The Role of c-Met as a Biomarker and Player in Innate and Acquired Resistance in Non-Small-Cell Lung Cancer: Two New Mutations Warrant Further Studies.

The c-Met receptor is a therapeutically actionable target in non-small-cell lung cancer (NSCLC), with one approved drug and several agents in development. Most suitable biomarkers for patient selection include c-Met amplification and exon-14 skipping. Our retrospective study focused on the frequency of different c-Met aberrations (overexpression, amplification and mutations) in 153 primary, therapy-naïve resection samples and their paired metastases, from Biobank@UZA. Furthermore, we determined the correlation of c-Met expression with clinicopathological factors, Epidermal Growth Factor Receptor (EGFR)-status and TP53 mutations. Our results showed that c-Met expression levels in primary tumors were comparable to their respective metastases. Five different mutations were detected by deep sequencing: three (E168D, S203T, N375S) previously described and two never reported (I333T, G783E). I333T, a new mutation in the Sema(phorin) domain of c-Met, might influence the binding of antibodies targeting the HGF-binding domain, potentially causing innate resistance. E168D and S203T mutations showed a trend towards a correlation with high c-Met expression (p = 0.058). We found a significant correlation between c-MET expression, EGFR expression (p = 0.010) and EGFR mutations (p = 0.013), as well as a trend (p = 0.057) with regards to TP53 mutant activity. In conclusion this study demonstrated a strong correlation between EGFR mutations, TP53 and c-Met expression in therapy-naïve primary resection samples. Moreover, we found two new c-Met mutations that warrant further studies.

Second-line erlotinib after failure of pemetrexed-containing chemotherapy in advanced non-small cell lung cancer (NSCLC): Real-world effectiveness, safety and tolerability.

INTRODUCTION: Little data is available on patients with advanced non-squamous NSCLC treated with erlotinib specifically after failure of first-line pemetrexed-containing chemotherapy. We assessed the effectiveness, safety and tolerability of erlotinib in a real-world setting. METHODS: Prospective single-arm, open-label, multicenter, non-interventional study of erlotinib (150mg daily) in inoperable stage III/IV NSCLC after progression on first-line pemetrexed-containing chemotherapy without EGFR-mutation selection. Patients were followed according to routine practice and response assessment was performed using RECIST 1.1. The primary end point was progression-free survival (PFS). Secondary end points included best confirmed overall response rate (ORR), disease control rate (DCR), and overall survival (OS). Adverse events were recorded. An independent dataset was used to validate the results. RESULTS: In all, 59 patients were screened, 57 enrolled, and 54 (36 men; median age 65 years) included in the per-protocol analysis. Median PFS was 1.8 (95% CI 1.4-2.6) months, with 11% (95% CI 5-21%) alive and progression-free at 6 months. The ORR was 0.0% (97.5% CI 0.0-6.8%) and the DCR 34.6% (95% CI 21.9-49.0%). Median overall survival was 5.8 (95% CI 3.3-8.6) months with 28% (95% CI 17-42%) alive at one year. Rash occurred in 60.7% (95% CI 46.7-73.5%), with severe rash in 12.5% (95% CI 5.1-24.1%). Any grade diarrhea was observed in 42.8% (95% CI 29.7-56.8%), with grade 3 occurring in 7.1% (95% CI 1.9-17.2%). Erlotinib was stopped in 21.0% (95% CI 11.3-33.9%) of patients due to adverse events, which were treatment related in 7%. CONCLUSION: Second-line erlotinib after pemetrexed treatment results in similar real-world outcomes as reported after non-pemetrexed containing first-line therapy. However, the overall duration of response in unselected patients remains limited and other effective treatments have in the meantime been introduced. No new safety signals were detected.

A Multicenter Study to Assess EGFR Mutational Status in Plasma: Focus on an Optimized Workflow for Liquid Biopsy in a Clinical Setting.

