Hyperthermia combined with immune checkpoint inhibitor therapy: Synergistic sensitization and clinical outcomes.

BACKGROUND: Within the field of oncotherapy, research interest regarding immunotherapy has risen to the point that it is now seen as a key application. However, inherent disadvantages of immune checkpoint inhibitors (ICIs), such as their low response rates and immune-related adverse events (irAEs), currently restrict their clinical application. Were these disadvantages to be overcome, more patients could derive prolonged benefits from ICIs. At present, many basic experiments and clinical studies using hyperthermia combined with ICI treatment (HIT) have been performed and shown the potential to address the above challenges. Therefore, this review extensively summarizes the knowledge and progress of HIT for analysis and discusses the effect and feasibility. METHODS: In this review, we explored the PubMed and clinicaltrials.gov databases, with regard to the searching terms "immune checkpoint inhibitor, immunotherapy, hyperthermia, ablation, photothermal therapy". RESULTS: By reviewing the literature, we analyzed how hyperthermia influences tumor immunology and improves the efficacy of ICI. Hyperthermia can trigger a series of multifactorial molecular cascade reactions between tumors and immunization and can significantly induce cytological modifications within the tumor microenvironment (TME). The pharmacological potency of ICIs can be enhanced greatly through the immunomodulatory amelioration of immunosuppression, and the activation of immunostimulation. Emerging clinical trials outcome regarding HIT have verified and enriched the theoretical foundation of synergistic sensitization. CONCLUSION: HIT research is now starting to transition from preclinical studies to clinical investigations. Several HIT sensitization mechanisms have been reflected and demonstrated as significant survival benefits for patients through pioneering clinical trials. Further studies into the theoretical basis and practical standards of HIT, combined with larger-scale clinical studies involving more cancer types, will be necessary for the future.

Hyperthermia combined with immune checkpoint inhibitor therapy in the treatment of primary and metastatic tumors.

According to the difference in temperature, thermotherapy can be divided into thermal ablation and mild hyperthermia. The main advantage of thermal ablation is that it can efficiently target tumors in situ, while mild hyperthermia has a good inhibitory effect on distant metastasis. There are some similarities and differences between the two therapies with respect to inducing anti-tumor immune responses, but neither of them results in sustained systemic immunity. Malignant tumors (such as breast cancer, pancreatic cancer, nasopharyngeal carcinoma, and brain cancer) are recurrent, highly metastatic, and highly invasive even after treatment, hence a single therapy rarely resolves the clinical issues. A more effective and comprehensive treatment strategy using a combination of hyperthermia and immune checkpoint inhibitor (ICI) therapies has gained attention. This paper summarizes the relevant preclinical and clinical studies on hyperthermia combined with ICI therapies and compares the efficacy of two types of hyperthermia combined with ICIs, in order to provide a better treatment for the recurrence and metastasis of clinically malignant tumors.

Adjuvant 131I-metuximab for hepatocellular carcinoma after liver resection: a randomised, controlled, multicentre, open-label, phase 2 trial.

BACKGROUND: Effective adjuvant treatment after hepatectomy for hepatocellular carcinoma (HCC) is an important area of research. Radioactive iodine (131I)-labelled metuximab is a radiolabelled monoclonal antibody against the CD147 (also known as basigin or HAb18G) antigen that is expressed in HCC. We aimed to examine the role of 131I-metuximab as an adjuvant therapy after HCC resection. METHODS: This randomised, controlled, multicentre, open-label, phase 2 trial was done at five medical centres in China. Patients aged 18-75 years who underwent curative-intent resection of histologically confirmed HCC expressing CD147 were randomly assigned (1:1) by a computer-generated random sequence, stratified by centre, to receive either adjuvant transarterial injection of one dose of 27·75 MBq/kg 131I-metuximab 4-6 weeks after the hepatectomy (treatment group) or no adjuvant treatment (control group). Patients and physicians were not masked to the study groups. The primary outcome was 5-year recurrence-free survival (RFS) in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT00819650. FINDINGS: Between April 1, 2009, and Nov 30, 2012, 485 patients were screened for eligibility. 329 (68%) of these patients were excluded and 156 (32%) were randomly assigned to receive either 131I-metuximab (n=78) or no adjuvant treatment (n=78). The median follow-up was 55·9 months (IQR 18·6-79·4). In the intention-to-treat population, the 5-year RFS was 43·4% (95% CI 33·6-55·9) in the 131I-metuximab group and 21·7% (14·2-33·1) in the control group (hazard ratio 0·49 [95% CI 0·34-0·72]; Z=2·96, p=0·0031). 131I-metuximab-associated adverse events occurred within the first 4 weeks in 34 (45%) of 76 patients, seven (21%) of whom had grade 3 or 4 adverse events. These adverse events were all resolved with appropriate treatment within 2 weeks of being identified. INTERPRETATION: Adjuvant 131I-metuximab treatment significantly improved the 5-year RFS of patients after hepatectomy for HCC tumours expressing CD147. This treatment was well tolerated by patients. FUNDING: State Key Project on Infectious Diseases of China.

