Timing of adjuvant radioimmunotherapy after cytoreductive surgery in experimental peritoneal carcinomatosis of colorectal origin

A study of peritoneal metastatic xenograft model of colorectal cancer in the treatment of hyperthermic intraperitoneal chemotherapy with Raltitrexed

Peritoneal metastasis of colorectal cancer is one of the most incident and fateful diseases among relapse cases. It shows a certain resistance to systemic chemotherapy. The perfusion system in clinic is complex and hard to be used in fundamental researches. This study aims at evaluating the effect of an improved hyperthermic intraperitoneal chemotherapy with Raltitrexed used in tumor-bearing mice with peritoneal metastatic colorectal carcinoma. The results showed that no severe adverse effect was observed. All control animals developed extensive peritoneal and mesenteric metastatic nodes. Tumor sites in the treatment groups were reduced significantly. The administration dose of Raltitrexed influenced concentration in systemic blood and peritoneal tissues. Temperature promoted the intracellular absorption of Raltitrexed significantly. Our findings reveal that hyperthermic intraperitoneal chemotherapy is an efficient therapy in treating peritoneal metastatic carcinoma in nude mice. It can effectively reduce the extension of carcinoma cells from macro and micro examination. The combination of hyperthermia and Raltitrexed resulted in an improved therapeutic effect on animal models.

Comparison between Three Promising ß-emitting Radionuclides, (67)Cu, (47)Sc and (161)Tb, with Emphasis on Doses Delivered to Minimal Residual Disease

PURPOSE: Radionuclide therapy is increasingly seen as a promising option to target minimal residual disease. Copper-67, scandium-47 and terbium-161 have a medium-energy β^- emission which is similar to that of lutetium-177, but offer the advantage of having diagnostic partner isotopes suitable for pretreatment imaging. The aim of this study was to compare the efficacy of ⁶⁷Cu, ⁴⁷Sc and ¹⁶¹Tb to irradiate small tumors.

METHODS: The absorbed dose deriving from a homogeneous distribution of ⁶⁷Cu, ⁴⁷Sc or ¹⁶¹Tb in water-density spheres was calculated with the Monte Carlo code CELLDOSE. The diameters of the spheres ranged from 5 mm to 10 µm, thus simulating micrometastases or single tumor cells. All electron emissions, including β^- spectra, Auger and conversion electrons were taken into account. Because these radionuclides differ in electron energy per decay, the simulations were run assuming that 1 MeV was released per µm³, which would result in a dose of 160 Gy if totally absorbed.

RESULTS: The absorbed dose was similar for the three radionuclides in the 5-mm sphere (146-149 Gy), but decreased differently in smaller spheres. In particular, ¹⁶¹Tb delivered higher doses compared to the other radionuclides. For instance, in the 100-µm sphere, the absorbed dose was 24.1 Gy with ⁶⁷Cu, 14.8 Gy with ⁴⁷Sc and 44.5 Gy with ¹⁶¹Tb. Auger and conversion electrons accounted for 71% of ¹⁶¹Tb dose. The largest dose differences were found in cell-sized spheres. In the 10-µm sphere, the dose delivered by ¹⁶¹Tb was 4.1 times higher than that from ⁶⁷Cu and 8.1 times that from ⁴⁷Sc.

CONCLUSION: ¹⁶¹Tb can effectively irradiate small tumors thanks to its decay spectrum that combines medium-energy β^- emission and low-energy conversion and Auger electrons. Therefore ¹⁶¹Tb might be a better candidate than ⁶⁷Cu and ⁴⁷Sc for treating minimal residual disease in a clinical setting.

Animal models of colorectal peritoneal metastasis

Colorectal cancer remains an important cause of mortality worldwide. The presence of peritoneal carcinomatosis (PC) causes significant symptoms and is notoriously difficult to treat. Therefore, informative preclinical research into the mechanisms and possible novel treatment options of colorectal PC is essential in order to improve the prognostic outlook in these patients. Several syngeneic and xenograft animal models of colorectal PC were established, studying a wide range of experimental procedures and substances. Regrettably, more sophisticated models such as those giving rise to spontaneous PC or involving genetically engineered mice are lacking. Here, we provide an overview of all reported colorectal PC animal models and briefly discuss their use, strengths, and limitations.

