IntroductionThe commonly processed nature of the control materials used in the external quality assessment (EQA) of medical laboratories requires that their suitability is evaluated against native patient samples to ensure valid evaluation of EQA results across several measurement procedures (MPs). The aim of this study was to examine the extent to which EQA analyses of a small number of native human samples in a regular EQA survey can help to assess the suitability of routinely distributed processed EQA materials (EQAMs), demonstrated by testosterone, progesterone, and 17β-estradiol measurements in human sera.MethodsLaboratory results for the native and processed EQAMs were comparatively analyzed using a mixed-effects model. This estimated the sample type-specific mean natural logarithm (ln) bias to the reference measurement value and mean differences in ln bias between the two sample types, each with a 95%-confidence interval. Applying quite strict commutability criteria defined in consideration of clinical guidelines enabled the identification of analyte/reagent manufacturer pairings exhibiting only minor differences in bias between sample types. For pairings showing differences in bias between the two sample types that exceeded the commutability criterion, efforts were made to differentiate between material- and MP-related contributions to the model outcomes – referred to as non-commutability and trueness bias, respectively.ResultsStrongly scattered bias of the native EQAMs for some MPs revealed issues with measurement performances, such as inappropriate calibration or specificity. Consistent bias but distinct differences in bias between sample types indicated issues with commutability. The two-stage assessment revealed that the processed EQAMs were suitable for EQA purposes in most pairings. In two exceptions (testosterone/DG and progesterone/BE), the processed materials showed insufficient commutability. The limited number of EQAMs may result in inconclusive commutability assessments for individual analyte/MP pairings, four in this study, but allows for targeted follow-up with additional native EQAMs or comprehensive commutability studies.ConclusionCompared to conventional commutability studies, these proposed EQA comparability studies that use comparative native EQAMs offer EQA providers a more efficient and resource-conserving approach to assess the suitability and commutability of EQAMs by leveraging existing infrastructures. Nevertheless, even this more pragmatic approach remains resource-intensive and is inherently restricted to specific questions and selected analytes.

Management of malaria-negative febrile patients is hampered by a lack of rapid diagnostic tests (RDTs) that guide treatment decisions, increasing the risks of antibiotic overuse and antimicrobial resistance. The simultaneous detection of malaria and C-reactive protein (CRP), a potentially useful host biomarker for distinguishing between bacterial and nonbacterial infections, using RDTs could help address this challenge. A prospective study was conducted at seven sites in India from April to December 2019 to evaluate the performance of the SD BIOSENSOR STANDARD™ Q Malaria/CRP Duo Test (SD BIOSENSOR, Gyeonggi-do, South Korea) against expert microscopy for malaria and against a commercial biochemistry kit for CRP, with a total of 1,799 patients with suspected malaria included in the analysis. The prevalence of malaria parasitemia according to microscopy was 13.3% (3.3% Plasmodium falciparum [P. falciparum], 10.1% Plasmodium vivax [P. vivax]). The Duo test was used to diagnose malaria, P. falciparum, and P. vivax infections, with sensitivities of 97.9% (95% CI: 95.2%-99.1%), 91.4% (95% CI: 81.4%-96.3%), and 95.0% (95% CI: 90.7%-97.3%), respectively. The Duo test performed better for detecting pan malaria and P. vivax infections compared with the routine RDT (SD BIOLINE Malaria P.f/pan antigen test; sensitivity 86.1% [95% CI: 81.1%-89.9%] and 79.9% [95% CI: 73.4%-85.1%] for malaria and P. vivax, respectively). The Duo test's sensitivity and specificity for detecting CRP at levels of 20 mg/L or higher were estimated at 87.4% (95% CI: 84.7%-89.7%) and 94.0% (95% CI: 92.4%-95.3%), respectively. The satisfactory agreement between test results and standard reference methods suggests that the test can be used in malaria-endemic settings; however, additional studies are needed to assess its impact on malaria testing and antibiotic prescription practices.

