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Biomedical subjects

Rolando Pérez

Publications and source records attributed to Rolando Pérez.

At least 19 recordsLinked to original sources
PubMed2007

Active immunotherapy with 1E10 anti-idiotype vaccine in patients with small cell lung cancer: report of a phase I trial.

1E10 is an anti-idiotype murine monoclonal antibody (Ab2 MAb) specific to an Ab1 MAb which reacts with NeuGc-containing gangliosides, sulfatides and with antigens expressed in some human tumors. Preparations containing this Ab2 were capable to induce a strong anti-metastatic effect in tumor-bearing mice. We conducted a Phase I clinical trial to evaluate the toxicity and humoral immune response elicited by 1E10 vaccine in patients with small cell lung cancer (SCLC). Eligible patients were those who after received chemotherapy and/or radiotherapy had partial or complete response to treatment. Patients received four biweekly injections with 2 mg of aluminum hydroxide-precipitated 1E10 MAb, then other six doses at 28-day intervals, and later the patients who maintained a good performance status were reimmunized. Six patients with limited-stage disease and three with extensive-stage disease were enrolled in the study. Most of the patients who received at least four doses of 1E10 vaccine developed strong specific antibody responses against 1E10 MAb and NeuGc-GM3 ganglioside. Antibodies able to react with lung carcinoma tissue sections were detected in sera from vaccinated patients. A prolonged survival was observed in several patients treated with the anti-idiotype vaccine. No evidence of serious adverse effects was found.

Aged↗
PubMed2006

Treatment of high-grade glioma patients with the humanized anti-epidermal growth factor receptor (EGFR) antibody h-R3: report from a phase I/II trial.

The poor prognosis of patients with high-grade glioma has led to the search for new therapeutic strategies. More than half of these tumors overexpress Epidermal Growth factor Receptor (EGFR). h-R3 is a humanized monoclonal antibody that recognize the EGFR external domain with high affinity, inhibiting tyrosine kinase activation. In order to evaluate safety, immunogenicity and preliminary efficacy of h-R3 in newly diagnosed high-grade glioma patients, we conducted a Phase I/II trial. Patients received six weekly infusions of h-R3 at the dose of 200 mg in combination with external beam radiotherapy. Twenty-nine patients (mean age, 45 years and median KPS 80) were entered into the study. Tumor types were: glioblastoma (GB) (16 patients), anaplastic astrocytoma (AA) (12 patients) and anaplastic oligodendroglioma (AO) (1 patient). All patients underwent debulking surgery or biopsy before entering the trial. The antibody was very well tolerated. No evidences of grade 3/4 adverse events were detected. None of the patients developed acneiform rash or allergic reactions. One patient developed a positive anti-idiotypic response. Objective response-rate was 37.9% (17.2% complete response, 20.7% partial response) while stable disease occurred in 41.4% of the patients. With a median follow up time of 29 months, the median survival is 22.17 months for all subjects. Median survival time (MST) is 17.47 months for GB, whereas MST is not reached for AA patients.

Adult↗
PubMed2006

Gangliosides, Ab1 and Ab2 antibodies II. Light versus heavy chain: An idiotype-anti-idiotype case study.

The antibody heavy chain is generally more important than the light chain for the interaction with the antigen, although many reports demonstrate the influence of the light chain in the antibody binding properties. The heavy chains of anti-N-glycolyl-ganglioside P3 mAb and anti-idiotypic 1E10 mAb display complementary charged residues in their H-CDRs, particularly in H-CDR3. A basic residue in P3 mAb H-CDR1 was shown to be crucial for the interaction with the antigen and 1E10 mAb. The immunogenetic features of three other P3 mAb anti-idiotypic mAbs are now analyzed. One of them bears the same heavy chain as 1E10 mAb and a different light chain, but differs in its binding to P3 mAb mutants where H-CDR basic residues were replaced and in the binding to 1E10-specific phagotopes. Chimeric hybrid antibodies with P3 and 1E10 mAb heavy chains and unrelated light chains were obtained to further determine the importance of heavy chains in P3 and 1E10 mAb binding properties. One of the P3 heavy chain hybrid antibodies retained the specificity of P3 mAb with slight affinity differences. The heavy chains appear to play the main role in these mAb interactions, with the light chains modulating the affinity to their ligands.

Amino Acid Sequence↗
PubMed2006

Gangliosides, Ab1 and Ab2 antibodies I. Towards a molecular dissection of an idiotype-anti-idiotype system.

