A phase I trial of the trifunctional anti Her2 × anti CD3 antibody ertumaxomab in patients with advanced solid tumors

Background

Ertumaxomab (ertu) is a bispecific, trifunctional antibody targeting Her2/neu, CD3 and the Fcγ-receptors I, IIa, and III forming a tri-cell complex between tumor cell, T cell and accessory cells.

Methods

Patients (pts) with Her2/neu (1+/SISH positive, 2+ and 3+) expressing tumors progressing after standard therapy were treated to investigate safety, tolerability and preliminary efficacy. In this study, ertu was applied i.v. in 2 cycles following a predefined dose escalating scheme. Each cycle consisted of five ascending doses (10–500 μg) applied weekly within 28 days with a 21 day treatment-free interval. If 2 pts experienced a dose limiting toxicity (DLT) at a given dose level, the maximum tolerated dose (MTD) had been exceeded.

Results

Fourteen heavily pretreated pts (e.g. breast, rectal, gastric cancer) were enrolled in the four main cohorts. Three (21 %) pts had to be replaced. Two serious adverse events (SAE) with possible relation to the investigational drug were seen, both fully reversible. A DLT was not detected. Consequently, the MTD could not be determined. All adverse events (AE) were transient and completely reversible. Most frequent AEs were fatigue (14/14), pain (13/14), cephalgia (12/14), chills (11/14), nausea (8/14), fever (7/14), emesis (7/14) and diarrhea (5/14). Single doses up to 300 μg were well tolerated (total dose up to 800 μg per cycle). We observed one partial remission and two disease stabilizations after first treatment cycle.

Conclusions

Single doses up to 300 μg could be safely administered in an escalating dose scheme. Immunological responses and clinical activity warrant further evaluation in patients with Her2 over expressing tumors.

Trial registration

EudraCT number: 2011-003201-14; ClinicalTrials.gov identifier: NCT01569412

Long-Term Treatment of HIV-Infected MT-4 Cells in Culture with HIV Proteinase Inhibitor RO 31-8959 Leads to Complete Cure of Infection

An HIV-infected cell culture was treated with the specific HIV proteinase inhibitor Ro 31-8959 for three months to analyse the antiviral effect and possible cytotoxicity of the drug in long-term treatment. The drug was added 1 h after HIV infection with 0.002 m.o.i. and maintained for 87 days in the cell culture. There was no detectable cell death nor any evidence of HIV production in this time. Cells were proven to be initially infected, since premature drug removal led to a re-emergence of infectious HIV and cell death. However, after 87 days of treatment the drug could be removed safely and HIV was cleared demonstrably from the culture. These data suggest that long-term dosage may be advantageous to the clinical treatment of HIV infection by HIV proteinase inhibitors.

Elimination of cancer stem cells (CD133+/EpCAM+) from malignant ascites by the trifunctional antibody catumaxomab: Results from a pivotal phase II/III study

3014

Background: Putative cancer stems cells (CSCs) are defined as “tumor-initiating cells” that have the capacity to self-renew and to give rise to the variety of differentiated cells found in the malignancy. The CD133 membrane glycoprotein represents a CSC marker that has been previously demonstrated to be capable of identifying a cancer-initiating subpopulation in brain tumors, melanoma, and EpCAM+ solid tumors. The trifunctional anti-EpCAM x anti-CD3 antibody catumaxomab efficiently eliminates tumor cells from the peritoneal fluid of malignant ascites (MA) patients as demonstrated in a pivotal phase II/III trial (Parsons et al., ASCO 2008). Here we report on the presence of CD133+/EpCAM+ putative CSCs in MA and, more importantly, on the elimination of this cell population from the peritoneal fluid of MA patients by means of catumaxomab therapy. Methods: 18 CTX-refractory patients with MA caused by a variety of primary carcinoma diseases (i.e., ovarian, pancreas, and gastric cancer) were analyzed for the presence CD133+/EpCAM+ cells in peritoneal fluids by means of CD133+/EpCAM+ double staining on cytospin preparations. Analyses were performed before, 2 days after the first, and 1 day after the last catumaxomab infusion, respectively. Double-stained cytospin preparations were evaluated with a computerized image analysis system. Results: Before therapeutic intervention, CD133+/EpCAM+ cells were detected in the peritoneal fluids of 14 from 18 patients suffering from MA. After the 1st infusion of catumaxomab (10μg), 9 of these 14 patients showed complete elimination of the CD133+/EpCAM+ cells. After 4 i.p. catumaxomab infusions (10μg day 0, 20μg day 3, 50μg day 7 and 150μg day 10) the CD133+/EpCAM+ cells were completely eliminated from the peritoneal fluids of all 14 MA patients. Conclusions: In a preliminary monitoring study, putative CSCs (CD133+/EpCAM+) were present in peritoneal fluids of 78 % of analyzed MA patients with different underlying primary tumor entities. Catumaxomab efficiently destroyed CD133+/EpCAM+ cells within peritoneal fluids of MA patients. Consequently, catumaxomab-based therapeutic measures may offer an additional treatment opportunity to eliminate CSCs in EpCAM+ malignancies.

