Combination of GD2-directed bispecific trifunctional antibody therapy with Pd-1 immune checkpoint blockade induces anti-neuroblastoma immunity in a syngeneic mouse model.

Introduction: Despite advances in treating high-risk neuroblastoma, 50-60% of patients still suffer relapse, necessitating new treatment options. Bispecific trifunctional antibodies (trAbs) are a promising new class of immunotherapy. TrAbs are heterodimeric IgG-like molecules that bind CD3 and a tumor-associated antigen simultaneously, whereby inducing a TCR-independent anti-cancer T cell response. Moreover, via their functional Fc region they recruit and activate cells of the innate immune system like antigen-presenting cells potentially enhancing induction of adaptive tumor-specific immune responses. Methods: We used the SUREK trAb, which is bispecific for GD2 and murine Cd3. Tumor-blind trAb and the monoclonal ch14.18 antibody were used as controls. A co-culture model of murine dendritic cells (DCs), T cells and a neuroblastoma cell line was established to evaluate the cytotoxic effect and the T cell effector function in vitro. Expression of immune checkpoint molecules on tumor-infiltrating T cells and the induction of an anti-neuroblastoma immune response using a combination of whole cell vaccination and trAb therapy was investigated in a syngeneic immunocompetent neuroblastoma mouse model (NXS2 in A/J background). Finally, vaccinated mice were assessed for the presence of neuroblastoma-directed antibodies. We show that SUREK trAb-mediated effective killing of NXS2 cells in vitro was strictly dependent on the combined presence of DCs and T cells. Results: Using a syngeneic neuroblastoma mouse model, we showed that vaccination with irradiated tumor cells combined with SUREK trAb treatment significantly prolonged survival of tumor challenged mice and partially prevent tumor outgrowth compared to tumor vaccination alone. Treatment led to upregulation of programmed cell death protein 1 (Pd-1) on tumor infiltrating T cells and combination with anti-Pd-1 checkpoint inhibition enhanced the NXS2-directed humoral immune response. Conclusion: Here, we provide first preclinical evidence that a tumor vaccination combined with SUREK trAb therapy induces an endogenous anti-neuroblastoma immune response reducing tumor recurrence. Furthermore, a combination with anti-Pd-1 immune checkpoint blockade might even further improve this promising immunotherapeutic concept in order to prevent relapse in high-risk neuroblastoma patients.

Removal of EpCAM-positive tumor cells from blood collected during major oncological surgery using the Catuvab device- a pilot study.

BACKGROUND: Intraoperative blood salvage (IBS) is regarded as an alternative to allogeneic blood transfusion excluding the risks associated with allogeneic blood. Currently, IBS is generally avoided in tumor surgeries due to concern for potential metastasis caused by residual tumor cells in the erythrocyte concentrate. METHODS: The feasibility, efficacy and safety aspects of the new developed Catuvab procedure using the bispecific trifunctional antibody Catumaxomab was investigated in an ex-vivo pilot study in order to remove residual EpCAM positive tumor cells from the autologous erythrocyte concentrates (EC) from various cancer patients, generated by a IBS device. RESULTS: Tumor cells in intraoperative blood were detected in 10 of 16 patient samples in the range of 69-2.6 × 105 but no residual malignant cells in the final erythrocyte concentrates after Catuvab procedure. IL-6 and IL-8 as pro-inflammatory cytokines released during surgery, were lowered in mean 28-fold and 52-fold during the Catuvab procedure, respectively, whereas Catumaxomab antibody was detected in 8 of 16 of the final EC products at a considerable decreased and uncritical residual amount (37 ng in mean). CONCLUSION: The preliminary study results indicate efficacy and feasibility of the new medical device Catuvab allowing potentially the reinfusion of autologous erythrocyte concentrates (EC) produced by IBS device during oncological high blood loss surgery. An open-label, multicenter clinical study on the removal of EpCAM-positive tumor cells from blood collected during tumor surgery using the Catuvab device is initiated to validate these encouraging results.

GD2-directed bispecific trifunctional antibody outperforms dinutuximab beta in a murine model for aggressive metastasized neuroblastoma.

