Activity and safety of afatinib in a window preoperative EORTC study in patients with squamous cell carcinoma of the head and neck (SCCHN).

Background: To investigate the activity and safety of afatinib in the preoperative treatment of squamous cell carcinoma of the head and neck (SCCHN). Patients and methods: This study was an open-label, randomized, multicenter, phase II window of opportunity trial. Treatment-naïve SCCHN patients selected for primary curative surgery were randomized (5 : 1 ratio) to receive afatinib during 14 days (day -15 until day -1) before surgery (day 0) or no treatment. Tumor biopsies, 2-[fluorine-18]-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET), and magnetic resonance imaging (MRI) were carried out at diagnosis and just before surgery. The primary end point was metabolic FDG-PET response (according to EORTC guidelines). Other end points included response assessment based on the Response Evaluation Criteria In Solid Tumors (RECIST) v1.1, dynamic contrast-enhanced (DCE)-MRI, diffusion weighted (DW)-MRI, safety, and translational research (TR). Results: Thirty patients were randomized: 25 to afatinib and 5 to control arm. Of the 23 eligible patients randomized to afatinib, 16 (70%; 95% CI: 47% to 87%) patients had a partial metabolic FDG-PET response (PMR). Five patients (22%; 95% CI: 8% to 44%) showed a partial response by RECISTv1.1. Responses assessed via DCE-MRI and DWI-MRI did not show a strong association with PMR or RECIST. One patient discontinued afatinib after 11 days for grade 3 diarrhea with subsequent renal failure and 24 days delay in surgery. No grade 4 toxicities or surgical comorbidities related to afatinib were reported. TR results indicated that PMR was more frequent in the tumors with high Cluster3-hypoxia score expression and with TP53 wild type. Conclusion: Afatinib given for 2 weeks to newly diagnosed SCCHN patients induces a high rate of FDG-PET partial metabolic response and partial response according to RECISTv1.1. Afatinib can be safely administered before surgery. Although exploratory, the hypoxic gene signature needs further investigations as a predictive biomarker of afatinib activity. Clinical trial registration: ClinicalTrials.gov: NCT01538381.

An immunologically relevant rodent model demonstrates safety of therapy using a tumour-specific IgE.

BACKGROUND: Designing biologically informative models for assessing the safety of novel agents, especially for cancer immunotherapy, carries substantial challenges. The choice of an in vivo system for studies on IgE antibodies represents a major impediment to their clinical translation, especially with respect to class-specific immunological functions and safety. Fcε receptor expression and structure are different in humans and mice, so that the murine system is not informative when studying human IgE biology. By contrast, FcεRI expression and cellular distribution in rats mirror that of humans. METHODS: We are developing MOv18 IgE, a human chimeric antibody recognizing the tumour-associated antigen folate receptor alpha. We created an immunologically congruent surrogate rat model likely to recapitulate human IgE-FcεR interactions and engineered a surrogate rat IgE equivalent to MOv18. Employing this model, we examined in vivo safety and efficacy of antitumour IgE antibodies. RESULTS: In immunocompetent rats, rodent IgE restricted growth of syngeneic tumours in the absence of clinical, histopathological or metabolic signs associated with obvious toxicity. No physiological or immunological evidence of a "cytokine storm" or allergic response was seen, even at 50 mg/kg weekly doses. IgE treatment was associated with elevated serum concentrations of TNFα, a mediator previously linked with IgE-mediated antitumour and antiparasitic functions, alongside evidence of substantially elevated tumoural immune cell infiltration and immunological pathway activation in tumour-bearing lungs. CONCLUSION: Our findings indicate safety of MOv18 IgE, in conjunction with efficacy and immune activation, supporting the translation of this therapeutic approach to the clinical arena.

Targeting the folate receptor: diagnostic and therapeutic approaches to personalize cancer treatments.

