MUC1 Antigen Research Articles

KL-6, a human MUC1 mucin, is expressed early in premature lung

KL-6, one of the MUC1 antigens, is a mucin-like high-molecular-weight glycoprotein, which is strongly expressed on type II pneumocytes. Serum levels of KL-6 have been shown to correlate with activity of interstitial pneumonia (IP). During embryonic development, MUC1 expression coincides with the onset of epithelial sheet and glandular formation. To investigate the potential role of KL-6 in lung morphogenesis, we examined KL-6 expression by immunohistochemistry on autopsied lung tissue specimens of 35 neonates and infants with gestational age from 23 to 40 weeks. Hyaline membranes (HMs) were detected in 13 of 35 cases. Simultaneously, antibody against surfactant protein A (SP-A) was employed in the study which is a distinct marker for type II pneumocytes. In all cases studied with gestational age above 23 weeks, staining for KL-6 was strongly positive in alveolar epithelial cells and in HMs found in 13 cases, whereas immunoreaction for PE10 varied depending on gestational age and duration of postnatal survival. Our findings suggest that KL-6 is expressed earlier in premature lung and may act as an important factor contributing to morphogenesis and function of developing lung in early gestation.

Complex carbohydrates are not removed during processing of glycoproteins by dendritic cells: processing of tumor antigen MUC1 glycopeptides for presentation to major histocompatibility complex class II-restricted T cells.

In contrast to protein antigens, processing of glycoproteins by dendritic cells (DCs) for presentation to T cells has not been well studied. We developed mouse T cell hybridomas to study processing and presentation of the tumor antigen MUC1 as a model glycoprotein. MUC1 is expressed on the surface as well as secreted by human adenocarcinomas. Circulating soluble MUC1 is available for uptake, processing, and presentation by DCs in vivo and better understanding of how that process functions in the case of glycosylated antigens may shed light on antitumor immune responses that could be initiated against this glycoprotein. We show that DCs endocytose MUC1 glycopeptides, transport them to acidic compartments, process them into smaller peptides, and present them on major histocompatability complex (MHC) class II molecules without removing the carbohydrates. Glycopeptides that are presented on DCs are recognized by T cells. This suggests that a much broader repertoire of T cells could be elicited against MUC1 and other glycoproteins than expected based only on their peptide sequences.

Dendritic Cell–Tumor Cell Fusion and Staphylococcal Enterotoxin B Treatment in a Pancreatic Tumor Model

Background. Surgical resection of pancreatic tumors removes gross disease but not metastases. Adjuvant therapy such as chemotherapy and radiation treatment is of little value in metastatic pancreatic cancer. The hypothesis of this investigation is that specific and effective immunotherapeutic vaccine (dendritic/tumor cell fusion) will activate cytotoxic T lymphocytes (CTLs), leading to the eradication of spontaneous pancreatic cancer. Methods. We have developed a double transgenic mouse model (MET) that forms spontaneous pancreatic tumors and expresses the human MUC1 antigen. Seven-week-old MET mice ( n = 8) were treated every 3 weeks with the vaccine. In addition, these mice received 50 μg of superantigen staphylococcal enterotoxin B (SEB), a known T cell stimulant, prior to the first vaccination. A second treatment group received SEB alone ( n = 8) and controls received no treatment ( n = 9). MUC1-specific CTLs were measured by chromium release assay. At 10 weeks of age and at necropsy, MUC1 serum levels were measured using a MUC1-specific ELISA. Results. Mice were known to harbor microscopic foci of cancer at birth. Survival was enhanced in vaccine as well as SEB-treated mice (75% CI ± 0.42) compared to controls (11% CI ± 0.28) and both groups of treated mice exhibited mature CTLs without in vitro stimulation. MUC1 serum levels of the vaccine group were 50% less than that of control ( P < 0.04) at 10 weeks. MUC1 serum levels directly correlated with tumor weight at necropsy ( r = 0.86). Conclusions. This is the first evidence that MUC1-specific CTLs can be stimulated to enhance survival in a spontaneous tumor model.

