Long-Term Toxicity of 213Bi-Labelled BSA in Mice

Bioactive Bismuth Compounds: Is Their Toxicity a Barrier to Therapeutic Use?

Bismuth compounds are considered relatively non-toxic, with their low solubility in aqueous solutions (e.g., biological fluids) being the major contributing factor to this property. Bismuth derivatives are widely used for the treatment of peptic ulcers, functional dyspepsia, and chronic gastritis. Moreover, the properties of bismuth compounds have also been extensively explored in two main fields of action: antimicrobial and anticancer. Despite the clinical interest of bismuth-based drugs, several side effects have also been reported. In fact, excessive acute ingestion of bismuth, or abuse for an extended period of time, can lead to toxicity. However, evidence has demonstrated that the discontinuation of these compounds usually reverses their toxic effects. Notwithstanding, the continuously growing use of bismuth products suggests that it is indeed part of our environment and our daily lives, which urges a more in-depth review and investigation into its possible undesired activities. Therefore, this review aims to update the pharmaco-toxicological properties of bismuth compounds. A special focus will be given to in vitro, in vivo, and clinical studies exploring their toxicity.

Bismuth-213 for Targeted Radionuclide Therapy: From Atom to Bedside

In contrast to external high energy photon or proton therapy, targeted radionuclide therapy (TRNT) is a systemic cancer treatment allowing targeted irradiation of a primary tumor and all its metastases, resulting in less collateral damage to normal tissues. The α-emitting radionuclide bismuth-213 (213Bi) has interesting properties and can be considered as a magic bullet for TRNT. The benefits and drawbacks of targeted alpha therapy with 213Bi are discussed in this review, covering the entire chain from radionuclide production to bedside. First, the radionuclide properties and production of 225Ac and its daughter 213Bi are discussed, followed by the fundamental chemical properties of bismuth. Next, an overview of available acyclic and macrocyclic bifunctional chelators for bismuth and general considerations for designing a 213Bi-radiopharmaceutical are provided. Finally, we provide an overview of preclinical and clinical studies involving 213Bi-radiopharmaceuticals, as well as the future perspectives of this promising cancer treatment option.

Tannins extract from Galla Chinensis can protect mice from infection by Enterotoxigenic Escherichia coli O101

Background

Enterotoxigenic Escherichia coli (ETEC) is classically associated with acute secretory diarrhea, which induces 2 million people death in developing countries over a year, predominantly children in the first years of life. Previously, tannins (47.75%) were extracted from Galla Chinensis and prepared as Galla Chinensis oral solution (GOS) which showed significant antidiarrheal activity in a castor oil-induced diarrhea in mice. Whether the tannins extract were also effective in treatment of ETEC-induced diarrhea was determined in this study.

Methods

Mice were randomly divided into 6 groups (n = 22). The mice in the normal and untreated groups were given normal saline. Three GOS-treated groups were received different concentrations of GOS (5, 10 and 15%, respectively) at a dose of 10 mL/kg. Mice in the positive control group were fed with loperamide (10 mg/kg). The treatment with GOS started 3 days before infection with ETEC and continued for 4 consecutive days after infection. On day 3, mice were all infected with one dose of LD₅₀ of ETEC, except those in the normal group. Survival of mice was observed daily and recorded throughout the study. On days 4 and 7, samples were collected from 6 mice in each group.

Results

GOS could increase the survival rate up to 75%, while in the untreated group it is 43.75%. The body weights of mice treated with 15% GOS were significantly increased on day 7 in comparison with the untreated group and the normal group. GOS-treatment recovered the small intestine coefficient enhanced by ETEC-infection. The diarrhea index of mice treated with GOS was significantly decreased. GOS increased the levels of IgG and sIgA in the terminal ileum and decreased the levels of pro-inflammatory cytokines (IFN-γ, TNF-α, IL-1β, IL-6 and IL-8) in serum. GOS could increase the amount of intestinal probiotics, Lactobacilli and Bifidobacteria. GOS could alleviate colon lesions induced by ETEC-infection. GOS showed higher potency than loperamide.

Conclusions

GOS could be a promising drug candidate for treating ETEC infections.

Targeted-Alpha-Therapy Combining Astatine-211 and anti-CD138 Antibody in A Preclinical Syngeneic Mouse Model of Multiple Myeloma Minimal Residual Disease

Simple Summary

Multiple myeloma is a cancer that remains incurable. Among the many therapies under evaluation, antibodies can be used as vehicles to target and deliver toxic radiation to the tumour cells. Our objective was therefore to investigate the potential of targeted alpha therapy, combining an anti-CD138 mAb with astatine-211, to destroy the residual cells responsible for relapse. We have shown in a mouse model that mimics human disease, that destroying multiple myeloma cells is feasible with low toxicity by injecting an anti-CD138 mAb coupled with astatine-211. This approach could eradicate residual cells after initial treatment and thus prevent recurrence.

