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Background: Targeted therapy options in HER2-negative breast cancer are limited. This open-label, multicenter phase IB dose-escalation trial was conducted to determine safety, tolerability, and antitumor activity of a combination of docetaxel (Taxotere) and increasing doses of adecatumumab, a human IgG1 antibody targeting epithelial cell adhesion molecule (EpCAM), in EpCAM-positive relapsed or primary refractory advanced-stage breast cancer., Patients and Methods: Patients pretreated with up to four prior chemotherapy regimens received increasing adecatumumab doses either every 3 weeks (q3w) or weekly (qw) combined with docetaxel (100 mg/m(2) q3w). Primary end points were safety and tolerability. Antitumor activity was evaluated according to RECIST. Clinical benefit was defined as complete or partial response or stable disease for ≥24 weeks., Results: Thirty-one evaluable patients were treated. Most adverse events were mild to moderate in severity. Neutropenia, leukocytopenia, lymphopenia, and diarrhea (dose-limiting) were the most frequent toxic effects. Maximum tolerated doses of adecatumumab given in combination with docetaxel were 550 mg/m(2) q3w and 360 mg/m(2) qw. Clinical benefit was observed in 44% of patients treated with q3w adecatumumab and docetaxel, increasing to 63% in patients with high EpCAM-expressing tumors., Conclusion: Combination therapy of adecatumumab and docetaxel is safe, feasible, and potentially active in heavily pretreated advanced-stage breast cancer.

Ectodomains of target antigens for antibody-based therapies can be shed from the target cell surface and found in sera of patients. Shed ectodomains of therapeutic targets not only pose the risk of sequestering therapeutic antibodies but, in a multimeric form, of triggering T cell activation by bispecific antibodies binding to CD3 on T cells. Recently, epithelial cell adhesion molecule (EpCAM) has been shown to be activated by release of its ectodomain, called EpEX. Here, we show that only very low amounts of EpEX are detectable in sera of cancer patients. Among 100 cancer patient samples tested, only 17 (17%) showed serum levels of EpEX in excess of 0.05 ng/ml with highest EpEX concentrations of 5.29, 1.37 and 0.52 ng/ml. A recombinant form of human EpEX (recEpEX) was produced to assess its possible effect on redirected lysis and T cell activation by EpCAM/CD3-bispecific BiTE antibody MT110, currently being tested in patients with solid tumor malignancies. RecEpEX had a very minor effect on redirected lysis by MT110 with an approximate IC 50 value of 3,000 ng/ml, which is a concentration close to three orders of magnitude higher than the highest EpEX concentration found in cancer patients. Concentrations of 30 ng/ml EpEX in combination with 250 ng/ml MT110 were minimally required to induce a detectable activation of CD4 (+) and CD8 (+) T cells. We conclude that soluble EpEX in sera of cancer patients is unlikely to pose an issue for the efficacy or safety of MT110, and perhaps other antibodies binding to N-terminal epitopes of EpCAM.

Objective: We evaluated the expression of epithelial cell adhesion molecule (EpCAM) and the potential of MT201 (adecatumumab), a human-monoclonal-antibody that targets EpCAM against chemotherapy-resistant ovarian disease., Study Design: EpCAM expression was evaluated by real-time polymerase chain reaction and flow cytometry. Sensitivity to MT201 antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity was tested in 4-hour chromium-release assays. The effect of interleukin-2 on MT201 ADCC was also studied., Results: High messenger RNA expression by real-time polymerase chain reaction and high EpCAM surface expression by flow cytometry was detected in 71% of ovarian cancers (5 of 7 cell lines). Although these cell lines were highly resistant to complement-dependent cytotoxicity and natural killer-dependent cytotoxicity in vitro (range of killing, 0-7%), EpCAM-positive cell lines showed high sensitivity to MT201 ADCC (range of killing, 27-66%). Incubation with interleukin-2 further increased the cytotoxic activity against EpCAM-positive ovarian cancer cell lines., Conclusion: MT201 may represent a novel, potentially highly effective treatment option for patients with ovarian carcinoma whose body is harboring disease refractory to chemotherapy., (Copyright © 2010 Mosby, Inc. All rights reserved.)

