Ret oncoproteins represent exploitable targets for therapeutic intervention in MEN2A-associated medullary thyroid carcinoma. The antitumor efficacy and oral bioavailability of RPI-1 support its therapeutic potential.
One approach in the treatment of ovarian cancer patients involves the infusion of autologous T lymphocytes coupled with a bispecific monoclonal antibody MOv18/anti-CD3 (biMAb OC/TR), which recognizes a 38-kDa glycoprotein expressed on ovarian carcinomas and the CD3 T cell receptor. However, little is known about the in vivo biodistribution of injected activated lymphocytes, information that could be obtained by scintigraphic imaging of radiolabelled T cells in order to visualize the migratory pattern. We compared the efficiency, stability and toxicity of technetium-99m hexamethylpropylene amine oxime (HMPAO), indium-111 oxine and fluorine-18 2-fluoro-2-deoxy-d-glucose (FDG) in radiolabelling activated lymphocytes targeted with biMAb OC/TR. The mean labelling efficiencies of 111In-oxine and 18F-FDG using 2.5x10(8) lymphocytes (68% and 64%, respectively) were more than twice that of 99mTc-HMPAO (31%). Retention of the radionuclide in the cell was highest in the case of 111In-oxine labelling (less than 25% of the initial cell-bound activity released after 240 min, as compared with 44% of the 99mTc label in the same period and 45% of 18F radionuclide released after 150 min). None of the three radiolabelling reagents induced any significant alteration in cell viability or immunophenotype. However, both 111In-oxine and 18F-FDG induced a loss of cytotoxic activity of lymphocytes against the ovarian carcinoma cell line IGROV1, and all three radiolabelling reagents caused a significant reduction in the proliferative ability of labelled lymphocytes compared to controls, with cell death occurring after 8-9 days. Radiolabelling with the more stable 111In-oxine reagent using a higher number of lymphocytes (1.4x10(9)) but the same total activity (around 55.5 MBq) resulted in improved labelled T cell viability and proliferative ability, although the mean labelling efficiency decreased (35.8%). Together the data suggest that 111In-oxine at low activity per cell is the most appropriate reagent for radiolabelling activated retargeted T lymphocytes useful for in vivo biodistribution studies.
OBJECTIVE: Multiple endocrine neoplasia type 2 (MEN 2) is a genetic disease characterized by medullary thyroid carcinoma (MTC) associated (MEN 2A and 2B) or not familial MTC (FMTC) with other endocrine neoplasia due to germline RET gene mutations. The prevalence of these rare genetic diseases and their corresponding RET mutations are unknown due to the small size of the study population.\ud
METHODS: We collected data on germline RET mutations of 250 families with hereditary MTC followed in 20 different Italian centres.\ud
RESULTS AND CONCLUSIONS:\ud
The most frequent RET amino acid substitution was Val804Met (19.6%) followed by Cys634Arg (13.6%). A total of 40 different germline RET mutations were present. Six families (2.4%) were negative for germline RET mutations. The comparison of the prevalence of RET germline mutations in the present study with those published by other European studies showed a higher prevalence of Val804Met and Ser891Ala mutations and a lower prevalence of Leu790Phe and Tyr791Phe (P<0.0001). A statistically significant higher prevalence of mutations affecting non-cysteine codons was also found (P<0.0001). Furthermore, the phenotype data collection showed an unexpected higher prevalence of FMTC (57.6%) with respect to other MEN 2 syndromes (34% MEN 2A and 6.8% of MEN 2B). In conclusion, we observed a statistically significant different pattern of RET mutations in Italian MEN 2 families with respect to other European studies and a higher prevalence of FMTC phenotype. The different ethnic origins of the patients and the particular attention given to analysing apparently sporadic MTC for RET germline mutations may explain these findings
Despite efforts to develop new, highly specific antibodies, the evaluation of this marker is still flawed by analytical inaccuracy. hCT values are widely dispersed depending on the method used for marker measurement; as a consequence, patient classification according to the hCT cutoff value is still dependent on the assay used.
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