Abstract

Despite therapeutic progress in recent years with the introduction of targeted therapies (daratumumab, elotuzumab), multiple myeloma remains an incurable cancer. The question is therefore to investigate the potential of targeted alpha therapy, combining an anti-CD138 antibody with astatine-211, to destroy the residual cells that cause relapses. A preclinical syngeneic mouse model, consisting of IV injection of 1 million of 5T33 cells in a KaLwRij C57/BL6 mouse, was treated 10 days later with an anti-mCD138 antibody, called 9E7.4, radiolabeled with astatine-211. Four activities of the ²¹¹At-9E7.4 radioimmunoconjugate were tested in two independent experiments: 370 kBq (n = 16), 555 kBq (n = 10), 740 kBq (n = 17) and 1100 kBq (n = 6). An isotype control was also tested at 555 kBq (n = 10). Biodistribution, survival rate, hematological parameters, enzymatic hepatic toxicity, histological examination and organ dosimetry were considered. The survival median of untreated mice was 45 days after engraftment. While the activity of 1100 kBq was highly toxic, the activity of 740 kBq offered the best efficacy with 65% of overall survival 150 days after the treatment with no evident sign of toxicity. This work demonstrates the pertinence of treating minimal residual disease of multiple myeloma with an anti-CD138 antibody coupled to astatine-211.

Preclinical Evaluation of Radiation-Induced Toxicity in Targeted Alpha Therapy Using [211At] NaAt in Mice: A Revisit

We recently reported the dose-dependent therapeutic effect of ²¹¹At-NaAt in differentiated thyroid cancer xenograft models. In the present study, we evaluated the radiation-induced toxicity of ²¹¹At-NaAt using detailed hematological, biochemical, and histological analyses. Biodistribution of ²¹¹At-NaAt was measured in normal ICR mice (n = 12), absorbed doses in the major organs were calculated. Groups of ICR mice (n = 60) were injected with 0.1 MBq or 1 MBq of ²¹¹At-NaAt, using saline as the control group (n = 30). Body weight and food intake were followed up for 60 days. Blood cell counts and serum level of biochemical parameters were measured 3, 7, 15, 29, 60 days after injection. Histological analyses of the major organs with hematoxylin and eosin staining were performed. Biodistribution study revealed a high-absorbed dose in the thyroid gland, stomach, bladder, heart, lungs, spleen, kidneys, and testis. The 0.1 MBq group showed no abnormalities. The 1 MBq group showed decreased body weight and food intake. Histological analysis showed atrophy and fibrosis in the thyroid gland, a transient hypospermatogenesis in the testis on day 29 was found in one mouse. Hematological toxicity was mild and transient. The total cholesterol, albumin, and total protein increased with no signs of recovery, which was considered to be caused by hypothyroidism. High-dose administration of ²¹¹At-NaAt showed transient toxicity in the white blood cells and testis without severe hematological or renal toxicity, suggesting its tolerable safety as targeted alpha-therapy for differentiated thyroid cancer in the 1 MBq group.

Alpha-Emitters and Targeted Alpha Therapy in Oncology: from Basic Science to Clinical Investigations

Alpha-emitters are radionuclides that decay through the emission of high linear energy transfer α-particles and possess favorable pharmacologic profiles for cancer treatment. When coupled with monoclonal antibodies, peptides, small molecules, or nanoparticles, the excellent cytotoxic capability of α-particle emissions has generated a strong interest in exploring targeted α-therapy in the pre-clinical setting and more recently in clinical trials in oncology. Multiple obstacles have been overcome by researchers and clinicians to accelerate the development of targeted α-therapies, especially with the recent improvement in isotope production and purification, but also with the development of innovative strategies for optimized targeting. Numerous studies have demonstrated the in vitro and in vivo efficacy of the targeted α-therapy. Radium-223 (²²³Ra) dichloride (Xofigo®) is the first α-emitter to have received FDA approval for the treatment of prostate cancer with metastatic bone lesions. There is a significant increase in the number of clinical trials in oncology using several radionuclides such as Actinium-225 (²²⁵Ac), Bismuth-213 (²¹³Bi), Lead-212 (²¹²Pb), Astatine (²¹¹At) or Radium-223 (²²³Ra) assessing their safety and preliminary activity. This review will cover their therapeutic application as well as summarize the investigations that provide the foundation for further clinical development.

miR-124/MCP-1 signaling pathway modulates the protective effect of itraconazole on acute kidney injury in a mouse model of disseminated candidiasis

