Safety and efficacy of radioimmunotherapy with Yttrium 90 ibritumomab tiuxetan (Zevalin)

Adverse reactions to therapeutic radiopharmaceuticals

Radiopharmaceuticals are drugs used in treatment or diagnosis that contain a radioactive part, usually a pharmaceutical part in their structure. Adverse drug reactions are harmful and unexpected responses that occur when administered at normal doses. Although radiopharmaceuticals are regarded as safe medical products, adverse reactions should not be ignored. More serious adverse reactions such as myelosuppression, pleural effusion, and death may develop in therapeutic radiopharmaceuticals due to their use at higher doses than those used in diagnosis. Therefore, monitoring adverse reactions and reporting them to health authorities is important. This review aims to provide information about adverse reactions that may be related to radiopharmaceuticals used in treatment.

Extracellular Vesicles-Based Drug Delivery Systems: A New Challenge and the Exemplum of Malignant Pleural Mesothelioma

Research for the most selective drug delivery to tumors represents a fascinating key target in science. Alongside the artificial delivery systems identified in the last decades (e.g., liposomes), a family of natural extracellular vesicles (EVs) has gained increasing focus for their potential use in delivering anticancer compounds. EVs are released by all cell types to mediate cell-to-cell communication both at the paracrine and the systemic levels, suggesting a role for them as an ideal nano-delivery system. Malignant pleural mesothelioma (MPM) stands out among currently untreatable tumors, also due to the difficulties in achieving an early diagnosis. Thus, early diagnosis and treatment of MPM are both unmet clinical needs. This review looks at indirect and direct evidence that EVs may represent both a new tool for allowing an early diagnosis of MPM and a potential new delivery system for more efficient therapeutic strategies. Since MPM is a relatively rare malignant tumor and preclinical MPM models developed to date are very few and not reliable, this review will report data obtained in other tumor types, suggesting the potential use of EVs in mesothelioma patients as well.

Recent Research Trends on Bismuth Compounds in Cancer Chemoand Radiotherapy

Background:

Application of coordination chemistry in nanotechnology is a rapidly developing research field in medicine. Bismuth complexes have been widely used in biomedicine with satisfactory therapeutic effects, mostly in Helicobacter pylori eradication, but also as potential antimicrobial and anti-leishmanial agents. Additionally, in recent years, application of bismuth-based compounds as potent anticancer drugs has been studied extensively.

Methods:

Search for data connected with recent trends on bismuth compounds in cancer chemo- and radiotherapy was carried out using web-based literature searching tools such as ScienceDirect, Springer, Royal Society of Chemistry, American Chemical Society and Wiley. Pertinent literature is covered up to 2016.

Results:

In this review, based on 213 papers, we highlighted a number of current problems connected with: (i) characterization of bismuth complexes with selected thiosemicarbazone, hydrazone, and dithiocarbamate classes of ligands as potential chemotherapeutics. Literature results derived from 50 papers show that almost all bismuth compounds inhibit growth and proliferation of breast, colon, ovarian, lung, and other tumours; (ii) pioneering research on application of bismuth-based nanoparticles and nanodots for radiosensitization. Results show great promise for improvement in therapeutic efficacy of ionizing radiation in advanced radiotherapy (described in 36 papers); and (iii) research challenges in using bismuth radionuclides in targeted radioimmunotherapy, connected with choice of adequate radionuclide, targeting vector, proper bifunctional ligand and problems with 213Bi recoil daughters toxicity (derived from 92 papers).

Conclusion:

This review presents recent research trends on bismuth compounds in cancer chemo- and radiotherapy, suggesting directions for future research.

