Intraperitoneal bispecific antibody (HEA125xOKT3) therapy inhibits malignant ascites production in advanced ovarian carcinoma

Bispecific Antibody Format and the Organization of Immunological Synapses in T Cell-Redirecting Strategies for Cancer Immunotherapy

T cell-redirecting strategies have emerged as effective cancer immunotherapy approaches. Bispecific antibodies (bsAbs) are designed to specifically recruit T cells to the tumor microenvironment and induce the assembly of the immunological synapse (IS) between T cells and cancer cells or antigen-presenting cells. The way that the quality of the IS might predict the effectiveness of T cell-redirecting strategies, including those mediated by bsAbs or by chimeric antigen receptors (CAR)-T cells, is currently under discussion. Here we review the organization of the canonical IS assembled during natural antigenic stimulation through the T cell receptor (TCR) and to what extent different bsAbs induce T cell activation, canonical IS organization, and effector function. Then, we discuss how the biochemical parameters of different formats of bsAbs affect the effectivity of generating an antigen-induced canonical IS. Finally, the quality of the IS assembled by bsAbs and monoclonal antibodies or CAR-T cells are compared, and strategies to improve bsAb-mediated T cell-redirecting strategies are discussed.

Immunotherapies of retinoblastoma: Effective methods for preserving vision in the future

Retinoblastoma is the most common intraocular tumor in children. Patients can be cured by enucleation, but it can lead to vision loss. Chemotherapy is the main method of treatment for RB currently. Unfortunately, chemoresistant and tumor metastasis often happen, resulting in a relatively poor prognosis. Therefore, immunotherapy becomes one of the optimal choices. Targeting not only tumor cells but also the active tumor microenvironment is a novel strategy for RB treatment. Here, we conclude several potential targets for RB immunotherapy, including gangliosides GD2, PD-1 and PD-L1, B7H3, EpCAM and SYK. We also review the techniques for CART, bispecific antibodies and genetically modified Dendritic cells according to the characteristics of different targets and discuss the feasibility of immunotherapy with different targets.

Combining forces to hit cancer stem cells: TRAIL-lymphocytes and EpCAMxCD3 bispecific antibody show efficacy against pancreatic cancer

TRAIL selectively kills cancer cells while bispecific antibody EpCAMxCD3 guides effector lymphocytes to cancer cells. Arming of ex vivo constructed TRAIL-lymphocytes with EpCAMxCD3 enhances contact time and affinity between lymphocytes and tumor cells and enforces tumor elimination. This boosts endogenous immune responses and augments the effect of cytotoxic tumor therapy.

Aptamers as potential therapeutic agents for ovarian cancer

Current therapy for ovarian cancer typically involves indiscriminate chemotherapies that can have severe off target effects on healthy tissue and are still plagued by aggressive recurrence. Recent shifts towards targeted therapies offer the possibility of circumventing the obstacles experienced by these traditional treatments. While antibodies are the pioneering agents in targeted therapies, clinical experience has demonstrated that their antitumor efficacy is limited due to their high immunogenicity, large molecular size, and costly and laborious production. In contrast, nucleic acid based chemical antibodies, also known as aptamers, are ideal for this application given their small size, lack of immunogenicity and in vitro production. As aptamers have begun to demonstrate their promise through targeting Epithelial Cell Adhesion Molecule (EpCAM), as well as a number of ovarian cancer biomarkers, in in vivo and in vitro models, their clinical applicability is slowly being realised. This review explores some of the current progress of aptamers targeting cancer biomarkers and their potential role as ovarian cancer therapeutics.

Fibroblast recruitment as a tool for ovarian cancer detection and targeted therapy

Metastatic ovarian cancer, the most lethal of gynecologic malignancies, is typically managed by debulking surgery, followed by chemotherapy. However, despite significant efforts, survival rate remains low. We have previously demonstrated, in mouse models, a specific systemic homing of labeled fibroblasts to solid ovarian tumors. Here, we demonstrate the feasibility of utilizing this specific homing of genetically modified fibroblasts for detection and targeted therapy of orthotopic metastatic ovarian carcinoma model in immune-deficient mice. Using an in vivo metastatic mouse model for ovarian cancer, we demonstrated that fibroblasts expressing fluorescent reporters injected intra-peritoneally, were specifically recruited to peritoneal tumor nodules (resulting in 93-100% co-localization). We further used fibroblasts over expressing the soluble receptor variant of VEGFR1 (s-Flt1). Mice bearing tumors were injected weekly with either control or s-Flt1 expressing fibroblasts. Injection of s-Flt1 expressing fibroblasts resulted in a significant reduction in the ascites volume, reduced vascularization of adherent metastases, and improved overall survival. Using fluorescently labeled fibroblasts for tumor detection with readily available intra-operative fluorescence imaging tools may be useful for tumor staging and directing biopsies or surgical efforts during exploratory or debulking surgery. Fibroblasts may serve as a beacon pointing to the otherwise invisible metastases in the peritoneal cavity of ovarian cancer patients. Utilizing the recruited fibroblasts also for targeted delivery of anti angiogenic or antitumor molecules may aid in controlling tumor progression. Thus, these results suggest a novel approach for targeting ovarian tumor metastases for both tumor detection and therapy.

Taking up Cancer Immunotherapy Challenges: Bispecific Antibodies, the Path Forward?