Dose Deposits from 90Y, 177Lu, 111In, and 161Tb in Micrometastases of Various Sizes: Implications for Radiopharmaceutical Therapy

Radiopharmaceutical therapy, traditionally limited to refractory metastatic cancer, is being increasingly used at earlier stages, such as for treating minimal residual disease. The aim of this study was to compare the effectiveness of (90)Y, (177)Lu, (111)In, and (161)Tb at irradiating micrometastases. (90)Y and (177)Lu are widely used β(-)-emitting radionuclides. (161)Tb is a medium-energy β(-) radionuclide that is similar to (177)Lu but emits a higher percentage of conversion and Auger electrons. (111)In emits γ-photons and conversion and Auger electrons.

METHODS

We used the Monte Carlo code CELLDOSE to assess electron doses from a uniform distribution of (90)Y, (177)Lu, (111)In, or (161)Tb in spheres with diameters ranging from 10 mm to 10 μm. Because these isotopes differ in electron energy per decay, the doses were compared assuming that 1 MeV was released per μm(3), which would result in 160 Gy if totally absorbed.

RESULTS

In a 10-mm sphere, the doses delivered by (90)Y, (177)Lu, (111)In, and (161)Tb were 96.5, 152, 153, and 152 Gy, respectively. The doses decreased along with the decrease in sphere size, and more abruptly so for (90)Y. In a 100-μm metastasis, the dose delivered by (90)Y was only 1.36 Gy, compared with 24.5 Gy for (177)Lu, 38.9 Gy for (111)In, and 44.5 Gy for (161)Tb. In cell-sized spheres, the dose delivered by (111)In and (161)Tb was higher than that of (177)Lu. For instance, in a 10-μm cell, (177)Lu delivered 3.92 Gy, compared with 22.8 Gy for (111)In and 14.1 Gy for (161)Tb.

CONCLUSION

(177)Lu, (111)In, and (161)Tb might be more appropriate than (90)Y for treating minimal residual disease. (161)Tb is a promising radionuclide because it combines the advantages of a medium-energy β(-) emission with those of Auger electrons and emits fewer photons than (111)In.

Therapeutic Efficacy of Alpha-RIT Using a (213)Bi-Anti-hCD138 Antibody in a Mouse Model of Ovarian Peritoneal Carcinomatosis

Purpose

Ovarian peritoneal carcinomatosis is a pathology for which effective cures are currently lacking. New research protocols seek to eradicate residual micrometastases following cytoreductive surgery by using hyperthermic intraperitoneal chemotherapy (HIPEC) or radioimmunotherapy (RIT). This study aims to first develop alpha-RIT using an anti-CD138 mAb radiolabeled with an alpha-emitter, bismuth-213 (²¹³Bi-B-B4) and HIPEC in a nude mouse model and second to compare and combine these techniques.

Material and methods

A murine model of postoperative ovarian peritoneal carcinomatosis was established. A pilot group of six mice received an intraperitoneal injection of luciferase-tagged SHIN-3 cells and bioluminescence was measured every day. Cytoreductive surgery was performed at day 14 (n = 4) and 29 (n = 2). Because the residual bioluminescence signal measured after surgery was equivalent to that obtained 3 days after the graft, HIPEC or alpha-RIT treatments were applied 3 days after the graft. Ten mice were treated by HIPEC with cisplatine (37.5 mg/mL), 11 with 7.4 MBq of ²¹³Bi-B-B4, seven with 11.1 MBq of ²¹³Bi-B-B4, and 10 mice were treated with the combined therapy (HIPEC + 7.4 MBq of ²¹³Bi-B-B4). Eleven mice received no treatment. Bioluminescence imaging and survival were assessed.

Results

Alpha-RIT 7.4 MBq and 11.1 MBq significantly improved survival (p = 0.0303 and p = 0.0070, respectively), whereas HIPEC and HIPEC + alpha-RIT treatments did not significantly ameliorate survival as compared to the control group.

Conclusion

Survival was significantly increased by alpha-RIT treatment in mice with peritoneal carcinomatosis of ovarian origin; however, HIPEC alone or in combination with alpha-RIT had no significant effect.

