Therapeutic Characterization of ^(131)I-Labeled Humanized Anti-B7-H3 Antibodies for Radioimmunotherapy for Glioblastoma

B7 homolog 3(B7-H3)has attracted much attention in glioblastoma(GBM)radioimmunotherapy(RIT)due to its abnormally high expression on tumor cells.In this study,we report that two specific humanized anti-human B7-H3 antibodies(hu4G4 and hu4H12)derived from mouse anti-human B7-H3 antibodies that were generated by computer-aided design and exclusively recognize membrane expression of B7-H3 by human glioma cells,Hu4G4 and hu4H12 were radiolabeled with^(89)Zr for RIT antibody screening.Micro-positron emission tomography(PET)imaging,biodistribution and pharmacokinetic(PK)analyses of^(89)Zr-labeled antibodies were performed in U87-xenografted models.^(125)I labelling of the antibodies for single-photon emission computed tomography(SPECT)imaging was also used to investigate the biological behavior of the antibodies in vivo.Fu rthermore,the pharmacodynamic(PD)of the^(131)Ilabeled antibodies were evaluated in U87-xenografted mice and GL261 Red-FLuc-B7-H3 in situ glioma tumor models.Micro-PET imaging and biodistribution analysis with a gamma counter showed that^(89)Zr-deferoxamine(DFO)-hu4G4 had higher tumor targeting performance with lower liver uptake than^(89)Zr-DFO-(hu4H12,immunoglobulin G(IgG)).The biodistribution results of^(125)I-SPECT imaging were similar to those of^(89)Zr-PET imaging,though the biodistribution in long bone joints and the thyroid varied.The PD analysis results indicated that^(131)I-hu4G4 had an excellent therapeutic effect and high safety with no apparent toxicity.Interestingly,^(131)I-hu4G4 improved the tumor vasculature in tissues with higher expression of collagen typeⅣand platelet-derived growth factor receptorβ(PDGFR-β)compared with control treatment,as determined by immunofluorescence(IF),which contributed to inhibiting tumor growth.Taken together,our data indicate that hu4G4 exhibits good tumor targeting and specificity,achieves low nonspecific concentrations in normal tissues,and has acceptable PK characteristics.^(131)I-hu4G4 also exerts effective antitumor effects with an ideal safety profile.Therefore,we expect hu4G4 to be an excellent antibody for the development of GBM RIT.

Activity estimation in radioimmunotherapy using magnetic nanoparticles

Objective： Estimation of activity accumulated in tumor and organs is very important in predicting the response of radiopharmaceuticals treatment. In this study, we synthesized ~77Lutetium （177Lu）-trastuzumabiron oxide nanoparticles as a double radiopharmaceutical agent for treatment and better estimation of organ activity in a new way by magnetic resonance imaging （MRI）. Methods： ^177Lu-trastuzumab-iron oxide nanoparticles were synthesized and all the quality control tests such as labeling yield, nanoparticle size determination, stability in buffer and blood serum up to 4 d, immunoreactivity and biodistribution in normal mice were determined. In mice bearing breast tumor, liver and tumor activities were calculated with three methods： single photon emission computed tomography （SPECT）, MRI and organ extraction, which were compared with each other. Results： The good results of quality control tests （labeling yield： 61%±2%, mean nanoparticle hydrodynamic size： 41±15 nm, stability in buffer： 86%±5%, stability in blood serum： 80%±3%, immunoreactivity： 80%±2%） indicated that ^177Lu-trastuzumab-iron oxide nanoparticles could be used as a double radiopharmaceutical agent in mice bearing tumor. Results showed that ^177Lu-trastuzumab-iron oxide nanoparticles with MRI had the ability to measure organ activities more accurate than SPECT. Conclusions： Co-conjugating radiopharmaceutical to MRI contrast agents such as iron oxide nanoparticles may be a good way for better dosimetry in nuclear medicine treatment.

