Operational classification of cutaneous squamous cell carcinomas based on unsupervised clustering of real cases by experts.

BACKGROUND: There is currently no staging system for cutaneous squamous cell carcinoma (cSCC) that is adapted to decision-making and universally used. Experts have unconscious ability to simplify the heterogeneity of clinical situations into a few relevant groups to drive their therapeutic decisions. Therefore, we have used unsupervised clustering of real cases by experts to generate an operational classification of cSCCs, an approach that was successful for basal cell carcinomas. OBJECTIVE: To generate a consensual and operational classification of cSCCs. METHOD: Unsupervised independent clustering of 248 cases of cSCCs considered difficult-to-treat. Eighteen international experts from different specialties classified these cases into what they considered homogeneous clusters useful for management, each with freedom regarding clustering criteria. Convergences and divergences between clustering were analysed using a similarity matrix, the K-mean approach and the average silhouette method. Mathematical modelling was used to look for the best consensual clustering. The operability of the derived classification was validated on 23 new practitioners. RESULTS: Despite the high heterogeneity of the clinical cases, a mathematical consensus was observed. It was best represented by a partition into five clusters, which appeared a posteriori to describe different clinical scenarios. Applicability of this classification was shown by a good concordance (94%) in the allocation of cases between the new practitioners and the 18 experts. An additional group of easy-to-treat cSCC was included, resulting in a six-group final classification: easy-to-treat/complex to treat due to tumour and/or patient characteristics/multiple/locally advanced/regional disease/visceral metastases. CONCLUSION: Given the methodology based on the convergence of unguided intuitive clustering of cases by experts, this new classification is relevant for clinical practice. It does not compete with staging systems, but they may complement each other, whether the objective is to select the best therapeutic approach in tumour boards or to design homogeneous groups for trials.

Immune checkpoint inhibitor-induced neurotoxicity is not associated with seroprevalence of neurotropic infections.

BACKGROUND: Immune checkpoint inhibitors (ICI) substantially improve outcome for patients with cancer. However, the majority of patients develops immune-related adverse events (irAEs), which can be persistent and significantly reduce quality of life. Neurological irAEs occur in 1-5% of patients and can induce severe, permanent sequelae or even be fatal. In order to improve the diagnosis and treatment of neurological irAEs and to better understand their pathogenesis, we assessed whether previous neurotropic infections are associated with neurological irAEs. METHODS: Neurotropic infections that might predispose to ICI-induced neurological irAEs were analyzed in 61 melanoma patients from 3 countries, the Netherlands, Australia and Germany, including 24 patients with neurotoxicity and 37 control patients. In total, 14 viral, 6 bacterial, and 1 protozoal infections previously reported to trigger neurological pathologies were assessed using routine serology testing. The Dutch and Australian cohorts (NL) included pre-treatment plasma samples of patients treated with neoadjuvant ICI therapy (OpACIN-neo and PRADO trials; NCT02977052). In the Dutch/Australian cohort a total of 11 patients with neurological irAEs were compared to 27 control patients (patients without neurological irAEs). The German cohort (LMU) consisted of serum samples of 13 patients with neurological irAE and 10 control patients without any documented irAE under ICI therapy. RESULTS: The association of neurological irAEs with 21 possible preceding infections was assessed by measuring specific antibodies against investigated agents. The seroprevalence of all the tested viral (cytomegalovirus, Epstein-Barr-Virus, varicella-zoster virus, measles, rubella, influenza A and B, human herpes virus 6 and 7, herpes simplex virus 1 and 2, parvovirus B19, hepatitis A and E and human T-lymphotropic virus type 1 and 2), bacterial (Borrelia burgdorferi sensu lato, Campylobacter jejuni, Mycoplasma pneumoniae, Coxiella burnetti, Helicobacter pylori, Yersinia enterocolitica and Y. pseudotuberculosis) and protozoal (Toxoplasma gondii) infections was similar for patients who developed neurological irAEs as compared to control patients. Thus, the analysis provided no evidence for an association of described agents tested for seroprevalence with ICI induced neurotoxicity. CONCLUSION: Previous viral, bacterial and protozoal neurotropic infections appear not to be associated with the development of neurological irAEs in melanoma patients who underwent therapy with ICI across 3 countries. Further efforts are needed to unravel the factors underlying neurological irAEs in order to identify risk factors for these toxicities, especially with the increasing use of ICI in earlier stage disease.

[Neurological side effects of checkpoint inhibitors]. / Neurologische Nebenwirkungen von Checkpoint-Inhibitoren.