Previous studies have indicated that monocyte chemoattractant protein-1 (MCP‑1), also referred to as C‑C motif chemokine ligand 2, has a significant role in the pathogenesis of sepsis, however, how microRNAs (miRs) contribute to this process remains to be fully elucidated. In the present study, using a mouse model of disseminated candidiasis, the renoprotective effect of itraconazole (ITR) and adenovirus‑delivered miR‑124 was investigated. The mice were treated with ITR (50 mg/kg) or transfected with miR‑124 mimics via tail‑vein injection 7 days prior to Candida albicans infection. The survival outcome was monitored following candidiasis‑induced sepsis with ITR or miR‑124 mimics treatment. The levels of pro‑inflammatory cytokines, including tumor necrosis factor‑α (TNF‑α), interleukin‑1β (IL‑1β) and IL‑6, were determined using enzyme‑linked immunosorbent assays. The mRNA and protein levels were assayed using reverse transcription-quantitative polymerase chain reaction and western blot analyses, respectively. The results showed that ITR and miR‑124 mimics improved the survival outcome in candidiasis‑induced septic mice. The findings also indicated a significant downregulation in the serum levels of TNF‑α, IL‑1β and IL‑6 in the septic mice treated with ITR or miR‑124 mimics. Of note, ITR treatment significantly increased the expression of miR‑124 and decreased the levels of MCP‑1 in the kidneys of the septic mice. It was also shown that the overexpression of miR‑124 reduced the expression of MCP‑1 and attenuated candidiasis‑induced acute kidney injury (AKI) in septic mice. Transfection with miR‑124 mimics was equivalent to ITR in reducing the excessive inflammatory response and renal lesions in septic mice. These results provided evidence supporting the use of miR‑124 mimics as a therapeutic approach for attenuating candidiasis-induced AKI.

Preparation of Galla Chinensis Oral Solution as well as Its Stability, Safety, and Antidiarrheal Activity Evaluation

BACKGROUND OF THE STUDY

As a widely used traditional medicine, Galla Chinensis is rich in tannins. However, there are few detailed studies about pharmaceutical preparations of Galla Chinensis tannin extract (GTE). In the present experiments, for better application and to investigate the possibility that Galla Chinensis tannin extract can be used as an antidiarrheal drug, we prepared Galla Chinensis oral solution (GOS).

MATERIALS AND METHODS

GOS was prepared with GTE, and its physicochemical and microbiological stability was evaluated. The oral acute toxicity of GOS was calculated by the 50% lethal dose (LD₅₀). The antidiarrheal activity was determined in a castor oil-induced diarrhea model in mice through diarrhea symptoms, fluid accumulation ratio, and percentage of distance moved by charcoal meal.

RESULTS

The tannin content of GTE was 47.75%. GOS could endure a high temperature without a significant decrease of tannin content. After storage for six months, the tannin content of GOS was still more than 90%. GOS was determined to be nontoxic. Meanwhile, GOS showed significant antidiarrheal activity in a castor oil-induced diarrhea model in mice (P < 0.01).

CONCLUSION

The results suggested that GOS is an effective and stable antidiarrheal drug that can be used to complement other therapies.

Biodistribution and evaluation of 131 I-labeled neuropilin-binding peptide for targeted tumor imaging

Neuropilin-1 (NRP-1) is overexpressed in several kinds of cancer cell and contributes to tumor aggressiveness. Recently, the arginine/lysine-rich peptide with C-terminal motifs (R/K)XX(R/K) indicated promising penetrating and transporting capability into NRP-1 positive cancer cells. In the present study, we describe a ¹³¹ I-labeled C-end rule motif peptide conjugate, Tyr-tLyp-1, for NRP-1 positive tumor targeting and imaging properties. Briefly, a truncated Lyp-1 peptide was designed to expose its C-end motif and conjugated to tyrosine for radiolabeling after structural modification. The peptide indicated specific binding to A549 cancer cells at 2 μM concentration, and its binding was dependent on NRP-1 expression and could be inhibited by other NRP-1-binding peptides. In vivo imaging of ¹³¹ I-labeled Tyr-tLyp-1peptide showed that a subcutaneous A549 xenograft tumor could be visualized using a SPECT/CT scanner. The tumor uptake of ¹³¹ I-Tyr-tLyp-1 was 4.77 times higher than the uptake in muscles by SPECT/CT software quantification at 6 h post injection. Together, this study indicated that truncated Lyp-1 peptide could specifically localize in NRP-1 positive tumors and successfully mediate the ¹³¹ I radionuclide diagnosis, indicating promising targeted imaging capability for NRP-1 positive tumors. Copyright © 2016 John Wiley & Sons, Ltd.