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.

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.

Nintedanib for the treatment of symptomatic radiation pneumonitis. A Case Report.

Radiation induced pneumonitis is a common side effect of thoracic radiotherapy. We report a case of a patient diagnosed with symptomatic radiation pneumonitis and a serious contra-indication for corticosteroids. For that reason, the patient was treated with nintedanib instead. After several weeks of treatment her symptoms and chest CT improved significantly. This case shows that nintedanib might be an effective treatment of radiation pneumonitis if corticosteroids are contra-indicated.

Renal cancer and pneumothorax risk in Birt-Hogg-Dubé syndrome; an analysis of 115 FLCN mutation carriers from 35 BHD families.

BACKGROUND: Birt-Hogg-Dubé (BHD) syndrome is an autosomal dominant condition caused by germline FLCN mutations, and characterised by fibrofolliculomas, pneumothorax and renal cancer. The renal cancer risk, cancer phenotype and pneumothorax risk of BHD have not yet been fully clarified. The main focus of this study was to assess the risk of renal cancer, the histological subtypes of renal tumours and the pneumothorax risk in BHD. METHODS: In this study we present the clinical data of 115 FLCN mutation carriers from 35 BHD families. RESULTS: Among 14 FLCN mutation carriers who developed renal cancer 7 were <50 years at onset and/or had multifocal/bilateral tumours. Five symptomatic patients developed metastatic disease. Two early-stage cases were diagnosed by surveillance. The majority of tumours showed characteristics of both eosinophilic variants of clear cell and chromophobe carcinoma. The estimated penetrance for renal cancer and pneumothorax was 16% (95% minimal confidence interval: 6-26%) and 29% (95% minimal confidence interval: 9-49%) at 70 years of age, respectively. The most frequent diagnosis in families without identified FLCN mutations was familial multiple discoid fibromas. CONCLUSION: We confirmed a high yield of FLCN mutations in clinically defined BHD families, we found a substantially increased lifetime risk of renal cancer of 16% for FLCN mutation carriers. The tumours were metastatic in 5 out of 14 patients and tumour histology was not specific for BHD. We found a pneumothorax risk of 29%. We discuss the implications of our findings for diagnosis and management of BHD.

1st ESMO Consensus Conference in lung cancer; Lugano 2010: small-cell lung cancer.

The 1st ESMO Consensus Conference on lung cancer was held in Lugano, Switzerland on 21st and 22nd May 2010 with the participation of a multidisciplinary panel of leading professionals in pathology and molecular diagnostics and medical, surgical and radiation oncology. Before the conference, the expert panel prepared clinically relevant questions concerning five areas as follows: early and locally advanced non-small-cell lung cancer (NSCLC), first-line metastatic NSCLC, second-/third-line NSCLC, NSCLC pathology and molecular testing, and small-cell lung cancer (SCLC) to be addressed through discussion at the Consensus Conference. All relevant scientific literature for each question was reviewed in advance. During the Consensus Conference, the panel developed recommendations for each specific question. The consensus agreement in SCLC is reported in this article. The recommendations detailed here are based on an expert consensus after careful review of published data. All participants have approved this final update.

Outcomes of concurrent chemoradiotherapy in patients with stage III non-small-cell lung cancer and significant comorbidity.

BACKGROUND: published trials of concurrent chemoradiotherapy (CCRT) in stage III non-small-cell lung cancer (NSCLC) generally excluded patients with significant comorbidity. We evaluated outcomes in patients who were selected by using radiation planning parameters and were considered, despite comorbidity, fit enough to receive cisplatin-based chemotherapy. PATIENTS AND METHODS: from 2003 to 2008, 89 patients with stage III NSCLC fit to receive cisplatin-based chemotherapy and a V(20) <42% underwent CCRT at one center outside clinical trials. Most received one cycle of cisplatin-gemcitabine, followed by two to three cycles of cisplatin-etoposide concurrent with involved-field thoracic radiotherapy between 46 and 66 Gy. RESULTS: median age was 64 years; performance status (PS) of zero, one or two in 20/64/5 patients; one or more comorbidities in 41.6%; 14% were treated previously for NSCLC. Median V(20) was 26.6% (range 4%-39.4%). Grade III esophagitis and pneumonitis occurred in 28.1% and 7.9% of patients, respectively, while 4.5% died during treatment. Median overall survival was 18.2 months [95% confidence interval (CI) 13.1-23.3 months]. Independent prognostic factors for overall survival were PS (0 versus ≥ 1, P = 0.041) and planning target volume (P = 0.022). CONCLUSIONS: patients with significant comorbidity who are fit to undergo cisplatin-based CCRT achieve median survivals similar to that reported in phase III trials and with relatively few late toxic effects.