BACKGROUND: In recent years the treatment of many tumor entities has been revolutionized by the use of modern immunotherapies with checkpoint inhibitors; however, good response rates are contrasted by many immune-mediated side effects. Neurological immune-mediated side effects are rare but often severe complications of checkpoint inhibitor treatment. METHOD: A systematic search in the PubMed and Web of Sciences databases was carried out for case reports and studies on neurological side effects during checkpoint inhibitor treatment. RESULTS: A total of 42 articles on neurological side effects of checkpoint inhibitors with a total of 85 reported cases could be identified. The most frequently reported neurological side effects were myopathies, neuropathies, diseases of the neuromuscular endplates and encephalitides. Among those, encephalitides and myopathies with accompanying myocarditis were associated with the highest morbidity and mortality. CONCLUSION: Against the background of a rapidly increasing use of checkpoint inhibitors, this article provides an overview of currently available reports on the clinical courses of neurological side effects. Controlled studies on the treatment of neurological side effects are lacking. From case studies it can be assumed that early steroid treatment increases the probability of a complete remission of neurological symptoms. Typical symptom constellations must therefore be rapidly recognized and an immunosuppressive treatment must be initiated.

Effective anti-programmed death-1 therapy in a SUFU-mutated patient with Gorlin-Goltz syndrome.

We present the case of a 77-year-old male patient with more than 50 basal cell carcinomas on the head and upper trunk. The patient did not respond to several lines of treatment, including surgery, imiquimod, retinoids, itraconazole and therapy with the hedgehog inhibitor vismodegib. The patient responded well to off-label therapy with the anti-programmed death-1 antibody pembrolizumab after four infusions.

Adjuvant treatment with pegylated interferon α-2a versus low-dose interferon α-2a in patients with high-risk melanoma: a randomized phase III DeCOG trial.

BACKGROUND: Adjuvant treatment with interferon (IFN)-α-2a improved disease-free survival (DFS) and showed a trend for improving overall survival (OS) in melanoma. This trial was designed to examine whether PEG-IFN is superior to IFN with regard to distant metastasis-free survival (DMFS), DFS and OS. PATIENTS AND METHODS: In this multicenter, open-label, prospective randomized phase III trial, patients with resected cutaneous melanoma stage IIA(T3a)-IIIB (AJCC 2002) were randomized to receive PEG-IFN (180 µg subcutaneously 1×/week; 24 months) or IFN α-2a (3MIU subcutaneously 3×/week; 24 months). Randomization was stratified for stage, number of metastatic nodes, age and previous IFN treatment. The primary end point was DMFS; secondary end points were OS, DFS, quality of life (QoL) and tolerability. RESULTS: A total of 909 patients were enrolled (451 PEG-IFN versus 458 IFN). Neither 5-year DMFS [PEG-IFN 61.0% versus IFN 67.3%; hazard ratio (HR) 1.16, P = 0.21] nor 5-year OS (PEG-IFN 73.2% versus IFN 75.2%; HR 1.05, P = 0.70) nor 5-year DFS (PEG-IFN 57.3% versus IFN 60.9%; HR 1.09, P = 0.40) showed significant differences. Subgroup analyses in patients ± ulcerated primaries and of different tumor stages did not find differences in DMFS, OS or DFS between the treatment groups. One hundred and eighteen patients (26.2%) in the PEG-IFN and 61 patients (13.3%) in the IFN population did not receive the full dosage and length of treatment due to adverse events (P < 0.001). Leukopenia and elevation of liver enzymes were more common in the PEG-IFN arm (56% versus 23.5% LCP; 19.1% versus 9.4% AST; 33.0% versus 16.5% ALT). QoL was identical for nearly all domains. CONCLUSION: PEG-IFN did not improve the outcome over IFN. A higher percentage of patients under PEG-IFN discontinued treatment due to toxicity. CLINICAL TRIALSGOV IDENTIFIER: NCT00204529.

A multicenter DeCOG study on predictors of vemurafenib therapy outcome in melanoma: pretreatment impacts survival.

