Radioimmunotherapy: a specific treatment protocol for cancer by cytotoxic radioisotopes conjugated to antibodies. ScientificWorldJournal. 2014;2014:492061. [PMID: 25379535 PMCID: PMC4213411 DOI: 10.1155/2014/492061]

Harnessing nanoparticles and bioorthogonal chemistries for improving precision of nuclear medicine

The convergence of nanotechnology, radiopharmaceutical development and molecular imaging has unveiled exciting opportunities for the progress of innovative diagnostic and therapeutic strategies, paving the way for significant advancements in biomedical research, especially in relation to cancer. For example, the use of highly sensitive and quantitative nuclear imaging techniques including PET and SPECT, together with nanoparticles for tumour imaging and therapy has recently expanded rapidly. While the long circulating properties of many nanomaterials are beneficial for prodrug chemotherapy formulations, due to the constant decay processes involved in nuclear medicines, directly labelled materials result in prolonged systemic radiation exposure and reduced therapeutic indices due to the unfavourable target-to-background ratios. This is due to the tendency for long circulating nanomaterials to distribute within the blood to other organs, such as the liver and spleen. The recent integration of bioorthogonal chemistry with nanotechnology and molecular imaging/radiotherapy has revolutionized the field by allowing the decoupling of the targeting molecule (i.e. nanomaterial with a bioorthogonal tag) and the imaging/therapeutic radioisotope. In this way, the detection/therapeutic element can be administered as a secondary "chase" molecule that contains the bioorthogonal partner, thereby creating an avenue to improve therapeutic index and provide imaging and treatments with reduced risk. This review will provide an overview of the progress made thus far in the field of nuclear imaging and radiotherapy for cancer using the combination of nanomaterials and bioorthogonal chemistry. We also provide a critical evaluation of the challenges and opportunities for using these approaches to better understand disease and treatment mechanisms, with the potential for downstream clinical translation.

Assessing the Clinical Effectiveness of Radioimmunotherapy with Combined Radionuclide/Monoclonal Antibody Conjugates in Cancer Treatment: Insights from Randomised Clinical Trials

Background: Despite the development of advanced cancer therapies, achieving cancer eradication remains challenging. Radioimmunotherapy (RIT) is an innovative approach that combines radionuclides with monoclonal antibodies targeting tumour-associated antigens or those expressed by the tumour microenvironment. Over the past two decades, RIT has been extensively researched, along with two RIT products-90Y-ibritumomab tiuxetan and 131I-tositumomab. However, despite its demonstrated efficacy in non-solid tumours, RIT's clinical use remains limited, and its effectiveness in solid tumours is inconclusive. This study aimed to analyse randomised controlled trials (RCTs) to evaluate the overall clinical effectiveness of RIT across different cancer types and its impact on treatment outcomes. Methods: A systematic search of PubMed, EMBASE, Scopus, CENTRAL, and Google Scholar was conducted from January 2000 to October 2024 in accordance with PRISMA guidelines and the PICOS framework. Studies were included if they were RCTs evaluating RIT for cancer treatment and reported treatment outcomes such as overall survival (OS), progression-free survival (PFS), disease-free survival, or time to progression (TTP). Data extraction was performed using a standardised Excel form, and study quality was assessed with the Joanna Briggs Institute Critical Appraisal Tool for RCTs. A narrative synthesis of the data was complemented by meta-analyses where feasible, particularly for progression- and survival-related endpoints. Results: Out of 2241 records identified, 20 RCTs encompassing approximately 3562 patients were included. The majority of trials focused on non-solid tumours, particularly non-Hodgkin's lymphoma (NHL), while a smaller subset evaluated solid tumours such as lung, pancreatic, ovarian, and prostate cancers. Most non-solid tumour studies employed 90Y-ibritumomab tiuxetan or 131I-tositumomab, targeting the CD20 antigen, whereas limited evidence exists for RIT efficacy in solid tumours. Meta-analysis of progression-related outcomes yielded a pooled hazard ratio (HR) of 0.48 (95% CI: 0.39-0.59), indicating a 52% reduction in the risk of progression. In contrast, overall survival outcomes were more variable, with a pooled OS HR of 0.80 (95% CI: 0.60-1.07). Adverse events, predominantly haematological and nonhaematological toxicities, were common yet generally reversible. The findings suggest that RIT, especially when used as part of combination regimens, significantly improves treatment outcomes in non-solid tumours but has an inconsistent effect in solid tumour settings. Conclusions: The results underscore the clinical promise of RIT in treating non-solid tumours like NHL, where combination regimens yield superior outcomes compared to monotherapy. However, the inconclusive evidence in solid tumours highlights the need for further large-scale, well-designed RCTs to define the optimal use, dosing, and patient selection for RIT in these settings. Additionally, standardisation in outcome reporting and longer follow-up periods are essential for more accurate economic and clinical assessments. Overall, RIT represents a valuable therapeutic modality, yet its integration into cancer treatment regimens should be guided by further research aimed at mitigating toxicity and optimising combination strategies.

Optimizing Cancer Treatment: Exploring the Role of AI in Radioimmunotherapy

Radioimmunotherapy (RIT) is a novel cancer treatment that combines radiotherapy and immunotherapy to precisely target tumor antigens using monoclonal antibodies conjugated with radioactive isotopes. This approach offers personalized, systemic, and durable treatment, making it effective in cancers resistant to conventional therapies. Advances in artificial intelligence (AI) present opportunities to enhance RIT by improving precision, efficiency, and personalization. AI plays a critical role in patient selection, treatment planning, dosimetry, and response assessment, while also contributing to drug design and tumor classification. This review explores the integration of AI into RIT, emphasizing its potential to optimize the entire treatment process and advance personalized cancer care.