BACKGROUND: In cancer therapy, molecularly targeted agents have the potential to maximize antitumor efficacy while minimizing treatment-related toxicity. However, these agents may only be effective in specific tumor subtypes with defined genomic profiles. This emphasizes the importance of developing personalized cancer therapeutic strategies (i.e. through the use of companion diagnostic tests) to appropriately select and treat patients who are likely to benefit from specific targeted therapies, thus leading to improvements in clinical and safety outcomes. A potential biological target is the folate receptor (FR), which has been shown to be overexpressed on the surface of many cancers, including tumors of the lungs and ovaries. DESIGN: We carried out a literature search to identify how the FR can be a potential target for selected tumors, and how the FR expression can be exploited by targeted therapies. RESULTS: The two main therapeutic strategies for targeting the FR are based on the use of: (i) an anti-FR antibody (e.g. farletuzumab) and (ii) folate conjugates of folate-targeted chemotherapies and companion radiodiagnostic imaging agents (e.g. vintafolide and (99m)technetium-etarfolatide). Both of these strategies are being assessed in phase III trials. CONCLUSIONS: The important role that the FR plays in cancer development and progression has led to the development of FR-targeted therapeutic approaches. To date, the promising data observed in phase II clinical trials have not been confirmed in phase III studies. Accordingly, there is a need for further research in the refinement of patient selection and identification of new therapeutic combinations. In particular, the development of these targeted therapies requires reliable methods to be developed to detect FR-positive tumors in order to help select patients who may benefit from treatment.

Choline kinase-alpha by regulating cell aggressiveness and drug sensitivity is a potential druggable target for ovarian cancer.

BACKGROUND: Aberrant choline metabolism has been proposed as a novel cancer hallmark. We recently showed that epithelial ovarian cancer (EOC) possesses an altered MRS-choline profile, characterised by increased phosphocholine (PCho) content to which mainly contribute over-expression and activation of choline kinase-alpha (ChoK-alpha). METHODS: To assess its biological relevance, ChoK-alpha expression was downmodulated by transient RNA interference in EOC in vitro models. Gene expression profiling by microarray analysis and functional analysis was performed to identify the pathway/functions perturbed in ChoK-alpha-silenced cells, then validated by in vitro experiments. RESULTS: In silenced cells, compared with control, we observed: (I) a significant reduction of both CHKA transcript and ChoK-alpha protein expression; (II) a dramatic, proportional drop in PCho content ranging from 60 to 71%, as revealed by (1)H-magnetic spectroscopy analysis; (III) a 35-36% of cell growth inhibition, with no evidences of apoptosis or modification of the main cellular survival signalling pathways; (IV) 476 differentially expressed genes, including genes related to lipid metabolism. Ingenuity pathway analysis identified cellular functions related to cell death and cellular proliferation and movement as the most perturbed. Accordingly, CHKA-silenced cells displayed a significant delay in wound repair, a reduced migration and invasion capability were also observed. Furthermore, although CHKA silencing did not directly induce cell death, a significant increase of sensitivity to platinum, paclitaxel and doxorubicin was observed even in a drug-resistant context. CONCLUSION: We showed for the first time in EOC that CHKA downregulation significantly decreased the aggressive EOC cell behaviour also affecting cells' sensitivity to drug treatment. These observations open the way to further analysis for ChoK-alpha validation as a new EOC therapeutic target to be used alone or in combination with conventional drugs.

Monitoring response to cytostatic cisplatin in a HER2(+) ovary cancer model by MRI and in vitro and in vivo MR spectroscopy.

BACKGROUND: Limited knowledge is available on alterations induced by cytostatic drugs on magnetic resonance spectroscopy (MRS) and imaging (MRI) parameters of human cancers, in absence of apoptosis or cytotoxicity. We here investigated the effects of a cytostatic cisplatin (CDDP) treatment on (1)H MRS and MRI of HER2-overexpressing epithelial ovarian cancer (EOC) cells and in vivo xenografts. METHODS: High-resolution MRS analyses were performed on in vivo passaged SKOV3.ip cells and cell/tissue extracts (16.4 or 9.4 T). In vivo MRI/MRS quantitative analyses (4.7 T) were conducted on xenografts obtained by subcutaneous implantation of SKOV3.ip cells in SCID mice. The apparent diffusion coefficient (ADC) and metabolite levels were measured. RESULTS: CDDP-induced cytostatic effects were associated with a metabolic shift of cancer cells towards accumulation of MRS-detected neutral lipids, whereas the total choline profile failed to be perturbed in both cultured cells and xenografts. In vivo MRI examinations showed delayed tumour growth in the CDDP-treated group, associated with early reduction of the ADC mean value. CONCLUSION: This study provides an integrated set of information on cancer metabolism and physiology for monitoring the response of an EOC model to a cytostatic chemotherapy, as a basis for improving the interpretation of non-invasive MR examinations of EOC patients.

