Proposed Risk Stratification and Patterns of Radioactive Iodine Therapy in Malignant Struma Ovarii.

Introduction: Malignant struma ovarii (MSO) is a rare thyroid cancer arising within an ovarian teratoma. While surgical excision of the primary tumor is widely accepted as standard of care, recommendations for adjuvant treatment of MSO-whether or not to administer radioactive iodine (RAI)-are based largely on case reports and remain debated. In this study, we aimed to propose a risk stratification and analyze RAI utilization patterns in MSO cases. Methods: The National Cancer Database (NCDB) was queried for patients with MSO between 2004 and 2016. Demographic, oncological, and clinicopathologic data were compared between groups using Fisher's exact test. Kaplan-Meier curves were used to estimate overall survival (OS), and variables associated with OS were assessed via univariate Cox regression. We adapted the 2015 American Thyroid Association risk guidelines for MSO patients. We stratified patients into low-, intermediate-, and high-risk groups using metastasis, extraovarian extension, lymphovascular invasion, lymph node status, surgical margins, tumor size, and grade. Risk stratification, demographic, oncological, and clinicopathologic data were compared between the groups receiving and not receiving RAI therapy. We then queried the Surveillance, Epidemiology, and End Results (SEER) 18 registry for patients with MSO between 2000 and 2018 to confirm our risk stratification analysis. Results: In the NCDB analysis, a total of 158 patients were identified, and 19 received RAI. RAI therapy was associated with distant metastasis (p = 0.005) and lymph node status (p = 0.012). Twenty-one NCDB patients were stratified as high risk, and 30% of high-risk patients received RAI. High-risk stratification was associated with decreased OS via univariate Cox regression (hazard ratio = 4.0 [95% confidence interval 1.11-14.26], p = 0.034). In our subsequent analysis using the SEER registry, there were 95 MSO patients, and 18 received RAI. Again, the majority of high-risk patients did not receive RAI, with only 41% of high-risk patients receiving RAI. Conclusions: MSO is a rare malignancy with apparently variable and inconsistent patterns of postoperative RAI administration. The risk stratification described here provides a framework to identify patients potentially at risk for mortality, and utilization of RAI in this group should be studied further.

Moderate Static Magnet Fields Suppress Ovarian Cancer Metastasis via ROS-Mediated Oxidative Stress.

Metastasis is the leading cause of cancer patient death, which is closely correlated with reactive oxygen species (ROS) levels. It is well known that the effects of ROS on tumors are diverse, depending on ROS concentration and cell type. We found that ovarian cancer cells have significantly lower levels of ROS than normal ovarian cells. Moreover, increased ROS levels in ovarian cancer cells can substantially inhibit their migration and invasion ability. Furthermore, the results show that moderate static magnetic field (SMF) can inhibit ovarian cancer cell migration, invasion, and stemness in a ROS-dependent manner. RNA sequencing results confirm that SMFs increased the oxidative stress level and reduced the stemness of ovarian cancer cells. Consistently, the expressions of stemness-related genes were significantly decreased, including hyaluronan receptor (CD44), SRY-box transcription factor 2 (Sox2), and cell myc proto-oncogene protein (C-myc). Furthermore, moderate SMFs provided by a superconducting magnet and permanent magnet have good biosafety and can both inhibit ovarian cancer metastasis in mice. Therefore, our study demonstrates the effects of SMFs on oxidative stress and metastasis in the ovarian cancer cells, which reveals the potential of applying SMF as a physical method in cancer therapy in the future.

Molecular imaging-monitored radiofrequency hyperthermia-enhanced intratumoral herpes simplex virus-thymidine kinase gene therapy for rat orthotopic ovarian cancer.