[Table: see text]

Decrease of VEGF within malignant ascites during catumaxomab treatment: Results from a pivotal phase II/III study

3029

Background: Treatment with the trifunctional anti-EpCAM x anti-CD3 antibody catumaxomab efficiently eliminates tumor cells from the peritoneal cavity (Jäger et al., ASCO 2007) and led to clinically relevant prolongation of puncture-free survival (PuFS) in patients with malignant ascites (MA) in a pivotal phase II/III trial (Parsons et al., ASCO 2008). As vascular endothelial growth factor (VEGF) levels are markedly elevated in MA in comparison to cirrhotic ascites the question was addressed whether catumaxomab treatment impacts the expression or accumulation of VEGF within MA. Here we report that in addition to tumor cell depletion, VEGF protein levels in MA significantly decreased upon catumaxomab therapy. We propose that the strongly correlated tumor cell elimination and reduced VEGF protein levels are causative for the prolonged PuFS of patients suffering from MA. Methods: VEGF and total protein levels were measured by ELISA and BCA from MA supernatants before catumaxomab therapy, after the 1st infusion (10μg; day 3) and after the 4th infusion (150μg; day 11). Data were statistically analysed for the ratio of the VEGF protein concentration versus the total protein concentration for the MA treatment groups with ovarian (OC) or nonovarian cancer (NC) as underlying disease and the corresponding control groups that received paracentesis only. Results: One day after the last catumaxomab infusion 46 or 47 patients analysed in the OC or NC treatment group showed a statistically significant decrease in VEGF to total protein ratio when compared to the measurement before catumaxomab therapy (ANOVA p=0.034 for OC and p<0.001 for NC). These results are consistent with the tumor cell elimination previously assessed in these patients. In contrast, the OC control group showed a statistically significant increase of VEGF to total protein ratio (p=0.009), which is accompanied by an increase in tumor cell numbers. In the NC control group VEGF to total protein ratio remained unaffected (p=0.096). Conclusions: Catumaxomab therapy significantly reduced VEGF protein levels correlating with tumor cell elimination in MA, which in turn led to the prevention of fluid accumulation in the peritoneal cavity and finally to prolonged PuFS of patients suffering from MA.

[Table: see text]

Clinical benefit of catumaxomab in malignant ascites in patient subpopulations in a pivotal phase II/III trial

e14000

Background: Parsons et al. (ASCO 2008) reported the results of a pivotal phase II/III trial in patients with malignant ascites due to epithelial cancer. Treatment with the trifunctional antibody catumaxomab resulted in a clinically relevant prolongation of puncture-free survival, defined as the time to the next therapeutic puncture or the time to death, whichever occurred first. Malignant ascites is a typical late-stage manifestation of cancer associated with a poor prognosis and survival. Effective treatment options are limited. It is thus of special interest if all patient subgroups derive objective benefit from treatment. Methods: A post-hoc analysis was performed on the 258 patients with epithelial tumors treated with catumaxomab + paracentesis or paracentesis alone (control) in the pivotal trial to investigate any association between the primary endpoint (puncture-free survival) and the primary tumor, metastases, or other prognostic parameters. Results: Puncture-free survival was lower in patients with non-ovarian vs ovarian tumors and those with a poor prognosis (metastases vs no metastases, elderly vs younger, or low vs serum protein level). However, there was always a statistically significant treatment effect for catumaxomab compared with the respective control group (p≤0.0001, log rank test, for all comparisons) (see table). Conclusion: Catumaxomab demonstrated a significant clinical benefit in patients with malignant ascites independent of the primary tumor or other prognostic factors. Therefore, catumaxomab could be considered as a treatment option for patients with a poor prognosis.

