188Re-SSS lipiodol: radiolabelling and biodistribution following injection into the hepatic artery of rats bearing hepatoma

188Re-SSS Lipiodol Radioembolization in HCC Patients: Results of a Phase 1 Trial (Lip-Re-01 Study)

BACKGROUND

Despite the wide development of ⁹⁰Y-loaded microspheres, ¹⁸⁸Re-labeled lipiodol is still being used for radioembolization of hepatocellular carcinoma (HCC). However, the use of this latter compound is limited by in vivo instability. This study sought to evaluate the safety, bio-distribution, and response to ¹⁸⁸Re-SSS lipiodol, a new and more stable compound.

METHOD

Lip-Re-01 was an activity-escalation Phase 1 study involving HCC patients progressing after sorafenib. The primary endpoint was safety based on Common Terminology Criteria for Adverse Events (AEs) of Grade ≥3 within 2 months. Secondary endpoints included bio-distribution assessed by scintigraphy quantification from 1 to 72 h, tumor to non-tumor uptake ratio (T/NT), as well as blood, urine and feces collection over 72 h, dosimetry, and response evaluation (mRECIST).

RESULTS

Overall, 14 heavily pre-treated HCC patients were treated using a whole liver approach. The mean injected activity was 1.5 ± 0.4 GBq for activity Level 1 (n = 6), 3.6 ± 0.3 GBq for Level 2 (n = 6), and 5.0 ± 0.4 GBq for Level 3 (n = 2). Safety was acceptable with only 1/6 of Level 1 and 1/6 of Level 2 patients experiencing limiting toxicity (one liver failure; one lung disease). The study was prematurely discontinued unrelated to clinical outcomes. Uptake occurred in the tumor, liver, and lungs, and only sometimes in the bladder. The T/NT ratio was high with a mean of 24.9 ± 23.4. Cumulative urinary elimination and fecal eliminations at 72 h were very low, 4.8 ± 3.2% and 0.7 ± 0.8%, respectively. Partial response occurred in 21% of patients (0% in the first activity level; 37.5% in the others).

CONCLUSION

The high in vivo stability of ¹⁸⁸Re-SSS lipiodol was confirmed, resulting in encouraging responses for a Phase 1 study. As the 3.6 GBq activity proved to be safe, it will be used in a future Phase 2 study.

Mechanism of Action, Pharmacokinetics, Efficacy, and Safety of Transarterial Therapies Using Ethiodized Oil: Preclinical Review in Liver Cancer Models

PURPOSE

To systematically review mechanism of action, pharmacokinetics (PKs), efficacy, and safety of ethiodized oil-based locoregional therapy (LRT) for liver cancer in preclinical models.

MATERIALS AND METHODS

A MEDLINE search was performed from 1988 to 2016. Search terms included hepatocellular carcinoma (HCC), HCC, liver-cell carcinoma, liver, hepatic, hepatocarcinoma, transarterial or chemoembolization, TACE, animal, Lipiodol, Ethiodol, iodized oil, and/or poppy-seed oil. Inclusion criteria were: publication in a peer-reviewed journal, an accepted animal model, and PK/safety/efficacy data reported. Exclusion criteria were: inadequate PK, safety, or efficacy data; anticancer drug name/dose not available; and article not in English. Outcomes included intratumoral anticancer drug uptake, PKs, tolerance, tumor response, and survival.

RESULTS

Of 102 identified articles, 49 (49%) met the inclusion criteria. Seventeen, 35, and 2 articles used rat, rabbit, and pig models. Mechanism of action was investigated in 11 articles. Eleven articles reported drug uptake, PK, and tolerance data, showing 0.5%-9.5% of injected chemotherapy dose in tumor. Tumor-to-liver drug distribution ratios were 2-157. Toxicology data across 6 articles showed transient liver laboratory level elevations 1 day after LRT. There was no noteworthy liver or extrahepatic histologic damage. Nine articles reported tumor response, with 0%-30% viable tumor and -10% to -38% tumor growth at 7 days after LRT. Two articles reported survival, showing significantly longer survival after LRT vs untreated controls (56/60 d vs 33/28 d). Several articles described ethiodized oil mixed with radiopharmaceutical (n = 7), antiangiogenic (n = 6), gene (n = 6), nanoembolic (n = 5), immune (n = 2), or other novel (n = 1) agents.

