Radium-223 in combination with paclitaxel in cancer patients with bone metastases: safety results from an open-label, multicenter phase Ib study

Bone Metastases

ABSTRACT

Bone metastases occur frequently in common malignancies such as breast and prostate cancer. They are responsible for considerable morbidity and skeletal-related events. Fortunately, there are now several systemic, focal, and targeted therapies that can improve quality and length of life, including radionuclide therapies. It is therefore important that bone metastases can be detected as early as possible and that treatment can be accurately and sensitively monitored. Several bone-specific and tumor-specific single-photon emission computed tomography and positron emission tomography molecular imaging agents are available, for detection and monitoring response to systemic therapeutics, as well as theranostic agents to confirm target expression and predict response to radionuclide therapies.

Alpha-Emitter Radium-223 Induces STING-Dependent Pyroptosis to Trigger Robust Antitumor Immunity

Radium-223 (223 Ra) is the first-in-class alpha-emitter to mediate tumor eradication, which is commonly thought to kill tumor cells by directly cleaving double-strand DNA. However, the immunogenic characteristics and cell death modalities triggered by 223 Ra remain unclear. Here, it is reported that the 223 Ra irradiation induces the pro-inflammatory damage-associated molecular patterns including calreticulin, HMGB1, and HSP70, hallmarks of tumor immunogenicity. Moreover, therapeutic 223 Ra retards tumor progression by triggering pyroptosis, an immunogenic cell death. Mechanically, 223 Ra-induced DNA damage leads to the activation of stimulator of interferon genes (STING)-mediated DNA sensing pathway, which is critical for NLRP3 inflammasome-dependent pyroptosis and subsequent DCs maturation as well as T cell activation. These findings establish an essential role of STING in mediating alpha-emitter 223 Ra-induced antitumor immunity, which provides the basis for the development of novel cancer therapeutic strategies and combinatory therapy.

Gold Nanoparticles as Exquisite Colorimetric Transducers for Water Pollutant Detection

Gold nanoparticles (AuNPs) are useful nanomaterials as transducers for colorimetric sensors because of their high extinction coefficient and ability to change color depending on aggregation status. Therefore, over the past few decades, AuNP-based colorimetric sensors have been widely applied in several environmental and biological applications, including the detection of water pollutants. According to various studies, water pollutants are classified into heavy metals or cationic metal ions, toxins, and pesticides. Notably, many researchers have been interested in AuNP that detect water pollutants with high sensitivity and selectivity, while offering no adverse environmental issues in terms of AuNP use. This review provides a representative overview of AuNP-based colorimetric sensors for detecting several water pollutants. In particular, we emphasize the advantages of AuNP as colorimetric transducers for water pollutant detection in terms of their low toxicity, high stability, facile processability, and unique optical properties. Next, we discuss the status quo and future prospects of AuNP-based colorimetric sensors for the detection of water pollutants. We believe that this review will promote research and development of AuNP as next-generation colorimetric transducers for water pollutant detection.

A phase IB and randomised phase IIA trial of CApecitabine plus Radium-223 (Xofigo™) in breast cancer patients with BONe metastases: CARBON trial results

Background

Approximately 70% of patients with metastatic breast cancer (MBC) develop bone metastases. Despite advances in systemic treatment options and the use of bone targeted agents in the management of bone metastases to reduce skeletal morbidity, there remains an unmet need for further treatment options. Radium-223 (Ra223) is an alpha-emitting radiopharmaceutical that is preferentially taken up into bone at sites of increased osteoblastic activity where it emits high-energy, short-range alpha-particles that could provide a targeted anti-tumour effect on bone metastases. Here we evaluate the safety, feasibility and efficacy findings of the combination of Ra223 with capecitabine chemotherapy in patients with MBC with bone involvement.

