A case with HER2-overexpressing breast cancer completely responded to humanized anti-HER2 monoclonal antibody.

This is a case report of a 57-year-old woman with a history of primary carcinoma of the right breast with metastases to the contralateral axillary lymph node. After a partial response (PR) was induced by high-dose chemotherapy with peripheral blood stem cell transplantation, she underwent mastectomy with biopsy of the bilateral axillary lymph nodes. Six months after surgery, the patient had multiple lung metastases. She was then treated with five cycles of fluorouracil, mitoxantrone and vindesine. Although a PR was achieved, further chemotherapy could not be given because of cardiac dysfunction. Since immunohistochemical staining for the HER2 gene product was strongly positive on the surface of primary tumor cells, humanized anti-HER2 monoclonal antibody (trastuzumab) was given intravenously. The metastatic lesion decreased in size and finally appeared to be only cicatricial. Twenty-one months after the initial administration of trastuzumab, the pulmonary lesion was excised. The pathological examination revealed no tumor cells in the resected specimen so further treatment was stopped. The relapse-free state has continued for 24 months after the pulmonary resection.     

Population pharmacokinetics of farletuzumab, a humanized monoclonal antibody against folate receptor alpha, in epithelial ovarian cancer

Purpose

The purpose of this analysis was to develop a population pharmacokinetic model for farletuzumab, a humanized immunoglobulin (Ig)G₁ monoclonal antibody (mAb) to the folate receptor alpha, which is a receptor over-expressed in ovarian cancer, but largely absent from normal tissue.

Methods

In total, 2,472 samples were included in the building of the pharmacokinetic model. Farletuzumab 12.5–400?mg/m² had been administered via intravenous infusion to 79 patients with advanced ovarian cancer enrolled in one of the two clinical studies. Data were analyzed by a nonlinear mixed-effects modeling approach.

Results

Farletuzumab pharmacokinetics was best described by a two-compartment model with first-order (linear) elimination. In the final model, estimated values of clearance and volume of distribution of the central compartment were 0.00784?l/h and 3.00?l, respectively. Body weight was the only covariate investigated that explained inter-patient variability in clearance and the central volume of distribution. There was no effect of age, human anti-human antibodies, or concomitant chemotherapy on the pharmacokinetics of farletuzumab. Simulations showed that, when the mg/kg/week dose was maintained, steady-state exposure to farletuzumab was similar with dosing every week or every 3?weeks.

Conclusions

The pharmacokinetic parameters of farletuzumab are similar to those of other IgG mAbs. The results support weight-based dosing of farletuzumab on a weekly or 3-weekly schedule.     

Dose escalation and pharmacokinetic study of a humanized anti-HER2 monoclonal antibody in patients with HER2/neu-overexpressing metastatic breast cancer

We conducted a phase I pharmacokinetic dose escalation study of a recombinant humanized anti-p185HER2 monoclonal antibody (MKC-454) in 18 patients with metastatic breast cancer refractory to chemotherapy. Three or six patients at each dose level received 1, 2, 4 and 8 mg kg(-1) of MKC-454 as 90-min intravenous infusions. The first dose was followed in 3 weeks by nine weekly doses. Target trough serum concentration has been set at 10 microg ml(-1) based on in vitro observations. The mean value of minimum trough serum concentrations at each dose level were 3.58 +/- 0.63, 6.53 +/- 5.26, 40.2 +/- 7.12 and 87.9 +/- 23.5 microg ml(-1) respectively. At 2 mg kg(-1), although minimum trough serum concentrations were lower than the target trough concentration with a wide range of variation, trough concentrations increased and exceeded the target concentration, as administrations were repeated weekly. Finally 2 mg kg(-1) was considered to be sufficient to achieve the target trough concentration by the weekly dosing regimen. One patient receiving 1 mg kg(-1) had grade 3 fever, one at the 1 mg kg(-1) level had severe fatigue defined as grade 3, and one at 8 mg kg(-1) had severe bone pain of grade 3. No antibodies against MKC-454 were detected in any patients. Objective tumour responses were observed in two patients; one receiving 4 mg kg(-1) had a partial response in lung metastases and the other receiving 8 mg kg(-1) had a complete response in soft tissue metastases. These results indicate that MKC-454 is well tolerated and effective in patients with refractory metastatic breast cancers overexpressing the HER2 proto-oncogene. Further evaluation of this agent with 2-4 mg kg(-1) weekly intravenous infusion is warranted.     