A multicenter study was performed to determine an optimal workflow for liquid biopsy in a clinical setting. In total, 549 plasma samples from 234 non-small cell lung cancer (NSCLC) patients were collected. Epidermal Growth Factor Receptor (EGFR) circulating cell-free tumor DNA (ctDNA) mutational analysis was performed using digital droplet PCR (ddPCR). The influence of (pre-) analytical variables on ctDNA analysis was investigated. Sensitivity of ctDNA analysis was influenced by an interplay between increased plasma volume (p < 0.001) and short transit time (p = 0.018). Multistep, high-speed centrifugation both increased plasma generation (p < 0.001) and reduced genomic DNA (gDNA) contamination. Longer transit time increased the risk of hemolysis (p < 0.001) and low temperatures were shown to have a negative effect. Metastatic sites were found to be strongly associated with ctDNA detection (p < 0.001), as well as allele frequency (p = 0.034). Activating mutations were detected in a higher concentration and allele frequency compared to the T790M mutation (p = 0.003, and p = 0.002, respectively). Optimization of (pre-) analytical variables is key to successful ctDNA analysis. Sufficient plasma volumes without hemolysis or gDNA contamination can be achieved by using multistep, high-speed centrifugation, coupled with short transit time and temperature regulation. Metastatic site location influenced ctDNA detection. Finally, ctDNA levels might have further value in detecting resistance mechanisms.

Does nivolumab for progressed metastatic lung cancer fulfill its promises? An efficacy and safety analysis in 20 general hospitals.

OBJECTIVES: In patients with refractory or recurrent non-small-cell lung cancer (NSCLC) after first line chemotherapy, phase III trials showed superiority of nivolumab, an IgG4 programmed death-1 immune-checkpoint-inhibitor antibody, over docetaxel. We evaluated case mix, effectiveness and safety of nivolumab upon implementation in general practice. MATERIALS AND METHODS: In 20 general hospitals, all consecutive NSCLC patients treated with nivolumab within the medical need program (inclusion period 12 months) in Flanders - Belgium were evaluated. RESULTS: There were 267 patients, Eastern Cooperative Oncology Group (ECOG) score was 2 in 24% and 0-1 in 76%. In 48%, two or more systemic regimens were given before nivolumab. The median overall survival was 7.8 months (95% confidence interval (CI) 6.3-9.3). At one year, the overall survival rate was 36.5±0.34%. Median progression-free survival was 3.7 months (95% CI 2.9-4.5). An objective response was obtained in 23.2%. ECOG score 2 and presence of liver metastasis strongly correlated with worse survival (p<0.00001). Treatment related adverse events grade 3 or 4 were reported in 21%, colitis (4%) and pneumonitis (7%) were most frequent. CONCLUSION: Upon implementation of nivolumab therapy in general hospitals, the case mix was characterized by a more heavily pretreated population with a substantial fraction of patients with ECOG score 2. The median overall survival is slightly inferior to what was published in the randomized phase III trials. An ECOG score 2 and the presence of liver metastasis correlated strongly with a worse survival. We report a high prevalence of serious adverse events.

Double Trouble: A Case Series on Concomitant Genetic Aberrations in NSCLC.

Several oncogenic drivers have been identified in non-small cell lung cancer. Targeted therapies for these aberrations have already been successfully developed and implemented in clinical practice. Owing to improved sensitivity in genetic testing, more and more tumors with multiple driver mutations are identified, resulting in dilemmas for treating physicians whether and which targeted therapy to use. In this case series, we provide an overview of patients with intrinsic double mutations in oncogenic drivers and their reported response to targeted therapies, with a focus on epidermal growth factor receptor, anaplastic lymphoma kinase, cMET, and Kirsten rat sarcoma viral oncogene. We also include an unpublished case report on a patient with an epidermal growth factor receptor L858R and cMET exon 14 skipping.

Inhaled treatment of COPD: a Delphi consensus statement.

BACKGROUND: Global Initiative for Chronic Obstructive Lung Disease (GOLD) global strategy (2015) provides guidance for the treatment of chronic obstructive pulmonary disease (COPD) with different first-choice options per GOLD category without specification. OBJECTIVES: To evaluate the level of medical experts' consensus on their preferred first-choice treatment within different COPD categories. METHODS: A two-round Delphi Panel consisting of 15 questions was completed by Belgian pulmonologists (n=31) and European (n=10) COPD experts. RESULTS: Good consensus was reached by both expert groups for long-acting bronchodilators instead of short-acting bronchodilators as first-choice treatment in GOLD A. Single bronchodilation with long-acting muscarinic antagonist (LAMA) was preferred over long-acting ß2-agonist (LABA) and LABA/LAMA as first-choice treatment in GOLD B and GOLD C. For GOLD D patients based on the forced expiratory volume in 1 second (FEV1)<50%, a very good consensus was reached for LAMA/LABA as first-choice treatment. For GOLD D patients based on frequent or severe exacerbations, there was a good consensus for LABA/LAMA/inhaled corticosteroids (ICS) as first choice in the Belgian group. According to the European experts, both LABA/LAMA and LABA/LAMA/ICS could be the first choice for these patients. CONCLUSION: Belgian and European experts recommend long-acting bronchodilators as first-choice treatment. Treatment containing ICS was found only appropriate in patients with FEV1<50% and ≥2 moderate exacerbations or 1 severe exacerbation/year.

