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.

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.

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.

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.

Synergistic anti-tumor activity and inhibition of angiogenesis by cotargeting of oncogenic and death receptor pathways in human melanoma.

Improving treatment of advanced melanoma may require the development of effective strategies to overcome resistance to different anti-tumor agents and to counteract relevant pro-tumoral mechanisms in the microenvironment. Here we provide preclinical evidence that these goals can be achieved in most melanomas, by co-targeting of oncogenic and death receptor pathways, and independently of their BRAF, NRAS, p53 and PTEN status. In 49 melanoma cell lines, we found independent susceptibility profiles for response to the MEK1/2 inhibitor AZD6244, the PI3K/mTOR inhibitor BEZ235 and the death receptor ligand TRAIL, supporting the rationale for their association. Drug interaction analysis indicated that a strong synergistic anti-tumor activity could be achieved by the three agents and the AZD6244-TRAIL association on 20/21 melanomas, including cell lines resistant to the inhibitors or to TRAIL. Mechanistically, synergy was explained by enhanced induction of caspase-dependent apoptosis, mitochondrial depolarization and modulation of key regulators of extrinsic and intrinsic cell death pathways, including c-FLIP, BIM, BAX, clusterin, Mcl-1 and several IAP family members. Moreover, silencing experiments confirmed the central role of Apollon downmodulation in promoting the apoptotic response of melanoma cells to the combinatorial treatments. In SCID mice, the AZD6244-TRAIL association induced significant growth inhibition of a tumor resistant to TRAIL and poorly responsive to AZD6244, with no detectable adverse events on body weight and tissue histology. Reduction in tumor volume was associated not only with promotion of tumor apoptosis but also with suppression of the pro-angiogenic molecules HIF1α, VEGFα, IL-8 and TGFß1 and with inhibition of tumor angiogenesis. These results suggest that synergistic co-targeting of oncogenic and death receptor pathways can not only overcome melanoma resistance to different anti-tumor agents in vitro but can also promote pro-apoptotic effects and inhibition of tumor angiogenesis in vivo.

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.

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.

EGFR/MEK/ERK/CDK5-dependent integrin-independent FAK phosphorylated on serine 732 contributes to microtubule depolymerization and mitosis in tumor cells.

FAK is a non-receptor tyrosine kinase contributing to migration and proliferation downstream of integrin and/or growth factor receptor signaling of normal and malignant cells. In addition to well-characterized tyrosine phosphorylations, FAK is phosphorylated on several serines, whose role is not yet clarified. We observed that phosphorylated FAK on serine 732 (P-FAKSer732) is present at variable levels in vitro, in several melanoma, ovarian and thyroid tumor cell lines and in vivo, in tumor cells present in fresh ovarian cancer ascites. In vitro P-FAKSer732 was barely detectable during interphase while its levels strongly increased in mitotic cells upon activation of the EGFR/MEK/ERK axis in an integrin-independent manner. P-FAKSer732 presence was crucial for the maintenance of the proliferation rate and its levels were inversely related to the levels of acetylated α-tubulin. P-FAKSer732 localized at the microtubules (MTs) of the spindle, biochemically associated with MTs and contributed to MT depolymerization. The lack of the phosphorylation on Ser732 as well as the inhibition of CDK5 activity by roscovitine impaired mitotic spindle assembly and correct chromosome alignment during mitosis. We also identified, for the first time, that the EGF-dependent EGFR activation led to increased P-FAKSer732 and polymerized MTs. Our data shed light on the multifunctional roles of FAK in neoplastic cells, being involved not only in integrin-dependent migratory signaling but also in integrin-independent MT dynamics and mitosis control. These findings provide a new potential target for inhibiting the growth of tumor cells in which the EGFR/MEK/ERK/CDK5 pathway is active.

A single-chain fragment against prostate specific membrane antigen as a tool to build theranostic reagents for prostate cancer.

Prostate carcinoma is the most common non-cutaneous cancer in developed countries and represents the second leading cause of death. Early stage androgen dependent prostate carcinoma responds well to conventional therapies, but relatively few treatment options exist for patients with hormone-refractory prostate cancer. One of the most suitable targets for antibody-mediated approaches is prostate specific membrane antigen (PSMA) which is a well known tumour associated antigen. PSMA is a type II integral cell-surface membrane protein that is not secreted, and its expression density and enzymatic activity are increased progressively in prostate cancer compared to normal prostate epithelium, thereby making PSMA an ideal target for monoclonal antibody imaging and therapy. To obtain a small protein that can better penetrate tissue, we have engineered a single-chain variable fragment (scFv) starting from the variable heavy and light domains of the murine anti-PSMA monoclonal antibody D2B. scFvD2B was analysed in vitro for activity, stability, internalisation ability and in vivo for targeting specificity. Maintenance of function and immunoreactivity as well as extremely high radiolabelling efficiency and radiochemical purity were demonstrated by in vitro assays and under different experimental conditions. Despite its monovalent binding, scFvD2B retained a good strength of binding and was able to internalise around 40% of bound antigen. In vivo we showed its ability to specifically target only PSMA expressing prostate cancer xenografts. Due to these advantageous properties, scFvD2B has the potential to become a good theranostic reagent for early detection and therapy of prostate cancers.