Trastuzumab as the lead monoclonal antibody in advanced breast cancer: choosing which patient and when

Trastuzumab is the first of the monoclonal antibodies to be used in the treatment of those patients who have HER2-positive metastatic breast cancer. It is most effective when combined with cytotoxics, such as the taxanes and vinorelbine. It is well-tolerated but associated cardiotoxicity makes use with anthracyclines and in patients with cardiac dysfunction problematic. A further adverse observation is that the rate of development of cerebral metastases is 2.8-times higher in patients who have received trastuzumab as part of their treatment regimens. Trastuzumab has been combined with cytotoxics, hormones, other monoclonal antibodies, such a pertuzumab and bevacizumab, and targeted small molecules such as lapatinib, and it can be conjugated with cytotoxics to deliver them to cancer cells. The dosage, duration of therapy and optimal combinations in advanced and early stage breast cancer and use after relapse are still being defined.     

Trastuzumab prolongs overall survival in patients with brain metastases from Her2 positive breast cancer

Background: Brain metastases are frequently encountered in Her2 positive advanced breast cancer. It is still not clear, if trastuzumab treatment should be continued following their diagnosis. In this analysis we evaluated if trastuzumab was able to influence time to in-brain progression (TTP) and overall survival (OS). For this reason, we compared patients who continued on trastuzumab with a historical control group. Patients and Methods: Seventeen Her2 positive patients receiving whole brain radiotherapy for brain metastases and continuing on trastuzumab were identified. As historical control group, thirty-six patients treated before 2002 were identified from a breast cancer database. We performed a multivariate analysis (Cox regression) to explore which factors were potentially able to significantly influence TTP and OS. Results: Median TTP was 6 months, range 1–33+ months. Median OS was 7 months, range 1–38 months. Seventeen patients received trastuzumab after WBRT. Factors associated with prolonged TTP were KPS (p = 0.001), and intensified local treatment (p = 0.004). A trend towards longer TTP was observed in patients treated with trastuzumab (p = 0.068). OS was significantly influenced by KPS (p < 0.001), and continued antibody therapy (p = 0.001). Conclusion: Two parameters were significantly associated with prolonged OS: KPS and trastuzumab. While there was a trend towards prolonged TTP in patients with trastuzumab treatment after WBRT, this did not reach statistical significance. It appears therefore reasonable to suggest continuation of antibody therapy in patients with good performance status despite disease spreading to the brain. Concerning activity of trastuzumab in brain metastases themselves, no final conclusion is possible.     

Serum enterolactone and postmenopausal breast cancer risk by estrogen, progesterone and herceptin 2 receptor status

Lignans are a group of estrogenic compounds present in plants. Several epidemiological studies proposed that lignans may protect against breast cancer by exerting anticarcinogenic activity. Levels of enterolactone were determined in serum samples of 1,250 cases and 2,164 controls from a large population-based case-control study. We assessed the association between serum enterolactone and postmenopausal breast cancer risk using conditional logistic regression accounting for potential risk and confounding factors. Fractional polynomials were used to determine the function that best fitted the data. Moreover, we assessed heterogeneity by estrogen/progesterone/herceptin (ER/PR/HER2) status of the tumor. Additionally, a meta-analysis with seven further studies addressing enterolactone concentrations and breast cancer risk was performed. Postmenopausal breast cancer risk decreased with increasing serum enterolactone levels [highest compared to lowest quintile: [odds ratio = 0.65; 95% confidence interval (CI) 0.52-0.83, p(trend) = < 0.0001]. A significant inverse association for ER+/PR+ as well as ER-/PR- tumors was observed, with a significantly stronger association for ER-/PR- tumors (p(heterogeneity) = 0.03). The association for ER-/PR- tumors did not differ by expression of HER2 (p(heterogeneity) = 0.3). The meta-analysis yielded a significant reduced pooled risk estimate of: 0.66; 95% CI: 0.55-0.77) comparing the highest to the lowest quantiles of enterolactone levels. We found strong evidence for a significant inverse association between serum enterolactone and postmenopausal breast cancer risk, which was stronger for ER-PR- than for ER+PR+ tumors but not differential by further expression of HER2. The overall evidence together with other studies supports an inverse association between higher serum enterolactone levels and postmenopausal breast cancer risk.     