Navigating through novelties concerning mCRC treatment-the role of immunotherapy, chemotherapy, and targeted therapy in mCRC

Over the course of nearly six decades since the inception of initial trials involving 5-FU in the treatment of mCRC (metastatic colorectal cancer), our progressive comprehension of the pathophysiology, genetics, and surgical techniques related to mCRC has paved the way for the introduction of novel therapeutic modalities. These advancements not only have augmented the overall survival but have also positively impacted the quality of life (QoL) for affected individuals. Despite the remarkable progress made in the last two decades in the development of chemotherapy, immunotherapy, and target therapies, mCRC remains an incurable disease, with a 5-year survival rate of 14%. In this comprehensive review, our primary goal is to present an overview of mCRC treatment methods following the latest guidelines provided by the National Comprehensive Cancer Network (NCCN), the American Society of Clinical Oncology (ASCO), and the American Society of Colon and Rectal Surgeons (ASCRS). Emphasis has been placed on outlining treatment approaches encompassing chemotherapy, immunotherapy, targeted therapy, and surgery's role in managing mCRC. Furthermore, our review delves into prospective avenues for developing new therapies, offering a glimpse into the future of alternative pathways that hold potential for advancing the field.

Exploration of novel isoxazole-fused quinone derivatives as anti-colorectal cancer agents through inhibiting STAT3 and elevating ROS level

Colorectal cancer (CRC) is trending to be a major health problem throughout the world. Therapeutics with dual modes of action have shown latent capacity to create ideal anti-tumor activity. Signal transducer and activator of transcription 3 (STAT3) has been proved to be a potential target for the development of anti-colon cancer drug. In addition, modulation of tumor redox homeostasis through deploying exogenous reactive oxygen species (ROS)-enhancing agents has been widely applied as anti-tumor strategy. Thus, simultaneously targeting STAT3 and modulation ROS balance would offer a fresh avenue to combat CRC. In this work, we designed and synthesized a novel series of isoxazole-fused quinones, which were evaluated for their preliminary anti-proliferative activity against HCT116 cells. Among these quinones, compound 41 exerted excellent in vitro anti-tumor effect against HCT116 cell line with an IC50 value of 10.18 ± 0.4 nM. Compound 41 was proved to bind to STAT3 by using Bio-Layer Interferometry (BLI) assay, and can significantly inhibit phosphorylation of STAT3. It also elevated ROS of HCT116 cells by acting as a substrate of NQO1. Mitochondrial dysfunction, apoptosis, and cell cycle arrest, which was caused by compound 41, might be partially due to the inhibition of STAT3 phosphorylation and ROS production induced by 41. Moreover, it exhibited ideal anti-tumor activity in human colorectal cancer xenograft model and good safety profiles in vivo. Overall, this study provided a novel quinone derivative 41 with excellent anti-tumor activity by inhibiting STAT3 and elevating ROS level, and gave insights into designing novel anti-tumor therapeutics by simultaneously modulation of STAT3 and ROS.

Therapeutic efficacy of an alpha-particle emitter labeled anti-GD2 humanized antibody against osteosarcoma-a proof of concept study

PURPOSE

Current treatments for osteosarcoma (OS) have a poor prognosis, particularly for patients with metastasis and recurrence, underscoring an urgent need for new targeted therapies to improve survival. Targeted alpha-particle therapy selectively delivers cytotoxic payloads to tumors with radiolabeled molecules that recognize tumor-associated antigens. We have recently demonstrated the potential of an FDA approved, humanized anti-GD2 antibody, hu3F8, as a targeted delivery vector for radiopharmaceutical imaging of OS. The current study aims to advance this system for alpha-particle therapy of OS.

METHODS

The hu3F8 antibody was radiolabeled with actinium-225, and the safety and therapeutic efficacy of the [225Ac]Ac-DOTA-hu3F8 were evaluated in both orthotopic murine xenografts of OS and spontaneously occurring OS in canines.

RESULTS

Significant antitumor activity was proven in both cases, leading to improved overall survival. In the murine xenograft's case, tumor growth was delayed by 16-18 days compared to the untreated cohort as demonstrated by bioluminescence imaging. The results were further validated with magnetic resonance imaging at 33 days after treatment, and microcomputed tomography and planar microradiography post-mortem. Histological evaluations revealed radiation-induced renal toxicity, manifested as epithelial cell karyomegaly and suggestive polyploidy in the kidneys, suggesting rapid recovery of renal function after radiation damage. Treatment of the two canine patients delayed the progression of metastatic spread, with an overall survival time of 211 and 437 days and survival beyond documented metastasis of 111 and 84 days, respectively.

CONCLUSION

This study highlights the potential of hu3F8-based alpha-particle therapy as a promising treatment strategy for OS.

Formulation of patient dose of [177Lu]Lu-Trastuzumab using in-house developed freeze-dried kit: A path forward for clinical translation

Trastuzumab is a US-FDA-approved humanized monoclonal antibody used for the treatment of human epidermal growth factor receptor 2 (HER2)-positive breast cancer. The aim of the present work is to optimize a freeze-dried formulation of DOTA-Trastuzumab conjugate for the preparation of patient doses of [177Lu]Lu-Trastuzumab for radioimmunotherapy of breast cancer. The formulation of [177Lu]Lu-Trastuzumab usually takes a long time, and thus, such a process is not suitable for the routine preparation of this agent in hospital radiopharmacies. To circumvent this, a pre-synthesized DOTA-Trastuzumab conjugate as a freeze-dried formulation is proposed. In the present work, DOTA-Trastuzumab conjugate was subjected to a freeze-drying process after the addition of optimized amounts of radioprotectant and cryoprotectant. [177Lu]Lu-DOTA-Trastuzumab was prepared by incubating the lyophilized powder of the kit vial with medium-specific activity 177LuCl3. The final radiochemical purity of [177Lu]Lu-DOTA-Trastuzumab, prepared using freeze-dried kit, was determined to be >95%. To ascertain the reproducibility of the procedure, six consecutive batches of the freeze-dried formulation were prepared, radiolabeled, and evaluated by carrying out both in vitro and ex vivo studies. The consistency of the results of all the six consecutive batches confirmed the robustness and utility of the in-house optimized freeze-dried formulation for the preparation of patient doses of [177Lu]Lu-Trastuzumab at hospital radiopharmacies.