Objective: To establish the technique of intratumoral combination therapy of radiofrequency hyperthermia (RFH) with herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy for rat ovarian cancers.Material and methods: This study consisted of three parts: (1) in vitro experiments to establish the 'proof of principal' that combination of RFH and HSV-TK gene therapy has the synergistic effect on human ovarian cancer cells; (2) creation of bioluminescence imaging-detectable rat ovarian cancer model; and (3) in vivo experiments using this rat model to validate the technical feasibility of the combination therapy. Cells and nude rats were divided into four groups: (i) combination therapy (HSV-TK/GCV + RFH); (ii) RFH; (iii) HSV-TK/GCV; and (iv) phosphate-buffered saline (PBS). Data were analyzed using Dunnett t-test or Kruskal-Wallis test.Results: Cell proliferation assay demonstrated significantly greater reduction in viable cells with the combination therapy [0.52 (0.43, 0.61)] compared to other treatments [RFH 0.90 (0.84, 0.96), HSV-TK/GCV 0.71 (0.53, 0.88), PBS 1 (1, 1); p < .05]. For 24 rat models with bioluminescence imaging-detectable orthotopic ovarian cancer (n = 6 per group), optical imaging demonstrated significantly decreased relative bioluminescence signal with the combination therapy [0.81 (0.52, 1.08)] compared to other treatments [RFH 3.60 (2.34, 4.86), HSV-TK/GCV 2.21 (1.71, 2.71), PBS 3.74 (3.19, 4.29); p < .001]. Ultrasound imaging demonstrated the smallest relative tumor volume with the combination therapy [0.78 (0.45, 1.11) versus 3.50 (2.67, 4.33), 2.10 (0.83, 3.37), 3.70 (1.79, 5.61); p < .05].Conclusion: The feasibility of intratumoral RFH-enhanced HSV-TK/GCV gene therapy was established on a unique rat model with molecular imaging-detectable orthotopic ovarian cancer.

Radiolabeled Antibodies Against Müllerian-Inhibiting Substance Receptor, Type II: New Tools for a Theranostic Approach in Ovarian Cancer.

We have developed the 16F12 mouse monoclonal antibody (mAb), which targets the Müllerian-inhibiting substance receptor, type II (MISRII), expressed by ovarian tumors. Here, we assessed in preclinical models the possibility of using radiolabeled 16F12 in a theranostic approach for small-volume ovarian peritoneal carcinomatosis, such as after cytoreductive surgery. Methods: DOTA-, DTPA- or deferoxamine mesylate-conjugated 16F12 mAb was radiolabeled with ß-particle (177Lu) or α-particle (213Bi) emitters for therapeutic use and with 89Zr for PET imaging. On the 13th postxenograft day, mice bearing intraperitoneal MISRII-positive AN3CA endometrial carcinoma cell xenografts were treated by conventional intraperitoneal radioimmunotherapy (IP-RIT) with 10 MBq of 177Lu-16F12 or 12.9 MBq of 213Bi-16F12 or by brief intraperitoneal radioimmunotherapy (BIP-RIT) using 50 MBq of 177Lu-16F12 or 37 MBq of 213Bi-16F12. For BIP-RIT, 30 min after injection of the radiolabeled mAbs, the peritoneal cavity was washed to remove the unbound radioactivity. The biodistribution of 177Lu- and 213Bi-16F12 mAbs was determined and then used for dose assessment. Hematologic toxicity was also monitored. Results: The 16F12 mAb was satisfactorily radiolabeled for both therapy and imaging. IP-RIT with 177Lu-16F12 was slightly more efficient in delaying tumor growth than IP-RIT with 213Bi-16F12. Conversely, 213Bi-16F12 was more efficient than 177Lu-16F12 in BIP-RIT. The biodistribution analysis showed that the tumor-to-blood uptake ratio was significantly higher with BIP-RIT than with IP-RIT for both 213Bi- and 177Lu-16F12. Hematologic toxicity was more pronounced with 177Lu-16F12 than with 213Bi-16F12. SPECT/CT images (after BIP-RIT with 177Lu-16F12) and PET/CT images (after injection of 89Zr-16F12 in the tail vein) showed focal uptake at the tumor site. Conclusion: Radiolabeled 16F12 could represent a new theranostic tool for small-volume ovarian peritoneal carcinomatosis. Specifically, 213Bi-16F12-based BIP-RIT could be proposed to selected patients as an alternative adjuvant treatment immediately after cytoreductive surgery. An anti-MISRII mAb is currently being used in a first-in-human study, thus making radiolabeled anti-MISRII mAbs a realistic theranostic option for the clinic.