Avidin-biotin system pretargeting radioimmunoimaging and radioimmunotherapy and its application in mouse model of human colon carcinoma

AIM: To evaluate the multi-step pretargeting radioimmunoimaging (RII) and radioimmunotherapy (RIT) in nude mice bearing human colon carcinoma with avidin-biotin system labeled with 153Sm.METHODS: Two- and three-step strategies for avidinbiotin system pretargeting techniques were established.In a three-step procedure, human colon carcinoma bearing nude mice were first injected with biotinylated monoclonal antibody (McAb-Bt) followed by cold avidin (Av) 48 h later and then 153Sm-DB2 24 h thereafter;whereas the twostep procedure consisted of injection of 153Sm-SA 48 h after pretargeting with biotinylated anti-CEA monoclonal antibody (CEA McAb-Bt). SPECT imaging and biodistribution were performed at 4, 24, 48, or 72 h after injection of 153Sm-labeled compounds. Five groups of nude mice subcutaneously grafted with human colon carcinoma were treated 3 d after grafting. One group received the injection with 100 μg CEA McAb-Bt followed by cold avidin (80 μg)after 2 d and 11.1 MBq 153Sm-DB2 after 1d. Four control groups were treated respectively with 11.1 MBq 153SmCEA McAb, 11.1 MBq 153Sm-nmIgG, 11.1 MBq 153Sm-DB2,100 Μl normal saline. Toxicity was evaluated by changes of leukocyte count, and the efficacy by variation in tumor volume. Histological analyses of tumors were performed.RESULTS: The three-step procedure allowed faster blood clearance and yielded higher tumor blood ratios (5.76 at4 h and 12.94 at 24 h) of the 153Sm-DB2. The tumor was clearly visualized at 4 h in y-imaging after the injection of 153Sm-DB2, while a significant accumulation of 153Sm-SA in the tumor was observed only 24 h after the injection and tumor blood ratios at 4 and 24 h were 1.00 and 2.03,respectively, in the two-step procedure. Pretargeting RIT and 153Sm-CEA McAb had a strong tumor-inhibiting effect.The tumor inhibitory rate was 80.67% and 78.44%,respectively, five weeks after therapy. Histopathological evidence also indicated radioactive damage in tumor tissues as necrosis of tumor cells, while in the other organs such as liver and kidney no radioactive damage was observed. Leukocyte counts showed significant decrease after treatment in groups of 153Sm-CEA Mc Ab and 153SmnmIgG.CONCLUSION: The two kinds of pretargeting strategies can elevate the target-to-nontarget ratio, decrease the blood background and shorten the imaging time compared to 153Sm-CEA McAb. Three-step pretargeting RIT is as efficient as 153Sm-CEA Mc Ab, but markedly less toxic. This study provides experimental evidence for the clinical application of pretargeting RII and RIT.

Avidin chase reduces side effects of radioimmunotherapy in nude mice bearing human colon carcinoma

