Low-dose cyclophosphamide depletes circulating naïve and activated regulatory T cells in malignant pleural mesothelioma patients synergistically treated with dendritic cell-based immunotherapy.

Rationale: Regulatory T cells (Treg) play a pivotal role in the immunosuppressive tumor micro-environment in cancer, including mesothelioma. Recently, the combination of autologous tumor lysate-pulsed dendritic cells (DC) and metronomic cyclophosphamide (mCTX) was reported as a feasible and well-tolerated treatment in malignant pleural mesothelioma patients and further as a method to reduce circulating Tregs. Objectives: The aim of this study was to establish the immunological effects of mCTX alone and in combination with DC-based immunotherapy on circulating Treg and other T cell subsets in mesothelioma patients. Methods: Ten patients received mCTX and DC-based immunotherapy after chemotherapy (n = 5) or chemotherapy and debulking surgery (n = 5). Peripheral blood mononuclear cells before, during and after treatment were analyzed for various Treg and other lymphocyte subsets by flow cytometry. Results: After one week treatment with mCTX, both activated FoxP3hi and naïve CD45RA+ Tregs were effectively decreased in all patients. In addition, a shift from naïve and central memory towards effector memory and effector T cells was observed. Survival analysis showed that overall Treg levels before treatment were not correlated with survival, however, nTreg levels before treatment were positively correlated with survival. After completion of mCTX and DC-based immunotherapy treatment, all cell subsets returned to baseline levels, except for the proportions of proliferating EM CD8 T cells, which increased. Conclusions: mCTX treatment effectively reduced the proportions of circulating Tregs, both aTregs and nTregs, thereby favoring EM T cell subsets in mesothelioma patients. Interestingly, baseline levels of nTregs were positively correlated to overall survival upon complete treatment.

Increased T-helper 17.1 cells in sarcoidosis mediastinal lymph nodes.

The lung-draining mediastinal lymph nodes (MLNs) are currently widely used to diagnose sarcoidosis. We previously reported that T-helper (Th) 17.1 cells are responsible for the exaggerated interferon-γ production in sarcoidosis lungs. In this study, we aimed to investigate 1) whether Th17.1 cells are also increased in the MLNs of sarcoidosis patients and 2) whether frequencies of the Th17.1 cells at diagnosis may correlate with disease progression.MLN cells from treatment-naive pulmonary sarcoidosis patients (n=17) and healthy controls (n=22) and peripheral blood mononuclear cells (n=34) and bronchoalveolar lavage fluid (BALF) (n=36) from sarcoidosis patients were examined for CD4+ T-cell subset proportions using flow cytometry.Higher proportions of Th17.1 cells were detected in sarcoidosis MLNs than in control MLNs. Higher Th17.1 cell proportions were found in sarcoidosis BALF compared with MLNs and peripheral blood. Furthermore, BALF Th17.1 cell proportions were significantly higher in patients developing chronic disease than in patients undergoing resolution within 2 years of clinical follow-up.These data suggest that Th17.1 cell proportions in pulmonary sarcoidosis can be evaluated as a diagnostic and/or prognostic marker in clinical practice and could serve as a new therapeutic target.

The Notch pathway inhibitor stapled α-helical peptide derived from mastermind-like 1 (SAHM1) abrogates the hallmarks of allergic asthma.