Constitutive and Inducible Expression of the Epithelial Antigen MUC1 (CD227) in Human T Cells

MUC1 (CD227) is a large glycoprotein normally produced by epithelial tissue and expressed aberrantly in carcinomas. Here we show that resting human T cells express basal levels of MUC1 mRNA and protein forms with molecular masses of ∼150 and ∼250 intracellularly, but lack surface expression. Mitogenic stimulation induces the appearance of new MUC1 mRNA and >300-kDa MUC1 forms. Concomitantly, MUC1 is translocated to the outer cell membrane and its density is continuously modulated according to the cycling status. Inhibitors of mRNA and protein synthesis and of Golgi-dependent protein transport prevent MUC1 induction. Ligation of surface MUC1 has no effect on T-cell proliferation. Also, altering the overall protein structure by preventing glycosylation has no effect. Sizable amounts of >300-kDa glycosylated MUC1 forms are shed by proliferating T cells. This soluble MUC1 does not appear to influence T-cell response, and we found no evidence for MUC1 binding sites on T cells or for transfer of the protein on cell–cell contact. We therefore suggest that MUC1 fulfills the criteria for an early T-cell activation marker but its function remains to be determined. Finally, although we found that cancer- and T cell-associated MUC1 expose common protein core and sialylated epitopes, there is a peptide region, accessible in carcinomas due to an aberrant glycosylation, that is stably not accessible in T cells with potential implications for cancer immunotherapy.

MUC1 expression is correlated with nuclear grade and tumor progression in pT1 renal clear cell carcinoma.

We studied, by immunohistochemical analysis, the expression of MUC1 and epithelial membrane antigen in 44 stage pT1 renal cell carcinomas (RCCs). Six patients had a metastatic evolution. The percentage of stained cells was determined for each tumor. All tumors and normal adjacent renal parenchyma were stained. In normal kidney, distal convoluted tubules and collecting ducts stained strongly with an apical distribution. In tumors, there was a significant statistical correlation of the MUC1 expression level with the nuclear grade and with tumor progression. High-grade tumors had more stained cells than did low-grade tumors. Metastatic tumors also were more stained than nonmetastatic lesions. By using the Kaplan-Meier method and the log-rank test, we observed that patients with fewer than 10% of stained cells had no metastatic evolution. In contrast, patients with 70% or more stained cells had significantly lower metastasis-free survival rates. We conclude that MUC1 is expressed in RCC and is associated with tumor progression in pT1 RCC.

Antigenic and immunologic characterization of an allogeneic colon carcinoma vaccine.

We report the immunological characterization of three colon carcinoma cell lines, COLO 205, SW620 and SW403, which we selected to combine with cytokine-secreting fibroblasts for the development of an allogeneic tumour cell vaccine. The cell lines expressed HLA-A2 as well as shared tumour-associated antigens (TAAs) representative of colon carcinomas: CEA, Ep-CAM, MUC1, HER2/neu and MAGE antigens. They did not secrete high levels of the immunosuppressive factors TGF-beta, IL-10 or prostaglandins. The lines presented TAAs in a manner recognized by immune effector cells, which was demonstrated by the lysis of SW620 by HLA-A2-restricted anti-p53 cytotoxic T lymphocytes (CTL). COLO 205 and SW620 were genetically modified to express the co-stimulatory molecule CD80 (B7.1), which increased the ability of the cells to stimulate CTL in vitro. CTL clones derived from HLA-A2+ peripheral blood mononuclear cells stimulated with the CD80-expressing lines lysed the stimulator cell and an HLA-A2+ colon cancer cell line, but did not lyse an isogeneic fibroblast line or an HLA-A2- colon cancer cell line. CTL clones derived from colon carcinoma patients immunized with an allogeneic vaccine containing these lines demonstrated killing of autologous tumour cells, the vaccine cell lines and other HLA-A2+ colon cancer cell lines, but not fibroblasts isogeneic to certain of the target cell lines. Our studies demonstrate that these colon carcinoma cell lines express shared TAAs that can induce CTLs which recognize and lyse other colon carcinoma cells, and support the continued clinical evaluation of the CD80 gene modified allogeneic colon cell/cytokine-secreting fibroblast carcinoma vaccine.