Better to be alone than in bad company: The antagonistic effect of cisplatin and crizotinib combination therapy in non-small cell lung cancer.

AIM: To investigate the potential benefit of combining the cMET inhibitor crizotinib and cisplatin we performed in vitro combination studies. METHODS: We tested three different treatment schemes in four non-small cell lung cancer (NSCLC) cell lines with a different cMET/epidermal growth factor receptor genetic background by means of the sulforhodamine B assay and performed analysis with Calcusyn. RESULTS: All treatment schemes showed an antagonistic effect in all cell lines, independent of the cMET status. Despite their different genetic backgrounds, all cell lines (EBC-1, HCC827, H1975 and LUDLU-1) showed antagonistic combination indexes ranging from 1.3-2.7. These results were independent of the treatment schedule. CONCLUSION: These results discourage further efforts to combine cMET inhibition with cisplatin chemotherapy in NSCLC.

Management of crizotinib therapy for ALK-rearranged non-small cell lung carcinoma: an expert consensus.

Within 4 years of the discovery of anaplastic lymphoma kinase (ALK) rearrangements in non-small cell lung cancer (NSCLC), the ALK inhibitor crizotinib gained US and European approval for the treatment of advanced ALK-positive NSCLC. This was due to the striking response data observed with crizotinib in phase I and II trials in patients with ALK-positive NSCLC, as well as the favorable tolerability and safety profile observed. Recently published phase III data established crizotinib as a new standard of care for this NSCLC molecular subset. A consequence of such rapid approval, however, is the limited clinical experience and relative paucity of information concerning optimal therapy management. In this review, we discuss the development of crizotinib and the clinical relevance of its safety profile, examining crizotinib-associated adverse events in detail and making specific management recommendations. Crizotinib-associated adverse events were mostly mild to moderate in severity in clinical studies, and appropriate monitoring and supportive therapies are considered effective in avoiding the need for dose interruption or reduction in most cases. Therapy management of patients following disease progression on crizotinib is also discussed. Based on available clinical data, it is evident that patients may have prolonged benefit from crizotinib after Response Evaluation Criteria in Solid Tumors-defined disease progression, and crizotinib should be continued for as long as the patient derives benefit.

Novel therapeutic strategies for patients with NSCLC that do not respond to treatment with EGFR inhibitors.

INTRODUCTION: Treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) yields tumour responses in non-small cell lung cancer (NSCLC) patients harbouring activating EGFR mutations. However, even in long-lasting responses, resistance to EGFR TKIs invariably occurs. AREAS COVERED: This review examines resistance mechanisms to EGFR TKI treatment, which mainly arise from secondary EGFR mutations. Other resistance-inducing processes include mesenchymal-epithelial transition factor (MET) amplification, epithelial-mesenchymal transformation, phenotypic change from NSCLC to small-cell lung carcinoma, and modifications in parallel signalling pathways. Current therapeutic strategies to overcome these EGFR TKI resistance mechanisms focus on the inhibition or blocking of multiple members of the ErbB family. Several molecules which target multiple ErbB receptors are being investigated in NSCLC and other indications including afatinib, an ErbB Family Blocker, as well as dacomitinib and lapatinib. Novel, non-quinazoline, EGFR inhibitors, that also target EGFR activating and resistance (T790M) mutations, are currently under clinical development. Other therapeutic strategies include inhibition of parallel and downstream pathways, using agents which target heat shock protein (HSP)90 or poly (ADP-ribose) polymerase in addition to mammalian target of rapamycin (mTOR), monoclonal antibodies against the insulin-like growth factor-1 receptor, and fulvestrant-mediated oestrogen receptor regulation. CONCLUSION: Improved understanding of mechanisms underlying resistance to EGFR TKIs emphasises the importance of a genotype-guided approach to therapy. Elucidation of resistance mechanisms is indeed crucial to target innovative therapeutic approaches and to improve the efficacy of anticancer regimes in NSCLC.

