Experimental Radioimmunotherapy Of Small Volume Metastasis Of Solid Tumor

Purpose:To study the efficiency and investigate the underlyingmechamism of muiple low dose radioimmunotherapy(RIT) for thetreatment of solid tumor micro-metastases in mice models.Materials and Methods: The mice bearing pulmonary adenoma(LA795)models were treated with ¹⁸⁸Re-CL58. All treatements were initiated atthe 5th day after implanation.Observation was focused on the followingaspects:The tumor controlling effects expressed as of weight loss,tumorburden and metastatic involvement of the organs were compared amongthe groups of different dose and administration groups, and with thechemotherapy group. Drug distributing characteristics were comparedbetween muiple low dose(MLD) RIT group and single high dose(SHD)RIT group by counting the radiation activities in spleen. muscle. lungand kidney at different time points after adminitraion. Cell cycleperturbation and apoptosis induced by RIT were detected with flowcytometry. Telomerase, a significant tumor marker, was also detectedbefore and after RIT.Results: All therapy groups suffered less weight loss than control group,with the MiD RIT grouP the least(p<0.05). No significan difference ofweigh loss existed betWen SHD mT grouP and chemotheraPy grouP.All .theraPy grouPs had less-weighed tumors, also with MLD group theleast. As to the numbers of metastatic foci, MLD RJT grouP had lessthan both chemotheray grouP and SHD group. More imPortan, tumors ofthe MLD RIT grouP absorbed more radiation dose than tumors of SHDgroup after administraion with same dose of radio-labeled antibody.Correspondingly MLD RIT induced more aPoPtosis than SHD RIT did,though no difference of cell cycle pedation occurred betWeen the tWogrouPs. In this model, tUmor cells had very high telomerase activity Butthe activity was significantly brought down by RJT and MLD mT wasmore efficient than SHDmT in doing so.ConcIusion: l. MLD mT was more efficient for the tfeatthent of primaryand metastatic tumors.2.MLD RIT could increase the accumulated radiation dose.3.MLD RJT induced more tUrnor cell to aPoPtose.4.MLD mTwas more efficient for inhibition oftelomerase activop...