CONCLUSIONS

Animal studies show preferential tumor uptake of anticancer agent, good hepatic/systemic tolerance, high tumor response, and enhanced survival after ethiodized oil-based LRT.

Tumor uptake of hollow gold nanospheres after intravenous and intra-arterial injection: PET/CT study in a rabbit VX2 liver cancer model

PURPOSE

This study was designed to investigate the intratumoral uptake of hollow gold nanospheres (HAuNS) after hepatic intra-arterial (IA) and intravenous (IV) injection in a liver tumor model.

MATERIALS AND METHODS

Fifteen VX2 tumor-bearing rabbits were randomized into five groups (n = 3 in each group) that received either IV (64)Cu-labeled PEG-HAuNS (IV-PEG-HAuNS), IA (64)Cu-labeled PEG-HAuNS (IA-PEG-HAuNS), IV cyclic peptide (RGD)-conjugated (64)Cu-labeled PEG-HAuNS (IV-RGD-PEG-HAuNS), IA RGD-conjugated (64)Cu-labeled PEG-HAuNS (IA-RGD-PEG-HAuNS), or IA (64)Cu-labeled PEG-HAuNS with lipiodol (IA-PEG-HAuNS-lipiodol). The animals underwent PET/CT 1 h after injection, and uptake expressed as percentage of injected dose per gram of tissue (%ID/g) was measured in tumor and major organs. The animals were euthanized 24 h after injection, and tissues were evaluated for radioactivity.

RESULTS

At 1 h after injection, animals in the IA-PEG-HAuNS-lipiodol group showed significantly higher tumor uptake (P < 0.001) and higher ratios of tumor-to-normal liver uptake (P < 0.001) than those in all other groups. The biodistribution of radioactivity 24 h after injection showed that IA delivery of PEG-HAuNS with lipiodol resulted in the highest tumor uptake (0.33 %ID/g; P < 0.001) and tumor-to-normal liver ratio (P < 0.001) among all delivery methods. At 24 h, the IA-RGD-PEG-HAuNS group showed higher tumor uptake than the IA-PEG-HAuNS group (0.20 vs. 0.099 %ID/g; P < 0.001).

CONCLUSION

Adding iodized oil to IA-PEG-HAuNS maximizes nanoparticle delivery to hepatic tumors and therefore may be useful in targeted chemotherapy and photoablative therapy. PET/CT can be used to noninvasively monitor the biodistribution of radiolabeled HAuNS after IV or IA injection.

Rhenium-188 production in hospitals, by w-188/re-188 generator, for easy use in radionuclide therapy

Rhenium-188 (Re-188) is a high energy β-emitting radioisotope obtained from the tungsten-188/rhenium-188 (W-188/Re-188) generator, which has shown utility for a variety of therapeutic applications in nuclear medicine, oncology, and interventional radiology/cardiology. Re-188 decay is accompanied by a 155 keV predominant energy γ-emission, which could be detected by γ-cameras, for imaging, biodistribution, or absorbed radiation dose studies. Its attractive physical properties and its potential low cost associated with a long-lived parent make it an interesting option for clinical use. The setup and daily use of W-188/Re-188 generator in hospital nuclear medicine departments are discussed in detail. The clinical efficacy, for several therapeutic applications, of a variety of Re-188-labeled agents is demonstrated. The high energy of the β-emission of Re-188 is particularly well suited for effective penetration in solid tumours. Its total radiation dose delivered to tissues is comparable to other radionuclides used in therapy. Furthermore, radiation safety and shielding requirements are an important subject of matter. In the case of bone metastases treatment, therapeutic ratios are presented in order to describe the efficacy of Re-188 usage.

Therapeutic efficacy of 188Re-MN-16ET lipiodol in an animal model of hepatocellular carcinoma

OBJECTIVE

In our recent study, we developed a new radiopharmaceutical (Re-188 MN-16ET lipiodol) with encouraging results for the treatment of liver malignancy. In this study, we further evaluated the therapeutic efficacy of this radiopharmaceutical by measuring tumor response and survival times in rats with liver tumors after intra-hepatic arterial injection of Re-188 MN-16ET lipiodol.

METHODS

Twelve male rats bearing hepatic tumors were divided into three groups. Group 1 received an intra-hepatic arterial injection of 18.5 MBq Re-188 MN-16ET lipiodol; Group 2 received lipiodol and Group 3 received normal saline. Tumor size was measured by liver sonography before injection, at 2, 4, and 8 weeks after injection. Survival time and response rate were calculated.