BACKGROUND: Neuroblastoma is the most common extracranial solid tumor of childhood. Patients with high-risk disease undergo extremely aggressive therapy and nonetheless have cure rates below 50%. Treatment with the ch14.18 monoclonal antibody (dinutuximab beta), directed against the GD2 disialoganglioside, improved 5-year event-free survival in high-risk patients when administered in postconsolidation therapy and was recently implemented in standard therapy. Relapse still occurred in 57% of these patients, necessitating new therapeutic options. Bispecific trifunctional antibodies (trAbs) are IgG-like molecules directed against T cells and cancer surface antigens, redirecting T cells (via their CD3 specificity) and accessory immune cells (via their functioning Fc-fragment) toward tumor cells. We sought proof-of-concept for GD2/CD3-directed trAb efficacy against neuroblastoma. METHODS: We used two GD2-specific trAbs differing only in their CD3-binding specificity: EKTOMUN (GD2/human CD3) and SUREK (GD2/mouse Cd3). This allowed trAb evaluation in human and murine experimental settings. Tumor-blind trAb and the ch14.18 antibody were used as controls. A coculture model of human peripheral blood mononuclear cells (PBMCs) and neuroblastoma cell lines was established to evaluate trAb antitumor efficacy by assessing expression of T-cell surface markers for activation, proinflammatory cytokine release and cytotoxicity assays. Characteristics of tumor-infiltrating T cells and response of neuroblastoma metastases to SUREK treatment were investigated in a syngeneic immunocompetent neuroblastoma mouse model mimicking minimal residual disease. RESULTS: We show that EKTOMUN treatment caused effector cell activation and release of proinflammatory cytokines in coculture with neuroblastoma cell lines. Furthermore, EKTOMUN mediated GD2-dependent cytotoxic effects in human neuroblastoma cell lines in coculture with PBMCs, irrespective of the level of target antigen expression. This effect was dependent on the presence of accessory immune cells. Treatment with SUREK reduced the intratumor Cd4/Cd8 ratio and activated tumor infiltrating T cells in vivo. In a minimal residual disease model for neuroblastoma, we demonstrated that single-agent treatment with SUREK strongly reduced or eliminated neuroblastoma metastases in vivo. SUREK as well as EKTOMUN demonstrated superior tumor control compared with the anti-GD2 antibody, ch14.18. CONCLUSIONS: Here we provide proof-of-concept for EKTOMUN preclinical efficacy against neuroblastoma, presenting this bispecific trAb as a promising new agent to fight neuroblastoma.

First time intravesically administered trifunctional antibody catumaxomab in patients with recurrent non-muscle invasive bladder cancer indicates high tolerability and local immunological activity.

Transurethral resection of the tumor (TUR-B) followed by adjuvant intravesical treatment with cytostatic drugs or Bacillus Calmette-Guérin (BCG) as standard therapy of non-muscle-invasive bladder cancer (NMIBC) is associated with a high recurrence rate of about 60-70%, considerable side effects and requires close monitoring. Alternative treatment options are warranted. Two patients with epithelial cell adhesion molecule (EpCAM)-positive recurrent non-muscle invasive bladder cancer were treated the first time by an intravesical administration of the trifunctional bispecific EpCAM targeting antibody catumaxomab (total dosage of 470 and 1120 µg, respectively). The binding and killing activity of catumaxomab in urine milieu was evaluated in vitro. In contrast to its previous systemic application catumaxomab was well tolerated without any obvious signs of toxicity. Relevant cytokine plasma levels were not detected and no significant systemic drug release was observed. The induction of a human anti-mouse-antibody (HAMA) reaction was either absent or untypically weak contrary to the high immunogenicity of intraperitoneal applied catumaxomab. Tumor cells that were detectable in urine patient samples disappeared after catumaxomab therapy. Endoscopically confirmed recurrence-free intervals were 32 and 25 months. Our data suggest that intravesical administration of catumaxomab in NMIBC is feasible, safe and efficacious, thus arguing for further clinical development of catumaxomab in this indication.