Continuing pursuit for ideal systemic anticancer radiotherapeutics

Cancer is one of the major causes of death for non-transmissible chronic diseases worldwide. Conventional treatments including surgery, chemotherapy and external beam radiotherapy are generally far from curative. Complementary therapies are attempted for achieving more successful treatment response. Systemic targeted radiotherapy (STR) is a radiotherapeutic modality based on systemic administration of radioactive agents for selectively delivering high doses of energy to destroy cancer cells. For this purpose, diverse tumour-target specific agents including monoclonal antibodies (MoAb), MoAb fragments and peptides have been tested and some of them have already got FDA approval for clinical use. However, MoAbs and their tailored analogues have shown non-homogeneous tumour distribution, limited diffusion, insufficient intratumoral accumulation and retention, unwanted uptake in normal tissues and scarcity of identified cancer antigens for generating new MoAbs. Similarly, peptides have also exhibited retention in normal organs, lacks of favourable membrane permeability or drug cell internalization and short-term residence in cancer cells. Recently, a new category of target-specific agent with strong affinity for necrosis has emerged as an excellent option for developing targeted radiotherapeutic agents to be used after necrosis-inducing treatments (NITs). The combination of their high, specific and long-term accumulation and retention at necrotic sites with the crossfire effect of ionizing particle-emitters allows irradiating adjacent residual viable tumour cells during a prolonged period of time. It may considerably enhance the therapeutic response and open a new horizon for improved cancer treatability or curability.

Phase II Study of Yttrium-90–Ibritumomab Tiuxetan in Patients With Relapsed or Refractory Mantle Cell Lymphoma

Purpose

This phase II trial evaluated the safety and efficacy of yttrium-90 (90Y)–ibritumomab tiuxetan in patients with relapsed or refractory mantle cell lymphoma (MCL).

Patients and Methods

Patients with relapsed or refractory MCL were eligible for the study if they had adequate major organ function and performance status. Those with CNS disease, pleural effusion, circulating lymphoma cells ≥ 5,000/μL, or history of stem-cell transplant were ineligible. Patients with a platelet count ≥ 150,000/μL received a dose of 0.4 mCi/kg of90Y–ibritumomab tiuxetan, whereas those with a platelet count less than 150,000/μL received a dose of 0.3 mCi/kg.

Results

Thirty-four patients with a median age of 68 years (range, 52 to 79 years) received the therapeutic dose. The patients had received a median of three prior treatment regimens (range, one to six treatment regimens), including those that contained rituximab (n = 32) and bortezomib (n = 7). Of the 32 patients with measurable disease, 10 (31%) achieved complete or partial remission. After a median follow-up of 22 months (range, 2 to 72+ months), an intent-to-treat analysis revealed a median event-free survival (EFS) duration of 6 months and an overall survival duration of 21 months. The median EFS for those who achieved partial or complete remission was 28 months, while it was 3 months for those whose disease did not respond (P < .0001); it was 9 months for patients whose tumor measured less than 5 cm in the largest diameter before treatment and 3 months for those whose tumor measured ≥ 5 cm (P = .015).

Conclusion

The single-agent activity of90Y–ibritumomab tiuxetan and its favorable safety profile warrant its further development for the treatment of MCL.

Toward preparation of antibody-based imaging probe libraries for dual-modality positron emission tomography and fluorescence imaging

Two novel imaging agents trastuzumab-Cy5.5-CHX-A''1 and cetuximab-Cy7-CHX-A''2, bearing both a chelating moiety (CHX-A'') for sequestering metallic radionuclides ((86)Y or (111)In) and the near infrared dye Cy5.5/Cy7, were prepared by a novel modular synthetic strategy as examples of dual-labeled, antibody-based imaging probe library. Fluorescent microscopy illustrated that 1 and 2 strongly bind to HER2-expressing cancer cells (e.g., NIH3T3-HER2(+), SKOV-3) and to EGFR-expressing cancer cells (e.g., A431), respectively, thereby demonstrating that the functionality of the targeting moiety is conserved. Hence, the described novel synthesis strategy can be applied to engineer other tumor-targeted monoclonal antibody based probes for multimodality imaging.

