Targeting cancer-derived extracellular vesicles by combining CD147 inhibition with tissue factor pathway inhibitor for the management of urothelial cancer cells

BACKGROUND

Extracellular vesicles (EVs), including microvesicles, hold promise for the management of bladder urothelial carcinoma (BLCA), particularly because of their utility in identifying therapeutic targets and their diagnostic potential using easily accessible urine samples. Among the transmembrane glycoproteins highly enriched in cancer-derived EVs, tissue factor (TF) and CD147 have been implicated in promoting tumor progression. In this in vitro study, we explored a novel approach to impede cancer cell migration and metastasis by simultaneously targeting these molecules on urothelial cancer-derived EVs.

METHODS

Cell culture supernatants from invasive and non-invasive bladder cancer cell lines and urine samples from patients with BLCA were collected. Large, microvesicle-like EVs were isolated using sequential centrifugation and characterized by electron microscopy, nanoparticle tracking analysis, and flow cytometry. The impact of urinary or cell supernatant-derived EVs on cellular phenotypes was evaluated using cell-based assays following combined treatment with a specific CD147 inhibitor alone or in combination with a tissue factor pathway inhibitor (TFPI), an endogenous anticoagulant protein that can be released by low-molecular-weight heparins.

RESULTS

We observed that EVs obtained from the urine samples of patients with muscle-invasive BLCA and from the aggressive bladder cancer cell line J82 exhibited higher TF activity and CD147 expression levels than did their non-invasive counterparts. The shedding of GFP-tagged CD147 into isolated vesicles demonstrated that the vesicles originated from plasma cell membranes. EVs originating from invasive cancer cells were found to trigger migration, secretion of matrix metalloproteinases (MMPs), and invasion. The same induction of MMP activity was replicated using EVs obtained from urine samples of patients with invasive BLCA. EVs derived from cancer cell clones overexpressing TF and CD147 were produced in higher quantities and exhibited a higher invasive potential than those from control cancer cells. TFPI interfered with the effect when used in conjunction with the CD147 inhibitor, further suppressing homotypic EV-induced migration, MMP production, and invasion.

CONCLUSIONS

Our findings suggest that combining a CD147 inhibitor with low molecular weight heparins to induce TFPI release may be a promising therapeutic approach for urothelial cancer management. This combination can potentially suppress the tumor-promoting actions of cancer-derived microvesicle-like EVs, including collective matrix invasion.

Proteomic analyses identify HK1 and ATP5A to be overexpressed in distant metastases of lung adenocarcinomas compared to matched primary tumors

Lung cancer is the leading cause of cancer-related deaths worldwide with lung adenocarcinoma (LUAD) being the most common type. Genomic studies of LUAD have advanced our understanding of its tumor biology and accelerated targeted therapy. However, the proteomic characteristics of LUAD are still insufficiently explored. The prognosis for lung cancer patients is still mostly determined by the stage of disease at the time of diagnosis. Focusing on late-stage metastatic LUAD with poor prognosis, we compared the proteomic profiles of primary tumors and matched distant metastases to identify relevant and potentially druggable differences. We performed high-performance liquid chromatography (HPLC) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) on a total of 38 FFPE (formalin-fixed and paraffin-embedded) samples. Using differential expression analysis and unsupervised clustering we identified several proteins that were differentially regulated in metastases compared to matched primary tumors. Selected proteins (HK1, ATP5A, SRI and ARHGDIB) were subjected to validation by immunoblotting. Thereby, significant differential expression could be confirmed for HK1 and ATP5A, both upregulated in metastases compared to matched primary tumors. Our findings give a better understanding of tumor progression and metastatic spreads in LUAD but also demonstrate considerable inter-individual heterogeneity on the proteomic level.

Molecular profiling and specific targeting of gemcitabine-resistant subclones in heterogeneous pancreatic cancer cell populations

Purpose

Chemotherapy is pivotal in the multimodal treatment of pancreatic ductal adenocarcinoma (PDAC). Technical advances unveiled a high degree of inter- and intratumoral heterogeneity. We hypothesized that intratumoral heterogeneity (ITH) impacts response to gemcitabine treatment and demands specific targeting of resistant subclones.

Methods

Using single cell-derived cell lines (SCDCLs) from the classical cell line BxPC3 and the basal-like cell line Panc-1, we addressed the effect of ITH on response to gemcitabine treatment.

Results

Individual SCDCLs of both parental tumor cell populations showed considerable heterogeneity in response to gemcitabine. Unsupervised PCA including the 1,000 most variably expressed genes showed a clustering of the SCDCLs according to their respective sensitivity to gemcitabine treatment for BxPC3, while this was less clear for Panc-1. In BxPC3 SCDCLs, enriched signaling pathways EMT, TNF signaling via NfKB, and IL2STAT5 signaling correlated with more resistant behavior to gemcitabine. In Panc-1 SCDCLs MYC targets V1 and V2 as well as E2F targets were associated with stronger resistance. We used recursive feature elimination for Feature Selection in order to compute sets of proteins that showed strong association with the response to gemcitabine. The optimal protein set calculated for Panc-1 comprised fewer proteins in comparison to the protein set determined for BxPC3. Based on molecular profiles, we could show that the gemcitabine-resistant SCDCLs of both BxPC3 and Panc-1 are more sensitive to the BET inhibitor JQ1 compared to the respective gemcitabine-sensitive SCDCLs.

Conclusion

Our model system of SCDCLs identified gemcitabine-resistant subclones and provides evidence for the critical role of ITH for treatment response in PDAC. We exploited molecular differences as the basis for differential response and used these for more targeted therapy of resistant subclones.

Panomics reveals patient individuality as the major driver of colorectal cancer progression

BACKGROUND

Colorectal cancer (CRC) is one of the most prevalent cancers, with over one million new cases per year. Overall, prognosis of CRC largely depends on the disease stage and metastatic status. As precision oncology for patients with CRC continues to improve, this study aimed to integrate genomic, transcriptomic, and proteomic analyses to identify significant differences in expression during CRC progression using a unique set of paired patient samples while considering tumour heterogeneity.