[Table: see text]

[Table: see text]

Safety of catumaxomab: Cytokine-release-related symptoms as a possible predictive factor for efficacy in a pivotal phase II/III trial in malignant ascites

3036

Background: As a targeted immunotherapy, the trifunctional antibody catumaxomab specifically binds to epithelial cell-adhesion molecule (EpCAM) on tumor cells and attracts T-cells via CD3 and accessory cells via its FcγRI/III+ region. The clinical relevance of this mode of action was demonstrated by Parsons et al. (ASCO 2008) in a pivotal phase II/III trial. Catumaxomab treatment resulted in a clinically relevant prolongation of puncture-free survival (defined as time to next puncture or time to death, which ever occurred first) in patients with malignant ascites. One of the most common adverse events associated with catumaxomab is cytokine-release-related-symptoms (CRRSs), which might be of predictive value for efficacy. Methods: The safety profile of catumaxomab was identified in the pivotal study. CRRSs (pyrexia, nausea, and vomiting) were among the most common adverse events in the catumaxomab group. A correlation between CRRSs and puncture-free survival, the primary endpoint, was performed to investigate whether patients who had CRRSs benefited from catumaxomab treatment more than those who had no CRRSs. Results: Among 157 patients, CRRSs were limited to the duration of catumaxomab treatment, with a median onset of 1 day after catumaxomab administration and a median duration of 1–2 days. Most of these symptoms were mild to moderate and were manageable by standard symptomatic treatment. Only 6 of 101 patients with CRRSs who were treated with concomitant medication required systemic corticoid therapy. Puncture-free survival was longer (48 days) in patients with (81%) CRRSs during catumaxomab treatment than in patients without (19%) CRRSs (27 days), although the difference was not statistically significant (p=0.1546, log rank test). Conclusions: CRRSs are a common occurrence with catumaxomab, due to its mode of action, during the treatment of patients with malignant ascites. Since CRRSs appear to be correlated with efficacy, they may therefore be a predictive factor for catumaxomab efficacy.

[Table: see text]

Peritoneal carcinomatosis immunotherapy with the trifunctional anti-EpCAM x anti-CD3 antibody catumaxomab in patients with colon, gastric, or pancreatic cancer: Long-term results after a 2-year follow-up

3033

Background: Peritoneal carcinomatosis (PC) from gastrointestinal (GI) cancer is associated with a poor outcome. The trifunctional antibody catumaxomab may induce remission by redirecting T-lymphocytes and Fcγ-receptor I/III positive accessory cells to tumor cells. The aim of this study was to investigate the treatment of PC with intraperitoneal catumaxomab. Methods: Patients with epithelial cell adhesion molecule (EpCAM)-positive PC from GI cancer were enrolled in a multicenter phase I study and received four sequential intraperitoneal catumaxomab infusions on days 0, 3, 7, and 10 at increasing doses. Results: Twenty-four patients were enrolled. The maximum tolerated dose (MTD) was reached at 10, 20, 50, and 200 μg on days 0, 3, 7, and 10, respectively. The most common drug-related adverse events at the MTD were fever, vomiting, abdominal pain, skin toxicity, and nausea. Eleven of 17 evaluable patients (65%) were progression-free at final examination: one patient had a complete response and three patients had a partial response. EpCAM-positive cells in peritoneal lavage samples decreased in six of 10 evaluable patients. Patient survival was compared in a post hoc matched-pair analysis with PC patients treated with conventional intravenous chemotherapy. Median survival from the time of diagnosis of PC was 502 days in study patients versus 180 days in control patients (log-rank p = .0083). Conclusions: Intraperitoneal treatment with catumaxomab had an acceptable safety profile. Elimination of tumor cells from peritoneal lavage samples, delayed disease progression, and prolonged survival indicate that intraperitoneal catumaxomab is a promising option for the treatment of PC from GI cancer.