Methods

CARBON is a multi-centre, open-label phase IB/IIA study evaluating the combination of Ra223 (55 kBq/kg day 1 given on 6 weekly schedule) and capecitabine (1000 mg/m2 bd days 4-17 every 21 days) in patients with bone metastases from MBC (± other disease sites). Other eligibility criteria included ECOG performance status 0-2, ≤2 lines of chemotherapy for MBC and current bisphosphonate or denosumab use for ≥ 6 weeks. The phase IB part of the trial (6 patients) was conducted to provide preliminary feasibility and safety of capecitabine + Ra223. Thereafter, 28 patients were randomised (2:1) to capecitabine + Ra223 or capecitabine alone to further characterise the safety profile and evaluate efficacy, the primary efficacy endpoint being the bone turnover marker (urinary n-telopeptide of type I collagen) change from baseline to end of cycle 5 and secondary endpoints of time to first symptomatic skeletal event, and disease progression at extra-skeletal and bone disease.

Results

In addition to bone metastases, 10/23 [44%] and 13/23 [57%] capecitabine + Ra223 and 2/11 [18%] and 9/11 [82%] capecitabine alone patients had soft tissue and visceral disease sites respectively. More capecitabine + Ra223 patients had received prior chemotherapy for MBC: 11/23 [48%] vs 2/11 [18%]. The analysis populations comprise 34 patients (23 capecitabine + Ra223, 11 capecitabine); 2 patients randomised to capecitabine + Ra223 received capecitabine alone and are included in the capecitabine arm. Median number of cycles received was 8.5 in capecitabine + Ra223 (range 3-12) and 12 in the capecitabine arm (range 1-12). 94/95 prescribed Ra223 cycles were administered. No dose limiting toxicities were seen in phase IB and no patients developed grade ≥ III diarrhoea. Gastrointestinal, haematological and palmer-planter erthyrodysesthesia adverse events were similar in both arms. Although formal statistical comparisons were not made, changes in bone turnover markers, the times to extra-skeletal progression and bone disease progression, and the frequency of symptomatic skeletal events were similar across the two treatment arms.

Conclusion

Capecitabine + Ra223 at the planned dose was safe and feasible in MBC patients with bone metastases. However, no efficacy signals were seen that might suggest greater efficacy of the combination over capecitabine alone clinically or biochemically.

Translational Strategies to Target Metastatic Bone Disease

Metastatic bone disease is a common and devastating complication to cancer, confounding treatments and recovery efforts and presenting a significant barrier to de-escalating the adverse outcomes associated with disease progression. Despite significant advances in the field, bone metastases remain presently incurable and contribute heavily to cancer-associated morbidity and mortality. Mechanisms associated with metastatic bone disease perpetuation and paralleled disruption of bone remodeling are highlighted to convey how they provide the foundation for therapeutic targets to stem disease escalation. The focus of this review aims to describe the preclinical modeling and diagnostic evaluation of metastatic bone disease as well as discuss the range of therapeutic modalities used clinically and how they may impact skeletal tissue.

Dose estimation after a mixed field exposure: Radium-223 and intensity modulated radiotherapy

INTRODUCTION

Radium-223 dichloride ([²²³Ra]RaCl₂), a radiopharmaceutical that delivers α-particles to regions of bone metastatic disease, has been proven to improve overall survival of men with metastatic castration resistant prostate cancer (mCRPC). mCRPC patients enrolled on the ADRRAD clinical trial are treated with a mixed field exposure comprising radium-223 (²²³Ra) and intensity modulated radiotherapy (IMRT). While absorbed dose estimation is an important step in the characterisation of wider systemic radiation risks in nuclear medicine, uncertainties remain for novel radiopharmaceuticals such as ²²³Ra.