METHODS

We analysed fresh-frozen tissue samples prepared under strict cryogenic conditions of matched healthy colon mucosa, colorectal carcinoma, and liver metastasis from the same patients. Somatic mutations of known cancer-related genes were analysed using Illumina's TruSeq Amplicon Cancer Panel; the transcriptome was assessed comprehensively using Clariom D microarrays. The global proteome was evaluated by liquid chromatography-coupled mass spectrometry (LC‒MS/MS) and validated by two-dimensional difference in-gel electrophoresis. Subsequent unsupervised principal component clustering, statistical comparisons, and gene set enrichment analyses were calculated based on differential expression results.

RESULTS

Although panomics revealed low RNA and protein expression of CA1, CLCA1, MATN2, AHCYL2, and FCGBP in malignant tissues compared to healthy colon mucosa, no differentially expressed RNA or protein targets were detected between tumour and metastatic tissues. Subsequent intra-patient comparisons revealed highly specific expression differences (e.g., SRSF3, OLFM4, and CEACAM5) associated with patient-specific transcriptomes and proteomes.

CONCLUSION

Our research results highlight the importance of inter- and intra-tumour heterogeneity as well as individual, patient-paired evaluations for clinical studies. In addition to changes among groups reflecting CRC progression, we identified significant expression differences between normal colon mucosa, primary tumour, and liver metastasis samples from individuals, which might accelerate implementation of precision oncology in the future.

Abstract P5-04-16: Total estrogenic activity during neoadjuvant therapy with letrozole and exemestane – An intra-patient cross-over comparison using the AroER tri-screen

Background. Aromatase inhibitors (AIs), letrozole (Femarâ / Femaraâ) and exemestane (Aromasinâ), are widely used anti-hormonal drugs for breast cancer. Both compounds strongly reduce circulating estradiol levels in postmenopausal women. In the setting of metastatic breast cancer, these drugs may be used after another, causing new responses in selected patients by switching to the alternative drug after progressing on the first choice. This well-known ”lack of cross resistance” has been recognized for some time and is documented by several clinical trials. However, the precise explanation for this clinical observation is still unknown. The availability of mechanistic information may lead to an improved strategy against hormone-sensitive breast cancer.

Patients and methods. NEO-LET-EXE was a neoadjuvant, randomized, open-label, intra-patient cross-over trial. Postmenopausal patients with estrogen receptor (ER) positive (>50%), HER-2 negative, locally advanced breast cancer were enrolled. Sequential blood samples (obtained at baseline, after 2 months and 4 months of treatment) were available from 29 patients. All patients were randomized to sequential treatment starting with either letrozole (2.5 mg o.d.) or exemestane (25 mg o.d) for 2 months followed by another 2 months on the alternative compound. The total estrogenic activities in the collected blood samples were determined using AroER tri-screen assay developed by the Chen laboratory. The assay utilizes MCF-7aro ERE cells which contain both aromatase and ER. The samples were assayed in the presence as well as the absence of letrozole, to estimate relative contributions of estrogen and estrogen+androgen to the activities, respectively.

Results. Using the highly sensitive AroER tri-screen assay, estrogenic activity were detected at three time points in all blood samples. Importantly, a significantly higher total estrogenic activity was found during therapy with exemestane compared to letrozole in 23 out of 26 patients. Only in three patients, the activity was higher during therapy with letrozole compared to exemestane. When letrozole was included in the assay, the estrogenic activities in most samples collected during exemestane treatment were further reduced, suggesting that low levels of androgen were present in samples from exemestane treatment. Four samples collected after exemestane treatment and three after letrozole treatment had higher activities than baseline samples when assay was carried out with letrozole.

Discussion. Our results suggest the AroER tri-screen to be a very sensitive method to estimate the overall estrogen-mediated activity in human samples. Significant higher levels of estrogenic activity in human serum were observed during exemestane than those during letrozole treatment. Our observations, that additional letrozole could reduce further the estrogen activity in the exemestane-treated samples, demonstrate probably residual aromatase activity during therapy with exemestane alone.In addition to distinguish the effects of exemestane and letrozole, our results also demonstrate that the assay can also potentially detect the effects of estrogenic mimics.

Citation Format: Bahrami N, Chang G, Kanaya N, Sauer T, Gravdehaug B, Chen S, Geisler J. Total estrogenic activity during neoadjuvant therapy with letrozole and exemestane – An intra-patient cross-over comparison using the AroER tri-screen [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-04-16.

Abstract OT1-01-01: The NEO-LET-EXE-trial: An intra-patient cross-over trial to explore the "lack of cross-resistance" between steroidal and non-steroidal aromatase inhibitors

Background. The aromatase inhibitor letrozole and the aromatase inactivator exemestane currently belong to the most widely used antihormonal drugs for breast cancer worldwide. Both compounds are strongly suppressing estradiol levels in postmenopausal patients with breast cancer. However, in the metastatic setting, these drugs may be used after another, causing new responses in selected patients following switching to the alternative drug after progressing on the first choice. This well-known “lack of cross resistance” has been recognized for some time and is documented by several trials. However, the precise explanation for this clinical observation is still unknown. The solution may potentially lead us to a novel strategy to treat hormone-sensitive breast cancer.

Trial design. NEO-LET-EXE is a neoadjuvant, randomized, open-label, intra-patient cross-over trial .

Eligibility criteria. Postmenopausal patients suffering from estrogen receptor (ER) positive (>50%), HER-2 negative, locally advanced breast cancer, suitable for neoadjuvant/presurgical antihormonal therapy, may be enrolled. Age: 18+ (no upper limit).

Specific aims. To explain the phenomenon of a lack of cross-resistance between steroidal and non-steroidal aromatase inhibitors in vivo. Sequential tumor biopsies and blood samples, obtained at baseline and following 2 months of therapy with each drug given in sequence, will be used to perform a comprehensive exploration of the consequences of each drug therapy. The influence on plasma and tissue steroids (estrogens, androgens, etc.) will be compared. In addition, whole genome sequencing, whole exome sequencing, epigenetics, proteomics and plasma analysis (cytokines, tumor DNA fragments, etc.) will be performed.

Statistical methods. Data will be analyzed using mixed effects models.

Present accrural and target accrural. 49 out of planned 100 patients have been enrolled so far. The last patient is expected to enter the trial in Q4 2019.