Randomised phase II trial to investigate catumaxomab (anti-EpCAM × anti-CD3) for treatment of peritoneal carcinomatosis in patients with gastric cancer.

BACKGROUND: Peritoneal carcinomatosis (PC) represents an unfavourable prognostic factor for patients with gastric cancer (GC). Intraperitoneal treatment with the bispecific and trifunctional antibody catumaxomab (EpCAM, CD3), in addition to systemic chemotherapy, could improve elimination of PC. METHODS: This prospective, randomised, phase II study investigated the efficacy of catumaxomab followed by chemotherapy (arm A, 5-fluorouracil, leucovorin, oxaliplatin, docetaxel, FLOT) or FLOT alone (arm B) in patients with GC and PC. Primary endpoint was the rate of macroscopic complete remission (mCR) of PC at the time of second diagnostic laparoscopy/laparotomy prior to optional surgery. RESULTS: Median follow-up was 52 months. Out of 35 patients screened, 15 were allocated to arm A and 16 to arm B. mCR rate was 27% in arm A and 19% in arm B (p = 0.69). Severe side effects associated with catumaxomab were nausea, infection, abdominal pain, and elevated liver enzymes. Median progression-free (6.7 vs. 5.4 months, p = 0.71) and overall survival (13.2 vs. 13.0 months, p = 0.97) were not significantly different in both treatment arms. CONCLUSIONS: Addition of catumaxomab to systemic chemotherapy was feasible and tolerable in advanced GC. Although the primary endpoint could not be demonstrated, results are promising for future investigations integrating intraperitoneal immunotherapy into a multimodal treatment strategy.

Potent CD4+ T cell-associated antitumor memory responses induced by trifunctional bispecific antibodies in combination with immune checkpoint inhibition.

Combinatorial approaches of immunotherapy hold great promise for the treatment of malignant disease. Here, we examined the potential of combining an immune checkpoint inhibitor and trifunctional bispecific antibodies (trAbs) in a preclinical melanoma mouse model using surrogate antibodies of Ipilimumab and Catumaxomab, both of which have already been approved for clinical use. The specific binding arms of trAbs redirect T cells to tumor cells and trigger direct cytotoxicity, while the Fc region activates accessory cells eventually giving rise to a long-lasting immunologic memory. We show here that T cells redirected to tumor cells by trAbs strongly upregulate CTLA-4 expression in vitro and in vivo. This suggested that blocking of CTLA-4 in combination with trAb treatment enhances T-cell activation in a tumor-selective manner. However, when mice were challenged with melanoma cells and subsequently treated with antibodies, there was only a moderate beneficial effect of the combinatorial approach in vivo with regard to direct tumor destruction in comparison to trAb therapy alone. By contrast, a significantly improved vaccination effect was obtained by CTLA-4 blocking during trAb-dependent immunization. This resulted in enhanced rejection of melanoma cells given after pre-immunization. The improved immunologic memory induced by the combinatorial approach correlated with an increased humoral antitumor response as measured in the sera and an expansion of CD4+ memory T cells found in the spleens.

Efficacy and Tolerability of a GD2-Directed Trifunctional Bispecific Antibody in a Preclinical Model: Subcutaneous Administration Is Superior to Intravenous Delivery.

Trifunctional bispecific antibodies (trAb) are novel anticancer drugs that recruit and activate different types of immune effector cells at the targeted tumor. Thus, tumor cells are effectively eliminated and a long-lasting tumor-specific T-cell memory is induced. The trAb Ektomab is directed against human CD3 on T cells and the tumor-associated ganglioside GD2, which is an attractive target for immunotherapy of melanoma in humans. To optimize clinical applicability, we studied different application routes with respect to therapeutic efficacy and tolerability by using the surrogate trAb Surek (anti-GD2 × anti-murine CD3) and a murine melanoma engineered to express GD2. We show that subcutaneous injection of the trAb is superior to the intravenous delivery pathway, which is the standard application route for therapeutic antibodies. Despite lower plasma levels after subcutaneous administration, the same tumor-protective potential was observed in vivo compared with intravenous administration of Surek. However, subcutaneously delivered Surek showed better tolerability. This could be explained by a continuous release of the antibody leading to constant plasma levels and a delayed induction of proinflammatory cytokines. Importantly, the induction of counter-regulatory mechanisms was reduced after subcutaneous application. These findings are relevant for the clinical application of trifunctional bispecific antibodies and, possibly, also other immunoglobulin constructs. Mol Cancer Ther; 14(8); 1877-83. ©2015 AACR.