Fractional exhaled nitric oxide (FeNO) is an important biomarker of asthma. Daily FeNO monitoring can provide longitudinal data better reflecting the variable nature of asthmatic inflammation versus single-point data. We studied adherence to daily home-based FeNO monitoring, and user experience with the Vivatmo me device and app in asthma patients in a multicentre, 12-week observational study. Adherence to daily FeNO was measured by percentage days covered (PDC) and proportion of adherent patients over time. Patients’ and physicians’ expectations were recorded by questionnaires at study entry, item-specific and global expectation fulfillment and net promoter categories scores at study end. Device usability was measured by User Experience Questionnaire (UEQ+) scores. FeNO values did not trigger direct management decisions. We enrolled n=85 asthma patients (n=23 GINA Step 1; n=37 Step 2-3; n=25 Step 4-5). Adherence to daily FeNO was high with a median PDC of 93.4

Fractional exhaled nitric oxide (FeNO) is an important type 2 (T2) asthma biomarker. Home-based FeNO monitoring can provide longitudinal data better reflecting the variable nature of T2 inflammation versus single-point data. We sought to compare longitudinal mean FeNO and variability (CV) in relation to asthma control, and to compare detection rate of T2FeNO inflammation at diagnostic (≥ 40 ppb in GINA 1) and on-treatment (≥ 25 ppb in GINA 2–5) cutoffs during home versus clinic measurements. This was an observational study with once-daily home-based FeNO (Vivatmo me) and symptom diary in patients with asthma of different GINA steps performed over 3 months. Clinic FeNO, forced expiratory volume in 1 s (FEV1), and 5-item asthma control questionnaire (ACQ-5) scores were also collected at two visits (enrolment/study end). We enrolled 85 patients (n = 23 step 1, n = 37 steps 2–3, and n = 25 steps 4–5). Mean FeNO over 3 months was highest in uncontrolled steps 4–5 (p = 0.006), and FeNO variability in steps 2–3 (p = 0.046). Subjects with optimal control (ACQ < 0.75 both visits) had comparable mean FeNO values, but fewer patients with CV above the median vs. suboptimally controlled patients (39.1

To assess the impact of an intervention package on the prescription of antibiotic and subsequently the rate of clinical recovery for non-severe acute febrile illnesses at primary health centers. Patients over 6 months of age presenting to primary health care centres with fever or history of fever within the past 7 days were randomized to receive either the intervention package constituted of point-of-care tests including COVID-19 antigen tests, a diagnostic algorithm and training and communication packages, or the standard practice. The primary outcomes were antibiotic prescriptions at Day 0 (D0) and the clinical recovery at Day 7 (D7). Secondary outcomes were non-adherence of participants and parents/caregivers to prescriptions, health workers’ non-adherence to the algorithm, and the safety of the intervention. A total of 1098 patients were enrolled. 551 (50.2

AIMS:We aim to assess the theoretical impact of the atrial flow regulator (AFR) on survival in heart failure. METHODS AND RESULTS:The prospective, multicentre, open-label, non-randomised PRELIEVE study (NCT03030274) assessed the safety and efficacy of the Occlutech AFR device in patients with symptomatic heart failure with reduced ejection fraction (HFrEF) (left ventricular ejection fraction (LVEF) ≥ 15% and <40%) or heart failure with preserved ejection fraction (HFpEF) (LVEF ≥40% and <70%) and elevated PCWP (≥15 mmHg at rest or ≥25 mmHg during exercise). In this analysis, after the first 60 patients completed 12 months of follow-up, the theoretical impact of AFR implantation on survival was assessed by comparing the observed mortality rate with the median predicted probability for one-year mortality. Each subject's risk of mortality was predicted from individual baseline data using the Meta-Analysis Global Group in Chronic HF (MAGGIC) prognostic model. A total of 87 patients (46% female, median age 69 years [IQR 62-74]) had undergone successful device implantation for the treatment of HFrEF (53%) and HFpEF (47%). Sixty patients had a complete 12 month follow-up. The median follow-up was 351 days (interquartile range [IQR] 202-370). Six (7%) patients died during follow-up (8.6 deaths per 100 patient-years; 95% confidence interval [CI] 2.7 to 15.5), all of which had HFrEF. The median predicted mortality rate for the overall study population was 12.2 deaths per 100 patient-years (95% CI 10.2 to 14.7). While the observed mortality rate (0 deaths per 100 patient-years) was significantly lower than the median predicted mortality rate (9.3 deaths per 100 patient-years; 95% CI 8.4 to 11.1) in patients with HFpEF (-9.3 deaths per 100 patient-years; 95% CI -11.1 to -8.4), there was no difference in patients with HFrEF (-3.6 deaths per 100 patient-years; 95% CI -9.5 to 3.0). Four deaths were HF-related deaths (5.7 HF-related deaths per 100 patient-years; 95% CI 1.4 to 11.9; 10.8 HF-related deaths per 100 patient-years; 95% CI 2.5 to 23.1 in the HFrEF subgroup). CONCLUSIONS:In patients with HFpEF, the mortality rate following AFR implantation was lower than the predicted mortality rate. Dedicated randomised, controlled trials are needed - and currently ongoing - to investigate whether the AFR improves mortality.

