Follow-Up Study of Effectiveness of 23-Valent Pneumococcal Polysaccharide Vaccine Against All-Type and Serotype-Specific Invasive Pneumococcal Disease, Denmark.

As a follow-up to a previous study, we investigated vaccine effectiveness (VE) of 23-valent pneumococcal polysaccharide vaccine (PPSV23) against invasive pneumococcal disease (IPD) among 1,254,498 persons >65 years of age as part of a vaccination program in Denmark during April 2020-January 2023. We assessed VE by using a Cox regression model and adjusted for age, sex, and underlying conditions. Using nationwide data, we estimated a VE of PPSV23 against all-type IPD of 32% and against PPSV23-serotype IPD of 41%. Because this follow-up study had more statistical power than the original study, we also estimated VE against IPD caused by PPSV23-serotypes excluding serotype 3; serotype 3; serotype 8; serotype 22F; PPSV23 non-PCV15 serotypes; PPSV23 non-PCV20 serotypes; and IPD over time. Our findings suggest PPSV23 vaccination can protect persons >65 years of age against IPD caused by all serotypes or serotype groupings, except serotype 3.

Infection, recovery and re-infection of farmed mink with SARS-CoV-2.

Mink, on a farm with about 15,000 animals, became infected with SARS-CoV-2. Over 75% of tested animals were positive for SARS-CoV-2 RNA in throat swabs and 100% of tested animals were seropositive. The virus responsible had a deletion of nucleotides encoding residues H69 and V70 within the spike protein gene as well as the A22920T mutation, resulting in the Y453F substitution within this protein, seen previously in mink. The infected mink recovered and after free-testing of 300 mink (a level giving 93% confidence of detecting a 1% prevalence), the animals remained seropositive. During further follow-up studies, after a period of more than 2 months without any virus detection, over 75% of tested animals again scored positive for SARS-CoV-2 RNA. Whole genome sequencing showed that the viruses circulating during this re-infection were most closely related to those identified in the first outbreak on this farm but additional sequence changes had occurred. Animals had much higher levels of anti-SARS-CoV-2 antibodies in serum samples after the second round of infection than at free-testing or during recovery from initial infection, consistent with a boosted immune response. Thus, it was concluded that following recovery from an initial infection, seropositive mink were readily re-infected by SARS-CoV-2.

High titers of neutralizing SARS-CoV-2 antibodies six months after symptom onset are associated with increased severity in COVID-19 hospitalized patients.

BACKGROUND: Viral shedding and neutralizing antibody (NAb) dynamics among patients hospitalized with severe coronavirus disease 2019 (COVID-19) and immune correlates of protection have been key questions throughout the pandemic. We investigated the duration of reverse transcriptase-polymerase chain reaction (RT-PCR) positivity, infectious viral shedding and NAb titers as well as the association between NAb titers and disease severity in hospitalized COVID-19 patients in Denmark 2020-2021. MATERIALS AND METHODS: Prospective single-center observational cohort study of 47 hospitalized COVID-19 patients. Oropharyngeal swabs were collected at eight time points during the initial 30 days of inclusion. Serum samples were collected after a median time of 7 (IQR 5 - 10), 37 (IQR 35 - 38), 97 (IQR 95 - 100), and 187 (IQR 185 - 190) days after symptom onset. NAb titers were determined by an in-house live virus microneutralization assay. Viral culturing was performed in Vero E6 cells. RESULTS: Patients with high disease severity had higher mean log2 NAb titers at day 37 (1.58, 95% CI [0.34 -2.81]), 97 (2.07, 95% CI [0.53-3.62]) and 187 (2.49, 95% CI [0.20- 4.78]) after symptom onset, compared to patients with low disease severity. Peak viral load (0.072, 95% CI [- 0.627 - 0.728]), expressed as log10 SARS-CoV-2 copies/ml, was not associated with disease severity. Virus cultivation attempts were unsuccessful in almost all (60/61) oropharyngeal samples collected shortly after hospital admission. CONCLUSIONS: We document an association between high disease severity and high mean NAb titers at days 37, 97 and 187 after symptom onset. However, peak viral load during admission was not associated with disease severity. TRIAL REGISTRATION: The study is registered at https://clinicaltrials.gov/ (NCT05274373).

SARS-CoV-2 Antibody Responses Are Correlated to Disease Severity in COVID-19 Convalescent Individuals.