Immunotherapy with the trifunctional anti-CD20 x anti-CD3 antibody FBTA05 (Lymphomun) in paediatric high-risk patients with recurrent CD20-positive B cell malignancies.

Children with B cell malignancies refractory to standard therapy are known to have a poor prognosis and very limited treatment options. Here, we report on the treatment and follow-up of ten patients diagnosed with relapsed or refractory mature B-cell Non Hodgkin Lymphoma (B-NHL), Burkitt leukaemia (B-AL) or pre B-acute lymphoblastic leukaemia (pre B-ALL). All children were treated with FBTA05 (now designated Lymphomun), an anti-CD3 x anti-CD20 trifunctional bispecific antibody (trAb) in compassionate use. Within individual treatment schedules, Lymphomun was applied (a) after allogeneic stem cell transplantation (allo-SCT, n = 6) to induce sustained long-term remission, or (b) stand alone prior to subsequent chemotherapy to eradicate residual disease before allo-SCT (n = 4). Nine of ten children displayed a clinical response: three stable diseases (SD), one partial remission (PR) and five induced or sustained complete remissions (CR). Five of these nine responders died during follow-up. The other patients still maintain CR with a current overall survival of 874-1424 days (median: 1150 days). In conclusion, despite the dismal clinical prognosis of children refractory to standard therapy, immunotherapy with Lymphomun resulted in a favourable clinical outcome in this cohort of refractory paediatric patients.

Overexpression of the epithelial cell adhesion molecule is associated with a more favorable prognosis and response to platinum-based chemotherapy in ovarian cancer.

OBJECTIVE: Epithelial cell adhesion molecule (EpCAM) has experienced a renaissance lately as a binding site for targeted therapy as well as a prognostic marker in epithelial malignancies. Aim of this study was to study EpCAM as a potential prognostic marker in epithelial ovarian cancer (EOC). METHODS: EpCAM expression was assessed by immunohistochemistry on paraffin-embedded primary EOC-tissue samples. EpCAM overexpression was defined as an expression of EpCAM of 76% to 100%. Tissue samples and clinical data were systematically collected within the international and multicenter "Tumorbank Ovarian Cancer" network. RESULTS: Seventy-four patients, diagnosed with EOC between 1994 and 2009, were included in the study (median age, 56 years; range, 31 to 86 years). The majority of the patients (81.1%) presented with an advanced stage International Federation of Gynecology and Obstetrics (FIGO) III/IV disease. Histology was of the serous type in 41 patients (55.4%), endometrioid in 19 (25.6%), and mucinous in 14 (19%). EpCAM was overexpressed in 87.7%. Serous tumors overexpressed EpCAM significantly more often than mucinous tumors (87.8% vs. 78.6%, p=0.045); while no significant difference was noted between the other histological subgroups. EpCAM overexpression was significantly associated with a better progression free survival and higher response rates to platinum based chemotherapy (p=0.040 and p=0.048, respectively). EpCAM was identified as an independent prognostic marker for overall survival (p=0.022). CONCLUSION: Our data indicate a significant association of EpCAM overexpression with a more favorable survival in EOC-patients. Serous cancers showed a significant EpCAM overexpression compared to mucinous types. Larger multicenter analyses are warranted to confirm these findings.

The role of relative lymphocyte count as a biomarker for the effect of catumaxomab on survival in malignant ascites patients: results from a phase II/III study.

