Pathobiology and prevention of cancer chemotherapy-induced bone growth arrest, bone loss, and osteonecrosis

Cancer chemotherapy has been recognized as one severe risk factor that influences bone growth and bone mass accumulation during childhood and adolescence. This article reviews on the importance of this clinical issue, current understanding of the underlying mechanisms for the skeletal defects and potential preventative strategies. Both clinical and basic studies that appeared from 1990 to 2010 were reviewed for bone defects (growth arrest, bone loss, osteonecrosis, and/or fractures) caused by paediatric cancer chemotherapy. As chemotherapy has become more intensive and achieved greater success in treating paediatric malignancies, skeletal complications such as bone growth arrest, low bone mass, osteonecrosis, and fractures during and/or after chemotherapy have become a problem for some cancer patients and survivors particularly those that have received high dose glucocorticoids and methotrexate. While chemotherapy-induced skeletal defects are likely multi-factorial, recent studies suggest that different chemotherapeutic agents can directly impair the activity of the growth plate and metaphysis (the two major components of the bone growth unit) through different mechanisms, and can alter bone modeling/remodeling processes via their actions on bone formation cells (osteoblasts), bone resorption cells (osteoclasts) and bone "maintenance" cells (osteocytes). Intensive use of multi-agent chemotherapy can cause growth arrest, low bone mass, fractures, and/or osteonecrosis in some paediatric patients. While there are currently no specific strategies for protecting bone growth during childhood cancer chemotherapy, regular BMD monitoring and exercise are have been recommended, and possible adjuvant treatments could include calcium/vitamin D, antioxidants, bisphosphonates, resveratrol, and/or folinic acid.     

Preclinical and clinical developments for combination treatment of influenza

Antiviral drugs are an important measure of control for influenza in the population, particularly for those that are severely ill or hospitalised. The neuraminidase inhibitor (NAI) class of drugs, including oseltamivir, have been the standard of care (SOC) for severe influenza illness for many years. The approval of drugs with novel mechanisms of action, such as baloxavir marboxil, is important and broadens potential treatment options for combination therapy. The use of antiviral treatments in combination for influenza is of interest; one potential benefit of this treatment strategy is that the combination of drugs with different mechanisms of action may lower the selection of resistance due to treatment. In addition, combination therapy may become an important treatment option to improve patient outcomes in those with severe illness due to influenza or those that are immunocompromised. Clinical trials increasingly evaluate drug combinations in a range of patient cohorts. Here, we summarise preclinical and clinical advances in combination therapy for the treatment of influenza with reference to immunocompromised animal models and clinical data in hospitalised patient cohorts where available. There is a wide array of drug categories in development that have also been tested in combination. Therefore, in this review, we have included polymerase inhibitors, monoclonal antibodies (mAbs), host-targeted therapies, and adjunctive therapies. Combination treatment regimens should be carefully evaluated to determine whether they provide an added benefit relative to effectiveness of monotherapy and in a variety of patient cohorts, particularly, if there is a greater chance of an adverse outcome. Safe and effective treatment of influenza is important not only for seasonal influenza infection, but also if a pandemic strain was to emerge.     

Aromatase inhibitors and bone

The decrease in estrogen levels with the use of aromatase inhibitors results in an increase in the rate of bone remodelling. This result in an acceleration of bone loss, and probably to an increase in the risk of fractures. The risk of fracture is particularly high in the older woman and in the woman with a low bone mineral density. We have a number of proven treatments for the treatment of postmenopausal osteoporosis and it is likely that some of these, particularly bisphosphonates, could be effective at preventing bone loss with aromatase inhibitors.     

Combined therapies in osteoporosis: bisphosphonates and vitamin D-hormone analogs