Crystal Structure of a Non-canonical Low-affinity Peptide Complexed with MHC Class I: A New Approach For Vaccine Design

Peptides bind with high affinity to MHC class I molecules by anchoring certain side-chains (anchors) into specificity pockets in the MHC peptide-binding groove. Peptides that do not contain these canonical anchor residues normally have low affinity, resulting in impaired pMHC stability and loss of immunogenicity. Here, we report the crystal structure at 1.6Å resolution of an immunogenic, low-affinity peptide from the tumor-associated antigen MUC1, bound to H-2Kb. Stable binding is still achieved despite small, non-canonical residues in the C and F anchor pockets. This MUC1/Kb structure reveals how low-affinity peptides can be utilized in the design of novel peptide-based tumor vaccines. The molecular interactions elucidated in this non-canonical low-affinity peptide MHC complex should help uncover additional immunogenic peptides from primary protein sequences and aid in the design of alternative approaches for T-cell vaccines.

Novel vaccination protocol consisting of injecting MUC1 DNA and nonprimed dendritic cells at the same region greatly enhanced MUC1-specific antitumor immunity in a murine model.

In order to induce specific antitumor immunity in mice, we attempted to immunize C57BL/6 mice with DNA vaccine encoding MUC1 polypeptide. When the mice immunized with MUC1 DNA were challenged with EL4-muc, MUC1-transfected syngeneic lymphoma cells, they completely rejected tumors. When DNA vaccine was given to the EL4-muc tumor-bearing mice, this vaccination was insufficient to suppress tumor growth in the mice. However, activated, but nonprimed dendritic cells (DCs) obtained from syngeneic mice and MUC1 DNA vaccine were given simultaneously to the same site of EL4-muc tumor-bearing mice, tumor growth was markedly suppressed accompanying prolongation of survival time. MUC1 antigen was detected on the DCs at the vaccination site and in regional nodes in the mice which received MUC1 DNA vaccine and DCs. These mice showed markedly enhanced cellular immune responses specific for MUC1 compared to those in mice vaccinated with MUC1 DNA alone. No significant difference in titers of antibodies to MUC1 between the two groups was observed. These results suggest that nonprimed DCs inoculated at the DNA vaccine site are essential for eliciting strong antitumor cellular immunity to suppress tumor growth efficiently in DNA-vaccinated mice. This animal model is useful for developing DNA vaccine for anti-cancer immunotherapy.

Comparison of the biologic effects of MA5 and B-B4 monoclonal antibody labeled with iodine-131 and bismuth-213 on multiple myeloma.

Using a specific monoclonal antibody (MAb), B-B4, coupled to bismuth-213 ((213)Bi) by a chelating agent (CITC-DTPA), the feasibility of alpha-radioimmunotherapy (RIT) for multiple myeloma (MM) has been demonstrated previously. In this study, the two MAbs tested, MA5 and B-B4, target the epithelial antigens Muc-1 and syndecan-1, respectively, which are both expressed by MM cell lines. Antibody characterization was evaluated by flow cytometric analysis of normal and tumoral hematopoeitic cells of MM patients as well as immunohistochemical tests of normal, nonhematopoetic tissues. Radiobiologic effects were evaluated for (213)Bi- and iodine-131 ((131)I)--labeled antibodies. We assessed in vitro mortality (thymidine incorporation, MTT, and clonogenic assays) and cell cycle modifications with propidium iodide staining. These tests were performed on MM cell lines until 120 hours postirradiation at several time points, using radiolabeled antibody concentrations ranging from 0.5 to 20 nM and specific activities ranging from 240 to 1200 MBq/mg of MAb. MA5 stained all MM cells in only 50% of patients, whereas B-B4 recognized all MM cells in all patients. B-B4 principally showed hepatic, pulmonary, and duodenal staining, whereas MA5 marked renal and pulmonary tissues. RIT with (213)Bi-B-B4 induced specific mortality and G(2)/M phase cell cycle arrest, which depended on the concentrations and specific activity. For (213)Bi-MA5, this arrest appeared at concentrations above 10 nM, an amount fivefold higher than that required with B-B4. This difference was also found in thymidine incorporation assays. Furthermore, with (213)Bi-B-B4, the arrest at the G(2)/M phase appeared quickly, within 24 hours after irradiation, and affected up to 60% of the cells (for 20 nM of (213)Bi-B-B4 at 1,200 MBq/mg). Conversly, (131)I-B-B4 had a very limited effect on cell mortality and did not induce any cell cycle arrest. The results of this study show that B-B4 might be the more effective therapeutic antibody and suggest that alpha-RIT might be more suitable than beta-RIT for treating single-cell tumor models. Thus, these findings set the stage for the beginning of clinical trials using alpha-emitter--radiolabeled B-B4, with special attention paid to hepatic, pulmonary, and intestinal side effects.