BACKGROUND: The Notch signaling pathway has been implicated in the pathogenesis of allergic airway inflammation. Targeting the active Notch transactivation complex by using the cell-permeable, hydrocarbon-stapled synthetic peptide stapled α-helical peptide derived from mastermind-like 1 (SAHM1) resulted in genome-wide suppression of Notch-activated genes in leukemic cells and other models. However, the efficacy of SAHM1 in allergic asthma models has remained unexplored. OBJECTIVE: We aimed to investigate the therapeutic efficacy of SAHM1 in a house dust mite (HDM)-driven asthma model. METHODS: Topical therapeutic intervention with SAHM1 or a control peptide was performed during sensitization, challenge, or both with HDM in mice. Airway inflammation was assessed by using multicolor flow cytometry, and bronchial hyperreactivity was studied. Additionally, SAHM1 therapy was investigated in mice with established allergic airway inflammation and in a model in which we neutralized IFN-γ during HDM challenge to support the TH2 response and exacerbate asthma. RESULTS: SAHM1 treatment during the challenge phase led to a marked reduction of eosinophil and T cell numbers in bronchoalveolar lavage fluid compared with those in diluent-treated or control peptide-treated mice. Likewise, T-cell cytokine content and bronchial hyperreactivity were reduced. SAHM1 treatment dampened TH2 inflammation during ongoing HDM challenge and enhanced recovery after established asthma. Additionally, in the presence of anti-IFN-γ antibodies, SAHM1 downregulated expression of the key TH2 transcription factor GATA3 and intracellular IL-4 in bronchoalveolar lavage fluid T cells, but expression of the TH17 transcription factor retinoic acid-related orphan receptor γt or intracellular IL-17 was not affected. SAHM1 therapy also reduced serum IgE levels. CONCLUSIONS: Therapeutic intervention of Notch signaling by SAHM1 inhibits allergic airway inflammation in mice and is therefore an interesting new topical treatment opportunity in asthmatic patients.

Autologous Dendritic Cells Pulsed with Allogeneic Tumor Cell Lysate in Mesothelioma: From Mouse to Human.

Purpose: Mesothelioma has been regarded as a nonimmunogenic tumor, which is also shown by the low response rates to treatments targeting the PD-1/PD-L1 axis. Previously, we demonstrated that autologous tumor lysate-pulsed dendritic cell (DC) immunotherapy increased T-cell response toward malignant mesothelioma. However, the use of autologous tumor material hampers implementation in large clinical trials, which might be overcome by using allogeneic tumor cell lines as tumor antigen source. The purpose of this study was to investigate whether allogeneic lysate-pulsed DC immunotherapy is effective in mice and safe in humans.Experimental Design: First, in two murine mesothelioma models, mice were treated with autologous DCs pulsed with either autologous or allogeneic tumor lysate or injected with PBS (negative control). Survival and tumor-directed T-cell responses of these mice were monitored. Results were taken forward in a first-in-human clinical trial, in which 9 patients were treated with 10, 25, or 50 million DCs per vaccination. DC vaccination consisted of autologous monocyte-derived DCs pulsed with tumor lysate from five mesothelioma cell lines.Results: In mice, allogeneic lysate-pulsed DC immunotherapy induced tumor-specific T cells and led to an increased survival, to a similar extent as DC immunotherapy with autologous tumor lysate. In the first-in-human clinical trial, no dose-limiting toxicities were established and radiographic responses were observed. Median PFS was 8.8 months [95% confidence interval (CI), 4.1-20.3] and median OS not reached (median follow-up = 22.8 months).Conclusions: DC immunotherapy with allogeneic tumor lysate is effective in mice and safe and feasible in humans. Clin Cancer Res; 24(4); 766-76. ©2017 AACR.

No evidence found for an association between prednisone dose and FVC change in newly-treated pulmonary sarcoidosis.