Additive effects of a prolactin receptor antagonist,G129R,and herceptin on inhibition of HER2-overexpressing breast cancer cells

Genexol-PM is a novel Cremophor EL-free polymeric micelle formulation of paclitaxel. This single arm, multicenter phase II study was designed to evaluate the efficacy and safety of Genexol-PM in patients with histologically confirmed metastatic breast cancer (MBC). Forty-one women received Genexol-PM by intravenous infusion at 300 mg/m² over 3 h every 3 weeks without premedication until disease progression or intolerability. A total of 331 chemotherapy cycles were administered, with a median of 8 cycles per patient (range, 1–16). Overall response rate was 58.5% (95% CI: 43.5–72.3) with 5 complete responses and 19 partial responses. Thirty-seven patients who received Genexol-PM as a first-line therapy for their metastatic disease showed a response rate of 59.5% (95% CI: 43.5–73.7), and two responses were reported in four patients treated in the second-line setting for their metastatic disease. The median time to progression (TTP) for all patients was 9.0 months (range, 1.0–17.0+ months). Grade 3 non-hematologic toxicities included sensory peripheral neuropathy (51.2%), and myalgia (2.4%). Eight patients (19.5%) experienced hypersensitivity reactions, with grade 3 in two patients. Hematologic toxicities were grade 3 and 4 neutropenia (51.2 and 17.1%, respectively), and grade 1 and 2 thrombocytopenia (22.0%). Notably, no febrile neutropenia was observed. Genexol-PM appears a promising new paclitaxel in view of significant efficacies. Further trials with different dosing schedules, durations of delivery, or in combination with other drugs are warranted.     

Long-term remission of a Her2/neu positive primary breast cancer under double monoclonal antibody therapy with trastuzumab and bevacizumab

Background

The attempt to act on several signalling pathways involved in tumour development simultaneously appears to be more attractive than attacking a single target structure alone. Vascular endothelial growth factor (VEGF) over-expression is frequently observed in human epidermal growth factor receptor 2 (Her2/neu) positive patients with breast cancer and over-expression of the proto-oncogene Her2/neu is associated with an up-regulation of VEGF.

Case report

The case of a Her2/neu positive patient with breast cancer who refused cytotoxic chemotherapy with its potential side effects as well as mastectomy is presented. Our patient has been receiving the combined double administration of bevacizumab and trastuzumab for more than 4 years.

Conclusions

This case report shows that (a) the combined double administration of bevacizumab and trastuzumab was be clinically effective. (b) The combination of bevacizumab and trastuzumab is safe and non-toxic. (c) Bevacizumab and trastuzumab can be used as a long-term application.     

CNTO 859, a humanized anti-tissue factor monoclonal antibody, is a potent inhibitor of breast cancer metastasis and tumor growth in xenograft models

Thromboembolic complications are frequently associated with advanced cancer. Interestingly, one of the major initiators of blood coagulation, tissue factor (TF), is reported to be overexpressed in several tumor types and can be found on both tumor cells and tumor vasculature. Although the exact mechanisms have yet to be elucidated, TF expressed on tumor cells can trigger intracellular signaling events through various pathways that can lead to tumor angiogenesis, proliferation, and metastasis. There exists preclinical evidence that disruption of TF dependent signaling can effectively inhibit tumor cell migration, metastasis, and angiogenesis. Here, we report for the first time that an antibody to tissue factor can also prevent tumor growth in vivo. Prophylactic administration of CNTO 859, a humanized anti-human TF antibody, was shown to inhibit experimental lung metastasis of MDA-MB-231 human breast carcinoma cells by over 99% compared to a control antibody. Furthermore, therapeutic doses of CNTO 859 were shown to reduce tumor incidence and growth of orthotopically implanted MDA-MB-231 cells.     