Iron deficiency is common in idiopathic pulmonary arterial hypertension.

The aims of this study were to assess the prevalence of iron deficiency in idiopathic pulmonary arterial hypertension (IPAH) and investigate whether oral iron supplementation has effects in iron-deficient patients. Iron parameters were measure for all IPAH patients attending our centre (VU University Medical Center, Amsterdam, the Netherlands) between May 2009 and February 2010. Iron data were related to clinical parameters, including 6-min walking distance (6MWD), and haemodynamic parameters measured during right heart catheterisation. In a subset of iron-deficient patients, the uptake of iron from the bowel was studied after administering oral iron for 4 weeks. Iron deficiency was found in 30 (43%) out of 70 patients. 6MWD was reduced in iron-deficient patients compared with iron-sufficient patients (mean±sd 390±138 versus 460±143 m; p<0.05) irrespective of the existence of anaemia. In a subset of 18 patients that received oral iron, ferritin levels were significantly increased, although eight patients only slightly increased their iron storage. This study shows that iron deficiency is frequently present in IPAH and is associated with a lower exercise capacity. The small response to oral iron in 44% of the treated patients suggests impaired iron absorption in these patients.

Short-term outpatient follow-up of COVID-19 patients: A multidisciplinary approach.

BACKGROUND: Short-term follow-up of COVID-19 patients reveals pulmonary dysfunction, myocardial damage and severe psychological distress. Little is known of the burden of these sequelae, and there are no clear recommendations for follow-up of COVID-19 patients.In this multi-disciplinary evaluation, cardiopulmonary function and psychological impairment after hospitalization for COVID-19 are mapped. METHODS: We evaluated patients at our outpatient clinic 6 weeks after discharge. Cardiopulmonary function was measured by echocardiography, 24-hours ECG monitoring and pulmonary function testing. Psychological adjustment was measured using questionnaires and semi-structured clinical interviews. A comparison was made between patients admitted to the general ward and Intensive care unit (ICU), and between patients with a high versus low functional status. FINDINGS: Eighty-one patients were included of whom 34 (41%) had been admitted to the ICU. New York Heart Association class II-III was present in 62% of the patients. Left ventricular function was normal in 78% of patients. ICU patients had a lower diffusion capacity (mean difference 12,5% P = 0.01), lower forced expiratory volume in one second and forced vital capacity (mean difference 14.9%; P<0.001; 15.4%; P<0.001; respectively). Risk of depression, anxiety and PTSD were 17%, 5% and 10% respectively and similar for both ICU and non-ICU patients. INTERPRETATION: Overall, most patients suffered from functional limitations. Dyspnea on exertion was most frequently reported, possibly related to decreased DLCOc. This could be caused by pulmonary fibrosis, which should be investigated in long-term follow-up. In addition, mechanical ventilation, deconditioning, or pulmonary embolism may play an important role.

Opposite effects of training in rats with stable and progressive pulmonary hypertension.

BACKGROUND: Exercise training in pulmonary arterial hypertension (PH) is a promising adjunct to medical treatment. However, it is still unclear whether training is beneficial for all PH patients. We hypothesized that right ventricular adaptation plays a pivotal role in the response to training. METHODS AND RESULTS: Two different dosages of monocrotaline were used in rats to model stable PH with preserved cardiac output and progressive PH developing right heart failure. Two weeks after injection, PH was confirmed by echocardiography, and treadmill training was initiated. Rats were trained for 4 weeks unless manifest right heart failure developed earlier. At the end of the study protocol, all rats were functionally assessed by endurance testing, echocardiography, and invasive pressure measurements. Lungs and hearts were further analyzed in quantitative histomorphologic analyses. In stable PH, exercise training was well tolerated and markedly increased exercise endurance (from 25+/-3.9 to 62+/-3.9 minutes; P<0.001). Moreover, capillary density increased significantly (from 1.21+/-0.12 to 1.51+/-0.07 capillaries per cardiomyocyte; P<0.05). However, in progressive PH, exercise training worsened survival (hazard ratio, 2.7; 95% confidence interval, 1.1 to 14.2) and increased pulmonary vascular remodeling. In addition, training induced widespread leukocyte infiltration into the right ventricle (from 135+/-14 to 276+/-18 leukocytes per 1 mm(2); P<0.001). CONCLUSIONS: In our rat model, exercise training was found to be beneficial in stable PH but detrimental in progressive PH. Future studies are necessary to address the clinical implications of our findings.

