recurrent) of GBM. The most frequently mutated genes were MSH6 and POLE. Single nucleotide variants were the most common, followed by frameshift deletions or insertions and approximately 60% of the mutations were germline mutations. Two patients who showed MSH2 (c.2038C > T) and MSH6 (c.1082G > A) mutations had familial colon cancer. The clinical findings were not different between the two groups. However, the presence of MGMT promoter methylation and high tumor mutation burden (TMB) values (> 20) were correlated with MMR gene alterations. CONCLUSION: Since MMR-related genes can be found even in primary glioblastoma and are correlated with high TMB and MGMT promoter methylation, MMR genes should be carefully analyzed in NGS study on glioblastomas.

Multimodal treatments and outcomes for anaplastic thyroid cancer before and after tyrosine kinase inhibitor therapy: a real-world experience.

BACKGROUND: Anaplastic thyroid cancer (ATC) has dismal prognosis and there is no effective treatment. We aimed to evaluate the efficacy of tyrosine kinase inhibitor (TKI) therapy in real-world clinic and to suggest the most effective treatment modality according to the combination of treatments. METHODS: This retrospective study evaluated clinical outcomes and cause of death with multimodal treatments in patients with ATC at Samsung Medical Center. RESULTS: A total of 120 patients received anti-cancer treatment for ATC. Seventy-seven (64.2%) patients underwent surgery, 64 (53.3%) received radiotherapy, 29 (24.2%) received cytotoxic chemotherapy, and 19 (15.8%) received TKI therapy. In the TKI therapy group, eight achieved partial response (three with lenvatinib and five with dabrafenib plus trametinib), and two patients with lenvatinib showed stable disease. Median progression-free survival (PFS) of the TKI therapy group was 2.7 months (range: 0.1-12.7) and their median overall survival (OS) was 12.4 months (range: 1.7-47.7). Patients who received surgery or radiotherapy for local control showed superior OS than those who did not. In a multivariate analysis, surgery, TKI therapy, younger age, and no distant metastasis were associated with favorable OS. The combination of surgery, radiotherapy, and TKI therapy (median OS: 34.3 months, 6-month survival rates: 77.8%) was the most effective. Compared to the era without TKI therapy, distant metastasis has recently become the major cause of death in ATC over airway problems. CONCLUSIONS: Multimodality treatment including TKI therapy demonstrated prolonged survival with dabrafenib plus trametinib as the most effective therapeutic option demonstrated for BRAF mutant ATC patients.

Real-world data on the survival outcome of patients with newly diagnosed Waldenström macroglobulinemia.

BACKGROUND/AIMS: Waldenström macroglobulinemia (WM) is a rare lymphoproliferative disorder that usually follows an indolent clinical course. However, some patients show an aggressive clinical course leading to death. We explored the risk factors predicting poor prognosis in WM patients. METHODS: We retrospectively analyzed 47 patients diagnosed with WM between 2000 and 2018 to explore risk factors predicting poor prognosis using various clinical and laboratory parameters and risk models including the International Prognostic Staging System for WM (IPSS-WM). RESULTS: Over a median follow-up duration of 80.4 months, 29 patients died. The main causes of death were disease progression, organ failure related to amyloidosis, and infection. The median overall survival (OS) was 55.1 months, and 14 patients, including three with amyloidosis, died within 2 years. Serum ß2-microglobulin level higher than 4 mg/dL was significantly associated with poor OS. Accordingly, the IPSS-WM showed a significant association with poor prognosis compared with other risk models, and the low-risk group had better OS than intermediate- and high-risk groups. In the retrospective analysis using the results of targeted sequencing in two cases representing good and bad prognosis, different patterns of mutation profiles were observed, including mutations of MYD88, TP53, ARID1A, and JAK2 in a refractory case. CONCLUSION: Serum ß2-microglobulin could be a single biomarker strongly predictive of poor survival of WM patients, and the low-risk group of the IPSS-WM risk model including serum ß2-microglobulin has better prognostic value than other risk models. Mutation analysis also might provide additional information to predict high-risk patients.

Serum-Derived Exosomal MicroRNA Profiles Can Predict Poor Survival Outcomes in Patients with Extranodal Natural Killer/T-Cell Lymphoma.