This report is focused on the molecular basis for the interaction of a monoclonal antibody (mAb) and its anti-idiotypic mAb. P3 mAb (Ab1) recognizes N-glycolyl-gangliosides, and 1E10 mAb is one of its anti-idiotypic mAbs (Ab2). Chimeric versions of both antibodies retained their specificity. Charged residues in their H-CDRs, particularly H-CDR3, were considered to play a major role in their binding and immunogenic properties. P3 mAb has the unusual property of generating a strong antibody response in syngeneic mice, even when it is administered in saline. We selected phagotopes from a 12mer peptide library displayed on filamentous phage to characterize amino acid motifs recognized by these antibodies. The peptides were enriched in charged amino acids similar to those present in P3 and 1E10 mAb H-CDR3. We also report the construction of four mutants of the P3 antibody, where arginine residues in the heavy chain CDRs were substituted by serine residues, and the characterization of their interaction with 1E10 mAb and GM3(NeuGc) ganglioside, as well as their immunogenic properties in Balb/c mice. H-CDR1 R31 residue appears to have a central role in P3 mAb reactivity and antigenicity. H-CDR3 R100a residue seems to be more involved in the immunogenicity of the P3 idiotype.

Animals↗
PubMed2005

Alkyl-linked bis-THTT derivatives as potent in vitro trypanocidal agents.

The effect of several alkyl-linked bis tetrahydro-(2H)-1,3,5-thiadiazine-2-thione (bis-THTT) on Leishmania donovani, Trypanosoma brucei rhodesiense, and Plasmodium falciparum is reported. Most of the compounds exhibited a potent activity against the three parasitic strains but the best in vitro activity profiles were found against T. b. rhodesiense with IC(50) values ranging between 0.3 and 4 microM for the most active compounds.

Alkylation↗
PubMed2005

Clinical evidences of GM3 (NeuGc) ganglioside expression in human breast cancer using the 14F7 monoclonal antibody labelled with (99m)Tc.

The relevance of certain gangliosides in tumour growth and metastatic dissemination has been well documented, reasons for considering these molecules as potential targets for cancer immunotherapy and diagnosis. GM3(NeuGc) ganglioside is particularly interesting due to its restrictive expression in normal human tissues according to immunohistochemical studies, using either polyclonal or monoclonal antibodies. But both immunohistochemical and biochemical methods have strongly suggested its over-expression in human breast tumours. Nevertheless, the lack of a direct evidence of this antigenic display in human breast cancer has kept the subject controversial. For the first time, we described herein the "in vivo" detection of GM3(NeuGc) ganglioside in human breast primary tumours using a radioimmunoscintigraphic technique with 14F7, a highly specific anti-GM3(NeuGc) ganglioside monoclonal antibody, labelled with (99m)Tc. In an open, prospective Phase I/II clinical trial, including women diagnosed in stage II breast cancer, the 14F7 monoclonal antibody accumulation in tumours at doses of 0.3 (n=5), 1 (n=5) and 3 mg (n=4) was evaluated. Noteworthy, the immunoscintigraphic study showed antibody accumulation in 100% of patients' tumours for the 1 mg dose group. In turn, the radioimmunoconjugate injected at doses of 0.3 mg or 3 mg of the antibody, was uptaken by 60 and 33.3% of breast tumours, respectively. "In vivo" immune recognition of GM3(NeuGc) in breast tumours reinforces the value of this peculiar target for cancer immunotherapy.

Adolescent↗
PubMed2005

Quantitative structure antitumoral-activity relationships of thiadiazinthione derivatives using the novel hybrid molecular index pMRchi.

PURPOSE: The recently defined molar-refractivity-partition index was applied to a family of 1,3,5- thiadiazin-2-thione derivatives in order to establish quantitative structure-antitumoral models. The goal of this effort is to establish the relationships between the structure and biological response of these compounds. METHOD: After the splitting of the sample in two sets, their indices were correlated against the measured biological activity. The combined use of our index with others had been able to describe not only the topologic but also the London dispersive forces of any fragment in relation to the biological response of the sets. RESULTS: The obtained models showed correlation coefficients of 0.87 and 0.81 respectively linking structural and biological features of the molecules. The mean relative error values were less than 7%. According to the models, the activity of the first sample is related mostly to molecular topology and dispersive forces. Sample two activity was associated to the size and branching of the substituents, and also to the London forces. CONCLUSION: The index was able to discriminate between pure topological features and those related to dispersive forces.