Theranostic Nanoparticles Loaded with Imaging Probes and Rubrocurcumin for Combined Cancer Therapy by Folate Receptor Targeting.

The combination of different therapeutic modalities is a promising option to combat the recurrence of tumors. In this study, polylactic and polyglycolic acid nanoparticles were used for the simultaneous delivery of a boron-curcumin complex (RbCur) and an amphiphilic gadolinium complex into tumor cells with the aim of performing boron and gadolinium neutron capture therapy (NCT) in conjunction with the additional antiproliferative effects of curcumin. Furthermore, the use of Gd complexes allows magnetic resonance imaging (MRI) assessment of the amount of B and Gd internalized by tumor cells. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles were targeted to ovarian cancer (IGROV-1) cells through folate receptors, by including in the formulation a PEGylated phospholipid functionalized with the folate moiety. NCT was performed on IGROV-1 cells internalizing 6.4 and 78.6 µg g-1 of 10 B and 157 Gd, respectively. The synergic action of neutron treatment and curcumin cytotoxicity was shown to result in a significant therapeutic improvement.

Absorbed Doses and Risk Estimates of (211)At-MX35 F(ab')2 in Intraperitoneal Therapy of Ovarian Cancer Patients.

PURPOSE: Ovarian cancer is often diagnosed at an advanced stage with dissemination in the peritoneal cavity. Most patients achieve clinical remission after surgery and chemotherapy, but approximately 70% eventually experience recurrence, usually in the peritoneal cavity. To prevent recurrence, intraperitoneal (i.p.) targeted α therapy has been proposed as an adjuvant treatment for minimal residual disease after successful primary treatment. In the present study, we calculated absorbed and relative biological effect (RBE)-weighted (equivalent) doses in relevant normal tissues and estimated the effective dose associated with i.p. administration of (211)At-MX35 F(ab')2. METHODS AND MATERIALS: Patients in clinical remission after salvage chemotherapy for peritoneal recurrence of ovarian cancer underwent i.p. infusion of (211)At-MX35 F(ab')2. Potassium perchlorate was given to block unwanted accumulation of (211)At in thyroid and other NIS-containing tissues. Mean absorbed doses to normal tissues were calculated from clinical data, including blood and i.p. fluid samples, urine, γ-camera images, and single-photon emission computed tomography/computed tomography images. Extrapolation of preclinical biodistribution data combined with clinical blood activity data allowed us to estimate absorbed doses in additional tissues. The equivalent dose was calculated using an RBE of 5 and the effective dose using the recommended weight factor of 20. All doses were normalized to the initial activity concentration of the infused therapy solution. RESULTS: The urinary bladder, thyroid, and kidneys (1.9, 1.8, and 1.7 mGy per MBq/L) received the 3 highest estimated absorbed doses. When the tissue-weighting factors were applied, the largest contributors to the effective dose were the lungs, stomach, and urinary bladder. Using 100 MBq/L, organ equivalent doses were less than 10% of the estimated tolerance dose. CONCLUSION: Intraperitoneal (211)At-MX35 F(ab')2 treatment is potentially a well-tolerated therapy for locally confined microscopic ovarian cancer. Absorbed doses to normal organs are low, but because the effective dose potentially corresponds to a risk of treatment-induced carcinogenesis, optimization may still be valuable.

Study of the therapeutic effect of 188Re labeled folate targeting albumin nanoparticle coupled with cis-diamminedichloroplatinum cisplatin on human ovarian cancer.