ING-1(heMAb), a monoclonal antibody to epithelial cell adhesion molecule, inhibits tumor metastases in a murine cancer model

ING-1(heMAb), a human-engineered monoclonal antibody (MAb) that specifically targets the epithelial cell adhesion molecule (Ep-CAM), kills adenocarcinoma cells in vitro and inhibits tumor growth in vivo. In the current study, we evaluated the efficacy of ING-1(heMAb) in a murine model of cancer metastases. Mice received intravenous dosing of 1 mg/kg ING-1(heMAb), twice a week, starting on day 2 or day 5. A negative control group received 1 mg/kg human immunoglobulin G with the same dose frequency starting on day 2. A positive control group received weekly 100 mg/kg 5-flurouracil/leucovorin starting on day 2. ING-1(heMAb)/day 2 treatment significantly reduced both the number of visible tumor nodules in body cavities (P <.01) and the number of metastases on lung surfaces (P <.005). The treatment also resulted in a 91% reduction of micrometastases in lung tissues (P <.0001). Delaying ING-1(heMAb) treatment until day 5 caused 54% reduction in micrometastases (P <.005). Our results indicate that a number of parameters, including treatment starting day, dose level, and dose frequency, are critical in achieving the optimal efficacy of ING-1(heMAb). We conclude that ING-1(heMAb) effectively reduced tumor metastases in a murine cancer model. Immunotherapy with ING-1(heMAb) may be beneficial in treating human metastatic diseases.     

Safety, pharmacokinetics, immunogenicity, and biodistribution of (186)Re-labeled humanized monoclonal antibody BIWA 4 (Bivatuzumab) in patients with early-stage breast cancer

The aim of this prospective study was to evaluate the safety, pharmacokinetics, immunogenicity, and biodistribution of (186)Re-labeled humanized anti-CD44v6 monoclonal antibody (MAb( BIWA 4 (Bivatuzumab( in 9 patients with early-stage breast cancer. Radioimmunoscintigraphy (RIS( was performed within 1, 24, and 72 hours after administration. BIWA 4 concentration in plasma (ELISA and radioactivity measurements( and the development of human antihuman antibody (HAHA( responses was determined. The biodistribution of (186)Re-BIWA 4 was determined by radioactivity measurements in tumor and normal tissue biopsies obtained during surgery 1 week after administration. Administration of (186)Re-BIWA 4 was well tolerated by all patients and no HAHA responses were observed. The mean t(1/2) in plasma of BIWA 4 (ELISA( was 81 hours (range, 67-97(, whereas the mean radioactivity t(1/2) tended to be longer, at 105 hours (range, 90-114(. RIS unmistakably showed the tumor in 3 patients. Less clear identifications were established in 3 additional patients. In 2 patients, the tumor was wrongly identified in the contralateral breast. Median tumor CD44v6 expression, as determined by immunohistochemistry, was 70% (range, 10-90%). Mean tumor uptake was 2.96% ID/kg (range, 0.92-6.27(, with no apparent correlation with either tumor CD44v6 expression, tumor-cell cellularity, or tumor diameter. Tumor-to-nontumor ratios were unfavorable for blood, bone marrow, mammary gland tissue, and skin. CONCLUSIONS: The (186)Re-labeled humanized MAb BIWA 4 can safely be administered to patients with early-stage breast cancer. Tumorto- nontumor ratios were unfavorable, with no apparent correlation with CD44v6 expression, tumor-cell cellularity, or tumor diameter. BIWA 4, therefore, appears to have limitations as a vehicle for radioimmunotherapy in patients with breast cancer.     

ENO1 monoclonal antibody inhibits invasion,proliferation and clone formation of cervical cancer cells

α-enolase (ENO1), highly expressing in cell membranes, cytoplasm and nuclei of cervical cancer and other tumors, acts as a plasminogen receptor and a glycolytic enzyme. ENO1 is found to be associated with tumorigenesis, invasion and migration, and proves to be an ideal target of tumor therapy. In this study, ENO1 monoclonal antibodies (ENO1mAb) was prepared to blockade ENO1 and the therapeutic role was observed in cervical cancer cells. First, ENO1mAb was prepared and screened by evaluating the inhibitory effect on migration and invasion of cervical cancer cells, which is supposed to block ENO1 expressed on cell membrane. Second, folic acid (FA) conjugated PLGA nanoparticles (FA-SS-PLGA) targeting tumor cells were prepared to mediate ENO1mAb entry into cells and its anti-tumor effects were investigated in vitro. We found that PLGA/FA-SS-PLGA nanoparticles-mediated ENO1mAb could antagonize the activity of ENO1 enzyme, significantly decreased the contents of lactic acid and pyruvate, and inhibited the proliferation, migration and clone formation of cervical cancer cells compared with the sham control (P < 0.05). In summary, ENO1mAb could specifically block ENO1 expressed on cell membrane and inhibit ENO1 glycolysis enzyme activity inside tumor cells, and plays a therapeutic role against cervical cancer cells. It suggests that ENO1mAb has promising anti-tumor effects.     