AIM: To evaluate the influence of avidin chase on the side effects of radioimmunotherapy (RIT) in nude mice bearing human colon carcinoma and therapeutic outcome.METHODS: Purified anti-CEA monoclonal antibody (McAb)was biotinylated with NHS-biotin, and then radiolabeled with 188Re by the direct method. 188Re-labeledbiotinylated anti-CEA McAb (188Re-CEA McAb-Bt) was intravenously injected followed by intravenous injection of avidin after 24 h. SPECT imaging and biodistribution study were performed at 28-48 h after the injection of 188Re-CEA McAb-Bt. Three groups of nude mice subcutaneously grafted with human colon carcinoma were treated 7 d after the graft. Mice in the avidin chase group received intravenous injection of 188Re-CEA McAb-Bt (11.1 MBq/20 μg) followed by intravenous injection of cold avidin (80 μg) after 24 h. Mice in the control group (treated group without avidin chase) only received the injection of 188Re-CEA McAb-Bt (11.1 MBq/20 μg), another control group (non-treated group) only received 0.1 mL normal saline solution. Toxicity was evaluated on the basis of change of body weight and peripheral WBC counts, and therapy effects were determined by variation in tumor volume. Histological analysis of tumors was also performed.RESULTS: Avidin chase markedly accelerated the clearance of 188Re-CEA McAb-Bt from the blood and normal tissues. The tumor uptakes of 188Re-CEA Mc Ab-Bt at 28 h were 5.90 and 6.42% ID/g, respectively, in chase group and in non-chase group, while the tumor-to-background (T/NT) ratios were 3.19 and 0.56, respectively. The tumor uptake was slightly decreased by avidin chase, but the T/NT ratios were increased. In treated groups the growth rate of body weight and the number of WBC decreased after injection of 188Re-CEA McAb-Bt, and the WBC counts recovered earlier in the group with avidin chase than in the group without avidin chase. Compared to the nontreated group, treated groups with and without avidin chase showed significant anti-tumor effects.CONCLUSION: Avidin chase can effectively reduce the side effects of RIT, and improve therapeutic efficacy.

RADIOIMMUNOTHERAPY IN TREATMENT OF UNRESECTABLE HEPATOMA－A REPORT OF 43 CASES

Forty-three patients with surgically verified unresectable hepatoma had been treated by radioimmunotherapy(RIT)using￣(131)I antiferritin antibidy as a part of multimodality treatment during 1985 - 1990.The shortand long-term responses were compared with those in control group of 39 patients with unresectable hepatoma receiving conventional multimodality treatment in the same period.The rates of the tumor shrinkage,serum AFP decline and sequence resction were 67. 4% (29/43),69.6%(16/23)and 30.2%(13/43)respectively,which were significantly higher than those in contrul group[23.1%(15/39),40.0%(8/20)and 10.3%(4/39),respectively].The 1-,3- and 5-year survival rates were 61.5%,40.4%and 35.4%,respectively,for the RIT group,and 51.2%,20.1% and 15.5% ,respectrely,for the control group.The tumor size,dose of RIT and sequence resection were identified as significant factors (P=0.005,0.025 and 0.006,respectively, with Cox analysis model in 13 influencing factors.The results indicate that RIT was an effective one in multimodality treatment,particularly in the conversion of unresectable to resectable tumor.

CHANGES OF SERUM ALPHA FETOPROTEIN BEFORE AND AFTER RADIOIMMUNOTHERAPY IN PATIENTS WITH HEPATOCELLULAR CARCINOMA

Thirtytwo patients with surgically verified unresectable table hepatocellular carcinoma (HCC) have been treated by radioimmunotherapy (RIT) using intrahepatic arterial administration of￣(131)I anti HCC monoclonal antibody (Hepama1) combined with hepetic artery ligation. Twenty of them had abnormal serum alpha fetoprotein (AFP,>20 ng/ml). Single photon emission computed tomography (SPECT) scan and quantitative assay of AFP were performed after RIT. The results revealed that when the tumor to liver ratio (T/L) was higher than 3.5 (Group A , n =3) , the serum AFP level declined markedly and then kept in stable for a tongtime; when the T/L ratio was less than 1.2 (Group C ,n=5), the serum AFP level did not change evidently within 2 months postinfusion; while the T/L ratio was between 1. 2 3. 5 (Group B, n= 12) , the serum AFP level increased transiently and then decreased within 2 4 weeks postinfusion. Sequentiat resection was achieved in all of the 3 patients of Group A, in 6 patients (50%) of Group B, and none in Group C. The correlation of serum AFP and effective treatment demonstrates the usefulness of this oncofetal protein marker as an indicator of neoplastic activity for HCC and T/L ratio might be a good indicator to predict tumor response to RIT in patients with

Combined treatment of pancreatic cancer xenograft with 90Y-ITGA6B4-mediated radioimmunotherapy and PI3K/m TOR inhibitor