Exosomes containing microRNAs (miRNAs) might have utility as biomarkers to predict the risk of treatment failure in extranodal NK/T-cell lymphoma (ENKTL) because exosomal cargo miRNAs could reflect tumor aggressiveness. We analyzed the exosomal miRNAs of patients in favorable (n = 22) and poor outcome (n = 23) groups in a training cohort. Then, using the Nanostring nCounter® microRNA array, we compared them with miRNAs identified in human NK/T lymphoma (NKTL) cell line-derived exosomes to develop exosomal miRNA profiles. We validated the prognostic value of serum exosomal miRNA profiles with an independent cohort (n = 85) and analyzed their association with treatment resistance using etoposide-resistant cell lines. A comparison of the top 20 upregulated miRNAs in the training cohort with poor outcomes with 16 miRNAs that were upregulated in both NKTL cell lines, identified five candidate miRNAs (miR-320e, miR-4454, miR-222-3p, miR-21-5p, and miR-25-3p). Among these, increased levels of exosomal miR-4454, miR-21-5p, and miR-320e were associated with poor overall survival in the validation cohort. Increased levels were also found in relapsed patients post-treatment. These three miRNAs were overexpressed in NKTL cell lines that were resistant to etoposide. Furthermore, transfection of NKTL cell lines with miR-21-5p and miR-320e induced an increase in expression of the proinflammatory cytokines such as macrophage inflammatory protein 1 alpha. These studies show that serum levels of exosomal miR-21-5p, miR-320e, and miR-4454 are increased in ENKTL patients with poor prognosis. Upregulation of these exosomal miRNAs in treatment-resistant cell lines suggests they have a role as biomarkers for the identification of ENKTL patients at high risk of treatment failure.

Clinical advantage of targeted sequencing for unbiased tumor mutational burden estimation in samples with low tumor purity.

BACKGROUND: Tumor mutational burden (TMB) measurement is limited by low tumor purity of samples, which can influence prediction of the immunotherapy response, particularly when using whole-exome sequencing-based TMB (wTMB). This issue could be overcome by targeted panel sequencing-based TMB (pTMB) with higher depth of coverage, which remains unexplored. METHODS: We comprehensively reanalyzed four public datasets of immune checkpoint inhibitor (ICI)-treated cohorts (adopting pTMB or wTMB) to test each biomarker's predictive ability for low purity samples (cut-off: 30%). For validation, paired genomic profiling with the same tumor specimens was performed to directly compare wTMB and pTMB in patients with breast cancer (paired-BRCA, n=165) and ICI-treated patients with advanced non-small-cell lung cancer (paired-NSCLC, n=156). RESULTS: Low tumor purity was common (range 30%-45%) in real-world samples from ICI-treated patients. In the survival analyzes of public cohorts, wTMB could not predict the clinical benefit of immunotherapy when tumor purity was low (log-rank p=0.874), whereas pTMB could effectively stratify the survival outcome (log-rank p=0.020). In the paired-BRCA and paired-NSCLC cohorts, pTMB was less affected by tumor purity, with significantly more somatic variants identified at low allele frequency (p<0.001). We found that wTMB was significantly underestimated in low purity samples with a large proportion of clonal variants undetected by whole-exome sequencing. Interestingly, pTMB more accurately predicted progression-free survival (PFS) after immunotherapy than wTMB owing to its superior performance in the low tumor purity subgroup (p=0.054 vs p=0.358). Multivariate analysis revealed pTMB (p=0.016), but not wTMB (p=0.32), as an independent predictor of PFS even in low-purity samples. The net reclassification index using pTMB was 21.7% in the low-purity subgroup (p=0.016). CONCLUSIONS: Our data suggest that TMB characterization with targeted deep sequencing might have potential strength in predicting ICI responsiveness due to its enhanced sensitivity for hard-to-detect variants at low-allele fraction. Therefore, pTMB could act as an invaluable biomarker in the setting of both clinical trials and practice outside of trials based on its reliable performance in mitigating the purity-related bias.

Characteristics and Clinical Outcomes of Non-small Cell Lung Cancer Patients in Korea With MET Exon 14 Skipping.