Emerging trends for radioimmunotherapy in solid tumors

Due to its ability to target both known and occult lesions, radioimmunotherapy (RIT) is an attractive therapeutic modality for solid tumors. Poor tumor uptake and undesirable pharmacokinetics, however, have precluded the administration of radioimmunoconjugates at therapeutically relevant doses thereby limiting the clinical utility of RIT. In solid tumors, efficacy of RIT is further compromised by heterogeneities in blood flow, tumor stroma, expression of target antigens and radioresistance. As a result significant efforts have been invested toward developing strategies to overcome these impediments. Further, there is an emerging interest in exploiting short-range, high energy α-particle emitting radionuclides for the eradication of minimal residual and micrometastatic disease. As a result several modalities for localized therapy and models of minimal disease have been developed for preclinical evaluation. This review provides a brief update on the recent efforts toward improving the efficacy of RIT for solid tumors, and development of RIT strategies for minimal disease associated with solid tumors. Further, some of promising approaches to improve tumor targeting, which showed promise in the past, but have now been ignored are also discussed.

Adjuvant radioimmunotherapy improves survival of rats after resection of colorectal liver metastases

OBJECTIVE

The aim of this study was to test the hypothesis that adjuvant radioimmunotherapy (RIT) prevents recurrent liver metastases and/or results in improved survival after tumorectomy in an experimental model.

BACKGROUND

Although partial hepatectomy can improve 5-year survival of patients with colorectal liver metastases up to 58%, recurrent tumor growth in the liver occurs frequently. Radioimmunotherapy using radiolabeled monoclonal antibodies directed against tumor-associated antigens is considered most suited for treating minimal residual disease and could therefore serve as an adjuvant after surgery.

METHODS

Liver metastases were induced in male Wag/Rij rats by a mini-laparotomy with intrahepatic injection of 0.3 × 106 CC531 tumor cells. The biodistribution of the radiolabeled monoclonal antibody MG1, directed against a 80-kDa cell surface antigen on CC531 tumors, in this model was determined at 1, 3, and 7 days after intravenous administration. The therapeutic efficacy of 177Lu-MG1 was compared with that of a sham antibody (UPC10), labeled with the same activity dose of Lu-177, and saline only. Radioimmunotherapy was administered either at the day of the tumorectomy (day 14 after tumor cell inoculation) or 7 days later. Primary endpoint was survival.

RESULTS

Radiolabeled MG1 preferentially accumulated in tumor lesions in the liver reaching a maximum 3 days postinjection (8.7 ± 0.6% injected dose per gram). Both the administration of 177Lu-MG1 and 177Lu-UPC10 resulted in a transient decrease in body weight. No other signs of clinical discomfort were registered. The survival curves of the group that received 177Lu-UPC10 and the group that received saline only did not differ (P=0.886). Administration of RIT immediately after surgery improved survival compared to administration of the control antibody (hazard ratio [HR], 1.54; P = 0.051), which was even more pronounced when survival was adjusted for the weight of the resected tumor (HR, 1.71; P = 0.027). A therapeutic efficacy of delayed treatment seemed likely (HR, 2.34; P = 0.055). Survival after early administration did not differ from delayed administration (HR, 1.16; P = 0.763).

CONCLUSION

This study provides proof of principle that RIT can be an effective adjuvant treatment modality after surgical treatment of colorectal liver metastases.

Cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy improves survival of gastric cancer with peritoneal carcinomatosis: evidence from an experimental study

Background

Cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC) has been considered as a promising treatment modality for gastric cancer with peritoneal carcinomatosis (PC). However, there have also been many debates regarding the efficacy and safety of this new approach. Results from experimental animal model study could help provide reliable information. This study was to investigate the safety and efficacy of CRS + HIPEC to treat gastric cancer with PC in a rabbit model.

Methods

VX2 tumor cells were injected into the gastric submucosa of 42 male New Zealand rabbits using a laparotomic implantation technique, to construct rabbit model of gastric cancer with PC. The rabbits were randomized into control group (n = 14), CRS alone group (n = 14) and CRS + HIPEC group (n = 14). The control group was observed for natural course of disease progression. Treatments were started on day 9 after tumor cells inoculation, including maximal removal of tumor nodules in CRS alone group, and maximal CRS plus heperthermic intraperitoneal chemoperfusion with docetaxel (10 mg/rabbit) and carboplatin (40 mg/rabbit) at 42.0 ± 0.5°C for 30 min in CRS + HIPEC group. The primary endpoint was overall survival (OS). The secondary endpoints were body weight, biochemistry, major organ functions and serious adverse events (SAE).

