Prevalence and clinical association of gene mutations through multiplex mutation testing in patients with NSCLC: results from the ETOP Lungscape Project.

Background: Reported prevalence of driver gene mutations in non-small-cell lung cancer (NSCLC) is highly variable and clinical correlations are emerging. Using NSCLC biomaterial and clinical data from the European Thoracic Oncology Platform Lungscape iBiobank, we explore the epidemiology of mutations and association to clinicopathologic features and patient outcome (relapse-free survival, time-to-relapse, overall survival). Methods: Clinically annotated, resected stage I-III NSCLC FFPE tissue was assessed for gene mutation using a microfluidics-based multiplex PCR platform. Mutant-allele detection sensitivity is >1% for most of the ∼150 (13 genes) mutations covered in the multiplex test. Results: Multiplex testing has been carried out in 2063 (76.2%) of the 2709 Lungscape cases (median follow-up 4.8 years). FFPE samples mostly date from 2005 to 2008, yet recently extracted DNA quality and quantity was generally good. Average DNA yield/case was 2.63 µg; 38 cases (1.4%) failed QC and were excluded from study; 95.1% of included cases allowed the complete panel of mutations to be tested. Most common were KRAS, MET, EGFR and PIK3CA mutations with overall prevalence of 23.0%, 6.8%, 5.4% and 4.9%, respectively. KRAS and EGFR mutations were significantly more frequent in adenocarcinomas: PIK3CA in squamous cell carcinomas. MET mutation prevalence did not differ between histology groups. EGFR mutations were found predominantly in never smokers; KRAS in current/former smokers. For all the above mutations, there was no difference in outcome between mutated and non-mutated cases. Conclusion: Archival FFPE NSCLC material is adequate for multiplex mutation analysis. In this large, predominantly European, clinically annotated stage I-III NSCLC cohort, none of the mutations characterized showed prognostic significance.

Role of proton-coupled folate transporter in pemetrexed resistance of mesothelioma: clinical evidence and new pharmacological tools.

BACKGROUND: Thymidylate synthase (TS) has a predictive role in pemetrexed treatment of mesothelioma; however, additional chemoresistance mechanisms are poorly understood. Here, we explored the role of the reduced-folate carrier (RFC/SLC19A1) and proton-coupled folate transporter (PCFT/SLC46A1) in antifolate resistance in mesothelioma. PATIENTS AND METHODS: PCFT, RFC and TS RNA and PCFT protein levels were determined by quantitative RT-PCR of frozen tissues and immunohistochemistry of tissue-microarrays, respectively, in two cohorts of pemetrexed-treated patients. Data were analyzed by t-test, Fisher's/log-rank test and Cox proportional models. The contribution of PCFT expression and PCFT-promoter methylation to pemetrexed activity were evaluated in mesothelioma cells and spheroids, through 5-aza-2'-deoxycytidine-mediated demethylation and siRNA-knockdown. RESULTS: Pemetrexed-treated patients with low PCFT had significantly lower rates of disease control, and shorter overall survival (OS), in both the test (N = 73, 11.3 versus 20.1 months, P = 0.01) and validation (N = 51, 12.6 versus 30.3 months, P = 0.02) cohorts. Multivariate analysis confirmed PCFT-independent prognostic role. Low-PCFT protein levels were also associated with shorter OS. Patients with both low-PCFT and high-TS levels had the worst prognosis (OS, 5.5 months), whereas associations were neither found for RFC nor in pemetrexed-untreated patients. PCFT silencing reduced pemetrexed sensitivity, whereas 5-aza-2'-deoxycytidine overcame resistance. CONCLUSIONS: These findings identify for the first time PCFT as a novel mesothelioma prognostic biomarker, prompting prospective trials for its validation. Moreover, preclinical data suggest that targeting PCFT-promoter methylation might eradicate pemetrexed-resistant cells characterized by low-PCFT expression.

Non-classic EGFR mutations in a cohort of Dutch EGFR-mutated NSCLC patients and outcomes following EGFR-TKI treatment.