This paper aimed to investigate the treatment efficiency of 188Re labeled folate targeting albumin nanoparticles with cis-Diamminedichloroplatinum Cisplatin (188Re-folate-CDDP/HAS MNP) on human ovarian cancer. SKOV3 cells or tumor-bearing mice were divided into different groups and treated as follow: (A) negative control; (B) chemotherapy; (C) radiotherapy; (D) hyperthermia; (E) chemotherapy and radiotherapy; (F) chemotherapy and hyperthermia; (G) radiotherapy and hyperthermia; (H) chemotherapy, radiotherapy and hyperthermia. Treatment of B to H inhibited proliferation of SKOV3 cells, with the greatest inhibition being observed in group H (P<0.05). Obvious apoptotic hypodiploid peak appeared beside G1 phase in groups of B to H. The apoptotic rates of SKOV3 cells in groups of A to H were 0.08%, 7.56%, 8.64%, 17.14%, 21.64%, 23.77%, 33.94% and 57.16%, respectively. Our findings in vivo study showed that the mass of tumor in each group of B to H was significantly lower than that in the negative control (p <0.05). In addition, compared with each group of B to G, group H showed highest inhibition of tumor growth (p<0.05). In conclusion, the combination of magnetic induced hyperthermia, chemotherapy and targeted radionuclide of radiation exposure can effectively inhibit the growth of ovarian cancer, which indicates a potential applications in ovarian cancer treatment.

Radiation therapy is a treatment to be considered for recurrent epithelial ovarian cancer after chemotherapy.

AIMS AND BACKGROUND: Radiation therapy provides a safe and effective alternative treatment option for recurrent epithelial ovarian cancer, although it has not been a treatment of choice. We evaluated the efficacy and toxicity of radiation therapy for recurrent epithelial ovarian cancer after chemotherapy according to the disease status. METHODS: This was a retrospective study of 38 patients with recurrent epithelial ovarian cancer treated with radiation therapy at the Asan Medical Center, Seoul, Korea, between January 1997 and December 2007. We analyzed their clinical characteristics and the outcome of radiation therapy. RESULTS: Thirty-eight patients were treated with radiation therapy. Their median age was 51.5 years. Most patients were FIGO stage III (27/38) with serous adenocarcinoma (26/38). All patients had received at least one regimen of platinum-based chemotherapy; 24 patients were sensitive to the first chemotherapy and the others were resistant. Lymph node and abdominopelvic wall were the most common sites of radiation therapy. The response rate was 65.0% (16 complete remissions and 10 partial remissions), and the median regression rate was 78.8% (range, -66.6 to 100.0). Median progression-free survival was 7.2 months (range, 1.0-66.6). In 28 patients who had a solitary relapsed site from the radiographic finding at the time of radiation therapy, it was 10.7 months (range, 1.8-66.6). Neither hematologic nor intestinal toxicity of grade 3-4 was observed. Prognostic factors were sensitivity to platinum and the site treated with radiation therapy. CONCLUSIONS: Radiation therapy is a treatment that should be considered for recurrent epithelial ovarian cancer, especially in good responders to platinum or patients with solitary relapsed lesions.

ACR-ASTRO practice guideline for the performance of therapy with unsealed radiopharmaceutical sources.

This guideline is intended to guide appropriately trained and licensed physicians performing therapy with unsealed radiopharmaceutical sources. Adherence to this guideline should help to maximize the efficacious use of these procedures, maintain safe conditions, and ensure compliance with applicable regulations. The topics dealt with in this guideline include indications for the use of iodine-131, both for the treatment of hyperthyroidism and thyroid carcinoma. In addition, indications for other less common procedures include those for the use of phosphorous-32 in its liquid and colloidal forms, strontium-89, samarium-153, and the use of Y-90 antibodies.

Small cell carcinoma of the ovary of the hypercalcaemic type: an analysis of clinical and prognostic aspects of a rare disease on the basis of cases published in the literature.

PURPOSE: Ovarian small cell carcinoma of the hypercalcaemic type is a very rare and highly aggressive malignant disease, mainly affecting young women. Due to the rarity of this tumour entity, prospective randomised trials are unlikely to be conducted, and the only retrospective analysis based on a large case series is from 1994. Since diagnostic and treatment modalities may have changed, we initiated this analysis. METHODS: The aim of our study was to review and analyse cases published since 1975 to validate former findings and to gather more information about therapy options, diagnostic and prognostic factors. A systematic literature search of the PubMed/Medline database was performed assessing all articles until September 2010. All retrieved articles were evaluated and cross-checked for references on the topic. In total, 135 cases were included, selected from 62 case reports and smaller case studies. RESULTS: Small cell carcinoma mostly affects women with a mean age of 23.4 years. They present with unspecific symptoms like abdominal pain or palpable mass, sometimes accompanied by an elevated calcium or CA-125 serum concentration. The tumour appears nearly almost unilaterally, mostly affecting the right ovary. Tumour stage is a clearly prognostic factor. Adjuvant chemotherapy consisting of etoposide, cisplatinum/carboplatinum or vinca alkaloids has shown improved survival, whereas radiotherapy has not. CONCLUSIONS: In spite of limitations this analysis provides new insights especially with respect to therapeutic aspects. This review underlines the importance of case reports in rare tumour entities in order to answer open questions.