Citation Format: Bahrami N, Sauer T, Loeng M, Gravdehaug B, Engebretsen SS, Aljabri B, Bemanian V, Lindstrøm JC, Lüders T, Kristensen VN, Geisler J. The NEO-LET-EXE-trial: An intra-patient cross-over trial to explore the "lack of cross-resistance" between steroidal and non-steroidal aromatase inhibitors [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT1-01-01.

Abstract P3-06-11: Time-course DNA and RNA profiling of tumors from intra-patient cross-over trial of sequential use of aromatase inhibitors

Background. The NEO-LET-EXE trial examines the neoadjuvant use of sequential administration of the aromatase inhibitor letrozole (Femar / Femara) and the aromatase inactivator exemestane (Aromasin). Although both drugs nearly completely inhibit aromatase, resistance to both is developed with time. However, when used sequentially, in some patients after switching to the alternative drug and progressing on the first choice, new responses may appear. The mechanism behind this clinical observation is currently not known. The solution may lead to a novel strategy to re-sensitize tumors to hormonal treatment. Prior studies have examined genomics at the four month time point, but not at both two months and four months.

Material. Postmenopausal patients with estrogen receptor (ER) positive (>50%), HER-2 negative locally advanced breast cancer may be enrolled. Age: 18+ (no upper limit). Present accrural and target accrural: 49 out of planned 100 patients have been enrolled so far. The last patient is expected to enter the trial in Q4 2019.

Study design. In the neoadjuvant, randomized, open-label, intra-patient cross-over trial NEO-LET-EXE biopsies are taken before treatment, after two months on one aromatase inhibitor and swap to the other aromatase inhibitor, and at surgery at four months.

Results. In order to explain the phenomenon of a lack of cross-resistance between steroidal and non-steroidal aromatase inhibitors we profiled biopsies at three time points per patient by whole exome and whole transcriptome sequencing from FFPE from 25 patients. A total of 56 DNA whole exomes and 41 RNA seq transcriptomes were generated from FFPE samples available. When grouping both arms together, mutational burden decreased at two months, while clonality of mutations increased, providing evidence of selection. At four months, mutational burden increased from the two month timepoint. In particular, PIK3CA somatic variants present at the first time point were not detected at two months. However, these were detected again at significant variant allele fractions at four months after switch of treatment. The majority of gene expression changes happen in the initial two months, with fewer changes between two and four months. Instead, significant changes in alternative splicing at two months and four months were observed, for example for FGFR1, which does not experience a large fold change in expression between these two points. Our preliminary results show significant DNA and RNA changes in the first two months of aromatase inhibition leading to fewer, more clonal variants. Comparison of the four month to two month time point shows fewer RNA changes than the prior two months and an increase in the number of somatic variants compared to the two month timepoint.

Citation Format: Vaske CJ, Parulkar R, Bahrami N, Sauer T, Loeng M, Gravdehaug B, Aljabri B, Bemanian V, Lindstrøm J, Lüders T, Kristensen V, Geisler J. Time-course DNA and RNA profiling of tumors from intra-patient cross-over trial of sequential use of aromatase inhibitors [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-06-11.

Prevalence and impact of asthma among school-aged students in Lima, Peru

SETTING AND OBJECTIVE

The International Study of Asthma and Allergies in Childhood (ISAAC) reported asthma prevalence in Peru to be among the highest in the world. We assessed the prevalence and morbidity of self-reported asthma in an underserved, peri-urban area of Lima, Peru, with limited medical access.

DESIGN

The study was conducted in the outskirts of Lima from March to May 2011. Five hundred children aged 6-18 years were selected through cluster sampling. Parents completed a modified version of the ISAAC questionnaire. Children underwent spirometry testing. Those with a forced expiratory volume in one second (FEV1% predicted) 80% were tested for reversibility using salbutamol.

RESULTS

Of the 500 children selected, 71% participated. The prevalence of asthma was 16.7%. Asthma symptoms were associated with self-reported asthma (P < 0.001); 52.5% of children with asthma had ever used an inhaler (P < 0.001), and 27.1% had never been to the doctor for respiratory problems (P < 0.001).

CONCLUSION

We found a high prevalence of self-reported asthma and high morbidity related to asthma symptoms in the previous 12 months among the study cohort. Symptoms were poorly controlled due to limited availability of medication and access to medical services.

Abstract P1-06-10: Next generation sequencing (NGS) reveals high mutation rates in all established breast cancer subtypes with subtype-specific patterns

Introduction. Next-generation sequencing (NGS) technologies offer the possibility for assessment of multiple genes for their somatic mutations and may elucidate the driver genetic variations involved in carcinogenesis and disease progression. Among the various subtypes of breast cancer (BC), the triple-negative subgroup (TNBC) is characterized by poor prognosis and a lack of reliable tumor markers when compared to the luminal-A/-B and HER-2 positive subtypes. The aim of this study was to characterize genetic variations in primary BC obtained from a cohort of 159 Norwegian patients using a NGS panel consisting of 44 BC relevant genes. Our goal was to compare the genetic variations between BC subtypes in general with special emphasis on the TNBC subtype (over 40% of the patients).

Methods. Genomic DNA was extracted from paraffin embedded formalin fixed (FFPE) tissue obtained from 160 consecutive patients diagnosed with a primary BC at our hospital. The DNA samples were analyzed by next-generation sequencing (NGS) using Human Breast Cancer GeneRead DNAseq Targeted Panel V2 (Qiagen). The panel consists of a collection of PCR primers for targeted enrichment of the coding region of 44 genes commonly mutated in BC. Target enrichment and library construction was performed according to the GeneReader workflow (Qiagen) and paired end sequencing was performed on a NextSeq 500 sequencer (Illumina) running 2 x 150 bp chemistry Version 2. Data analysis including alignment to the reference genome hg19 and variant calling was performed using Qiagen's online Ingenuity Variant analysis.

Results. The ingenuity variant analysis classified the genetic mutations according to their clinical significance into four groups: pathogenic, likely pathogenic, benign and likely benign. We present only mutations in genes that are characterized as pathogenic or likely pathogenic, where the term "likely pathogenic" indicates greater than 90% certainty of the mutation being pathogenic (as defined by the American College of Medical Genetics and Genomics). Genetic variations were mostly observed in a subset of 44 genes included in the breast cancer panel. The tumor suppressor genes TP53 as well as BRCA1 and BRCA2 represented the highest mutation rates (&gt;5%) among all BC samples. Interestingly, additional genes potentially playing a pivotal role in BC biology like EP300 were also found to be mutated at a high rate in TNBC. The biological significance of the EP300 gene remains unknown. Additionally, comparing the mutation rates of several genes like TP53, PIK3CA, BRCA2, ATM, RET and EGFR between established BC subtypes showed significant differences.