BACKGROUND: Data on non-small-cell lung cancer (NSCLC) patients with non-classic epidermal growth factor receptor (EGFR) mutations are scarce, especially in non-Asian populations. The purpose of this study was to evaluate prevalence, clinical characteristics and outcome on EGFR-TKI treatment according to type of EGFR mutation in a Dutch cohort of NSCLC patients. METHODS: We retrospectively evaluated a cohort of 240 EGFR-mutated NSCLC patients. Data on demographics, clinical and tumour-related features, EGFR-TKI treatment and clinical outcome were collected and compared between patients with classic EGFR mutations, EGFR exon 20 insertions and other uncommon EGFR mutations. RESULTS: Classic EGFR mutations were detected in 186 patients (77.5%) and non-classic EGFR mutations in 54 patients (22.5%); 23 patients with an exon 20 insertion (9.6%) and 31 patients with an uncommon EGFR mutation (12.9%). Median progression-free survival (PFS) and overall survival (OS) on EGFR-TKI treatment were 2.9 and 9.7 months, respectively, for patients with an EGFR exon 20 insertion, and 6.4 and 20.2 months, respectively, for patients with an uncommon EGFR mutation. Patients with a double uncommon EGFR mutation that included G719X/L861Q/S768I had longer PFS and OS on EGFR-TKI treatment compared with patients with a single G719X/L861Q/S768I EGFR mutation (both P=0.02). CONCLUSIONS: In our Dutch cohort, prevalence and genotype distribution of non-classic EGFR mutations were in accordance with previously reported data. The PFS and OS on EGFR-TKI treatment in patients with an uncommon EGFR mutation were shorter compared with patients with classic EGFR mutations, but varied among different uncommon EGFR mutations.

DNA hypermethylation analysis in sputum for the diagnosis of lung cancer: training validation set approach.

BACKGROUND: Lung cancer has the highest mortality of all cancers. The aim of this study was to examine DNA hypermethylation in sputum and validate its diagnostic accuracy for lung cancer. METHODS: DNA hypermethylation of RASSF1A, APC, cytoglobin, 3OST2, PRDM14, FAM19A4 and PHACTR3 was analysed in sputum samples from symptomatic lung cancer patients and controls (learning set: 73 cases, 86 controls; validation set: 159 cases, 154 controls) by quantitative methylation-specific PCR. Three statistical models were used: (i) cutoff based on Youden's J index, (ii) cutoff based on fixed specificity per marker of 96% and (iii) risk classification of post-test probabilities. RESULTS: In the learning set, approach (i) showed that RASSF1A was best able to distinguish cases from controls (sensitivity 42.5%, specificity 96.5%). RASSF1A, 3OST2 and PRDM14 combined demonstrated a sensitivity of 82.2% with a specificity of 66.3%. Approach (ii) yielded a combination rule of RASSF1A, 3OST2 and PHACTR3 (sensitivity 67.1%, specificity 89.5%). The risk model (approach iii) distributed the cases over all risk categories. All methods displayed similar and consistent results in the validation set. CONCLUSIONS: Our findings underscore the impact of DNA methylation markers in symptomatic lung cancer diagnosis. RASSF1A is validated as diagnostic marker in lung cancer.

Assessing standardization of molecular testing for non-small-cell lung cancer: results of a worldwide external quality assessment (EQA) scheme for EGFR mutation testing.

BACKGROUND: The external quality assurance (EQA) process aims at establishing laboratory performance levels. Leading European groups in the fields of EQA, Pathology, and Medical and Thoracic Oncology collaborated in a pilot EQA scheme for somatic epidermal growth factor receptor (EGFR) gene mutational analysis in non-small-cell lung cancer (NSCLC). METHODS: EQA samples generated from cell lines mimicking clinical samples were provided to participating laboratories, each with a mock clinical case. Participating laboratories performed the analysis using their usual method(s). Anonymous results were assessed and made available to all participants. Two subsequent EQA rounds followed the pilot scheme. RESULTS: One hundred and seventeen labs from 30 countries registered and 91 returned results. Sanger sequencing and a commercial kit were the main methodologies used. The standard of genotyping was suboptimal, with a significant number of genotyping errors made. Only 72 out of 91 (72%) participants passed the EQA. False-negative and -positive results were the main sources of error. The quality of reports submitted was acceptable; most were clear, concise and easy to read. However, some participants reported the genotyping result in the absence of any interpretation and many obscured the interpretation required for clinical care. CONCLUSIONS: Even in clinical laboratories, the technical performance of genotyping in EGFR mutation testing for NSCLC can be improved, evident from a high level of diagnostic errors. Robust EQA can contribute to global optimisation of EGFR testing for NSCLC patients.