Trastuzumab Conjugated Superparamagnetic Iron Oxide Nanoparticles Labeled with 225Ac as a Perspective Tool for Combined α-Radioimmunotherapy and Magnetic Hyperthermia of HER2-Positive Breast Cancer.

It has been proven and confirmed in numerous repeated tests, that the use of a combination of several therapeutic methods gives much better treatment results than in the case of separate therapies. Particularly promising is the combination of ionizing radiation and magnetic hyperthermia in one drug. To achieve this objective, magnetite nanoparticles have been modified in their core with α emitter 225Ac, in an amount affecting only slightly their magnetic properties. By 3-phosphonopropionic acid (CEPA) linker nanoparticles were conjugated covalently with trastuzumab (Herceptin®), a monoclonal antibody that recognizes ovarian and breast cancer cells overexpressing the HER2 receptors. The synthesized bioconjugates were characterized by transmission electron microscopy (TEM), Dynamic Light Scattering (DLS) measurement, thermogravimetric analysis (TGA) and application of 131I-labeled trastuzumab for quantification of the bound biomolecule. The obtained results show that one 225Ac@Fe3O4-CEPA-trastuzumab bioconjugate contains an average of 8-11 molecules of trastuzumab. The labeled nanoparticles almost quantitatively retain 225Ac (>98%) in phosphate-buffered saline (PBS) and physiological salt, and more than 90% of 221Fr and 213Bi over 10 days. In human serum after 10 days, the fraction of 225Ac released from 225Ac@Fe3O4 was still less than 2%, but the retention of 221Fr and 213Bi decreased to 70%. The synthesized 225Ac@Fe3O4-CEPA-trastuzumab bioconjugates have shown a high cytotoxic effect toward SKOV-3 ovarian cancer cells expressing HER2 receptor in-vitro. The in-vivo studies indicate that this bioconjugate exhibits properties suitable for the treatment of cancer cells by intratumoral or post-resection injection. The intravenous injection of the 225Ac@Fe3O4-CEPA-trastuzumab radiobioconjugate is excluded due to its high accumulation in the liver, lungs and spleen. Additionally, the high value of a specific absorption rate (SAR) allows its use in a new very perspective combination of α radionuclide therapy with magnetic hyperthermia.

Preclinical Combination Studies of an FGFR2 Targeted Thorium-227 Conjugate and the ATR Inhibitor BAY 1895344.

PURPOSE: Fibroblast growth factor receptor 2 (FGFR2) has been previously reported to be overexpressed in several types of cancer, whereas the expression in normal tissue is considered to be moderate to low. Thus, FGFR2 is regarded as an attractive tumor antigen for targeted alpha therapy. This study reports the evaluation of an FGFR2-targeted thorium-227 conjugate (FGFR2-TTC, BAY 2304058) comprising an anti-FGFR2 antibody, a chelator moiety covalently conjugated to the antibody, and the alpha particle-emitting radionuclide thorium-227. FGFR2-TTC was assessed as a monotherapy and in combination with the DNA damage response inhibitor ATRi BAY 1895344. METHODS AND MATERIALS: The in vitro cytotoxicity and mechanism of action were evaluated by determining cell viability, the DNA damage response marker γH2A.X, and cell cycle analyses. The in vivo efficacy was determined using human tumor xenograft models in nude mice. RESULTS: In vitro mechanistic assays demonstrated upregulation of γH2A.X and induction of cell cycle arrest in several FGFR2-expressing cancer cell lines after treatment with FGFR2-TTC. In vivo, FGFR2-TTC significantly inhibited tumor growth at a dose of 500 kBq/kg in the xenograft models NCI-H716, SNU-16, and MFM-223. By combining FGFR2-TTC with the ATR inhibitor BAY 1895344, an increased potency was observed in vitro, as were elevated levels of γH2A.X and inhibition of FGFR2-TTC-mediated cell cycle arrest. In the MFM-223 tumor xenograft model, combination of the ATRi BAY 1895344 with FGFR2-TTC resulted in significant tumor growth inhibition at doses at which the single agents had no effect. CONCLUSIONS: The data provide a mechanism-based rationale for combining the FGFR2-TTC with the ATRi BAY 1895344 as a new therapeutic approach for treatment of FGFR2-positive tumors from different cancer indications.