Comprehensive gene expression meta-analysis of head and neck squamous cell carcinoma microarray data defines a robust survival predictor.

BACKGROUND: Head and neck squamous cell carcinoma refers to a heterogeneous disease frequently aggressive in its biologic behavior. Despite the improvements in the therapeutic modalities, the long-term survival rate remained unchanged over the past decade and patients with this type of cancer are at a high risk of developing recurrence. For this reason, there is a great need to find better ways to foresee outcome, to improve treatment choices, and to enable a more personalized approach. PATIENTS AND METHODS: Nine microarray gene expression datasets, reporting survival data of a total of 841 samples, were retrieved from publicly repositories. Three datasets, profiled on the same version of microarray chips, were selected and merged following a meta-analysis approach to build a training set. The remaining six studies were used as independent validation sets. RESULTS: The training set led us to identify a 172-gene signature able to stratify patients in low or high risk of relapse [log-rank, P = 2.44e-05; hazard ratio (HR) = 2.44, 95% confidence interval (CI) 1.58-3.76]. The model based on the 172 genes was validated on the six independent datasets. The performance of the model was challenged against other proposed prognostic signatures (radiosensitivity index, 13-gene oral squamous cell carcinoma signature, hypoxia metagene, 42-gene high-risk signature) and was compared with a human papillomavirus (HPV) signature: our model resulted independent and even better in prediction. CONCLUSIONS: We have identified and validated a prognostic model based on the expression of 172 genes, independent from HPV status and able to improve assessment of patient's risk of relapse compared with other molecular signatures. In order to transpose our model into a useful clinical grade assay, additional work is needed following the framework established by the Institute of Medicine and REMARK guidelines.

Harnessing engineered antibodies of the IgE class to combat malignancy: initial assessment of FcɛRI-mediated basophil activation by a tumour-specific IgE antibody to evaluate the risk of type I hypersensitivity.

BACKGROUND: IgE antibodies, sequestered into tissues and retained locally by the high-affinity IgE receptor, FcɛRI, on powerful effector cells such as mast cells, macrophages and eosinophils, may offer improvements in the therapy of solid tumours. The chimeric antibody, MOv18 IgE, against the human ovarian carcinoma antigen, folate receptor α (FRα), is more effective than its IgG1 counterpart in xenograft models of ovarian cancer. Although MOv18 IgE binds to a single epitope on FRα and cannot cross-link IgE receptors on basophils, there remains a risk that components in the circulation of ovarian cancer patients might cross-link FRα-MOv18-IgE-receptor-FcɛRI complexes on basophils to cause type I hypersensitivity. OBJECTIVE: To assess the propensity for MOv18 used in a therapeutic setting to cause FcɛRI-mediated type I hypersensitivity. METHODS: As validated readouts of the potential for MOv18 to cause FcɛRI-mediated type I hypersensitivity we measured release of a granule-stored mediator from a rat basophilic leukaemia cell line RBL SX-38 stably transfected with human tetrameric (αßγ2) FcɛRI, and induction of CD63 on blood basophils from patients with ovarian carcinoma and healthy controls ex vivo. RESULTS: Serum FRα levels were increased in ovarian cancer patients compared with healthy controls. MOv18 IgE alone, or in the presence of its antigen recombinant human FRα, or of healthy volunteer (n=14) or ovarian carcinoma patient (n=32) sera, did not induce RBL SX-38 cell degranulation. Exposure to FRα-expressing ovarian tumour cells at target-to-effector ratios expected within tumours induced degranulation. MOv18 IgE did not induce expression of CD63 in blood basophils from either healthy volunteers (n=6), or cancer patients, despite detectable levels of circulating FRα (n=5). CONCLUSION AND CLINICAL RELEVANCE: These encouraging data are compatible with the hypothesis that, when ovarian carcinoma patients are treated with MOv18, FcɛRI-mediated activation of effector cells occurs within the tumour mass but not in the circulation mandating, with due caution, further pre-clinical studies.

Anti-PSMA 124I-scFvD2B as a new immuno-PET tool for prostate cancer: preclinical proof of principle.