[Table: see text]

Influence of catumaxomab on tumor cells in bone marrow and blood in ovarian cancer

The trifunctional antibody catumaxomab with bispecificity for the epithelial cell adhesion molecule EpCAM and the T-cell antigen CD3, is a new therapeutic strategy for ovarian cancer patients with symptomatic malignant ascites. Whether or not intraperitoneal (i.p.) catumaxomab-therapy has influence on disseminated and circulating tumor cells was investigated by analyzing cytokeratin-positive (CK+) cells in bone marrow (BM) and peripheral blood (PB). Fourteen ovarian cancer patients with symptomatic ascites were treated with catumaxomab (up to 5 i.p.-infusions; increasing dosages (10-200 microg)). CK+-cells were isolated before and after antibody-therapy by density gradient centrifugation and immunocytochemistry (anti-CK antibody A45-B/B3). Catumaxomab-treatment resulted in the sustained reduction of ascites flow and arrested ascites reaccumulation. The mean overall survival was 8 months. CK+-cells in the BM were found in 70% before and 83% after therapy (in the PB 57% and 42%, respectively). A marked reduction of CK+-cells occurred in the BM in 2 and in the PB in 4 patients. Catumaxomab shows a strong intraperitoneal effect and possibly also systemic effects on tumor cells in the BM and PB.

Characterisation of the new EpCAM-specific antibody HO-3: implications for trifunctional antibody immunotherapy of cancer

Epithelial cell adhesion molecule EpCAM is a transmembrane glycoprotein that is frequently overexpressed in a variety of carcinomas. This pan-carcinoma antigen has served as the target for a plethora of immunotherapies. Innovative therapeutic approaches include the use of trifunctional antibodies (trAbs) that recruit and activate different types of immune effector cells at the tumour site. The trAb catumaxomab has dual specificity for EpCAM and CD3. In patients with malignant ascites, catumaxomab significantly increased the paracentesis-free interval, corroborating the high efficacy of this therapeutic antibody. Here, we characterised the monoclonal antibody (mAb) HO-3, that is, the EpCAM-binding arm of catumaxomab. Peptide mapping indicated that HO-3 recognises a discontinuous epitope, having three binding sites in the extracellular region of EpCAM. Studies with glycosylation-deficient mutants showed that mAb HO-3 recognised EpCAM independently of its glycosylation status. High-affinity binding was not only detected for mAb HO-3, but also for the monovalent EpCAM-binding arm of catumaxomab with an excellent K_D of 5.6 × 10⁻¹⁰ M. Furthermore, trAb catumaxomab was at least a 1000-fold more effective in eliciting the eradication of tumour cells by effector peripheral blood mononuclear cells compared with mAb HO-3. These findings suggest the great therapeutic potential of trAbs and clearly speak in favour of EpCAM-directed cancer immunotherapies.

Immunomonitoring results of a pivotal phase II/III study with the trifunctional antibody catumaxomab (anti-EpCAM x anti-CD3) in ovarian cancer patients with malignant ascites

3020

Background: Malignant ascites is a symptom of late-stage tumor disease and associated with a poor prognosis. The trifunctional antibody catumaxomab specifically binds to EpCAM+ tumor cells and redirects CD3+ T lymphocytes and FcγR I/III+ accessory cells simultaneously to the tumor site. Methods: 129 (85 catumaxomab; 44 control paracentesis) EpCAM-positive ovarian cancer patients with symptomatic malignant ascites were compared in an open-label, multicenter, randomized study for efficacy and tolerability of intraperitoneally given catumaxomab. Various in vivo and in vitro immunological and pharmacodynamic parameters were measured directly from ascites cell preparations. Results: During the course of catumaxomab treatment in the ascites fluid tumor cells dramatically decreased and leukocytes increased. Accordingly, the in vivo effector/target ratio (CD45+/EpCAM+) showed an drastic increase from a baseline of 6:1 to 10,000:1 already after the first infusion (all median). Leukocyte expansion was accompanied by in vivo upregulation of T cell activation marker CD69 on CD4+ and CD8+ T cells in the ascites fluid and an increase of IL-6 in serum at 24 hours after each infusion indicating systemic effects of catumaxomab. In vitro pharmacodynamic studies were carried out with screening samples to further validate the in vivo results. Similarly, the in vitro experiments showed efficient EpCAM+ tumor cell elimination, leukocyte expansion, drastical improvement of the effector/target ratio and activation of T cells. Additionally, a strong upregulation of activating cytokines IL-2 and IFN-γ (TH1 cytokine profile) and proliferation of CD4+, CD8+ T cells and CD11c+ accessory cells were demonstrated in the samples with catumaxomab compared to controls. Conclusions: Intraperitoneal catumaxomab treatment triggers activation and proliferation of different immune cells and leads to elimination of tumor cells within malignant ascites. These data confirm the postulated mode of action of trifunctional catumaxomab in vivo and correlate with clinical efficacy in patients with malignant ascites.