Genetic and environmental influences on objective intermediate asthma phenotypes in Dutch twins.

It is unclear to what extent the same set of environmental or genetic factors regulate objective intermediate asthma phenotypes. We examined heritabilities of these phenotypes and estimated their environmental and genetic overlap. We studied baseline lung function (forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC) and FEV(1)/FVC), bronchial hyperresponsiveness, number of positive skin prick tests (SPT) to 11 allergens, serum total immunoglobulin (Ig)E, number of positive specific IgE tests to four allergens and eosinophil counts. 103 twin pairs were studied (46 monozygotic and 57 dizygotic; mean age: 22.5 yrs, range: 17.0-27.0 yrs). Univariate and bivariate genetic analyses were performed after adjustment for significant covariates. All intermediate asthma phenotypes showed significant heritabilities (47-83%). Most phenotypes were substantially correlated, which was mainly due to shared genetic factors. Pairs of phenotypes with the largest genetic correlations were specific IgE and SPT (0.98), and total IgE with specific IgE (0.87), with SPT (0.72), and with eosinophils (0.62). SPT showed significant environmental correlations with total IgE (0.65), specific IgE (0.70) and bronchial hyperresponsiveness (0.44). Genetic effects explain the majority of the variation in objective intermediate asthma phenotypes. Additionally, correlations between pairs of these traits are also mainly explained by genetic rather than environmental factors.

Fasudil reduces monocrotaline-induced pulmonary arterial hypertension: comparison with bosentan and sildenafil.

Pulmonary arterial hypertension (PAH) still cannot be cured, warranting the search for novel treatments. Fasudil (a Rho kinase inhibitor) was compared with bosentan (an endothelin receptor blocker) and sildenafil (a phosphodiesterase 5 inhibitor), with emphasis on right ventricular (RV) function, in a reversal rat model of monocrotaline (MCT)-induced PAH. In addition, the effects of combining bosentan or sildenafil with fasudil were studied. MCT (40 mg·kg body weight(-1)) induced clear PAH in male Wistar rats (n = 9). After 28 days, echocardiography, RV catheterisation and histochemistry showed that cardiac frequency, stroke volume and RV contractility had deteriorated, accompanied by RV dilatation and hypertrophy, and marked pulmonary arterial wall thickening. Mean pulmonary arterial pressure and pulmonary vascular resistance increased significantly compared to healthy rats (n = 9). After 14 days, MCT-treated rats received a 14-day oral treatment with bosentan, sildenafil, fasudil or a combination of fasudil with either bosentan or sildenafil (all n = 9). All treatments preserved cardiac frequency, stroke volume and RV contractility, and reduced pulmonary vascular resistance and RV dilatation. Fasudil lowered RV systolic pressure and mean pulmonary arterial pressure significantly, by reducing pulmonary arterial remodelling, which reduced RV hypertrophy. Combining bosentan or sildenafil with fasudil had no synergistic effect. Fasudil significantly improved PAH, to a greater degree than did bosentan and sildenafil.

RC time constant of single lung equals that of both lungs together: a study in chronic thromboembolic pulmonary hypertension.