Conclusion. Next generation sequencing of samples obtained from primary breast cancer tumors confirmed a high level of pathogenic or likely pathogenic mutations in a subtype-specific pattern involving genes like TP53, BRCA1/2, ATM, EGFR, RB1 and PIK3CA.

Citation Format: Bemanian V, Sauer T, Joel T, Katja V, Vessela K, Ida B, Jürgen G. Next generation sequencing (NGS) reveals high mutation rates in all established breast cancer subtypes with subtype-specific patterns [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-06-10.

Abstract P3-05-08: Steroid receptors and steroidogenic enzymes in human breast cancer: Associations with breast cancer subtypes and clinical outcome

Introduction: The majority of breast cancer (BC) cases are believed to be highly steroid dependent. Therefore exploitation of currently untapped steroid pathways could potentially contribute to our search for novel targeted breast cancer therapies. Given the growing understanding of the importance of both intratumoral steroid metabolism and impact of alternate steroid receptors in BC biology, we evaluated selected steroidogenic pathways in a cohort of 140 BC cases from Akershus University Hospital, Norway. In this study we immunolocalized both the androgen receptor (AR) and glucocorticoid receptor (GR) in addition to steroid sulfatase (STS) and 17β hydroxysteroid dehydrogenase 2 (17βHSD2). We also evaluated immunoreactivity of Ki-67 and CYP19/aromatase. We correlated these factors with the occurrence of distant metastasis or local relapse, and survival adjusted by age at surgery. We also examined whether any of these pathways were enriched in the classical breast cancer subtypes (Luminal A, Luminal B, HER-2 positive, triple-negative BC). Logistic and Cox regression analysis was employed to examine interactions between the above factors.

Results: In an analysis looking at possible interactions between recurrence and the factors above, the status of intratumoral STS was significantly inversely associated with distant metastasis (OR=0.17, p&lt;0.001) and local relapses (OR=0.17, p&lt;0.001), while that of 17βHSD2 trended towards correlation with the presence of metastasis (OR=3.47, p=0.055) and relapse (OR=3.14, p=0.07). Interestingly, ER and PR were not correlated with metastasis or relapse, but HER2 status positively correlated with distant metastasis during follow-up (OR=2.15, p=0.02) and trended to be associated with local relapses as well (OR=1.99, p=0.054). When evaluated according to the established breast cancer subtypes the only significant changes detected between subgroups were for AR and STS. AR was positive in a lesser proportion of the cases in the TNBC subgrouping (p=0.01), while STS was depleted in the luminal B and enriched in the HER2 subtypes (p=0.027). In an analysis of survival, STS was the only factor examined that was significantly associated with survival outcomes of the patients. Positive intratumoral STS status was significantly associated with improved survival (HR=0.27, p&lt;0.001). The inverse of this was also noticed for 17βHSD2 but the correlation did not reach statistical significance (HR=2.1, p=0.16).

Discussion and Conclusions: The results of our present study suggest that the intratumoral metabolism of estrogens through STS is associated with significantly lower incidence of relapse and/or distant metastasis and correspondingly a better prognosis. The inverse is also true when evaluating the trends noted with the expression of 17βHSD2 adding consistency to our finding above. The enrichment of STS in the HER2 overexpressing subtype of breast cancer is intriguing, especially given the possible role of HER-2 positivity in endocrine resistance. All in all, our results suggest that extended endocrine information about the intratumoral steroid metabolism of a given tumour may have so far unused prognostic potential and impact on clinical decision making.

Citation Format: McNamara KM, Guestini F, Sauer T, Lindstrøm JC, Sasano H, Geisler J. Steroid receptors and steroidogenic enzymes in human breast cancer: Associations with breast cancer subtypes and clinical outcome [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-05-08.

CIN 2/3 and cervical cancer in an organised screening programme after an unsatisfactory or a normal Pap smear: a seven-year prospective study of the Norwegian population-based screening programme

Objectives: To estimate the risk of cervical intraepithelial neoplasia (CIN) 2/3 and invasive cervical cancer (ICC) in an organised screening programme after an unsatisfactory or a normal Pap smear.

Setting: A seven-year prospective cohort study of the Norwegian population-based co-ordinated screening programme based on the actual diagnostic and screening procedures performed. Observations of 526,661 women with a normal index Pap smear and 21,405 women with an unsatisfactory index Pap smear were made during 3.26 million women-years.

Methods: The risk of being diagnosed with CIN 2/3 or ICC was calculated by logistic regression for the first two years of follow-up. The hazard of being diagnosed with CIN 2/3 or ICC for the women who were not diagnosed during the two first years was estimated by non-parametrical survival regression.

Results: After two years of follow-up, 0.2% of the women were diagnosed with CIN 2/3 and 0.01% with ICC after a normal Pap smear. An unsatisfactory Pap smear indicated a 1.6-4.0 times higher risk of harbouring a CIN 2/3 or ICC compared to women with a normal Pap smear. No increased risk of ICC was found during long-term follow-up for the 70% of the women with an unsatisfactory Pap smear who were returned to ordinary screening. Prior series of low-grade Pap smears followed by a normal Pap were associated with an increased risk of CIN 2/3 and ICC.

Conclusions: An unsatisfactory Pap smear indicates a risk of harbouring CIN II/III or ICC. Repeated Pap smears are adequate as a follow-up of an unsatisfactory Pap smear. Women with repeated series of equivocal/LSIL Pap smears followed by a normal Pap should be considered at high risk.