Immunoreactivity of Lewis blood group and mucin peptide core antigens: correlations with grade of dysplasia and malignant transformation in the colorectal adenoma-carcinoma sequence.

Previous studies on the immunoreactivity of various mucin peptide and carbohydrate antigens in neoplastic colorectal tissues led to at least in part contradictory results. Therefore, we investigated a series of 42 adenomas and 44 carcinomas applying monoclonal antibodies (mabs) directed against Lewis blood group antigens (sialyl-Le(a), Le(x), sialyl-Le(x), Le(y)) as well as mucin peptide cores (MUC1, MUC2 and MUC5AC) by immunohistochemistry. A statistically significant positive correlation between the development of high-grade dysplasia in colorectal adenomas and the immunoreactivity of Le(y) and MUC1 epitopes was observed, whereas MUC2 exhibited a significant negative correlation. The reactivity of the other epitopes did not show an association with the progression of malignant transformation. Colorectal carcinomas were subdivided according to their histopathological subtype. The immunohistochemical staining resulted in a significantly stronger MUC2 reactivity of mucinous vs. tubular adenocarcinomas. Immunoreactivity of the MUC1-specific mab, which does not react with the fully glycosylated peptide core, showed a statistically non-significant inverse tendency, whereas all carbohydrate antigens displayed a strong expression in both tumor subtypes. Furthermore, correlations between mucin peptide and carbohydrate epitope labelling were evaluated. Progression of the adenoma-carcinoma sequence was accompanied by an increase of Le(y) as well as MUC1 antigen and an increase of all Lewis antigens compared to MUC2 immunoreactivity. On the other hand, mucinous carcinomas exhibited an inverse pattern. In conclusion, these results demonstrate that Le(y) and MUC1 immunoreactivity correlate with malignant transformation in the colorectum, whereas MUC2 represents a marker for low-grade dysplasia and the subtype of mucinous carcinomas.

Vaccination with allogeneic dendritic cells fused to carcinoma cells induces antitumor immunity in MUC1 transgenic mice.

Fusions of autologous tumor cells with allogeneic dendritic cells (DC) represent an approach for the induction of antitumor immunity. In the present studies, we investigated the antitumor effects of vaccinating MUC1-transgenic (MUC1.Tg) mice with MC38/MUC1 carcinoma cells fused to allogeneic DC from BALB/c mice (allo-DC, H-2(d)) or syngeneic DC from C57BL/6 mice (syn-DC, H-2(b)). Both allo and syn fusion cells (FC/MUC1) expressed MHC class II, costimulatory molecules, and the MUC1 antigen. Allo-FC/MUC1 exhibited dual expression of MHC class I haplotypes (H-2(d)/H-2(b))and MUC1 antigen. By contrast, only H-2(b) and MUC1 antigen were expressed by syn-FC/MUC1. CTLs from MUC1.Tg mice immunized with allo- or syn-FC/MUC1 fusion cells lysed MC38/MUC1 targets. Moreover, immunization with allo- or syn-FC/MUC1 was effective in eliminating established MUC1-positive pulmonary metastases in MUC1.Tg mice. These results indicate that immunization of MUC1.Tg mice with syn- or allo-FC/MUC1 is effective in reversing immunologic unresponsiveness to MUC1 antigen and inducing immunity against MUC1-positive tumors. The findings in the present study have broader clinical implications for fusion cell vaccines.