64Cu-Intraperitoneal Radioimmunotherapy: A Novel Approach for Adjuvant Treatment in a Clinically Relevant Preclinical Model of Pancreatic Cancer.

Pancreatic cancer (PC) has a very poor prognosis. Surgery is the primary treatment for patients with resectable PC; however, local recurrence, hepatic metastasis, and peritoneal dissemination often occur even after extensive surgery. Adjuvant chemotherapy, typically with gemcitabine, has been used clinically but with only a modest survival benefit. To achieve a better outcome, we investigated the efficacy of 64Cu-intraperitoneal radioimmunotherapy (ipRIT) with 64Cu-labeled antiepidermal growth factor receptor antibody cetuximab as an adjuvant treatment after PC surgery using an orthotopic xenografted mouse model. Methods: The efficacy of adjuvant 64Cu-ipRIT was investigated in a human PC mouse model harboring orthotopic xenografts of xPA-1-DC cells. To reproduce the clinical situation, PC xenografts were surgically resected when pancreatic tumors were readily visible but not metastatic tumors. Increasing doses of 64Cu-cetuximab were intraperitoneally injected, and the mice were monitored for toxicity to determine the safe therapeutic dose. For adjuvant 64Cu-ipRIT, the day after tumor resection, the mice were intraperitoneally administered 22.2 MBq of 64Cu-PCTA-cetuximab and the survival was compared with that in surgery-only controls. For comparison, adjuvant chemotherapy with gemcitabine was also examined using the same model. Results: The mouse model not only developed primary tumors in the pancreas but also subsequently reproduced local recurrence, hepatic metastasis, and peritoneal dissemination after surgery, which is similar to the manifestations that occur with human PC. Adjuvant 64Cu-ipRIT with 64Cu-labeled cetuximab after surgery effectively suppressed local recurrence, hepatic metastasis, and peritoneal dissemination in this model. Significant improvement of the survival with minimal toxicity was achieved by adjuvant 64Cu-ipRIT compared with that in control mice that underwent surgery only. Adjuvant chemotherapy with gemcitabine nominally prolonged the survival, but the effect was not statistically significant. Conclusion:64Cu-ipRIT with cetuximab can be an effective adjuvant therapy after PC surgery.

Targeted radioimmunotherapy for embryonal tumor with multilayered rosettes.

PURPOSE: We explored the use of intraventricular 131I-Omburtamab targeting B7-H3 in patients with ETMR. METHODS: Patients were enrolled in an IRB approved, phase 1, 3 + 3 dose escalation trial. Patients with CNS disease expressing the antibody target antigen B7-H3 were eligible. We report on a cohort of three patients with ETMR who were enrolled on the study. Three symptomatic children (ages 14 months, 3 and 3.5 years) had large parietal masses confirmed to be B7-H3-reactive ETMR. Patients received 2 mCi 131I-Omburtamab as a tracer followed by one or two therapeutic 131I-Omburtamab injections. Dosimetry was based on serial CSF, blood samplings and region of interest (ROI) on nuclear scans. Brain and spine MRIs and CSF cytology were done at baseline, 5 weeks after 131I-Omburtamab, and approximately every 3 months thereafter. Acute toxicities and survival were noted. RESULTS: Patients received surgery, focal radiation, and high dose chemotherapy. Patients 1 and 2 received 131I-Omburtamab (80 and 53 mCi, respectively). Patient 3 had a local recurrence prior to 131I-Omburtamab treated with surgery, external beam radiation, chemotherapy, then 131I-Omburtamab (36 mCi). 131I-Omburtamab was well-tolerated. Mean dose delivered by 131I-Omburtamab was 68.4 cGy/mCi to CSF and 1.95 cGy/mCi to blood. Mean ROI doses were 230.4 (ventricular) and 58.2 (spinal) cGy/mCi. Patients 1 and 2 remain in remission 6.8 years and 2.3 years after diagnosis, respectively; patient 3 died of progressive disease 7 months after therapy (2 years after diagnosis). CONCLUSIONS: 131I-Omburtamab appears safe with favorable dosimetry therapeutic index. When used as consolidation following surgery and chemoradiation therapy, 131I-Omburtamab may have therapeutic benefit for patients with ETMR.