Antineoplastic Agents↗
PubMed2005

The enlargement of the hormone immune deprivation concept to the blocking of TGFalpha-autocrine loop: EGFR signaling inhibition.

Transforming growth factor alpha (TGFalpha) is a potent ligand of the epidermal growth factor receptor (EGFR). EGFR is frequently over-expressed in epithelial tumors and endogenous ligands, mostly TGFalpha, are frequently co-expressed with EGFR, potentially resulting in autocrine stimulation of tumor cell growth. Therefore, different therapeutic approaches aim for the inactivation of TGFalpha/EGF/EGFR signaling system, but no approach is based on TGFalpha as a target. The principal goal of this work was to assess the potential of an active specific immunotherapy approach to block the TGFalpha/EGFR autocrine loop. For the proof of the concept, a fusion protein between human TGFalpha (hTGFalpha) and P64k protein from Neisseria meningitidis was generated, and its immunogenicity characterized in a mouse model using different adjuvants. All immunogens were effective for the generation of specific humoral responses against hTGFalpha. The inmunodominant epitope of hTGFalpha when immunizing mice with the fusion protein involved the C-loop/C-terminal region. This region includes key residues for hTGFalpha binding to EGFR. The anti-hTGFalpha immune mice sera recognized the natural hTGFalpha precursor in A431 cells and hTGFalpha-transfected 3T3 fibroblasts as revealed by flow cytometry analysis and immunoblotting. They inhibited the binding of (125)I-TGFalpha to the EGFR, EGFR-autophosphorylation, and downstream activation of MAP kinases as well as proliferation of two EGFR-expressing human carcinoma cell lines. These data suggest that EGFR signaling activation by the hTGFalpha autocrine loop may be inhibited in vivo by induction of specifically blocking antibodies. The fusion protein reported in this paper could be a potential immunogen for the development of a new cancer vaccine.

Animals↗
PubMed2005

Generation of anti-Neu-glycolyl-ganglioside antibodies by immunization with an anti-idiotype monoclonal antibody: A self versus non-self-matter.

We have previously generated a murine anti-idiotype (Ab2) monoclonal antibody (mAb) to a murine Ab1 mAb, named P3, which selectively binds Neu-glycolyl (NeuGc)-sialic acid on several monosialo- and disialogangliosides, and also reacts with sulfatides and antigens expressed in human melanoma and breast tumors. This Ab2 mAb, designated as 1E10, induced anti-anti-idiotype antibodies (Ab3) in mice and cancer patients. These Ab3 generated by 1E10 mAb were characterized by bearing P3 mAb idiotopes (Ab3, Id +). But when the specificity of these Ab3 antibodies was tested, no specific humoral response against NeuGc-containing gangliosides was detected in sera from immunized mice. However, hyperimmune sera from melanoma and breast cancer patients vaccinated with this Ab2 mAb were able to react specifically with these gangliosides. The different expression of NeuGc-containing gangliosides in the normal tissues of mice and humans could explain these results. In order to demonstrate these findings in other animal species with a different NeuGc-sialic acid expression, we performed similar studies in monkeys and chickens. In monkeys, as in most mammals, NeuGc-containing gangliosides are self-antigens. In contrast, chickens, like humans, lack the expression of these antigens in normal tissues. Here we report that the antibody response against NeuGc-containing gangliosides induced by immunization with 1E10 mAb was completely different in both species. No specific antibody response against these gangliosides was detected in hyperimmune monkey sera. In contrast, a strong and specific Ab3 response against GM3(NeuGc) and GM2(NeuGc) gangliosides (Ab3, Ag+) was generated in chickens due to the administration of 1E10 mAb.

Animals↗
PubMed2005

In vitro activities of thiadiazine derivatives against Leishmania amazonensis.

Ten thiadiazine derivatives were tested in vitro for antiparasitic effects against both extracellular promastigotes and intracellular amastigotes of Leishmania amazonensis. The results showed that the evaluated compounds exhibited a strong antiproliferative activity on all developmental stages of the parasite. The minimal inhibitory concentration and the 50 % effective concentration values against the promastigote were 2.1-5.1 microg/ml and 0.6-1.8 microg/ml, respectively. The tested compounds caused an irreversible inhibition of the promastigote growth either after 1 h of treatment with 10 microg/ml or after 24 h with 1 microg/ml. Also, the thiadiazine derivatives were active against amastigotes producing between 12 and 89 % of reduction of infection at 100 ng/ml. However, the compounds exhibited high toxicity and provoked inhibition of the phagocytosis in the murine host cell.