The application of radionuclide therapy for breast cancer

Radionuclide-mediated diagnosis and therapy have emerged as effective and low-risk approaches to treating breast cancer. Compared to traditional anatomic imaging techniques, diagnostic radionuclide-based molecular imaging systems exhibit much greater sensitivity and ability to precisely illustrate the biodistribution and metabolic processes from a functional perspective in breast cancer; this transitions diagnosis from an invasive visualization to a noninvasive visualization, potentially ensuring earlier diagnosis and on-time treatment. Radionuclide therapy is a newly developed modality for the treatment of breast cancer in which radionuclides are delivered to tumors and/or tumor-associated targets either directly or using delivery vehicles. Radionuclide therapy has been proven to be eminently effective and to exhibit low toxicity when eliminating both primary tumors and metastases and even undetected tumors. In addition, the specific interaction between the surface modules of the delivery vehicles and the targets on the surface of tumor cells enables radionuclide targeting therapy, and this represents an exceptional potential for this treatment in breast cancer. This article reviews the development of radionuclide molecular imaging techniques that are currently employed for early breast cancer diagnosis and both the progress and challenges of radionuclide therapy employed in breast cancer treatment.

Towards a structural and functional analysis of the immunoglobulin-fold proteome

The immunoglobulin fold (Ig fold) domain is a super-secondary structural motif consisting of a sandwich with two layers of β-sheets that is present in many proteins with very diverse biological functions covering a wide range of physiological processes. This domain presents a modular architecture built with β strands connected by variable length loops that has a highly conserved structural core of four β-strands and quite variable β-sheet extensions in the two sandwich layers that enable both divergent and convergent evolutionary mechanisms in the known Ig fold proteome. The central role of this Ig fold's structural plasticity in the evolutionary success of antibodies in our immune system is well established. Nature has also utilized this Ig fold in all domains of life in many different physiological contexts that go way beyond the immune system. Here we will present a structural and functional overview of the utilization of the Ig fold in different biological processes and in different cellular contexts to highlight some of the innumerable ways that this structural motif can interact in multidomain proteins to enable their diversity of functions. This includes shareable specific protein structure visualizations behind those functions that serve as starting points for further explorations of the biomolecular interactions spanning the Ig fold proteome. This overview also highlights how this Ig fold is being utilized through natural adaptation, engineering, and even building from scratch for a range of biotechnological applications.

Current Targeted Therapy for Metastatic Colorectal Cancer

Colorectal cancer (CRC) is the third most common type of cancer and the second leading cause of cancer deaths worldwide. Surgery or surgery plus radiotherapy and/or chemotherapy for patients with metastatic CRC (mCRC) were accepted as the main therapeutic strategies until the early 2000s, when targeted drugs, like cetuximab and bevacizumab, were developed. The use of targeted drugs in clinical practice has significantly increased patients' overall survival. To date, the emergence of several types of targeted drugs has opened new possibilities and revealed new prospects for mCRC treatment. Therapeutic strategies are continually being updated to select the most suitable targeted drugs based on the results of clinical trials that are currently underway. This review discusses the up-to date molecular evidence of targeted therapy for mCRC and summarizes the Food and Drug Administration-approved targeted drugs including the results of clinical trials. We also explain their mechanisms of action and how these affect the choice of a suitable targeted therapy.

Novel antigens for targeted radioimmunotherapy in hepatocellular carcinoma

Liver cancer is the sixth common cancer and forth cause of cancer-related death worldwide. Based on usually advanced stages of hepatocellular carcinoma (HCC) at the time of diagnosis, therapeutic options are limited and, in many cases, not effective, and typically result in the tumor recurrence with a poor prognosis. Radioimmunotherapy (RIT) offers a selective internal radiation therapy approach using beta or alpha emitting radionuclides conjugated with tumor-specific monoclonal antibodies (mAbs), or specific selective peptides. When compared to chemotherapy or radiotherapy, radiolabeled mAbs against cancer-associated antigens could provide a high therapeutic and exclusive radiation dose for cancerous cells while decreasing the exposure-induced side effects to healthy tissues. The recent advances in cancer immunotherapy, such as blockade of immune-checkpoint inhibitors (ICIs), has changed the landscape of cancer therapy, and the efficacy of different classes of immunotherapy has been tested in many clinical trials. Taking into account the use of ICIs in the liver tumor microenvironment, combined therapies with different approaches may enhance the outcome in the future clinical studies. With the development of novel immunotherapy treatment options in the recent years, there has been a great deal of information about combining the diverse treatment modalities to boost the effectiveness of immunomodulatory drugs. In this opinion review, we will discuss the recent advancements in RIT. The current status of immunotherapy and internal radiotherapy will be updated, and we will propose novel approaches for the combination of both techniques. Potential target antigens for radioimmunotherapy in Hepatocellular carcinoma (HCC). HCC radioimmunotherapy target antigens are the most specific and commonly accessible antigens on the surface of HCC cells. CTLA-4 ligand and receptor, TAMs, PD-1/PD-L, TIM-3, specific IEXs/TEXs, ROBO1, and cluster of differentiation antigens CD105, CD147 could all be used in HCC radioimmunotherapy. Abbreviations: TAMs, tumor-associated macrophages; CTLA-4, cytotoxic T-lymphocyte associated antigen-4; PD-1, Programmed cell death protein 1; PD-L, programmed death-ligand1; TIM-3, T-cell immunoglobulin (Ig) and mucin-domain containing protein-3; IEXs, immune cell-derived exosomes; TEXs, tumor-derived exosomes.