BACKGROUND: Prednisone is used as first-line therapy for pulmonary sarcoidosis. What dosing strategy has the best balance between effect and side-effects is largely unknown. We analyzed change in forced vital capacity (FVC) and weight during different prednisone doses used in daily practice for treatment naïve pulmonary sarcoidosis patients. METHODS: Multilevel models were used to describe FVC and weight change over time. Correlations were calculated using linear regression models. RESULTS: Fifty-four patients were included. FVC changed over time (p < 0.001), with an average increase of 9.6% predicted (95% CI: 7.2 to 12.1) at 12 months. Weight changed significantly over time (p < 0.001), with an average increase of 4.3 kg (95% CI: 3.0 to 5.6) at 12 months. Although FVC and weight changed significantly over time, there was little correlation between prednisone dose and FVC change, while weight increase correlated significantly with cumulative prednisone dose at 24 months. In patients treated with a high cumulative prednisone dose, baseline FVC was on average lower (p = 0.001) compared to low dose treated patients, while no significant differences were observed in need for second/third-line therapy or number of exacerbations. A strategy leading to a low cumulative dose at 12 months was defined by rapid dose tapering to 10 mg/day within 3.5 months. CONCLUSIONS: These results suggest that prednisone therapy aimed at improving or preserving FVC in newly- treated pulmonary sarcoidosis can often be reduced in dose, using a treatment regimen that is characterized by early dose tapering.

What patients with pulmonary fibrosis and their partners think: a live, educative survey in the Netherlands and Germany.

Pulmonary fibrosis greatly impacts patients and their partners. Unmet needs of patients are increasingly acknowledged; the needs of partners often remain unnoticed. Little is known about the best way to educate patients and partners. We investigated pulmonary fibrosis patients' and partners' perspectives and preferences in care, and the differences in these between the Netherlands and Germany. Additionally, we evaluated whether interactive interviewing could be a novel education method in this population. Patients and partners were interviewed during pulmonary fibrosis patient information meetings. In the Netherlands, voting boxes were used and results were projected directly. In Germany, questionnaires were used. In the Netherlands, 278 patients and partners participated; in Germany, 51. Many participants experienced anxiety. Almost all experienced misunderstanding, because people do not know what pulmonary fibrosis is. All expressed a need for information, psychological support and care for partners. Use of the interactive voting system was found to be pleasant (70%) and informative (94%). This study improves the knowledge of care needs of patients with pulmonary fibrosis and their partners. There were no major differences between the Netherlands and Germany. Interactive interviewing could be an attractive method to acquire insights into the needs and preferences of patients and partners, while providing them with information at the same time.

Efficacy of Tumor Vaccines and Cellular Immunotherapies in Non-Small-Cell Lung Cancer: A Systematic Review and Meta-Analysis.

PURPOSE: Programmed cell death protein-1- checkpoint blockers have recently been approved as second-line treatment for advanced non-small-cell lung cancer (NSCLC). Unfortunately, only a subgroup of patients responds and shows long-term survival to these therapies. Tumor vaccines and cellular immunotherapies could synergize with checkpoint blockade, but which of these treatments is most efficacious is unknown. In this meta-analysis, we assessed the efficacy of tumor vaccination and cellular immunotherapy in NSCLC. METHODS: We searched for randomized controlled trials (RCTs) investigating cellular immunotherapy or vaccines in NSCLC. We used random effects models to analyze overall survival (OS) and progression-free survival (PFS), expressed as hazard ratios (HRs), and differences in time (months). The effect of immunotherapy type, disease stage, tumor histology, and concurrent chemotherapy was assessed using subgroup analysis and meta-regression. All procedures were performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS: We identified 18 RCTs that matched our selection criteria; these included a total of 6,756 patients. Immunotherapy extended NSCLC survival and PFS, expressed as HR (OS: HR, 0.81, 95% CI, 0.70 to 0.94, P = .01; PFS: HR, 0.83, 95% CI, 0.72 to 0.95, P = .006) and month difference (OS: difference, 5.43 months, 95% CI, 3.20 to 7.65, P < .005; PFS: difference, 3.24 months, 95% CI, 1.61 to 4.88, P < .005). Cellular therapies outperformed tumor vaccines (OS as HR: P = .005, month difference: P < .001; PFS as HR: P = .001, month difference: P = .004). There was a benefit of immunotherapy in low-stage compared with high-stage NSCLC and with concurrent administration of chemotherapy only in one of four outcome measures evaluated (PFS in months: P = .01 and PFS as HR: P = .031, respectively). There was no significant effect of tumor histology on survival or PFS. CONCLUSION: Tumor vaccines and cellular immunotherapies enhanced OS and PFS in NSCLC. Cellular immunotherapy was found to be more effective than tumor vaccination. These findings have implications for future studies investigating combination immunotherapy in NSCLC.