Globally, the COVID-19 pandemic has had extreme consequences for the healthcare system and has led to calls for diagnostic tools to monitor and understand the transmission, pathogenesis, and epidemiology, as well as to evaluate future vaccination strategies. In this study, we have developed novel, to our knowledge, flexible ELISA-based assays for specific detection of human SARS-CoV-2 Abs against the receptor-binding domain, including an Ag sandwich ELISA relevant for large population screening and three isotype-specific assays for in-depth diagnostics. Their performance was evaluated in a cohort of 350 convalescent participants with previous COVID-19 infection, ranging from asymptomatic to critical cases. We mapped the Ab responses to different areas on protein N and S and showed that the IgM, A, and G Ab responses against receptor-binding domain are significantly correlated to the disease severity. These assays and the data generated from them are highly relevant for diagnostics and prognostics and contribute to the understanding of long-term COVID-19 immunity.

Estimation of SARS-CoV-2 Infection Fatality Rate by Age and Comorbidity Status Using Antibody Screening of Blood Donors During the COVID-19 Epidemic in Denmark.

BACKGROUND: Studies presenting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection fatality rate (IFR) for healthy individuals are warranted. We estimate IFR by age and comorbidity status using data from a large serosurvey among Danish blood donors and nationwide data on coronavirus disease 2019 (COVID-19) mortality. METHODS: Danish blood donors aged 17-69 years donating blood October 2020-February 2021 were tested with a commercial SARS-CoV-2 total antibody assay. IFR was estimated for weeks 11 to 42, 2020 and week 43, 2020 to week 6, 2021, representing the first 2 waves of COVID-19 epidemic in Denmark. RESULTS: In total, 84944 blood donors were tested for antibodies. The seroprevalence was 2% in October 2020 and 7% in February 2021. Among 3898039 Danish residents aged 17-69 years, 249 deaths were recorded. The IFR was low for people <51 years without comorbidity during the 2 waves (combined IFR=3.36 per 100000 infections). The IFR was below 3‰ for people aged 61-69 years without comorbidity. IFR increased with age and comorbidity but declined from the first to second wave. CONCLUSIONS: In this nationwide study, the IFR was very low among people <51 years without comorbidity.

Effect of Influenza Vaccination on Risk of Coronavirus Disease 2019: A Prospective Cohort Study of 46†000 Healthcare Workers.

BACKGROUND: The purpose of this study was to assess whether influenza vaccination has an impact on the risk of coronavirus disease 2019 (COVID-19). METHODS: A cohort of 46 112 healthcare workers were tested for antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and filled in a survey on COVID-19 symptoms, hospitalization, and influenza vaccination. RESULTS: The risk ratio of hospitalization due to SARS-CoV-2 for influenza vaccinated compared with unvaccinated participants was 1.00 for the seasonal vaccination in 2019/2020 (confidence interval, .56-1.78, P = 1.00). Likewise, no clinical effect of influenza vaccination on development of antibodies against SARS-CoV-2 was found. CONCLUSIONS: The present findings indicate that influenza vaccination does not affect the risk of SARS-CoV-2 infection or COVID-19.

A low level of naturally occurring antibodies associates with functional antibody deficiency.

Functional antibody deficiency is clinically assessed from antibody responses to vaccination. However, diagnostic vaccination is complex and may fail in practice. We hypothesized that the levels of naturally occurring antibodies against galactose-α-1,3-galactose (αGal) may represent alternative markers of functional antibody capacity. We included data from 229 patients with suspected primary immunodeficiency in a retrospective study. Antibody levels against αGal and twelve pneumococcal serotypes were determined with solid-phase immunoassays. Pneumococcal vaccinations and treatment with normal human immunoglobulin were assessed from medical records. Anti-αGal antibody levels correlated positively with anti-pneumococcal antibody levels measured before and after pneumococcal vaccination. Contrary to the anti-pneumococcal antibody levels, the anti-αGal antibody level showed potential for predicting subsequent immunoglobulin treatment - a marker of disease severity. Naturally occurring antibodies may reflect the functional capacity tested by diagnostic vaccination but add more useful clinical data. The clinical utility of this easy test should be evaluated in prospective studies.

Response to pneumococcal conjugate and polysaccharide vaccination in children with rheumatic disease.