BACKGROUND/AIM: MET exon 14 skipping occurs in 3-4% of patients with lung adenocarcinomas. In this study, we performed a comprehensive analysis of clinical data from Korean non-small cell lung cancer (NSCLC) patients with MET exon 14 skipping. PATIENTS AND METHODS: Overall, 1,020 patients diagnosed with NSCLC between January 2015 and July 2017 were analyzed by next-generation sequencing. RESULTS: MET exon 14 skipping was identified in 20 NSCLC patients (1.9%). The median age was 69 years (range=39-86 years), 60.0% were male, and most (55.0%) were ever-smokers. For first-line chemotherapy, the median overall survival was 9.5 months and progression-free survival was 4.0 months, respectively. Twelve patients received pemetrexed-based chemotherapy and the overall response rate was 33.3% (4/12). Among four crizotinib-treated patients, one continued therapy for 8 months with the best response being disease stability. CONCLUSION: Given the poor clinical outcome and response to therapy for NSCLC, and the availability of promising anti-tumor MET inhibitors, screening for the MET exon 14 skip mutation should be incorporated into clinical practice.

Characteristics and outcomes of RET-rearranged Korean non-small cell lung cancer patients in real-world practice.

OBJECTIVE: Since the first discovery of rearranged during transfection (RET) fusion in lung adenocarcinoma in 2011, two tyrosine kinase inhibitors, namely vandetanib and cabozantinib, are currently available. Despite favorable outcomes in systemic control, the intracranial therapeutic response remains insufficient. In this study, the clinical characteristics and outcomes of non-small cell lung cancer (NSCLC) patients with RET rearrangements were analyzed. METHODS: Patients with NSCLC harboring RET fusion who received treatment between January 2006 and January 2018 were analyzed. RET rearrangement was identified by FISH or NGS. RESULTS: A total of 59 patients were identified. About half of the patients were female (47.5%) and never smokers (50.9%). Most patients had adenocarcinoma (89.8%). A total of 17 patients (28.8%) had an intracranial lesion at the initial diagnosis of stage IV disease, and 11 additional patients (18.6%) developed intracranial metastases during follow-up. The median time to development of intracranial metastases was 19.0 months (95% CI: 9.6-28.5), resulting in a >60% cumulative incidence of brain metastasis at 24 months. The systemic efficacy of pemetrexed-based regimens was favorable with progression-free survival of 9.0 (95% CI: 6.9-11.2) and OS of 24.1 (95% CI: 15.2-33.0) months. The median progression-free survival for vandetanib and immunotherapy was 2.9 (95% CI: 2.0-3.8) and 2.1 (95% CI: 1.6-2.6) months, respectively. CONCLUSIONS: Given the likelihood of RET-rearranged NSCLC progressing to intracranial metastases and the absence of apparent clinical benefit of currently available targeted or immunotherapeutic agents, development of novel treatment with higher selectivity and better penetration of the blood-brain barrier remains a priority.

Paired genomic analysis of squamous cell carcinoma transformed from EGFR-mutated lung adenocarcinoma.

OBJECTIVES: Adenocarcinoma (ADC) to squamous cell carcinoma (SCC) transformation (AST) is reported in epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer after tyrosine kinase inhibitor (TKI) failure. However, little is known about the underlying genomic changes during the AST process. MATERIALS AND METHODS: We retrospectively reviewed our tissue database collected after first- or second- generation EGFR TKI resistance (n = 263) and identified 3 cases of AST. The additional case was acquired from the osimertinib resistance sample. Deep target sequencing (381 genes) using paired samples from 4 patients with AST after EGFR TKI treatment was performed. The histology of each sample was confirmed by TTF-1 and p63 immunohistochemistry. The patients received first- or second-generation EGFR TKI as an initial treatment. RESULTS: Overall incidence of AST was 1.1% (3/263). Transformed SCC acquired genomic alterations related to the PI3K/AKT/mTOR pathway, in addition to the initial EGFR mutation. In a representative case, two separate sub-clones, with a PTEN nonsense mutation and EGFR p.T790 M mutation, were observed without histologic transformation at the time of gefitinib resistance. After subsequent treatment with osimertinib, SCC transformation was observed with the disappearance of the EGFR p.T790 M mutation and acquired copy number loss in PTEN. Adopting the sub-clonal fraction model elucidates the sub-clonal evolution process of the PTEN mutant sub-clone toward AST under the background of EGFR mutation. The rest of the transformed samples also had acquired genomic alterations in PTEN, LKB1, PIK3CA, or RICTOR, which are related to the PI3K/AKT/mTOR pathway. CONCLUSIONS: Paired genomic analysis from our sample provides early clinical evidence of the ADC to SCC lineage transition that might be provoked by an alteration in the PI3K/AKT/mTOR pathway during EGFR TKI treatment. This finding could potentially broaden the known spectrum of EGFR TKI resistance mechanisms.