AIM To investigate the therapeutic effect of combined integrin α6β4-targeted radioimmunotherapy(RIT) and PI3 K/m TOR inhibitor BEZ235 in a pancreatic cancer model.METHODS Phosphorylation of Akt, m TOR, the downstream effectors eukaryotic initiation factor 4 E binding protein 1(4 EBP1) and S6 ribosomal protein(S6) were evaluated in Bx PC-3 human pancreatic cancer cells treated with Yttrium-^(90)(^(90) Y) labeled anti-integrin α6β4 antibody(ITGA6 B4) and BEZ235 by western blotting. The cytotoxic effect of BEZ235 was investigated using a colony formation assay. Therapeutic efficacy enhancement by oral BEZ235 administration was assessed using mice bearing Bx PC-3 xenograft tumors. Tumor volume measurements and immunohistochemical analyses(cell proliferation marker Ki-67, DNA damage marker p-H2 AX and p-4 EBP1 staining) of tumors were performed for evaluation of combined treatment with ^(90) Y-ITGA6 B4 plus BEZ235, or each arm alone.RESULTS We found that phosphorylation of Akt(p-Akt), 4 EBP1(p-4 EBP1) and S6(p-S6) was inhibited by BEZ235. Colony formation in Bx PC-3 cells was additively suppressed by the combination of ^(90) Y-ITGA6 B4 and BEZ235. Pretreatment with BEZ235 before ^(90) Y-ITGA6 B4 exposure resulted in significant reduction of cells plating efficiency(PE)(0.54 ± 0.11 vs 2.81 ± 0.14 with 185 k Bq/m L ^(90) Y-ITGA6 B4 exposure, P < 0.01; 0.39 ± 0.08 vs 1.88 ± 0.09 with 370 k Bq/m L ^(90) Y-ITGA6 B4 exposure, P < 0.01) when 5 × 10~3 cells per dish were plated. In vivo, the combined treatment with ^(90) Y-ITGA6 B4 plus BEZ235 enhanced the inhibition of tumor growth and statistically significant differences of relative tumor volume were observed for 27 d after the treatment start date when compared with the ^(90) Y-ITGA6 B4 single injection treatment(1.03 ± 0.38 vs 1.5 ± 0.15 at Day 27, P < 0.05), and for 41 d when compared with the BEZ235 treatment alone(1.8 ± 0.7 vs 3.14 ± 1.19 at Day 41, P < 0.05). Tumors from treatment groups showed reduction in volumes, decreased Ki-67-positive cells, increased p-H2 AX-positive cells and decreased p-4 EBP1 expression. CONCLUSION The therapeutic efficacy of ^(90) Y-ITGA6 B4-RIT can be improved by combining with dual PI3 K and m TOR inhibitor, BEZ235, in a pancreatic cancer model suggesting potential clinical application.

Near-Infrared Light-Responsive Nitric Oxide Delivery Platform for Enhanced Radioimmunotherapy

Radiotherapy(RT)is a widely used way for cancer treatment.However,the efficiency of RT may come with various challenges such as low specificity,limitation by resistance,high dose and so on.Nitric oxide(NO)is known a very effective radiosensitizer of hypoxic tumor.However,NO cannot circulate in body with high concentration.Herein,an NIR light-responsive NO delivery system is developed for controlled and precisely release of NO to hypoxic tumors during radiotherapy.Tert-Butyl nitrite,which is an efficient NO source,is coupled to Ag2S quantum dots(QDs).NO could be generated and released from the Ag2S QDs effectively under the NIR irradiation due to the thermal effect.In addition,Ag is also a type of heavy metal that can benefit the RT therapy.We demonstrate that Ag2S NO delivery platforms remarkably maximize radiotherapy effects to inhibit tumor growth in CT26 tumor model.Furthermore,immunosuppressive tumor microenvironment is improved by our NO delivery system,significantly enhancing the anti-PD-L1 immune checkpoint blockade therapy.100% survival rate is achieved by the radio-immune combined therapy strategy based on the Ag2S NO delivery platforms.Our results suggest the promise of Ag2S NO delivery platforms for multifunctional cancer radioimmunotherapy.