Outcome of allogeneic stem cell transplantation for AML and myelodysplastic syndrome in elderly patients (⩾60 years)

Allogeneic stem cell transplantation (SCT) remains the best curative option for patients with refractory AML or with high-risk myelodysplastic syndrome (MDS). For decades, age alone had been widely used as the primary criterion to assess eligibility for allogeneic SCT; however, prospective studies to evaluate allogeneic SCT in elderly patients are still limited. A total of 187 patients (median age of 64 years, range 60-77 years) with AML (87%) or MDS (13%) transplanted between 1999 and 2014 were included in this retrospective analysis. Relapse-free survival (RFS) and overall survival (OS) at 3 years were 32% (95% confidence interval (CI): 25-39%) and 35% (95%CI: 27-42%), respectively. Overall survival was 49% (95%CI: 35-64%) in AML patients who were transplanted in first complete remission (CR1), but even patients with active disease did benefit from transplantation, showing an OS at 3 years of 30% (95%CI: 20-40%). Multivariate analysis revealed disease- and patient-specific risk indices as independent prognostic factors for OS and non-relapse mortality (NRM). In conclusion, our monocenter results indicate that patients should not be generally withheld from allogeneic SCT because of age or disease status only. Specific risk models incorporating disease status and disease-specific risk factors at the time of transplantation as well as existing comorbidities are helpful tools to assess transplantation-associated risk factors of elderly patients.

Chronic adverse events and quality of life after radiochemotherapy in anal cancer patients. A single institution experience and review of the literature

PURPOSE

To report on chronic adverse events (CAE) and quality of life (QOL) after radiochemotherapy (RCT) in patients with anal cancer (AC).

PATIENTS AND METHODS

Of 83 patients who had received RCT at our department between 1988 and 2011, 51 accepted the invitation to participate in this QOL study. CAE were evaluated using the Common Terminology Criteria for Adverse Events (CTCAE) v. 4.0 and QOL was assessed with the Functional Assessment of Cancer Therapy-Colorectal (FACT-C) questionnaire.

RESULTS

CAE could be evaluated in 49 patients. There was a tendency toward a higher rate of grade 3 CAE in female patients, i.e. 18 out of 37 (49 %) vs. 2 out of 12 (17 %) male patients (p = 0.089). The most common grade 3 CAE were dyspareunia and vaginal symptoms (itching, burning and dryness) in 35 and 22 % of female patients, respectively, followed by stool incontinence in 13 % of all patients (6 out of 49). Both FACT-C and CAE information were available for 42 patients, allowing evaluation of the impact of CAE on QOL. The median total FACT-C score was 110 (40-132) out of a possible maximum of 136. The absence of grade 3 CAE (115 vs. 94, p = 0.001); an interval of ≥ 67 months after the end of the treatment (111 vs. 107, p = 0.010), no stool incontinence vs. grade 3 stool incontinence (111 vs. 74, p = 0.009), higher education (114 vs. 107, p = 0.013) and no dyspareunia vs. grade 3 dyspareunia (116 vs. 93, p = 0.012) were significantly associated with a higher median FACT-C score.

CONCLUSION

The majority of AC patients treated with RCT have acceptable overall QOL scores, which are comparable to those of the normal population. Patients with grade 3 CAE-particularly dyspareunia and fecal incontinence-have a poorer QOL compared to patients without CAE. In order to improve long-term QOL, future strategies might aim at a reduction in dose to the genitalia and more intensive patient support measures.

Characterization of patients with recurrent ischaemic stroke using the ASCO classification

BACKGROUND AND PURPOSE

The ASCO score has the advantage of allowing a more comprehensive characterization of ischaemic stroke patients and their risk factors, as reflected in different grades of evidence of atherosclerotic changes (A), small vessel disease (S), potential cardiac (C) or other (O) sources. It might also help to characterize patients with recurrent ischaemic stroke and document the etiology of stroke recurrence as well as the further development of risk factor constellations.

METHODS

We prospectively screened our stroke database for patients with recurrent ischaemic stroke between 2004 and 2011, and classified each stroke using ASCO. The distribution of etiologies was analysed, and changes in the ASCO score were documented for each patient.

RESULTS

We identified 131 patients with recurrence of ischaemic stroke. At the first event, the distribution of etiologies and their grade of evidence was 97 grade 1 (A = 18/S = 32/C = 44/O = 3), six grade 2 (A = 2/S = 1/C = 3/O = 0), 199 grade 3 (A = 85/S = 83/C = 23/O = 8), 204 grade 0 (A = 26/S = 14/C = 44/O = 120) and 18 grade 9 (A = 0/S = 1/C = 17/O = 0). At stroke recurrence, 98 grade 1 (A = 16/S = 24/C = 55/O = 3), 11 grade 2 (A = 2/S = 5/C = 4/O = 0), 210 grade 3 (A = 94/S = 92/C = 13/O = 11), 171 grade 0 (A = 16/S = 9/C = 26/O = 117) and 34 grade 9 (A = 0/S = 1/C = 33/O = 0) were identified. Analysis of each individual showed a modification of the score in 85 patients (64.9%).

CONCLUSIONS

Recurrent ischaemic stroke does not always have the same etiology as the previous one(s). Among variable changes of grade 1 etiologies, an increasing prevalence of cardioembolism--often insufficiently treated--at stroke recurrence was a major finding. ASCO proved to be highly useful to monitor risk factor constellations.

Diagnostic terminology for reporting thyroid fine needle aspiration cytology: European Federation of Cytology Societies thyroid working party symposium, Lisbon 2009

A European Federation of Cytology Societies (EFCS) working party of 28 members from 14 European countries met at the European Congress of Cytology in Lisbon in September 2009, with two observers from the USA, to discuss the need for standardising thyroid FNA nomenclature in the light of the National Institute of Cancer (NCI) recommendations resulting from the State of the Science conference in Bethesda in 2007. The data were obtained through two questionnaires sent by email and a transcript of the live discussion at the congress, which is presented in full. The surveys and discussion showed that there were currently no national terminologies for reporting thyroid FNA in the different European countries except in Italy and the UK. Personal, 'local', surgical pathology and descriptive terminologies were in use. All but one of the working party members agreed that thyroid FNA reporting should be standardised. Whilst almost a third would adopt the NCI Bethesda terminology, which offers the advantages of a 'risk of cancer' correlation and is linked to clinical recommendations, more than half favoured a translation of local terminology as the first step towards a unified nomenclature, as has been done recently in the UK. There was some disagreement about the use of: a) the six-tiered as opposed to four or five-tiered systems, b) the use of an indeterminate category and c) the 'follicular neoplasm' category, which was felt by some participants not to be different from the 'suspicious of malignancy' category. The conclusions will be passed to the different national societies of cytology for discussion, who will be asked to map their local terminologies to the Bethesda classification, observe its acceptance by clinicians and audit its correlation with outcome.