Landscape of Actionable Genetic Alterations Profiled from 1,071 Tumor Samples in Korean Cancer Patients.

PURPOSE: With the emergence of next-generation sequencing (NGS) technology, profiling a wide range of genomic alterations has become a possibility resulting in improved implementation of targeted cancer therapy. In Asian populations, the prevalence and spectrum of clinically actionable genetic alterations has not yet been determined because of a lack of studies examining high-throughput cancer genomic data. MATERIALS AND METHODS: To address this issue, 1,071 tumor samples were collected from five major cancer institutes in Korea and analyzed using targeted NGS at a centralized laboratory. Samples were either fresh frozen or formalin-fixed, paraffin embedded (FFPE) and the quality and yield of extracted genomic DNA was assessed. In order to estimate the effect of sample condition on the quality of sequencing results, tissue preparation method, specimen type (resected or biopsied) and tissue storage time were compared. RESULTS: We detected 7,360 non-synonymous point mutations, 1,164 small insertions and deletions, 3,173 copy number alterations, and 462 structural variants. Fifty-four percent of tumors had one or more clinically relevant genetic mutation. The distribution of actionable variants was variable among different genes. Fresh frozen tissues, surgically resected specimens, and recently obtained specimens generated superior sequencing results over FFPE tissues, biopsied specimens, and tissues with long storage duration. CONCLUSION: In order to overcome, challenges involved in bringing NGS testing into routine clinical use, a centralized laboratory model was designed that could improve the NGS workflows, provide appropriate turnaround times and control costs with goal of enabling precision medicine.

Rare Mechanism of Acquired Resistance to Osimertinib in Korean Patients with EGFR-mutated Non-small Cell Lung Cancer.

Epidermal growth factor receptor (EGFR)‒tyrosine kinase inhibitors (TKIs) are effective clinical therapeutics for EGFR-mutant non-small cell lung cancer (NSCLC). Osimertinib, a thirdgeneration EGFR TKI, has proven effective against T790M mutations. However, the vast majority of patients acquire resistance following successful treatment. A 59-year-old female patient with metastatic NSCLC developed resistance after 43 weeks of osimertinib. CancerSCAN of the metastatic liver lesion revealed a EGFR C797G mutation at an allele frequency of 72%, a preexisting T790M mutation (73%) in cis and an exon 19 deletion (87%). Another 53-year-old female patient developed systemic progression after 10 months of osimertinib. CancerSCAN of the lung biopsy identified an EGFR L718Q mutation at an allele frequency of 7%, concomitant PIK3CA E545K (12.90%) and preexisting EGFR L858R (38%), but loss of the T790M mutation. The heterogeneity of osimertinib resistance mechanisms warrants further investigation into novel or combination agents to overcome the rare acquired resistances.

Concurrent Genetic Alterations Predict the Progression to Target Therapy in EGFR-Mutated Advanced NSCLC.