FACTORS INFLUENCING THE EFFECT OF RADIOIMMUNOTHERAPY ON LIVER CANCER

Factors influencing the therapeutic effect of radiolmmunotherapy with 131I labeled anti- human hepa-tocellular carcinoma (HCC) ferritin antibody (131I -FtAb) on thirty three patients with surgically proven unresectable HCC were studied. Multi- variable analysis with Cox' s regression model revealed that the statistically sig-nifieant factors include tumor size, activity of 131I administered each time and the second-look resection. Survival of patients with tumor diameter less than 10 cm was higher than that of patients with tumor diameter more than 10 cm (1-year survival; 84% versus 50%) 3-year survival; 63% versus 9% ). Patients administered with 5. 55×108 Bq to 9. 25× 10(?) of 131I-FtAb each time yielded better effect than those administered with more than 9. 25×108 Bq of 131I -FtAb (1-year, survival: 86% ver- sus 55%; 3-year survival: 50% versus 18%). When tumor shrank, patients underwent second-look resection had a higher survival than those without receiving second- look resection (1- year survival, 80%versus 66 %; 3-year survival; 80% versus 11%).

核素标记不同性质单抗瘤内注射治疗大肠癌的研究

目的 :探讨核素标记抗细胞膜抗原单克隆抗体联合核素标记抗细胞核单克隆抗体瘤内注射治疗荷人大肠癌裸鼠移植瘤的可行性和优越性 ,为临床应用核素标记多种不同性质的单克隆抗体进行放射免疫治疗提供实验依据。方法 :在裸鼠荷人大肠癌Lovo移植瘤生长至 1cm左右时 ,瘤内分别或同时注射13 1I标记的抗大肠癌细胞膜抗原CL3 单克隆抗体 (13 1I CL3 )和13 1I标记人 /鼠嵌合抗细胞核的单克隆抗体chTNT(13 1I chTNT) ,治疗后行SPECT显像观察标记抗体在肿瘤内的浓聚 ,并进行疗效观察。结果 :研究发现 2种标记抗体联合应用组的肿瘤抑制率为 82 .3% ,明显高于13 1I CL3 IT组的 5 7.9%或13 1I chTNT组的 5 3.1% ,联合应用组标记抗体在肿瘤组织 /非肿瘤组织内的放射活度比值 (T/NT值 )大于单独应用组。结论 :13 1I CL3 联合13 1I chTNT瘤内注射放射免疫治疗可增加标记抗体在肿瘤组织内的浓聚 ,并能提高放射免疫治疗效果。

^(188)Re-BAC_5对鼻咽癌细胞影响的实验研究

采用直接标记法制备188Re-BAC5,并测定标记物的免疫活性,应用噻唑蓝(MTT)法观察188Re-BAC5对体外单层培养的鼻咽癌细胞(CNE-2)的抑制作用。建立鼻咽癌(NPC)肿瘤多细胞微球模型,观察188Re-BAC5对微球生长的抑制和破坏作用。对照组为188Re-BSA、188ReO4。结果显示:188Re-BAC5的标记率在80%以上,标记后的免疫活性分数为61%±15%。MTT法结果表明,188Re-BAC5组的抑瘤率比对照组明显提高(P<0.05);在肿瘤多细胞微球的抑制实验中,188Re-BAC5对微球生长有强烈的抑制和破坏作用,疗效明显优于对照组。本实验提示,188Re-BAC5有可能在对人鼻咽癌的放射免疫治疗中起到良好的作用。