Novel MUC1 Splice Variants Are Expressed in Cervical Carcinoma

Objectives. The MUC1 antigen can be used to identify epithelial cells from the background of hemopoietic cells. The present investigation describes patterns of overexpression of two novel MUC1 splice variants in human cervical carcinoma cell lines.Methods. RT-PCR was carried out to determine MUC1 splice variants in the cervical cancer cell lines C-4 II, C-33A, DoTc 2 4510, C-4 I, SiHa, HT3, Hs 636 T (C4-I), and HeLa.Results. The novel MUC1 splice variant D was expressed in all cell lines and the novel MUC1 splice variant C was expressed in all cell lines but C-33A. Variants A and B were expressed in all (variant A) and all but one (variant B) cell line. MUC1/REP was expressed in all cell lines and MUC1/SEC was positive in all but two cell lines (C-33 A, DoTc 2 4510). All but one cell line (C-33A) expressed MUC1/X and MUC1/Y, and two cell lines (C-33 A, DoTc 2 4510) did not express MUC1/Z, respectively. MUC1 variants A, D, and REP could be demonstrated consistently among all eight cervical carcinoma cell lines we have examined.Conclusions. The present study describes the feasibility of detecting a large number of MUC1 variants, including MUC1 variants C and D which are described for cervical carcinoma cells for the first time. Further studies will examine the presence of MUC1 splice variants' expression in human cervical carcinoma tissue.

Expression of MUC1 and MUC2 mucins and relationship with cell proliferative activity in human colorectal neoplasia.

Our previous studies on MUC1 and MUC2 mucin expression in various human neoplasms have found that MUC1 expression is related with a poor outcome whereas MUC2 expression is related with a favorable outcome. In the present study, we examined the alteration of MUC1 and MUC2 antigens on malignant transformation of colorectal mucosa, and also its relationship with cell proliferative activity (Ki-67 labeling index) of neoplastic epithelial cells in 200 adenomas and 58 carcinomas. In the 200 adenomas, we analyzed a total of 400 adenomatous lesions (mild dysplasia, 200 lesions; moderate dysplasia, 153 lesions; severe dysplasia, 47 lesions). MUC1 was expressed in carcinomas (24%) and adenomas with severe dysplasia (4%), but was not expressed in adenomas with mild or moderate dysplasia. MUC2 was expressed in a significantly greater number of adenomas with mild dysplasia (72%) than in adenomas with moderate dysplasia (45%) or severe dysplasia (47%), as well as in the carcinomas (38%; P < 0.0001). The Ki-67 labeling index was significantly lower in the MUC2-positive cases than in the MUC2-negative cases in the adenomas with mild dysplasia (13.6 vs 24.2%; P < 0.0001) or moderate dysplasia (25.7 vs 44.4%; P < 0.0001), and in the carcinomas (32.5 vs 48.4%; P < 0.05). In conclusion, the data from our study indicate that increased MUC1 expression and reduced MUC2 expression may be related to malignant transformation of colorectal neoplasia. We also demonstrated that decreased MUC2 expression, which is correlated with increased Ki-67 labeling, may play an important role in the progression of colorectal adenomatous change.

Characterization of an anti-MUC1 monoclonal antibody with potential as a cancer vaccine.

The monoclonal antibody (MAb) AR20.5 is a murine MAb, generated against the tandem repeat protein backbone of the tumor-associated antigen MUC1. MAb AR20.5 reacts strongly with either the soluble form or the cell surface epitope of MUC1 on many human cancer cell lines. It also reacts with a 23-amino acid MUC1 peptide, E23, which includes the core tandem repeat sequence. Epitope mapping confirmed that MAb AR20.5 recognizes a minimum of six residues with the sequence DTRPAP. Inhibition of glycosylation of MUC1 resulted in decreased binding of MAb AR20.5 to cell surface MUC1, suggesting that MAb AR20.5 binding is carbohydrate dependent. The antibody was studied in a human PBL-SCID/beige mouse model to evaluate its effect on progression of NIH:OVARCAR-3 tumors. Tumor reduction was observed in mice injected with MAb AR20.5, but not in mice treated with control murine antibody or PBS (p < 0.001 and p < 0.05, respectively). An anti-tumor effect could also be demonstrated in a CB6F1 mouse model with the MUC1 transfectoma 413BCR.