[Table: see text]

Effects of the trifunctional antibody catumaxomab (anti-EpCAM x anti-CD3) on proliferation and cytokine secretion of immune cells in malignant pleural effusion

3046

Background: The trifunctional antibody catumaxomab specifically binds EpCAM+ tumor cells, CD3+ T lymphocytes and accessory cells via FcγR I/III. Thus the antibody induces tumor specific cell mediated cytotoxicity in vitro and in vivo. Following last years’ ASCO presentation on a phase I/II trial showing safety and efficacy of repetitive intrapleural administration of catumaxomab in patients with EpCAM positive, malignant pleural effusion (MPE), we now present data on the responsiveness of immune cells from pleural fluid to catumaxomab. Methods: Pleural fluid of patients with EpCAM-positive MPE treated with i.pl. catumaxomab was collected before treatment. Cells were harvested from the fluid and cultured ± 100 ng/ml catumaxomab using an in vitro proliferation assay. After 72 h of culture, proliferation of T cells (CD4+ and CD8+) and monocytes (CD11c+) was determined. In addition, cell supernatants after 24h incubation ± catumaxomab were analysed for their TH1/TH2 cytokine profile (IL-2, IL-4, IL-6, IL-10, IFN-γ and TNF- a). Results: Incubation in presence of catumaxomab led to a pronounced increase of CD4+ CD8+ and CD11+ cell numbers indicating a proliferation of these cells, whereas cultures without catumaxomab showed no proliferation of immune cells. Analysis of supernatants after 24 h revealed levels of IL-2, IL-6, IFN-γ and TNF-a, from cells incubated with catumaxomab that were distinctly higher than in cultures without catumaxomab. Conclusions: The immunologic nature of catumaxomab-induced responses in patients with pleural effusion accompanied by a reduction of tumor cells, could be underlined impressively with in vitro data obtained from pleural cells showing catumaxomab-induced proliferation of T cells and accessory cells and TH1-directed cytokine secretion. The data are equivalent to results observed in the peritoneal fluid of ascites patients.

[Table: see text]

EpCAM an immunotherapeutic target for gastrointestinal malignancy: current experience and future challenges

Despite advances in surgery and adjuvant regimes, gastrointestinal malignancy remains a major cause of neoplastic mortality. Immunotherapy is an emerging and now successful treatment modality for numerous cancers that relies on the manipulation of the immune system and its effector functions to eradicate tumour cells. The discovery that the pan-epithelial homotypic cell adhesion molecule EpCAM is differentially expressed on gastrointestinal tumours has made this a viable target for immunotherapy. Clinical trials using naked anti EpCAM antibody, immunoconjugates, anti-idiotypic and dendritic cell vaccines have met variable success. The murine IgG2a Edrecolomab was shown to reduce mortality and morbidity at a level slightly lower than treatment with 5FU and Levamisole when administered to patients with advanced colorectal carcinoma in a large randomised controlled trial. Fully human and trifunctional antibodies that specifically recruit CD3-positive lymphocytes are now being tested clinically in the treatment of minimal residual disease and ascites. Although clinical trials are in their infancy, the future may bring forth an EpCAM mediated approach for the effective activation and harnessing of the immune system to destroy a pathological aberrance that has otherwise largely escaped its attention.

Increased chondroitin sulphate proteoglycan expression (B5 immunoreactivity) in metastases of uveal melanoma

BACKGROUND

Metastatic uveal melanoma has a poor prognosis and limited therapeutic options. Proteoglycans are involved in tumor cell invasion and metastatic behavior. The mAbB5 stains a chondroitin sulphate proteoglycan (CSPG) on cutaneous melanoma cells. Here, we compare the B5-staining of CSPG in primaries and metastases of uveal melanoma.