RESULTS

All rats showed good response and survived over 60 days in Group 1 while all rats showed poor response in Group 2 and Group 3 with only 25 % of rats in Group 2 and none (0 %) in Group 3 survived over 60 days. The p value was 0.0067 between Group 1 and Group 3; 0.04 between Group 1 and Group 2; and 0.034 between Group 2 and Group 3.

CONCLUSION

Re-188 MN-16ET lipiodol has good potential for the treatment of hepatoma.

Reduction of β-radiation exposure during preparation of 188Re-labelled Lipiodol for hepatocellular carcinoma treatment

Rhenium-188 (188Re) is of widespread interest for treating various diseases because of its attractive physical and chemical properties. The routine preparation of therapeutic doses of 188Re-labelled tracers can result in significant radiation exposure to the operator. We studied the impact of automating the preparation of 188Re-Lipiodol on the radiochemist's exposure, as well as the importance of the model of syringe shielding. To monitor radiation exposure continuously readable electronic personal dosimeters were used. Thermoluminescence dosimeters were fixed to the probable most exposed fingers of the radiochemist during preparation of the radiotracer and during the syringing. Dose rates were measured using a Babyline. Automation of the synthesis reduced personal dose equivalents from 2.60±4.35 to 1.61±1.20 µSv/GBq [Hp(10)] and from 38.37±55.28 to 21.84±16.14 µSv/GBq [Hp(0.07)]. Dose to the extremities was also reduced (-80% for the right hand; -58% for the left one). The Lemer-Pax PSWG syringe shield led to a slightly lower dose to the hands compared with the Medisystem (1.1±0.27 vs. 1.34±0.6 mSv/GBq for the right finger). Automation of the synthesis leads to a significant decrease in radiation exposure to the operator. The Lemer-Pax PSWG syringe shield provides better hand protection than the smaller Medisystem Mediclic.

(188)Re-SSS/Lipiodol: Development of a Potential Treatment for HCC from Bench to Bedside

Hepatocellular carcinoma (HCC) is the 5th most common tumour worldwide and has a dark prognosis. For nonoperable cases, metabolic radiotherapy with Lipiodol labelled with β-emitters is a promising therapeutic option. The Comprehensive Cancer Centre Eugène Marquis and the National Graduate School of Chemistry of Rennes (ENSCR) have jointly developed a stable and efficient labelling of Lipiodol with rhenium-188 (E_βmax = 2.1 MeV) for the treatment of HCC. The major “milestones” of this development, from the first syntheses to the recent first injection in man, are described.

Emergence and present status of Lu-177 in targeted radiotherapy: the Indian scenario

177Lu is presently considered to be a potential radionuclide for the development of agents for radionuclide therapy owing to its favorable nuclear decay characteristics [T 1/2 = 6.65 d, E β(max) = 0.497 MeV, E γ = 113 KeV (6.4%) and 208 KeV (11%)]. While the long half-life of this promising radioisotope offers distinct logistic advantage, particularly, in countries having limited reactor facilities, the feasibility of its large-scale production with adequate specific activity and excellent radionuclidic purity in medium flux research reactors constitute yet another desirable feature. Extensive studies have been carried out to optimize the production of this isotope, with high specific activity and radionuclidic purity by the (n,γ) route using the highest available flux and the optimum irradiation time. The gradual evolution of clin ical grade 177LuCl3 as a new radiochemical, ready for commercial deployment by Radiopharmaceuticals Division, Bhabha Atomic Research Centre, to nuclear medicine centers all over India was accomplished in 2010 in a stepwise manner with the commencement of the production of high specific activity 177Lu from enriched target in 2001. Research on 177Lu has demonstrated its immense potential in radiotherapeutic applications, a direct outcome of which has resulted in indigenous development of two agents viz. 177Lu-EDTMP and 177Lu-DOTA-TATE presently being evaluated in human patients for palliative care of bone pain due to skeletal metastases and treatment of malignancies of neuroendocrine origin, respectively. Using locally produced 177Lu, the radiolabeling of a plethora of other molecules with potential applicability in radiation synovectomy and targeted therapy of malignant tumors have been successfully demonstrated. A few of these agent such as a novel 177Lu-labeled porphyrin has shown considerable promise in initial studies and is presently evaluated. In the present article, our research efforts toward standardization of production methodology of 177Lu in high specific activity and its utilization in the devel opment of agents for targeted radiotherapy are being reported.