As evidenced by the recent approvals of Removab (EU, Trion Pharma) in 2009 and of Blincyto (US, Amgen) in 2014, the high potential of bispecific antibodies in the field of immuno-oncology is eliciting a renewed interest from pharmaceutical companies. Supported by rapid advances in antibody engineering and the development of several technological platforms such as Triomab or bispecific T cell engagers (BiTEs), the “bispecifics” market has increased significantly over the past decade and may occupy a pivotal space in the future. Over 30 bispecific molecules are currently in different stages of clinical trials and more than 70 in preclinical phase. This review focuses on the clinical potential of bispecific antibodies as immune effector cell engagers in the onco-immunotherapy field. We summarize current strategies targeting various immune cells and their clinical interests. Furthermore, perspectives of bispecific antibodies in future clinical developments are addressed.

Characterization of a bispecific FLT3 X CD3 antibody in an improved, recombinant format for the treatment of leukemia

FLT3 is a receptor-tyrosine-kinase that is expressed on leukemic cells of the myeloid and lymphoid lineage rather specifically. We here report on the construction and selection of bispecific FLT3 X CD3 antibodies in a new recombinant format, termed Fabsc, that resembles the normal antibody structure more closely than the well-established bispecific single chain (bssc)-format. Our preferred antibody, which emerged from an initial selection procedure utilizing different FLT3- and CD3-antibodies, contains the FLT3-antibody 4G8 and the CD3-antibody UCHT1. The 4G8 X UCHT1 Fabsc-antibody was found to be superior to a bssc-antibody with identical specificities with respect to (i) affinity to the target antigen FLT3, (ii) production yield by transfected cells, and (iii) the diminished formation of aggregates. T-cell activation in the presence and absence of cultured leukemic cells and killing of these cells was comparable for both molecules. In addition, the 4G8 X UCHT1 Fabsc-antibody was found to induce T-cell activation and efficient killing of leukemic blasts in primary peripheral blood mononuclear cell (PBMC) cultures of acute myeloid leukemia (AML) patients. In these experiments, the bispecific molecule was clearly superior to an Fc-optimized monospecific FLT3-antibody described previously, indicating that within PBMC of AML patients the recruitment of T cells is more effective than that of natural killer cells.

Re-challenge with catumaxomab in patients with malignant ascites: results from the SECIMAS study

Malignant ascites is a common phenomenon in cancer patients. It poses a great challenge to the clinician, because of limited treatment options and strong impairment of the quality of life of the often palliative patients. The SECIMAS study investigated the feasibility of a re-challenge with four catumaxomab intraperitoneal infusions in patients who had already received a first cycle of four infusions in the phase III CASIMAS study, which compared catumaxomab with and without prednisolone premedication. The primary endpoint was the proportion of patients who received at least three catumaxomab infusions. Secondary endpoints included a composite safety score (CSS) summarising the worst grades for the main catumaxomab-related adverse events (pyrexia, nausea, vomiting and abdominal pain), safety, efficacy and the occurrence of anti-drug antibodies (ADAs). Eight of nine screened patients received a second catumaxomab cycle. Compliance with a catumaxomab re-challenge was high: all eight patients (100%) received all four infusions. The median CSS was 3.0 versus 3.4 in CASIMAS. The tolerability profile of the second catumaxomab cycle was comparable to that of the first cycle. Median puncture-free survival (48 days) and overall survival (407 days) were longer than in CASIMAS (35 and 103 days, respectively), although median time to next puncture was shorter (60 vs. 97 days). Of six patients sampled, all were ADA positive at screening and remained ADA positive until the end of the study. The presence of ADAs did not affect catumaxomab's safety or efficacy. The CSS and tolerability profile for catumaxomab in SECIMAS were comparable to those in CASIMAS. The majority of patients benefitted from a second cycle of catumaxomab. A re-challenge seems to be feasible and safe for selected patients with recurrent malignant ascites due to carcinoma after a first cycle of catumaxomab.

A photosensitizer delivered by bispecific antibody redirected T lymphocytes enhances cytotoxicity against EpCAM-expressing carcinoma cells upon light irradiation

Recently conducted clinical trials have provided impressive evidence that chemotherapy resistant metastatic melanoma and several hematological malignancies can be cured using adoptive T cell therapy or T cell-recruiting bispecific antibodies. However, a significant fraction of patients did not benefit from these treatments. Here we have evaluated the feasibility of a novel combination therapy which aims to further enhance the killing potential of bispecific antibody-redirected T lymphocytes by using these cells as targeted delivery system for photosensitizing agents. For a first in vitro proof-of-concept study, ex vivo activated human donor T cells were loaded with a poly(styrene sulfonate) (PSS)-complex of the model photosensitizer 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (mTHPP). In the absence of light and when loading with the water-soluble PSS/mTHPP-complex occurred at a tolerable concentration, viability and cytotoxic function of loaded T lymphocytes were not impaired. When "drug-enhanced" T cells were co-cultivated with EpCAM-expressing human carcinoma cells, mTHPP was transferred to target cells. Notably, in the presence of a bispecific antibody, which cross-links effector and target cells thereby inducing the cytolytic activity of cytotoxic T lymphocytes, significantly more photosensitizer was transferred. Consequently, upon irradiation of co-cultures, redirected drug-loaded T cells were more effective in killing A549 lung and SKOV-3 ovarian carcinoma cells than retargeted unloaded T lymphocytes. Particularly, the additive approach using redirected unloaded T cells in combination with appropriate amounts of separately applied PSS/mTHPP was less efficient as well. Thus, by loading T lymphocytes with a stimulus-sensitive anti-cancer drug, we were able to enhance the cytotoxic capacity of carrier cells. Photosensitizer boosted T cells could open new perspectives for adoptive T cell therapy as well as targeted photodynamic therapy.