Trastuzumab and interleukin-2 in HER2-positive metastatic breast cancer: a pilot study.

PURPOSE: Trastuzumab as a single agent has activity in metastatic breast cancer; however, the mechanism of action for this clinical activity is uncertain. Whereas interruption of erbB family member signaling occurs, trastuzumab also mediates antibody-dependent cellular cytotoxicity in vitro and in vivo. Based on these data, a clinical trial was performed to test whether interleukin (IL)-2, by increasing FcRgammaIII(+) natural killer (NK) cell numbers and cytolytic function in vivo, when added to trastuzumab, can increase efficacy, be safely given, and avoid the use of chemotherapy. Experimental Design: In this Phase I trial, 10 patients with HER2-overexpressing metastatic breast cancer were treated with IL-2 (1.75 x 10(6) IU/m(2)/day, s.c.) for 7 weeks and trastuzumab (4 mg/kg load and then 2 mg/kg weekly) for 6 weeks. Safety, in vitro immune responses, and clinical responses were assessed. RESULTS: Ten women received a total of 12 cycles of therapy (each cycle lasted 7 weeks). No significant toxicities were seen, and one patient required an IL-2 dose reduction. Among the evaluable patients (10 cycles), the responses were one partial response, five cases of stable disease, and four cases of progressive disease. In vitro immune assays showed NK cell expansion and trastuzumab-mediated increased NK cell killing of breast cancer targets (antibody-dependent cellular cytotoxicity) in a HER2-specific manner but did not correlate with clinical responses. CONCLUSIONS: Trastuzumab + IL-2 is a well-tolerated outpatient regimen that results in NK cell expansion with enhanced in vitro targeted killing of HER2-expressing cells. These preliminary data suggest that this strategy may benefit heavily pretreated metastatic breast cancer patients.     

Insulin-like growth factor-I receptor (IGF-IR) targeting with monoclonal antibody cixutumumab (IMC-A12) inhibits IGF-I action in endometrial cancer cells

Specific insulin-like growth factor-I receptor (IGF-IR) targeting emerged in recent years as a promising therapeutic strategy in cancer. Endometrial cancer is the most common gynaecological cancer in the Western world. The aim of this study was to evaluate the potential of cixutumumab (IMC-A12, ImClone Systems), a fully human monoclonal antibody against the IGF-IR, to inhibit IGF-I-mediated biological actions and cell signalling events in four endometrial carcinoma-derived cell lines (ECC-1, Ishikawa, USPC-1 and USPC-2). Our results demonstrate that cixutumumab was able to block the IGF-I-induced autophosphorylation of the IGF-IR. In addition, the PI3K and MAPK downstream signalling pathways were also inactivated by cixutumumab in part of the cell lines. Prolonged (24 h and 48 h) exposures to cixutumumab reduced IGF-IR expression. Furthermore, confocal microscopy of GFP-tagged receptors shows that cixutumumab treatment led to IGF-IR redistribution from the cell membrane to the cytoplasm. Antiapoptotic effects were evaluated by cleavage of caspase 3 and PARP, and mitogenicity and transformation by proliferation and cell cycle assays. Results obtained showed that cixutumumab abrogated the IGF-I-stimulated increase in proliferation rate, and increased caspase-3 and PARP cleavage, two markers of apoptosis. Of importance, cixutumumab had no effect neither on insulin receptor (IR) expression nor on IGF-I activation of IR. In summary, in a cellular model of endometrial cancer cixutumumab was able to inhibit the IGF-I-induced activation of intracellular cascades, apoptosis and proliferation.     

Specific targeting of a mutant,activated egf receptor found in glioblastoma using a monoclonal antibody

A truncated epidermal growth factor receptor (EGFR) expressed from a rearranged and amplified EGFR gene is present at high frequency in gliomas. In this work we show that when this receptor is expressed in NIH3T3 fibroblasts it is partially activated and confers tumorigenicity to this cell line in vivo but no growth advantage in vitro anchorage-independent growth assays. Because the mutation occurs in the extracellular domain of the receptor, it can be considered to represent a glioma-specific tumour marker. Here we demonstrate that 2 monoclonal antibodies, DH 1.1 and DH8.3, raised to a synthetic peptide spanning the unique junctional sequence, can recognise the mutant receptor but not the normal receptor in both denatured and native states. Furthermore, radiolabelled antibody DH8.3 successfully targets tumours expressing this antigen in nude mice.     