Accurate and precise point-of-care (POC) testing for C-reactive protein (CRP) can help support healthcare providers in the clinical management of patients. Here, we compared the analytical performance of 17 commercially available POC CRP tests to enable more decentralized use of the tool. The following CRP tests were evaluated. Eight quantitative tests: QuikRead go (Aidian), INCLIX (Sugentech), Spinit (Biosurfit), LS4000 (Lansionbio), GS 1200 (Gensure Biotech), Standard F200 (SD Biosensor), Epithod 616 (DxGen), IFP-3000 (Xincheng Biological); and nine semi-quantitative tests: Actim CRP (ACTIM), NADAL Dipstick (nal von minden), NADAL cassette (nal von minden), ALLTEST Dipstick (Hangzhou Alltest Biotech), ALLTEST Cassette cut-off 10-40-80 (Hangzhou Alltest Biotech), ALLTEST Cassette cut-off 10-30 (Hangzhou Alltest Biotech), Biotest (Hangzhou Biotest Biotech), BTNX Quad Line (BTNX), BTNX Tri Line (BTNX). Stored samples (n = 660) had previously been tested for CRP using Cobas 8000 Modular analyzer (Roche Diagnostics International AG, Rotkreuz, Switzerland (reference standards). CRP values represented the clinically relevant range (10-100 mg/L) and were grouped into four categories (<10 mg/L, 10-40 mg/L or 10-30 mg/L, 40-80 mg/L or 30-80 mg/L, and > 80mg/L) for majority of the semi-quantitative tests. Among the eight quantitative POC tests evaluated, QuikRead go and Spinit exhibited better agreement with the reference method, showing slopes of 0.963 and 0.921, respectively. Semi-quantitative tests with the four categories showed a poor percentage agreement for the intermediate categories and higher percentage agreement for the lower and upper limit categories. Analytical performance varied considerably for the semi-quantitative tests, especially among the different categories of CRP values. Our findings suggest that quantitative tests might represent the best choice for a variety of use cases, as they can be used across a broad range of CRP categories.

Abstract Objective Intraoperative arterial hypotension (IOH) is associated with poor patient outcome. This study aims to compare the hemodynamic effects of Cafedrine/Theodrenaline (C/T) and Noradrenaline (NA) for the treatment of hypotension in patients who develop IOH after anesthesia induction. Research design and methods This is a national, randomized, parallel-group, multicenter, and open-label study. Adult patients (≥50 years, ASA-classification III–IV) who undergo elective surgery will be included. When IOH (MAP <70 mmHg) develops, C/T or NA will be given as a bolus injection (“bolus phase”, 0–20 min after initial application) and subsequently as continuous infusion (“infusion phase”, 21–40 min after initial application) to achieve MAP = 90 mmHg. Hemodynamic data are captured in real time by advanced hemodynamic monitoring. Results Primary endpoints, i.e. the treatment-related difference in average mean arterial pressure (MAP) during the “infusion phase” and the treatment-related difference in average cardiac index during the “bolus phase” are assessed (fixed-sequence method). Non-inferiority of C/T compared to NA in achieving 90 mmHg (MAP) when applied as continuous infusion is hypothesized. In addition, superiority of C/T over NA, applied as bolus injection, in increasing cardiac index is postulated. It is estimated that 172 patients are required to establish statistical significance with a power of 90%. After adjusting for ineligibility and dropout rate, 220 patients will be screened. Conclusion This clinical trial will yield evidence for marketing authorization of C/T applied as continuous infusion. Additionally, the effects of C/T compared to NA on cardiac index will be assessed. First results of the “HERO”-study are expected in 2024. DRKS identifier: DRKS00028589. EudraCT identifier: 2021-001954-76.