Introduction: Epithelial cell adhesion molecule (EpCAM) is a surface glycoprotein highly differentially expressed in many epithelial malignancies. The goal of this study was to evaluate the expression of EpCAM and the potential of MT201 (adecatumumab), a human monoclonal antibody targeting EpCAM, against multiple primary cervical carcinoma cell lines., Methods: Epithelial cell adhesion molecule expression was evaluated by real-time polymerase chain reaction and flow cytometry in a total of 8 primary cervical cancer cell lines. Sensitivity to MT201-mediated cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity was tested in standard 4-hour 51Cr release assays. To investigate the effect of interleukin-2 (IL-2) on MT201-mediated ADCC, 4-hour 51Cr release assays were also conducted in the presence of low doses of IL-2., Results: High messenger RNA expression by real-time polymerase chain reaction and high EpCAM surface expression by flow cytometry were detected in 4 (50%) of 8 primary cervical carcinoma cell lines. With no exception, the primary cell lines derived from clinically aggressive tumors showed EpCAM overexpression. Whereas these cell lines were highly resistant to complement-dependent cytotoxicity and natural killer (NK)-dependent cytotoxicity in vitro (range of killing, 4%-19%), EpCAM-positive cell lines showed high sensitivity to MT201-mediated ADCC (range of killing, 23%-59%). Incubation with IL-2 in addition to MT201 significantly increased the cytotoxic activity against EpCAM-positive cervical cancer cell lines (P = 0.007). Addition of human serum also further increased the MT201-mediated killing of EpCAM-positive cell lines (P = 0.03)., Conclusions: Epithelial cell adhesion molecule is highly expressed in primary cervical carcinoma cell lines, and these biologically aggressive tumors are highly sensitive to MT201-mediated cytotoxicity in vitro. MT201 may represent a novel, potentially highly effective treatment option for patients with cervical carcinoma, especially for those with advanced, recurrent, or metastatic disease refractory to standard salvage therapy.

With their resistance to genotoxic and anti-proliferative drugs and potential to grow tumors and metastases from very few cells, cancer stem or tumor-initiating cells (TICs) are a severe limitation for the treatment of cancer by conventional therapies. Here, we explored whether human T cells that are redirected via an EpCAM/CD3-bispecific antibody called MT110 can lyse colorectal TICs and prevent tumor growth from TICs. MT110 recognizes EpCAM, a cell adhesion molecule expressed on TICs from diverse human carcinoma, which was recently shown to promote tumor growth through engagement of elements of the wnt pathway. MT110 was highly potent in mediating complete redirected lysis of KRAS-, PI3 kinase- and BRAF-mutated colorectal TICs, as demonstrated in a soft agar assay. In immunodeficient mice, MT110 prevented growth of tumors from a 5,000-fold excess of a minimally tumorigenic TIC dose. T cells engaged by MT110 may provide a potent therapeutic means to eradicate TICs and bulk tumor cells derived thereof.

Background: High-level expression of epithelial cell adhesion molecule (EpCAM) is associated with unfavorable prognosis in breast cancer. This study was designed to investigate two doses of the fully human IgG1 anti-EpCAM antibody adecatumumab (MT201) in patients with metastatic breast cancer (MBC)., Methods: A total of 109 patients were stratified into high- and low-level EpCAM expression by immunohistochemical staining of primary tumors and subsequently randomly assigned to receive monotherapy with either high- (6 mg/kg every two weeks (q2w)) or low-dose adecatumumab (2 mg/kg/ q2w) until disease progression., Results: No complete or partial tumor responses could be confirmed by central RECIST assessment. The probability for tumor progression was significantly lower in patients receiving high-dose adecatumumab and expressing high levels of EpCAM (hazard ratio 0.43; P = 0.0057 versus low dose and low EpCAM). Three of 18 patients with highest EpCAM expression treated with adecatumumab developed new metastases up to week 6, compared with 14 of 29 patients with low EpCAM. Most frequent treatment-related adverse events (high dose/low dose) were chills (59%/20%), nausea (55%/18%), fatigue (39%/23%) and diarrhea (43%/7%)., Conclusions: Single-agent adecatumumab shows dose- and target-dependent clinical activity in EpCAM-positive MBC, albeit no objective tumor regression. Further investigation of adecatumumab in patients with EpCAM-overexpressing tumors and lower tumor burden is warranted.