Relationship of monoclonal antibody binding to estrogen and progesterone receptor content in breast cancer

Three monoclonal antibodies--H59, H71, and H72--which react with human breast cancers have been developed using the estrogen-dependent human breast cancer cell line, ZR-75-1, as the immunogen. H59 bound only to estrogen receptor-positive, estrogen-regulated breast cancer cells in culture, whereas H71 and H72 bound breast cancer cells irrespective of the estrogen receptor content. All three antibodies have minimal cross-reactivity with non-breast tissue culture cell lines. The three antigens appear to be glycoproteins located on the cell surface. H59 and H72 antigens bound preferentially to the apical surface of duct cells and may be secreted; H71 antigen demonstrated no evidence of an apical orientation or secretion. The binding of the antibodies to fixed cryosections from 152 breast cancer and 111 benign breast disease specimens has been evaluated using a radioimmunoassay. Eighty-five % of breast cancer and almost 100% of benign disease specimens were bound by at least one antibody. H59 bound 39%, H71 bound 51%, and H72 bound 65% of cancer specimens. Estrogen receptor and progesterone receptor analyses were obtained on 141 specimens. H59 bound almost exclusively to tumor specimens which contained estrogen and/or progesterone receptor, but not to all receptor-positive tumors. Therefore, the H59 antigen appeared to be present on a subset of estrogen receptor-positive tumors. Considering that it bound only to estrogen-regulated cells in culture, the antigen may be estrogen regulated, and its presence may predict a response to hormone therapy. H71 and H72 recognized cell surface differentiation antigens but bound tumor specimens regardless of the receptor content. These antibodies may be useful as independent variables for predicting response to therapy and prognosis of patients with breast cancer.     

Phagocytosis of breast cancer cells mediated by anti-MUC-1 monoclonal antibody, DF3, and its bispecific antibody

Human epithelial mucin, MUC-1, is commonly expressed in adenocarcinoma including 80% of breast cancers. erbB-2 is overexpressed in approximately 30% of breast cancers. Expression of MUC-1 and erbB-2 may be partially overlapping but discoordinate. Therefore, combined use of antibodies directed against these two antigens might increase the number of patients who benefit from immunotherapy. Monoclonal antibody (MAb) DF3 recognizes the MUC-1 tandem repeat. We investigated phagocytosis and cytolysis of cultured human breast cancer cells by monocyte-derived macrophages mediated by MAb DF3 and its bispecific antibody (BsAb) DF3xH22 with the second epitope directed against the Fc component of phagocytic cells. Purified monocytes from healthy donors were cultured with granulocyte macrophage colony-stimulating factor with or without IFN-gamma. antibody-dependent cellular phagocytosis (ADCP) and antibody-dependent cellular cytotoxicity (ADCC) assays were performed with these macrophages and MUC-1-expressing target cells (ZR75-1) in the presence of MAb DF3 and BsAb DF3xH22. ADCP was measured by two-color fluorescence flow cytometry using PKH2 (green fluorescent dye) and R-phytoerythrin (RPE) (red)-conjugated MAb against human CD14 and CD11b and was confirmed by confocal microscopy. ADCC was measured by (51)Cr release assay. Immunohistochemical staining studies of MUC-1 and erbB-2 were performed on 67 primary breast cancer tissues. Expression of MUC-1 and erbB-2 was partially overlapping but discoordinate in 67 consecutive breast cancers. Both MAb DF3 and BsAb DF3xH22 mediated ADCP. However, ADCP mediated by MAb DF3 was greater than that mediated by BsAb DF3xH22. ADCC as detected by (51)Cr release was not seen with either antibody. The addition of IFN-gamma to monocyte-derived macrophage cultures inhibited ADCP compared to granulocyte macrophage colony-stimulating factor alone. Given the partially overlapping but discoordinate expression of MUC-1 and erbB-2 in breast cancer, therapy directed toward both antigens should be considered. MAb DF3 and the BsAb DF3xH22, can effectively mediate phagocytosis of MUC-1-expressing target cells. Further investigations are needed to determine whether this antibody-induced phagocytosis results in long-term specific T-cell activation against MUC-1.