METHODS

24-Colour karyotyping was used to quantify the spectrum of chromosome aberrations in peripheral blood lymphocytes of ADRRAD patients at incremental times during their treatment. Dicentric equivalent frequencies were used in standard models for estimation of absorbed blood dose. To account for the mixed field nature of the treatment, existing models were used to determine the ratio of the component radiation types. Additionally, a new approach (M-FISH_LET), based on the ratio of cells containing damage consistent with high-LET exposure (complex chromosomal exchanges) and low-LET exposure (simple exchanges), was used as a pseudo ratio for ²²³Ra:IMRT dose.

RESULTS

Total IMRT estimated doses delivered to the blood after completion of mixed radiotherapy (after 37 IMRT fractions and two [²²³Ra]RaCl₂ injections) were in the range of 1.167 ± 0.092 and 2.148 ± 0.096 Gy (dose range across all models applied). By the last treatment cycle analysed in this study (four [²²³Ra]RaCl₂ injections), the total absorbed ²²³Ra dose to the blood was estimated to be between 0.024 ± 0.027 and 0.665 ± 0.080 Gy, depending on the model used. Differences between the models were observed, with the observed dose variance coming from inter-model as opposed to inter-patient differences. The M-FISH_LET model potentially overestimates the ²²³Ra absorbed blood dose by accounting for further PBL exposure in the vicinity of metastatic sites.

CONCLUSIONS

The models presented provide initial estimations of cumulative dose received during incremental IMRT fractions and [²²³Ra]RaCl₂ injections, which will enable improved understanding of the doses received by individual patients. While the M-FISH_LET method builds on a well-established technique for external exposures, further consideration is needed to evaluate this method and its use in assessing non-targeted exposure by ²²³Ra after its localization at bone metastatic sites.

Updates in Management of Bone Metastatic Disease in Primary Solid Tumors with Systemic Therapies

PURPOSE OF REVIEW

The purpose of this review is to highlight novel and impactful discoveries in systemic treatment of bone metastatic disease in solid tumors published within the past 5 years.

RECENT FINDINGS

Major developments in systemic treatment of bone metastatic disease in solid tumors include evidence that decreasing frequency of dosing zoledronic acid in metastatic breast and prostate cancer maintains efficacy in preventing skeletal-related events while decreasing costs. The landmark findings on the use of Radium-223 to treat metastatic prostate cancer were reported in 2013. Recently, it has been found that not all systemic therapy combinations with Radium-223 are necessarily safe or effective unless bone-targeted therapy is also included in the regimen. More cost-effective dosing intervals of zoledronic acid and efficacy and safety nuances of combination radiopharmaceutical and chemotherapy treatment have been better delineated.

Imaging Biomarkers in Lung Cancer with 68Ga-DOTATATE, 18F-Fluoride, and 18F-FDG PET/CT Scans and the Theranostics Paradigm

Lung cancer is the number 1 cause of cancer deaths in the United States. The prognosis is quite grim with the exception of stage 1. When faced with several failed therapeutic regimens and rapid progression of the disease, considering alternative therapies such as radiopharmaceutical therapies may be an option. We describe the case of a 36-y-old man with lung adenocarcinoma who had imaging molecular characterization of his disease with ¹⁸F-FDG, ⁶⁸Ga-DOTATATE, and ¹⁸F-fluoride PET/CT scans that were able to shed some light on molecular characterization of his disease and serve as a guide to potential targeted or personalized radiopharmaceutical therapeutic options.

Radiopharmaceutical therapy in cancer: clinical advances and challenges

Radiopharmaceutical therapy (RPT) is emerging as a safe and effective targeted approach to treating many types of cancer. In RPT, radiation is systemically or locally delivered using pharmaceuticals that either bind preferentially to cancer cells or accumulate by physiological mechanisms. Almost all radionuclides used in RPT emit photons that can be imaged, enabling non-invasive visualization of the biodistribution of the therapeutic agent. Compared with almost all other systemic cancer treatment options, RPT has shown efficacy with minimal toxicity. With the recent FDA approval of several RPT agents, the remarkable potential of this treatment is now being recognized. This Review covers the fundamental properties, clinical development and associated challenges of RPT.