Chemotherapy and Physical Therapeutics Modulate Antigens on Cancer Cells

Cancer cells possess specific properties, such as multidrug resistance or unlimited proliferation potential, due to the presence of specific proteins on their cell membranes. The release of proliferation-related proteins from the membrane can evoke a loss of adaptive ability in cancer cells and thus enhance the effects of anticancer therapy. The upregulation of cancer-specific membrane antigens results in a better outcome of immunotherapy. Moreover, cytotoxic T-cells may also become more effective when stimulated ex-vivo toward the anticancer response. Therefore, the modulation of membrane proteins may serve as an interesting attempt in anticancer therapy. The presence of membrane antigens relies on various physical factors such as temperature, exposure to radiation, or drugs. Therefore, changing the tumor microenvironment conditions may lead to cancer cells becoming sensitized to subsequent therapy. This paper focuses on the therapeutic approaches modulating membrane antigens and enzymes in anticancer therapy. It aims to analyze the possible methods for modulating the antigens, such as pharmacological treatment, electric field treatment, photodynamic reaction, treatment with magnetic field or X-ray radiation. Besides, an overview of the effects of chemotherapy and immunotherapy on the immunophenotype of cancer cells is presented. Finally, the authors review the clinical trials that involved the modulation of cell immunophenotype in anticancer therapy.

Immunotherapy and Radioimmunotherapy for Desmoplastic Small Round Cell Tumor

Desmoplastic small round cell tumor (DRSCT) is a highly aggressive primitive sarcoma that primarily affects adolescent and young adult males. The 5-year survival rate is 15-30% and few curative treatment options exist. Although there is no standard treatment for DSRCT, patients are most often treated with a combination of aggressive chemotherapy, radiation, and surgery. Targeted therapy inhibitors of PDGFA and IGF-1R, which are almost uniformly overexpressed in DSRCT, have largely failed in clinical trials. As in cancer in general, interest in immunotherapy to treat DSRCT has increased in recent years. To that end, several types of immunotherapy are now being tested clinically, including monoclonal antibodies, radionuclide-conjugated antibodies, chimeric antigen receptor T cells, checkpoint inhibitors, and bispecific antibodies (BsAbs). These types of therapies may be particularly useful in DSRCT, which is frequently characterized by widespread intraperitoneal implants, which are difficult to completely remove surgically and are the frequent cause of relapse. Successful treatment with immunotherapy or radioimmunotherapy following debulking surgery could eradiate these micrometasteses and prevent relapse. Although there has been limited success to date for immunotherapy in pediatric solid tumors, the significant improvements in survival seen in the treatment of other pediatric solid tumors, such as metastatic neuroblastoma and its CNS spread, suggest a potential of immunotherapy and specifically compartmental immunotherapy in DSRCT.

Analysis of absorbed dose in radioimmunotherapy with 177Lu-trastuzumab using two different imaging scenarios: a pilot study

OBJECTIVES

Internal organ dosimetry is an important procedure to demonstrate the reliable application of 177Lu-trastuzumab radioimmunotherapy for human epidermal growth factor receptor-positive metastatic breast cancers. We are reporting the first human dosimetry study for 177Lu-trastuzumab. Another objective of our study was to calculate and compare the absorbed doses for normal organs and tumor lesions in patients before radioimmunotherapy with 177Lu-trastuzumab using two different imaging scenarios.

METHODS

Eleven patients (48.27 ± 8.95 years) with a history of metastatic breast cancer were included in the study. Postadministration of 177Lu-trastuzumab (351.09 ± 23.89 MBq/2 mg), acquisition was performed using planar and hybrid imaging scenarios at 4, 24, 72 and 168 h. Single-photon emission computed tomography/computed tomography imaging was performed at 72 h postinjection. Acquired images were processed using Dosimetry Toolkit software for the estimation of normalized cumulated activity in organs and tumor lesions. OLINDA/EXM 2.0 software was used for absorbed dose calculation in both scenarios.

RESULTS

Significant difference in normalized cumulated activity and the absorbed dose is noted between two imaging scenarios for the organs and tumor lesions (P < 0.05). Mean absorbed dose (mGy/MBq) estimated from heart, lungs, liver, spleen, kidney, adrenal, pancreas and colon using planar and hybrid scenarios were 0.81 ± 0.19 and 0.63 ± 0.17; 0.75 ± 0.13 and 0.32 ± 0.06; 1.26 ± 0.25 and 1.01 ± 0.17; 0.68 ± 0.22 and 0.53 ± 0.16; 0.91 ± 0.3 and 0.69 ± 0.24; 0.18 ± 0.04 and 0.11 ± 0.02; 0.25 ± 0.22 and 0.09 ± 0.02 and 0.75 ± 0.61 and 0.44 ± 0.28, respectively.

CONCLUSIONS

On the basis of our dosimetric evaluation, we concluded that radioimmunotherapy with 177Lu-trastuzumab is well tolerated to be implemented in routine clinical practice against HER2 positive metastatic breast cancer. Liver is the main critical organ at risk. Hybrid scenario demonstrated significantly lower absorbed doses in organs and tumors compared to the multiplanar method.

Utilization of nanotechnology in targeted radionuclide cancer therapy: monotherapy, combined therapy and radiosensitization

The rapid progress of nanomedicine field has a great influence on the different tumor therapeutic trends. It achieves a potential targeting of the therapeutic agent to the tumor site with neglectable exposure of the normal tissue. In nuclear medicine, nanocarriers have been employed for targeted delivery of therapeutic radioisotopes to the malignant tissues. This systemic radiotherapy is employed to overcome the external radiation therapy drawbacks. This review overviews studies concerned with investigation of different nanoparticles as promising carriers for targeted radiotherapy. It discusses the employment of different nanovehicles for achievement of the synergistic effect of targeted radiotherapy with other tumor therapeutic modalities such as hyperthermia and photodynamic therapy. Radiosensitization utilizing different nanosensitizer loaded nanoparticles has also been discussed briefly as one of the nanomedicine approach in radiotherapy.