T cells are necessary for ILC2 activation in house dust mite-induced allergic airway inflammation in mice.

Allergic asthma is a chronic inflammation of the airways mediated by an adaptive type 2 immune response. Upon allergen exposure, group 2 innate lymphoid cells (ILC2s) can be rapidly activated and represent an early innate source of IL-5 and IL-13. Here, we used a house dust mite (HDM)-driven asthma mouse model to study the induction of ILC2s in allergic airway inflammation. In BALF, lungs, and lymph nodes, ILC2 activation is critically dependent on prior sensitization with HDM. Importantly, T cells are required for ILC2 induction, whereby T-cell activation precedes ILC2 induction. During HDM-driven allergic airway inflammation the accumulation of ILC2s in BALF is IL-33 independent, although infiltrating ILC2s produce less cytokines in Il33(-/-) mice. Transfer of in vitro polarized OVA-specific OT-II Th2 cells alone or in combination with Th17 cells followed by OVA and HDM challenge is not sufficient to induce ILC2, despite significant eosinophilic inflammation and T-cell activation. In this asthma model, ILC2s are therefore not an early source of Th2 cytokines, but rather contribute to type 2 inflammation in which Th2 cells play a key role. Taken together, ILC2 induction in HDM-mediated allergic airway inflammation in mice critically depends on activation of T cells.

Extended Tumor Control after Dendritic Cell Vaccination with Low-Dose Cyclophosphamide as Adjuvant Treatment in Patients with Malignant Pleural Mesothelioma.

RATIONALE: We demonstrated previously that autologous tumor lysate-pulsed dendritic cell-based immunotherapy in patients with malignant pleural mesothelioma is feasible, well-tolerated, and capable of inducing immunologic responses against tumor cells. In our murine model, we found that reduction of regulatory T cells with metronomic cyclophosphamide increased the efficacy of immunotherapy. OBJECTIVES: To assess the decrease in number of peripheral blood regulatory T cells during combination therapy of low-dose cyclophosphamide and dendritic cell immunotherapy and determine the induction of immunologic responses with this treatment in patients with mesothelioma. METHODS: Ten patients with malignant pleural mesothelioma received metronomic cyclophosphamide and dendritic cell-based immunotherapy. During the treatment, peripheral blood mononuclear cells were analyzed for regulatory T cells and immunologic responses. MEASUREMENTS AND MAIN RESULTS: Administration of dendritic cells pulsed with autologous tumor lysate combined with cyclophosphamide in patients with mesothelioma was safe, the only side effect being moderate fever. Dendritic cell vaccination combined with cyclophosphamide resulted in radiographic disease control in 8 of the 10 patients. Overall survival was promising, with 7 out of 10 patients having a survival of greater than or equal to 24 months and two patients still alive after 50 and 66 months. Low-dose cyclophosphamide reduced the percentage of regulatory T cells of total CD4 cells in peripheral blood from 9.43 (range, 4.34-26.10) to 4.51 (range, 0.27-10.30) after 7 days of cyclophosphamide treatment (P = 0.02). CONCLUSIONS: Consolidation therapy with autologous tumor lysate-pulsed dendritic cell-based therapy and simultaneously reducing the tumor-induced immune suppression is well-tolerated and shows signs of clinical activity in patients with mesothelioma. Clinical trial registered with www.clinicaltrials.gov (NCT 01241682).

Impaired survival of regulatory T cells in pulmonary sarcoidosis.