Ligand-dependent EGFR activation induces the co-expression of IL-6 and PAI-1 via the NFkB pathway in advanced-stage epithelial ovarian cancer.

The epidermal growth factor receptor (EGFR), a member of the ErbB family of receptor tyrosine kinases, is expressed in up to 70% of epithelial ovarian cancers (EOCs), where it correlates with poor prognosis. The majority of EOCs are diagnosed at an advanced stage, and at least 50% present malignant ascites. High levels of IL-6 have been found in the ascites of EOC patients and correlate with shorter survival. Herein, we investigated the signaling cascade led by EGFR activation in EOC and assessed whether EGFR activation could induce an EOC microenvironment characterized by pro-inflammatory molecules. In vitro analysis of EOC cell lines revealed that ligand-stimulated EGFR activated NFkB-dependent transcription and induced secretion of IL-6 and plasminogen activator inhibitor (PAI-1). IL-6/PAI-1 expression and secretion were strongly inhibited by the tyrosine kinase inhibitor AG1478 and EGFR silencing. A significant reduction of EGF-stimulated IL-6/PAI-1 secretion was also obtained with the NFkB inhibitor dehydroxymethylepoxyquinomicin. Of 23 primary EOC tumors from advanced-stage patients with malignant ascites at surgery, 12 co-expressed membrane EGFR, IL-6 and PAI-1 by immunohistochemistry; both IL-6 and PAI-1 were present in 83% of the corresponding ascites. Analysis of a publicly available gene-expression data set from 204 EOCs confirmed a significant correlation between IL-6 and PAI-1 expression, and patients with the highest IL-6 and PAI-1 co-expression showed a significantly shorter progression-free survival time (P=0.028). This suggests that EGFR/NFkB/IL-6-PAI-1 may have a significant impact on the therapy of a particular subset of EOC, and that IL-6/PAI-1 co-expression may be a novel prognostic marker.

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.

E-cadherin directly contributes to PI3K/AKT activation by engaging the PI3K-p85 regulatory subunit to adherens junctions of ovarian carcinoma cells.

E-cadherin (cadh), a member of a family of integral membrane glycoproteins that represent the major component of adherens junctions (AJs), mediates cell-cell adhesion through the calcium-dependent homophilic interaction of its extracellular domain. Metastatic human carcinomas frequently lose E-cadh expression, whereas epithelial ovarian cancer (EOCs) maintain properties characteristic of Müllerian epithelium during tumor progression, including E-cadh expression. Here, we examined the potential role of cell-cell contacts in EOCs through E-cadh homophilic interactions in PI3K/AKT activation whose altered signaling has been implicated in EOC pathogenesis. We show that E-cadh is predominantly expressed at cell-cell contacts and its functionality is necessary and sufficient for the activation of the PI3K/AKT pathway. E-cadh knockdown and phosphoinositide-3-kinase (PI3K) inhibition complement each other in impairing cell-cycle progression and proliferation of ovarian carcinoma cells. E-cadh is stably bound to the PI3K complex, and the de novo formation of E-cadh/beta-catenin complexes following calcium deprivation and subsequent calcium restoration recruits the PI3K p85 subunit to the site of the cell-cell contacts. The finding that E-cadh-mediated AJ formation contributes to PI3K/AKT activation in EOC cells by a mechanism that appears to be restricted to these cells provides the underpinning for therapeutic strategies that exploit PI3K inhibition to halt EOCs.

Induction of a multifactorial resistance phenotype by high paclitaxel selective pressure in a human ovarian carcinoma cell line.