MATERIAL AND METHODS

Immunohistopathological staining was performed in 15 cutaneous and 39 uveal melanoma samples. A score for intracellular and surface staining was established. B5 staining was compared in primaries and metastases of uveal melanoma using Student's t-test.

RESULTS

Eight of 11 (73%) uveal melanoma metastases were positive for B5-staining whereas only 5 of 28 (18%) primary uveal melanoma samples were B5-positive (P < 0.001). Nine of 15 cutaneous melanoma samples (60%) were B5-positive without significant difference between primary and metastatic lesions. Surface staining was found both on uveal melanoma metastases and cutaneous melanomas.

CONCLUSIONS

CSPG was expressed significantly more often in metastases than in primaries of uveal melanoma. It potentially may be one factor associated with metastatic spread. Further studies are needed to determine its use as prognostic factor. The mAbB5 may also be a promising tool for immunotherapy due to its strong staining of CSPG on the surface of cutaneous and metastatic uveal melanoma cells.

Treatment of non-small cell lung cancer (NSCLC) patients with the trifunctional antibody catumaxomab (anti-EpCAM x anti-CD3): Results of a phase I/II study

2540

Background: Catumaxomab is a trifunctional monoclonal antibody with binding specificities to human EpCAM, human CD3 and Fc gamma receptor I/III-positive accessory cells leading to induction of cell mediated, tumor specific cytotoxicity. As EpCAM is overexpressed in NSCLC patients (pts.) the present study was conducted in order to evaluate safety and tolerability of intravenous (i.v.) treatment with catumaxomab. Methods: Patients with NSCLC (UICC stage IB - IV) with at least one prior therapy were included into this trial. Escalating doses of 2–7,5 μg catumaxomab were given as a single i.v. infusion. Various doses of dexamethasone premedication (10 and 40 mg) were investigated at five different dose levels (level: catumaxomab (μg)/dexamethasone (mg)/number of pts. treated: I: 2/40/3, II: 2/0/1, III: 5/40/4, IV: 5/10/5, V: 7,5/40/2, respectively). Primary objectives were toxicity and definition of the maximum tolerated dose (MTD). In addition, time to progression (TTP) and survival were evaluated. Results: 24 pts. were included into this trial; 15 pts. were evaluable for safety analysis, 13 pts. for follow up. 13/15 pts. experienced a total of 68 AEs, of which 55 were reported as drug related and 9 defined as critical AEs. The majority (77%) of AEs were mild (CTC grade 1 and 2), 19% were grade 3 and 4% grade 4. 73% of the AEs were elevation of liver enzymes (gamma-GT, AST and ALT). Other toxicities were increase of blood ALP, dizziness, lymphopenia and pyrexia. Dose limiting toxicity (DLT) was a transient grade 3 and 4 elevation of ALT, AST and gamma-GT, observed at dose levels IV and V. Maximum tolerated dose (MTD) was defined at dose level III. Remarkably, follow up data showed 4/4 pts. stage IIIB and 1/4 pts. stage IV still alive at 26–28 months after catumaxomab treatment. Conclusion: 5 μg of catumaxomab can safely be administered intravenously with 40 mg dexamethasone as premedication. Based on the current results we recommend this regimen as first dose in a future study consisting of multiple catumaxomab infusions in pts. with locally advanced NSCLC.

[Table: see text]

Efficacy of intraperitoneal treatment with the trifunctional antibody catumaxomab in patients with GI-tract cancer and peritoneal carcinomatosis: A matched-pair analysis