Automation of labelling of Lipiodol with high-activity generator-produced 188Re

This work describes optimisation of the kit formulation for labelling of Lipiodol with high-activity generator-produced rhenium-188. Radiochemical purity (RCP) was 92.52±2.3% and extraction yield was 98.56±1.2%. The synthesis has been automated with a TADDEO module (Comecer) giving a mean final yield of 52.68±9.6%, and reducing radiation burden to the radiochemist by 80%. Radiolabelled Lipiodol ((188)Re-SSS/Lipiodol) is stable for at least 7 days (RCP=91.07±0.9%).

Automated preparation of Re-188 lipiodol for the treatment of hepatocellular carcinoma

The iodinated oil lipiodol is commonly used as a carrier for in situ delivery of drugs or radioactivity to hepatic tumors. Recently, we reported a new kit formulation for high-activity labeling of lipiodol with the β-emitting radionuclide Re-188. Since the whole preparation involves different steps and complex manipulations of high-activity samples, we describe here an automated synthesis module that allows the easy preparation of sterile and pyrogen-free samples of Re-188 lipiodol ready to be administered to the patient. Important advantages include the possibility to incorporate high Re-188 activity into the lipiodol hydrophobic phase and a sharp reduction of radiation exposure of the operator assisting the labelling procedure. Application of this modular reaction system could be also extended to the preparation of other Re-188 radiopharmaceuticals and to compound labelled with different β-emitting therapeutic radionuclides.

Preparation of 177Lu-labeled oxine in lipiodol as a possible agent for therapy of hepatocellular carcinoma: a preliminary animal study

Hepatocellular carcinoma (HCC) is one of the most prevalent forms of cancer with high morbidity. (131)I-lipiodol is used clinically and has been found to be effective for the treatment of HCC. However, this preparation has its limitations, including compromised yield and stability of exchange labeling and unnecessary dose burden from gamma emissions. In the present study, (177)Lu-oxine in lipiodol was considered as a possible alternative for radioiodinated lipiodol. Oxine or 8-hydroxyquinoline was labeled with (177)Lu obtained by neutron irradiation of natural lutetium. Under optimized conditions, the radiolabeled complex was obtained with yields >98% and adequate in vitro stability. (177)Lu-oxine dispersed in lipiodol showed appreciable uptake into rat liver cells (normal and HCC-induced) in vitro. (177)Lu-oxine-lipiodol showed initial localization in the liver, but subsequent leakage of radioactivity with deposition in the skeletal tissue was seen. The studies suggest that (177)Lu-oxine dispersed in lipiodol might not be suitable for treatment of HCC.

Treatment of hepatocellular carcinoma with intra-arterial injection of radionuclides

Hepatocellular carcinoma (HCC) is becoming an important public health concern. Current therapeutic options are limited and new treatments are therefore being developed. The intra-arterial treatment chemoembolization has limited efficacy and few prospects for further progress. One particularly promising, though little used, alternative to chemoembolization is radioembolization with iodine-131 ((131)I) or rhenium-188 labeled lipiodol or yttrium-90 labeled microspheres (glass or resin beads). Three randomized studies have proven the effectiveness of (131)I-lipiodol in patients with HCC-as adjuvant therapy after surgery, compared with chemoembolization, and also in patients who have portal vein thrombosis. Microspheres enable the delivery of high-dose radiation (>200 Gy) to the tumor while sparing the neighboring hepatic tissue from overexposure. Overall, the efficacy of radioembolization has been good and toxic effects have been low. These results are comparable to those obtained with chemoembolization but further improvement can be expected by combining radioembolization with standard chemotherapy or with targeted therapies, such as anti-angiogenic drugs.

Biokinetic and dosimetric studies of 188Re-hyaluronic acid: a new radiopharmaceutical for treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and has very limited therapeutic options. Recently, it has been found that hyaluronic acid (HA) shows selective binding to CD44 receptors expressed in most cancer histotypes. Since the trend in cancer treatment is the use of targeted radionuclide therapy, the aim of this research was to label HA with rhenium-188 and to evaluate its potential use as a hepatocarcinoma therapeutic radiopharmaceutical.