Summary Background Antigen-detecting rapid diagnostic tests (Ag-RDTs) for SARS-CoV-2 are important diagnostic tools. We assessed clinical performance and ease-of-use of seven Ag-RDTs in a prospective, manufacturer-independent, multi-centre cross-sectional diagnostic accuracy study to inform global decision makers. Methods Unvaccinated participants suspected of a first SARS-CoV-2 infection were recruited at six sites (Germany, Brazil). Ag-RDTs were evaluated sequentially, with collection of paired swabs for routine reverse transcription polymerase chain reaction (RT-PCR) testing and Ag-RDT testing. Performance was compared to RT-PCR overall and in sub-group analyses (viral load, symptoms, symptoms duration). To understandusability a System Usability Scale (SUS) questionnaire and ease-of-use (EoU) assessment were performed. Findings 7471 participants were included in the analysis. Sensitivities across Ag-RDTs ranged from 70·4%-90·1%, specificities were above 97·2% for all Ag-RDTs but one (93·1%).Ag-RDTs, Mologic, Bionote, Standard Q, showed diagnostic accuracy in line with WHO targets (> 80% sensitivity, > 97% specificity). All tests showed high sensitivity in the first three days after symptom onset (≥87·1%) and in individuals with viral loads≥ 6 log10SARS-CoV2 RNA copies/mL (≥ 88·7%). Usability varied, with Rapigen, Bionote and Standard Q reaching very good scores; 90, 88 and 84/100, respectively. Interpretation Variability in test performance is partially explained by variable viral loads in population evaluated over the course of the pandemic. All Ag-RDTs reach high sensitivity early in the disease and in individuals with high viral loads, supporting their role in identifying transmission relevant infections. For easy-to-use tests, performance shown will likely be maintained in routine implementation. Funding Ministry of Science, Research and Arts, State of Baden-Wuerttemberg, Germany, internal funds from Heidelberg University Hospital, University Hospital Charité − Universitätsmedizin Berlin, UK Department of International Development, WHO, Unitaid.

Background Sympathomimetic drugs are a therapeutic cornerstone for the management of hypotensive states like intraoperative hypotension (IOH). While cafedrine/theodrenaline (C/T) is widely used in Germany to restore blood pressure in patients with IOH, more research is required to compare its effectiveness with alternatives such as ephedrine (E) that are more commonly available internationally. Methods HYPOTENS (NCT02893241, DRKS00010740) was a prospective, national, multicenter, open-label, two-armed, non-interventional study that compared C/T with E for treatment of IOH. We describe a prospectively defined cohort of patients >= 50 years old with comorbidities undergoing general anesthesia induced with propofol and fentanyl. Primary objectives were to examine treatment precision, rapidity of onset and the ability to restore blood pressure without relevant increases in heart rate. Secondary endpoints were treatment satisfaction and the number of required additional boluses or other accompanying measures. Results A total of 1496 patients were included in the per protocol analysis. Overall, effective stabilization of blood pressure was achieved with both C/T and E. Post-hoc analysis showed that blood pressure increase from baseline was more pronounced with C/T. Fewer additional boluses or other accompanying measures were required in the C/T arm. The incidence of tachycardia was comparable between groups. Post-hoc analysis showed that E produced dose-dependent elevated heart rate values. By contrast, heart rate remained stable in patients treated with C/T. Physicians reported a higher level of treatment satisfaction with C/T, with a higher proportion of anesthetists rating treatment precision and rapidity of onset as good or very good when compared with E. Conclusion Neither drug was superior in restoring blood pressure levels; however, post-hoc analyses suggested that treatment is more goal-orientated and easier to control with C/T. Heart rate was shown to be more stable with C/T and fewer additional interventions were required to restore blood pressure, which could have contributed to the increased treatment satisfaction reported by anesthetists using C/T.