“双弹头”抗AFP抗体对肝癌导向综合治疗的实验和临床研究

为增强导向治疗的“弹头”杀伤力，提高肝癌导向综合治疗的疗效，对马抗人ＡＦＰ抗体进行了１３１Ⅰ和丝裂霉素（ＭＭＣ）双标记，制备同时携带１３１Ⅰ和ＭＭＣ的“双弹头”马抗人ＡＦＰ抗体（１３１Ⅰ－ＡＦＰＡｂ－ＭＭＣ）。荷人肝癌裸鼠的定位显像和抑癌率实验显示１３１Ⅰ－ＡＦＰＡｂ－ＭＭＣ具有良好的定位显像作用，抑癌率达７３．５％，明显高于对照组（Ｐ＜０．０５）。２２例配对的中晚期原发性肝癌患者的“双弹头”导向综合治疗结果：治疗组的有效率（ＣＲ＋ＰＲ＋ＭＲ）为６３．２％明显高于对照组（３１．８％），Ｐ＜０．０５；治疗组的１年生存率（５２．６％）亦明显高于对照组（２２．７％）Ｐ＜０．０５，且无严重毒副作用。表明：１３１Ⅰ－ＡＦＰＡｂ－ＭＭＣ的“双弹头”

^(131)碘肿瘤细胞核人鼠嵌合单抗肺癌内直接注射后体内的生物学分布

目的研究肺癌瘤内直接注射131I-chTNT后患者体内分布状况。方法经病理组织学确诊的原发性肺癌患者11例,根据CT定位,单次瘤内直接注射131I-chTNT18.5～37MBq/cm3后,多时点测量血、尿放射性。应用HPLC法检测131I-chTNT在体内的稳定性和代谢情况。采用连续显像法估算全身、各主要脏器和肿瘤的放射性,并转换为注射剂量百分率(%ID),以观察131I-chTNT在体内的分布。结果所有11例患者HPLC检测结果显示,注射后24、48、72、96h内血清中131I-chTNT均以原形存在,原形含量达100%。经计算机拟合,血清药-时曲线符合静脉外给药二室模型,T1/2kα(0.89±0.17)h,T1/2β(86.88±25.97)h。游离131I是尿内131I-chTNT的唯一代谢产物,264h累计尿排泄量为注射量的(58.37±17.45)%。瘤内给药后30min,瘤内131I-chTNT量为(51.05±8.41)%ID,瘤/肺比值(T/N)高达(63.87±25.71)。264h时瘤内131I-chTNT残留(3.47±3.27)%ID,T/N为(9.61±11.00)。全身主要器官中,放射性主要集中在肺、肝、心、肾、脾和甲状腺中。结论131I-chTNT瘤内直接注射后在瘤内停留时间较长,有利于肿瘤治疗。

肝癌^(188)Re放射免疫治疗的实验研究

目的：研究新型核素188Re标记的抗人肝癌单抗片段HAb18 F（ab′）2对荷肝癌移植瘤裸鼠的抑瘤效应。方法：建立荷人肝癌移植瘤裸鼠模型。选择肿瘤体积为（30～150）mm3的动物随机分5组，其中3组分别尾静脉注射188Re－HAb18 F（ab′）2 3．7、11．1和18．5MBq，给药2次，观察动物体重和肿瘤体积变化。处死动物，摘取瘤体，石蜡包埋，进行HE染色。结果：3组剂量均有不同程度的抑瘤作用，且随着剂量的增加，抑瘤效应增加。低剂量组和中剂量组动物平均体重和生理盐水对照组相比无显著性差异(P＞0．05)。组织学检查表明，随着剂量的增加，肿瘤细胞核形态发生明显的变化，从凝固、核碎裂直至溶解。结论：188Re－HAb18 F（ab′）2是一种新型核素的肝癌导向治疗剂，具有潜在的临床应用前景，本文的研究可为其过渡到临床研究提供参考依据。