Vaccines in breast cancer

<h2>SUMMARY</h2> Several antigens recognized by cellular and humoral effectors of the immune system have been identified in breast cancer. ‘Cancer/Testis' antigens, e.g. MAGE, NY-ESO-1, CT-7; differentiation antigens, e.g. NY-BR-1, CEA; overexpressed antigens, e.g. p53, HER2/neu, MUC-1, LewisX; and mutational antigens, e.g. p53, represent potential targets for antigen-specific immunotherapy. Clinical vaccine studies, mostly performed in melanoma, and aimed at the induction of antigen-specific CD8+ T cell responses in vivo, have helped to establish sensitive tools for the monitoring of immune responses to the vaccine in vivo and in vitro. Delayed-type hypersensitivity (DTH) reactions observed after intradermal injection of antigenic peptides were found to closely correlate with the induction of antigen-specific CD8+ T cell responses. Cytokines (GM-CSF, IL-2, IL-12) and adjuvants (QS21, IFA, MHC class II restricted helper peptides) have mediated increased CD8+ T cell responses against different antigenic peptides. The site of immunization may have important implications for the quality of immune responses induced. Intradermal and intralymphatic vaccination has led to strong CD8+ T cell responses in vivo, measurable at the immunization site, in metastatic lesions and in the peripheral blood. Intravenous and subcutaneous vaccination have induced measurable immune responses less frequently. Different strategies of vaccination using dendritic cells loaded with antigenic peptides, proteins or lysates prepared from autologous or allogeneic tumour cells have also led to measurable immune responses in vivo. Results, however, were not superior to vaccination with antigenic peptides alone or combined with adjuvants. Focusing on breast cancer, one of the most promising antigens for the design of vaccine studies is the CT-antigen NY-ESO-1, which was identified by the SEREX method. NY-ESO-1 is expressed in approximately 30–50% of breast cancers. Spontaneous humoral and cellular immune responses against NY-ESO-1 can be detected in 50% of patients with NY-ESO-1+ tumours. Specific DTH- and CD8+ T cell responses were induced after vaccination with NY-ESO-1 derived peptides alone and combined with GM-CSF in the majority of NY-ESO-1-naive patients. Measurable immune responses that can be correlated with the clinical outcome represent an important prerequisite for any immunotherapeutic intervention in cancer immunotherapy. At present, measurable but limited disease will teach us about any immediate effects of immunotherapy on cancer cells. This will lead the way in the near future to sound and justified adjuvant treatment strategies in the specific immunotherapy of breast cancer.

Expression of MUC1 and MUC2 and carbohydrate antigen Tn change during malignant transformation of biliary papillomatosis.

Biliary papillomatosis is characterized by papillary proliferations of biliary lining cells without invasion or metastasis. The neoplastic character and biological behaviour of this disease remain still speculative. These issues were examined in this study. Mucin core protein MUC1, MUC2, MUC3, MUC5AC and carbohydrate antigens (T, Tn and sialosyl Tn) were immunohistochemically examined, using 11 lesions of biliary papillomatosis from seven patients, and five lesions of biliary papillomatosis with foci of carcinoma from four patients. Five cases of papillary intrahepatic cholangiocarcinoma and 12 histologically normal livers were used as a control. Patients with biliary papillomatosis alone or with carcinoma were middle-aged or elderly (five men and six women). Microscopically, biliary papillomatosis showed a villous, papillo-tubular, papillary, or papillo-villous pattern with a thin fibrovascular core. Cytologically, they were classifiable into biliary epithelial or pyloric gland-like type. The former was frequent in the cases associated with carcinoma. Expression of MUC1, Tn antigen and sialosyl Tn antigen was frequent and marked in biliary papillomatosis alone and with carcinoma and also intrahepatic papillary carcinoma. In addition, marked expression of MUC1 and Tn antigen were rather frequent in biliary papillomatosis with carcinoma and intrahepatic biliary papillary carcinoma compared with biliary papillomatosis. MUC2 was rather frequent and marked in biliary papillomatosis alone compared to other two disease groups. Focal expression of MUC5AC and MUC2 was rather frequent and infrequent irrespective of disease group, respectively. Focal expression of T antigen was frequent in papillary ICC. Biliary papillomatosis could undergo overt malignant transformation along with altered phenotypic expression of MUC proteins and mucin carbohydrate antigens.