Children with rheumatic disease and compromised immune system have an increased risk of infection. Streptococcus pneumoniae is a frequent pathogen, and immunization is recommended. In this study, we investigated whether immunocompromised children with rheumatic disease do respond to pneumococcal immunization with 13-valent pneumococcal conjugate vaccine followed by 23-valent pneumococcal polysaccharide vaccine. The study was conducted at two tertiary referral hospitals in Denmark from 2015 to 2018. Patients with rheumatic disease and compromised immune system aged 2-19 years were eligible. Patients were vaccinated with 13-valent pneumococcal conjugate vaccine followed by 23-valent pneumococcal polysaccharide vaccine. A blood sample was collected before vaccination and after each vaccination. IgG antibodies were quantified for twelve serotypes. Seroprotection for each serotype was defined as IgG ≥0.35 µg/mL. A total of 27 patients were enrolled. After the conjugate vaccine, an increase in antibody titres compared with pre-vaccination was found for all serotypes and 9/12 were significant. After the polysaccharide vaccine, the antibody titres for all serotypes but one was seen to increase but none reached significance. The proportion of patients protected before immunization ranged from 20.8% to 100% for the individual serotypes. Odds ratio for achieving seroprotection after the conjugate vaccine was >1 for 10/12 serotypes but only significant for three serotypes. After the polysaccharide vaccine, the odds ratio was >1 for 9/12 serotypes but none reached significance. In conclusion, children with rheumatic disease and compromised immune system respond to pneumococcal immunization with 13-valent pneumococcal conjugate vaccine and maintain antibody levels upon subsequent immunization with 23-valent pneumococcal polysaccharide vaccine.

Effectiveness of the 23-valent pneumococcal polysaccharide vaccine against invasive pneumococcal disease among 948,263 individuals ≥ 65 years of age: a Danish cohort study.

This study aimed to estimate the effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPV23) against invasive pneumococcal disease (IPD) among individuals ≥ 65 years of age. We used Danish nationwide databases to obtain information on PPV23 vaccination, covariates, and IPD and linked data on an individual level using a unique personal identifier. A total of 948,263 individuals were included and followed between June 15, 2020, and September 18, 2021 (58.6% were vaccinated during follow-up). The adjusted vaccine effectiveness was 42% (95% confidence interval (CI): 9-63%) for all-serotype IPD and 58% (95% CI: 21-78%) for PPV23-serotype IPD, using no vaccination as the reference.

Seroprevalence of SARS-CoV-2 antibodies in social housing areas in Denmark.

BACKGROUND: COVID-19 is thought to be more prevalent among ethnic minorities and individuals with low socioeconomic status. We aimed to investigate the prevalence of SARS-CoV-2 antibodies during the COVID-19 pandemic among citizens 15 years or older in Denmark living in social housing (SH) areas. METHODS: We conducted a study between January 8th and January 31st, 2021 with recruitment in 13 selected SH areas. Participants were offered a point-of-care rapid SARS-CoV-2 IgM and IgG antibody test and a questionnaire concerning risk factors associated with COVID-19. As a proxy for the general Danish population we accessed data on seroprevalence from Danish blood donors (total Ig ELISA assay) in same time period. RESULTS: Of the 13,279 included participants, 2296 (17.3%) were seropositive (mean age 46.6 (SD 16.4) years, 54.2% female), which was 3 times higher than in the general Danish population (mean age 41.7 (SD 14.1) years, 48.5% female) in the same period (5.8%, risk ratios (RR) 2.96, 95% CI 2.78-3.16, p > 0.001). Seropositivity was higher among males (RR 1.1, 95% CI 1.05-1.22%, p = 0.001) and increased with age, with an OR seropositivity of 1.03 for each 10-year increase in age (95% CI 1.00-1.06, p = 0.031). Close contact with COVID-19-infected individuals was associated with a higher risk of infection, especially among household members (OR 5.0, 95% CI 4.1-6.2 p < 0,001). Living at least four people in a household significantly increased the OR of seropositivity (OR 1.3, 95% CI 1.0-1.6, p = 0.02) as did living in a multi-generational household (OR 1.3 per generation, 95% CI 1.1-1.6, p = 0.003). Only 1.6% of participants reported not following any of the national COVID-19 recommendations. CONCLUSIONS: Danish citizens living in SH areas of low socioeconomic status had a three times higher SARS-CoV-2 seroprevalence compared to the general Danish population. The seroprevalence was significantly higher in males and increased slightly with age. Living in multiple generations households or in households of more than four persons was a strong risk factor for being seropositive. Results of this study can be used for future consideration of the need for preventive measures in the populations living in SH areas.