Role of the EpCAM (CD326) in prostate cancer metastasis and progression

Despite significant advances in surgery, radiotherapy and chemotherapy to treat prostate cancer (CaP), many patients die of secondary disease (metastases). Current therapeutic approaches are limited, and there is no cure for metastatic castration-resistant prostate cancer (CRPC). Epithelial cell adhesion molecule (EpCAM, also known as CD326) is a transmembrane glycoprotein that is highly expressed in rapidly proliferating carcinomas and plays an important role in the prevention of cell-cell adhesion, cell signalling, migration, proliferation and differentiation. Stably and highly expressed EpCAM has been found in primary CaP tissues, effusions and CaP metastases, making it an ideal candidate of tumour-associated antigen to detect metastasis of CaP cells in the circulation as well as a promising therapeutic target to control metastatic CRPC disease. In this review, we discuss the implications of the newly identified roles of EpCAM in terms of its diagnostic and metastatic relevance to CaP. We also summarize EpCAM expression in human CaP and EpCAM-mediated signalling pathways in cancer metastasis. Finally, emerging and innovative approaches to the management of the disease and expanding potential therapeutic applications of EpCAM for targeted strategies in future CaP therapy will be explored.

Cytotoxicity of cytokine-induced killer cells targeted by a bispecific antibody to gastric cancer cells

The aim of the present study was to investigate the cytotoxic activity of cytokine-induced killer (CIK) cells targeted by an epidermal growth factor receptor (EGFR)/CD3 bispecific antibody (BsAb) to the gastric cancer cell line SGC7901. A BsAb was constructed by chemically cross-linking a monoclonal antibody (McAb) against human CD3 with another McAb against human EGFR. An immunocytochemistry assay was performed to detect the expression of EGFR in SGC7901 cells. The cytotoxic activity of CIK cells targeted by the EGFR/CD3 BsAb was analyzed by the ⁵¹Cr release assay, Subsequently, a comparison of the cytotoxic activity between CIK cells targeted by EGFR/CD3 BsAb, CIK cells targeted by EGFR McAb or/and CD3 McAb and CIK cells was performed. The antineoplastic activity of the CIK cells directed using the EGFR/CD3 BsAb in vivo was analyzed by tumor growth and tumor reduction assays. The cell lysis rate of CIK cells targeted by the EGFR/CD3 BsAb was higher compared with those of CIK cells targeted by CD3 McAb only or by CD3 McAb and EGFR McAb. The lysis rates of the latter two groups were significantly higher than those of CIK cells targeted by EGFR McAb only and CIK cells (P<0.05). The mean tumor reduction using the administration of CIK cells directed by the EGFR/CD3 BsAb was higher than those of the other groups (P<0.05). The results indicate that the EGFR/CD3 BsAb is able to enhance the ability of CIK cells to bind to and kill gastric cancer cells in vitro and in vivo.

Therapeutic potential of amanitin-conjugated anti-epithelial cell adhesion molecule monoclonal antibody against pancreatic carcinoma

BACKGROUND

Human epithelial cell adhesion molecule (EpCAM) is overexpressed in many cancers. Anti-EpCAM antibodies have shown promise in preclinical studies, but showed no tumor regression in a recent phase II clinical trial. Therefore, we generated a novel anti-EpCAM antibody-drug conjugate and assessed whether it showed enhanced antitumor effects.

METHODS

Chemical cross-linking was conducted to covalently conjugate α-amanitin, a toxin known to inhibit DNA transcription, with chiHEA125, a chimerized anti-EpCAM monoclonal antibody, to generate the antibody-drug conjugate α-amanitin-glutarate-chiHEA125 (chiHEA125-Ama). Antiproliferative activity of chiHEA125-Ama was tested in human pancreatic (BxPc-3 and Capan-1), colorectal (Colo205), breast (MCF-7), and bile duct (OZ) cancer cell lines in vitro using [(3)H]-thymidine incorporation assay. Antitumor activity of chiHEA125-Ama was assessed in vivo in immunocompromised mice bearing subcutaneous human BxPc-3 pancreatic carcinoma xenograft tumors (n = 66 mice). Cell proliferation and apoptosis were evaluated in xenograft tumors by immunohistochemistry. All statistical tests were two-sided.

RESULTS

In all cell lines, chiHEA125-Ama reduced cell proliferation (mean half maximal inhibitory concentration [IC(50)] = 2.5 × 10(-10) to 5.4 × 10(-12) M). A single dose of chiHEA125-Ama inhibited BxPc-3 xenograft tumor growth (chiHEA125 [control, n = 4 mice] vs. chiHEA125-Ama [n = 6 mice], dose of 15 mg/kg with respect to IgG and 50 μg/kg with respect to α-amanitin, mean relative increase in tumor volume on day 16 = 884% vs. -79%, difference = 963%, 95% CI = 582% to 1344%, P = .019). Two higher doses of chiHEA125-Ama (100 μg/kg with respect to α-amanitin), administered 1 week apart (n = 10 mice per group), led to complete tumor regression in nine of 10 (90%) mice compared with chiHEA125, during the observation period of 16 days; increased apoptosis and reduced cell proliferation were observed in mice treated with chiHEA125-Ama.