Semiautomated volumetric response evaluation as an imaging biomarker in superior sulcus tumors.

BACKGROUND: Volumetric response to therapy has been suggested as a biomarker for patient-centered outcomes. The primary aim of this pilot study was to investigate whether the volumetric response to induction chemoradiotherapy was associated with pathological complete response (pCR) or survival in patients with superior sulcus tumors managed with trimodality therapy. The secondary aim was to evaluate a semiautomated method for serial volume assessment. METHODS: In this retrospective study, treatment outcomes were obtained from a departmental database. The tumor was delineated on the computed tomography (CT) scan used for radiotherapy planning, which was typically performed during the first cycle of chemotherapy. These contours were transferred to the post-chemoradiotherapy diagnostic CT scan using deformable image registration (DIR) with/without manual editing. RESULTS: CT scans from 30 eligible patients were analyzed. Median follow-up was 51 months. Neither absolute nor relative reduction in tumor volume following chemoradiotherapy correlated with pCR or 2-year survival. The tumor volumes determined by DIR alone and DIR + manual editing correlated to a high degree (R(2) = 0.99, P < 0.01). CONCLUSION: Volumetric response to induction chemoradiotherapy was not correlated with pCR or survival in patients with superior sulcus tumors managed with trimodality therapy. DIR-based contour propagation merits further evaluation as a tool for serial volumetric assessment.

Lung cysts as indicator for Birt-Hogg-Dubé syndrome.

In this case, we describe a patient with a history of recurrent pneumothorax. Based on CT-thorax and histopathology of the lung tissue, the Birt-Hogg-Dubé syndrome was suspected and confirmed after genetic testing. Recognizing this syndrome by pulmonologists and radiologists is very important, because the risk on developing of renal cell cancer is high.

Molecular sputum analysis for the diagnosis of lung cancer.

Lung cancer is the leading cause of cancer mortality rate worldwide, mainly because of the presence of metastatic disease at the time of diagnosis. Early detection of lung cancer improves prognosis, and towards this end, large screening trials in high-risk individuals have been conducted since the past century. Despite all efforts, the need for novel (complementary) lung cancer diagnostic and screening methods still exists. In this review, we focus on the assessment of lung cancer-related biomarkers in sputum in the past decennium. Besides cytology, mutation and microRNA analysis, special attention has been paid to DNA promoter hypermethylation, of which all available literature is summarised without time restriction. A model is proposed to aid in the distinction between diagnostic and risk markers. Research on the use of sputum for non-invasive detection of early-stage lung cancer has brought new insights and advanced molecular techniques. The sputum shows a promising potential for routine diagnostic and possibly screening purposes.

Surprising impact of stromal TIL's on immunotherapy efficacy in a real-world lung cancer study.

INTRODUCTION: Immune checkpoint inhibitors (ICI), such as anti-PD-1 agents, have become part of the standard of care treatment of advanced non-small cell lung cancer (NSCLC). Predictive biomarkers are needed to identify patients that benefit from anti-PD-1 treatments. Tumor infiltrating lymphocytes (TILs) and PD-L1 are major players in the ICI mechanism of action. In this study, we assess the impact of real-world clinicopathological variables, including TILs and PD-L1, on anti-PD-1 efficacy. METHODS: We performed a monocenter retrospective study in advanced NSCLC treated with nivolumab or pembrolizumab between January 2015 and February 2019. The impact of baseline clinical and pathological variables was assessed by univariate and multivariate models. TILs, defined as CD8+T-cells, and PD-L1 were scored in tumor and stroma, and correlated with progression free survival (PFS) and overall survival (OS). RESULTS: We included 366 patients of whom 141 were assessed for tumor and stromal TILs. The median follow-up time was 487 days. In the whole cohort, PFS was associated with high tumor PD-L1, high albumin and good performance. OS was associated with low LDH, high albumin, good performance and 'first-line treatment'. In the TILs subcohort, stromal TILs had the strongest impact on PFS and OS. Stromal TILs were a stronger marker for PFS and OS than tumoral TILs, tumoral PD-L1 or stromal PD-L1. Remaining factors for PFS and OS were albumin and albumin with LDH, respectively. CONCLUSIONS: This real-world study on clinicopathological features shows that stromal CD8 + TILs were the strongest predictor for PFS and OS in patients with advanced NSCLC on anti-PD-1 therapy. Other predictors for PFS and OS included albumin and albumin together with LDH, respectively. This study highlights the pivotal role of the stromal compartment in the mechanisms of action of ICI, and the need for further studies aiming to overcome this stromal firewall.