Background: Rising serum levels of prostate-specific antigen (PSA) after radical prostatectomy are indicative of recurrent prostate cancer. This double-blind, placebo-controlled phase II study evaluated the anti-tumour activity of the anti-epithelial cell adhesion molecule (EpCAM) antibody adecatumumab in delaying biochemical disease progression., Patients and Methods: Prostate cancer patients with increasing serum PSA levels following radical prostatectomy were randomized to low- (2 mg/kg) or high-dose adecatumumab (6 mg/kg) or placebo. The primary efficacy endpoint was the mean change from baseline in total serum PSA at week 24. Secondary endpoints included PSA response rate, prolongation of serum PSA doubling time and time to biochemical disease progression., Results: The primary and secondary endpoints of the study were not met in the predefined analyses. In a retrospective analysis of patients with baseline PSA ≤ 1 ng/ml and a high EpCAM expression, both the mean increase in PSA from baseline to week 24 and the PSA doubling time at week 15 were significantly improved in the high-dose adecatumumab group compared with the placebo group. Most frequent treatment-related clinical adverse events were gastrointestinal (diarrhoea and nausea) or general events (chills), showing a dose dependency but no grade 3/4 intensity in any patient., Conclusion: In men with rising PSA levels after radical prostatectomy and no evidence of clinical relapse, adecatumumab delayed disease progression in a subgroup of patients with baseline PSA levels ≤ 1 ng/ml and high EpCAM-expressing tumours., (Copyright © 2010 S. Karger AG, Basel.)

We evaluated the expression of epithelial cell adhesion molecule (EpCAM) and the potential of MT201 (adecatumumab), a human monoclonal antibody against EpCAM, in uterine serous papillary carcinoma (USPC). EpCAM expression was evaluated by real-time PCR and immunohistochemistry in a total of 56 USPC fresh-frozen biopsies and paraffin-embedded tissues. EpCAM surface expression was also evaluated by flow cytometry and immunohistochemistry in six USPC cell lines. Sensitivity to MT201 antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity was tested against a panel of primary USPC cell lines expressing different levels of EpCAM in standard 5-h (51)Cr release assays. EpCAM transcript was significantly overexpressed in fresh-frozen USPC when compared with normal endometrial cells (NEC). Median (minimum-maximum) copy number was 943.8 (31.5-1568.3) in tumor samples versus 12.9 (1.0-37.0) in NEC (P < 0.001). By immunohistochemistry, EpCAM expression was found in 96% (26 out of 27) of USPC samples with significantly higher expression compared with NECs (P < 0.001). High surface expression of EpCAM was found in 83% (five out of six) of the USPC cell lines tested by flow cytometry. EpCAM-positive cell lines were found highly sensitive to MT201-mediated antibody-dependent cellular cytotoxicity in vitro, whereas primary USPC cell lines were resistant to natural killer cell-dependent cytotoxicity. Human plasma IgG did not significantly inhibit MT201-mediated cytotoxicity against USPC. EpCAM is highly expressed in uterine serous carcinoma at mRNA and protein levels, and primary USPC are highly sensitivity to MT201-mediated cytotoxicity. MT201 might represent a novel therapeutic strategy in patients harboring advanced/recurrent or metastatic USPC refractory to standard treatment modalities.