ALK and crizotinib: after the honeymoon what else? Resistance mechanisms and new therapies to overcome it.

The last few decades have witnessed a silent revolution in the war against NSCLC, thanks to the discovery of "oncogenic drivers" and the subsequent development of targeted therapies. The discovery of the EML4-ALK fusion gene in a subgroup of patients with NSCLC and the subsequent clinical development of crizotinib has been an amazing success story in lung cancer translational-research, and its accelerated approval [only 4 years from the discovery of ALK rearrangement in NSCLC to the approval by the Food and Drug Administration (FDA)] marked the beginning of the new decade of targeted therapy. However, common to all targeted therapies, despite an initial benefit, patients inevitably experience tumor progression, due to the development of resistance. Several molecular mechanisms are responsible for acquired resistance, such as secondary mutations of ALK kinase domain or amplification of ALK fusion gene, or the activation of other oncogenic drivers, which may cause resistance independently of ALK genetic alterations. Pre-clinical data and early clinical trials showed the promising efficacy of a new class of ALK-inhibitors in overcoming acquired resistance. The inhibition of the molecular chaperone, HSP90, represents another promising strategy to overcome crizotinib resistance in ALK-rearranged NSCLC. Several molecules are currently under investigation in order to establish their specific role in the treatment of ALK-rearranged NSCLC.

Antineoplastic therapy-induced pulmonary toxicity.

Pulmonary complications of antineoplastic therapy are common and are an important cause of respiratory morbidity. The pulmonary toxicity should be taken into account in every patient with respiratory problems who is or has been treated with antineoplastic agents. The diagnosis of drug-induced pulmonary toxicity is complex and should be based on the medical history, clinical, radiological and pathological findings. None of them are specific but they can guide the diagnostic process. The treatment of pulmonary abnormalities caused by chemotherapy is mostly supportive and based on cessation of the causative agent. However, the therapeutic options in oncology setting are usually limited thus the decision about changing the treatment should be taken with caution.

Expressed wishes and incidence of euthanasia in advanced lung cancer patients.

This study explores expressed wishes and requests for euthanasia (i.e. administration of lethal drugs at the explicit request of the patient), and incidence of end-of-life decisions with possible life-shortening effects (ELDs) in advanced lung cancer patients in Flanders, Belgium. We performed a prospective, longitudinal, observational study of a consecutive sample of advanced lung cancer patients and selected those who died within 18 months of diagnosis. Immediately after death, the pulmonologist/oncologist and general practitioner (GP) of the patient filled in a questionnaire. Information was available for 105 out of 115 deaths. According to the specialist or GP, one in five patients had expressed a wish for euthanasia; and three in four of these had made an explicit and repeated request. One in two of these received euthanasia. Of the patients who had expressed a wish for euthanasia but had not made an explicit and repeated request, none received euthanasia. Patients with a palliative treatment goal at inclusion were more likely to receive euthanasia. Death was preceded by an ELD in 62.9% of patients. To conclude, advanced lung cancer patients who expressed a euthanasia wish were often determined. Euthanasia was performed significantly more among patients whose treatment goal after diagnosis was exclusively palliative.

Preferred and actual involvement of advanced lung cancer patients and their families in end-of-life decision making: a multicenter study in 13 hospitals in Flanders, Belgium.

CONTEXT: Death is often preceded by medical decisions that potentially shorten life (end-of-life decisions [ELDs]), for example, the decision to withhold or withdraw treatment. Respect for patient autonomy requires physicians to involve their patients in this decision making. OBJECTIVES: The objective of this study was to examine the involvement of advanced lung cancer patients and their families in ELD making and compare their actual involvement with their previously stated preferences for involvement. METHODS: Patients with Stage IIIb/IV non-small cell lung cancer were recruited by physicians in 13 hospitals and regularly interviewed between diagnosis and death. When the patient died, the specialist and general practitioner were asked to fill in a questionnaire. RESULTS: Eighty-five patients who died within 18 months of diagnosis were studied. An ELD was made in 52 cases (61%). According to the treating physician, half of the competent patients were not involved in the ELD making, one-quarter shared the decision with the physician, and one-quarter made the decision themselves. In the incompetent patients, family was involved in half of cases. Half of the competent patients were involved less than they had previously preferred, and 7% were more involved. Almost all of the incompetent patients had previously stated that they wanted their family involved in case of incompetence, but half did not achieve this. CONCLUSION: In half of the cases, advanced lung cancer patients-or their families in cases of incompetence-were not involved in ELD making, despite the wishes of most of them. Physicians should openly discuss ELDs and involvement preferences with their advanced lung cancer patients.