The product of resistance, R, and compliance, C (RC time), of the entire pulmonary circulation is constant. It is unknown if this constancy holds for individual lungs. We determined R and C in individual lungs in chronic thromboembolic pulmonary hypertension (CTEPH) patients where resistances differ between both lungs. Also, the contribution of the proximal pulmonary arteries (PA) to total lung compliance was assessed. Patients (n=23) were referred for the evaluation of CTEPH. Pressure was measured by right heart catheterization and flows in the main, left, and right PA by magnetic resonance imaging. Total, left, and right lung resistances were calculated as mean pressure divided by mean flow. Total, left, and right lung compliances were assessed by the pulse pressure method. Proximal compliances were derived from cross-sectional area change DeltaA and systolic-diastolic pressure difference DeltaP (DeltaA/DeltaP) in main, left, and right PA, multiplied by vessel length. The lung with the lowest blood flow was defined "low flow" (LF), the contralateral lung "high flow" (HF). Total resistance was 0.57+/-0.28 mmHg.s(-1).ml(-1), and resistances of LF and HF lungs were 1.57+/-0.2 vs. 1.00+/-0.1 mmHg.s(-1).ml(-1), respectively, P<0.0001. Total compliance was 1.22+/-1.1 ml/mmHg, and compliances of LF and HF lung were 0.47+/-0.11 and 0.62+/-0.12 ml/mmHg, respectively, P=0.01. Total RC time was 0.49+/-0.2 s, and RC times for the LF and HF lung were 0.45+/-0.2 and 0.45+/-0.1 s, respectively, not different. Proximal arterial compliance, given by the sum of main, right, and left PA compliances, was only 19% of total lung compliance. The RC time of a single lung equals that of both lungs together, and pulmonary arterial compliance comes largely from the distal vasculature.

Tuberculosis complicating imatinib treatment for chronic myeloid leukaemia.

Although imatinib is not considered a predisposing factor for tuberculosis (TB), the present case report describes three patients in whom imatinib treatment for chronic myeloid leukaemia was complicated by TB. This raises the question of whether imatinib increases susceptibility to TB. There are several reports suggesting that imatinib might impair the immune system, leading to a variety of infections, including varicella zoster and hepatitis B. Control of TB in healthy individuals is achieved through acquired immunity, in which antigen-specific T-cells and macrophages arrest growth of Mycobacterium tuberculosis bacilli and maintain control over persistent bacilli. In the chronic stage of the infection, CD8+ T-cells assist macrophages in controlling intracellular mycobacteria. The T-cell receptor orchestrates this process. The fact that tyrosine kinases play an important role in T-cell receptor signal transduction and that imatinib has been shown to affect T-cell receptor signal transduction, presents a mechanism by which imatinib might impair control of Mycobacterium tuberculosis; thereby leaving the host susceptible to reactivation of tuberculosis.

Pulmonary arterial hypertension in limited cutaneous systemic sclerosis: a distinctive vasculopathy.

Systemic sclerosis-associated pulmonary arterial hypertension (SScPAH) has a worse prognosis and response to pulmonary arterial hypertension (PAH) therapy than idiopathic PAH (IPAH). These differences have not yet been explained. Knowledge concerning histological pulmonary vasculopathy in SScPAH is limited in contrast to IPAH. Therefore, we explored patterns of vasculopathy in SScPAH compared with IPAH. Parameters of vasculopathy were assessed from lung tissue of eight PAH patients with limited cutaneous systemic sclerosis and 11 IPAH patients. Lung tissue was obtained at autopsy (n = 15), explantation (n = 3) and biopsy (n = 1). Pulmonary arterial/arteriolar intimal fibrosis was identified in all SScPAH patients and in three IPAH patients (p = 0.003). Fibrosis of pulmonary veins/venules was found in all SScPAH patients and in three IPAH patients (p = 0.003). In four SScPAH patients, fibrosis of veins/venules was focal and associated with capillary congestion as in pulmonary veno-occlusive disease (PVOD). Of the IPAH patients, 10 had unequivocal evidence of plexogenic arteriopathy compared with none of the SScPAH patients (p = 0.001). SScPAH is characterised by small vessel intimal fibrosis, which is associated with a PVOD-like pattern in some cases. This might explain its different clinical behaviour from IPAH. Small vessel intimal fibrosis may provide clues to elucidation of differences in pathogenetic mechanisms between the groups.

Effects of exercise training in patients with idiopathic pulmonary arterial hypertension.