BACKGROUND: Impaired regulatory T cell (Treg) function is thought to contribute to ongoing inflammatory responses in sarcoidosis, but underlying mechanisms remain unclear. Moreover, it is not known if increased apoptotic susceptibility of Tregs may contribute to an impaired immunosuppressive function in sarcoidosis. Therefore, the aim of this study is to analyze proportions, phenotype, survival, and apoptotic susceptibility of Tregs in sarcoidosis. METHODS: Patients with pulmonary sarcoidosis (n = 58) were included at time of diagnosis. Tregs were analyzed in broncho-alveolar lavage fluid and peripheral blood of patients and healthy controls (HC). RESULTS: In sarcoidosis patients no evidence was found for a relative deficit of Tregs, neither locally nor systemically. Rather, increased proportions of circulating Tregs were observed, most prominently in patients developing chronic disease. Sarcoidosis circulating Tregs displayed adequate expression of FoxP3, CD25 and CTLA4. Remarkably, in sarcoidosis enhanced CD95 expression on circulating activated CD45RO(+) Tregs was observed compared with HC, and proportions of these cells were significantly increased. Specifically sarcoidosis Tregs--but not Th cells--showed impaired survival compared with HC. Finally, CD95L-mediated apoptosis was enhanced in sarcoidosis Tregs. CONCLUSION: In untreated patients with active pulmonary sarcoidosis, Tregs show impaired survival and enhanced apoptotic susceptibility towards CD95L. Increased apoptosis likely contributes to the insufficient immunosuppressive function of sarcoidosis Tregs. Further research into this field will help determine whether improvement of Treg survival holds a promising new therapeutic approach for chronic sarcoidosis patients.

Immunoglobulin-like transcript 3 is expressed by myeloid-derived suppressor cells and correlates with survival in patients with non-small cell lung cancer.

Myeloid-derived suppressor cells (MDSCs) play an important role in immune suppression and accumulate under pathologic conditions such as cancer and chronic inflammation. They comprise a heterogeneous population of immature myeloid cells that exert their immunosuppressive function via a variety of mechanisms. Immunoglobulin-like transcript 3 (ILT3) is a receptor containing immunoreceptor tyrosine-based inhibition motifs (ITIMs) that can be expressed on antigen-presenting cells and is an important regulator of dendritic cell tolerance. ILT3 exists in a membrane-bound and a soluble form and can interact with a yet unidentified ligand on T cells and thereby induce T-cell anergy, regulatory T cells, or T suppressor cells. In this study, we analyzed freshly isolated peripheral blood mononuclear cells (PBMCs) of 105 patients with non-small cell lung cancer and 20 healthy controls and demonstrated for the first time that ILT3 is expressed on MDSCs. We show that increased levels of circulating MDSCs correlate with reduced survival. On the basis of ILT3 cell surface expression, an ILT3low and ILT3high population of polymorphonuclear (PMN)-MDSCs could be distinguished. Interestingly, in line with the immunosuppressive function of ILT3 on dendritic cells, patients with an increased proportion of PMN-MDSCs and an increased fraction of the ILT3high subset had a shorter median survival than patients with elevated PMN-MDSC and a smaller ILT3high fraction. No correlation between the ILT3high subset and other immune variables was found. ILT3 expressed on MDSCs might reflect a previously unknown mechanism by which this cell population induces immune suppression and could therefore be an attractive target for immune intervention.

[Surgical management of bronchiectasis]. / Chirurgische therapie van bronchiëctasieën.

Exacerbations of bronchiectasis can result in a decline in lung function, a poorer prognosis and a reduction in quality of life. Three female patients aged 57, 41 and 40 presented with recurrent exacerbations of bronchiectasis despite optimal conservative and antibiotic (maintenance) treatment. In one patient the underlying cause of the bronchiectasis could not be identified; in the other two patients there was a post infectious cause. Surgical procedures were performed on account of the presence of localised bronchiectasis. No major complications were observed. All three patients experienced an impressive reduction in symptoms and exacerbations. Moreover, there was only a slight decline in lung function in two patients and an improvement in lung function in one patient. In patients with localised bronchiectasis, recurrent exacerbations and persistent symptoms despite optimal conservative and antibiotic treatment, surgical resection of affected areas could reduce the number of exacerbations and improve quality of life.