SARS-CoV-2 antibody prevalence among homeless people and shelter workers in Denmark: a nationwide cross-sectional study.

BACKGROUND: People experiencing homelessness (PEH) and associated shelter workers may be at higher risk of infection with "Severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2). The aim of this study was to determine the prevalence of SARS-CoV-2 among PEH and shelter workers in Denmark. DESIGN AND METHODS: In November 2020, we conducted a nationwide cross-sectional seroprevalence study among PEH and shelter workers at 21 recruitment sites in Denmark. The assessment included a point-of-care test for antibodies against SARS-CoV-2, followed by a questionnaire. The seroprevalence was compared to that of geographically matched blood donors considered as a proxy for the background population, tested using a total Ig ELISA assay. RESULTS: We included 827 participants in the study, of whom 819 provided their SARS-CoV-2 antibody results. Of those, 628 were PEH (median age 50.8 (IQR 40.9-59.1) years, 35.5% female) and 191 were shelter workers (median age 46.6 (IQR 36.1-55.0) years and 74.5% female). The overall seroprevalence was 6.7% and was similar among PEH and shelter workers (6.8% vs 6.3%, p = 0.87); and 12.2% among all participants who engaged in sex work. The overall participant seroprevalence was significantly higher than that of the background population (2.9%, p < 0.001). When combining all participants who reported sex work or were recruited at designated safe havens, we found a significantly increased risk of seropositivity compared to other participants (OR 2.23, 95%CI 1.06-4.43, p = 0.02). Seropositive and seronegative participants reported a similar presence of at least one SARS-CoV-2 associated symptom (49% and 54%, respectively). INTERPRETATIONS: The prevalence of SARS-CoV-2 antibodies was more than twice as high among PEH and associated shelter workers, compared to the background population. These results could be taken into consideration when deciding in which phase PEH are eligible for a vaccine, as part of the Danish national SARS-CoV-2 vaccination program rollout. FUNDING: TrygFonden and HelseFonden.

SARS-CoV-2 Transmission between Mink (Neovison vison) and Humans, Denmark.

Severe acute respiratory syndrome coronavirus 2 has caused a pandemic in humans. Farmed mink (Neovison vison) are also susceptible. In Denmark, this virus has spread rapidly among farmed mink, resulting in some respiratory disease. Full-length virus genome sequencing revealed novel virus variants in mink. These variants subsequently appeared within the local human community.

Comparison of 16 Serological SARS-CoV-2 Immunoassays in 16 Clinical Laboratories.

Serological assays for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are needed to support clinical diagnosis and epidemiological investigations. Recently, assays for large-scale detection of total antibodies (Ab), immunoglobulin G (IgG), and IgM against SARS-CoV-2 antigens have been developed, but there are limited data on the diagnostic accuracy of these assays. This study was a Danish national collaboration and evaluated 15 commercial and one in-house anti-SARS-CoV-2 assays in 16 laboratories. Sensitivity was evaluated using 150 samples from individuals with asymptomatic, mild, or moderate COVID-19, nonhospitalized or hospitalized, confirmed by nucleic acid amplification tests (NAAT); samples were collected 13 to 73 days either from symptom onset or from positive NAAT (patients without symptoms). Specificity and cross-reactivity were evaluated in samples collected prior to the SARS-CoV-2 epidemic from >586 blood donors and patients with autoimmune diseases, cytomegalovirus or Epstein-Barr virus infections, and acute viral infections. A specificity of ≥99% was achieved by all total-Ab and IgG assays except one, DiaSorin Liaison XL IgG (97.2%). Sensitivities in descending order were Wantai ELISA total Ab (96.7%), CUH-NOVO in-house ELISA total Ab (96.0%), Ortho Vitros total Ab (95.3%), YHLO iFlash IgG (94.0%), Ortho Vitros IgG (93.3%), Siemens Atellica total Ab (93.2%), Roche Elecsys total Ab (92.7%), Abbott Architect IgG (90.0%), Abbott Alinity IgG (median 88.0%), DiaSorin Liaison XL IgG (median 84.6%), Siemens Vista total Ab (81.0%), Euroimmun/ELISA IgG (78.0%), and Snibe Maglumi IgG (median 78.0%). However, confidence intervals overlapped for several assays. The IgM results were variable, with the Wantai IgM ELISA showing the highest sensitivity (82.7%) and specificity (99%). The rate of seropositivity increased with time from symptom onset and symptom severity.

