Mucin-1 (repeated region)

Background: Chemotherapy is the standard of care for advanced stages of non-small-cell lung cancer (NSCLC). TG4010 is a targeted immunotherapy based on a poxvirus (modified vaccinia virus Ankara) that codes for MUC1 tumour-associated antigen and interleukin 2. This study assessed TG4010 in combination with first-line chemotherapy in advanced NSCLC. Methods: 148 patients with advanced (stage IIIB [wet] or IV) NSCLC expressing MUC1 by immunohistochemistry, and with performance status 0 or 1, were enrolled in parallel groups in this open-label, phase 2B study. 74 patients were allocated to the combination therapy group, and received TG4010 (10(8) plaque forming units) plus cisplatin (75 mg/m(2) on day 1) and gemcitabine (1250 mg/m(2) on days 1 and 8) repeated every 3 weeks for up to six cycles. 74 patients allocated to the control group received the same chemotherapy alone. Patients were allocated using a dynamic minimisation procedure stratified by centre, performance status, and disease stage. The primary endpoint was 6-month progression-free survival (PFS), with a target rate of 40% or higher in the experimental group. Analyses were done on an intention-to-treat basis. This study is completed and is registered with ClinicalTrials.gov, number NCT00415818. Findings: 6-month PFS was 43·2% (32 of 74; 95% CI 33·4-53·5) in the TG4010 plus chemotherapy group, and 35·1% (26 of 74; 25·9-45·3) in the chemotherapy alone group. Fever, abdominal pain, and injection-site pain of any grade according to National Cancer Institute Common Toxicity Criteria were more common in the TG4010 group than in the chemotherapy alone group: 17 of 73 patients (23·3%) versus six of 72 (8·3%), 12 (16·4%) versus two (2·8%), and four (5·5%) versus zero (0%), respectively. The most common grade 3-4 adverse events were neutropenia (33 [45·2%] of patients in the TG4010 plus chemotherapy group vs 31 [43·1%] in the chemotherapy alone group) and fatigue (18 [24·7%] vs 13 [18·1%]); the only grade 3-4 events that differed significantly between groups were anorexia (three [4·1%] vs 10 [13·9%]) and pleural effusion (none vs four [5·6%]). 38 of 73 patients (52·1%) in the TG4010 plus chemotherapy group and 34 of 72 (47·2%) in the chemotherapy alone group had at least one serious adverse event. Interpretation: This phase 2B study suggests that TG4010 enhances the effect of chemotherapy in advanced NSCLC. A confirmatory phase 2B-3 trial has been initiated. Funding: Transgene SA, Advanced Diagnostics for New Therapeutic Approaches (ADNA)/OSEO.

Using synthetic peptides 60,80, and 105 residues long, corresponding to 3, 4, and 5.25 tandem repeats of human mucin MUC-1 protein core, as antigens in a solid-phase enzyme-linked immunosorbent assay, we screened sera from 24 breast cancer patients, 10 colon cancer patients, and 12 pancreatic cancer patients, at various stages of disease, for the presence of mucin-specific antibodies. The 105-residue peptide was superior in allowing detection of high levels of anti-mucin antibodies in 10.9% of sera in each cancer group. Another 4.3% showed intermediate reactivity. Lower levels of detection were achieved with the 80-residue peptide, and no specific reactivity was detectable with the 60-residue peptide. Anti-mucin antibodies were previously undetectable when this assay was performed with purified whole mucin or short synthetic peptides. The presence or absence of antibody did not correlate with the levels of circulating mucin or stage of disease. One highly reactive serum sample was used to identify more precisely the epitope on the long synthetic peptide to which the reactivity was directed. The reactivity of this serum specific for the 105-residue peptide was blocked by a 9-residue peptide from the NH2-terminal region of the 20-residue tandem repeat containing the previously identified immunogenic epitope APDTRP. Another 9-residue mucin peptide, from the COOH-terminal region of the tandem repeat which does not contain the APDTRP epitope, had no effect. All the mucin-specific reactivity was found to be of the IgM isotype, indicating a helper T-cell-independent response, unusual for an antibody against a peptide epitope, but not unexpected for tandemly repeated epitopes.

An investigation was undertaken with the aim of studying the repetitive region of the MUC1 gene and analyzing its polymorphisms in some Italian sheep breeds. Two primers previously used for the goat MUC1 gene analyses allowed for the amplification of 4 different alleles. The sequence analysis showed that the repetitive region of the sheep MUC1 gene is an array of 60-bp repeats, in accordance with the information reported in humans, cattle, and goats. The polypeptide sequence encoded by the consensus repeat was very similar to the corresponding sequences of goats and cattle. The average homology of all repeated units was 82%; when the repeats were compared with the derived consensus repeat, homology dropped to 78%. The repeats were not all perfectly conserved, but the sequence homology was nevertheless clearly sufficient to preserve the mechanism giving rise to the variable-number tandem-repeat polymorphism. In spite of their reduced sequence homology, the sheep repeats shared a high number of potential glycosylation sites. The conservation of the exact number and position of glycosylation sites did not seem to be very important for the purpose of functional integrity, but glycosylation appeared to be conserved as a bulk property. Analysis of the polymorphism in 6 Italian breeds showed that the sheep repetitive region seemed to be less variable and smaller in size than the repetitive region of the goat. The findings of this study suggest that ruminants can be a useful model to study the mechanisms by which the variation in the repeat number and the extracellular domain size can modulate the effectiveness of MUC1 as a cell-surface shield.