The effect of clinical covariates on the diagnostic and prognostic value of soluble mesothelin and megakaryocyte potentiating factor.

BACKGROUND: Soluble mesothelin (SM) and megakaryocyte potentiating factor (MPF) are serum biomarkers of mesothelioma. This study examined the effect of clinical covariates on biomarkers levels and their diagnostic and prognostic value. METHODS: Five hundred ninety-four participants were enrolled in a multicenter study, including 106 patients with mesothelioma and 488 control subjects. Multiple linear regression analyses were used to identify which covariates were independently associated with SM and MPF levels. The effect of these covariates on the diagnostic accuracy was evaluated with receiver operating characteristics curve analysis. In patients with mesothelioma, survival analysis was performed with Cox regression. RESULTS: SM and MPF levels were independently associated with age, glomerular filtration rate (GFR), and BMI in control subjects and with GFR and tumor stage in patients with mesothelioma. The diagnostic accuracy of SM and MPF was significantly affected by the distribution of these covariates in the study population. The patients with mesothelioma were best discriminated from the control subjects with either the youngest age, the highest GFR, or the largest BMI. Furthermore, the control subjects were significantly better differentiated from stage II to IV than from stage I mesothelioma. MPF, not SM, was an independent negative prognostic factor, but only if adjusted for the biomarker-associated covariates. CONCLUSIONS: SM and MPF levels were affected by the same clinical covariates, which also had a significant impact on their diagnostic and prognostic value. To improve the interpretation of biomarker results, age, GFR, and BMI should be routinely recorded. Approaches to account for these covariates require further validation, as does the prognostic value of SM and MPF.

Soluble mesothelin, megakaryocyte potentiating factor, and osteopontin as markers of patient response and outcome in mesothelioma.

INTRODUCTION: Soluble mesothelin (SM), megakaryocyte potentiating factor (MPF), and osteopontin (OPN) are blood biomarkers of mesothelioma. This study evaluates their use as markers of response to therapy and outcome. METHODS: Sixty-two patients with malignant pleural mesothelioma were included in an observational multicenter study. Blood samples and matched computed tomography scans were collected at diagnosis and, when possible, during and after therapy. For each patient, the best overall radiological response was compared with the changes in serum SM, MPF, and plasma OPN levels across corresponding time points. RESULTS: In five patients, blood sampling was done shortly before and after extrapleural pneumonectomy. SM and MPF levels markedly decreased after surgery, whereas OPN levels showed a median increase. Fifty-seven patients were surveilled during (and after) chemotherapy, of whom 27 (47%) had stable disease, 14 (25%) partial response, and 16 (28%) progressive disease. In patients with stable disease, SM and MPF levels did not change significantly across the corresponding time points, whereas OPN levels significantly decreased. In those with partial response, SM and MPF levels significantly decreased, whereas OPN levels showed no significant change. In patients with progressive disease, all three biomarker levels significantly increased. Patient responses correlated with a 15% change in all three biomarkers, although SM and MPF appeared more accurate than OPN. Low baseline OPN levels were independently associated with favorable progression-free survival and overall survival. Neither SM nor MPF showed prognostic value. CONCLUSIONS: SM and MPF levels were more closely associated with disease course than OPN and might prove useful in monitoring patient response in mesothelioma. Baseline OPN levels were an independent negative predictor of survival. These promising results require further validation.

Serial measurements of mesothelioma serum biomarkers in asbestos-exposed individuals: a prospective longitudinal cohort study.