BACKGROUND: Prostate cancer (PCa) is the second leading cause of cancer-related death in the Western population. The use in oncology of positron emission tomography/computed tomography (PET/CT) with emerging radiopharmaceuticals promises accurate staging of primary disease, restaging of recurrent disease and detection of metastatic lesions. Prostate-specific membrane antigen (PSMA) expression, directly related to androgen-independence, metastasis and progression, renders this tumour associate antigen a good target for the development of new radiopharmaceuticals for PET. Aim of this study was to demonstrate in a preclinical in vivo model (PSMA-positive versus PSMA-negative tumours) the targeting specificity and sensitivity of the anti-PSMA single-chain variable fragment (scFv) labelled with 124I. METHODS: The 124I-labeling conditions of the antibody fragment scFvD2B were optimized and assessed for purity and immunoreactivity. The specificity of 124I-scFvD2B was tested in mice bearing PSMA-positive and PSMA-negative tumours to assess both ex-vivo biodistribution and immune-PET. RESULTS: The uptake fraction of 124I-scFvD2B was very high on PSMA positive cells (range 75-91%) and highly specific and immuno-PET at the optimal time point, defined between 15 h and 24 h, provides a specific localization of lesions bearing the target antigen of interest (PSMA positive vs PSMA negative tumors %ID/g: p = 0.0198 and p = 0.0176 respectively) yielding a median target/background ratio around 30-40. CONCLUSIONS: Preclinical in vivo results of our immuno-PET reagent are highly promising. The target to background ratio is improved notably using PET compared to SPECT previously performed. These data suggest that, upon clinical confirmation of sensitivity and specificity, our anti-PSMA 124I-scFvD2B may be superior to other diagnostic modalities for PCa. The possibility to combine in patients our 124I-scFvD2B in multi-modal systems, such as PET/CT, PET/MR and PET/SPECT/CT, will provide quantitative 3D tomographic images improving the knowledge of cancer biology and treatment.

Cellular immune reaction to human malignant melanoma and breast carcinoma cells.

An in vitro microassay was used to study cytotoxic reactivity of lymphocytes of 19 patients with malignant melanoma, 8 patients with breast carcinoma, and 18 normal subjects on cell cultures of malignant melanoma and breast carcinoma. In each of the twelve experiments, peripheral blood lymphocytes from individuals with and without cancer were tested simultaneously on two or three different target cells. Cytotoxic reactivity, evaluated by a comparison of the number of target cells remaining after incubation with lymphocytes with those incubated with medium only, was found in 20 cancer patients (74%) and 13 individuals without cancer (72%). The strength of lymphocyte reactivity of the cancer and of the non-cancer group did not differ significantly. Of the 27 cancer patients, 8 were positive only on the homologous target cells, 7 only on the opposite cells, and 5 on both types; 7 were negative. Short-term melanoma cell cultures were more lysable than were established cell lines; however, no direct correlation between the growth rate during the test period and susceptibility to lysis was seen. The blood group of the lymphocyte donors had no influence on cytotoxic reactivity.

Human renal antigen defined by a murine monoclonal antibody.

Fusion of spleen cells from a mouse immunized with a surgical specimen of a human renal carcinoma with murine P3 myeloma cells resulted in the establishment of a hybridoma cell line that secreted a monoclonal antibody (MKi-1), of IgG1 subclass, which preferentially reacted on kidney crude membrane (CM) preparations. This monoclonal antibody was tested by solid-phase radioimmunometric assay and immunofluorescence (IF) on a panel of tumor cell lines and on CM preparations and cell suspensions from surgical specimens of normal and neoplastic tissues. In addition, cryosections of normal and cancer tissues of various histologic types were tested by IF. The expression of the MKi-1 antigen was limited to normal kidney epithelium, renal cancers, some areas in the pancreas, the apical region of some breast ducts, and a proportion (5-50%) of activated lymphocytes. Electron microscopic study by the immunoperoxidase technique on fixed sections from normal kidney showed that MKi-1 stained the brush border of almost all proximal tubules. The molecule recognized by MKi-1 was a single polypeptide chain with a molecular weight of 140,000.

Ricin A chain conjugated with monoclonal antibodies selectively killing human carcinoma cells in vitro.