Targeting angiogenesis for radioimmunotherapy with a 177Lu-labeled antibody.

PURPOSE: Increased angiogenesis is a marker of aggressiveness in many cancers. Targeted radionuclide therapy of these cancers with angiogenesis-targeting agents may curtail this increased blood vessel formation and slow the growth of tumors, both primary and metastatic. CD105, or endoglin, has a primary role in angiogenesis in a number of cancers, making this a widely applicable target for targeted radioimmunotherapy. METHODS: The anti-CD105 antibody, TRC105 (TRACON Pharmaceuticals), was conjugated with DTPA for radiolabeling with 177Lu (t 1/2 6.65 days). Balb/c mice were implanted with 4T1 mammary carcinoma cells, and five study groups were used: 177Lu only, TRC105 only, 177Lu-DTPA-IgG (a nonspecific antibody), 177Lu-DTPA-TRC105 low-dose, and 177Lu-DTPA-TRC105 high-dose. Toxicity of the agent was monitored by body weight measurements and analysis of blood markers. Biodistribution studies of 177Lu-DTPA-TRC105 were also performed at 1 and 7 days after injection. Ex vivo histology studies of various tissues were conducted at 1, 7, and 30 days after injection of high-dose 177Lu-DTPA-TRC105. RESULTS: Biodistribution studies indicated steady uptake of 177Lu-DTPA-TRC105 in 4T1 tumors between 1 and 7 days after injection (14.3 ± 2.3%ID/g and 11.6 ± 6.1%ID/g, respectively; n = 3) and gradual clearance from other organs. Significant inhibition of tumor growth was observed in the high-dose group, with a corresponding significant increase in survival (p < 0.001, all groups). In most study groups (all except the nonspecific IgG group), the body weights of the mice did not decrease by more than 10%, indicating the safety of the injected agents. Serum alanine transaminase levels remained nearly constant indicating no damage to the liver (a primary clearance organ of the agent), and this was confirmed by ex vivo histological analyses. CONCLUSION: 177Lu-DTPA-TRC105, when administered at a sufficient dose, is able to curtail tumor growth and provide a significant survival benefit without off-target toxicity. Thus, this targeted agent could be used in combination with other treatment options to slow tumor growth allowing the other agents to be more effective.

Repeated adjuvant anti-CEA radioimmunotherapy after resection of colorectal liver metastases: Safety, feasibility, and long-term efficacy results of a prospective phase 2 study.

BACKGROUND: In previous work, a single administration of anticarcinoembryonic antigen (anti-CEA) 131 I-labetuzumab radioimmunotherapy (RIT) after complete resection of colorectal liver metastases was well tolerated and significantly improved survival compared with controls. In the current phase 2 trial, the authors studied repeated RIT in the same setting, examining safety, feasibility, and efficacy. METHODS: Sixty-three patients (median age, 64.5 years) received RIT at 40 to 50 millicuries/m2 per dose. Before the receipt of RIT, restaging was performed with computed tomography/magnetic resonance imaging and 18 F-fluorodeoxyglucose-positron emission to confirm that patients were "truly adjuvant." Patients who had elevated serum CEA levels or radiographically inconclusive new lesions were classified as "possibly nonadjuvant," but they also received RIT. Time to progression (TTP), overall survival (OS), and cause-specific survival (CSS) were calculated. The median follow-up was 54 months. RESULTS: After the first course of RIT, 14 of 63 patients experienced National Cancer Institute Common Toxicity Criteria grade 4 hematotoxicity; 19 patients did not receive the second course of RIT because of impaired performance status (N = 5) or relapse (N = 14). After the second course of RIT, 9 of 44 patients experienced National Cancer Institute Common Toxicity Criteria grade 4 hematotoxicity. Five patients developed myelodysplastic syndrome (MDS) from 22 to 55 months after their last RIT. The median TTP, OS, and CSS for all patients were 16, 55, and 60 months, respectively. The "truly adjuvant" patients (N = 39) had an improved median TTP (not reached vs 6.1 months; hazard ratio, 0.12; P < .001), OS (75.6 vs 33.4 months; hazard ratio, 0.44; P = .014), and CSS (not reached vs 41.4 months; hazard ratio,0.42; P = .014) compared with "possibly nonadjuvant" patients (N = 24). CONCLUSIONS: Repeated RIT with 131 I-labetuzumab is feasible but is associated with hematotoxicity. Survival is very encouraging, especially for "truly adjuvant" patients. However, the maximum safe dose of 131 I-labetuzumab is a single administration of 50 millicuries/m2 . Cancer 2017;123:638-649. © 2016 American Cancer Society.