INTRODUCTION: EGFR-mutant NSCLC displays diverse outcomes to tyrosine kinase inhibitor (TKI) treatment. Because co-occurring genomic alterations might describe different biological subsets of patients with this cancer, exploring co-occurring genomic alterations that impact patients' outcomes using a comprehensive gene panel is potentially important. METHODS: This retrospective cohort study was conducted with the panel-sequencing data acquired from January 2014 to May 2017, and clinical outcome data collected until February 2018. This study includes all eligible patients who possess panel-sequencing data before treatment with first-/second-generation EGFR-TKIs (cohort 1) or third-generation EGFR-TKIs following initial EGFR-TKI failure (cohort 2). RESULTS: Seventy-five patients (mean [SD] age, 58.5 [11.0] years; 68.0% women) were included in cohort 1, and 82 patients (mean [SD] age, 57.3 [9.1] years; 67.1% women) were included in cohort 2. In cohort 1, alterations in TP53 were independently associated with worse progression-free survival (PFS) (hazard ratio [HR]: 2.02; 95% confidence interval [CI]: 1.04-3.93; p = 0.038) in multivariate analysis. In cohort 2, TP53 mutation was associated with significantly worse PFS (8.9 versus 12.8 months; p = 0.029). RB1 mutation was significantly associated with worse (median PFS, 1.9 versus 11.7 months; p < 0.001). PTEN mutation was associated with significantly worse PFS (2.6 versus 10.3 months; p = 0.001). MDM2 amplification was associated with worse PFS (6.6 versus 10.4 months; p = 0.025). In cohort 2, multivariate analysis revealed that alterations in TP53 (HR: 2.23; 95% CI: 1.16-4.29; p = 0.017), RB1 (HR: 5.62; 95% CI: 1.96-16.13; p = 0.001), PTEN (HR: 5.84; 95% CI: 1.56-21.85; p = 0.009), and MDM2 (HR: 2.46; 95% CI: 1.02-5.94; p = 0.046) were independently associated with worse PFS. CONCLUSIONS: Co-occurring genomic alterations detected by panel sequencing are associated with the clinical outcomes of EGFR-TKI treatment in NSCLC.

Clinical Relevance of Genomic Changes in Recurrent Pediatric Solid Tumors.

PURPOSE: Relapsed/refractory pediatric cancers show poor prognosis; however, their genomic patterns remain unknown. To investigate the genetic mechanisms of tumor relapse and therapy resistance, we characterized genomic alterations in diagnostic and relapsed lesions in patients with relapsed/refractory pediatric solid tumors using targeted deep sequencing. PATIENTS AND METHODS: A targeted sequencing panel covering the exons of 381 cancer genes was used to characterize 19 paired diagnostic and relapsed samples from patients with relapsed/refractory pediatric solid tumors. RESULTS: The mean coverage for all samples was 930.6× (SD = 213.8). Among the 381 genes, 173 single nucleotide variations (SNVs)/insertion-deletions (InDels), 100 copy number alterations, and 1 structural variation were detected. A total of 72.6% of SNVs in primary tumors were also found in recurrent lesions, and 27.2% of SNVs in recurrent tumors had newly occurred. Among SNVs/InDels detected only in recurrent lesions, 71% had a low variant allele fraction (<10%). Patients were classified into three categories based on the mutation patterns after cancer treatment. A significant association between the major mutation patterns and clinical outcome was observed. Patients whose relapsed tumor had fewer mutations than the diagnostic sample tended to be older, had longer progression-free survival, and achieved complete remission after relapse. Contrastingly, patients whose genetic profile only had concordant mutations without any change had the worst outcome. CONCLUSIONS: We characterized genomic changes in recurrent pediatric solid tumors. These findings could help to understand the biology of relapsed childhood cancer and to develop personalized treatment based on their genetic profile.

Mutational profiling of acral melanomas in Korean populations.

The proportion of acral melanoma (AM) is much higher in Asian populations than in Caucasian populations. Although mutational profiles associated with AM have been discovered in Caucasian populations, knowledge of its genetic alterations in Asian populations is limited. To describe the molecular nature of AM in Korean patients, we performed mutational profiling of AM and matched normal tissues in patients. Fifty-one formalin-fixed paraffin-embedded AM samples and 32 matched pairs from patients' saliva DNA were analysed by next-generation sequencing. Only mutations confirmed via digital droplet PCR or in BRAF, KIT and NRAS, the most frequently altered cancer genes in cutaneous melanoma, were considered as positive. The relationship between mutational status and clinicopathological features were examined. Of the 47 AM patients screened, alteration of BRAF, NRAS and KIT genes was observed in 6.4%, 4.3% and 8.5%, respectively. We also tested matched normal tissues of patients to identify tumor-specific mutations. Examination of the mutational profile in a cohort of 28 primary melanomas and matched normal controls found BRAF mutations in two cases (7.1%), KIT mutations in three cases (10.7%) and CTNNB1 mutations in one case (3.6%). The BRAF, NRAS and KIT mutation status did not correlate with clinicopathological characteristics. Our results show that KIT, NRAS and BRAF hotspot mutations occur at a low frequency in Korean populations. We also observed a case with the CTNNB1 mutation, which raises the possibility that other pathways are associated with AM development.