Ricin A chain was coupled to murine monoclonal antibodies MBr1 and MOv2 respectively raised against human breast and ovarian carcinomas. Inhibition of protein synthesis only occurred in those cultured human tumor cells bearing the appropriate target antigens, demonstrating that both components of the conjugate were unchanged in regards to specificity and toxicity. Conjugates were 125-200 times more efficient in inhibiting [3H]proline incorporation than the uncoupled ricin A chain. They were however unable to kill the entire population of the appropriate cells even after repeated treatment. Although the two monoclonal antibodies had similar binding kinetics, the conjugates differed in their cytotoxicity kinetics. The MBr1-ricin A chain conjugate had slow kinetics, and about 20 hours were needed to obtain a protein synthesis inhibition above 50% on the appropriate line (mammary carcinoma MCF-7). In contrast, the MOv2-ricin A chain conjugate showed very fast kinetics, reaching 50% inhibition after only 30 minutes of treatment on both appropriate cell lines SW626 and HT-29 from ovarian and colon carcinomas, respectively. Growth conditions of cell lines, i.e., adherent cells versus suspended cells, and plating time were found to greatly influence the conjugates' killing efficiencies. These studies confirm the possibility of preparing ricin A chain-antibody conjugates, which retain specific cytotoxicity against tumor cells; but they also underline the need for further in vitro studies of various parameters before one considers a therapeutic use of such conjugates.

Regression of advanced ovarian carcinoma by intraperitoneal treatment with autologous T lymphocytes retargeted by a bispecific monoclonal antibody.

BACKGROUND: The high frequency of relapse after induction chemotherapy of advanced ovarian carcinoma calls for new therapeutic approaches. Lysis of ovarian carcinoma cells can be achieved by retargeting of T lymphocytes using F(ab')2 fragments of the bispecific monoclonal antibody (MAb) OC/TR, which is directed to the CD3 molecule on T lymphocytes and to the folate receptor on ovarian carcinoma cells. PURPOSE: Our purpose was to assess in ovarian carcinoma patients the antitumor activity of in vitro-activated autologous peripheral blood T lymphocytes retargeted with OC/TR. METHODS: Patients with epithelial ovarian cancer (International Federation of Gynecology and Obstetrics stages III and IV) meeting specific criteria were eligible to enter a phase II immunotherapy trial. Before immunotherapy, the 28 patients who entered the trial underwent laparotomy to reduce their tumor load and to allow measurement of all indicator lesions. They then received two cycles of five daily intraperitoneal infusions of autologous in vitro activated peripheral blood T lymphocytes retargeted with OC/TR plus recombinant interleukin 2 (IL-2) with (n = 11) or without (n = 17) a second daily infusion of OC/TR F(ab')2 and IL-2. Response to treatment could be assessed in 26 patients following explorative laparotomy; time to progression could be assessed in 27 patients. RESULTS: Seven patients had clinical evidence of progressive disease after treatment and therefore did not undergo laparotomy. Of the 19 patients evaluated by surgery and histology, three showed complete response, one showed complete intraperitoneal response with progressive disease in retroperitoneal lymph nodes, three showed partial response, seven had stable disease, and five had progressive disease. The overall intraperitoneal response rate was 27% (95% confidence interval [CI] = 10%-44%). The complete responses seen in three patients lasted 26 months in one patient, 23 months in the second, and 18 months in the third. Two patients were not assessable for response. One of these patients had bowel perforation during catheter removal, which precluded further evaluation. The second patient was positive only by cytologic examination before immunotherapy, was tumor free at laparotomy after immunotherapy, and remained so for the entire 21 months of follow-up, as determined by cytologic examination of random biopsy specimens. The median time to disease progression in the 15 assessable patients plus those who had stable disease was 11 months (95% CI = 6-18 months). Immunotherapy-related toxic effects included mild to moderate fever, nausea, emesis, and fatigue. Anti-mouse antibodies were detectable by the end of the treatment in 21 of 25 patients tested. CONCLUSIONS: Locoregional immunotherapy of ovarian cancer with bispecific MAb-retargeted T lymphocytes can result in tumor regression. Toxicity was mild to moderate and only transient. IMPLICATIONS: Improvement in systemic antitumor responses is needed before this approach can prove useful as adjunctive treatment following induction chemotherapy in patients with minimal residual disease.

Generation of monoclonal antibodies reacting with normal and cancer cells of human breast.