CONCLUSION

This preclinical study suggests that anti-EpCAM antibody conjugates with α-amanitin have the potential to be highly effective therapeutic agents for pancreatic carcinomas and various EpCAM-expressing malignancies.

Targeting of cancer stem cell marker EpCAM by bispecific antibody EpCAMxCD3 inhibits pancreatic carcinoma

Patients with pancreatic cancer have a poor survival rate, and new therapeutic strategies are needed. Epithelial cell adhesion molecule (EpCAM), suggested as a marker for cancer stem cells, is over-expressed on most pancreatic tumour cells but not on normal cells and may be an ideal therapeutic target. We evaluated the anti-tumour efficiency of bispecific EpCAMxCD3 antibody linking tumour cells and T lymphocytes. In NOD SCID mice, EpCAMxCD3 had a long serum half-life (t_1/2∼ 7 days). EpCAMxCD3 significantly retarded growth of BxPC-3 pancreatic carcinoma xenografts. For mimicking a pancreatic cancer microenvironment in vitro, we used a three-dimensional tumour reconstruct system, in which lymphocytes were co-cultured with tumour cells and fibroblasts in a collagen matrix. In this in vivo–like system, EpCAMxCD3 potently stimulated production of the effector cytokines IFN-γ and TNF-α by extracorporally pre-activated lymphocytes. Moreover, compared with a bivalent anti-CD3 antibody, EpCAMxCD3 more efficiently activated the production of TNF-α and IFN-γ by non-stimulated peripheral blood mononuclear cells. Most excitingly, we demonstrate for the first time that EpCAMxCD3 induces prolonged contacts between lymphocytes and tumour cells, which may be the main reason for the observed anti-tumour effects. As an important prerequisite for future use in patients, EpCAMxCD3 did not alter lymphocyte migration as measured by time-lapse video microscopy. Our data may open a way to improve the immune response and treatment outcome in patients with pancreatic cancer.

From tumor immunosuppression to eradication: targeting homing and activity of immune effector cells to tumors

Unraveling the mechanisms used by the immune system to fight cancer development is one of the most ambitious undertakings in immunology. Detailed knowledge regarding the mechanisms of induction of tolerance and immunosuppression within the tumor microenvironment will contribute to the development of highly effective tumor eradication strategies. Research within the last few decades has shed more light on the matter. This paper aims to give an overview on the current knowledge of the main tolerance and immunosuppression mechanisms elicited within the tumor microenvironment, with the focus on development of effective immunotherapeutic strategies to improve homing and activity of immune effector cells to tumors.

Humoral response to catumaxomab correlates with clinical outcome: results of the pivotal phase II/III study in patients with malignant ascites

The trifunctional antibody catumaxomab is a targeted immunotherapy for the intraperitoneal treatment of malignant ascites. In a Phase II/III trial in cancer patients (n = 258) with malignant ascites, catumaxomab showed a clear clinical benefit vs. paracentesis and had an acceptable safety profile. Human antimouse antibodies (HAMAs), which could be associated with beneficial humoral effects and prolonged survival, may develop against catumaxomab as it is a mouse/rat antibody. This post hoc analysis investigated whether there was a correlation between the detection of HAMAs 8 days after the fourth catumaxomab infusion and clinical outcome. HAMA-positive and HAMA-negative patients in the catumaxomab group and patients in the control group were analyzed separately for all three clinical outcome measures (puncture-free survival, time to next puncture and overall survival) and compared to each other. There was a strong correlation between humoral response and clinical outcome: patients who developed HAMAs after catumaxomab showed significant improvement in all three clinical outcome measures vs. HAMA-negative patients. In the overall population in HAMA-positive vs. HAMA-negative patients, median puncture-free survival was 64 vs. 27 days (p < 0.0001; HR 0.330), median time to next therapeutic puncture was 104 vs. 46 days (p = 0.0002; HR 0.307) and median overall survival was 129 vs. 64 days (p = 0.0003; HR 0.433). Similar differences between HAMA-positive and HAMA-negative patients were seen in the ovarian, nonovarian and gastric cancer subgroups. In conclusion, HAMA development may be a biomarker for catumaxomab response and patients who developed HAMAs sooner derived greater benefit from catumaxomab treatment.

Intraperitoneal treatment with the trifunctional bispecific antibody Catumaxomab in patients with platinum-resistant epithelial ovarian cancer: a phase IIa study of the AGO Study Group

OBJECTIVE

The aim of this study was to select the best catumaxomab regimen for further investigation in ovarian cancer based on confirmed tumour response.

METHODS

Randomised open-label phase IIa study in women with platinum-resistant or -refractory epithelial ovarian cancer. Catumaxomab (6-hour intraperitoneal infusion on days 0, 3, 7 and 10) was administered at a low (10, 10, 10 and 10 μg) or high dose (10, 20, 50 and 100 μg). Responders were patients with either a complete (CR) or partial (PR) response.

RESULTS

Forty-five patients were randomised to receive either low dose (23) or high dose (22). There were no responders in the low-dose versus one patient (5%) in the high-dose group with a PR. In the low-dose group, two patients (9%) had stable disease compared with five patients (23%) in the high-dose group. Catumaxomab was well tolerated and there was no difference between the dose groups in the incidence of treatment-induced adverse events, the most common of which were gastrointestinal and injection-site reactions.