METHODS

(188)Re-HA was prepared by a direct labelling method to produce a ReO(O-COO)(2)-type coordination complex. (188)Re-HA protein binding and its stability in saline, phosphate buffer, human serum and cysteine solutions were determined. Biokinetic and dosimetric data were estimated in healthy mice (n=60) using the Medical Internal Radiation Dose methodology and mouse model beta-absorbed fractions. To evaluate liver toxicity, alanine aminotranferase (AST) and aspartate aminotranferase (ALT) levels in mice were assessed and the liver maximum tolerated dose (MTD) of (188)Re-HA was determined.

RESULTS

A stable complex of (188)Re-HA was obtained with high radiochemical purity (>90%) and low serum protein binding (2%). Biokinetic studies showed a rapid blood clearance (T(1/2)alpha=21 min). Four hours after administration, (188)Re-HA was almost totally removed from the blood by the liver due to the selective uptake via HA-specific receptors (73.47+/-5.11% of the injected dose). The liver MTD in mice was approximately 40 Gy after 7.4 MBq of (188)Re-HA injection.

CONCLUSIONS

(188)Re-HA complex showed good stability, pharmacokinetic and dosimetric characteristics that confirm its potential as a new agent for HCC radiation therapy.

Effect of a 188Re-SSS lipiodol/131I-lipiodol mixture, 188Re-SSS lipiodol alone or 131I-lipiodol alone on the survival of rats with hepatocellular carcinoma

BACKGROUND AND AIM

It has been shown that the use of a cocktail of isotopes of different ranges of action leads to an increase in the effectiveness of metabolic radiotherapy. The purpose of the present study was to compare with a control group the effectiveness of three different treatments in rats bearing hepatocellular carcinoma (HCC), using (1) a mixture of lipiodol labelled with both I and Re, (2) lipiodol labelled with I alone and (3) lipiodol labelled with Re alone.

MATERIAL AND METHODS

Four groups were made up, each containing 14 rats with the N1-S1 tumour cell line. Group 1 received a mixture composed of 22 MBq of Re-SSS lipiodol and 7 MBq I-lipiodol. Group 2 received 14 MBq I-lipiodol. Group 3 received 44 MBq of Re-SSS lipiodol and group 4 acted as the control. The survival of the various groups was compared by a non-parametric test of log-rank, after a follow-up of 60, 180 and 273 days.

RESULTS

Compared with the controls, the rats treated with a mixture of Re-SSS lipiodol and I-lipiodol show an increase in survival, but only from day 60 onwards (P=0.05 at day 60 and 0.13 at days 180 and 273). For the rats treated with I-lipiodol, there was a highly significant increase in survival compared with the controls at day 60, day 180 and day 273 (P=0.03, 0.04 and 0.04, respectively). There is no significant increase in survival for the rats treated with Re-SSS lipiodol, irrespective of the follow-up duration (P=0.53 at day 60, 0.48 at day 180, and 0.59 at day 273).

CONCLUSIONS

In this study, I-lipiodol is the most effective treatment in HCC-bearing rats, because this is the only method that leads to a prolonged improvement of survival. These results cannot necessarily be extrapolated to humans because of the relatively small size and unifocal nature of the lesions in this study. It appears necessary to carry out a study in humans with larger tumours in order to compare these three treatments, particularly with a view to replacing I-labelled lipiodol by Re-labelled lipiodol. However, this study clearly demonstrated that, for small tumours, as in an adjuvant setting for example, I-labelled lipiodol should be a better option than Re-labelled lipiodol.

Association of cisplatin and intra-arterial injection of 131I-lipiodol in treatment of hepatocellular carcinoma: results of phase II trial

PURPOSE

Intra-arterial injections of 131I-lipiodol (131I-Lip) provide an effective treatment for hepatocellular carcinoma. In hepatocellular carcinoma cell cultures, concurrent administration of cisplatin increases the cytotoxicity of 131I. The efficacy and tolerance of intra-arterial injections of 131I-Lip combined with systemic cisplatin was tested in a phase II trial.

METHODS AND MATERIALS

The inclusion criteria were proven unresectable nonmetastatic hepatocellular carcinoma, compensated liver disease, and adequate laboratory test findings. Treatment comprised the combination of intra-arterial injection of 131I-Lip (2.2 GBq) with intravenous infusion of low-dose cisplatin. The combined treatment could be repeated.

RESULTS

A total of 41 patients were included; 37 had cirrhosis and 38 had measurable tumors. One to four treatments (median, two) were given. The cisplatin dose was 75 mg for the first course and 72 mg for the second. Grade 3-4 (n/n) adverse effects were observed in 14 patients, polymorphonuclear leukocytes (3/0), platelets (5/1), asthenia (1/0), pain (1/0), and vomiting (1/0). Four patients developed pulmonary toxicity; 2 cases were likely related to 131I-Lip administration and 1 was fatal. The response rate was 47% (18 of 38), and the 1- and 2-year survival rate was 73% +/- 7% and 48% +/- 9%, respectively.