[Contribution of radioimmunotherapy to the treatment of lymphoma]

Radioimmunotherapy (RIT) is an emerging treatment option for non-Hodgkin's lymphoma. Only Zevalin (Bayer Schering Pharma) radiolabeled with yttrium 90 ((90)Y) is approved in France for the treatment of adult patients with rituximab relapsed or refractory CD20+ follicular B-cell non-Hodgkin's lymphoma. This radioimmunotherapeutic agent consists of ibritumomab, a murine anti-CD20 monoclonal antibody, conjugated to the metal chelator tiuxetan for retention of the beta emitter (90)Y. This review presents the concept of RIT. The pharmacological characteristics of [(90)Y]-ibritumomab tiuxetan, the specificity of its preparation and its special precautions for use will be described. The other radionuclides and antibodies in development will also be mentioned.

Novel bimodal bifunctional ligands for radioimmunotherapy and targeted MRI

The structurally novel bifunctional ligands C-NETA and C-NE3TA, each possessing both acyclic and macrocyclic moieties, were prepared and evaluated as potential chelates for radioimmunotherapy (RIT) and targeted magnetic resonance imaging (MRI). Heptadentate C-NE3TA was fortuitously discovered during the preparation of C-NETA. An optimized synthetic method to C-NETA and C-NE3TA including purification of the polar and tailing reaction intermediates, tert-butyl C-NETA (2) and tert-butyl C-NE3TA (3) using semiprep HPLC was developed. The new Gd(III) complexes of C-NETA and C-NE3TA were prepared as contrast enhancement agents for use in targeted MRI. The T 1 relaxivity data indicate that Gd(C-NETA) and Gd(C-NE3TA) possess higher relaxivity than Gd(C-DOTA), a bifunctional version of a commercially available MRI contrast agent; Gd(DOTA). C-NETA and C-NE3TA were radiolabeled with (177)Lu, (90)Y, (203)Pb, (205/6)Bi, and (153)Gd; and in vitro stability of the radiolabeled corresponding complexes was assessed in human serum. The in vitro studies indicate that the evaluated radiolabeled complexes were stable in serum for 11 days with the exception being the (203)Pb complexes of C-NETA and C-NE3TA, which dissociated in serum. C-NETA and C-NE3TA radiolabeled (177)Lu, (90)Y, or (153)Gd complexes were further evaluated for in vivo stability in athymic mice and possess excellent or acceptable in vivo biodistribution profile. (205/6)Bi- C-NE3TA exhibited extremely rapid blood clearance and low radioactivity level at the normal organs, while (205/6)Bi- C-NETA displayed low radioactivity level in the blood and all of the organs except for the kidney where relatively high renal uptake of radioactivity is observed. C-NETA and C-NE3TA were further modified for conjugation to the monoclonal antibody Trastuzumab.

A novel bifunctional maleimido CHX-A'' chelator for conjugation to thiol-containing biomolecules

A novel bifunctional maleimido CHX-A'' DTPA chelator 5 was developed and conjugated to the monoclonal antibody trastuzumab (Herceptin) and subsequently radiolabeled with (111)In. The resulting (111)In labeled immunoconjugate 2 was demonstrated to bind to SKOV-3 ovarian cancer cells comparably to an isothiocyanato CHX-A'' DTPA modified native trastuzumab, 1. Through efficient thiol-maleimide chemistry, antibodies, peptides or other targeting vectors can now be modified with an established radioactive metal chelating agent CHX-A'' DTPA for imaging and/or therapies of cancer.

Historical development of monoclonal antibody therapeutics

Since the first publication by Kohler and Milstein on the production of mouse monoclonal antibodies (mAbs) by hybridoma technology, mAbs have had a profound impact on medicine by providing an almost limitless source of therapeutic and diagnostic reagents. Therapeutic use of mAbs has become a major part of treatments in various diseases including transplantation, oncology, autoimmune, cardiovascular, and infectious diseases. The limitation of murine mAbs due to immunogenicity was overcome by replacement of the murine sequences with their human counterpart leading to the development of chimeric, humanized, and human therapeutic antibodies. Remarkable progress has also been made following the development of the display technologies, enabling of engineering antibodies with modified properties such as molecular size, affinity, specificity, and valency. Moreover, antibody engineering technologies are constantly advancing to enable further tuning of the effector function and serum half life. Optimal delivery to the target tissue still remains to be addressed to avoid unwanted side effects as a result of systemic treatment while achieving meaningful therapeutic effect.