The Prostate Specific Antigen (PSA) test suffers from low specificity for the diagnosis of Prostate Cancer (PCa). We originally discovered two cancer-related proteins thrombospondin-1 (THBS1) and cathepsin D (CTSD) using a mass-spectrometry-based proteomics approach. The two serum proteins were shown to improve the diagnosis of high-grade PCa. Thus, we developed quantitative ELISAs for the determination of their concentration in human serum. Here we report their analytical performance in terms of limit of detection, specificity, precision, linearity and interferences, which were determined based on CLSI guidelines. Further, we investigated the influence of pre-analytical factors on concentration measurements. For this, blood from 4-6 donors was collected in different tubes and stored at room temperature for different times prior to centrifugation at different centrifugal forces and temperatures. Stability of THBS1 and CTSD under different storage temperatures was also evaluated. Our results show that the assays are specific, linear and sensitive enough to allow measurement of clinical samples. Precision in terms of repeatability and total within-laboratory coefficient of variation (CV) are 5.5% and 8.1% for THBS1 and 4.3% and 7.2% for CTSD, respectively. Relative laboratory-to-laboratory differences were -6.3% for THBS1 and -3% for CTSD. Both THBS1 and CTSD were stable in serum samples, with 80-120% recoveries of concentrations across donors, sample preparation and storage. In conclusion, the ELISAs as part of the novel commercial in vitro diagnostic test Proclarix are suitable for the use in clinical practice. THBS1 and CTSD can be accurately measured for their intended use independent of the lot and laboratory when conditions consistent with routine practice for PSA sampling and storage are used.

Objectives:Selecting patients suspected of having prostate cancer (PCa) for a prostate biopsy remains a challenge. Prostate-specific antigen (PSA)-based testing is hampered by its low specificity that often leads to negative biopsy results or detection of clinically insignificant cancers, especially in the 2-10 ng/mL range. The objective was to evaluate a novel diagnostic test called Proclarix incorporating thrombospondin-1 and cathepsin D alongside total and free PSA as well as age for predicting clinically significant PCa.Patients and methods:The test was developed following a retrospective study design using biobanked samples of 955 men from two reference centres. A multivariate approach was used for model development followed by validation to discriminate significant (grade group ≥2) from insignificant or no cancer at biopsy. The test specificity, positive predictive value (PPV) and negative predictive value (NPV) at a fixed sensitivity of 90% were compared to percent free PSA (%fPSA) alone. The number of avoidable prostate biopsies deemed to be representative of clinical utility was also assessed.Results:In the targeted patient population, the test displayed increased diagnostic accuracy compared to %fPSA alone. Application of the established model on 955 patients at a fixed sensitivity of 90% for significant disease resulted in a specificity of 43%, NPV of 95% and a PPV of 25%. This is in comparison to a specificity of 17%, NPV of 89% and PPV of 19% for %fPSA alone and had the potential to reduce the total number of biopsies needed to identify clinically significant cancer. Further, the test score correlated with significance of cancer assessed on prostate biopsy.Conclusions:The Proclarix test can be used as an aid in the decision-making process if to biopsy men in this challenging patient population. The use of the test could reduce the number of biopsies performed avoiding invasive procedures, anxiety, discomfort, pain and complications.