Intratumoral macrophage phenotype and CD8+ T lymphocytes as potential tools to predict local tumor outgrowth at the intervention site in malignant pleural mesothelioma.

OBJECTIVES: In patients with malignant pleural mesothelioma (MPM), local tumor outgrowth (LTO) after invasive procedures is a well-known complication. Currently, no biomarker is available to predict the occurrence of LTO. This study aims to investigate whether the tumor macrophage infiltration and phenotype of and/or the infiltration of CD8+ T-cells predicts LTO. MATERIALS AND METHODS: Ten mesothelioma patients who developed LTO were clinically and pathologically matched with 10 non-LTO mesothelioma patients. Immunohistochemistry was performed on diagnostic biopsies to determine the total TAM (CD68), the M2 TAM (CD163) and CD8+ T-cell count (CD8). RESULTS: The mean M2/total TAM ratio differed between the two groups: 0.90±0.09 in the LTO group versus 0.63±0.09 in patients without LTO (p<0.001). In addition, the mean CD8+ T-cell count was significantly different between the two groups: 30 per 0.025 cm2 (range 2-60) in the LTO group and 140 per 0.025 cm2 (range 23-314) in the patients without LTO (p<0.01). CONCLUSION: This study shows that patients who develop LTO after a local intervention have a higher M2/total TAM ratio and lower CD8+ cell count at diagnosis compared to patients who did not develop this outgrowth. We propose that the M2/total TAM ratio and the CD8+ T-cell amount are potential tools to predict which MPM patients are prone to develop LTO.

Occurrence of virus-induced COPD exacerbations during four seasons.

In this study, we investigated the occurrence of viral infections in acute exacerbations of chronic obstructive pulmonary disease (COPD) during four seasons. Viral infections were detected by the use of real-time reverse transcriptase polymerase chain reaction on pharyngeal swabs. During a 12-month period pharyngeal swabs were obtained in 136 exacerbations of 63 patients. In 35 exacerbations (25.7%) a viral infection was detected. Most viral infections occurred in the winter (n = 14, 40.0%), followed by summer (n = 9, 25.7%), autumn (n = 6, 17.1%), and spring (n = 6, 17.1%). Rhinovirus was the most frequently isolated virus (n = 19, 51.4%), followed by respiratory syncytial virus (n = 6, 16.2%), human metapneumovirus (n = 5, 13.5%), influenza A (n = 4, 10.8%), parainfluenza 4 (n = 2, 5.4%), and parainfluenza 3 (n = 1, 2.7%). This study showed that virus-induced COPD exacerbations occur in all four seasons with a peak in the winter months. However, the distribution of rhinovirus infections showed a different pattern, with most infections occurring in July.

Ratio of intratumoral macrophage phenotypes is a prognostic factor in epithelioid malignant pleural mesothelioma.

HYPOTHESIS: The tumor micro-environment and especially the different macrophage phenotypes appear to be of great influence on the behavior of multiple tumor types. M1 skewed macrophages possess anti-tumoral capacities, while the M2 polarized macrophages have pro-tumoral capacities. We analyzed if the macrophage count and the M2 to total macrophage ratio is a discriminative marker for outcome after surgery in malignant pleural mesothelioma (MPM) and studied the prognostic value of these immunological cells. METHODS: 8 MPM patients who received induction chemotherapy and surgical treatment were matched on age, sex, tumor histology, TNM stage and EORTC score with 8 patients who received chemotherapy only. CD8 positive T-cells and the total macrophage count, using the CD68 pan-macrophage marker, and CD163 positive M2 macrophage count were determined in tumor specimens prior to treatment. RESULTS: The number of CD68 and CD163 cells was comparable between the surgery and the non-surgery group, and was not related to overall survival (OS) in both the surgery and non-surgery group. However, the CD163/CD68 ratio did correlate with OS in both in the total patient group (Pearson r -0.72, p<0.05). No correlation between the number of CD8 cells and prognosis was found. CONCLUSIONS: The total number of macrophages in tumor tissue did not correlate with OS in both groups, however, the CD163/CD68 ratio correlates with OS in the total patient group. Our data revealed that the CD163/CD68 ratio is a potential prognostic marker in epithelioid mesothelioma patients independent of treatment but cannot be used as a predictive marker for outcome after surgery.