BACKGROUND: Kinase inhibitors targeting the BRAF V600 mutation have become standard in the treatment of metastatic melanoma. Albeit in wide clinical use, the patterns associated with therapy outcome are not fully elucidated. The present study was aimed to identify predictive factors of therapy response and survival under the BRAF inhibitor vemurafenib. PATIENTS AND METHODS: This multicenter retrospective study analyzed patient, tumor, and pretreatment characteristics collected in BRAF V600-mutated stage IV melanoma patients before single-agent therapy with the BRAF inhibitor vemurafenib. RESULTS: A total of 300 patients from 14 centers were included into this study with a median follow-up time of 13.0 months. Median progression-free survival (PFS) was 5.1 months; median overall survival (OS) was 7.6 months. Best response under vemurafenib was associated with serum lactate dehydrogenase (LDH; ≤ versus >upper normal limit; P = 0.0000001), Eastern Cooperative Oncology Group (ECOG) overall performance status (OPS) (0 versus ≥ 1; P = 0.00089), and BRAF mutation subtype (V600E versus V600K; P = 0.016). Multivariate analysis identified ECOG OPS ≥ 1 [hazard ratio (HR) = 1.88; P = 0.00005], immunotherapy pretreatment (HR = 0.53; P = 0.0067), elevated serum LDH (HR = 1.45; P = 0.012), age >55 years (HR = 0.72; P = 0.019), and chemotherapy pretreatment (HR = 1.39; P = 0.036) as independent predictors of PFS. For OS, elevated serum LDH (HR = 1.99; P = 0.00012), ECOG OPS ≥ 1 (HR = 1.90; P = 0.00063), age >55 years (HR = 0.65; P = 0.011), kinase inhibitor pretreatment (HR = 1.86; P = 0.014), immunotherapy pretreatment (HR = 0.57; P = 0.025), chemotherapy pretreatment (HR = 2.17; P = 0.039), and male gender (HR = 0.70; 95% confidence interval 0.50-0.98; P = 0.039) were found as predictors. CONCLUSION: Our data demonstrate that the type of pretreatment strongly influences the outcome of vemurafenib therapy, with a precedent immunotherapy showing a positive, and a prior chemotherapy and kinase inhibitors showing a negative impact on survival, respectively. Moreover, we show that the patient's OPS, serum LDH, age, and gender independently impact vemurafenib therapy outcome. These findings should be taken into account for the future design of therapy sequencing in BRAF V600 mutation-positive melanoma patients.

Radiosensitization by BRAF inhibitor therapy-mechanism and frequency of toxicity in melanoma patients.

BACKGROUND: Recent evidence suggests that ionizing radiation may be associated with unexpected side-effects in melanoma patients treated with concomitant BRAF inhibitors. A large multicenter analysis was carried out to generate reliable safety data and elucidate the mechanism. METHODS: A total of 161 melanoma patients from 11 European skin cancer centers were evaluated for acute and late toxicity, of whom 70 consecutive patients received 86 series of radiotherapy with concomitant BRAF inhibitor therapy. To further characterize and quantify a possible radiosensitization by BRAF inhibitors, blood samples of 35 melanoma patients were used for individual radiosensitivity testing by fluorescence in situ hybridization of chromosomal breaks after ex vivo irradiation. RESULTS: With radiotherapy and concomitant BRAF inhibitor therapy the rate of acute radiodermatitis ≥2° was 36% and follicular cystic proliferation was seen in 13% of all radiotherapies. Non-skin toxicities included hearing disorders (4%) and dysphagia (2%). Following whole-brain radiotherapy, rates of radiodermatitis ≥2° were 44% and 8% (P < 0.001) for patients with and without BRAF inhibitor therapy, respectively. Concomitant treatment with vemurafenib induced acute radiodermatitis ≥2° more frequently than treatment with dabrafenib (40% versus 26%, P = 0.07). In line with these findings, analysis of chromosomal breaks ex vivo indicated significantly increased radiosensitivity for patients under vemurafenib (P = 0.004) and for patients switched from vemurafenib to dabrafenib (P = 0.002), but not for patients on dabrafenib only. No toxicities were reported after stereotactic treatment. CONCLUSION: Radiotherapy with concomitant BRAF inhibitor therapy is feasible with an acceptable increase in toxicity. Vemurafenib is a more potent radiosensitizer than dabrafenib.

Clinical relevance is associated with allergen-specific wheal size in skin prick testing.