Background: Fractional exhaled nitric oxide (FeNO) is a surrogate marker for airway inflammation, supporting the diagnostic pathway and treatment decisions for asthma patients. Objectives: Aim of this study was to compare the new analyser Vivatmo pro (Bosch, BV) with NIOX VERO (Circassia, CN) and CLD (Ecomedics, EC). Methods: In 100 asthmatics (median 53 years [range 20-87], 62% female, 86% on inhaled corticosteroids [mean 1,300 mu g beclomethasone dipropionate or equivalent], 35% treated with biologics) 2 FeNO measurements per device were performed. Additionally, the success rate to achieve a valid NO value was evaluated. Results: Sixty-eight percent of the patients had FeNO values below 50 ppb. Median NO concentrations were 31 ppb (range 6-194) for BV, 33 ppb (9-164) for CN and 31ppb (7-353) for EC. Bland-Altman plots suggested an agreement within the predefined limits of +/- 5 ppb for all analysers within the therapeutically relevant range (0-70 ppb). The highest agreement in FeNO levels were between BV and EC with mean differences of -0.26 (95% CI -1.48 to 0.95) vs. 1.52 (95% CI 0.4-2.6) ppb for CN and EC. The results indicate an equivalence of the methods (two-one sided t test-equivalence test: p < 0.0001, +/- 5 ppb margins). Acceptance of the measurements was high for all devices (97%). The highest success rate to obtain 2 valid NO values without failed attempts was achieved with the BV analyser (73 vs. 62% for the CN analyser and 46% for the EC analyser). Conclusions: For the range between 0 and 70 ppb, FeNO concentrations measured with all 3 devices were statistically equivalent within predefined acceptance criteria and did not differ in a clinically relevant way.

Objectives: Infantile colic is a common benign disease occurring in early infancy that may have a great impact on family life. In the present study, the effectiveness and safety of the complex homeopathic medicine Enterokind was compared with Simethicone for treating infantile colic. Design and setting: Current data were drawn from a prospective, multicenter, randomized, open-label, controlled clinical trial that was conducted in 2009 in 3 Russian outpatient clinics. Children received either Enterokind (Chamomilla D6, Cina D6, Colocynthis D6, Lac defloratutn D6 and Magnesium chloratum D6) or Simethicone. Data from infants <= 6 months with infantile colic are presented here. Main outcome measures: The main outcomes assessments were the change of total complaints score (maximum 17 points) and total objective symptoms score (maximum 22 points) after 10 days of treatment. Results: Data from 125 infants <= 6 months with infantile colic were analyzed. The differences in total complaints and objective symptoms scores between baseline and day 10, estimated from the ANCOVA model, were found to be highly significant (p < 0.0001; ITT) in favor of Enterokind, both for complaints (Delta = -2.38; 95% confidence interval (CI): [-2.87; -1.89]) and for objective symptoms (Delta =-2.07; 95% CI: [-2.65; -1.49]). 1 adverse event (AE), vomiting, occurred under Enterokind and was rated to be unlikely related to it; 4 AEs occurred under Simethicone. All AEs were non-serious. Conclusions: The current study indicates that Enterokind is an effective and safe homeopathic treatment for functional intestinal colic in infants <= 6 months.

Current evidence suggests that patients with Luminal A early breast cancer can skip chemotherapy or extended endocrine therapy, but immunohistochemistry-based biomarker analysis for St Gallen subtyping may not be reproducible. We asked whether RT-qPCR can be used instead to address this clinical question. RNA was extracted from tumor material derived from ER+/HER2- patients receiving adjuvant endocrine treatment for low-risk cancers and was semi-quantified by RT-qPCR with the MammaTyper®. St Gallen subtypes were based on the mRNA expression of ERBB2/HER2, ESR1/ER, PGR/PR and MKI67/Ki67 after dichotomizing at predefined cut-offs. Differences in distant disease-free survival (DDFS) were assessed by Kaplan Meier analysis and Cox regression. With a median follow up of 7.8 years, there were ten events in the group of 195 Luminal A-like tumors (5.1%) and 18 events in the remaining 127 tumors (14.1%), consisting mostly of Luminal B-like cases (N = 119). Luminal A-like had significantly better DDFS over the entire follow-up period (HR 0.35, 95% CIs 0.16–0.76, p = 0.0078) with a trend towards reduced probability of recurrences also in the late phase (> 5 years) (HR 0.20, p = 0.052). The survival advantage spanning the entire follow-up period persisted in the pN0 or pN0-N1 subgroups or after correcting for clinicopathological parameters. MKI67 alone significantly predicted for worse DDFS (HR 2.62, 95% CIs 1.24–5.56, p = 0.0088). St Gallen Luminal A-like tumors identified by RT-qPCR display markedly low rates of distant recurrence at ten years follow-up. Patients with such tumors could be spared chemotherapy due to the obviously unfavourable benefit/toxicity ratio.