From the fusion of the murine myeloma P3- X63-Ag8-U1 with spleen cells from a mouse immunized with the human breast cancer cell line MCF-7, 88 hybridomas producing antibodies reacting with the immunizing cells were obtained. After a first screening on human leukocytes, red blood cells, and platelets and on human and fetal calf serum, three monoclonal antibodies, MBr1, MBr2, and MBr3, with specificity for the immunizing cells were isolated and further characterized. The three monoclonals were tested by isotopic antiglobulin assay and immunofluorescence on a panel of normal cells or cell membrane preparations, including milk epithelial and foam cells; on plasma and milk proteins; on cells or cell membrane preparations from fresh surgical specimens of breast, kidney, and ovarian carcinomas; and on various tumor cell lines. MBr1 and MBr2 had a superimposable reactivity and showed specificity for a structure which seems to characterize both normal and neoplastic mammary gland epithelial cells.

Immunochemical analysis of the determinant recognized by a monoclonal antibody (MBr1) which specifically binds to human mammary epithelial cells.

A monoclonal antibody (MBr1) raised against a membrane preparation (CM) of a human breast cancer line (MCF-7) and characterized as mammary gland epithelium associated (S. Mènard, E. Tagliabue, S. Canevari, G. Fossati, and M. I. Colnaghi. Generation of monoclonal antibodies reacting with normal and cancer cells of human breast. Cancer Res., 43:1295-1300, 1983), was used to biochemically define and partially purify its target antigen. The antigenic activity recognized by MBr1 was unaffected by treatment of MCF-7 cells with trypsin, protease K, or Vibrio cholerae neuraminidase and by heating at 100 degrees but was abolished by treatment with methanol. Since this behavior suggested a glycolipid nature of the MBr1-defined antigen, total lipids were obtained by chloroform:methanol or tetrahydrofuran:phosphate buffer extractions from crude membrane preparations of MCF-7 cells and of breast cancer surgical specimens. Total absorption of MBr1 activity was found by breast cancer lipid extracts, whereas no absorbing capability was detected with a series of highly purified acid and neutral glycolipids or with normal and neuraminidase-treated red blood cells of human, ox, and sheep species. The same pattern of inhibition of MBr1-binding activity was obtained with total lipid extract and both phases after diethyl ether partition. However, when the three extracts were chromatographed on diethylaminoethyl-Sepharose, the antigenic activity was recovered only in the neutral glycolipid fractions. Periodate oxidation of MCF-7 crude membrane preparation abolished MBr1-binding activity, suggesting that the carbohydrate portion of the molecule may constitute the antigenic determinant.

Gene transfection and expression of the ovarian carcinoma marker folate binding protein on NIH/3T3 cells increases cell growth in vitro and in vivo.

The glycoprotein gp38 is overexpressed in 90% of ovarian carcinomas and recognized by monoclonal antibodies MOv18 and MOv19. This molecule is a high affinity folate binding protein (FBP) and a potential marker for ovarian carcinoma. We have developed a model to investigate the biochemical and biological properties of this folate receptor by transfecting NIH/3T3 cells, which do not endogenously express FBP, with a vector containing the complementary DNA for the gp38 cloned from the ovarian carcinoma cell line IGROV1. The FBP expressed shows features identical to those of the protein produced by IGROV1 cell. The FBP is expressed on the cell membrane in a glycosylphosphatidylinositol-linked form, since it is released by treatment with phosphatidylinositol-specific phospholipase C, and is shed into the culture medium of the NIH/3T3 transfectants. Immunoblot analysis with MAbs MOv18 and MOv19 showed that both the glycosylphosphatidylinositol-linked and the soluble FBP migrate at the same apparent molecular weight as the respective IGROV1 proteins. The FBP-transfected NIH/3T3 cells bound folic acid and internalized about 30-fold more folic acid than mock-transfected cells. Growth analysis revealed that FBP-transfected NIH/3T3 cells like IGROV1 maintained their growth rate after 10 days of culture in medium containing physiological or low folate concentration, and tumors arising after transplanting FBP-tNIH/3T3 cells in nude mice were 3-fold heavier than those arising after transplantation of non-FBP-expressing NIH/3T3 cells. These results suggest a correlation between human ovarian carcinoma growth and FBP overexpression.