Results

Rabbit model of gastric cancer with PC was successfully established in all animals. The clinicopathological features of the model were similar to human gastric PC. The median OS was 24.0 d (95% confidence interval 21.8 - 26.2 d ) in the control group, 25.0 d (95% CI 21.3 - 28.7 d ) in CRS group, and 40.0 d (95% CI 34.6 - 45.4 d ) in CRS + HIPEC group (P = 0.00, log rank test). Compared with CRS only or control group, CRS + HIPEC could extend the OS by at least 15 d (60%). At the baseline, on the day of surgery and on day 8 after surgery, the peripheral blood cells counts, liver and kidney functions, and biochemistry parameters were all comparable. SAE occurred in 0 animal in control group, 2 animals in CRS alone group including 1 animal death due to anesthesia overdose and another death due to postoperative hemorrhage, and 3 animals in CRS + HIPEC group including 1 animal death due to anesthesia overdose, and 2 animal deaths due to diarrhea 23 and 27 d after operation.

Conclusions

In this rabbit model of gastric cancer with PC, CRS alone could not bring benefit while CRS + HIPEC with docetaxel and carboplatin could significantly prolong the survival with acceptable safety.

177Lu-immunotherapy of experimental peritoneal carcinomatosis shows comparable effectiveness to 213Bi-immunotherapy, but causes toxicity not observed with 213Bi

PURPOSE

(213)Bi-d9MAb-immunoconjugates targeting gastric cancer cells have effectively cured peritoneal carcinomatosis in a nude mouse model following intraperitoneal injection. Because the β-emitter (177)Lu has proven to be beneficial in targeted therapy, (177)Lu-d9MAb was investigated in this study in order to compare its therapeutic efficacy and toxicity with those of (213)Bi-d9MAb.

METHODS

Nude mice were inoculated intraperitoneally with HSC45-M2 gastric cancer cells expressing d9-E-cadherin and were treated intraperitoneally 1 or 8 days later with different activities of specific (177)Lu-d9MAb immunoconjugates targeting d9-E-cadherin or with nonspecific (177)Lu-d8MAb. Therapeutic efficacy was evaluated by monitoring survival for up to 250 days. For evaluation of toxicity, both biodistribution of (177)Lu-d9MAb and blood cell counts were determined at different time points and organs were examined histopathologically.

RESULTS

Treatment with (177)Lu-immunoconjugates (1.85, 7.4, 14.8 MBq) significantly prolonged survival. As expected, treatment on day 1 after tumour cell inoculation was more effective than treatment on day 8, and specific (177)Lu-d9MAb conjugates were superior to nonspecific (177)Lu-d8MAb. Treatment with 7.4 MBq of (177)Lu-d9MAb was most successful, with 90% of the animals surviving longer than 250 days. However, treatment with therapeutically effective activities of (177)Lu-d9MAb was not free of toxic side effects. In some animals lymphoblastic lymphoma, proliferative glomerulonephritis and hepatocarcinoma were seen but were not observed after treatment with (213)Bi-d9MAb at comparable therapeutic efficacy.

CONCLUSION

The therapeutic efficacy of (177)Lu-d9MAb conjugates in peritoneal carcinomatosis is impaired by toxic side effects. Because previous therapy with (213)Bi-d9MAb revealed comparable therapeutic efficacy without toxicity it should be preferred for the treatment of peritoneal carcinomatosis.

Intraoperative hyperthermic intraperitoneal chemotherapy after cytoreductive surgery for peritoneal carcinomatosis in an experimental model

BACKGROUND

The combination of cytoreductive surgery (CS) and hyperthermic intraperitoneal chemotherapy (HIPEC) is the treatment of choice for selected patients with peritoneal carcinomatosis (PC) of colorectal origin. However, it remains to be proven whether the addition of HIPEC to CS is essential for the reported survival benefit.

METHODS

Sixty WAG/Rij rats were inoculated intraperitoneally with the rat colonic carcinoma cell line CC-531. Animals were randomized into three treatment groups: CS alone, CS followed by HIPEC (mitomycin 15 mg/m(2) ) and CS followed by HIPEC (mitomycin 35 mg/m(2) ). Survival was the primary outcome parameter.