Specific immunotherapy of MUC1-positive adenocarcinomas with a recombinant vaccinia virus expressing MUC1 and IL-2

Current therapies for most types of cancer focus on either surgical or radiotherapeutic eradication of the primary tumor as the best opportunity for cure. Therapy of disseminated disease has focused on chemotherapy, but, with the exception of certain rarer types of tumors, few patients are cured by chemotherapy, and even improvements in survival have been difficult to demonstrate. TRANSGENE's current approaches to oncology focus on the stimulation of the body's own immune system to induce rejection of tumors. One of these approaches is antigen-specific therapy. The first product candidate for antigen-specific therapy expresses the tumor-associated MUC1 antigen, stimulating a cellular immune response that may be useful in treating breast cancer and various epithelial cancers, such as lung, pancreatic and ovarian cancers. The product developed is a recombinant vaccinia virus containing sequences that code for human MUC-1 antigen and interleukin-2. A phase I trial in nine women with breast cancer was performed, in which the potential product was well tolerated without serious side effects, and MUC1-specific immune responses were observed. PhaseII trials in breast and in prostate cancer began during the second quarter of 1998. A phaseI trial in lung cancer patients is also in progress. During the same period, a second-generation product was developed. The new construct has been put into a highly attenuated vaccinia virus (modified virus Ankara), the safety of which was tested in a clinical trial in MUC1-positive cancer patients. Based on these results, phase II studies are in preparation to assess the clinical efficacy of this product in different populations of patients whose tumors express the MUC-1 tumor antigen.

G‐CSF induces elevation of circulating CA 15‐3 in breast carcinoma patients treated in an adjuvant setting

BACKGROUND Cancer antigen 15-3 (CA 15-3), a circulating marker that determines secreted products of the polymorphic MUC1 gene, has been established as a convenient tool for monitoring breast carcinoma patients. METHODS The authors investigated alterations of soluble CA 15-3 in 57 postoperative breast carcinoma patients while they were receiving intensified adjuvant chemotherapy with granulocyte colony stimulating factor (G-CSF) support; 26 patients had American Joint Committee on Cancer (AJCC) Stage II, and 31 patients had AJCC Stage III breast carcinoma. Serial CA 15-3 values recorded thoughout the treatment were compared with baseline values, analyzed for correlation with hematologic and biochemical parameters, and compared with clinicopathologic characteristics and patient outcome. At a median follow-up time of 32 months, 47 of these patients remained relapse-free. RESULTS A twofold increase of CA 15-3 was detected at the end of the second week of treatment, remained significantly elevated in most patients at above the cutoff level of 30 U/mL throughout the treatment period (P < 0.0001), and subsided to pretreatment values 1–2 months after treatment cessation. CA 15-3 values were found to be associated strongly with absolute neutrophil count, serum lactate dehydrogenase, and alkaline phosphatase. The median values and the kinetics of tumor markers did not differ over time in regard to hormonal receptor status and disease recurrence. CONCLUSIONS These data provide strong evidence that G-CSF administration can induce elevation of CA 15-3 and indicate that false-positive results should be considered when evaluating CA 15-3 in patients who are receiving G-CSF. It is speculated that this phenomenon occurs through the induction of MUC1 antigen of unknown origin by G-CSF. Experimental investigation of this clinical observation is warranted. Cancer 2001;91:909–17. © 2001 American Cancer Society.