Rational design and generation of a bimodal bifunctional ligand for antibody-targeted radiation cancer therapy

An antibody-targeted radiation therapy (radioimmunotherapy, RIT) employs a bifunctional ligand that can effectively hold a cytotoxic metal with clinically acceptable complexation kinetics and stability while being attached to a tumor-specific antibody. Clinical exploration of the therapeutic potential of RIT has been challenged by the absence of adequate ligand, a critical component for enhancing the efficacy of the cancer therapy. To address this deficiency, the bifunctional ligand C-NETA in a unique structural class possessing both a macrocyclic cavity and a flexible acyclic moiety was designed. The practical, reproducible, and readily scalable synthetic route to C-NETA was developed, and its potential as the chelator of (212)Bi, (213)Bi, and (177)Lu for RIT was evaluated in vitro and in vivo. C-NETA rapidly binds both Lu(III) and Bi(III), and the respective metal complexes remain extremely stable in serum for 14 days. (177)Lu -C-NETA and (205/6)Bi -C-NETA possess an excellent or acceptable in vivo biodistribution profile.

Mucosal injury from targeted anti-cancer therapy

BACKGROUND

With the increased use of so-called targeted anti-cancer therapies, there has been a change in toxicities that patients are experiencing. As most targeted therapies are given in conjunction with more traditional chemotherapeutic agents, toxicities of these combination therapies are also evolving. Whilst we increasingly understand the mechanisms underlying the toxicities of chemotherapy and radiotherapy, the addition of targeted treatments requires a new understanding of both toxicity and interacting mechanisms.

AIMS

The aims of this review (which formed the basis of an invited plenary lecture at the 2006 Annual conference of the Multinational Association of Supportive Care in Cancer) were to define targeted anti-cancer therapy, to describe its known impact on the mucosa, either alone, or in combination with chemotherapy with or without radiotherapy, and finally to provide an outline for future directions in research into mucosal injury from targeted anti-cancer therapies.

METHODOLOGY

Two separate literature reviews were conducted. The combined reviews produced 700 papers of which approximately 70 were included in the review.

RESULTS

As with mucosal injury (or mucositis) in general, the studies are hampered by a lack of mucosal injury as primary endpoint, and the variable definitions and levels of reporting. The depth to which mucosal injury was studied was also inadequate. However, it is clear that the key to understanding toxicity is to understand the mechanism of action of the drug, from which it should be possible to predict the toxicities that will occur.

CONCLUSIONS

With the increasing use of targeted anti-cancer therapies, mucosal injury, particularly in its manifestations of diarrhoea, and mouth ulcers, is becoming even more prominent. More publications of basic and clinical research in this area is required.

Single-Photon Emission Computed Tomography/Computed Tomography in Lung Cancer and Malignant Lymphoma

In nuclear oncology, despite the fast-growing diffusion of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET), single-photon emission computed tomography (SPECT) studies can still play an useful clinical role in several applications. The main limitation of SPECT imaging with tumor-seeking agents is the lack of the structural delineation of the pathologic processes they detect; this drawback sometimes renders SPECT interpretation difficult and can diminish its diagnostic accuracy. Fusion with morphological studies can overcome this limitation by giving an anatomical map to scintigraphic data. In the past, software-based fusion of independently performed SPECT and CT images proved to be time-consuming and impractical for routine use. The recent development of dual-modality integrated imaging systems that provide functional (SPECT) and anatomical (CT) images in the same scanning session, with the acquired images coregistered by means of the hardware, has opened a new era in this field. The first reports indicate that SPECT/CT is very useful in cancer imaging because it is able to provide further information of clinical value in several cases. In SPECT, studies of lung cancer and malignant lymphomas using different radiopharmaceutical, hybrid images are of value in providing the correct localization of tumor sites, with a precise detection of the involved organs, and the definition of their functional status, and in allowing the exclusion of disease in sites of physiologic tracer uptake. Therefore, in lung cancer and lymphomas, hybrid SPECT/CT can play a role in the diagnosis of the primary tumor, in the staging of the disease, in the follow-up, in the monitoring of therapy, in the detection of recurrence, and in dosimetric estimations for target radionuclide therapy.