CONCLUSION

Catumaxomab had modest activity in platinum-resistant ovarian cancer. The high-dose regimen was associated with a slightly better therapeutic index than the low dose regimen.

Novel monoclonal antibodies for cancer treatment: the trifunctional antibody catumaxomab (removab)

The trifunctional antibody (trAb) catumaxomab is characterized by a unique ability to bind three different cell types: tumor cells; T-cells; and accessory cells. It binds to epithelial cell adhesion molecule (EpCAM) on tumor cells, the CD3 antigen on T-cells, and to type I, IIa, and III Fcγ receptors (FcγRs) on accessory cells (e.g. natural killer cells, dendritic cells, and macrophages). Catumaxomab exerts its anti-tumor effects via T-cell-mediated lysis, antibody-dependent, cell-mediated cytotoxicity, and phagocytosis via activation of FcγR-positive accessory cells. Catumaxomab represents a self-supporting system, as no additional immune cell activation is required for tumor eradication. The efficacy and safety of catumaxomab have been demonstrated in a pivotal phase II/III study in malignant ascites (MA) and supporting phase I/II studies. It is administered as four intraperitoneal (i.p.) infusions of 10, 20, 50, and 150 µg on days 0, 3, 7, and 10, respectively. Catumaxomab was approved for the i.p. treatment of MA in patients with EpCAM-positive carcinomas where standard therapy is not available or no longer feasible in the European Union in April 2009. It is the first trAb and the first drug in the world approved specifically for the treatment of MA. Catumaxomab was awarded the Galen of Pergamon Prize, which recognizes pharmacological research for developing new and innovative drugs and diagnostics, in the specialist care category in 2010. The use of catumaxomab in other indications and additional routes of administration are currently being investigated to further exploit its therapeutic potential in EpCAM-positive carcinomas.

Epithelial cell adhesion molecule expression (CD326) in cancer: a short review

Epithelial cell adhesion molecule (EpCAM, CD326) is a pleiotropic molecule that potentially offers therapeutic applications in cancer treatment. Initially described as a dominant surface antigen on human colon carcinoma, it is a transmembrane glycoprotein mediating epithelial-specific intercellular cell-adhesion. Recent data suggest that EpCAM is also involved in cell signaling, migration, proliferation and differentiation. Since EpCAM is expressed exclusively in epithelia and epithelial-derived neoplasms, EpCAM can be used as diagnostic marker. Testing for EpCAM is based on morphology and phenotypical staining and can be performed with primary carcinoma tissue and cells harvested from malignant effusions. Stable or highly expressed EpCAM has been detected in most adenocarcinomas and has also been found in metastases, malignant effusions, and cancer stem cells. EpCAM may thus be an ideal tumor antigen candidate to detect circulating and metastasizing cancer cells by microchip technologies. In certain tumor types overexpression was linked to advanced stage of disease and worse overall survival, suggesting EpCAM as a potential prognostic marker. In addition to its diagnostic and prognostic role, EpCAM's broad expression and apparent involvement in tumorigenesis and metastasis point to its potential as a target for immunotherapeutic strategies. The first EpCAM targeting, trifunctional antibody catumaxomab (Removab®) has shown clear clinical benefits in treatment of malignant ascites associated with EpCAM positive carcinomas. Further research and clinical studies should unravel EpCAM's complex role in oncological processes, and expand potential therapeutic applications of EpCAM targeted strategies.

The trifunctional antibody catumaxomab for the treatment of malignant ascites due to epithelial cancer: Results of a prospective randomized phase II/III trial

Malignant ascites is a common manifestation of advanced cancers, and treatment options are limited. The trifunctional antibody catumaxomab (anti-epithelial cell-adhesion molecule x anti-CD3) represents a targeted immunotherapy for the intraperitoneal (i.p.) treatment of malignant ascites secondary to epithelial cancers. In this phase II/III trial (EudraCT 2004-000723-15; NCT00836654), cancer patients (n = 258) with recurrent symptomatic malignant ascites resistant to conventional chemotherapy were randomized to paracentesis plus catumaxomab (catumaxomab) or paracentesis alone (control) and stratified by cancer type (129 ovarian and 129 nonovarian). Catumaxomab was administered as an i.p. infusion on Days 0, 3, 7 and 10 at doses of 10, 20, 50 and 150 μg, respectively. The primary efficacy endpoint was puncture-free survival. Secondary efficacy parameters included time to next paracentesis, ascites signs and symptoms and overall survival (OS). Puncture-free survival was significantly longer in the catumaxomab group (median 46 days) than the control group (median 11 days) (hazard ratio = 0.254: p < 0.0001) as was median time to next paracentesis (77 versus 13 days; p < 0.0001). In addition, catumaxomab patients had fewer signs and symptoms of ascites than control patients. OS showed a positive trend for the catumaxomab group and, in a prospectively planned analysis, was significantly prolonged in patients with gastric cancer (n = 66; 71 versus 44 days; p = 0.0313). Although adverse events associated with catumaxomab were frequent, they were manageable, generally reversible and mainly related to its immunologic mode of action. Catumaxomab showed a clear clinical benefit in patients with malignant ascites secondary to epithelial cancers, especially gastric cancer, with an acceptable safety profile.