Paclitaxel (PTX) is a potent anti-neoplastic agent that is highly effective in treating ovarian cancer. Nevertheless, the emergence of PTX resistance has limited the control of this disease. To gain insight into the molecular alterations accompanying drug resistance in ovarian cancer, we generated a new stable PTX-resistant ovarian carcinoma cell line. CABA I cells, which display an intrinsic PTX resistance (IC50 = 800 ng/ml), were subjected to continuous exposure to PTX. From the residual surviving cells, the highly PTX-resistant line CABA-PTX (IC50 = 256000 ng/ml) was generated and stably maintained in vitro. Analysis of beta-tubulin expression indicated that only the HM40 and Hbeta9 isotypes were expressed in both parental and resistant cells. No specific point mutations in the HM40 were detected in either cell line, but expression levels of this isotype were significantly reduced (40%) in CABA-PTX cells. Hbeta9 levels were unchanged. In those cells, PTX resistance was associated with cross-resistance to vinblastine but not to methotrexate or 5-fluorouracil. Verapamil treatment did not reverse the intrinsic drug resistance of parental cells, but partially modulated the sensitivity of CABA-PTX cells to PTX and induced total sensitivity to vinblastine. No changes in the cell surface expression of the drug efflux pumps MRP1, MRP2 and P-glycoprotein were observed. PTX influx, monitored using a fluorescent drug derivative, was significantly reduced and delayed in CABA-PTX cells as compared to the parental cells. Together, these findings suggest that more than one mechanism is involved in PTX resistance, making CABA-PTX cell line a potentially valuable in vitro tool to study multifactorial acquired drug resistance in ovarian cancer.

Reversion of transformed phenotype in ovarian cancer cells by intracellular expression of anti folate receptor antibodies.

The alpha-folate receptor (FR) is selectively overexpressed in 90% of nonmucinous ovarian carcinomas, whereas no expression is detectable in normal ovarian surface epithelium (OSE). Indirect evidence suggests that FR expression is associated with tumor progression and affects cell proliferation. To evaluate better the role of FR, we developed an approach based on intracellular expression of single-chain (sc) antibodies (intrabody) to downmodulate membrane expression of FR in ovary cancer cells. IGROV-1 and SKOV3 ovarian carcinoma cell lines were transfected with an anti-FR intrabody. Transfectants and parental cells were tested for FR, integrins and anti-FR intrabody expression by fluorescence-activated cell sorting (FACS), reverse transcription and polymerase chain reaction (RT-PCR) and/or immunoblotting. Cell growth characteristics and adhesion properties were evaluated in liquid, semisolid and organotypic cultures. The anti-FR scFv inhibited FR expression from 60 to 99%. At physiological concentrations of folate, proliferation varied directly as a function of FR expression. FR downmodulation was accompanied by reduced colony-forming ability in soft agar, morphological change of the cells, significant enhanced adhesion to laminin or Matrigel, a two- to three-fold increase in alpha6beta4 integrin expression, and a marked reduction in laminin production. In three-dimensional organotypic cultures, anti-FR intrabody-transfected IGROV1 cells grew as a single-ordered layer, reminiscent of normal OSE growth in vivo. In conclusion, the anti-FR intrabody reverses the transformed phenotype in ovary cancer cells and may provide an efficient means to inhibit selectively the growth of these cells.

The humoral immune response to macrocyclic chelating agent DOTA depends on the carrier molecule.

UNLABELLED: The chelating agent 1,4,7,10-tetraazacyclododecane-N,N', N",N"'-tetraacetic acid (DOTA) is used to label monoclonal antibodies (mAbs) and peptides with (90)Y. DOTA allows the generation of clinically useful stable metallic radioconjugates for the treatment of a variety of tumors, but its immunogenicity has remained controversial. In this study, we evaluated the immune response to DOTA in a preclinical mouse model and in patients entered in a clinical trial. METHODS: Sera were obtained from BALB/c mice injected intraperitoneally or subcutaneously with different doses and formulations of syngeneic and xenogeneic mAbs or peptide (murine mAb Mov19 [mM19]; its chimeric version; murine V/human C ChiMov19 [cM19]; or Tyr(3)-octreotide)-DOTA conjugates. Sera from patients with neuroendocrine tumors, enrolled in a protocol for somatostatin receptor-mediated radionuclide therapy with (90)Y-DOTA-D-Phe(1)-Tyr(3)-octreotide (DOTATOC), were also collected before and after each treatment. Levels and specificity of antibody response to relevant (Mov19, ChiMov19, or Tyr(3)-octreotide) and nonrelevant (human serum albumin) DOTA targets were tested by enzyme-linked immunosorbent assay and competition assays. An anti-DOTA mAb (IgG1) derived from a ChiMov19-DOTA immunized mouse was used, in a competitive radioimmunoassay, to determine the efficiency of DOTA presentation on the different carriers. RESULTS: Depending on the immunogenicity and dosage of the mAb, a specific anti-DOTA response was revealed in the preclinical system. However, DOTA-peptide conjugate induced no immune-detectable response against either chelator or carrier. DOTA was poorly presented on small peptides, as determined using the anti-DOTA mAb. CONCLUSION: A humoral response against DOTA is possible, but only as a consequence of the response elicited against the carrier. Octreotide was not immunogenic. Thus, (90)Y-DOTATOC can be considered a safe and useful tool for receptor-mediated radionuclide therapy of somatostatin receptor-overexpressing tumors.