PURPOSE: We report the role of relative lymphocyte count (RLC) as a potential biomarker with prognostic impact for catumaxomab efficacy and overall survival (OS) based on a post hoc analysis of the pivotal phase II/III study of intraperitoneal catumaxomab treatment of malignant ascites. EXPERIMENTAL DESIGN: The impact of treatment and RLC on OS was evaluated using multivariate Cox models. Kaplan-Meier and log-rank tests were used for group comparisons. Survival analyses were performed on the safety population [patients with paracentesis plus ≥ 1 dose of catumaxomab (n = 157) and paracentesis alone (n = 88)]. Determination of the optimal cutoff value for RLC was based on five optimality criteria. RESULTS: OS was significantly longer with catumaxomab versus paracentesis alone (P = 0.0219). The 6-month OS rate with catumaxomab was 28.9% versus 6.7% with paracentesis alone. RLC had a positive impact on OS and was an independent prognostic factor (P < 0.0001). In patients with RLC > 13% (n = 159: catumaxomab, 100 and control, 59), catumaxomab was associated with a favorable effect on OS versus paracentesis alone (P = 0.0072), with a median/mean OS benefit of 41/131 days and an increased 6-month survival rate of 37.0% versus 5.2%, respectively. In patients with RLC ≤ 13% at screening (n = 74: catumaxomab, 50 and control, 24), the median (mean) OS difference between the catumaxomab and the control group was 3 (16) days, respectively (P = 0.2561). CONCLUSIONS: OS was significantly improved after catumaxomab treatment in patients with malignant ascites. An RLC > 13% at baseline was a significant prognostic biomarker.

Expression of epithelial cell adhesion molecule in paired tumor samples of patients with primary and recurrent serous ovarian cancer.

OBJECTIVE: Ovarian cancer (OC) recurrence constitutes a therapeutic dilemma with various novel targeted agents emerging that offer alternative treatment options. The aim of the present study was to evaluate and compare epithelial cell adhesion molecule (EpCAM) expression profiles in paired tumor samples of patients with OC relapse. METHODS: EpCAM expression was analyzed by immunohistochemistry using the avidin-biotin-complex method on paraffin-embedded OC tissues obtained at primary surgery as well as on corresponding tumor samples of the same patients at relapse. The EpCAM overexpression was defined as 76% to 100% of tumor cells positively stained for EpCAM. Clinical data were collected within the Tumorbank Ovarian Cancer Network. RESULTS: Nineteen patients with serous OC histology were included in the study (median age at primary diagnosis, 50 years; range, 40-74 years). The majority of the patients (95%) presented with International Federation of Gynecology and Obstetrics stage III/IV, and 68.4% of the tumors were poorly differentiated. A complete macroscopic tumor resection could be achieved in 15 patients (78.9%) at diagnosis. Epithelial cell adhesion molecule overexpression was detected in 17 (89%) of the primary and 16 (84%) of the recurrent tumors (P = 1.0); hence, no significant change of the EpCAM expression profile could be identified over time. CONCLUSIONS: Epithelial cell adhesion molecule expression profile appears to remain stable during the course from the primary throughout the relapse of serous OC. The results indicate that EpCAM might be an interesting therapeutic target structure in serous OC.

Potential of the trifunctional bispecific antibody surek depends on dendritic cells: rationale for a new approach of tumor immunotherapy.

Trifunctional bispecific antibodies (trAbs) used in tumor immunotherapy have the unique ability to recruit T cells toward antigens on the tumor cell surface and, moreover, to activate accessory cells through their immunoglobulin Fc region interacting with activating Fcγ receptors. This scenario gives rise to additional costimulatory signals required for T cell-mediated tumor cell destruction and induction of an immunologic memory. Here we show in an in vitro system that most effective trAb-dependent T-cell activation and tumor cell elimination are achieved in the presence of dendritic cells (DCs). On the basis of these findings, we devise a novel approach of cancer immunotherapy that combines the specific advantages of trAbs with those of DC-based vaccination. Simultaneous delivery of trAbs and in vitro differentiated DCs resulted in a markedly improved tumor rejection in a murine melanoma model compared with monotherapy.

Ganglioside GD2-specific trifunctional surrogate antibody Surek demonstrates therapeutic activity in a mouse melanoma model.

