Abdul Mutalib

Synthesis and stability test of radiogadolinium(III)-DOTA-PAMAM G3.0-trastuzumab as SPECT-MRI molecular imaging agent for diagnosis of HER-2 positive breast cancer

Abstract Nonivasive diagnosis of cancer can be provided by molecular imaging using hybrid modality to obtain better sensitivity, specificity and depiction localization of the disease. In this study, we developed a new molecular imaging agent, radiogadolinium(III)-DOTA-PAMAM G3.0-trastuzumab in the form of 147Gd-DOTA-PAMAM G3.0-trastuzumab, that can be both target-specific radiopharmaceutical in SPECT as well as targeted contrast agent in MRI for the purpose of diagnosis of HER-2 positive breast cancer. 147Gd radionuclide emits γ-rays that can be used in SPECT modality, but because of technical constraint, 147Gd radionuclide was simulated by its radioisotope, 153Gd. Gd-DOTA complex has also been known as good MRI contrast agent. PAMAM G3.0 is useful to concentrate Gd-DOTA compelexes in large quantities, thus minimizing the number of trastuzumab molecules used. Trastuzumab is human monoclonal antibody that can spesifically interact with HER-2. Synthesis of radiogadolinium(III)-DOTA-PAMAM G3.0-trastuzumab was initiated by conjugating DOTA NHS ester ligand with PAMAM G3.0 dendrimer. The DOTA-PAMAM G3.0 produced was conjugated to trastuzumab molecule and labeled with 153Gd. Characterization DOTA-PAMAM G3.0-trastuzumab immunoconjugate was performed using HPLC system equipped with SEC. The formation of immunoconjugate was indicated by the shorter retention time (6.82 min) compared to that of trastuzumab (7.06 min). Radiochemical purity of radiogadolinium(III)-DOTA-PAMAM G3.0-trastuzumab was >99% after purification process by PD-10 desalting column. Radiogadolinium(III)-DOTA-PAMAM G3.0-trastuzumab compound was stable at room temperature and at 2–8 0C as indicated by its radiochemical purity 97.6 ± 0.5%–99.1 ± 0.5% after 144 h storage.

Synthesis and stability test of radioimmunoconjugate 177Lu-DOTA-F(ab′)2-trastuzumab for theranostic agent of HER2 positive breast cancer

Abstract The use of trastuzumab as intact IgG labeling radionuclide for HER2 positive breast cancer theranostic agent is not ideal because it is slowly eliminated from the blood and normal tissues resulting in low tumor/blood (T/B) and tumor/normal tissue (T/NT) ratios. To overcome this limitation, we developed the trastuzumab F(ab′)2 fragments and radiolabeling of the fragments by β and γ-particle of Lutetium-177. F(ab)2 fragments were produced by digestion of trastuzumab IgG (Herceptin) with pepsin for 18 h at 37 °C. The F(ab′)2 fragment fractionated in PD-10 column, followed by the conjugation with 2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (p-SCN-Bn-DOTA) as a metal chelator and radiolabeling with 177LuCl3. Molecular weight of fragments was calculated by LCMS (Liquid Chromatography Mass Spectroscopy) and the radiochemical purity was evaluated by ITLC-SG (Instan Thin Layer Chromatography). Our study showed that the purity of F(ab′)2 fragment generated by PD-10 fractions was >98% and the molecular weight of F(ab′)2 was 98.35 kDa. The average numbers of pSCN-Bn-DOTA chelates per antibody fragment were 5.03 ± 1.5 and the optimum conjugation reactions was performed at molar ratio 20:1 (chelator to antibody). The stability test of the radioimmunoconjugate in the human serum albumin (HSA) at 37 °C showed the radiochemical purity was 91.96 ± 0.26% after 96 h storage. This indicated that the radioimmunoconjugate is relatively stable when applied to the human bodys physiological condition.

Fast and simultaneously determination of light and heavy rare earth elements in monazite using combination of ultraviolet-visible spectrophotometry and multivariate analysis

Rare Earth Elements (REE) are elements that a lot of function for life, such as metallurgy, optical devices, and manufacture of electronic devices. Sources of REE is present in the mineral, in which each element has similar properties. Currently, to determining the content of REE is used instruments such as ICP-OES, ICP-MS, XRF, and HPLC. But in each instruments, there are still have some weaknesses. Therefore we need an alternative analytical method for the determination of rare earth metal content, one of them is by a combination of UV-Visible spectrophotometry and multivariate analysis, including Principal Component Analysis (PCA), Principal Component Regression (PCR), and Partial Least Square Regression (PLS). The purpose of this experiment is to determine the content of light and medium rare earth elements in the mineral monazite without chemical separation by using a combination of multivariate analysis and UV-Visible spectrophotometric methods. Training set created 22 variations of concentration an...

BINDING AFINITY OF ANTIBODY MONOCLONAL TRASTUZUMAB AND HUMAN EPIDERMAL RECEPTOR TYPE-2 OVEREXPRESSED BY MAGLINAT OVARIUM TUMOR

Malignant ovarian tumor is the fourth most common malignancy in woman and the second most gynecological malignancy next to the endometrial carcinoma. High morbidity and mortality rates of the malignant ovarian tumor are mostly caused by the inability to detect an early stage of this malignancy. Almost 65-70% cases of ovarian tumor are found on later stage, with survival rate of about 5-50%. Human Epidermal Receptor (HER-2) is an epidermal growth factor receptor found on the surface of ovarium cells. Interaction between HER-2 with monoclonal antibody (mAb) has been an approach for diagnosis associated with specific interaction which is more targeted on molecule target. Trastuzumab is a humanized mAb which has amino acid structure similar to that of human mAb amino acid. The aim of this study was to analyse binding affinity of interaction between trastuzumab and HER-2 receptor overexpressed by malignant ovarian tumor. The experiments results would be used as a basic consideration for the use of trastuzumab as molecular carrier for specific targeted contrast agent in Magnetic Resonance Imaging (MRI) procedure for maglinant ovarium tumor. This research covered descriptive study of trastuzumab radiolabeling and experimental design of corellational study to evaluate interaction between trastuzumab and HER-2 overexpressed by malignant ovarium tumor cell-lines. The malignant ovarian tumor cell-lines, SKOV-3 provided by LAPTIAB-BBPT, were treated with 125 Iradiolabeled trastuzumab. The in vitro interaction between trastuzumab and HER-2 was analysed by using Scatchard formula. Analysis result gave the value of maximum binding capacity, B max and discotiation constant, K d were 4x10 -7 M and 9,17x10 -9 M respectively. It can be concluded that there was a strong interaction between trastuzumab with HER-2 which was expressed by malignant ovarian tumor. Keywords: Malignant ovarian tumor, HER-2, Monoclonal antibody, Trastuzumab, 125I, , Binding affinity.