2544

Background: Peritoneal carcinomatosis (PC) due to GI-tract cancer is an advanced tumor stage with poor survival. At present, no standard therapy has been recommended, as chemotherapy and surgery showed only limited efficacy in affected patients. When applied intraperitoneally (i.p.), the trifunctional antibody catumaxomab could be shown to destroy intraperitoneal tumor cells in patients with malignant ascites due to ovarian cancer. While binding simultaneously to EpCAM (on tumor cells), CD3 (T cells) and, via the Fc region, to Fc gamma receptor 1 and 3 on accessory cells, it induces a complex immunoreaction against epithelial tumor cells. The aim of this study was to investigate clinical efficacy of i.p. catumaxomab therapy in patients with PC compared to a matched control group. Methods: Between 2003 and 2005, 22 patients with PC due to cancer of colon (n=10), stomach (8), pancreas (3) and CUP (1) received treatment with catumaxomab within a phase I study. Treatment consisted of 3 to 4 i.p. applications (10–200 μg) of escalating catumaxomab doses. The survival was compared with patients receiving conventional therapies in a matched-pair analysis regarding sex, age, tumor surgery, chemotherapy, and extent of PC. Patients with existing ileus and clinically significant ascites were not included. Results: Follow up of patients receiving catumaxomab showed a median survival of 12.2 months (range 2–34) after first diagnosis of peritoneal carcinomatosis vs. 9.7 months (range 1–40) in patients with conventional treatment (p=0.005; log-rank). These data will be updated at presentation. Conclusion: Intraperitoneal treatment with the trifunctional antibody catumaxomab may be an attractive option for treatment of patients with peritoneal carcinomatosis due to GI-tract cancer. The convincing results have to be further investigated in clinical phase II/III trials.

[Table: see text]

Lasting remission following multimodal treatment in a patient with metastatic breast cancer

We report on a lasting remission from multimodal treatment in a patient with hepatic metastasized breast cancer. After surgical removal of a singular hepatic metastasis, the patient underwent leukapheresis of peripheral blood mononuclear cell (PBMCs). For induction chemotherapy, the patient received 2 cycles of epirubicin and paclitaxel (ET). After 1 cycle of epirubicin and ifosfamide (EI), peripheral blood stem cells were harvested. After a final cycle of ET, the patient underwent high-dose chemotherapy (HDCT; thiotepa 600 mg/m/melphalan 180 mg/m) and autologous stem cell transplantation. Once reconstitution was achieved, PBMCs were reinfused followed by i.v. application of a trifunctional antibody (TrAb) with specificities anti-EpCAMxanti-CD3. TrAbs are able to simultaneously bind tumor cells, T cells, and additionally FcgammaR type I and III+accessory cells via their Fc region. Side-effects during treatment were hematotoxicity, mucositis and gastrointestinal toxicity. TrAb treatment resulted in intermittent fever, chills, elevated liver enzymes, systemic inflammatory response syndrome and pulmonary leakage. With a follow-up period of more than 8 years the patient is still in remission (96+months). This case suggests the feasibility and efficacy of combining surgery, standard and HDCT, and subsequent immunotherapy in metastatic breast cancer. Further investigation of this approach is indicated in a subgroup of patients with oligometastatic breast cancer.

Combined treatment of metastatic breast cancer (MBC) by high-dose chemotherapy (HDCT) and bispecific antibodies: a pilot study

This pilot study analyzed the efficacy and toxicity of high-dose chemotherapy (HDCT), autologous stem-cell transplantation (ASCT) and subsequent immunotherapy with T-cell reinfusion and trifunctional antibodies (trAbs) in chemotherapy-sensitive patients with metastatic breast cancer (MBC).

PATIENTS AND METHODS

After leukapheresis and cryopreservation of T-cells, patients received 2 cycles of induction chemotherapy ET (epirubicin/paclitaxel) and 1 cycle of El (epirubicin/ifosfamide), followed by G-CSF and stem-cell harvest. After a final cycle of ET, responders (CR/PR) underwent HDCT (thiotepa 600 mg/m2/melphalan 140-180 mg/m2) and ASCT. Once reconstitution was achieved, T-cells were reinfused, followed by application of trifunctional antibodies with specificities anti-EpCAM X anti-CD3 and anti-Her2/neu X anti-CD3.

RESULTS

Thirty-three patients were recruited into the study and 19, who had responded to initial chemotherapy, underwent HDCT and ASCT (4 CR, 15 PR, OR = 57.6%; 95% CI: 40-75%). Two early deaths were observed (1 toxic, 1 early progression). T-cell reinfusion and trAbs were given to 17 patients. TrAbs treatment resulted in intermittent fever, chills and elevated liver enzymes, which were seen in all patients. The median overall survival was 27.7 months (range: 5.9-82.6+). Patients who received 3 trAbs doses showed a trend towards an improved overall survival (47.2 vs. 22.4 months, p = 0.08 log rank).

CONCLUSION

This pilot study has shown the feasibility of combining HDCT with immunotherapy in MBC. Further investigation of this approach is indicated.