Pharmacological activities and potential use of bovine colostrum for peptide-based radiopharmaceuticals: A review

Bovine colostrum (BC) is the initial milk produced by cows after giving birth. It has been used to treat human diseases, such as infections, inflammations, and cancers. Accumulating evidence suggests that bovine lactoferrin and bovine antibodies seem to be the most important bioactive constituents in BC. Thus, BC has also been reviewed for its potential to deliver short-term protection against coronavirus disease 2019 (COVID-19). In addition, it can potentially be explored as a precursor for peptide-based radiopharmaceuticals. To date, several bioactive peptides have been isolated from BC, including casocidin-1, casecidin 15 and 17, isracidin, caseicin A, B, and C. Like other peptides, bioactive peptides derived from BC could be used as a valuable precursor for radiopharmaceuticals either for diagnosis or therapy purposes. This review provides bovine colostrum’s biological activities and a perspective on the potential use of peptides from BC for developing radiopharmaceuticals in nuclear medicine.

AAZTA5-squaramide ester competing with DOTA-, DTPA- and CHX-A″-DTPA-analogues: Promising tool for 177Lu-labeling of monoclonal antibodies under mild conditions

BACKGROUND

Combining the advantages of both cyclic and acyclic chelator systems, AAZTA (1,4-bis(carboxymethyl)-6-[bis(carboxymethyl)]amino-6-methylperhydro-1,4-diazepine) is well suited for complexation of various diagnostic and therapeutic radiometals such as gallium-68, scandium-44 and lutetium-177 under mild conditions. Due to its specificity for primary amines and pH dependent binding properties, squaric acid (SA) represents an excellent tool for selective coupling of the appropriate chelator to different target vectors. Therefore, the aim of this study was to evaluate radiolabeling properties of the novel bifunctional AAZTA5-SA being coupled to a model antibody (bevacizumab) in comparison to DOTA-SA, DTPA-p-Bn-SA and CHX-A″-DTPA-p-Bn-SA using the therapeutic nuclide lutetium-177.

METHODS AND RESULTS

As proof-of-concept, bevacizumab was first functionalized with AAZTA5-SA, DOTA-SA, DTPA-p-Bn-SA or CHX-A″-DTPA-p-Bn-SA. After purification via fractionated size exclusion chromatography (SEC), the corresponding immunoconjugates were subsequently radiolabeled with lutetium-177 at pH 7 and room temperature (RT) as well as 37 °C. After 90 min, labeling of AAZTA5-SA-mAb resulted in almost quantitative radiochemical yields (RCY) of >98% and >99%, respectively. Formation of [177Lu]Lu-DTPA-p-Bn-SA-mAb indicated rapid labeling kinetics reaching similar yields at RT already after 30 min. Fast but incomplete radiolabeling of the CHX-A″-analogue could be observed with a yield of 74% after 10 min and no further significant increase. In contrast, 177Lu-labeling of DOTA-SA-mAb showed negligible radiochemical yields of <2% both at room temperature and 37 °C. In vitro complex stability measurements of [177Lu]Lu-AAZTA5-SA-mAb at 37 °C indicated >94% protein bound activity in human serum and >92% in phosphate buffered saline (PBS), respectively within 15 days. [177Lu]Lu-DTPA-p-Bn-SA-mAb and [177Lu]Lu-CHX-A″-DTPA-p-Bn-SA-mAb revealed similar to even slightly higher in vitro stability in both media.

CONCLUSION

Coupling of AAZTA5-SA to the monoclonal antibody bevacizumab allowed for 177Lu-labeling with almost quantitative radiochemical yields both at room temperature and 37 °C. Within 15 days, the resulting radioconjugate indicated very high in vitro complex stability both in human serum and PBS. Therefore, AAZTA5-SA is a promising tool for 177Lu-labeling of sensitive biomolecules such as antibodies for theranostic applications.

Perspectives on metals-based radioimmunotherapy (RIT): moving forward

Radioimmunotherapy (RIT) is FDA-approved for the clinical management of liquid malignancies, however, its use for solid malignancies remains a challenge. The putative benefit of RIT lies in selective targeting of antigens expressed on the tumor surface using monoclonal antibodies, to systemically deliver cytotoxic radionuclides. The past several decades yielded dramatic improvements in the quality, quantity, recent commercial availability of alpha-, beta- and Auger Electron-emitting therapeutic radiometals. Investigators have created new or improved existing bifunctional chelators. These bifunctional chelators bind radiometals and can be coupled to antigen-specific antibodies. In this review, we discuss approaches to develop radiometal-based RITs, including the selection of radiometals, chelators and antibody platforms (i.e. full-length, F(ab')2, Fab, minibodies, diabodies, scFv-Fc and nanobodies). We cite examples of the performance of RIT in the clinic, describe challenges to its implementation, and offer insights to address gaps toward translation.

Formulation and clinical translation of [177Lu]Lu-trastuzumab for radioimmunotheranostics of metastatic breast cancer

Trastuzumab (Herceptin®) is an approved immunotherapeutic agent used for the treatment of metastatic breast cancer over-expressing HER2 antigen receptors. The aim of the present work is to standardize the formulation protocol of [177Lu]Lu-trastuzumab addressing various reaction parameters, evaluating the efficacy of the radiolabeled product by in vitro investigations, scaling-up the preparation for administration in patients and performing preliminary clinical studies in patients suffering from metastatic breast cancer. Trastuzumab was conjugated with a suitable bi-functional chelating agent namely, p-NCS-benzyl-DOTA. On average 6.15 ± 0.92 p-NCS-benzyl-DOTA molecules were observed to be attached to each trastuzumab moiety. [177Lu]Lu-trastuzumab could be prepared with >95% radiochemical purity (% RCP) employing the optimized radiolabeling procedure. In vitro studies revealed the affinity of [177Lu]Lu-trastuzumab towards HER2 +ve cancer cell lines as well as against HER2 protein (K d = 13.61 nM and 11.36 nM, respectively). The value for percentage immunoreactive fraction (% IRF) for [177Lu]Lu-trastuzumab was observed to be 76.92 ± 2.80. Bio-distribution studies in Swiss mice revealed non-specific uptake in the blood, liver, lungs and heart followed by gradual clearance of activity predominantly through the hepatobiliary route. Preliminary clinical studies carried out in 8 cancer patients with immunohistochemically proven HER2 positive metastatic breast cancer revealed preferential localization of [177Lu]Lu-trastuzumab in breast cancer lesions, which was in concordance with [18F]FDG-PET scans recorded earlier in the same patient indicating the potential of the agent towards radioimmunotheranostic applications.