Radiopharmaceutical management of90Y/111In labeled antibodies: shielding and quantification during preparation and administration

BACKGROUND

The combined application of potent beta-emitting isotopes for therapy with remitting isotopes for scintigraphy requires a profound regimen concerning team member safety and radionuclide quantification.

METHODS

We have developed materials and methods for a proper and easy manipulation of 90Y during preparation and administration of 90Y/111In pharmaceuticals used for radioimmunotherapy.

RESULTS

The efficacy of the shielding measures is documented. Protocols for the calibration of gamma-dose calibrators with respect to 90Y are extended to the assessment of quench-corrected liquid scintillation counting of 90Y. The contribution of 90Y backscatter to 111 In counting is quantified. Newly developed shielding equipment allows an adequate administration of relatively large volumes (100 ml) of 90Y/111In labeled pharmaceuticals to patients.

CONCLUSIONS

The procedures described combine pharmaceutical (Good Manufacturing Practice) and radiation safety requirements with an accurate logging of relevant data.

Extravazation of therapeutic yttrium-90-ibritumomab tiuxetan (zevalin): a case report

The occurrence of radiation necrosis to the extravasation of therapeutic radionuclide-yttrium-90-ibritumomab tiuxetan-is described, as well as the subsequent steps taken to both address the occurrence and to prevent the re-occurrence of such an adverse event. Published reports on the extravasation of diagnostic and therapeutic radionuclides are reviewed, as are prevention and treatment protocols.

Allogeneic hematopoietic cell transplantation following conditioning with 90Y-ibritumomab-tiuxetan

Radioimmunotherapy (RIT) of relapsed lymphoma is gaining increasing importance. Especially the commercially available anti-CD20 antibody 90Y-ibritumomab tiuxetan is currently under investigation in various trials including dose escalation and autologous hematopoietic progenitor cell support. It is not clear, however, whether the implementation of this radiolabeled antibody into another treatment option for relapsed or poor risk lymphoma patients-allogeneic hematopoietic cell transplantation-interferes with or delays successful engraftment. This study reports encouraging results with 2 relapsed lymphoma patients (1 transformed marginal zone lymphoma and 1 mantle cell lymphoma) who underwent allogeneic hematopoietic cell transplantation from HLA-matched donors. The conditioning regimen consisted of Rituximab 250 mg m(-2) on days -21 and -14, 0.4 mCi kg(-1) body weight 90Y-ibritumomab tiuxetan on day -14 and fludarabine (30 mg m(-2)) plus cyclophosphamide (500 mg m(-2)) on days -7 to -3. The data demonstrate that engraftment is fast and reliable with leukocytes >1 x 10(9) L(-1) on day 12 and platelets >50 x 10(9) L(-1) on day 10. Thus, the incorporation of radioimmunotherapy into allogeneic transplant protocols combines established modalities with proven anti-lymphoma activity and, hence, offers an attractive new therapeutic option for relapsed lymphoma patients.