CONCLUSION

This combination had a tolerable toxicity profile and provided an objective response rate, warranting a phase III trial.

Syntheses and reactivity of 'sulfur rich' Re(iii) and Tc(iii) complexes containing trithioperoxybenzoate, dithiobenzoate and dithiocarbamate ligands

Reduction-substitution reactions of [M(O)Cl(4)](-)(M=Re, (99)Tc) precursors with an excess of substituted dithiobenzoate ligands (R-PhCS(2))(-) in dichloromethane/methanol mixtures afford a series of six-coordinated neutral mixed-ligand complexes of the type M(III)(R-PhCS(3))(2)(R-PhCS(2))(M=Re; Rel--9; M=99)Tc; Tel--9). The coordination sphere is entirely filled by sulfur donor atoms, and the complexes adopt a distorted trigonal prismatic arrangement, as assessed by the X-ray crystal structure analysis of Re(4-Me-PhCS(3))(2)(4-Me-PhCS(2)), Re 2. These compounds show sharp proton and carbon NMR profiles, in agreement with the diamagnetism typical of low spin d(4) trigonal prismatic configurations. The red-ox processes involve reduction of the metal from Re(v) to Re(iii) and oxidation of dithiobenzoate to trithioperoxybenzoate. M2--9 complexes contain a substitution-inert [M(R-PhCS(3))(2)](+) moiety including the metal and two trithioperoxybenzoate fragments, while the third dithiobenzoate ligand is labile. The latter is efficiently replaced by reaction with better nucleophiles such as diethyldithiocarbamate giving a further class of mixed ligand complexes of the type M(III)(R-PhCS(3))(2)(Et(2)NCS(2))(M=Re; Re 10--18; M=(99)Tc; Tc--18), which retain the trigonal prismatic arrangement, as determined by the X-ray analyses of the representative compounds Re(PhCS(3))(2)(Et(2)NCS(2)), Re 10 and (99)Tc(PhCS(3))(2)(Et(2)NCS(2)), Tc 10.

Effect of Stabilized Iodized Oil Emulsion on Experimentally Induced Hepatocellular Carcinoma in Rats

PURPOSE

Previous studies have shown that the use of Lipiodol UltraFluid (LUF) emulsified with water leads to an increase in the tumoral uptake of iodine I 131-labeled LUF and reduced pulmonary uptake. Although emulsions containing LUF are currently used for chemoembolization of hepatocellular carcinomas (HCCs), this approach is impossible with intraarterial radiation therapy (RT) because of the problems of radiation protection linked to instability of the emulsions. The aims of this study were to develop stabilized emulsions of radiolabeled LUF of different particle sizes and viscosities and to study its biodistribution in rats with HCC.

MATERIALS AND METHODS

An emulsifier made of polyethylene glycol and hydrogenated castor oil was used to stabilize emulsions containing water and technetium Tc 99m-labeled Super Six Sulfur LUF. The various emulsions were injected in the hepatic arteries of rats with HCC. Twenty-four hours after injection, the rats were killed and the liver, tumor, and lungs were removed to perform ex-vivo gamma-counting to quantify tumoral, hepatic, and pulmonary uptake.

RESULTS

Emulsions of oil in water and water in oil of different viscosities (0.68-1.06 Pa.S) and particle size distributions (21-45 mum) were prepared and kept stable for more than 24 hours. Whatever the type of emulsion, the observed effect on tumoral uptake was the opposite of that expected. Indeed, a decrease in tumoral activity was observed (P < .05 in three of five cases) and a tendency toward increased pulmonary activity was observed (P < .05 in two of five cases) rather than any significant decrease.

CONCLUSIONS

This study made it possible to develop emulsions of radiolabeled iodized oil that remain stable for more than 24 hours. However, studies of biodistribution in rats with HCC failed to demonstrate any improvement in tumoral targeting, but rather showed a decrease in tumoral uptake that renders this approach impractical for intraarterial radiolabeled iodized oil RT as well as for intraarterial iodized oil chemoembolization. These results may possibly be explained by the use of an emulsifier containing lipophilic and hydrophilic components that modify the properties of LUF.