DLL3 expression in large cell neuroendocrine carcinoma (LCNEC) and association with molecular subtypes and neuroendocrine profile.

OBJECTIVES: For stage IV pulmonary large cell neuroendocrine carcinoma (LCNEC), the only therapeutic option is palliative chemotherapy. DLL3 is a new therapeutic target, which seems to be often expressed in SCLC and LCNEC. It has recently been reported that DLL3 mRNA expression is particularly upregulated in the LCNEC subgroup with STK11/KEAP1 and TP53 co-mutations, in contrast to lower expression levels in RB1 and TP53 co-mutated LCNEC. Our aim was to investigate DLL3 protein expression in stage IV LCNEC and correlate data with mutational profiles (i.e.STK11/KEAP1/RB1), immunostaining results (pRb, NE markers) and clinical characteristics. MATERIALS AND METHODS: Immunohistochemical analysis for DLL3 (SC16.65) and ASCL1 (SC72.201) was performed on 94 and 51 FFPE tissue sections, respectively, of pathologically reviewed stage IV LCNEC. DLL3 and ASCL1 were scored positive if ≥1% of the tumor cells showed cytoplasmic/membranous or dotlike (DLL3) or nuclear (ASCL1) immunostaining. Data were correlated with available sequencing (TP53, RB1, STK11, KEAP1), immunostaining (pRb, NE markers) and clinical data. RESULTS: DLL3 was expressed in 70/94 (74%) LCNEC, 56 (80%) of which showed cytoplasmic/membranous staining. Median H-score was 55 (interquartile range 0-160). DLL3 staining was not different in pRb immunohistochemistry negative and positive patients (DLL3+ in 53/70 (76%) vs. 14/21 (67%), p = 0.409) or RB1 mutated and wildtype patients (DLL3+ in 27/34 (79%) vs. 23/33 (70%), p = 0.361). Nevertheless, 6/6 (100%) STK11 mutated, 10/11 (91%) KEAP1 mutated and 9/9 (100%) TP53 wildtype tumors were DLL3+ . Furthermore, DLL3 expression was associated with expression of ASCL1 and at least 2 out of 3 neuroendocrine markers. CONCLUSION: The high percentage (74%) of DLL3 expression in stage IV LCNEC denotes the potential of DLL3 targeted therapy in this patient group.

Prevalence and prognostic value of PD-L1 expression in molecular subtypes of metastatic large cell neuroendocrine carcinoma (LCNEC).