Animals↗
PubMed2004

Use of the humanized anti-epidermal growth factor receptor monoclonal antibody h-R3 in combination with radiotherapy in the treatment of locally advanced head and neck cancer patients.

PURPOSE: To evaluate safety and preliminary efficacy of the humanized anti-epidermal growth factor receptor monoclonal antibody h-R3 in combination with radiotherapy (RT) in unresectable head and neck cancer patients. Secondary end points were the measurement of h-R3 serum levels and the assessment of the potential mechanisms of antitumor effect on patient biopsies. Anti-idiotypic response to h-R3 was assessed. To predict pharmacologic effect, a mathematical model for antibodies recognizing antigens expressed in tumors and normal tissues was built. PATIENTS AND METHODS: Twenty-four patients with advanced carcinomas of the head and neck received six once-weekly infusions of h-R3 at four dose levels in combination with RT. Pretreatment tumor biopsies were obtained to evaluate epidermal growth factor receptor expression as an enrollment criterion. Second biopsies were taken to evaluate the proliferative activity and angiogenesis in comparison with the pretreatment samples. Patient serum samples were collected to measure h-R3 levels and anti-idiotypic response. RESULTS: The combination of h-R3 and RT was well tolerated. Antibody-related adverse events consisted in infusion reactions. No skin or allergic toxicity appeared. Overall survival significantly increased after the use of the higher antibody doses. Immunohistochemistry studies of tumor specimens before and after treatment revealed that antitumor response correlated with antiproliferative and antiangiogenic effect. One patient developed antibodies to h-R3. The mathematical model predicted that the maximum difference between the area under the curve in tumors and normal tissues is reached when the antibody has intermediate affinity. CONCLUSION: h-R3 is a well-tolerated drug that may enhance radiocurability of unresectable head and neck neoplasms.

Aged↗
PubMed2003

Immunotherapy of advanced breast cancer with a heterophilic ganglioside (NeuGcGM3) cancer vaccine.

PURPOSE: A heterophilic ganglioside cancer vaccine was developed by combining NeuGcGM3 with the outer membrane protein complex of Neisseria meningitidis to form very small size proteoliposomes (VSSP). A phase I clinical trial was performed to determine safety and immunogenicity of this vaccine. PATIENTS AND METHODS: Stage III to IV breast cancer patients received up to 15 (200 micro g) doses of the vaccine by intramuscular injection. The first five doses (induction phase) were given at 2-week intervals, with the remaining treatment (maintenance) administered on a monthly basis. RESULTS: Twenty-one patients, 11 of whom had metastatic disease, were included. Main toxicities included erythema and induration at the injection site, sometimes associated with mild pain, and low-grade fever (World Health Organization grades 1 and 2). All treated patients who completed the induction phase developed anti-NeuGcGM3 antibody titers between 1:1,280 and 1:164,000 immunoglobulin G (IgG), and 1:640 and 1:164,000 IgM. Noteworthy specific IgA antibodies were induced by vaccination in all stage III patients and in three stage IV patients. Serum antibody levels were higher in the stage III patients, with the larger increases observed after week 32. The antiganglioside IgG subclasses were mainly IgG1 and IgG3. Hyperimmune sera increased complement-mediated cytotoxicity versus P3X63 myeloma cells and a marked IgG differential reactivity against human mammary ductal carcinoma samples. CONCLUSION: NeuGcGM3/VSSP/Montanide ISA 51 is an unusual immunogenic ganglioside vaccine and also seems to be safe in this small trial. Immunologic surrogates of activity indicate that this reagent warrants further investigation.

Adult↗
PubMed2003

Immune responses in breast cancer patients immunized with an anti-idiotype antibody mimicking NeuGc-containing gangliosides.