Survey of medical training in cytopathology carried out by the journal Cytopathology

This report of the Editorial Advisory Board of Cytopathology gives the results of a survey of medical practitioners in cytopathology, which aimed to find out their views on the current situation in undergraduate and postgraduate training in their institutions and countries. The results show that training in cytopathology and histopathology are largely carried out at postgraduate level and tend to be organized nationally rather than locally. Histopathology was regarded as essential for training in cytopathology by 89.5% of respondents and was mandatory according to 83.1%. Mandatory cytopathology sections of histopathology were reported by 67.3% and specific examinations in cytopathology by 55.4%. The main deficiencies in training were due to its variability; there were insufficient numbers of pathologists interested in cytology and a consequent lack of training to a high level of competence. Pathologists without specific training in cytopathology signed out cytology reports according to 54.7% of responses, more often in centres where training was 3-6 months or less duration. Although 92.2% of respondents thought that specialist cytology should not be reported by pathologists without experience in general cytopathology, that practice was reported by 30.9%, more often in centres with small workloads. The survey report recommends that 6-12 months should be dedicated to cytopathology during histopathology training, with optional additional training for those wanting to carry out independent practice in cytopathology. Formal accreditation should be mandatory for independent practice in cytopathology. When necessary, temporary placements to centres of good practice should be available for trainees intending to practise independently in cytopathology. There should be adequate numbers of pathologists trained in cytopathology to a high level of competence; some of their time could be released by training cytotechnologists and trainee pathologists to prescreen cytology slides and assess adequacy of fine-needle aspiration samples when immediate diagnosis was not required. The survey demonstrated a clear need for European and international guidelines for training in cytopathology.

Prognostic implications of isolated tumour cells and micrometastasis in lymph nodes in non-adjuvant treated breast cancer patients

Abstract #205

Introduction : The status of axillary lymph nodes (ALNs) is the most powerful predictor of survival and has clinical implications for adjuvant treatment of breast cancer patients. Occult metastases in ALNs of patients initially staged as negative have been detected up to 40%, using the various methods with serial sectioning and/or immunohistochemical (IHC) staining. However, there is no consensus concerning the prognostic significance for occult metastases. The aim of this study was to estimate the prognostic value of isolated tumor cells (ITC, ≤0.2 mm) and micrometastases (MM, 0.2-2.0 mm) in invasive breast cancer.&#x2028; Materials and Methods: The ALNs of 295 patients with axillary node-negative invasive breast cancer treated from 1995 to 1998 was evaluated with serial sectioning and cytokeratin IHC (a single section from each of 10 levels) and hematoxylin-eosin (one section from 3rd and 10th level). Disseminated tumor cell status in bone marrow was also known. Of 295 patients, 232 were offered no systemic adjuvant therapy. Patients were categorized by largest cluster size (≤0,2mm, 0.2-2.0mm), and then their survival rates, i.e. disease-free survival (DFS), distant disease-free survival (DDFS) and breast cancer specific survival (BCSS) were compared with those of node-negative patients. We also investigated the correlation between occult metastases in ALNs and bone marrow (BM).&#x2028; Results: The median patient age was 59 years and the median tumour size was 1.5 cm. At a median observation time of 98 months (9-127 months), 33 patients had developed relapse,2 local and 31 systemic. 17 patients had died of breast cancer. Occult metastases were found in 92 of 295 patients (31%); ITC – 58% (53/92), MM -34% (31/92) and macrometastases (&gt;2.0mm)- 8% (8/92). The cases with macrometastases were excluded from survival analysis. The results presented in the table below demonstrate significant prognostic impact of MM on BCSS, borderline significance on DFS and DDFS. This was not shown for ITC. No significant correlation was found between occult metastases in ALN and BM in both total patients (Χ2-test, p=0.680).&#x2028; &#x2028; Conclusions: Our observation of a prognostic impact of MM in non-adjuvant treated patients indicates that adjuvant therapy might be warranted in this group. Lack of a similar finding in patients with ITC questions the need of adjuvant therapy in this group. The lack of correlation between occult metastases in ALN and BM indicates different “homing” mechanisms for the two compartments.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 205.

Diagnostic accuracy of fine-needle aspiration cytology in histological grade 1 breast carcinomas: are we good enough?

BACKGROUND

Fine-needle aspiration cytology (FNAC) of both palpable and non-palpable breast carcinomas has a high accuracy and sensitivity in dedicated centres. It is generally thought that low-grade carcinomas have a distinctly lower sensitivity due to discrete cellular atypia that may be difficult to appreciate. Grade 1 carcinomas make up about 45% of screening-detected breast carcinomas and about 20% of symptomatic breast cancers. The aim of this study was to evaluate the diagnostic sensitivity of grade 1 carcinomas and identify the critical features in the cytological diagnostic work-up of these tumours.

METHODS

There were FNAC smears from 494 histologically confirmed grade 1 carcinomas diagnosed during 1996-2004. The cytological diagnoses were compared with the histology.

RESULTS

A definitive malignant diagnosis (absolute sensitivity) was given in 382 cases (77.3%). Equivocal or suspicious diagnoses were given in 75 (15.2%), benign or probably benign (false negative) in 24 (4.8%). Thirteen cases (2.6%) were unsatisfactory. Complete sensitivity was 92.7%. Invasive ductal carcinomas comprised 81.3% of all cases; absolute sensitivity for these was 80.9%. Invasive lobular and tubular carcinomas comprised 7.3% and 5.9% of cases, respectively; absolute sensitivity for these diagnosis was 50.0% and 57.1%, respectively, significantly lower than for other subtypes (P <or= 0.0001) whereas the difference for complete sensitivity was less but still significant (P = 0.017). Absolute and complete sensitivities were lower for tumours less than 1 cm size compared with more than 1 cm (P <or= 0.00001).

CONCLUSION

Preoperative FNAC diagnosis of grade 1 breast carcinoma has a high sensitivity, especially in ductal carcinomas. Invasive lobular and tubular carcinomas were less likely to receive a definite preoperative diagnosis. The main reason for not reaching a definitive malignant diagnosis was sampling error due to small tumours less than 1 cm in diameter, irrespective of tumour subtype.