Triple Therapy of HER2+ Cancer Using Radiolabeled Multifunctional Iron Oxide Nanoparticles and Alternating Magnetic Field.

By using radio-labeled multifunctional superparamagnetic iron oxide nanoparticles (SPIONs) and an alternating magnetic field (AMF), we carried out targeted hyperthermia, drug delivery, radio-immunotherapy (RIT), and controlled chemotherapy of cancer tumors. We synthesized and characterized Indium-111-labeled, Trastuzumab and Doxorubicin (DOX)-conjugated APTES-PEG-coated SPIONs in our previous work. Then, we evaluated their capability in SPECT/MRI (single photon emission computed tomography/magnetic resonance imaging) dual modal molecular imaging, targeting, and controlled release. In this research, AMF was introduced to evaluate therapeutic effects of magnetic hyperthermia on radionuclide-chemo therapy of HER2+ cells and tumor (HER2+)-bearing mice. In vitro and in vivo experiments using synthesized complex were repeated under an AMF (f: 100 KHz, H: 280 Gs). Instead of an intra-tumor injection in most hyperthermia experiments, SPIONs were injected to the tail vein, based on our delivery strategies. For magnetic delivery, we held a permanent Nd-B-Fe magnet near the tumor region. The results showed that simultaneous magnetic hyperthermia enhanced SKBR3 cancer cells, killing by 24%, 28%, 33%, and 80% at 48 hours post-treatment for treated cells with (1) bare SPIONs; (2) antibody-conjugated, DOX-free, surface-modified SPIONs; (3) 111In-labeled, antibody-conjugated surface-modified SPIONs; and (4) 111In-labeled, antibody- and DOX-conjugated surface-modified SPIONs, respectively. Moreover, tumor volume inhibitory rate was 85% after a 28 day period of treatment. By using this method, multimodal imaging-guided, targeted hyperthermia, RIT, and controlled chemotherapy could be achievable in the near future.

New insights into the pretargeting approach to image and treat tumours.

Tumour pretargeting is a promising strategy for cancer diagnosis and therapy allowing for the rational use of long circulating, highly specific monoclonal antibodies (mAbs) for both non-invasive cancer radioimmunodetection (RID) and radioimmunotherapy (RIT). In contrast to conventional RID/RIT where the radionuclides and oncotropic vector molecules are delivered as presynthesised radioimmunoconjugates, the pretargeting approach is a multistep procedure that temporarily separates targeting of certain tumour-associated antigens from delivery of diagnostic or therapeutic radionuclides. In principle, unlabelled, highly tumour antigen specific mAb conjugates are, in a first step, administered into a patient. After injection, sufficient time is allowed for blood circulation, accumulation at the tumour site and subsequent elimination of excess mAb conjugates from the body. The small fast-clearing radiolabelled effector molecules with a complementary functionality directed to the prelocalised mAb conjugates are then administered in a second step. Due to its fast pharmacokinetics, the small effector molecules reach the malignant tissue quickly and bind the local mAb conjugates. Thereby, corresponding radioimmunoconjugates are formed in vivo and, consequently, radiation doses are deposited mainly locally. This procedure results in a much higher tumour/non-tumour (T/NT) ratio and is favourable for cancer diagnosis and therapy as it substantially minimises the radiation damage to non-tumour cells of healthy tissues. The pretargeting approach utilises specific non-covalent interactions (e.g. strept(avidin)/biotin) or covalent bond formations (e.g. inverse electron demand Diels-Alder reaction) between the tumour bound antibody and radiolabelled small molecules. This tutorial review descriptively presents this complex strategy, addresses the historical as well as recent preclinical and clinical advances and discusses the advantages and disadvantages of different available variations.

Synthesis of Site-Specific Radiolabeled Antibodies for Radioimmunotherapy via Genetic Code Expansion.