BACKGROUND: Pulmonary large cell neuroendocrine carcinoma (LCNEC) is a rare tumor with high mutational burden. Two subtypes of LCNEC are recognized, the co-mutated TP53 and RB1 group and the TP53 and STK11/KEAP1 group. We investigated PD-L1 and CD8 expression in a well characterized stage IV LCNEC cohort and compared expression in the two subtypes. METHODS: Immunohistochemical (IHC) analysis for PD-L1 and CD8 was performed on pathological reviewed pretreatment tumor samples for 148 stage IV LCNEC. Data about targeted next generation sequencing (TNGS) (TP53, RB1, STK11, KEAP1) and IHC for RB1 were available for most tumors. IHC staining for PD-L1 (DAKO 28-8) was performed and scored positive if tumors showed ≥1% membranous staining. CD8 was scored for intra-tumor T-cells and stromal cells. RESULTS: PD-L1 IHC expression data could be generated in 98/148 confirmed LCNEC samples along with RB1 IHC (n = 97) of which 77 passed quality control for TNGS. PD-L1 expression was positive in 16/98 cases (16%); 5 (5%) with ≥50%. PD-L1 expression was equal in RB1 mutated and RB1 wildtype tumors. None of STK11 mutated tumors (n = 7) expressed PD-L1. PD-L1 expression was correlated with superior overall survival (OS), hazard ratio 0.55 ((95% Confidence Interval 0.31-0.96), p = 0.038). Intra-tumor CD8 was associated with PD-L1 expression (p = 0.021) and stromal and intra-tumor CD8 were correlated with improved OS (p = 0.037 and p = 0.026 respectively). CONCLUSIONS: PD-L1 expression was positive in 16% of stage IV LCNEC tumors. This was independent of molecular subtype but associated with CD8 expression. In LCNEC patients with PD-L1 and/or CD8 expression superior OS was observed.

ALK immunohistochemistry positive, FISH negative NSCLC is infrequent, but associated with impaired survival following treatment with crizotinib.

OBJECTIVE: Metastasized non-small cell lung cancer (NSCLC) with an anaplastic lymphoma kinase (ALK) rearrangement is usually sensitive to a range of ALK-tyrosine kinase inhibitors. ALK-positive NSCLC have been identified in pivotal phase III trials with fluorescence in situ hybridization (ALK FISH+). These tumors are also expressing the fusion product (ALK immunohistochemistry (IHC)+). However, discrepant cases occur, including ALK IHC + FISH-. The aim of this study was to collect ALK IHC + cases and compare within this group response to crizotinib treatment of ALK FISH + cases with ALK FISH- cases. MATERIALS AND METHODS: In this European prospective multicenter research study patients with Stage IV ALK IHC + NSCLC treated with crizotinib were enrolled. Tumor slides were validated centrally for ALK IHC and ALK FISH. RESULTS: Registration of 3523 ALK IHC tests revealed a prevalence of 2.7% (n = 94) ALK IHC + cases. Local ALK FISH analysis resulted in 48 concordant (ALK IHC+/FISH+) and 16 discordant (ALK IHC+/FISH-) cases. Central validation revealed 37 concordant and 7 discordant cases, 5 of which had follow-up. Validation was hampered by limited amount of tissue in biopsy samples. The PFS at 1 year for ALK concordant and discordant was 58% and 20%, respectively (HR = 2.4; 95% CI: 0.78-7.3; p = 0.11). Overall survival was significantly better for concordant cases than discordant cases after central validation (HR=4.5; 95% CI= 1.2-15.9; p=0.010. CONCLUSION: ALK IHC + FISH- NSCLC is infrequent and associated with a worse outcome on personalized treatment. A suitable predictive testing strategy may be to screen first with IHC and then confirm with FISH instead of considering ALK IHC equivalent to ALK FISH according to the current guidelines.

Whole body PD-1 and PD-L1 positron emission tomography in patients with non-small-cell lung cancer.

PD-L1 immunohistochemistry correlates only moderately with patient survival and response to PD-(L)1 treatment. Heterogeneity of tumor PD-L1 expression might limit the predictive value of small biopsies. Here we show that tumor PD-L1 and PD-1 expression can be quantified non-invasively using PET-CT in patients with non-small-cell lung cancer. Whole body PD-(L)1 PET-CT reveals significant tumor tracer uptake heterogeneity both between patients, as well as within patients between different tumor lesions.

Overall survival in EGFR mutated non-small-cell lung cancer patients treated with afatinib after EGFR TKI and resistant mechanisms upon disease progression.