^(131)I-肿瘤细胞核人鼠嵌合单抗肿瘤治疗内照射吸收剂量估算

目的 估算1 31 I 肿瘤细胞核人鼠嵌合单克隆抗体 (chTNT)肿瘤治疗中肿瘤和主要器官内照射吸收剂量。方法 9例肿瘤患者 ,单次静脉注射1 31 I chTNT按体重 (2 9 6± 3 7)MBq kg后测量各时间点血、尿样放射性 ,并采用连续 (配对 )显像结合CT扣除周围组织本底的方法估算各时间点全身、肿瘤及主要器官放射性 ;将原始数据转换为百分注射剂量 (%ID) ,用一室或二室模型拟合时间 放射性曲线 ,求单位累积活度 ,采用医用内照射照射吸收剂量 (MIRD)方法将其输入Mirdose 3软件 ,求得全身、肿瘤和各主要器官的平均总吸收剂量。结果 肿瘤平均总吸收剂量为 (8 2 8± 2 6 5 )Gy ,瘤 非瘤比值为 3 95± 1 5 5。结论 该注射剂量难以满足抑制肿瘤生长的要求。为姑息性抑制肿瘤生长 ,有必要多次重复给药。

^(131)I标记人源抗HBsAg Fab对荷人肝癌裸鼠的放射免疫治疗

目的 1 3 1 I标记人源抗 HBs Ag Fab经腹腔注射治疗荷人肝癌裸鼠移植瘤 ,与 1 3 1 I- S1 0 2 比较 ,评价其作为肝癌放射免疫治疗 (RIT)的可能性。方法 荷瘤裸鼠分为 4组分别经腹腔注射不同放射剂量的 1 3 1 I-抗 HBs Ag Fab、1 3 1 I- S1 0 2 、1 3 1 I-无关 Fab及 PBS。按一定时间间隔作组织分布和血液清除速率测定 ,继续观察 4周 ,以外周血白细胞和血小板数量变化行毒性分析 ,计算各组肿瘤生长抑制率。结果 1 3 1 I-抗HBs Ag Fab被肿瘤区的摄取和在血液中清除速率均明显快于 1 3 1 I- S1 0 2 ,同等剂量下 ,前者抗肿瘤疗效略低 ,但血液毒性明显减轻。结论 人源抗 HBs Ag Fab具有良好的免疫结合活性 ,核素标记后用于 RIT,能够被肿瘤快速摄取并在体内正常组织中快速清除 ,毒性减低 ,具有良好的抗肿瘤疗效 ,是原发性肝癌

^(35)S标记SZ39导向治疗胶质瘤的实验研究

目的制备纯β射线放射免疫治疗制剂３５Ｓ标记单克隆抗体（ＭＡｂ）ＳＺ３９，并证实其对胶质瘤的特异杀伤作用。方法３５Ｓ以碳二亚胺法标记ＳＺ３９。采用ＭＴＴ法，以人脑胶质瘤细胞系ＳＨＧ４４为靶细胞，检测３５ＳＳＺ３９及其对照组３５ＳｎＩｇＧ、３５Ｓ加ＳＺ３９、３５Ｓ持续作用组的细胞杀伤率，求得５０％细胞抑制浓度；以荷瘤鼠为对象，以３５ＳｎＩｇＧ及ＰＢＳ为对照组，根据公式求得３５ＳＳＺ３９肿瘤抑制率；并以流式细胞计数仪分析３５ＳＳＺ３９的抑瘤效应。结果３５ＳＳＺ３９细胞杀伤力与３５Ｓ持续作用相近，较３５ＳｎＩｇＧ强４２倍，较３５Ｓ加ＳＺ３９强４０倍。１０３６ＭＢｑ３５ＳＳＺ３９对肿瘤可产生抑制作用，阻滞肿瘤生长１周左右，给药后２６ｄ，抑制率达５０％。经３５ＳＳＺ３９治疗后肿瘤细胞ＤＮＡ合成受抑，Ｓ期细胞蓄积，Ｇ１期细胞受阻，有细胞周期同步化趋势。３５ＳＳＺ３９有抑瘤作用，但对骨髓无明显毒副作用。结论３５ＳＳＺ３９能选择性杀伤胶质瘤细胞。