Anti-MUC-1 immunoliposomal doxorubicin in the treatment of murine models of metastatic breast cancer

The fate of breast cancer patients is dependent upon elimination or control of metastases. We studied the effect of antibody-targeted liposomes containing entrapped doxorubicin (DXR) on development of tumours in two models of breast cancer, pseudometastatic and metastatic, in mice. The former used the mouse mammary carcinoma cell line GZHI, which expresses the human MUC-1 gene (L. Ding, E.N. Lalani, M. Reddish, R. Koganty, T. Wong, J. Samuel, M.B. Yacyshyn, A. Meikle, P.Y.S. Fung, J. Taylor-Papadimitriou, B.M. Longenecker, Cancer Immunol. Immunother. 36 (1993) 9–17). GZHI cells seed into the lungs of Balb/c mice following intravenous injection. The latter used the 4T1-MUC1 cell line, a MUC-1 transfectant of the mouse mammary carcinoma cell line 4T1, which metastasizes from a primary mammary fatpad (mfp) implant to the lungs (C.J. Aslakson, F.R. Miller, Cancer Res. 52 (1992) 1399-1405). B27.29, a monoclonal antibody against the MUC-1 antigen, was used to target sterically stabilized immunoliposomes (SIL[B27.29]) to tumour cells. In vitro, SIL[B27.29] showed high specific binding to both GZHI and 4T1-MUC1 cells. The IC50 of DXR-loaded SIL[B27.29] was similar to that of free drug for GZHI cells. In the pseudometastatic model, mice treated with a single injection of 6 mg DXR/kg in DXR-SIL[B27.29] at 24 h after cell implantation had longer survival times than those injected with non-targeted liposomal drug. In the metastatic model, severe combined immune deficiency mice given weekly injections×3 of 2.5 mg DXR/kg encapsulated in either targeted or non-targeted liposomes were almost equally effective in slowing growth of the primary tumour and reducing development of lung tumours. Surgical removal of the primary tumour from mfp, followed by various chemotherapy regimens, was attempted, but removal of the primary tumour was generally incomplete; tumour regrowth occurred and metastases developed in the lungs in all treatment groups. DXR-SL reduced the occurrence of regrowth of the primary tumour, whereas neither targeted liposomal drug or free drug prevented regrowth. We conclude that monoclonal antibody-targeted liposomal DXR is effective in treating early lesions in both the pseudometastatic and metastatic models, but limitations to the access of the targeted liposomes to tumour cells in the primary tumour compromised their therapeutic efficacy in treating the more advanced lesions.

G-CSF induces elevation of circulating CA 15-3 in breast carcinoma patients treated in an adjuvant setting

Cancer antigen 15-3 (CA 15-3), a circulating marker that determines secreted products of the polymorphic MUC1 gene, has been established as a convenient tool for monitoring breast carcinoma patients. The authors investigated alterations of soluble CA 15-3 in 57 postoperative breast carcinoma patients while they were receiving intensified adjuvant chemotherapy with granulocyte colony stimulating factor (G-CSF) support; 26 patients had American Joint Committee on Cancer (AJCC) Stage II, and 31 patients had AJCC Stage III breast carcinoma. Serial CA 15-3 values recorded thoughout the treatment were compared with baseline values, analyzed for correlation with hematologic and biochemical parameters, and compared with clinicopathologic characteristics and patient outcome. At a median follow-up time of 32 months, 47 of these patients remained relapse-free. A twofold increase of CA 15-3 was detected at the end of the second week of treatment, remained significantly elevated in most patients at above the cutoff level of 30 U/mL throughout the treatment period (P < 0.0001), and subsided to pretreatment values 1-2 months after treatment cessation. CA 15-3 values were found to be associated strongly with absolute neutrophil count, serum lactate dehydrogenase, and alkaline phosphatase. The median values and the kinetics of tumor markers did not differ over time in regard to hormonal receptor status and disease recurrence. These data provide strong evidence that G-CSF administration can induce elevation of CA 15-3 and indicate that false-positive results should be considered when evaluating CA 15-3 in patients who are receiving G-CSF. It is speculated that this phenomenon occurs through the induction of MUC1 antigen of unknown origin by G-CSF. Experimental investigation of this clinical observation is warranted.