Delay-coordinates embeddings as a data mining tool for denoising speech signals

In this paper, we utilize techniques from the theory of nonlinear dynamical systems to define a notion of embedding estimators. More specifically, we use delay-coordinates embeddings of sets of coefficients of the measured signal (in some chosen frame) as a data mining tool to separate structures that are likely to be generated by signals belonging to some predetermined data set. We implement the embedding estimator in a windowed Fourier frame, and we apply it to speech signals heavily corrupted by white noise. Our experimental work suggests that, after training on the data sets of interest, these estimators perform well for a variety of white noise processes and noise intensity levels.

Demonstration of EGFR gene copy loss in colorectal carcinomas by fluorescence in situ hybridization (FISH): a surrogate marker for sensitivity to specific anti-EGFR therapy?

AIMS

To investigate EGFR gene copy number heterogeneity in colorectal carcinomas compared with copy number of chromosome 7 and immunohistochemical expression of the EGFR protein.

METHODS AND RESULTS

Fluorescence in situ hybridization of the EGFR gene and CEP7 was carried out on paraffin-embedded material from 48 rectal carcinomas combined with immunohistochemical detection of EGFR with a polymer detection kit. EGFR gene copy number had a range of 1.4-7.3 with a mean of 2.5. CEP7 copy number had a range of 1.5-6.1 with a mean of 2.5. The EGFR gene/CEP7 ratio ranged from 0.4 to 1.5 with a mean of 0.96. Most cases had a balanced EGFR gene/CEP7 ratio (37 cases = 77%). Copy gain was found in seven cases (15%) with a ratio of up to 1.5, consistent with gain of one EGFR gene copy in one chromosome. Copy loss was found in four cases (8%). All cases with EGFR gene copy loss were immunohistochemically positive.

CONCLUSIONS

Demonstration of EGFR gene copy loss might be a surrogate marker for EGFR mutation/deletion and could be used in a routine setting in pathology departments. Further studies are needed to determine whether this may be used to select patients that might benefit from specific anti-EGFR therapy.

Reduced expression of Claudin-7 in fine needle aspirates from breast carcinomas correlate with grading and metastatic disease

OBJECTIVE

To study the immunocytochemical expression of the tight junction protein Claudin-7 in smears from breast carcinomas and correlate with grading, nodal status, locoregional and distant metastases and the cellular cohesion.

METHODS

The material consisted of 52 air-dried smears from fine needle aspirates of breast carcinomas, both primary and metastatic and smears from seven benign lesions. A primary antibody to Claudin-7 was used for immunocytochemical staining. The degree of staining was recorded as negative, reduced or full, with full expression meaning equivalent to the staining pattern found in the fibroadenomas used as benign control. Staining intensity and the percentage of stained cells were evaluated. The control smears revealed a strong membrane and cytoplasmic positivity in all luminal epithelial cells. Cellular cohesion was graded as: (1) mainly cohesive groups, (2) groups and single cells and (3) mainly single cells.

RESULTS

All primary and recurrent/metastatic breast lesions expressed Claudin-7. Full expression was demonstrated in 46% of the cases. Reduced expression was found in 54%. In cases with reduced expression, the percentage of stained cells were usually high, and no smear showed <50% stained tumour cells. The staining pattern was heterogeneous and always mixed membrane/cytoplasmic. Claudin-7 expression showed a significant correlation (P < 0.05) with grading, locoregional and distant metastases, nodal involvement and cellular cohesion in invasive carcinomas, but not with tumour size or subtype.

CONCLUSION

Reduced expression of Claudin-7 correlated with higher tumour grade, metastatic disease, including loco-regional recurrences and with cellular discohesion.

BSCC, Bethesda or other? Terminology in cervical cytology European panel discussion

The European panel agreed that reproducibility and translatability of terminology in cervical cytology were essential, arguing well for harmonization of reporting systems. The majority at this meeting use a modification of the Bethesda system (BS). Local modifications involved reporting subcategories within high grade and low grade lesions, which would not alter the overall translatability of their systems both with each other and BS. The majority agree that low grade lesions with and without koilocytosis should be managed similarly as should high grade lesions (moderate dysplasia/CIN2 or worse). Those systems linking moderate dysplasia with mild rather than severe dysplasia would need to define moderate dysplasia as such, if their results were to be translatable, which would be preferable to their using a different definition of low grade and high grade lesions. Translation between systems might anyway be facilitated by reporting moderate dysplasia as a subcategory within high grade, which was favoured by most of those present. Therefore, there is no need for exact agreement of terminology if broad principles are agreed. This useful discussion adds weight to the British Society for Clinical Cytology recommendation that the new classification should be adopted by the UK National Health Service Cervical Screening Programme. If the new classification is adopted, the UK would join the European consensus opinion on terminology.

Detection of isolated tumor cells in bone marrow is an independent prognostic factor in breast cancer

PURPOSE

This study was performed to disclose the clinical impact of isolated tumor cell (ITC) detection in bone marrow (BM) in breast cancer.

PATIENTS AND METHODS

BM aspirates were collected from 817 patients at primary surgery. Tumor cells in BM were detected by immunocytochemistry using anticytokeratin antibodies (AE1/AE3). Analyses of the primary tumor included histologic grading, vascular invasion, and immunohistochemical detection of c-erbB-2, cathepsin D, p53, and estrogen receptor (ER)/progesterone receptor (PgR) expression. These analyses were compared with clinical outcome. The median follow-up was 49 months.

RESULTS

ITC were detected in 13.2% of the patients. The detection rate rose with increasing tumor size (P =.011) and lymph node involvement (P <.001). Systemic relapse and death from breast cancer occurred in 31.7% and 26.9% of the BM-positive patients versus 13.7% and 10.9% of BM-negative patients, respectively (P <.001). Analyzing node-positive and node-negative patients separately, ITC positivity was associated with poor prognosis in the node-positive group and in node-negative patients not receiving adjuvant therapy (T1N0). In multivariate analysis, ITC in BM was an independent prognostic factor together with node, tumor, and ER/PgR status, histologic grade, and vascular invasion. In separate analysis of the T1N0 patients, histologic grade was independently associated with both distant disease-free survival (DDFS) and breast cancer-specific survival (BCSS), ITC detection was associated with BCSS, and vascular invasion was associated with DDFS.