[Antibody engineering: barnase-barstar module as a molecular constructor]

Today, antibody engineering for clinical applications is a rapidly progressing field of science and a big business. The basic functions of an antibody can be spatially differentiated and attributed to various structural domains of a molecule. Therefore, each of them may be an object for engineering with the aim of using a definite antibody function. In this sense, the potential of antibodies is unique. In this article, recent achievements and current problems of antibody engineering are briefly reviewed. The main attention is focused on a molecular constructor that allows for obtaining, with the help of a versatile barnase-barstar module, mono- and multiva-lent miniantibodies and their derivatives with outlined properties.

Induction of long-lasting antitumor immunity by concomitant cell therapy with allogeneic lymphocytes and trifunctional bispecific antibody

OBJECTIVE

Use of a trifunctional bispecific antibody (trAb) given concomitantly with allogeneic cell therapy to achieve an anti tumor effect without graft-vs-host disease (GVHD).

MATERIALS AND METHODS

A trAb-directed against murine CD3 and human epithelial cell adhesion molecule (EpCAM) (BiLu), was given alone or concomitantly with interleukin (IL)-2-activated (LAK) H-2(b) donor splenocytes to H-2(d/b) mice inoculated with murine melanoma cells transfected with human EpCAM.

RESULTS

A total of 32/38 mice treated with BiLu and LAK splenocytes, were tumor-free survivors without GVHD for >200 days following inoculation of a 100% lethal tumor dose (5 x 10(4)). Of 28 disease-free surviving mice previously treated with LAK splenocytes and BiLu, 24 mice proved resistance to a second tumor challenge of 10(4) cells given >210 days following the first tumor inoculation with no evidence of disease for >150 days. In contrast, only 4 of 13 disease-free survivor mice treated with naïve splenocytes and BiLu, and 5 of 10 disease-free survivor controls treated with BiLu only, resisted the second tumor challenge. Induction of antitumor immunity was more efficient and long-lasting (>150 days) in mice previously injected with a lethal tumor cell dose of 5 x 10(4) cells than in mice previously inoculated with 5 x 10(3) tumor cells.

CONCLUSION

Concomitantly treatment of allogeneic LAK cells and trAb-induced an efficient long-lasting antitumor immunity. Considering the documented efficacy of anti-EpCAM bispecific antibody in various metastatic cancers, clinical application of our approach may be justified in patients with minimal residual disease at high risk for tumor recurrence.

Cytokine-induced killer cells targeted by the novel bispecific antibody CD19xCD5 (HD37xT5.16) efficiently lyse B-lymphoma cells

Due to their dual binding capacity, bispecific antibodies (bsAb) can be used to cross-link cytotoxic effector cells with malignant targets and may thereby improve adoptive immunotherapy. In this study, the development and preclinical testing of the quadroma-derived bsAb HD37xT5.16 of the specificity CD19xCD5 is reported. Effector cells used were a population of ex vivo expanded and activated T cells called cytokine-induced killer (CIK) cells expressing CD5. When combined with CIK cells, the cytolytic potency of HD37xT5.16 against CD19 positive B cell lymphoma lines was comparable to that observed with a previously described CD19xCD3 bsAb. Further on, we could demonstrate that bsAb CD19xCD5, in contrast to its CD3-binding counterpart, does not induce proliferation of resting T cells and causes only little activation-induced cell death. Therefore, this novel bsAb binding effector T cells via CD5 may be particularly useful in combination with adoptive transfer of ex vivo activated T cells, e.g., in the setting of adoptive immunotherapy after allogeneic stem cell transplantation. The in vitro studies outlined here support the experimental use of bsAb HD37xT5.16 in preclinical in vivo models for evaluation of its safety and efficacy profile.

The effect of dexamethasone on polyclonal T cell activation and redirected target cell lysis as induced by a CD19/CD3-bispecific single-chain antibody construct

BiTE molecules comprise a new class of bispecific single-chain antibodies redirecting previously unstimulated CD8+ and CD4+ T cells for the elimination of target cells. One example is MT103 (MEDI-538; bscCD19xCD3), a CD19-specific BiTE that can induce lysis of normal and malignant B cells at low picomolar concentrations, which is accompanied by T cell activation. Here, we explored in cell culture the impact of the glucocorticoid derivative dexamethasone on various activation parameters of human T cells in response to MT103. In case cytokine-related side effects should occur with BiTE molecules and other T cell-based approaches during cancer therapy it is important to understand whether glucocorticoids do interfere with the cytotoxic potential of T cells. We found that MT103 induced in the presence of target cells secretion by peripheral T cells of interleukin (IL)-2, tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), IL-6, IL-10 and IL-4 into the cell culture medium. Production of all studied cytokines was effectively reduced by dexamethasone at a concentration between 1 and 3x10(-7) M. In contrast, upregulation of activation markers CD69, CD25, CD2 and LFA-1 on both CD4+ and CD8+ T cells, and T cell proliferation were barely affected by the steroid hormone analogue. Most importantly, dexamethasone did not detectably inhibit the cytotoxic activity of MT103-activated T cells against a human B lymphoma line as investigated with lymphocytes from 12 human donors. Glucocorticoids thus qualify as a potential co-medication for therapeutic BiTE molecules and other cytotoxic T cell therapies for treatment of cancer.

Effective relief of malignant ascites in patients with advanced ovarian cancer by a trifunctional anti-EpCAM x anti-CD3 antibody: a phase I/II study

PURPOSE

Malignant ascites in ovarian carcinoma patients is associated with poor prognosis and reduced quality of life. The trifunctional antibody catumaxomab (anti-EpCAM x anti-CD3) enhances the antitumor activity by redirecting T cells and Fcgamma receptor I/III--positive accessory cells to the tumor. This multicenter phase I/II dose-escalating study investigated tolerability and efficacy of i.p. catumaxomab application in ovarian cancer patients with malignant ascites containing epithelial cell adhesion molecule (EpCAM)--positive tumor cells.