RESULTS

The median survival of rats treated with CS alone was 43 days. Rats receiving HIPEC 15 mg/m(2) and HIPEC 35 mg/m(2) both had a significantly longer median survival of 75 days (P = 0·003) and 97 days (P < 0·001) respectively. Rats receiving HIPEC showed a significantly lower tumour load at autopsy compared with rats treated with CS alone.

CONCLUSION

A combination of CS and HIPEC results in longer survival than CS alone in rats with PC of colorectal origin.

Can antibody galactosylation be used to improve radioimmunotherapy of induced peritoneal carcinomatosis of colonic origin in the rat?

In radioimmunotherapy (RIT), hematologic toxicity is the dose-limiting toxicity due to the long circulatory half-life of the antibody. Although intraperitoneal (i.p.) RIT results in high uptake of i.p. growing tumors, the radiolabeled antibody enters the circulation, resulting in bone marrow toxicity. Carbohydrate modification of antibodies could induce accelerated clearance of the antibody via the hepatic asialoglycoprotein receptor, thereby reducing exposure to normal tissues. In this study, we investigated whether galactosylation of an antibody in a model of peritoneal carcinomatosis (PC) of colonic origin could be used to improve targeting of i.p. growing tumors. Therefore, the biodistribution of the galactosylated and nongalactosylated anti-CC531 antibody, MG1, after i.p. injection was determined in a model of peritoneal carcinomatosis of CC-531 colon tumors in Wag/Rij rats. Uptake of the radiolabeled antibodies in the tumor and relevant organs was determined at 2, 4, 24, and 48 hours after injection. Galactosylation of the antibody did not affect the binding affinity of MG1. Remarkably, the uptake of Gal-MG1 in tumors was higher than that of MG1 at 2 and 4 hours after injection. After 24 and 48 hours, uptake of Gal-MG1 in tumor tissue was lower than that of MG1. Gal-MG1 cleared from the blood within hours after administration. At 2-24 hours after administration, tumor-to-blood ratios obtained with Gal-MG1 were significantly higher than those obtained with unmodified MG1. Antibody galactosylation resulted in improved tumor-non-tumor ratios after i.p. injection in a model of PC. This could improve the efficiency of RIT, especially in combination with short-lived nonresidualizing radionuclides.

Radioimmunotherapy improves survival of rats with microscopic liver metastases of colorectal origin

Background

Half of the patients with colorectal cancer develop liver metastases during the course of their disease. The aim of the present study was to assess the efficacy of radioimmunotherapy (RIT) with a radiolabeled monoclonal antibody (mAb) to treat experimental colorectal liver metastases.

Methods

Male Wag/Rij rats underwent a minilaparotomy with intraportal injection of 1 × 10⁶ CC531 tumor cells. The biodistribution of ¹¹¹In-labeled MG1, 1 day after intravenous administration, was determined in vivo and compared with that of an isotype-matched control antibody (UPC-10). The maximal tolerated dose (MTD) of ¹⁷⁷Lu-labeled MG1 was determined and the therapeutic efficacy of ¹⁷⁷Lu-MG1 at MTD was compared with that of ¹⁷⁷Lu-UPC-10 and saline only. RIT was administered either at the day of tumor inoculation or 14 days after tumor inoculation. Primary endpoint was survival.

Results

¹¹¹In-MG1 preferentially accumulated in CC531 liver tumors (9.2 ± 3.7%ID/g), whereas ¹¹¹In-UPC-10 did not (0.8 ± 0.1%ID/g). The MTD of ¹⁷⁷Lu-MG1 was 400 MBq/kg body weight. Both the administration of ¹⁷⁷Lu-MG1 and ¹⁷⁷Lu-UPC-10 had no side-effects except a transient decrease in body weight. The survival curves of the group that received ¹⁷⁷Lu-UPC-10 and the group that received saline only did not differ (P = 0.407). Administration of ¹⁷⁷Lu-MG1 RIT immediately after surgery improved survival significantly compared with administration of ¹⁷⁷Lu-UPC-10 (P = 0.009) whereas delayed treatment did not (P = 0.940).

Conclusion

This study provides proof of principle that RIT can be an effective treatment modality for microscopic liver metastases, whereas RIT is not effective in larger tumors.