CONCLUSION

ITC in BM is an independent predictor of DDFS and BCSS. An unfavorable prognosis was observed for node-positive patients and for node-negative patients not receiving systemic therapy. A combination of several independent prognostic factors can classify subgroups of patients into excellent and high-risk prognosis groups.

Logistics of referral, diagnostic assessment and treatment of patients with breast symptoms and signs

BACKGROUND AND AIMS

The logistics of diagnosis and treatment in a hospital with slightly above 400 new cases of breast cancer per year is analysed.

MATERIALS AND METHODS

The patient flow from referral, through the diagnostic procedures and through surgical treatment is described.

RESULTS AND CONCLUSIONS

The basic principle of the diagnostic assessment is the triple diagnostic procedure including mammography supplemented by ultrasonography, fine needle aspiration cytology and clinical examination. The radiologist and pathologist are working together in the breast diagnostic centre and are thus able to give a "single visit diagnosis" in most cases. The surgeon sees the patient either the same day or the next. A "consensus meeting" held each week with representatives for all specialities present has an important function in quality assurance and education. If one or more of the triple diagnostic components reach conclusion level "suspicious lesion", surgery is indicated. In hospital management is based on day surgery for all biopsies, wide excisions with or without sentinel node and some ablatio simplex mammae. For wide excision and ablation with complete axillary node clearance, the patients are transferred from the day surgery unit to a patient hotel after 3-4 hours of observation and stay till the drain can be removed. Only in rare case of high cardiopulmonary risk, beds in ordinary wards are used. This is a highly cost efficient logistic saving the hospital approximately 400,000 EUR a year compared to ordinary in hospital treatment.

Immunocytochemical expression of E-cadherin on fine-needle aspirates from breast carcinomas correlate with the cell dissociation pattern seen on smears

Altered E-cadherin expression has been suggested to be of prognostic significance in breast cancers and to correlate with tumor subtype and grade. A dysfunctional, intercellular adhesion system may be responsible for the tumor cell dissociation pattern seen on fine-needle aspirate cytology (FNAC). The aim of our study was to determine E-cadherin expression on direct FNAC smears from breast carcinomas and compare the results with the dyscohesion grade of the tumor cells and the cytological grading. The material consisted of FNAs from 56 breast carcinomas. The degree of cellular cohesion was estimated semiquantitatively. Full expression of E-cadherin was defined as a complete and strong membrane staining of virtually all tumor cells. All nonductal as well as 85% of the invasive ductal carcinomas revealed reduced expression or negativity for E-cadherin. In all, 25% of carcinomas with dyscohesion Grade 1 (mainly in groups) revealed full expression of E-cadherin, in contrast to 12.5% of tumors with dyscohesion Grade 3 (mainly dispersed cells). Nuclear positivity was seen in 21% of the tumors (12 cases) and seven of these were G3 ductal carcinomas. In conclusion, E-cadherin expression correlated with the cell dissociation pattern seen on direct smears from FNAC of breast carcinomas, but is only one of several markers that modulate this pattern. High-grade carcinomas rarely revealed full expression and had a high incidence of aberrant nuclear localization of E-cadherin.

Detection of isolated tumor cells in bone marrow in early-stage breast carcinoma patients: comparison with preoperative clinical parameters and primary tumor characteristics

PURPOSE/EXPERIMENTAL DESIGN: The importance of detection of disseminated isolated tumor cells (ITCs) in bone marrow (BM) is still not settled. BM aspirates from 920 patients with primary breast cancer were analyzed for tumor cells by standardized direct immunocytochemical analysis (ICC) of 2 x 10(6) mononuclear cells (MNCs) using anticytokeratin monoclonal antibody (AE1/AE3). Samples (637) were analyzed by negative immunomagnetic enrichment (IMS) followed by ICC (10 x 10(6) MNCs). Analyses of the primary tumor specimens have been performed, including histomorphology, tumor-node-metastasis (TNM) staging, grading, and immunohistochemical analyses.

RESULTS

Of the patients with infiltrating carcinoma, 63% were node negative (N0) and 33%, node positive (N+). The results show the presence of tumor cells in 13.4% of the evaluable patients after direct ICC analysis. The presence of tumor cells correlated to the nodal- and tumor stage, showing BM positivity in 9.9% of the N0 cases and 20.6% in the N+ group (P < 0.0005), 11.2% of the stage T(1) were positive, and 15.0% and 22.6% were positive in the T(2) and T(3/4) groups, respectively (P = 0.013). No correlation between detection of ITC and detection of p53 and cathepsin D expression was found. Vascular invasion and c-erbB2 expression were associated with ITCs in BM (P = 0.045 and P = 0.024, respectively). Node-negative patients with estrogen receptor (ER)+ and/or progesterone receptor (PgR)+ tumors had lower frequency of ITCs than ER-/PgR- (P = 0.004). The use of negative IMS increased the frequency of positive BM by 63% (P < 0.0005).

CONCLUSIONS

The direct ICC detection of ITCs in BM correlated with primary tumor stage, nodal stage, vascular invasion, c-erbB2 expression, and ER/PgR status. Analysis of larger BM samples by negative IMS resulted in increased number of ITC-positive patients.

Physicochemical analysis of purified diphtheria toxoids: is toxoided then purified the same as purified then toxoided?

Diphtheria toxin can be converted into a highly immunogenic and irreversibly detoxified vaccine either using the conventional process in which the crude toxin is formalinised and subsequently purified (DTxd(conv)) or by detoxification of the highly purified toxin (DTxd(new)). In this study, both DTxd(new) and DTxd(conv) were evaluated by use of physico-chemical methods. For some methods, results were also compared to those obtained for cross-reacting material (CRM197), which is a non-toxic mutant of diphtheria toxin. DTxd(new) was assayed to have a specific purity of at least 2300 LF/mg protein N, thereby exceeding Pharm. Eur. requirements by up to 35%. Superior purity of DTxd(new) could also be demonstrated by size exclusion HPLC experiments and by amino acid composition studies. Far-UV circular dichroism spectroscopy revealed that the secondary structure of DTxd(new) almost resembled that of CRM197, suggesting only minor molecular changes during detoxification. This study worked out differences between purified diphtheria toxoids. Physico-chemical means revealed the advantages of DTxd(new) being the purer and more defined product, thus making it highly efficient for its use as a vaccine carrier as well as a component of vaccine combinations.