EXPERIMENTAL DESIGN

Twenty-three women with recurrent ascites due to pretreated refractory ovarian cancer were treated with four to five i.p. infusions of catumaxomab in doses of 5 to 200 microg within 9 to 13 days.

RESULTS

The maximum tolerated dose was defined at 10, 20, 50, 200, and 200 microg for the first through fifth doses. Side effects included transient fever (83%), nausea (61%), and vomiting (57%), mostly CTCAE (Common Terminology Criteria for Adverse Events) grade 1 or 2. A total of 39 grade 3 and 2 grade 4 treatment-related adverse events (AE), 9 of them after the highest dose level (200 microg), were observed in 16 patients. Most AEs were reversible without sequelae. Treatment with catumaxomab resulted in significant and sustained reduction of ascites flow rate. A total of 22/23 patients did not require paracentesis between the last infusion and the end of study at day 37. Tumor cell monitoring revealed a reduction of EpCAM-positive malignant cells in ascites by up to 5 log.

CONCLUSION

I.p. immunotherapy with catumaxomab prevented the accumulation of ascites and efficiently eliminated tumor cells with an acceptable safety profile. This suggests that catumaxomab is a promising treatment option in ovarian cancer patients with malignant ascites.

Pattern and prognostic factors in patients with malignant ascites: a retrospective study

BACKGROUND

Malignant ascites is a manifestation of end stage events in a variety of cancers and associated with a poor prognosis. We evaluated the pattern of cancers causing malignant ascites and factors affecting survival.

PATIENTS AND METHODS

Patients coded with the International Classification of Diseases-9 coding system for malignant ascites over a 2-year period were reviewed. The clinicopathological data and patients' survival were compared among cancer groups.

RESULTS

There were 209 patients (140 females and 69 males), median age being 67 (30-98) years. The commonest cancer was ovarian followed by gastrointestinal (GI) cancers. Fifty-eight per cent of the patients had symptoms related to the ascites. Liver metastases were significantly commoner in the GI cancers (P = 0.0001). Fifty-four per cent of our patients presented with ascites at the initial diagnosis of their cancer. Paracentesis was given to 112, diuretics to 70 and chemotherapy to 103 patients. The median survival following diagnosis of ascites was 5.7 months. Ovarian cancer favoured longer survival while low serum albumin, low serum protein and liver metastases adversely affected survival. The independent prognostic factors for survival were cancer type, liver metastases and serum albumin.

CONCLUSION

The identified independent prognostic factors should be used to select patients for multimodality therapy for adequate palliation.

Targeting gastrin-releasing peptide receptors on small cell lung cancer cells with a bispecific molecule that activates polyclonal T lymphocytes

PURPOSE

Gastrin-releasing peptide (GRP) is a growth factor for small cell lung cancer (SCLC). GRP belongs to the bombesin peptide family and has significant homology to bombesin. We constructed a bispecific molecule, OKT3xAntag2, by conjugating a monoclonal antibody OKT3 (anti-CD3) with a bombesin/GRP antagonist (Antag2) and evaluated cytotoxicity against SCLC cells.

EXPERIMENTAL DESIGN

We tested binding of the bispecific molecule to SCLC cell lines and T cells by flow cytometry, antibody-dependent cellular cytotoxicity (ADCC) of SCLC cells in vitro and in a murine SCLC xenograft model. We studied SCLC apoptosis and necrosis during ADCC and the activity and cleavage of caspase-3, caspase-9, and poly(ADP-ribose) polymerase (PARP).

RESULTS

The bispecific molecule functions as a cross-linker between T cells and SCLC cells, induces T cell activation, and mediates ADCC of SCLC cells; 40% to 80% growth inhibition of SCLC cells mediated by the bispecific molecule at low effector to target cell ratios was achieved. Activation of T cells by the bispecific molecule resulted in significant increases in IFNgamma production and apoptosis and necrosis of SCLC cells associated with cleavage of PARP and caspase-3. Targeted immunotherapy with the bispecific molecule-armed human T cells significantly reduced SCLC tumor burdens in a mouse model.

CONCLUSION

The bispecific molecule OKT3xAntag2 mediates growth inhibition and apoptosis of SCLC cells by activated T cells through activation and cleavage of caspase-3 and PARP in vitro and in vivo. Clinical trials of this bispecific molecule through adoptive transfer of ex vivo activated T cells in GRP receptor-positive tumors, such as SCLC, are warranted.

Use of trifunctional bispecific antibodies to prevent graft versus host disease induced by allogeneic lymphocytes

A trifunctional bispecific antibody (BiLu) directed against murine CD3 and human epithelial-cell adhesion molecule (EpCAM) was tested for its ability to improve cell-mediated adoptive immunotherapy in a murine model of B16 melanoma cells transfected with human EpCAM. Intraperitoneal inoculation of naive C57BL/6 (C57) splenocytes induced lethal graft versus host disease (GVHD) in 85% to 97% of sublethally irradiated (BALB/c × C57BL/6) F1 (F1) hosts inoculated intraperitoneally with a sublethal or lethal dose of melanoma cells. BiLu antibodies given intraperitoneally concomitantly with alloreactive C57 cells effectively prevented GVHD-related and tumor-related death in 16 of 25 F1 mice inoculated with a sublethal tumor-cell dose and in 10 of 20 mice inoculated with a lethal tumor-cell dose over a follow-up period of more than 200 days. BiLu treatment also efficiently prevented severe GVHD, which was induced by high doses of BALB/c-derived splenocytes. Trifunctional bispecific antibodies (TbsAbs) capable of cross-linking T lymphocytes, natural killer, and other FcγR-positive effector cells, via their Fc region, to the tumor cells may be applied together with adoptive allogeneic-cell therapy to maximize antitumor responses while acting on GVHD in patients with minimal residual disease.

