Antitumor efficacy, pharmacokinetic and biodistribution studies of the anticancer peptide CIGB-552 in mouse models.

Accumulation of the COMMD1 protein as a druggable pharmacology event to target cancer cells has not been evaluated so far in cancer animal models. We have previously demonstrated that a second-generation peptide, with cell-penetrating capacity, termed CIGB-552, was able to induce apoptosis mediated by stabilization of COMMD1. Here, we explore the antitumor effect by subcutaneous administration of CIGB-552 in a therapeutic schedule. Outstandingly, a significant delay of tumor growth was observed at 0.2 and 0.7 mg/kg (p < 0.01) or 1.4 mg/kg (p < 0.001) after CIGB-552 administration in both syngeneic murine tumors and patient-derived xenograft models. Furthermore, we evidenced that (131)I-CIGB-552 peptide was actually accumulated in the tumors after administration by subcutaneous route. A typical serine-proteases degradation pattern for CIGB-552 in BALB/c mice serum was identified. Further, biological characterization of the main metabolites of the peptide CIGB-552 suggests that the cell-penetrating capacity plays an important role in the cytotoxic activity. This report is the first in describing the antitumor effect induced by systemic administration of a peptide that targets COMMD1 for stabilization. Moreover, our data reinforce the perspectives of CIGB-552 for cancer targeted therapy.

Diagnostic efficacy and safety of 99mtc-labeled monoclonal antibody ior c5 in patients with colorectal and anal carcinomas: final report clinical trial phase I/II.

UNLABELLED: Monoclonal antibody (mAb) ior c5 is an IgG1, which recognizes a glycoprotein tumor specific antigen IOR C2 over expressed in the surface of colon and ovarian cancer cells. The aim of the present work was to evaluate the diagnostic efficacy of the 99mTc-labeled mAb ior c5 for the detection of colorectal tumors, its metastases and recurrences. METHODS: Eighty six patients with colorectal or anal cancer, mean age 57 +/- 13 yrs, were involved in a phase 1/11 multicentric, open clinical trial to assess the ability of Radioimmunoscintigraphy (RIS) with 99mTc- mAb ior c5 to detect those tumors. Seventy-four patients received 1 mg of c5 labeled with 1480-1850 MBq to determinate diagnosis efficacy and safety of murine mAb by intravenously (i.v.) bolus injection (group 1). In order to evaluate pharmacokinetic, bio distribution and dosimetry of this radiolabel molecule, 12 patients received 3 mg of labeled ior c5. Planar anterior and posterior images of the lesion sites and suspected metastases were acquired at 2, 4 and 18-24 hours after injection using a matrix size 128 x128 and 500 Kcounts per view. SPECT were scanned at 5 hr post-injection, using a 360' circular orbit with 64 images. HAMA response was measured in serum at 2, 4, 8 and 12 week post-administration. RESULTS: Labeling efficiency was (97.8 - 0.6) %. No adverse reactions or side effects were observed. Overall sensitivity, specificity, accuracy, positive and negative predictive values of the immunoscintigraphy were 95.80%, 100%, 96.51%, 100.0% and 82.35%, respectively. Unknown metastases were detected in 37 of 86 cases (43.02%). No HAMA response was found. CONCLUSIONS: Immunoscintigraphy with 99mTc-labeled mAb ior c5 could be a useful procedure for the diagnosis and follow-up of the patients with colorectal tumors, its metastasis and recurrences.

A multivalent recombinant antibody fragment specific for carcinoembryonic antigen.

In the present paper we report the development of a bivalent scFv (single-chain Fv) antibody fragment, starting from a mouse mAb (monoclonal antibody) specific for CEA (carcinoembryonic antigen) that has received approval for in vivo radioimmunodiagnosis in humans. The diabody is well expressed in Escherichia coli, is easily purified by a combination of immobilized metal ion affinity chromatography and gel filtration and exhibits high affinity and specificity for CEA, comparable with those of the original mAb. Biodistribution experiments in athymic nude mice transplanted with human CEA+ cancer cells showed that the 125I-labelled diabody preferentially localizes in the tumour tissue and that retention is still high 48 h after injection. The diabody can be advantageous for some in vivo tumour targeting applications, due to the faster clearance derived from its smaller molecular mass.

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.

Obtención y purificación de fragmentos de un anticuerpo monoclonal contra el antígeno carcinoembrionario, IOR-CEA / Preparation and purification of fragments of monoclonal antibodies over carcinoembrionic antigen, IOR-CEA

La idea de utilizar los anticuerpos monoclonales (AcMs) como portadores de otras moléculas tóxicas a las células neoplásicas, para provocar la muerte celular de forma específica ha sido utilizada por diversos grupos de investigación. Se han utilizado anticuerpos monoclonales para el diagnóstico de neoplasias malignas y sus metástasis, fundamentalmente en el campo de la medicina nuclear, mediante técnicas de inmunogammagrafía. Sin embargo, en algunos casos resulta más ventajoso la utilización de los fragmentos de los anticuerpos monoclonales ya que, debido a su tamaño molecular presentan mayor aclaramiento del torrente sanguíneo con mayor acumulación en el tejido blanco y menor probabilidad de formación de inmunocomplejos. El objetivo del presente artículo consiste en la obtención de fragmentos Fab y F (ab')2 a partir del anticuerpo monoclonal IOR-CEA, generado contra el antígeno carcinoembrionario. La obtención de los fragmentos Fab y F (ab')2 se realizó mediante digestión enzimática con papaína y pepsina, respectivamente. Se utilizaron las enzimas acopladas a una matriz de AH-Serapharosa para facilitar la separación de las mismas de la mezcla al concluir la reacción. Los resultados fueron satisfactorios con respecto a la obtención del fragmento Fab, no siendo así para los fragmentos F (ab')2, debido a que la pepsina, una vez acoplada a la matriz, perdió su actividad enzimática. Una vez establecidas las condiciones de reacción se obtuvieron los fragmentos Fab y se purificaron mediante una cromatografía de afinidad utilizando una matriz de proteínas A-Sepharosa, con un rendimiento de un 85 por ciento y manteniéndose su actividad biológica, lo cual fue ensayado utilizando técnicas de ELISA e inmunohistoquímica en cortes de tejido. El marcaje con 99mTc fue efectivo manteniéndose la actividad biológica de los fragmentos Fab, lo que los hace ser buenos candidatos para su utilización en la detección de tumores colorrectales y sus met stasis mediante inmunogammagrafía.