Establishment of a novel anti-TROP2 monoclonal antibody TrMab-29 for immunohistochemical analysis

TROP2 is a type I transmembrane glycoprotein originally identified in human trophoblast cells that is overexpressed in several types of cancer. To better understand the role of TROP2 in cancer, we herein aimed to develop a sensitive and specific anti-TROP2 monoclonal antibody (mAb) for use in flow cytometry, Western blot, and immunohistochemistry using a Cell-Based Immunization and Screening (CBIS) method. Two mice were immunized with N-terminal PA-tagged and C-terminal RAP/MAP-tagged TROP2-overexpressed Chinese hamster ovary (CHO)-K1 cells (CHO/PA-TROP2-RAP-MAP), and hybridomas showing strong signals from PA-tagged TROP2-overexpressed CHO-K1 cells (CHO/TROP2-PA) and weak-to-no signals from CHO-K1 cells were selected using flow cytometry. We demonstrated using flow cytometry that the established anti-TROP2 mAb, TrMab-29 (mouse IgG₁ kappa), detected TROP2 in MCF7 breast cancer cell line as well as CHO/TROP2-PA cells. Western blot analysis showed a 40 kDa band in lysates prepared from both CHO/TROP2-PA and MCF7 cells. Furthermore, TROP2 was strongly detected by immunohistochemical analysis using TrMab-29, indicating that TrMab-29 may be a valuable tool for the detection of TROP2 in cancer.

The Impact of Tissue Type and Density on Dose Point Kernels for Patient-Specific Voxel-Wise Dosimetry: A Monte Carlo Investigation

We report the generation of dose point kernels for clinically-relevant radionuclide beta decays and monoenergetic electrons in various tissues to understand the impact of tissue type on dose point kernels. Currently available voxel-wise dosimetry approaches using dose point kernels ignore tissue composition and density heterogeneities. Therefore, the study on the impact of tissue type on dose point kernels is warranted. Simulations were performed using the GATE Monte Carlo toolkit, which encapsulates GEANT4 libraries. Dose point kernels were simulated in phantoms of water, compact bone, lung, adipose tissue, blood and red marrow for radionuclides 90Y, 188Re, 32P, 89Sr, 186Re, 153Sm and 177Lu and monoenergetic electrons (0.015-10 MeV). All simulations were performed by assuming an isotropic point source of electrons at the center of a homogeneous spherical phantom. Tissue-specific differences between kernels were investigated by normalizing kernels for effective pathlength. Transport of 20 million particles was found to provide sufficient statistical precision in all simulated kernels. The simulated dose point kernels demonstrate excellent agreement with other Monte Carlo packages. Deviation from kernels reported in the literature did not exceed a 10% global difference, which is consistent with the variability among published results. There are no significant differences between the dose point kernel in water and kernels in other tissues that have been scaled to account for density; however, tissue density predictably demonstrated itself to be a significant variable in dose point kernel distribution.

Development of an Antigen Detection ELISA for Bancroftian Filariasis Using BmSXP-Specific Recombinant Monoclonal Antibody

Lymphatic filariasis is a mosquito-borne parasitic disease responsible for morbidity and disability that affects 1.2 billion people worldwide, mainly the poor communities. Currently, filarial antigen testing is the method of choice for the detection of bancroftian filariasis, and to date, there are two commonly used tests. In the present study, a recently reported recombinant monoclonal antibody (5B) specific to BmSXP filarial antigen was used in developing an ELISA for the detection of circulating filarial antigen in sera of patients with bancroftian filariasis. The performance of the ELISA was evaluated using 124 serum samples. The ELISA was positive with all sera from microfilaremic bancroftian filariasis patients (n = 34). It also showed 100% diagnostic specificity when tested with sera from 50 healthy individuals and 40 patients with other parasitic diseases. The developed assay using the novel 5B recombinant monoclonal antibody could potentially be a promising alternative antigen detection test for bancroftian filariasis.

Improving 131I Radioiodine Therapy By Hybrid Polymer-Grafted Gold Nanoparticles

BACKGROUND

Human trials combining external radiotherapy (RT) and metallic nanoparticles are currently underway in cancer patients. For internal RT, in which a radioisotope such as radioiodine is systemically administered into patients, there is also a need for enhancing treatment efficacy, decreasing radiation-induced side effects and overcoming radio-resistance. However, if strategies vectorising radioiodine through nanocarriers have been documented, sensitizing the neoplasm through the use of nanotherapeutics easily translatable to the clinic in combination with the standard systemic radioiodine treatment has not been assessed yet.

METHOD AND MATERIALS

The present study explored the potential of hybrid poly(methacrylic acid)-grafted gold nanoparticles to improve the performances of systemic 131I-mediated RT on cancer cells and in tumor-bearing mice. Such nanoparticles were chosen based on their ability previously described by our group to safely withstand irradiation doses while exhibiting good biocompatibility and enhanced cellular uptake.

RESULTS

In vitro clonogenic assays performed on melanoma and colorectal cancer cells showed that poly(methacrylic acid)-grafted gold nanoparticles (PMAA-AuNPs) could efficiently lead to a marked tumor cell mortality when combined to a low activity of radioiodine, which alone appeared to be essentially ineffective on tumor cells. In vivo, tumor enrichment with PMAA-AuNPs significantly enhanced the killing potential of a systemic radioiodine treatment.

CONCLUSION

This is the first report of a simple and reliable nanomedicine-based approach to reduce the dose of radioiodine required to reach curability. In addition, these results open up novel perspectives for using high-Z metallic NPs in additional molecular radiation therapy demonstrating heterogeneous dose distributions.