Immunotherapy of malignant ascites with trifunctional antibodies

A new class of intact bispecific antibodies shows unmet effector qualities by activation of not only T cells but also simultaneous activation of Fcgamma receptor type I/III+ cells (macrophages, NK-cells and DC). These trifunctional antibodies (trAb) lead to efficient specific killing of targeted tumor cells without any pre- or co-stimulation. This concept was investigated in vivo in patients with malignant ascites in a clinical situation that allowed monitoring of tumor cell elimination and correlation with clinical effects. In a prospective study, 8 patients with malignant ascites due to peritoneal carcinomatosis were treated with intraperitoneal application of trAb, which bound either the EpCAM- or Her2/neu-antigen on tumor cells. Treatment consisted of 4-6 applications within 9-23 days with a total amount of 145-940 microg. Seven of eight patients required no further paracentesis during follow-up or until death with a mean paracentesis-free interval of 38 weeks (median = 21.5, range = 4-136). Tumor cell monitoring showed a complete elimination of tumor cells in ascites already at total doses as low as 40-140 microg. Clinical response with disappearance of ascites accumulation was seen in all patients, which was correlated with elimination of tumor cells (p = 0.0014). Severe adverse events were not observed. Clinically relevant side effects were fever, moderate abdominal pain and skin reactions. Intraperitoneal immunotherapy with trAb showed convincing efficacy in patients with malignant ascites. This treatment offers new therapeutic options for patients with peritoneal carcinomatosis.

Tolerance and cancer: mechanisms of tumor evasion and strategies for breaking tolerance

The development of malignant disease might be seen as a failure of immune surveillance. However, not all tumors are naturally immunogenic, and even among those that are immunogenic, the uncontrolled rapid growth of a tumor may sometimes out-run a robust immune response. Nevertheless, recent evidence suggests that mechanisms of tolerance that normally exist to prevent autoimmune disease may also preclude the development of an adequate antitumor response and that tumors themselves have the ability to thwart the development of effective immune responses against their antigens. A major challenge has been to develop approaches to breaking this tolerance in tumor-bearing hosts, and recent advances in our understanding of antigen presentation and tolerance have led to some promising strategies. An alternative approach is to use T cells from nontumor-bearing, allogeneic hosts in the form of lymphocyte infusions, with or without hematopoietic cell transplantation. Immunotherapy may occur in this setting via the response of nontolerant, tumor antigen-specific T cells from nontumor-bearing hosts or via the powerful destructive effect of an alloresponse directed against antigens shared by malignant cells in the recipient. Approaches to exploiting this beneficial effect without the deleterious consequence of graft-versus-host disease in allogeneic hematopoietic cell recipients are discussed.

Future directions in the management of ovarian cancer

As investigators at the bench define the oncogenic pathways involved in ovarian cancer growth and invasion, clinical scientists will develop therapies to target these important pathways. The approach to the treatment of ovarian cancer will change to focus on strategies designed to eliminate minimal residual disease after primary therapy and in this way cure the disease. Concepts of consolidation after standard adjuvant chemotherapy and maintenance regimens will start to be evaluated for clinical efficacy. In addition, the focus on recurrent disease may change from repeated cytotoxic approaches to regimens chosen to prevent invasion or the development of drug resistance, changing the approach to ovarian cancer recurrence to a treatment plan of managing a chronic, but not imminently terminal, disease.

Efficient tumor cell lysis by autologous, tumor-resident T lymphocytes in primary ovarian cancer samples by an EP-CAM-/CD3-bispecific antibody

The epithelial cell adhesion molecule (Ep-CAM) is expressed on the surface of most human carcinomas, including ovarian, breast, lung, prostate and colorectal carcinoma. Ep-CAM was shown to be a valid target for monoclonal antibody-based therapies. We have investigated whether an Ep-CAM-/CD3-bispecific single-chain antibody called bscEp-CAM x CD3 is effective in tumor cell elimination within the cellular microenvironment of primary ovarian cancer tissue. The ex vivo elimination of ovarian cancer cells in tumor preparations from 21 patients was monitored by flow cytometry using Ep-CAM/CA-125 double-labeling or Ep-CAM single-labeling combined with propidium iodide uptake of cells. Methodology was established by the ovarian cancer cell line OvCAR. A total of 17 (81%) patient samples showed a dose-dependent tumor cell elimination by bscEp-CAM x CD3. High and specific tumor cell lysis was seen at bscEp-CAM x CD3 concentrations as low as 1 ng/ml, at very low effector:target ratios and in the absence of T cell costimulation. The high efficacy of the bispecific antibody may be due to the non-restricted activation of tumor-resident cytotoxic T lymphocytes. In clinical trials, the ex vivo data with the T cell-recruiting bispecific antibody bscEp-CAM x CD3 may translate into a high response rate and efficacy of tumor cell elimination.