CD3-CD28 costimulation as a means to avoiding T cell preactivation in bispecific monoclonal antibody-based treatment of ovarian carcinoma.

One of the major limitations to the immunotherapy of ovarian carcinoma based on the use of anti-CD3/antitumor bispecific monoclonal antibodies (bi-mAb) is the need for preactivation of effector cells ex vivo, because cross-linking of the T cell receptor-CD3 complex per se may lead to T-cell unresponsiveness or even apoptosis. The bi-mAb OC/TR, which recognizes the folate-binding protein (FBP) overexpressed in 90% of ovarian carcinomas and the CD3 molecule on T cells, has demonstrated efficacy in a clinical setting. Here we investigated the possibility of delivering accessory signals to OC/TR-retargeted peripheral blood mononuclear cells (PBMCs) via an anti-CD28 mAb or an anti-FBP/anti-CD28 bi-mAb. Coculture of resting PBMCs from healthy donors with OC/TR, anti-FBP/anti-CD28 bi-mAb, and FBP+ tumor cell lines resulted in a highly activated phenotype of effector cells and in a dramatic in vitro growth inhibition of the target cells without an increase in OC/TR-redirected lysis. Whereas both the CD4 and CD8 T cell subsets were involved in the growth inhibition, only the CD8 subpopulation accounted for the cytotoxic activity. The in vitro tumor growth inhibition was mediated mainly by soluble factors, which were active on both FBP+ and FBP- ("bystander effect") cell lines. Activation and antitumor activity were also observed, albeit to a lesser extent, using OC/TR and monospecific bivalent anti-CD28 mAb. In vitro analysis demonstrated that cross-linking between tumor and effector cells for at least 24 h was needed to achieve T-cell activation and development of antitumor activities. Thus, ex vivo CD3-CD28 costimulation on resting PBMCs might be of therapeutic utility for local treatment of minimal residual disease.

Biochemical analysis of human ovarian cancer-associated antigens defined by murine monoclonal antibodies.

Two monoclonal antibodies (MOv1 and MOv2) raised against a membrane preparation of a human surgical specimen from a mucinous ovarian cystoadenocarcinoma were used to biochemically define their target antigens. The heating of peritumoral mucus-soluble extracts and the sialidase treatment of crude membrane preparations did not affect the binding capacity of MOv1 and MOv2, which, on the contrary, was significantly reduced by periodate oxidation of the same materials. Pronase digestion completely solubilized MOv1-defined antigens, whereas MOv2-defined antigens were only partially solubilized. This, however, did not affect antibody binding with digested products. These data suggest that carbohydrate residues of recognized molecules constitute the antigenic determinants and that sialic acid residues are not involved. Gel filtration on Sepharose 4B of the peritumoral mucus, solubilized either by 200 mM NaCl or Pronase, revealed that most of the antigenic activity eluted in the void-volume fractions with a high carbohydrate content and in the included fractions before the elution volume of the ferritin standard protein. When CsCl gradient equilibrium ultracentrifugation of the solubilized mucus was used, MOv1-recognized antigens sedimented with a density of 1.45 g/ml, while the MOv2-defined epitope was carried by molecules with a density of 1.52 g/ml as well as by molecules with a lower density. Using thin-layer chromatography of organic solvent extracts obtained from mucus and crude membrane preparations, only MOv2-positive molecules could be resolved as a single band of glycolipid. Altogether, these data suggest that the antigens detected by MOv1 are mainly mucins whereas the determinant recognized by MOv2 is carried by both mucins and a glycolipid. To analyze the diagnostic potential of MOv1- and MOv2-recognized molecules, we tested their presence, as soluble products, in supernatants of tumor cell lines and in peritoneal effusions from cancer patients. To this aim, we developed an immunoradiometric assay using the same monoclonal antibody in insolubilized and soluble form. Whereas MOv1-immunoradiometric assay was always negative, by MOv2-immunoradiometric assay it was possible to detect the relevant antigen in 8 of the 10 effusions from patients with well-differentiated ovarian tumors and in 5 of the 11 effusions from patients with poorly differentiated ovarian tumors, whereas the 10 control effusions from patients with various diseases were negative.

Panning phage antibody libraries on cells: isolation of human Fab fragments against ovarian carcinoma using guided selection.