Radioimmunotherapy (RIT) delivers radioisotopes to antigen-expressing cells via monoantibodies for the imaging of lesions or medical therapy. The chelates are typically conjugated to the antibody through cysteine or lysine residues, resulting in heterogeneous chelate-to-antibody ratios and various conjugation sites. To overcome this heterogeneity, we have developed an approach for site-specific radiolabeling of antibodies by combination of genetic code expansion and click chemistry. As a proof-of-concept study, model systems including anti-CD20 antibody rituximab, positron-emitting isotope 64Cu, and a newly synthesized bifunctional linker (4-dibenzocyclooctynol-1,4,7,10-tetraazacyclotetradecane-1,4,7,10-tetraacetic acid, DIBO-DOTA) were used. The approach consists of three steps: (1) site-specific incorporation of an azido group-bearing amino acid (NEAK) via the genetic code expansion technique at the defined sites of the antibody as a "chemical handle"; (2) site-specific and quantitative conjugation of bifunctional linkers with the antibodies under a mild condition; and (3) radiolabeling of the chelate-modified antibodies with the appropriate isotope. We used heavy-chain A122NEAK rituximab as proof-of-concept and obtained a homogeneous radioconjugate with precisely two chelates per antibody, incorporated only at the chosen sites. The conjugation did not alter the binding and pharmacokinetics of the rituximab, as indicated by in vitro assays and in vivo PET imaging. We believe our research is a good supplement to the genetic code expansion technique for the development of novel radioimmunoconjugates.

A pioneer experience in Malaysia on In-house Radio-labelling of (131)I-rituximab in the treatment of Non-Hodgkin's Lymphoma and a case report of high dose (131)I-rituximab-BEAM conditioning autologous transplant.

Radioimmunotherapy is an established treatment modality in Non-Hodgkin's lymphoma. The only two commercially available radioimmunotherapies - (90)Y-ibritumomab tiuxetan is expensive and (131)I-tositumomab has been discontinued from commercial production. In resource limited environment, self-labelling (131)I-rituximab might be the only viable practical option. We reported our pioneer experience in Malaysia on self-labelling (131)I-rituximab, substituting autologous haematopoietic stem cell transplantation (HSCT) and a patient, the first reported case, received high dose (131)I-rituximab (6000MBq/163mCi) combined with BEAM conditioning for autologous HSCT.

Evolving Role of Radiopharmaceuticals in Hepatocellular Carcinoma Treatment.

The global incidence of primary liver cancer has been increased during recent decades. Among the primary liver malignancies, hepatocellular carcinoma (HCC) is recognized as the most prevalent and aggressive. Although HCC has come to be regarded as a radioresponsive tumor during the last decade, it has also been noted that the ability to deliver destructive radioactive doses exclusively to HCC is limited with conventional external irradiation techniques. This review examines a number of radiotherapeutic techniques used to treat HCC, and the radiopharmaceuticals associated with those techniques. Selective internal radiotherapy (SIRT) is a powerful therapeutic technique developed during recent decades that is increasingly used in HCC treatment due to its superior ability to target and destroy cancer cells while sparing normal tissue. The radiopharmaceuticals used in SIRT are usually comprised of a simple ion and a complex or a carrier. Transarterial radioembolization (TARE) is a technique that is increasingly used in adjuvant or neoadjuvant therapy following the surgical treatment of HCC, as well as the treatment of unresectable or untransplantable HCC. The primary radiopharmaceuticals used in TARE include Iodine- 131-labeled Lipiodol and Yttrium-90 microspheres. Radioimmunotherapy (RAIT) is currently used as targeted procedure for adjuvant therapy and combination therapy of HCC. The primary radiopharmaceutical used in RAIT is 131I-metuximab. Interstitial brachytherapy has also been the subject of recent HCC treatment investigations. The primary radiopharmaceuticals used in interstitial brachytherapy are implanted iodine-125 seed strands. This review surveys the important milestones in the development and clinical implementation of the radiopharmaceuticals used in HCC therapy and critically examines new and emerging trends for the delivery of radiopharmaceuticals to HCC tissues.

Radioimmunotherapy and Autologous Stem-Cell Transplantation in the Treatment of B-Cell Non-Hodgkin Lymphoma.