BACKGROUND: Trifunctional bispecific antibodies (trAb) are a special class of bispecific molecules recruiting and activating T cells and accessory immune cells simultaneously at the targeted tumor. The new trAb Ektomab that targets the melanoma-associated ganglioside antigen GD2 and the signaling molecule human CD3 (hCD3) on T cells demonstrated potent T-cell activation and tumor cell destruction in vitro. However, the relatively low affinity for the GD2 antigen raised the question of its therapeutic capability. To further evaluate its efficacy in vivo it was necessary to establish a mouse model. METHODS: We generated the surrogate trAb Surek, which possesses the identical anti-GD2 binding arm as Ektomab, but targets mouse CD3 (mCD3) instead of hCD3, and evaluated its chemical and functional quality as a therapeutic antibody homologue. The therapeutic and immunizing potential of Surek was investigated using B78-D14, a B16 melanoma transfected with GD2 and GD3 synthases and showing strong GD2 surface expression. The induction of tumor-associated and autoreactive antibodies was evaluated. RESULTS: Despite its low affinity of approximately 10(7) M(-1) for GD2, Surek exerted efficient tumor cell destruction in vitro at an EC(50) of 70 ng/ml [0.47 nM]. Furthermore, Surek showed strong therapeutic efficacy in a dose-dependent manner and is superior to the parental GD2 mono-specific antibody, while the use of a control trAb with irrelevant target specificity had no effect. The therapeutic activity of Surek was strictly dependent on CD4(+) and CD8(+) T cells, and cured mice developed a long-term memory response against a second challenge even with GD2-negative B16 melanoma cells. Moreover, tumor protection was associated with humoral immune responses dominated by IgG2a and IgG3 tumor-reactive antibodies indicating a Th1-biased immune response. Autoreactive antibodies against the GD2 target antigen were not induced. CONCLUSION: Our data suggest that Surek revealed strong tumor elimination and anti-tumor immunization capabilities. The results warrant further clinical development of the human therapeutic equivalent antibody Ektomab.

Trifunctional bispecific antibodies induce tumor-specific T cells and elicit a vaccination effect.

A major goal of tumor immunotherapy is the induction of long-lasting systemic T-cell immunity. Bispecific antibodies (bsAbs) that lack the immunoglobulin Fc region confer T-cell-mediated killing of tumor cells but do not induce long-term memory. In contrast, trifunctional bsAbs comprise an appropriate Fc region and, therefore, not only recruit T cells but also accessory cells that bear activating Fcγ receptors (FcγR), providing additional T-cell-activating signals and securing presentation of tumor-derived antigens to T cells. In this study, we show that trifunctional bsAbs induce a polyvalent T-cell response and, therefore, a vaccination effect. Mice were treated with melanoma cells and with a trifunctional bsAb directed against the melanoma target antigen ganglioside GD2 in addition to murine CD3. The trifunctional bsAb activated dendritic cells and induced a systemic immune response that was not replicated by treatment with the F(ab')2-counterpart lacking the Fc region. Restimulation of spleen and lymph node cells in vitro yielded T-cell lines that specifically produced interferon-γ in response to tumor. In addition, trifunctional bsAb-induced T cells recognized various specific peptides derived from melanoma-associated antigens. Moreover, these polyvalent responses proved to be tumor-suppressive and could not be induced by the corresponding bsF(ab')2-fragment. Taken together, our findings provide preclinical proof of concept that trifunctional bsAbs can induce tumor-specific T cells with defined antigen specificity.

First patient treated with a re-challenge of catumaxomab in recurrent malignant ascites: a case report.

In the past, treatment for malignant ascites focussed on symptomatic relief or treatment of the underlying disease. A promising option evolved with catumaxomab (Removab(®)) in 2009. Since catumaxomab is a bispecific, trifunctional antibody with mouse-rat origin, so far repeated treatment cycles were not an option due to the occurrence of human anti-drug antibodies (HADA). Nevertheless, the good results obtained so far raised the question whether a repeated treatment cycle with catumaxomab could be feasible and effective. We report on a 74-year-old female patient with breast cancer and peritoneal carcinomatosis. To our knowledge, this is the first patient world-wide to be treated with a repeated cycle of catumaxomab. HAMA (human anti-mouse antibodies) values were identified in blood and ascites samples. Ascites samples were also stained to identify and quantify cells, positive for EpCAM (epithelial cell adhesion molecule) and CD45. The patient tolerated the second cycle without unexpected side effects and remained puncture-free for another 45 days. Analysis of blood and ascites revealed a quick increase in HAMA values in the blood samples after 1 week, but considerably lower HAMA values and delayed increase in the ascites samples. Also a distinct and continuous decrease of EpCAM-positive cells was observed in the ascites samples under treatment. A strong increase in CD45-positive cells was detected after the beginning of the second cycle, with a consecutive decline toward the end. This first experience suggests that a repeated cycle of catumaxomab might be feasible and effective. As a consequence, a phase II trial (SECIMAS) was initiated.

