RESUMO
A new pentadecapeptide bombesin analogue was prepared by Fmoc synthesis, purified by HPLC and identified by electron ionization mass spectrometry. The biological activity of the new peptide was tested on isolated human colonic muscle cells and compared to native bombesin. Labelling of the new biomolecule with Tc-99m yielded a single radioactive species which remained stable at room temperature for eight hours. In a binding assay, the radiolabelled peptide showed high affinity for oat-cell carcinoma (Kd = 9.8 nM) and colorectal adenocarcinoma (Kd = 27.2 nM). Biodistribution studies, performed in normal rodents, indicated uptake by organs that normally express bombesin receptors, such as liver, intestines and kidneys. Scintigraphic studies, performed in nude mice transplanted with small cell lung carcinoma and colon cancer cells, showed significant tumor uptake two hours p.i. The new synthetic pentadecapeptide appears to have promise for several malignancies, including oat-cell lung carcinoma, colorectal cancer and gastroenteropancreatic (GEP) tumors.
Assuntos
Bombesina , Carcinoma de Células Pequenas/diagnóstico por imagem , Neoplasias do Colo/diagnóstico por imagem , Neoplasias Pulmonares/diagnóstico por imagem , Peptídeos , Pertecnetato Tc 99m de Sódio , Animais , Bombesina/síntese química , Bombesina/farmacocinética , Carcinoma de Células Pequenas/metabolismo , Neoplasias do Colo/metabolismo , Feminino , Humanos , Marcação por Isótopo , Neoplasias Pulmonares/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Transplante de Neoplasias , Peptídeos/síntese química , Peptídeos/farmacocinética , Cintilografia , Ratos , Ratos Wistar , Receptores da Bombesina/metabolismo , Distribuição Tecidual , Células Tumorais CultivadasRESUMO
A tumour-associated radiolabelled monoclonal antibody (Mab) 131I-OC 125 F(ab')2 was used to investigate 27 patients 2 weeks after their last chemotherapy regimen and prior to second-look surgery for ovarian cancer. We did compare the radioimmunoscintigraphy (RIS) findings with the CT scan results and the second-look operation data. In 23 out of 27 cases the RIS results correlated with the operation findings, while there were four false-negative results. Computed tomography (CT) scans correlated in 17 out of 23 cases with the operative findings, while there were six false-negative results. We concluded that RIS is more specific in detecting the tumour site within the pelvis, while CT scan is superior in detecting liver metastases.