In vivo molecular targeted radiotherapy

Unsealed radionuclides have been in clinical therapeutic use for well over half a century. Following the early inappropriate clinical administrations of radium salts in the early 20th century, the first real clinical benefits became evident with the use of ¹³¹I-sodium iodide for the treatment of hypothyroidism and differentiated thyroid carcinoma and ³²P-sodium phosphate for the treatment of polycythaemia vera. In recent years the use of bone seeking agents ⁸⁹Sr, ¹⁵³Sm and ¹⁸⁶Re for the palliation of bone pain have become widespread and considerable progress has been evident with the use of ¹³¹I-MIBG and ⁹⁰Y-somatostatin receptor binding agents. Although the use of monoclonal antibody based therapeutic products has been slow to evolve, the start of the 21st century has witnessed the first licensed therapeutic antibody conjugates based on ⁹⁰Y and ¹³¹I for the treatment of non-Hodgkin's lymphoma. The future clinical utility of this form of therapy will depend upon the development of radiopharmaceutical conjugates capable of selective binding to molecular targets. The availability of some therapeutic radionuclides such as ¹⁸⁸Re produced from the tungsten generator system which can produce activity as required over many months, may make this type of therapy more widely available in some remote and developing countries.

Future products will involve cytotoxic radionuclides with appropriate potency, but with physical characteristics that will enable the administration of therapeutic doses with the minimal need for patient isolation. Further developments are likely to involve molecular constructs such as aptamers arising from new developments in biotechnology.

Patient trials are still underway and are now examining new methods of administration, dose fractionation and the clinical introduction of alpha emitting radiopharmaceutical conjugates. This review outlines the history, development and future potential of these forms of therapy.

Arming antibodies: prospects and challenges for immunoconjugates

Immunoconjugates--monoclonal antibodies (mAbs) coupled to highly toxic agents, including radioisotopes and toxic drugs (ineffective when administered systemically alone)--are becoming a significant component of anticancer treatments. By combining the exquisite targeting specificity of mAbs with the enhanced tumor-killing power of toxic effector molecules, immunoconjugates permit sensitive discrimination between target and normal tissue, resulting in fewer toxic side effects than most conventional chemotherapeutic drugs. Two radioimmunoconjugates, ibritumomab tiuxetan (Zevalin) and tositumomab-131I (Bexxar), and one drug conjugate, gemtuzumab ozogamicin (Mylotarg), are now on the market. For the next generation of immunoconjugates, advances in protein engineering will permit greater control of mAb targeting, clearance and pharmacokinetics, resulting in significantly improved delivery to tumors of radioisotopes and potent anticancer drugs. Pre-targeting strategies, which separate the two functions of antibody-based localization and delivery or generation of the toxic agent into two steps, also promise to afford superior tumor targeting and therapeutic efficacy. Several challenges in optimizing immunoconjugates remain, however, including poor intratumoral mAb uptake, normal tissue conjugate exposure and issues surrounding drug potency and conditional release from mAb carriers. Nonetheless, highly promising results from preclinical models will continue to drive the clinical development of this therapeutic class.

Pivotal study of iodine-131-labeled chimeric tumor necrosis treatment radioimmunotherapy in patients with advanced lung cancer

PURPOSE

Tumor necrosis treatment (TNT) uses degenerating tumor cells and necrotic regions of tumors as targets for radioimmunotherapy. Previous studies in animal tumor models and clinical trials have demonstrated that when linked to the therapeutic radionuclide iodine-131, recombinant chimeric TNT antibody ((131)I-chTNT) can deliver therapeutic doses to tumors regardless of the location or type of malignancy. Therapeutic efficacy and toxicity of (131)I-chTNT in advanced lung cancer patients were studied in this pivotal registration trial.

PATIENTS AND METHODS

Patients with advanced lung cancer were treated with systemic or intratumoral injection of (131)I-chTNT in eight oncology centers in China. The objective response rate (ORR) was assessed as the primary end point.

RESULTS

All 107 patients who were entered onto the study and completed therapy had experienced treatment failure after prior radiotherapy or chemotherapy a mean of three times. The results showed an ORR of 34.6% (complete response, 3.7%; partial response, 30.8%; no change, 55.1%; and progressive disease, 10.3%) in all patients and 33% in 97 non-small-cell lung cancer patients. A biodistribution study demonstrated excellent localization of the radioactivity in tumors in both systemically and intratumorally injected patients. The most obvious adverse side effect was mild and reversible bone marrow suppression.

CONCLUSION

Radioimmunotherapy with (131)I-chTNT was well tolerated and can be used systemically or locally to treat refractory tumors of the lung.