Opsonization with a trifunctional bispecific (alphaCD3 x alphaEpCAM) antibody results in efficient lysis in vitro and in vivo of EpCAM positive tumor cells by cytotoxic T lymphocytes

Removab is a trifunctional bispecific antibody which can bridge CD3+ T cells and epithelial cell adhesion molecule positive (EpCAM+) tumor cells, and binds with its Fc fragment to antigen presenting cells. To explore a new approach for the treatment of patients with carcinoma of the upper aerodigestive tract, we investigated whether Removab can induce specific cellular responses to the EpCAM+ carcinoma cell line BHY. Particular emphasis was put on the opsonization of peripheral blood mononuclear cells (PBMN) with respect to clinical application. Tumor cells and allogeneic PBMN of healthy volunteers were incubated with or without Removab. In a third group, PBMN were opsonized with Removab and washed before incubation with tumor cells. Inverse microscopy, ELISPOT, flow cytometry analysis and cytotoxicity assays on the chorioallantois membrane (CAM) were performed. In comparison with PBMN alone, opsonization with Removab resulted in: a) activation of CD83+ antigen presenting cells, b) secretion of interferon gamma, and c) granzyme B mediated lysis of targeted BHY cells by EpCAM specific CD8+ T cells. The secretion of tumor necrosis factor alpha, interferon gamma and interleukin-2 by opsonized PBMN was significantly reduced after 24 h. Washed opsonized PBMN maintained their lytic activity against tumor cells as tested on the CAM. Removab is an appropriate agent for the therapeutic amplification of T cell responses against EpCAM+ tumor cells by opsonization of PBMN without putting patients at risk for severe adverse events caused by a cytokine storm.

Induction of a long-lasting antitumor immunity by a trifunctional bispecific antibody

Bispecific antibodies (bsAbs) can efficiently mediate tumor cell killing by redirecting preactivated or costimulated T cells to disseminated tumor cells, especially in a minimal residual disease situation. This study demonstrates that the trifunctional bsAb BiLu is able to kill tumor cells very efficiently without any additional costimulation of effector cells in vitro and in vivo. Remarkably, this bsAb also induces a long-lasting protective immunity against the targeted syngeneic mouse tumors (B16 melanoma and A20 B-cell lymphoma, respectively). A strong correlation was observed between the induction of a humoral immune response with tumor-reactive antibodies and the survival of mice. This humoral response was at least in part tumor specific as shown in the A20 model by the detection of induced anti-idiotype antibodies. Both the survival of mice and antitumor titers were significantly diminished when F(ab')(2) fragments of the same bsAb were applied, demonstrating the importance of the Fc region in this process. With the use of T-cell depletion, a contribution of a cellular antitumor response could be demonstrated. These results reveal the necessity of the Fc region of the bsAb with its potent immunoglobulin subclass combination mouse immunoglobulin G2a (IgG2a) and rat IgG2b. The antigen-presenting system seems to be crucial for achieving an efficient tumor cell killing and induction of long-lasting antitumor immunity. Hereby, the recruitment and activation of accessory cells by the intact bsAb is essential.

TNFalpha contributes to the antitumor activity of a bispecific, trifunctional antibody

Immunological cancer therapies focus on the activation of immune effector cells yielding a specific antitumor activity. Disseminated tumor cells are regarded as the origin of metastases and consequently their elimination is the central objective of adjuvant immune therapies. The use of bispecific antibodies is an approach that is regarded as promising in order to fight those disseminated tumor cells. Unfortunately, the efficiency of these antibodies is limited by the fact that they usually activate a single class of effector cell, thus not yielding optimal immune response. In addition, tumor cells may down-regulate the antibody's target molecule and escape recognition. We have recently described results with an intact bispecific molecule, BiUII, that represents a new class of intact antibodies. These antibodies, termed "triomab", provide an excellent antitumor activity in vitro, a fact that most probably is attributable to the simultaneous activation of different classes of immune effector cells. We have now investigated this antitumor activity in more detail and demonstrate here that at least a dual mechanism accounts for triomab-mediated killing of tumor cells: besides direct cell-mediated killing, triomab induces the production of TNFalpha in PBMCs at concentrations that induce apoptosis in target cells. This bystander effect may be of special interest for the clinical application of triomab in terms of killing of target antigen-negative tumor cells.