BACKGROUND: Within a large prospective study, the Global Asthma and Allergy European Network (GA(2) LEN) has collected skin prick test (SPT) data throughout Europe to make recommendations for SPT in clinical settings. OBJECTIVE: To improve clinical interpretation of SPT results for inhalant allergens by providing quantitative decision points. METHODS: The GA(2) LEN SPT study with 3068 valid data sets was used to investigate the relationship between SPT results and patient-reported clinical relevance for each of the 18 inhalant allergens as well as SPT wheal size and physician-diagnosed allergy (rhinitis, asthma, atopic dermatitis, food allergy). The effects of age, gender, and geographical area on SPT results were assessed. For each allergen, the wheal size in mm with an 80% positive predictive value (PPV) for being clinically relevant was calculated. RESULTS: Depending on the allergen, from 40% (blatella) to 87-89% (grass, mites) of the positive SPT reactions (wheal size ≥ 3 mm) were associated with patient-reported clinical symptoms when exposed to the respective allergen. The risk of allergic symptoms increased significantly with larger wheal sizes for 17 of the 18 allergens tested. Children with positive SPT reactions had a smaller risk of sensitizations being clinically relevant compared with adults. The 80% PPV varied from 3 to 10 mm depending on the allergen. CONCLUSION: These 'reading keys' for 18 inhalant allergens can help interpret SPT results with respect to their clinical significance. A SPT form with the standard allergens including mm decision points for each allergen is offered for clinical use.

Mutation landscape in melanoma patients clinical implications of heterogeneity of BRAF mutations.

BACKGROUND: The detection of V600E BRAF mutations has fundamental clinical consequences as the treatment option with BRAF inhibitors such as vemurafenib or dabrafenib yields response rates of ~48%. Heterogeneity with respect to BRAF mutation in different metastases has been described in single cases. As this has important implications for the determination of BRAF status and treatment of patients, it is essential to acquire more data. METHODS: A total of 300 tumour samples from 187 melanoma patients were analysed for BRAF mutations by pyrosequencing. Equivocal results were confirmed by capillary sequencing. Clinical data with respect to melanoma type, tumour site and survival were summarised for 53 patients with multiple analysed tumour samples (2-13 per patient). RESULTS: BRAF mutations were found in 84 patients (44.9%) and 144 tumour samples (48%) with BRAF mutations in 45.5% of primary tumours and 51.3% of metastases, respectively. In 10 out of 53 patients (18.9%) where multiple samples were analysed results were discordant with respect to mutation findings with wild-type and mutated tumours in the same patient. Mutations did not appear more frequently over the course of disease nor was its occurrence associated with a specific localisation of metastases. CONCLUSION: As heterogeneity with respect to BRAF mutation status is detected in melanoma patients, subsequent testing of initially wild-type patients can yield different results and thus make BRAF inhibitor therapy accessible. The role of heterogeneity in testing and for clinical response to therapy with a BRAF inhibitor needs to be further investigated.

Rare BRAF mutations in melanoma patients: implications for molecular testing in clinical practice.

BACKGROUND: The detection of V600E BRAF mutation in melanoma is fundamental since here BRAF inhibitors represent an effective treatment. Non-V600E BRAF mutations that may also respond are not detected by certain screening methods. Thus, knowledge about detection of these mutations is needed. METHODS: A total of 276 tumour samples from 174 melanoma patients were investigated for BRAF mutations by pyrosequencing. Rare mutations were confirmed by capillary sequencing and compared with findings from COBAS test and immunohistochemistry using a novel BRAF antibody. Melanoma type, localisation, and survival were summarised. RESULTS: BRAF mutations were found in 43% of patients (124 tumours in 75 patients). Among those, 14 patients (18.7%) exhibited rare mutations. The V600EK601del and V600DK601del mutations have never been described before in melanoma. Furthermore, V600K, V600E2, and V600D, V600G, V600R, and L597S mutations were detected. Mutations were not detected by COBAS test in 7 out of these 14 patients and immunohistochemistry only reliably detected patients with the V600E2 and V600EK601del mutation. CONCLUSION: Accurate diagnosis of rare BRAF mutations is crucial. We show that pyrosequencing is accurate, highly sensitive, reliable, and time saving to detect rare BRAF mutations. Missing these rare variant mutations would exclude a subset of patients from available effective BRAF-targeting therapy.

Preferences of German and Swiss melanoma patients for toxicities versus melanoma recurrence during adjuvant treatment (GERMELATOX-A-trial).