A phase I clinical trial was conducted in patients with stage III/IV breast cancer who were treated with the anti-idiotype mAb 1E10 specific to an Ab1 mAb able to react specifically with N-glycolyl-containing gangliosides and with antigens expressed on human melanoma and breast carcinoma cells. Patients were treated with 1 or 2 mg of aluminum hydroxide-precipitated 1E10 mAb every other week for six injections. Two patients at each dose were reimmunized 7-9 months after completing the induction phase. In hyperimmune sera from eight of the nine patients who received at least four doses of anti-Id vaccine preparations, strong specific responses were observed both against 1E10 mAb and NeuGc-GM3 ganglioside (Ab3 Id+Ag+). Nonclassical Ab1' antibodies (Id-Ag+) were also elicited by 1E10 mAb vaccine treatment. There were no differences between the two levels of dose tested in relation to toxicity and immunogenicity. No evidence of serious or unexpected effects was observed.

Adult↗
PubMed2003

Chimeric anti-N-glycolyl-ganglioside and its anti-idiotypic MAbs: immunodominance of their variable regions.

P3 monoclonal antibody (MAb) is a murine IgM that specifically recognizes N-glycolyl (NeuGc)-gangliosides and sulfatides. It also reacts with antigens expressed in human breast tumors and melanoma. In syngeneic model, P3 MAb is able to elicit a strong anti-idiotypic (Ab2) antibody response, even in the absence of adjuvants or carrier proteins. 1E10 MAb is an anti-idiotypic antibody specific for P3 MAb that has demonstrated anti-tumoral effects in syngeneic and allogeneic animals. Here we report the construction of the human IgG(1) chimeric P3 and 1E10 antibodies, and the evaluation of the maintenance of the main properties of the murine MAbs. Chimeric P3 antibody specifically reacted with GM3(NeuGc) and GM2(NeuGc) gangliosides, and not with their acetylated variants. Also, it strongly recognized the anti-idiotypic 1E10 MAb. Chimeric 1E10 antibody specifically reacted with P3 MAb. Upon immunization of Balb/c mice with both chimeric antibodies, we were able to demonstrate the immunodominance of their variable regions. The anti-idiotypic response induced by both antibodies was strong and in most of the mice was even significantly higher than the anti-isotypic response, despite the fact that 70% of the chimeric molecule is xenogenic with respect to the animal model.

Animals↗
PubMed2003

Humanization of predicted T-cell epitopes reduces the immunogenicity of chimeric antibodies: new evidence supporting a simple method.

Genetic engineering has provided several approaches to reduce immunogenicity of murine antibodies. We described previously a new method based on the humanization of the linear epitopes presented to T cells. In brief, potential immunogenic epitopes in the variable region were identified and subjected to point mutations to make them human and/or to modify amphipatic motifs. The resulting recombinant antibody retained its antigen binding affinity and was less immunogenic in monkeys than their murine or chimeric predecessors are. The present study provides two new examples of this T-cell epitope humanization approach: ior-t1A murine monoclonal antibody (mMAb), which recognizes the human-CD6 molecule, and ior-C5 mMAb, which recognizes a novel glycoprotein expressed on the surface of malignant colorectal cells. Seven amino acids were substituted in ior-C5 and eleven residues in ior-t1A, by the corresponding residues from the highest homologous human sequences. Surprisingly, the homology between re-shaped chimeric antibody variable region frameworks and human sequences was 80-90%. Experiments in monkeys showed that T1AhT and C5hT "detopes" antibodies were less immunogenic than their chimeric analogues while they retained 30-50% of antigen binding affinities. The proposed method might be of general applicability to reduce immunogenicity of chimeric antibodies with therapeutic potential.

Algorithms↗
PubMed2003

Generation and characterization of an anti-idiotype monoclonal antibody related to GM3(NeuGc) ganglioside.

The 14F7 monoclonal antibody (MAb), IgG1 isotype, which reacts specifically to GM3(NeuGc) ganglioside induced a specific IgG anti-idiotypic antibody (Ab2) response in syngeneic mice when it was administered coupled with KLH and in the presence of Freund's adjuvant. Spleen cells from these mice were used in somatic-cell hybridization experiments using the murine myeloma cell line P3-X63-Ag8 653 as fusion partner. An IgG1 Ab2 MAb was selected. This Ab2 MAb, called 4G9, was able to block the binding of 14F7 MAb to GM3(NeuGc) ganglioside and developed a strong IgG anti-anti-idiotypic antibody (Ab3) response, when injected into syngeneic mice. These Ab3 antibodies were characterized to bear 14F7 MAb idiotopes, but did not have the same specificity as 14F7 MAb. In the other hand, a very specific anti-NeuGc-containing ganglioside response was generated in chickens immunized with this Ab2 MAb, thus behaving, in this species as an "internal image" antibody.

Animals↗