Cancer therapy with trifunctional antibodies: linking innate and adaptive immunity.

Trifunctional antibodies (trAbs) are promising novel anticancer biologics with a particular mode of action capable of linking innate with adaptive immunity. Based on their unique structure, trifunctional IgG-like heterodimeric antibodies, consisting of nonhuman mouse and rat immunoglobulin halves are able to redirect T lymphocytes, as well as accessory cells, to the tumor site. This recruitment of immune cells is accompanied by cellular activation events elicited by anti-CD3, as well as Fcγ-receptor engagement of trAbs supported by a proinflammatory Th1-biased cytokine milieu. All necessary immunological factors required for long-term vaccination-like effects are stimulated along trAb-mediated therapeutic interventions. Thus, the concerted interplay of antibody-dependent cellular cytotoxicity plus the polyclonal T-cell cytotoxicity and Fcγ-receptor-driven induction of long-lasting immune responses after the initial tumor cell elimination represent the major hallmarks of trAb-mediated treatment of malignant diseases.

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.

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

Patients with malignant ascites secondary to primary carcinomas benefit from intraperitoneal therapy with the trifunctional antibody catumaxomab (anti-EpCAM × anti-CD3). Here, we report the analysis of peritoneal fluid samples from 258 patients with malignant ascites randomized to catumaxomab or control groups to investigate the molecular effects of catumaxomab treatment. In the catumaxomab group, tumor cell numbers and peritoneal levels of VEGF decreased, whereas the activation status of CD4(+) and CD8(+) T-cell populations increased more than two-fold after treatment. Notably, CD133(+)/EpCAM(+) cancer stem cells vanished from the catumaxomab samples but not from the control samples. In vitro investigations indicated that catumaxomab eliminated tumor cells in a manner associated with release of proinflammatory Th1 cytokines. Together, our findings show that catumaxomab therapy activates peritoneal T cells and eliminates EpCAM(+) tumor cells, establishing a molecular and cellular basis to understand in vivo efficacy within the immunosuppressed malignant ascites tissue microenvironment.

Immunotherapy of peritoneal carcinomatosis with the antibody catumaxomab in colon, gastric, or pancreatic cancer: an open-label, multicenter, phase I/II trial.

BACKGROUND: Peritoneal carcinomatosis (PC) is common in gastrointestinal (GI) cancer and there is no effective standard treatment. We investigated the tolerability and maximum tolerated dose (MTD) of the trifunctional antibody catumaxomab in patients with PC. METHODS: In this open-label, phase I/II clinical trial, patients with epithelial cell adhesion molecule (EpCAM)-positive PC from GI cancer received 4 sequential intraperitoneal catumaxomab infusions: day 0: 10 µg; day 3: 10 or 20 µg; day 7: 30, 50, or 100 µg; and day 10: 50, 100, or 200 µg. Dose escalation was guided by dose-limiting toxicities. RESULTS: The MTD was 10, 20, 50, and 200 µg on days 0, 3, 7, and 10, respectively. Catumaxomab had an acceptable safety profile: Most common treatment-related adverse events (at the MTD) were fever, vomiting, and abdominal pain. At final examination, 11/17 evaluable patients (65%) were progression free: 1 patient had a complete and 3 a partial response. Median overall survival from the time of diagnosis of PC was 502 days. CONCLUSIONS: Intraperitoneal catumaxomab is a promising option for the treatment of PC from GI cancer.