Exon 3 of the alpha folate receptor gene contains a 5' splice site which confers enhanced ovarian carcinoma specific expression.

The human folate receptor (FR) is overexpressed in ovarian carcinoma. FR transcripts are heterogeneous due to the use of two promoters, P1 and P4, and alternative splicing of exon 3. RNase protection assay and RT-PCR revealed higher levels of the transcripts that include exon 3 in lines and specimens from ovarian carcinoma. A P1-chloramphenicol acetyltransferase (CAT) construct containing exon 3 demonstrated efficient reporter expression only in ovarian carcinoma. 5' and 3' deleted variants of the P1-CAT construct were analyzed by RT-PCR of the exogenous transcripts and reporter activity. A 5' splice site and 35 bp downstream intronic region of exon 3 appeared to regulate enhanced FR expression in ovarian carcinoma.

Role of cytokines in cancer cachexia in a murine model of intracerebral injection of human tumours.

To study the role of cytokines that are relevant in cancer cachexia syndrome due to intracerebral tumours, mice were injected with human A431 epidermoid carcinoma, OVCAR3 ovarian carcinoma and GBLF glioma cells comparing intracerebral (i.c.) and systemic (i.p. or s.c.) routes of implantation. Anorexia and weight loss developed within 7-10 days in mice injected i.c. with A431 or OVCAR3 cells well before a large tumour developed, while i.c.-injected GBLF cells did not induce cachexia until day 20, when the tumour was large. By contrast, mice injected i.p. or s.c. developed tumours without evidence of anorexia. Thus, intracerebrally-growing A431 and OVCAR3 resulted in cancer cachexia independent of tumour mass, and we investigated their cytokine pattern. Serum levels of murine and human cytokines are not predictive of cancer cachexia development. Reverse-transcriptase polymerase chain reaction (RT-PCR) analysis revealed in the brain of i.c.-injected A431 tumour-bearing mice expression of human interleukin-(IL-)1alpha, IL-1beta and LIF in all samples and IL-6 in two of four samples while in i.c.-injected OVCAR3 tumour-bearing animals IL-6, and LIF were detected in all samples and tumour necrosis factor-alpha (TNFalpha) in two of four samples. Only LIF was expressed in brains of mice injected with GBLF cells. Murine IL-6 was increased only in the brains of A431-bearing mice. Only mice injected i.c. simultaneously with a monoclonal antibody (mAb) directed against the murine IL-6 receptor and OVCAR3 cells, but not those with mAb and A431 cells, showed a significant increase in survival time with a partial and temporary attenuation of cachexia symptoms. These results suggest that IL-6 in OVCAR3 model may be important cachectogenic factor when centrally released by even a limited number of tumour cells.

Decrease in drug accumulation and in tumour aggressiveness marker expression in a fenretinide-induced resistant ovarian tumour cell line.

We investigated whether the efficacy of fenretinide (HPR) against ovarian tumours may be limited by induction of resistance. The human ovarian carcinoma cell line A2780, which is sensitive to a pharmacologically achievable HPR concentration (IC(50)= 1 microM), became 10-fold more resistant after exposure to increasing HPR concentrations. The cells (A2780/HPR) did not show cross-resistance to the synthetic retinoid 6-[3-adamantyl-4-hydroxyphenyl]-2-naphthalene carboxylic acid (CD437) and were not sensitive, similarly to the parent line, to all-trans-retinoic acid, 13-cis-retinoic acid or N-(4-methoxyphenyl)retinamide. A2780/HPR cells showed, compared to parental cells, a 3-fold reduction in colony-forming ability in agar. The development of HPR resistance was associated with a marked increase in retinoic acid receptor beta (RARbeta) mRNA and protein levels, which decreased, together with drug resistance, after drug removal. The expression of cell surface molecules associated with tumour progression including HER-2, laminin receptor and beta1 integrin was markedly reduced. The increase in the levels of reactive oxygen species is not involved in HPR-resistance because it was similar in parental and resistant cells. Conversely differences in pharmacokinetics may account for resistance because, in A2780/HPR cells, intracellular peak drug levels were 2 times lower than in A2780 cells and an as yet unidentified polar metabolite was present. These data suggest that acquired resistance to HPR is associated with changes in marker expression, suggestive of a more differentiated status and may be explained, at least in part, by reduced drug accumulation and increased metabolism.