Internet-based survey evaluating use of pain medications and attitudes of radiation oncology patients toward pain intervention.

PURPOSE: Pain is a common symptom among cancer patients, yet many patients do not receive adequate pain management. Few data exist quantifying analgesic use by radiation oncology patients. This study evaluated the causes of pain in cancer patients and investigated the reasons patients fail to receive optimal analgesic therapy. METHODS AND MATERIALS: An institutional review board-approved, Internet-based questionnaire assessing analgesic use and pain control was posted on the OncoLink (available at www.oncolink.org) Website. Between November 2005 and April 2006, 243 patients responded. They were predominantly women (73%), white (71%), and educated beyond high school (67%) and had breast (38%), lung (6%), or ovarian (6%) cancer. This analysis evaluated the 106 patients (44%) who underwent radiotherapy. RESULTS: Of the 106 patients, 58% reported pain from their cancer treatment, and 46% reported pain directly from their cancer. The pain was chronic in 51% and intermittent in 33%. Most (80%) did not use medication to manage their pain. Analgesic use was significantly less in patients with greater education levels (11% vs. 36%, p = 0.002), with a trend toward lower use by whites (16% vs. 32%, p = 0.082) and women (17% vs. 29%, p = 0.178). The reasons for not taking analgesics included healthcare provider not recommending medication (87%), fear of addiction or dependence (79%), and inability to pay (79%). Participants experiencing pain, but not taking analgesics, pursued alternative therapies for relief. CONCLUSIONS: Many radiation oncology patients experience pain from their disease and cancer treatment. Most study participants did not use analgesics because of concerns of addiction, cost, or failure of the radiation oncologist to recommend medication. Healthcare providers should have open discussions with their patients regarding pain symptoms and treatment.

Targeted therapy in nuclear medicine--current status and future prospects.

In recent years, a number of new developments in targeted therapies using radiolabeled compounds have emerged. New developments and insights in radioiodine treatment of thyroid cancer, treatment of lymphoma and solid tumors with radiolabeled monoclonal antibodies (mAbs), the developments in the application of radiolabeled small receptor-specific molecules such as meta-iodobenzylguanidine and peptides and the position of locoregional treatment in malignant involvement of the liver are reviewed. The introduction of recombinant human thyroid-stimulating hormone and the possibility to enhance iodine uptake with retinoids has changed the radioiodine treatment protocol of patients with thyroid cancer. Introduction of radiolabeled mAbs has provided additional treatment options in patients with malignant lymphoma, while a similar approach proves to be cumbersome in patients with solid tumors. With radiolabeled small molecules that target specific receptors on tumor cells, high radiation doses can be directed to tumors in patients with disseminated disease. Radiolabeled somatostatin derivatives for the treatment of neuroendocrine tumors are the role model for this approach. Locoregional treatment with radiopharmaceuticals of patients with hepatocellular carcinoma or metastases to the liver may be used in inoperable cases, but may also be of benefit in a neo-adjuvant or adjuvant setting. Significant developments in the application of targeted radionuclide therapy have taken place. New treatment modalities have been introduced in the clinic. The concept of combining therapeutic radiopharmaceuticals with other treatment modalities is more extensively explored.

Maintenance or consolidation therapy in advanced ovarian cancer.