Background and Aims: The current recommendations of watchful waiting for patients affected by a moderate recurrent tonsillitis (RT) shed an interesting light on homeopathy as a treatment option. The current trial was set up to investigate the clinical effectiveness and safety of the complex homeopathic medication Tonsilotren in patients with moderate RT.

Abstract Background: Estrogen receptor (ER/ESR1), progesterone receptor (PR/PGR) and epidermal growth factor receptor 2 (HER2/ERBB2) are routinely assessed by immunohistochemistry (IHC) during workup of breast cancer samples. The routine use of Ki67 (MKI67) IHC assessment in the context of breast cancer subtyping, however, remains controversial, due to poor reproducibility and lack of standardization. The MammaTyper® test is an in-vitro diagnostic (IVD) test which measures the expression status of the four breast cancer biomarkers ERBB2, ESR1, PGR and MKI67 on the mRNA level via reverse transcription-quantitative PCR (RT-qPCR) and has demonstrated a high degree of reproducibility in the assessment of the four markers. In this retrospective analysis we assessed the prognostic power of molecular subtyping by MammaTyper® in archived samples from low risk early breast cancers treated with adjuvant endocrine therapy only. Methods: ER+/HER2- (according to initial diagnosis) FFPE breast cancer samples from patients treated with adjuvant endocrine therapy only were obtained from 6 different centers. Tumor cellularity was assessed by H&E staining and RNA was extracted from samples with a tumor cell content of ≥20% using a bead-based RNA purification kit (RNXtract®). Total RNA was then used as input for MammaTyper® RT-qPCR. Expression values were classified as positive or negative for each marker based on predefined cutoff values. Tumor subtypes were assigned to each sample based on the combination of binary (pos/neg) single marker expression status according the St Gallen surrogate subtype definition. Distant disease free survival of Luminal A-like samples vs. samples with other subtypes was assessed by Kaplan Meier analysis and Cox regression using SAS version 9.4. Results: The final analysis included 319 samples with sufficient tumor cellularity and RNA content for reliable analysis. The rate of distant recurrence in the analyzed set was 8.5%. Median follow up was 7.8 years. The MammaTyper® test called 60% (192) of samples as Luminal-A-like (4.7% (9) distant events), 37% (119) as Luminal B-like (HER2 negative) (13.4% (16) distant events), 1.3% (4) as Triple negative (ductal) (25% (1) distant events), 0.6% (2) as “not defined according to St Gallen” (ESR1-/PGR+) (50% (1) distant events) and 0.6% (2) as Luminal B-like (HER2 positive) (no distant events). When comparing Luminal A-like samples with the samples of the other subtypes in survival analysis, Luminal A-like samples had a significantly better distant disease free survival when assessing samples from patients with pN0 status (278) (p=0.0177, HR=0.344 (95% CI 0.137-0.866), pN1 status (0-3 affected nodes) (314) (p=0.0153, HR=0.374 (95% CI 0.163-0.855) as well as for all samples (p=0.0032, HR=0.319 (95% CI 0.143-0.711). Conclusion: Determination of HER2, ER, PR and Ki67 mRNA levels allows molecular subtyping according to the St Gallen surrogate subtype definition. Low risk of distant recurrence could be confirmed for the MammaTyper® Luminal A-like samples suggesting that for this patient group endocrine treatment alone may be sufficient. The high degree of standardization of mRNA measurement may drive the use of the Ki67/MKI67 biomarker in routine breast cancer pathology. Citation Format: Laible M, Hartmann K, Gürtler C, Anzeneder T, Weber S, Keller T, Sahin U. Prediction of distant recurrence in low risk early breast cancer by RT-qPCR based subtyping using MammaTyper® [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-08-14.