PURPOSE: To determine survival in afatinib-treated patients after treatment with first-generation EGFR tyrosine kinase inhibitors (TKIs) and to study resistance mechanisms in afatinib-resistant tumors. METHODS: Characteristics and survival of patients treated with afatinib after resistance to erlotinib or gefitinib in two large Dutch centers were collected. Whole exome sequencing (WES) and pathway analysis was performed on available pre- and post-afatinib tumor biopsies and normal tissue. RESULTS: A total of 38 patients were treated with afatinib. T790M mutations were identified in 22/29 (76%) pre-afatinib treatment tumor samples. No difference in median progression-free-survival (2.8 months (95% CI 2.3-3.3) and 2.7 months (95% CI 0.9-4.6), p = 0.55) and median overall-survival (8.8 months (95% CI 4.2-13.4) and 3.6 months (95% CI 2.3-5.0), p = 0.14) were observed in T790M+ patients compared to T790M- mutations. Somatic mutations in TP53, ADAMTS2, CNN2 and multiple genes in the Wnt and PI3K-AKT pathway were observed in post-afatinib tumors of six afatinib-responding and in one non-responding patient. No new EGFR mutations were found in the post-afatinib samples of the six responding patients. Further analyses of post-afatinib progressive tumors revealed 28 resistant specific mutations in six genes (HLA-DRB1, AQP7, FAM198A, SEC31A, CNTLN, and ESX1) in three afatinib responding patients. No known EGFR-TKI resistant-associated copy number gains were acquired in the post-afatinib samples. CONCLUSION: No differences in survival were observed in patients with EGFR-T790M treated with afatinib compared to those without T790M. Tumors from patients who had progressive disease during afatinib treatment were enriched for mutations in genes involved in Wnt and PI3K-AKT pathways.

Effectiveness of crizotinib in a patient with ALK IHC-positive/FISH-negative metastatic lung adenocarcinoma.

We report a case of crizotinib effectiveness in a heavily pretreated patient with a metastatic NSCLC initially considered IHC-positive and FISH-negative for ALK rearrangement. After repeated analyses of tumor samples, borderline ALK FISH-positivity (18.5% positive cells) was demonstrated.

Cell proliferation and apoptosis in stage III inoperable non-small cell lung carcinoma treated by radiotherapy.

PURPOSE: The purpose of this study was to assess the prognostic value of the expression of p53 and bcl-2, the apoptotic index and the expression of topoisomerase II alpha in patients with inoperable non-small cell lung cancer (NSCLC) treated with high dose radiotherapy. PATIENTS AND METHODS: A number of 161 patients with inoperable NSCLC treated with high dose radiotherapy (60 Gy) were included. Immunohistochemical analysis was used to assess the expression of nuclear p53-protein, topoisomerase II alpha and cytoplasmatic expression of bcl-2, while spontaneous apoptosis was assessed using in situ labeling. The minimal follow up period was 2 years. RESULTS: Local control did not only depend on the presence of p53 expression, but also on the proportion of p53 positive cells. The most important prognostic factor was the apoptotic index. A high apoptotic index was associated with worse local control, more distant metastases and a significantly worse overall survival. No association was noted between the expression of bcl-2 and topoisomerase II alpha with any of the endpoints. CONCLUSION: This study indicates that p53 expression and the apoptotic index are prognostic factors with regard to local control in patients with inoperable NSCLC treated with radiotherapy and by combining these 2 factors, a clinically relevant estimation of the local control probability can be made. The apoptotic index turned out to be the only factor significantly related to survival.

Fixation induced variations in quantitative nuclear image features in sections.

Recently quantitative nuclear image features (Q.N.I. features) have become available which have proven to be accurate descriptors of different chromatin patterns. Therefore it can be expected that these features will become increasingly important in diagnostic histopathology. However, if used for routine applications in human pathology, it is to be questioned to which extent Q.N.I. features are able to discriminate between subpopulations of nuclei and to which extent fixation induced variations on Q.N.I. features do exist. In the present study, the discriminating capacity of the Q.N.I. features on the basal and parabasal cell nuclei of human cervical epithelium is investigated. Fixation is varied in concentration, temperature, and time. The results emphasize the excellent discriminating power of the Q.N.I. features and indicate that if a) the concentration is kept between 4 and 6% w/v, b) the temperature of the fixative is room temperature, and c) the fixation time is kept constant at 24 or 36 h, the Q.N.I. features can well be used in histopathology.

Metabolic activity measured by FDG PET predicts pathological response in locally advanced superior sulcus NSCLC.