Targeted Alpha Therapy: Current Clinical Applications

α-Emitting radionuclides have been approved for cancer treatment since 2013, with increasing degrees of success. Despite this clinical utility, little is known regarding the mechanisms of action of α particles in this setting, and accurate assessments of the dosimetry underpinning their effectiveness are lacking. However, targeted alpha therapy (TAT) is gaining more attention as new targets, synthetic chemistry approaches, and α particle emitters are identified, constructed, developed, and realized. From a radiobiological perspective, α particles are more effective at killing cells compared to low linear energy transfer radiation. Also, from these direct effects, it is now evident from preclinical and clinical data that α emitters are capable of both producing effects in nonirradiated bystander cells and stimulating the immune system, extending the biological effects of TAT beyond the range of α particles. The short range of α particles makes them a potent tool to irradiate single-cell lesions or treat solid tumors by minimizing unwanted irradiation of normal tissue surrounding the cancer cells, assuming a high specificity of the radiopharmaceutical and good stability of its chemical bonds. Clinical approval of ²²³RaCl₂ in 2013 was a major milestone in the widespread application of TAT as a safe and effective strategy for cancer treatment. In addition, ²²⁵Ac-prostate specific membrane antigen treatment benefit in metastatic castrate-resistant prostate cancer patients, refractory to standard therapies, is another game-changing piece in the short history of TAT clinical application. Clinical applications of TAT are growing with different radionuclides and combination therapies, and in different clinical settings. Despite the remarkable advances in TAT dosimetry and imaging, it has not yet been used to its full potential. Labeled ²²⁷Th and ²²⁵Ac appear to be promising candidates and could represent the next generation of agents able to extend patient survival in several clinical scenarios.

Targeted α-Therapy in Cancer Management: Synopsis of Preclinical and Clinical Studies

The approval of ²²³Ra dichloride (²²³RaCl₂) in 2013 was a principal event in introducing targeted α-therapy as a form of safe and effective management strategy in cancer. There is an increasing interest in research and development of new targeted α-therapy agents spearheaded by advancements in cancer biology, radiochemistry, and availability of clinically relevant α particles. There are active clinical studies on sequencing or combining ²²³RaCl₂ with other drug regimens in the setting of metastatic prostate cancer and in other cancers such as osteosarcoma and bone-dominant breast cancer. Targeted α-therapy strategy is also being actively explored through many preclinical and few early clinical studies using ²²⁵Ac, ²¹³Bi, ²¹¹At, ²²⁷Th, and ²¹²Pb. Investigations incorporating ²²⁵Ac are more robust and active at this time with promising results. The author provide a brief synopsis of the preclinical and clinical studies in the rapidly evolving field of targeted α-therapy in cancer management.

Bone Metastases in Neuroendocrine Neoplasms: From Pathogenesis to Clinical Management

Bone represents a common site of metastases for several solid tumors. However, the ability of neuroendocrine neoplasms (NENs) to localize to bone has always been considered a rare and late event. Thanks to the improvement of therapeutic options, which results in longer survival, and of imaging techniques, particularly after the introduction of positron emission tomography (PET) with gallium peptides, the diagnosis of bone metastases (BMs) in NENs is increasing. The onset of BMs can be associated with severe skeletal complications that impair the patient’s quality of life. Moreover, BMs negatively affect the prognosis of NEN patients, bringing out the lack of curative treatment options for advanced NENs. The current knowledge on BMs in gastro-entero-pancreatic (GEP) and bronchopulmonary (BP) NENs is still scant and is derived from a few retrospective studies and case reports. This review aims to perform a critical analysis of the evidence regarding the role of BMs in GEP- and BP-NENs, focusing on the molecular mechanisms underlining the development of BMs, as well as clinical presentation, diagnosis, and treatment of BMs, in an attempt to provide suggestions that can be used in clinical practice.