Passive-specific immunotherapy with monoclonal antibodies for prostate cancer: A systematic review

INTRODUCTION

Treatment of metastatic castration-resistant prostate cancer with conventional therapies is still not successful. Therefore, application of novel biological approaches such as immunotherapy, which appears to be more effective and less toxic, is necessary. Monoclonal antibodies against cancer specific antigens are a kind of immunotherapy that have been approved for specific types of cancer and are being investigated for prostate cancer as well. The aim of this review was to assess the effectiveness and safety of monoclonal antibodies for treatment of advanced prostate cancer.

METHOD

According to the search strategy stated in our systematic review protocol, Scopus, Medline, TRIP, CENTRAL, ProQuest, DART and OpenGrey databases were searched. Data collection and quality assessment were done independently by two authors and any disagreements between the collected data were resolved by a third author. A meta-analysis was not feasible as there was a considerable statistical heterogeneity among the trials. Hence, this review was limited to a narrative analysis of the included studies.

RESULTS

We found 9756 references by applying search strategy in 4 databases of journal articles and 3 databases of grey literature. We then discarded 3957 duplicate citations using Endnote software and 5143 articles due to obvious irrelevancy of their topics in primary screening. In secondary screening of 656 fulltexts, we excluded 538 articles, and finally included 12 trials in this systematic review, updated on 23 June 2017. The overall quality of the studies was fair. In general, results of this systematic review show promising advances in the treatment of prostate cancer patients with monoclonal antibodies against prostate-specific antigens with regard to PSA/disease response. Some of the studies reported pain relief after treatment as well.

CONCLUSION

Currently, the role of immunotherapy in the treatment of advanced prostate cancer still remains debated. Although passive specific immunotherapy could be offered as a novel therapeutic option in the coming years, patients should be informed about the risks and benefits of this therapy. One of the obstacles in this review was the lack of adequate assessment of survival-related endpoints reported in the included studies. Our study provides support for further research in this field.

Novel Methods to Improve the Efficiency of Radioimmunotherapy for Non-Hodgkin Lymphoma

Radioimmunotherapy (RIT) is a novel strategy for treating non-Hodgkin lymphoma (NHL). Several studies have shown the promising results of using RIT in NHL, which have led to FDA approval for two RIT agents in treating low grade NHL. In spite of these favorable results in low-grade NHL, most of the aggressive or relapsed/refractory NHL subjects experience relapses following RIT. Although more aggressive treatments such as myeloablative doses of RIT followed by stem cell transplantation appear to be able to provide a longer survival for some patients these approaches are associated with significant treatment-related adverse events and challenging to deliver in most centers. Therefore, it seems reasonable to develop treatment approaches that enhance the efficiency of RIT, while reducing its toxicity. In this paper, novel methods that improve the efficiency of RIT and reduce its toxicity through various mechanisms are reviewed. Further clinical development of these methods could expand the NHL patient groups eligible for receiving RIT, and even extend the use of RIT to new indications and disease groups in future.

Therapeutic efficacy evaluation of radioimmunotherapy with 90 Y-labeled anti-podoplanin antibody NZ-12 for mesothelioma

Podoplanin is a type I transmembrane sialomucin‐like glycoprotein that is highly expressed in malignant mesothelioma. The rat‐human chimeric antibody NZ‐12 has high affinity for human podoplanin and antibody‐dependent cellular cytotoxicity and is applicable for radioimmunotherapy (RIT) to enhance the antitumor effect. In the present study, we evaluated the in vivo and in vitro properties of radiolabeled NZ‐12 and the antitumor effect of RIT with ⁹⁰Y‐labeled NZ‐12 in an NCI‐H226 (H226) malignant mesothelioma xenograft mouse model. ¹¹¹In‐labeled NZ‐12 bound specifically to H226 cells with high affinity, and accumulation was high in H226 tumors but low in major organs. RIT with ⁹⁰Y‐labeled NZ‐12 significantly suppressed tumor growth and prolonged survival without body weight loss and obvious adverse effects. Higher podoplanin expression levels were observed in human mesothelioma specimens, suggesting higher tumor accumulation of ⁹⁰Y‐labeled NZ‐12 in patients compared with the H226 tumor xenografts. Our findings suggest that ⁹⁰Y‐labeled NZ‐12 is a promising RIT agent as a new therapeutic option for malignant mesothelioma that warrants further clinical studies to evaluate the dosimetry and efficacy in patients.

New physical approaches to treat cancer stem cells: a review

Cancer stem cells (CSCs) have been identified as the main center of tumor therapeutic resistance. They are highly resistant against current cancer therapy approaches particularly radiation therapy (RT). Recently, a wide spectrum of physical methods has been proposed to treat CSCs, including high energetic particles, hyperthermia (HT), nanoparticles (NPs) and combination of these approaches. In this review article, the importance and benefits of the physical CSCs therapy methods such as nanomaterial-based heat treatments and particle therapy will be highlighted.

Combined treatment of pancreatic cancer xenograft with 90Y-ITGA6B4-mediated radioimmunotherapy and PI3K/mTOR inhibitor

AIM

To investigate the therapeutic effect of combined integrin α6β4-targeted radioimmunotherapy (RIT) and PI3K/mTOR inhibitor BEZ235 in a pancreatic cancer model.

METHODS

Phosphorylation of Akt, mTOR, the downstream effectors eukaryotic initiation factor 4E binding protein 1 (4EBP1) and S6 ribosomal protein (S6) were evaluated in BxPC-3 human pancreatic cancer cells treated with Yttrium-90 (90Y) labeled anti-integrin α6β4 antibody (ITGA6B4) and BEZ235 by western blotting. The cytotoxic effect of BEZ235 was investigated using a colony formation assay. Therapeutic efficacy enhancement by oral BEZ235 administration was assessed using mice bearing BxPC-3 xenograft tumors. Tumor volume measurements and immunohistochemical analyses (cell proliferation marker Ki-67, DNA damage marker p-H2AX and p-4EBP1 staining) of tumors were performed for evaluation of combined treatment with 90Y-ITGA6B4 plus BEZ235, or each arm alone.