PURPOSE: Adjuvant treatment with immune checkpoint inhibitors like PD1-antibodies (ICI) ± CTLA4-antibodies (cICI) or targeted therapy with BRAF/MEK inhibitors (TT) in high-risk melanoma patients demonstrate a significant improvement in disease-free survival (DFS). Due to specific side effects, the choice of treatment is very often driven by the risk for toxicity. This study addressed for the first time in a multicenter setting the attitudes and preferences of melanoma patients for adjuvant treatment with (c)ICI and TT. METHODS: In this study ("GERMELATOX-A"), 136 low-risk melanoma patients from 11 skin cancer centers were asked to rate side effect scenarios typical for each (c)ICI and TT with mild-to-moderate or severe toxicity and melanoma recurrence leading to cancer death. We asked patients about the reduction in melanoma relapse and the survival increase at 5 years they would require to tolerate defined side-effects. RESULTS: By VAS, patients on average valued melanoma relapse worse than all scenarios of side-effects during treatment with (c)ICI or TT. In case of severe side effects, patients required a 15% higher rate of DFS at 5 years for (c)ICI (80%) compared to TT (65%). For survival, patients required an increase of 5-10% for melanoma survival during (c)ICI (85%/80%) compared to TT (75%). CONCLUSION: Our study demonstrated a pronounced variation of patient preferences for toxicity and outcomes and a clear preference for TT. As adjuvant melanoma treatment with (c)ICI and TT will be increasingly implemented in earlier stages, precise knowledge of the patient perspective can be helpful for decision making.

Cancer of unknown primary (CUP) through the lens of precision oncology: a single institution perspective.

PURPOSE: For patients with cancer of unknown primary (CUP), treatment options are limited. Precision oncology, the interplay of comprehensive genomic profiling (CGP) and targeted therapies, aims to offer additional treatment options to patients with advanced and hard-to-treat cancers. We aimed to highlight the use of a molecular tumor board (MTB) in the therapeutic management of CUP patients. METHODS: In this single-center observational study, CUP patients, presented to the MTB of the Comprehensive Cancer Center Munich LMU, a tertiary care center, were analyzed retrospectively. Descriptive statistics were applied to describe relevant findings. RESULTS: Between June 2016 and February 2022, 61 patients with unfavorable CUP were presented to the MTB, detected clinically relevant variants in 74% (45/61) of patients, of which 64% (29/45) led to therapeutic recommendation. In four out of 29 patients (14%), the treatment recommendations were implemented, unfortunately without resulting in clinical benefit. Reasons for not following the therapeutic recommendation were mainly caused by the physicians' choice of another therapy (9/25, 36%), especially in the context of worsening of general condition, lost to follow-up (7/25, 28%) and death (6/25, 24%). CONCLUSION: CGP and subsequent presentation to a molecular tumor board led to a high rate of therapeutic recommendations in patients with CUP. Recommendations were only implemented at a low rate; however, late GCP diagnostic and, respectively, MTB referral were found more frequent for the patients with implemented treatment. This contrast underscores the need for early implementation of CGP into the management of CUP patients.

Practical guide to skin prick tests in allergy to aeroallergens.

This pocket guide is the result of a consensus reached between members of the Global Allergy and Asthma European Network (GA(2) LEN) and Allergic Rhinitis and its Impact on Asthma (ARIA). The aim of the current pocket guide is to offer a comprehensive set of recommendations on the use of skin prick tests in allergic rhinitis-conjunctivitis and asthma in daily practice. This pocket guide is meant to give simple answers to the most frequent questions raised by practitioners in Europe, including 'practicing allergists', general practitioners and any other physicians with special interest in the management of allergic diseases. It is not a long or detailed scientific review of the topic. However, the recommendations in this pocket guide were compiled following an in-depth review of existing guidelines and publications, including the 1993 European Academy of Allergy and Clinical Immunology position paper, the 2001 ARIA document and the ARIA update 2008 (prepared in collaboration with GA(2) LEN). The recommendations cover skin test methodology and interpretation, allergen extracts to be used, as well as indications in a variety of settings including paediatrics and developing countries.

Is drug allergy less prevalent than previously assumed? A 5-year analysis.