The display of repertoires of human antibody (Ab) fragments on filamentous phages and selection by binding of the phage to antigen (Ag) have provided a ready means of deriving human Ab against purified Ag. However, it has been more difficult to obtain phage Ab against an individual Ag of a complex mixture, such as cell surface Ag. Using the technique of "guided selection," we generated human Ab against the high-affinity folate-binding protein (FBP), a cell surface Ag that is overexpressed in many human ovarian carcinomas. The guiding Ab template was provided by the light chain of mouse monoclonal Ab Mov19 (K[aff], 10[8] M[-1]) directed against FBP; this was paired with repertoires of human heavy chains displayed on phages, and the hybrid Ab fragments were selected by binding to an ovarian carcinoma cell line (OVCAR3). The selected human heavy chains were then paired with repertoires of human light chains. Further panning led to the isolation of a human Fab fragment, C4, with a binding affinity of 0.2 x 10(8) M(-1). This was highly specific for FBP, as demonstrated by ELISA and flow cytometry data and by immunoprecipitation of the relevant molecule from the cell surface of ovarian carcinoma cells. Moreover, C4 targeted the same or a closely related epitope of the Ag, as did the template rodent monoclonal Ab Mov19. These results suggest the usefulness of guided selection as a simple means to deriving human Ab against cell surface Ag for which a rodent Ab is available.

IgG2a induced by interleukin (IL) 12-producing tumor cell vaccines but not IgG1 induced by IL-4 vaccine is associated with the eradication of experimental metastases.

We evaluated whether antibody response correlates with tumor therapy by cytokine gene-modified tumor cell vaccines. To characterize the antibody (Ab) response against a known antigen, colon carcinoma C26 cells and C26 variants engineered to produce interleukin (IL) 12 or IL-4 were further transduced to express the human tumor-associated antigen gp38 folate receptor (FR) alpha. Irradiated IL-12- and IL-4-producing C26/FR alpha cell vaccines cured 50 and 30% of mice bearing C26/FR alpha lung micrometastases. Treatment induced a rapid, CD4-dependent Ab production dominated by IgG2a and IgG1 in response to the IL-12 or IL-4 vaccine, respectively. In contrast, untreated tumor-bearing mice showed a late serological response dominated by IgM. Anti-FR alpha IgG1 and IgG2a were able to suppress tumor metastases upon passive transfer in vivo. Sera from mice cured by the IL-12 vaccine displayed a higher binding activity, a higher anti-FR alpha IgG2a content, and a higher complement-mediated tumor cell lysis in vitro compared to the sera from nonresponder mice. Such a correlation was not found in the sera of mice treated with the IL-4 vaccine. These data indicate that cytokine-producing tumor cell vaccines strongly influence antibody response, and that in the case of the IL-12-based vaccine, the Ab titer correlates with the therapeutic response, thus suggesting its use for monitoring the outcome of vaccination in cancer patients.

Selective localization of matrix metalloproteinase 9, beta1 integrins, and human lymphocyte antigen class I molecules on membrane vesicles shed by 8701-BC breast carcinoma cells.

The shedding of membrane vesicles from the cell surface is a vital process considered to be involved in cell-cell and cell-matrix interactions and in tumor progression. By immunoelectron microscopic analysis of surface replicas of 8701-BC human breast carcinoma cells, we observed that membrane vesicles shed from plasma membranes contained densely clustered gelatinase B [matrix metalloproteinase 9 (MMP-9)], beta1 integrins, and human lymphocyte antigen class I molecules. By contrast, alpha-folate receptor was uniformly distributed on the smooth cell membrane and shedding areas. Both cell surface clustering of selected molecules and membrane vesicle release were evident only when cells were cultured in the presence of serum. Vesicle shedding occurred preferentially at the edge or along narrow protrusions of the cell. Specific accumulation of proMMP-9 and active forms of MMP-9 in shed vesicles was also demonstrated by gelatin zymography. In addition, Western blotting analysis showed the presence of a large amount of proMMP-9/tissue inhibitor of metalloproteinase 1 complex. The release of selected areas of plasma membranes enriched with MMP-9 and beta1 integrins indicates that membrane vesicle shedding from tumor cells plays an important role in the directional proteolysis of the extracellular matrix during cellular migration. The presence of human lymphocyte antigen class I antigens suggests a mechanism for tumor cells to escape from immune surveillance.