High-dose chemotherapy and autologous stem-cell transplantation (ASCT) is the standard therapy for patients with chemosensitive-relapsed or chemosensitive-refractory aggressive lymphoma. The use of rituximab, an anti-CD20 monoclonal antibody, has dramatically changed the outcome of patients with aggressive lymphoma, increasing both response and survival rates. However, despite this progress a significant proportion of patients are still refractory or relapse after frontline rituximab-containing therapy. Moreover, it is increasingly more difficult to rescue these patients with current salvage chemotherapy and ASCT approaches. Novel approaches are needed for these high-risk patients, especially in the rituximab era. Radioimmunotherapy (RIT) is a form of targeted therapy using the parent monoclonal antibody to deliver radiation emitted by a conjugated radioisotope, to the vicinity of antigen-positive tissues. Two radioimmunoconjugates--yttrium-90 ibritumomab tiuxetan (Zevalin) and iodine-131 tositumomab (Bexxar) have been in clinical use. There are multiple studies demonstrating the safety and efficacy of both agents in both indolent and aggressive lymphoma. Radiolabeled antibodies are ideal candidates to combine with high-dose chemotherapy and ASCT. RIT targets radiation to disease sites while limiting exposure of uninvolved critical organs, thus it can safely replace total-body irradiation during conditioning for ASCT. The major toxicity and limiting factor in RIT is myelotoxicity that is easily reversed by stem-cell rescue. RIT can be combined at standard doses with high-dose chemotherapy or can be given in escalated doses either alone or with high-dose chemotherapy before ASCT. Several phase II studies have shown the safety and potential efficacy of both agents using these approaches. A small randomized study comparing standard-dose Zevalin with combination of carmustine, etoposide, cytarabine, and melphalan (BEAM) high-dose chemotherapy and BEAM alone suggested a survival advantage of Zevalin-BEAM. However, a large randomized study comparing Bexxar-BEAM and rituximab-BEAM did not show any advantage. More studies are needed to establish the role and the dose of RIT given for ASCT.

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.

Preclinical testing of radiopharmaceuticals for novel applications in HIV, bacterial and fungal infectious diseases.

Antibiotics, antifungal and antiviral medications have traditionally been used in the management of infections. Due to widespread emergence of resistance to antimicrobial medications, and their side effects, there is a growing need for alternative approaches for management of such conditions. Antibiotic resistant bacterial pathogens are on the rise. A cure has not been achieved for viral infections like AIDS, while fungal and parasitic infections are constant threats to the health of general public. The incidence of opportunistic infections in immunocompromised individuals like HIV patients, patients receiving high dose steroids, chemotherapy patients, and organ transplant recipients is on the rise. Radioimmunotherapy (RIT) has the potential to be a suitable and viable therapeutic modality in the arena of infection management. Provided the target-associated antigen is expressed by the target cells and minimally or not expressed by other tissues, selective targeting of radiation to target sites can be theoretically accomplished with relative sparing normal tissues from radiation exposure. In our laboratory we successfully demonstrated the effectiveness of RIT for treating infectious diseases. We targeted murine cryptococcosis with a mAb to the Cryptococcus neoformans capsular glucuronoxylomannan labeled with Bismuth-213 ((213)Bi) or Rhenium-188 ((188)Re). We subsequently extended the applicability of RIT for treating bacterial and viral infections. One of the advantages of using RIT to treat infections as opposed to cancer is that, in contrast to tumor cells, cells expressing microbial antigens are antigenically very different from host tissues and thus provide the potential for exquisite specificity and low cross-reactivity. Ever increasing incidence of infectious pathologies, exhaustion of antimicrobial possibilities and rising drug resistance calls for use of alternative and novel therapeutic options and we believe RIT is the need of the hour to combat these infections.

Radioimmunoconjugates for the treatment of cancer.

Radioimmunotherapy (RIT) has been developed for more than 30 years. Two products targeting the CD20 antigen are approved in the treatment of non-Hodgkin B-cell lymphoma (NHBL): iodine 131-tositumomab and yttrium 90-ibritumomab tiuxetan. RIT can be integrated in clinical practice for the treatment of patients with relapsed or refractory follicular lymphoma (FL) or as consolidation after induction chemotherapy. High-dose treatment, RIT in first-line treatment, fractionated RIT, and use of new humanized monoclonal antibodies (MAbs), in particular targeting CD22, showed promising results in NHBL. In other hemopathies, such as multiple myeloma, efficacy has been demonstrated in preclinical studies. In solid tumors, more resistant to radiation and less accessible to large molecules such as MAbs, clinical efficacy remains limited. However, pretargeting methods have shown clinical efficacy. Finally, new beta emitters such as lutetium 177, with better physical properties will further improve the safety of RIT and alpha emitters, such as bismuth 213 or astatine 211, offer the theoretical possibility to eradicate the last microscopic clusters of tumor cells, in the consolidation setting. Personalized treatments, based on quantitative positron emission tomography (PET), pre-therapeutic imaging, and dosimetry procedures, also could be applied to adapt injected activity to each patient.