Microdistribution of targeted, fluorescently labeled anti-carcinoembryonic antigen antibody in metastatic colorectal cancer: implications for radioimmunotherapy

PURPOSE

Most radioimmunotherapy studies on radiolabeled antibody distribution are based on autoradiographic and radioluminographic data, which provide a lack of detailed information due to low resolution. We used fluorescently labeled anti-carcinoembryonic antigen (CEA) antibody (A5B7) to investigate quantitatively the kinetics and microdistribution of antibody in a clinically relevant orthotopic colorectal cancer model (LS174T) using high-resolution digital microscopy.

EXPERIMENTAL DESIGN

Nude mice bearing LS174T liver orthotopic tumors received a single i.v. injection of fluorescently labeled A5B7 and were sacrificed at 10 minutes, 1 hour, or 24 hours postinjection. Before sacrifice, mice were injected with the perfusion marker Hoechst 33342. An anti-CD31 antibody was used to detect blood vessel distribution. Cryostat sections were processed with immunofluorescence procedures and analyzed with fluorescence microscopy and image analysis techniques. The fluorescence images were related to morphologic images of the same or adjacent tumor sections.

RESULTS

Fluorescently labeled antibody showed rapid, selective uptake into tumor deposits, with a strong negative correlation with tumor size at 10 minutes and 1 hour (P < or = 0.01). By 24 hours, the correlation was no longer significant. The study showed movement of antibody across the tumor with time and a tendency to localize more uniformly by later time points (24 hours). The rate of antibody motility was similar in small and large tumor metastases, but small deposits showed more rapid antibody localization. Intratumoral vessels were positively related to tumor size (P < or = 0.001).

CONCLUSION

The obtained data suggest that radioimmunotherapy can be highly efficient in an adjuvant or minimal residual disease setting.

Use of antibodies and immunoconjugates for the therapy of more accessible cancers

There are currently 6 unconjugated antibodies and 3 immunoconjugates approved for use in the United States in a variety of cancers, with a considerable number of new agents in clinical testing and preclinical development. Unconjugated antibodies alone can be effective, but more often, antibodies need to be combined with chemotherapy, which enhances the efficacy of the standard treatment. Immunoconjugates tend to be more effective than their unconjugated counterparts, but their increased toxicity often restricts when and how they are used. In order to improve efficacy, a number of immunoconjugates are being examined in settings where the disease is more easily accessible, such as leukemias, or within compartments that allow easier and more direct access to the tumor, such as in the peritoneal cavity or brain, or both locally and systemically, in adjuvant situations, where the disease burden has been reduced by some other means, and with the main goal of these treatments being to kill residual disease.

A comparison between radioimmunotherapy and hyperthermic intraperitoneal chemotherapy for the treatment of peritoneal carcinomatosis of colonic origin in rats

BACKGROUND

Cytoreductive surgery (CS) followed by heated intraperitoneal chemotherapy (HIPEC) is considered the standard of care for the treatment of patients with peritoneal carcinomatosis (PC) of colorectal cancer (CRC). These surgical procedures result in a median survival of 2 years at the cost of considerable morbidity and mortality. In preclinical studies, radioimmunotherapy (RIT) improved survival after CS in a model of induced PC of colonic origin. In the present studies we aimed to compare the efficacy and toxicity of CS followed by adjuvant RIT in experimental PC to the standard of care, HIPEC.

METHODS

PC was induced by intraperitoneal inoculation of CC-531 colon carcinoma cells in three groups of Wag/Rij rats. Treatment comprised CS only, CS + RIT or CS + HIPEC, immediately after surgery. RIT consisted of intraperitoneal administration of 74 MBq Lutetium-177 labeled MG1. HIPEC was performed by a closed abdomen perfusion technique using mitomycin C (16 mg/L during 60 minutes). The primary endpoint was survival.

RESULTS

CS only or combined with RIT was well tolerated. Rats receiving CS + HIPEC were lethargic, suffered from diarrhea, and lost significantly more weight in the first postoperative week. Median survival of rats treated with CS + RIT was significantly longer than after CS alone (97 and 57 days, respectively, P < .004), whereas survival after CS + HIPEC or CS alone were not significantly different (76 and 57 days, respectively, P = .17).

CONCLUSION

Survival after CS was significantly improved by RIT with Lutetium-177-MG1 in rats with PC of colorectal origin. Adjuvant HIPEC did not improve survival and was more toxic than adjuvant RIT.