Molecular characterization and epidemiology of Streptococcus pneumoniae serotype 8 in Denmark.

BACKGROUND: Streptococcus pneumoniae serotype 8 incidence has increased in Denmark after the introduction of pneumococcal conjugated vaccines (PCV). The mechanism behind the serotype 8 replacement is not well understood. In this study, we aimed to present epidemiological data on invasive pneumococcal disease (IPD) and molecular characterization of 96 serotype 8 clinical isolates. METHODS: IPD data from 1999 to 2019 were used to calculate the incidence and age distribution. Whole-genome sequencing (WGS) analysis was performed on 96 isolates (6.8% of the total serotype 8 IPD isolates in the period) to characterize the isolates with respect to pneumococcal lineage traits, a range of genes with potential species discrimination, presence of colonization and virulence factors, and molecular resistance pattern. RESULTS: The serotype 8 IPD incidence increased significantly (P < 0.05) for the age groups above 15 years after the introduction of PCV13, primarily affecting the elderly (65+). All isolates were phenotypically susceptible to penicillin, erythromycin and clindamycin. Molecular characterization revealed seven different MLST profiles with ST53 as the most prevalent lineage (87.5%) among the analyzed serotype 8 isolates. The genes covering the cell-surface proteins: lytA, rspB, pspA, psaA & Xisco and the pneumococcal toxin pneumolysin = ply were present in all isolates, while genes for the membrane transporter proteins: piaA/piaB/piaC; the capsular genes: cpsA (wzg) & psrP; the metallo-binding proteins zmpB & zmpC; and the neuroamidase proteins: nanA/nanB were variably present. Surprisingly, the putative transcriptional regulator gene SP2020 was not present in all isolates (98%). Susceptibility to penicillin, erythromycin and clindamycin was molecularly confirmed. CONCLUSION: The observed serotype 8 replacement was not significantly reflected with a change in the MLST profile or changes in antibiotic resistance- or virulence determinants.

Prevalence of SARS-CoV-2 antibodies in Denmark: nationwide, population-based seroepidemiological study.

Seroprevalence studies have proven an important tool to monitor the progression of the coronavirus disease 2019 (COVID-19) pandemic. We present results of consecutive population-based seroprevalence surveys performed in Denmark in 2020. In spring, late summer and autumn/winter of 2020, invitation letters including a questionnaire covering symptoms were sent to representative samples of the population above 12 years and to parents of children below 18 years in the sample. Blood samples were analysed for total Ig and seroprevalence estimates per population segment were calculated and compared to other surveillance parameters. Based on 34 081 participants (participation rate 33%), seroprevalence estimates increased from 1.2% (95%CI: 0.3-1.9%) in May to 4.1% (95%CI: 3.1-4.9%) in December 2020. Seroprevalence estimates were roughly three times higher in those aged 12-29 years compared to 65 + and higher in metropolitan municipalities. By December 2020, 1.5% of the population had tested positive by RT-PCR. Infected individuals in older age groups were hospitalised several fold more often than in younger. Amongst seropositives, loss of taste/smell were the more specific symptoms, 32-56% did not report any symptoms. In more than half of seroconverted families, we did not see evidence of transmission between generations. Seroprevalence increased during 2020; adolescents were primarily infected in the autumn/winter. Denmark has a high per capita test rate; roughly one undiagnosed infection of SARS-CoV-2 were estimated to occur for each diagnosed case. Approximately half were asymptomatically infected. The epidemic appears to have progressed relatively modestly during 2020 in Denmark.

Defining Polysaccharide Antibody Deficiency: Measurement of Anti-Pneumococcal Antibodies and Anti-Salmonella typhi Antibodies in a Cohort of Patients with Recurrent Infections.