Yttrium 90-ibritumomab tiuxetan plus rituximab maintenance as initial therapy for patients with high-tumor-burden follicular lymphoma: a Wisconsin Oncology Network study.

INTRODUCTION: Yttrium 90-ibritumomab tiuxetan (90Y-IT) radioimmunotherapy has proved to be effective in relapsed follicular lymphoma (FL). We conducted a clinical trial in which 90Y-IT followed by maintenance rituximab (MR) was evaluated as initial therapy for high-tumor-burden FL. METHODS: Eligible patients had histologically confirmed FL and met the GELF (Groupe d'Etude des Lymphomes Folliculaires) criteria for high tumor burden. All patients received a single dose of 90Y-IT. Patients with platelet counts of 150,000/mm³ or higher received 0.4 mCi/kg, and patients with platelet counts between 100,000/mm³ and 149,000/mm³ received 0.3 mCi/kg. At 6 months, patients without progressive disease (PD) received rituximab weekly for 4 weeks at a dose of 375 mg/m² (consolidation therapy), followed by MR consisting of the same dose every 3 months for a planned 5 years. RESULTS: From January 2005 through November 2007, a total of 16 patients were enrolled. The median age was 52 years (range, 37-75). The major toxicity from 90Y-IT was myelosuppression, with 88% and 31% of the patients experiencing grade 3 and grade 4 hematologic toxicity, respectively. The responses to 90Y-IT induction therapy were as follows: 7 patients with complete response/unconfirmed complete response (CR/Cru), 4 with partial response (PR), 3 with stable disease (SD), and 2 with progressive disease (PD). We identified 6 patients with early PD (range, 4-16 months) and 10 patients with prolonged remission (range, 37-101+ months). Compared with the patients who had prolonged remission, the patients who had early PD tended to have larger baseline nodal masses. The median progression-free survival (PFS) has not been reached after a median follow-up period of 48 months. The 3-year PFS and overall survival (OS) rates were 56% (95% CI, 37%-87%) and 93% (95% CI, 80%-100%), respectively. CONCLUSION: The overall response rate (ORR) to 90Y-IT was 69% in patients who had previously untreated, high-tumor-burden FL, which is lower than what is observed with contemporary rituximab/chemotherapy combinations. MR after 90Y-IT did convert all PRs to CRs. Alternative therapies should be considered for patients who have FL with large nodal masses (>9 cm), whereas very durable responses are possible in patients who have intermediate-size masses (>9 cm).

Impact of α-targeted radiation therapy on gene expression in a pre-clinical model for disseminated peritoneal disease when combined with paclitaxel.

To better understand the molecular basis of the enhanced cell killing effected by the combined modality of paclitaxel and ²¹²Pb-trastuzumab (Pac/²¹²Pb-trastuzumab), gene expression in LS-174T i.p. xenografts was investigated 24 h after treatment. Employing a real time quantitative PCR array (qRT-PCR array), 84 DNA damage response genes were quantified. Differentially expressed genes following therapy with Pac/²¹²Pb-trastuzumab included those involved in apoptosis (BRCA1, CIDEA, GADD45α, GADD45γ, GML, IP6K3, PCBP4, PPP1R15A, RAD21, and p73), cell cycle (BRCA1, CHK1, CHK2, GADD45α, GML, GTSE1, NBN, PCBP4, PPP1R15A, RAD9A, and SESN1), and damaged DNA repair (ATRX, BTG2, EXO1, FEN1, IGHMBP2, OGG1, MSH2, MUTYH, NBN, PRKDC, RAD21, and p73). This report demonstrates that the increased stressful growth arrest conditions induced by the Pac/²¹²Pb-trastuzumab treatment suppresses cell proliferation through the regulation of genes which are involved in apoptosis and damaged DNA repair including single and double strand DNA breaks. Furthermore, the study demonstrates that ²¹²Pb-trastuzumab potentiation of cell killing efficacy results from the perturbation of genes related to the mitotic spindle checkpoint and BASC (BRCA1-associated genome surveillance complex), suggesting cross-talk between DNA damage repair and the spindle damage response.