OBJECTIVES: Pathological complete response and tumor regression to less than 10% vital tumor cells after induction chemoradiotherapy have been shown to be prognostically important in non-small cell lung cancer (NSCLC). Predictive imaging biomarkers could help treatment decision-making. The purpose of this study was to assess whether postinduction changes in tumor FDG uptake could predict pathological response and to evaluate the correlation between residual vital tumor cells and post-induction FDG uptake. METHODS: NSCLC patients with sulcus superior tumor (SST), planned for trimodality therapy, routinely undergo FDG PET/CT scans before and after induction chemoradiotherapy in our institute. Metabolic end-points based on standardized uptake values (SUV) were calculated, including SUV(max) (maximum SUV), SUV(TTL) (tumor-to-liver ratio), SUV(peak) (SUV within 1 cc sphere with highest activity), and SUV(PTL) (peak-to-liver ratio). Pathology specimens were assessed for residual vital tumor cell percentages and scored as no (grade 3), <10% (grade 2b) and >10% vital tumor cells (grade 2a/1). RESULTS: 19 and 23 patients were evaluated for (1) metabolic change and (2) postinduction PET-pathology correlation, respectively. Changes in all parameters were predictive for grade 2b/3 response. ΔSUV(TTL) and ΔSUV(PTL) were also predictive for grade 3 response. Remaining vital tumor cells correlated with post-induction SUV(peak) (R=0.55; P=0.007) and postinduction SUV(PTL) (R=0.59; P=0.004). Postinduction SUV(PTL) could predict both grades 3 and 2b/3 response. CONCLUSION: In NSCLC patients treated with chemoradiotherapy, changes in SUV(max), SUV(TTL), SUV(peak), and SUV(PTL) were predictive for pathological response (grade 2b/3 and for SUV(TTL) and SUV(PTL) grade 3 as well). Postinduction SUV(PTL) correlated with residual tumor cells.

Incidence of T790M mutation in (sequential) rebiopsies in EGFR-mutated NSCLC-patients.

AIM: Non-small cell lung cancer (NSCLC)-patients with an epidermal growth factor receptor (EGFR)-mutation have median progression-free survival (PFS) of 12 months on tyrosine kinase inhibitors (TKIs). Resistance is mediated by the EGFR T790M-mutation in the majority of patients. Longitudinal follow-up data are lacking. We retrospectively evaluated EGFR-mutated NSCLC-patients who were rebiopsied after TKI-treatment. A subgroup was sequentially rebiopsied along the course of the disease. PATIENTS AND METHODS: Advanced EGFR-mutated NSCLC-patients who had both a pre-TKI biopsy and post-TKI biopsy available were included. Information on treatments and (re)biopsies was collected chronologically. Primary endpoint was the incidence of the T790M-mutation. RESULTS: Sixty-six patients fulfilled the inclusion criteria. In first post-TKI biopsies, T790M-mutation was detected in 34 patients (52%) of patients. Twenty-seven patients had subsequent post-TKI rebiopsies with mutation analysis available; in 10 patients (37%) the T790M-status in subsequent post-TKI rebiopsies was not consistent with the T790M-status of the first post-TKI biopsy. Progression free survival (PFS) on TKI-treatment was 12.0 months. Objective response rate on TKI-treatment was 81%. Patients developing T790M-mutation at post-TKI biopsy had longer median PFS compared to T790M-negative patients (14.2 versus 11.1 months respectively (P=0.034)) and longer overall survival (45.9 months versus 29.8 months respectively (P=0.213)). Transformation to SCLC was detected in 1 patient (2%). CONCLUSION: Incidence of T790M-mutation at first post-TKI biopsy in this cohort of EGFR-mutated NSCLC-patients was 52%. Detection of T790M-mutation was not consistent over time; some patients who were T790M-positive at first post-TKI biopsy became T790M-negative in later post-TKI rebiopsies and vice versa. T790M-positive patients showed longer PFS than T790M-negative patients. Whether the low incidence of transformation to SCLC is justifying post-TKI rebiopsy in EGFR-mutated NSCLC-patients with acquired TKI-resistance in regular clinical practice is debatable.