We determined the physiological effects of exercise training on exercise capacity and quadriceps muscle function in patients with idiopathic pulmonary arterial hypertension (iPAH). In total, 19 clinically stable iPAH patients (New York Heart Association II-III) underwent a supervised exercise training programme for the duration of 12 weeks. Maximal capacity, endurance capacity and quadriceps function were assessed at baseline and after 12 weeks. In 12 patients, serial quadriceps muscle biopsies were obtained. 6-min walk distance and peak exercise capacity did not change after training. However, endurance capacity improved significantly after training, demonstrated by a shift of the anaerobic threshold to a higher workload (from 32+/-5 to 46+/-6 W; p = 0.003) together with an increase in exercise endurance time (p<0.001). Moreover, exercise training increased quadriceps strength by 13% (p = 0.005) and quadriceps endurance by 34% (p = 0.001). Training enhanced aerobic capacity of the quadriceps, by increasing capillarisation (1.36+/-0.10 to 1.78+/-0.13 capillaries per muscle fibre; p<0.001) and oxidative enzyme activity, especially of the type-I (slow) muscle fibres. No changes were found in cross-sectional area and fibre type distribution. Exercise training in iPAH improves exercise endurance and quadriceps muscle function, which is also reflected by structural changes of the quadriceps.

Nailfold capillary density is associated with the presence and severity of pulmonary arterial hypertension in systemic sclerosis.

OBJECTIVE: The aim of this study was to investigate whether there are differences in capillary nailfold changes in patients with systemic sclerosis (SSc) with and without pulmonary arterial hypertension (PAH), and whether these changes are associated with PAH severity and disease specificity. METHODS: Capillary density and loop dimensions were studied in 21 healthy controls, 20 patients with idiopathic PAH (IPAH) and 40 patients with SSc. Of the 40 patients with SSc, 19 had no PAH (SSc-nonPAH) and 21 had PAH (SSc-PAH), of whom eight had PAH during exercise. RESULTS: Capillary density was lower in SSc-PAH compared with patients who had SSc-nonPAH (4.33/mm vs 6.56/mm respectively, p = 0.001), but loop dimensions were equal. In comparison with IPAH, patients with SSc-PAH had reduced capillary density (4.33/mm vs 7.86/mm, p<0.001) and larger loop dimensions (total width 101.05 microm vs 44.43 microm, p<0.001). Capillary density in healthy controls (9.87/mm) was significantly higher when compared with SSc-nonPAH (6.56/mm), SSc-PAH (4.33/mm) and with IPAH (7.86/mm). No differences in capillary dimensions were present between healthy controls and IPAH. Capillary density correlated with mean pulmonary arterial pressure (PAP) at rest in SSc-PAH at rest (r = -0.58, p = 0.039) and IPAH (r = -0.67, p = 0.001). CONCLUSIONS: Reduction of nailfold capillary density, but not capillary loop dimensions is associated with PAH, and correlates with the severity of PAH in both SSc and IPAH. This suggests that either systemic microvascular changes play a part in the development of PAH, or that PAH itself contributes to systemic microvascular changes.

Association and interaction analyses of eight genes under asthma linkage peaks.

BACKGROUND: Linkage studies have implicated the 2q33, 9p21, 11q13 and 20q13 regions in the regulation of allergic disease. The aim of this study was to test genetic variants in candidate genes from these regions for association with specific asthma traits. METHODS: Ninety-five single nucleotide polymorphisms (SNP) located in eight genes (CD28, CTLA4, ICOS, ADAM23, ADAMTSL1, MS4A2, CDH26 and HRH3) were genotyped in >5000 individuals from Australian (n = 1162), Dutch (n = 99) and Danish (n = 303) families. Traits tested included doctor-diagnosed asthma, atopy, airway obstruction, total serum immunoglobulin (Ig) E levels and eosinophilia. Association was tested using both multivariate and univariate methods, with gene-wide thresholds for significance determined through simulation. Gene-by-gene and gene-by-environment analyses were also performed. RESULTS: There was no overall evidence for association with seven of the eight genes tested when considering all genetic variation assayed in each gene. The exception was MS4A2 on chromosome 11q13, which showed weak evidence for association with IgE (gene-wide P < 0.05, rs502581). There were no significant gene-by-gene or gene-by-environment interaction effects after accounting for the number of tests performed. CONCLUSIONS: The individual variants genotyped in the 2q33, 9p21 and 20q13 regions do not explain a large fraction of the variation in the quantitative traits tested or have a major impact on asthma or atopy risk. Our results are consistent with a weak effect of MS4A2 polymorphisms on the variation of total IgE levels.

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.