Most patients with advanced epithelial ovarian cancer (EOC) achieve a clinical complete response (CR) or have no clinical evidence of disease after aggressive cytoreductive surgery and 6 cycles of platinum-/taxane-based chemotherapy. From the reported randomized trials using different durations or different cycles of chemotherapy, none of these showed improvement in survival beyond 6 cycles. Data from the literature do not support a relationship between the number of cycles and response or between the cumulative dose and response. In addition, no benefit in survival was detected with high-dose and intensity chemotherapy administered for a short time compared with standard-dose chemotherapy given for a longer time. However, statistically significant differences in progression-free survival were found in patients who achieved a clinically defined CR to a platinum (CDDP)-/paclitaxel-based chemotherapy and who continued single-agent paclitaxel for an extended time period. Notably, this randomized trial most likely did not offer any survival advantage, as it was closed prematurely by the Data Safety Monitoring Committee in accordance with the guidelines planned for interim analysis of primary end-points.

Preclinical pharmacokinetics and metabolism of a novel prototype DNA-PK inhibitor NU7026.

In this study we investigated the in vitro time dependence of radiosensitisation, pharmacokinetics and metabolism of NU7026, a novel inhibitor of the DNA repair enzyme DNA-dependent protein kinase (DNA-PK). At a dose of 10 muM, which is nontoxic to cells per se, a minimum NU7026 exposure of 4 h in combination with 3 Gy radiation is required for a significant radiosensitisation effect in CH1 human ovarian cancer cells. Following intravenous administration to mice at 5 mg kg(-1), NU7026 underwent rapid plasma clearance (0.108 l h(-1)) and this was largely attributed to extensive metabolism. Bioavailability following interperitoneal (i.p.) and p.o. administration at 20 mg kg(-1) was 20 and 15%, respectively. Investigation of NU7026 metabolism profiles in plasma and urine indicated that the compound undergoes multiple hydroxylations. A glucuronide conjugate of a bis-hydroxylated metabolite represented the major excretion product in urine. Identification of the major oxidation site as C-2 of the morpholine ring was confirmed by the fact that the plasma clearance of NU7107 (an analogue of NU7026 methylated at C-2 and C-6 of the morpholine ring) was four-fold slower than that of NU7026. The pharmacokinetic simulations performed predict that NU7026 will have to be administered four times per day at 100 mg kg(-1) i.p. in order to obtain the drug exposure required for radiosensitisation.

Preliminary results of nanopharmaceuticals used in the radioimmunotherapy of ovarian cancer.

PURPOSE: The treatment of late stage ovarian cancer presents an unmet clinical need for women around the world. A multistep radioimmunotherapeutic (RIT) approach, exploiting the combination of a bispecific monoclonal antibody (BsMAb) with 90Y labelled biotinylated long-circulating liposomes was tested as a potential adjuvant treatment for epithelial ovarian carcinomatosis in an attempt to meet this need. This approach was used to overcome some of the major obstacles associated with conventional strategies, in particular, to increase the amount of radioactivity delivered to the tumor site compared with conventional monoclonal antibody (MAb) radionuclide delivery. We hypothesize that sequential intraperitoneal administration of the targeting and therapeutic moieties provides the basis for an enhanced therapeutic ratio. METHODS: A BsMAb, with anti-CA 125 and anti-biotin epitopes was engineered for use with PEGylated liposomes coated with biotin to deliver the cytotoxic radionuclide 90Y to tumor sites. An in vivo therapy trial was used to test this RIT protocol with Balb/c nude mice (n=29) xenografted with the NIH:OVCAR-3 (CA 125+) human ovarian cancer cell line. RESULTS: A median tumor growth delay of 91 days for the combined treatment group versus 77.7 days for the control group was observed. CONCLUSION: An ongoing tumor growth delay/control study using this model has indicated an appreciable delay in progress of tumor and ascites development in treated vs. control populations.

[The modern organ- and function-sparing surgical treatment in oncology]. / Sovremennoe organosokhraniaiushchee i funktsional'no shchadiashchee khirurgicheskoe lechenie v onkologii.