BACKGROUND: Rashes are a frequent conundrum in clinical practice as they may be reactive, drug induced or disease specific. Identification of the culprit drug is important as re-exposure may be harmful or even life-threatening and unnecessary avoidance of 'innocent' drugs leads to limitations of treatment options. OBJECTIVE: To objectify the cause of suspected cutaneous drug reactions in a large patient population. METHOD: Over 5years (2006-10), 612 patients with suspected cutaneous drug reactions were evaluated. Histology was assessed. About 200 patients were invited for complete work-up with skin tests (prick/intracutaneous testing and scratch/patch as indicated) and, if necessary, lymphocyte transformation tests (LTT). In special cases, drug provocation tests were conducted. RESULTS: A total number of 141 cases with suspected drug reaction underwent full work-up (age 6-86years; 75% female, 25% male). In 107 cases (76%) a drug was identified whereas 34 (24%) were reactive rashes or had other causes. Mostly, cutaneous drug reactions were maculopapular rashes, urticaria/angio-oedema; less frequently, acute generalized exanthematous pustulosis, drug reaction with eosinophilia and systemic symptoms, systemic drug-related intertriginous and flexural exanthema, toxic epidermal necrolysis and fixed drug eruptions were present. Of all the cutaneous drug reactions investigated, 39·8% were caused by antibiotics, 21·2% by anti-inflammatories, 7·6% by contrast media and 31·4% by others (oral antidiabetics, antimycotics, antipsychotics, antiepileptics and others). CONCLUSION: Clinical assessment overestimates the role of drug allergies in cutaneous reactions. Assessment of suspected drug reactions can be greatly improved by thorough evaluation including dermatological and allergological work-up with skin testing and assays such as LTT.

Contact dermatitis induced by glatiramer acetate.

Glatiramer acetate (Copaxone(®)) is an immunomodulatory polypeptide used in patients with relapsing-remitting multiple sclerosis. It represents a safe treatment option with mild side effects. In this study, we look at a 39-year-old woman who received glatiramer acetate as subcutaneous injections for two months and developed contact dermatitis. The drug had to be stopped, and treatment with topical prednisone was initiated. Prick/scratch testing was negative but the lymphocyte transformation test was highly positive for glatiramer acetate. This is the first report on contact dermatitis induced by glatiramer acetate injections. The treatment consisted of local topical steroids and cessation of the drug.

In vivo induction of interferon gamma expression in grey horses with metastatic melanoma resulting from direct injection of plasmid DNA coding for equine interleukin 12.

Whole blood pharmacokinetics of intratumourally injected naked plasmid DNA coding for equine Interleukin 12 (IL-12) was assessed as a means of in vivo gene transfer in the treatment of melanoma in grey horses. The expression of induced interferon gamma (IFN-g) was evaluated in order to determine the pharmacodynamic properties of in vivo gene transduction. Seven grey horses bearing melanoma were injected intratumourally with 250 µg naked plasmid DNA coding for IL-12. Peripheral blood and biopsies from the injection site were taken at 13 time points until day 14 post injection (p.i.). Samples were analysed using quantitative real-time PCR. Plasmid DNA was quantified in blood samples and mRNA expression for IFN-g in tissue samples. Plasmid DNA showed fast elimination kinetics with more than 99 % of the plasmid disappearing within 36 hours. IFN-g expression increased quickly after IL-12 plasmid injection, but varied between individual horses. Intratumoural injection of plasmid DNA is a feasible method for inducing transgene expression in vivo. Biological activity of the transgene IL-12 was confirmed by measuring expression of IFN-g.

Establishing a standardized quality management system for the European Health Network GA2LEN.

BACKGROUND: Quality management is increasingly important in clinical practice. The Global Allergy and Asthma European Network (GA(2)LEN) is a network of clinical and scientific excellence with originally 25 allergy centres in 16 European countries, a scientific society (European Academy of Allergology and Clinical Immunology), and a patient organization (European Federation of Allergy and Airways Diseases Patients' Associations). Although some allergy centres adhere to internal quality criteria, the implementation of a standardized quality management system for allergy centres across Europe was lacking. OBJECTIVES: To implement standardized quality criteria among allergy centres organized within GA(2)LEN and thus ensure equal standards of diagnosis and care as well as to establish a culture of continuous quality improvement. METHODS: Quality criteria covering, e.g., diagnostic and therapeutic procedures, and emergency preparedness to assure patient safety were developed and agreed upon by all 25 participating centres. To assure implementation of quality criteria, centres were audited to check quality indicators and document deviations. A follow-up survey was used to assess the usefulness of the project. RESULTS: Deviations were documented mainly in the areas of emergency care/patient safety (27.3% lacked regular emergency training of doctors and nurses; 22.7% inadequate emergency intervention equipment; 22.7% lacked critical incidence reporting/root cause analyses) and handling of extracts/pharmaceuticals (31.8% lacked temperature logs of fridges; 4.5% inadequate check of expiration dates). Quality improvement was initiated as shown by findings of re-audits. Usefulness of the project was rated high. CONCLUSION: The establishment of a quality management system with joint standards of care and harmonized procedures can be achieved in an international health network and ensures quality of care.