^(188)Re-CL58、^(131)I-chTNT放射免疫治疗的临床研究

目的:比较多次小剂量与大剂量放射免疫治疗(RIT)对实体瘤的初步临床疗效及不良反应。方法:采用多次小剂量188Re-CL58及大剂量131I-chTNT对临床病例治疗。用脱氧葡萄糖(FDG)-正电子发射断层扫描(PET)显像方法及动态观察血清中肿瘤标志物变化监测疗效。用间接免疫荧光法评价RIT对T淋巴细胞亚群的影响。观察其对造血系统和肝、肾等器官的不良反应。结果:多次小剂量188Re-CL58治疗后病灶部位的FDG摄取SUV值(Standarduptakevalue)均下降,对于小转移灶SUV下降更明显,且血清CEA等水平均下降,而大剂量131I-chTNT组CEA下降不及多次小剂量组明显。多次小剂量RIT后外周血CD4+细胞升高、CD8+细胞减少以及CD4+/CD8+比例升高,而大剂量RIT后CD4+/CD8+比例降低。大剂量组比多次小剂量组对白细胞、血小板、血色素的抑制明显,结论:多次小剂量188Re-CL58治疗效果优于大剂量131I-chTNT,且能解除肌体的免疫抑制;多次小剂量188Re-CL58治疗对造血系统抑制小于大剂量131I-chTNT。

^(131)I-组合单克隆抗体局部放射免疫导向治疗肝癌的临床观察

探讨13 1 I标记组合单克隆抗体S10 2、T9、CL 3(Cocktail法)局部导向治疗肝癌的近期疗效、毒副反应。采用IODO GEN法标记13 1I McAb,B超引导下经皮穿刺肿瘤局部注射 ,治疗 116例中晚期原发性肝癌 ,用量每次 5 0～ 70mCi。结果显示 ,本治疗有效率 (CR +PR) 2 9 3%,总有效率(CR +PR +MR) 5 3 4 %,一年生存率 38 2 %,中位生存期 34 7周 ,中位疾病进展期 12周。表明13 1I标记组合单克隆抗体局部导向治疗原发性肝癌属于微创手术 ,经济、疗效确切、毒副反应小。

^(131)I-Herceptin的制备、质控及在新西兰兔的生物分布

目的探讨131I-Herceptin的免疫活性、生物分布及代谢规律,为乳腺癌的131I-Herceptin放射免疫治疗提供实验依据。方法①采用Iodogen法对Herceptin进行131I标记,以HPLC法测定放射化学纯度(RCP)。以与BT-474细胞结合率(BR)鉴定131I-Herceptin的免疫活性。②按74 MBq/kg.b.w.对3只新西兰兔注射131I-Herceptin,注射后3 h及第1、3、5天进行透射CT显像。以肌肉为参照,计算各脏器放射性计数比值(O/M)。③第5天处死动物,取血、心、肺、肝、肾等脏器,计算每克组织摄取分数(ID%/g),对结果进行统计分析。结果131I-Herceptin的标记率为93%,RCP为95%,在BT-474细胞结合率为(36.9±4.7)%。注射131I-Herceptin后不同时间均以心脏、肺、肝浓聚显著,肌肉、肠影像稀疏。随时间延迟,心影逐渐稀疏,肝脏影像浓聚。注射后3 h,心脏O/M值显著高于肺及肝、肾、肠等脏器。随时间延迟,心脏O/M值于注射后1 d显著降低(t=10.817,P<0.001),第3、5天亦显著降低,肝脏O/M值在第1、3、5天均比注射后3 h显著下降。每克组织的摄取分数以血液最高,为(11.3 ID/g)%、肝为(2.8 ID/g)%、心肌仅为(1.8 ID/g)%。结论131I-Herceptin的免疫活性高。机体分布以血液、肝、肾为主,心肌摄取量低。