Peptides from the variable region of specific antibodies are shared among lung cancer patients.

Late diagnosis of lung cancer is still the main reason for high mortality rates in lung cancer. Lung cancer is a heterogeneous disease which induces an immune response to different tumor antigens. Several methods for searching autoantibodies have been described that are based on known purified antigen panels. The aim of our study is to find evidence that parts of the antigen-binding-domain of antibodies are shared among lung cancer patients. This was investigated by a novel approach based on sequencing antigen-binding-fragments (Fab) of immunoglobulins using proteomic techniques without the need of previously known antigen panels. From serum of 93 participants of the NELSON trial IgG was isolated and subsequently digested into Fab and Fc. Fab was purified from the digested mixture by SDS-PAGE. The Fab containing gel-bands were excised, tryptic digested and measured on a nano-LC-Orbitrap-Mass-spectrometry system. Multivariate analysis of the mass spectrometry data by linear canonical discriminant analysis combined with stepwise logistic regression resulted in a 12-antibody-peptide model which was able to distinguish lung cancer patients from controls in a high risk population with a sensitivity of 84% and specificity of 90%. With our Fab-purification combined Orbitrap-mass-spectrometry approach, we found peptides from the variable-parts of antibodies which are shared among lung cancer patients.

Azithromycin maintenance treatment in patients with frequent exacerbations of chronic obstructive pulmonary disease (COLUMBUS): a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Macrolide resistance is an increasing problem; there is therefore debate about when to implement maintenance treatment with macrolides in patients with chronic obstructive pulmonary disease (COPD). We aimed to investigate whether patients with COPD who had received treatment for three or more exacerbations in the previous year would have a decrease in exacerbation rate when maintenance treatment with azithromycin was added to standard care. METHODS: We did a randomised, double-blind, placebo-controlled, single-centre trial in The Netherlands between May 19, 2010, and June 18, 2013. Patients (≥18 years) with a diagnosis of COPD who had received treatment for three or more exacerbations in the previous year were randomly assigned, via a computer-generated randomisation sequence with permuted block sizes of ten, to receive 500 mg azithromycin or placebo three times a week for 12 months. Randomisation was stratified by use of long-term, low-dose prednisolone (≤10 mg daily). Patients and investigators were masked to group allocation. The primary endpoint was rate of exacerbations of COPD in the year of treatment. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00985244. FINDINGS: We randomly assigned 92 patients to the azithromycin group (n=47) or the placebo group (n=45), of whom 41 (87%) versus 36 (80%) completed the study. We recorded 84 exacerbations in patients in the azithromycin group compared with 129 in those in the placebo group. The unadjusted exacerbation rate per patient per year was 1·94 (95% CI 1·50-2·52) for the azithromycin group and 3·22 (2·62-3·97) for the placebo group. After adjustment, azithromycin resulted in a significant reduction in the exacerbation rate versus placebo (0·58, 95% CI 0·42-0·79; p=0·001). Three (6%) patients in the azithromycin group reported serious adverse events compared with five (11%) in the placebo group. During follow-up, the most common adverse event was diarrhoea in the azithromycin group (nine [19%] patients vs one [2%] in the placebo group; p=0·015). INTERPRETATION: Maintenance treatment with azithromycin significantly decreased the exacerbation rate compared with placebo and should therefore be considered for use in patients with COPD who have the frequent exacerbator phenotype and are refractory to standard care. FUNDING: SoLong Trust.