RESULTS

We found that phosphorylation of Akt (p-Akt), 4EBP1 (p-4EBP1) and S6 (p-S6) was inhibited by BEZ235. Colony formation in BxPC-3 cells was additively suppressed by the combination of 90Y-ITGA6B4 and BEZ235. Pretreatment with BEZ235 before 90Y-ITGA6B4 exposure resulted in significant reduction of cells plating efficiency (PE) (0.54 ± 0.11 vs 2.81 ± 0.14 with 185 kBq/mL 90Y-ITGA6B4 exposure, P < 0.01; 0.39 ± 0.08 vs 1.88 ± 0.09 with 370 kBq/mL 90Y-ITGA6B4 exposure, P < 0.01) when 5 × 103 cells per dish were plated. In vivo, the combined treatment with 90Y-ITGA6B4 plus BEZ235 enhanced the inhibition of tumor growth and statistically significant differences of relative tumor volume were observed for 27 d after the treatment start date when compared with the 90Y-ITGA6B4 single injection treatment (1.03 ± 0.38 vs 1.5 ± 0.15 at Day 27, P < 0.05), and for 41 d when compared with the BEZ235 treatment alone (1.8 ± 0.7 vs 3.14 ± 1.19 at Day 41, P < 0.05). Tumors from treatment groups showed reduction in volumes, decreased Ki-67-positive cells, increased p-H2AX-positive cells and decreased p-4EBP1 expression.

CONCLUSION

The therapeutic efficacy of 90Y-ITGA6B4-RIT can be improved by combining with dual PI3K and mTOR inhibitor, BEZ235, in a pancreatic cancer model suggesting potential clinical application.

Discrepancy Between Tumor Antigen Distribution and Radiolabeled Antibody Binding in a Nude Mouse Xenograft Model of Human Melanoma

OBJECTIVES

Biodistribution of antibodies is vital to successful immunoscintigraphy/immunotherapy, and it is assumed to be similar to antigen distribution. We measured and compared the binding pattern of radiolabeled antibody to tissue antigen distribution in a nude mouse xenograft model of human melanoma.

METHODS

We transplanted 10⁷ FEM-XII human melanoma cells into the right flank of five nude mice. For the control, we transplanted 5 × 10⁶ LS174T human colon cancer cells into the left flank. Two weeks later, 10 μCi of ¹³¹I-labeled melanoma-associated 96.5 monoclonal antibody (targeting p97 antigen) was intravenously injected. Three days later, we sacrificed the mice and evaluated 96.5 antibody binding and concentration in the tumors by ex vivo quantitative autoradiography (QAR). Two months later, we incubated adjacent tumor tissue slices in various concentrations of ¹²⁵I-labeled 96.5 MoAb and evaluated the distribution/concentration of p97 antigen by in vitro QAR.

RESULTS

p97 antigen distribution was homogeneous in the tumors (total antigen concentration [Bmax] = 17.36-38.36 pmol/g). In contrast, radiolabeled 96.5 antibody binding was heterogenous between location within the tumor (estimated bound antigen concentration = 0.7-6.6 pmol/g). No quantifiable parameters were found to be related with radiolabeled antibody binding and tumor antigen distribution. Antibody-bound tumor antigen to total antigen ratios ranged between 2% and 38%.

CONCLUSIONS

Heterogeneous features of target antibody binding were observed in contrast to relatively homogenous feature of tumor antigen. We did not identify any correlations between p97 antigen distribution and 96.5 antibody binding in melanoma tissue. Radiolabeled 96.5 antibody binding patterns within melanoma cannot be predicted based on p97 antigen distribution in the tumor, which needs to be further studied with several other methods and more subjects in the future.

Re-188 Enhances the Inhibitory Effect of Bevacizumab in Non-Small-Cell Lung Cancer

The malignant behaviors of solid tumors such as growth, infiltration and metastasis are mainly nourished by tumor neovascularization. Thus, anti-angiogenic therapy is key to controlling tumor progression. Bevacizumab, a humanized anti-vascular endothelial growth factor (VEGF) antibody, plus chemotherapy or biological therapy can prolong survival for cancer patients, but treatment-related mortality is a concern. To improve inhibitory effect and decrease side-effects on non-small-cell lung cancer (NSCLC), we used Re-188, which is a β emitting radionuclide, directly labeled with bevacizumab for radioimmunotherapy in a human A549 tumor model. Cytotoxic assay data showed that, after ¹⁸⁸ReO₄^- or ¹⁸⁸Re-bevacizumab at different concentration for 4 and 24 h, a time- and radioactivity does-dependent reduction in cell viability occurred. Also, an apoptosis assay conformed great apoptosis in the ¹⁸⁸Re-bevacizumab group compared with controls and other treatment groups. In vivo, tumor volumes in the ¹⁸⁸Re-bevacizumab (11.1 MBq/mice) group were not reduced but growth was delayed compared with other groups. Thus, ¹⁸⁸Re-bevacizumab enhanced the therapeutic effect of bevacizumab, suggesting a potential therapeutic strategy for NSCLC treatment.

MABS: targeted therapy tailored to the patient's need

Monoclonal antibodies (MABs) represent the window of opportunity in modern medicine. As immunology plays a vital role both in our survival and in disease development, MABs were found to be of great help in diagnosing, prognosticating and managing certain malignancies, inflammatory conditions, autoimmune as well as infectious diseases. Technological advances have enabled the production of MABs that target specific antigens linked with several disease processes. These drugs are now a component of therapy, not only for many common malignancies, including breast, colorectal, lung and pancreatic cancers, as well as lymphoma, leukaemia and multiple myeloma, but also for several inflammatory conditions such as rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis and inflammatory bowel disease. Targeted therapy has raised new questions about tailoring treatment, including cancer management, to the individual patient's needs. This would have a positive impact on the drug's effectiveness and toxicity as well as the economics of care. While targeted MABs are generally better tolerated than traditional chemotherapy, they are associated with several adverse effects, which vary from one patient to another.