The results of organ-sparing treatment of patients with cancers of the breast, uterine cervix, endometrium and ovary are described in the paper. A prospective randomized clinical study launched in 1995 at Petrov's Research Institute of Oncology comprised cases of above 700 patients with breast cancer, around 300 women with cancer in situ and with microinvasive cancer of the uterine cervix and 83 patients with initial endometrial cancer. The results of the above treatment (segment resection + axillar dissection + radiotherapy) were shown to be similar to those obtained after Petey-Dyson mastectomy (5-year survival of 86.7% versus 88.8%, p = 0.81). The risk of local recurrence was increasing in patients with the tumors' diameter of more than 1 cm who were not treated by radiotherapy. The total regression of tumors was registered in 70% of patients with initial endometrial cancer after hormone therapy by progestagens and antiestrogens; 20% of them maintained the reproductive function.

Response to pulsed dose rate irradiation with and without mild hyperthermia using tumour and normal cell lines.

To determine whether pulsed dose rate irradiation in combination with mild hyperthermia could radiosensitize cells in comparison to pulsed dose rate irradiation alone, human ovarian carcinoma (A2780s, cisplatin- and radiation-sensitive, and A2780cp, cisplatin- and radiation-resistant) and human fibroblast (AG1522) cell lines were used. Cells were irradiated in vitro using two fraction sizes, 0.53 Gy given every hour and 1.6 Gy given every 3h, with an overall average dose rate of 0.53 Gy/h. The data showed that 40 degrees C hyperthermia did not radiosensitize any of the cell lines for the 0.53 Gy every 1 h fractionation scheme. In addition, mild hyperthermia radiosensitized both carcinoma cell lines when using the 1.6 Gy fraction size for all doses tested in the A2780s and at higher doses in the A2780cp, but not the normal cell line. These results suggest a potential clinical advantage when using the 1.6 Gy fraction size with 40 degrees C mild hyperthermia, since hyperthermia radiosensitized the carcinoma cells but not the normal cells.

Optimal quality (131)I-monoclonal antibodies on high-dose labeling in a large reaction volume and temporarily coating the antibody with IODO-GEN.

UNLABELLED: A novel, facile procedure for efficient coupling of high doses of (131)I to monoclonal antibodies (MAbs) was developed with minimal chemical and radiation damage. METHODS: To diminish the radiation and chemical burden during labeling, iodination was performed in a large reaction volume and by temporarily coating the MAb with a minimal amount of IODO-GEN. The MAb was coated by injection of IODO-GEN (dissolved in acetonitrile [MeCN]) into the aqueous MAb solution, and the coating was subsequently removed by addition of ascorbic acid. For chemoprotection before, during, and after PD-10 purification of the (131)I-MAbs, ascorbic acid and human serum albumin were used. The effects of autoradiolysis in the starting (131)I solution were countered by treatment with NaOH and ascorbic acid. For this so-called IODO-GEN-coated MAb method, the sensitive chimeric MAb MOv18 (c-MOv18) and the more robust murine MAbs K928 and E48 were used. The high-dose (131)I-labeled MAbs were characterized for radiochemical purity and MAb integrity by thin-layer chromatography, high-performance liquid chromatography, and sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by phosphor imager quantification. The high-dose (131)I-labeled MAbs were also characterized for immunoreactivity. The radiopharmacokinetics and biodistribution of (131)I-c-MOv18 were analyzed in human tumor-bearing nude mice. For comparison, (131)I-c-MOv18 batches were made using the conventional chloramine-T or IODO-GEN-coated vial method. RESULTS: Conventional high-dose labeling of 5 mg c-MOv18 with 4.4 GBq (131)I resulted in a labeling yield of 60%, a radiochemical purity of 90%, an immunoreactive fraction of 25% (72% being the maximum in the assay used), and the presence of aggregation and degradation products. Using similar amounts of (131)I and MAb in the IODO-GEN-coated MAb method, 85%-89% overall radiochemical yield, at least 99.7% radiochemical purity, and full preservation of MAb integrity and immunoreactivity were achieved. For this labeling, 5 mg MAb were coated with 35 microg IODO-GEN during 3 min in a reaction volume of 6 mL. Also, biodistribution was optimal, and tumor accumulation was superior to that of coinjected (125)I-c-MOv18 labeled according to the conventional IODO-GEN-coated vial method. CONCLUSION: A new, facile, high-dose (131)I-labeling method was developed for production of (131)I-labeled MAbs with optimal quality for use in clinical radioimmunotherapy.