BACKGROUND: The correlation between different methods for the detection of pneumococcal polysaccharide vaccine (PPV) responses to diagnose specific polysaccharide antibody deficiency (SAD) is poor and the criteria for defining a normal response lack consensus. We previously proposed fifth percentile (p5) values of PPV responses as a new cutoff for SAD. OBJECTIVE: To analyze the association of SAD (determined by either World Health Organization (WHO)-standardized ELISA or multiplex bead-based assay) with abnormal response to Salmonella (S.) typhi Vi vaccination in a cohort of patients with recurrent infections. METHODS: Ninety-four patients with a clinical history suggestive of antibody deficiency received PPV and S. typhi Vi vaccines. Polysaccharide responses to either 3 or 18 pneumococcal serotypes were measured by either the WHO ELISA or a multiplex in-house bead-based assay. Anti-S. typhi Vi IgG were measured by a commercial ELISA kit. Allohemagglutinins (AHA) were measured by agglutination method. RESULTS: Based on the American Academy of Allergy, Asthma and Immunology (AAAAI) criteria for WHO ELISA, 18/94 patients were diagnosed with SAD and 22/93 based on serotype-specific p5 cutoffs for bead-based assay. The association between the two methods was significant, with 10 subjects showing abnormal response according to both techniques. Abnormal response to S. typhi Vi vaccination was found in 7 patients, 6 of which had SAD. No correlation was found between polysaccharide response and AHA, age, or clinical phenotype. CONCLUSION: The lack of evidence-based gold standards for the diagnosis of SAD represents a challenge in clinical practice. In our cohort, we confirmed the insufficient correlation between different methods of specific PPV response measurement, and showed that the S. typhi Vi response was not contributive. Caution in the interpretation of results is warranted until more reliable diagnostic methods can be validated.

Expression of epithelial-mesenchymal transition-related markers and phenotypes during breast cancer progression.

PURPOSE: The study aimed to investigate expression of epithelial-to-mesenchymal transition (EMT)-related proteins and phenotypes during breast cancer progression and to relate this to patient outcome. METHODS: Protein expression patterns of E-cadherin, N-cadherin, twist, and vimentin were examined by immunohistochemistry on formalin-fixed paraffin-embedded samples from primary tumors (PTs) (n = 419), synchronous lymph node metastases (LNMs) (n = 131) and recurrences (n = 34) from patients included in an observational prospective primary breast cancer study. Markers were evaluated individually and combined as defined EMT phenotypes (epithelial, mesenchymal, partial EMT, and negative). EMT profiles were compared between matched tumor progression stages, and related to clinicopathological data and distant recurrence-free interval (DRFi). RESULTS: N-cadherin-positivity, vimentin-positivity, mesenchymal and partial EMT phenotypes were associated with more aggressive tumor characteristics such as triple-negative subtype. Single EMT markers and phenotype discordance rates between paired tumor samples were observed in the range of 2-35%. Non-epithelial phenotypes were more frequently identified in recurrences compared to PTs, however, no skewness of expression or phenotype was detected between PTs and matched LNMs or between PTs and matched recurrences (Exact McNemar test). Interestingly, patients with a twist positive PT had shorter DRFi, compared to patients with a twist negative PT (hazard ratio (HR) 2.4, 95% confidence interval (CI) 1.2-5.1, P = 0.02). Essentially, the same effect was seen in multivariable analysis (HR 2.5, 95% CI 0.97-6.6, P = 0.06). CONCLUSION: The epithelial phenotype was indicated to be lost between PTs and recurrences as a reflection of tumor progression. Twist status of the PT was related to long-term prognosis warranting further investigation in larger cohorts.

Evolution of Estrogen Receptor Status from Primary Tumors to Metastasis and Serially Collected Circulating Tumor Cells.

BACKGROUND: The estrogen receptor (ER) can change expression between primary tumor (PT) and distant metastasis (DM) in breast cancer. A tissue biopsy reflects a momentary state at one location, whereas circulating tumor cells (CTCs) reflect real-time tumor progression. We evaluated ER-status during tumor progression from PT to DM and CTCs, and related the ER-status of CTCs to prognosis. METHODS: In a study of metastatic breast cancer, blood was collected at different timepoints. After CellSearch® enrichment, CTCs were captured on DropMount slides and evaluated for ER expression at baseline (BL) and after 1 and 3 months of therapy. Comparison of the ER-status of PT, DM, and CTCs at different timepoints was performed using the McNemar test. The primary endpoint was progression-free survival (PFS). RESULTS: Evidence of a shift from ER positivity to negativity between PT and DM was demonstrated (p = 0.019). We found strong evidence of similar shifts from PT to CTCs at different timepoints (p < 0.0001). ER-positive CTCs at 1 and 3 months were related to better prognosis. CONCLUSIONS: A shift in ER-status from PT to DM/CTCs was demonstrated. ER-positive CTCs during systemic therapy might reflect the retention of a favorable phenotype that still responds to therapy.