INTRODUCTION: Soluble mesothelin (SM) and megakaryocyte potentiating factor (MPF) are serum biomarkers of mesothelioma. This study aims to examine the longitudinal behavior of SM and MPF in controls to gain insight in the optimal use of these biomarkers in screening. METHODS: Asbestos-exposed individuals, with no malignant disease at inclusion, were surveilled for 2 years with annual measurements of SM and MPF. Fixed thresholds were set at 2.10 nmol/L for SM and 13.10 ng/ml for MPF. Longitudinal biomarker analysis, using a random intercept model, estimated the association with age and glomerular filtration rate (GFR), and the intraclass correlation. The latter represents the proportion of total biomarker variance accounted for by the between-individual variance. RESULTS: A total of 215 participants were included, of whom 179 and 137 provided a second sample and third sample, respectively. Two participants with normal SM and MPF levels presented afterward with mesothelioma and lung cancer, respectively. Participants with elevated biomarker levels were typically older and had a lower GFR. During follow-up, biomarker levels significantly increased. Longitudinal analysis indicated that this was in part due to aging, while changes in GFR had a less pronounced effect on serial biomarker measurements. SM and MPF had a high intraclass correlation of 0.81 and 0.78, respectively, which implies that a single biomarker measurement and fixed threshold are suboptimal in screening. CONCLUSIONS: The longitudinal behavior of SM and MPF in controls indicates that a biomarker-based screening approach can benefit from the incorporation of serial measurements and individual-specific screening rules, adjusted for age and GFR. Large-scale validation remains nevertheless mandatory to elucidate whether such an approach can improve the early detection of mesothelioma.

Postextubation obstructive pseudomembranes: a case series and review of a rare complication after endotracheal intubation.

Endotracheal intubation obviously may be life-saving, but it may also lead to complications, including those related to damage of the airways. Superficial damage of the trachea at the site of the endotracheal cuff may trigger the formation of an obstructive fibrinous tracheal pseudomembrane (OFTP). Shortly after extubation, this clot, consisting of fibrin, leucocytes, and necrotic epithelium, can cause stridor due to adherence to the tracheal wall and obstruction of the airway. In most cases, the lesion is easily removed by rigid or fiberoptic bronchoscopy and virtually never leads to permanent damage. The study consisted of case series and review of the literature. This report describes a series of five adult cases and reviews all 19 other previously described cases. A careful analysis of all reported cases, however, did not highlight a simple predisposing factor or illness. It is important to consider OFTP in the differential diagnosis of stridor and respiratory insufficiency in the postextubation period.

Are patients' preferences for information and participation in medical decision-making being met? Interview study with lung cancer patients.

We examined the degree to which newly diagnosed patients with advanced lung cancer wanted to be informed and involved in medical decision-making, and whether the patients felt their preferences were met. Patients from 13 hospitals in Flanders were interviewed with a standard questionnaire. A total of 128 patients (68%) participated. Of the patients who wanted to be informed about life expectancy, half (53%) reported they were informed, and of those who wanted to be informed about palliative care and end-of-life decisions, 25% and 31% said they were informed, respectively. With regard to participation in medical decision-making (in general, about treatment, transfer or end-of-life), patients who preferred the doctor to make decisions or those who preferred to make the decision themselves often achieved this (in their perception), while patients who wanted an in-between position with some involvement, often did not. To conclude, preferences of patients with lung cancer for information concerning delicate topics and for shared decision-making with the physician were not well met.

Validation of computational fluid dynamics in CT-based airway models with SPECT/CT.

PURPOSE: To compare the results obtained by using numerical flow simulations with the results of combined single photon emission computed tomography (SPECT) and computed tomography (CT) and to demonstrate the importance of correct boundary conditions for the numerical methods to account for the large amount of interpatient variability in airway geometry. MATERIALS AND METHODS: This study was approved by all relevant institutional review boards. All patients gave their signed informed consent. In this study, six patients with mild asthma (three men; three women; overall mean age, 46 years ± 17 [standard deviation]) underwent CT at functional residual capacity and total lung capacity, as well as SPECT/CT. CT data were used for segmentation and computational fluid dynamics (CFD) simulations. A comparison was made between airflow distribution, as derived with (a) SPECT/CT through tracer concentration analysis, (b) CT through lobar expansion measurement, and (c) CFD through flow computer simulation. Also, the heterogeneity of the ventilation was examined. RESULTS: Good agreement was found between SPECT/CT, CT, and CFD in terms of airflow distribution and hot spot detection. The average difference for the internal airflow distribution was less than 3% for CFD and CT versus SPECT/CT. Heterogeneity in ventilation patterns could be detected with SPECT/CT and CFD. CONCLUSION: This results of this study show that patient-specific computer simulations with appropriate boundary conditions yield information that is similar to that obtained with functional imaging tools, such as SPECT/CT. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100322/-/DC1.