Basal biomarkers nestin and INPP4B predict gemcitabine benefit in metastatic breast cancer: Samples from the phase III SBG0102 clinical trial.

In a formal prospective-retrospective analysis of the phase III SBG0102 clinical trial randomizing metastatic breast cancer patients to gemcitabine-docetaxel or to single agent docetaxel, patients with basal-like tumors by PAM50 gene expression had significantly better overall survival in the gemcitabine arm. By immunohistochemistry (IHC), triple negative status was not predictive, but more specific biomarkers have since become available defining basal-like by nestin positivity or loss of inositol-polyphosphate-4-phosphate (INPP4B). Here, we evaluate their capacity to identify which patients benefit from gemcitabine in the metastatic setting. Nestin and INPP4B staining and interpretation followed published methods. A prespecified statistical plan evaluated the primary hypothesis that patients with basal-like breast cancer, defined as "nestin+ or INPP4B-", would have superior overall survival on gemcitabine-docetaxel when compared to docetaxel. Interaction tests, Kaplan-Meier curves and forest plots were used to assess prognostic and predictive capacities of biomarkers relative to treatment. Among 239 cases evaluable for our study, 36 (15%) had been classified as basal-like by PAM50. "Nestin+ or INPP4B-" was observed in 41 (17%) of the total cases and was significantly associated with PAM50 basal-like subtype. Within an estimated median follow-up of 13 years, patients assigned as IHC basal "nestin+ or INPP4B-" had significantly better overall survival on gemcitabine-docetaxel versus docetaxel monotherapy (HR = 0.31, 95%CI: 0.16-0.60), whereas no differences were observed for other patients (HR = 0.99), p-interaction < 0.01. In the metastatic setting, women with IHC basal breast cancers defined as "nestin+ or INPP4B-" have superior overall survival when randomized to gemcitabine-containing chemotherapy compared to docetaxel alone. These findings need to be validated using larger prospective-retrospective phase III clinical trials series.

Longitudinal enumeration and cluster evaluation of circulating tumor cells improve prognostication for patients with newly diagnosed metastatic breast cancer in a prospective observational trial.

BACKGROUND: Circulating tumor cells (CTCs) carry independent prognostic information in patients with metastatic breast cancer (MBC) on different lines of therapy. Moreover, CTC clusters are suggested to add prognostic information to CTC enumeration alone but their significance is unknown in patients with newly diagnosed MBC. We aimed to evaluate whether longitudinal enumeration of circulating tumor cells (CTCs) and CTC clusters could improve prognostication and monitoring of patients with metastatic breast cancer (MBC) starting first-line therapy. METHODS: This prospective study included 156 women with newly diagnosed MBC. CTCs and CTC clusters were detected using CellSearch technology at baseline (BL) and after 1, 3, and 6 months of systemic therapy. The primary end point was progression-free survival (PFS) and the secondary end point overall survival (OS). Median follow-up time was 25 (7-69) months. RESULTS: There were 79 (52%) and 30 (20%) patients with ≥ 5 CTCs and ≥ 1 CTC cluster at baseline, respectively; both factors were significantly associated with impaired survival. Landmark analyses based on follow-up measurements revealed increasing prognostic hazard ratios for ≥ 5 CTCs and CTC clusters during treatment, predicting worse PFS and OS. Both factors added value to a prognostic model based on clinicopathological variables at all time points and ≥ 5 CTCs and presence of CTC clusters enhanced the model's C-index to > 0.80 at 1, 3, and 6 months. Importantly, changes in CTCs during treatment were significantly correlated with survival and patients with a decline from ≥ 5 CTCs at BL to < 5 CTCs at 1 month had a similar odds ratio for progression to patients with < 5 CTCs at BL and 1 month. Stratification of patients based on CTC count and CTC clusters into four groups (0 CTCs, 1-4 CTCs, ≥ 5 CTCs, and ≥ 1 CTC + CTC clusters) demonstrated that patients with CTC clusters had significantly worse survival compared to patients without clusters. CONCLUSIONS: Longitudinal evaluation of CTC and CTC clusters improves prognostication and monitoring in patients with MBC starting first-line systemic therapy. The prognostic value increases over time, suggesting that changes in CTC count are clinically relevant. The presence of CTC clusters adds significant prognostic value to CTC enumeration alone. TRIAL REGISTRATION: NCT01322893 . Registered on 25 March 2011.