During the last two decades, the development of new, highly effective therapeutics (e.g. bisphosphonates, SERMs, strontium ranelate and PTH) has significantly extended the spectrum of osteoporosis therapy. However, the interest of combining bone-active agents and/or Vitamin D and calcium is still being debated, and is restricted to a very marginal set of compounds (Alendronate and native Vitamin D). On the other hand, Vitamin D-hormone analogs, calcitriol, and alfacalcidol, have repeatedly demonstrated their effectiveness in being valuable alternatives compared to native Vitamin D in this setting. A growing amount of data documents the pre-clinical and clinical efficacies of combinations of bisphosphonates with calcitriol, or with alfacalcidol in primary and secondary osteoporosis. This exhaustive review of the available animal and clinical data aimed at comparing the theoretical with demonstrated absolute and relative benefits of those therapeutic approaches. Most of the pre-clinical and clinical data in PMOP suggest significant, clinical improvements in response to combination therapies versus monotherapies in postmenopausal osteoporosis. As a investigated by most of the currently available trials, a daily dose of alendronate 10 mg or a weekly dose of Alendronate 70 m plus alfacalcidol 0.5-1.0 microg daily plus alfacalcidol 0.5 microg seems to surpass other combinations when BMD and bone metabolism markers are considered. A synergy with bisphosphonates in reducing the fracture episodes may lie in the pleiotropic effects of D-hormone analogs on musculoskeletal, immunological and neurological systems. Negative interactions between both drugs have not yet been reported, while a reduction of hypercalcuria episodes has been noted in combination therapies, as compared to monotherapies involving high doses of Vitamin D, calcitriol, or alfacalcidol. Based on the possible reduction of periodic safety checks of calcemia, an improved compliance could then be expected, which would, in turn, generate a better end result. However, to document this, long-term, high quality comparative studies with factorial designs are needed to determine which role this alternative should play in the management of postmenopausal, male, and glucocorticoid-induced osteoporosis.     

Estrogens and age-related memory decline in rodents: what have we learned and where do we go from here?

The question of whether ovarian hormone therapy can prevent or reduce age-related memory decline in menopausal women has been the subject of much recent debate. Although numerous studies have demonstrated a beneficial effect of estrogen and/or progestin therapy for certain types of memory in menopausal women, recent clinical trials suggest that such therapy actually increases the risk of cognitive decline and dementia. Because rodent models have been frequently used to examine the effects of age and/or ovarian hormone deficiency on mnemonic function, rodent models of age-related hormone and memory decline may be useful in helping to resolve this issue. This review will focus on evidence suggesting that estradiol modulates memory, particularly hippocampal-dependent memory, in young and aging female rats and mice. Various factors affecting the mnemonic response to estradiol in aging females will be highlighted to illustrate the complications inherent to studies of estrogen therapy in aging females. Avenues for future development of estradiol-based therapies will also be discussed, and it is argued that an approach to drug development based on identifying the molecular mechanisms underlying estrogenic modulation of memory may lead to promising future treatments for reducing age-related mnemonic decline.     

Meta-Analysis of Clinical Fracture Risk Reduction of Antiosteoporosis Drugs: Direct and Indirect Comparisons and Meta-Regressions

ObjectiveAntiosteoporotic drug (AOD) trials have variabilities in duration and fracture risks. This study evaluated AOD’s versus controls regarding reduction in relative rates and rate differences in vertebral and hip fractures and comparative costs.MethodsPrimary randomized controlled trials of antiosteoporotic drugs in postmenopausal women with documentation of vertebral fracture rates or hip fracture rates were extracted from meta-analyses and PubMed through February 2021. Direct and indirect meta-analyses and meta-regressions analyzed the fracture reductions.ResultsThere were 24 randomized controlled trials of drug versus placebo (73 862 women) and 10 randomized controlled trials of drug versus drug. The reductions in the relative rates of vertebral fractures were significant for antiresorptive (alendronate, risedronate, zoledronate, denosumab, and raloxifene) and anabolic (teriparatide, abaloparatide, and romosozumab) drugs. Denosumab, teriparatide, and abaloparatide were more effective in reducing vertebral fracture rates than oral bisphosphates (all P < .05) but were not more effective in reducing vertebral fracture rates than zoledronate. The reductions in hip fracture rates were significant for alendronate, denosumab, and zoledronate (all P < .05), without significant differences among drugs. Anabolic drugs did not show significant hip fracture rate reduction. Meta-regression of rate differences enabled the calculation of costs per vertebral fracture prevented, which were estimated at >$100 000 for anabolic drugs and between $2289 and $28 947 for antiresorptive drugs. Many direct drug versus drug trials were underpowered to demonstrate benefits of one drug over another.ConclusionThis study suggests goal-directed, cost-effective therapies relative to patient risk for vertebral and hip fractures. Anabolic drugs are better at preventing vertebral fractures than oral bisphosphonates. Anabolic drugs are not superior to zoledronate or denosumab and are substantially more expensive. When comparing drugs that prevented hip fractures, there was no statistical benefit of any drug.     

Pros and cons of existing treatment modalities in osteoporosis: a comparison between tibolone,SERMs and estrogen (+/-progestogen) treatments

Tibolone, selective estrogen receptor modulators (SERMs) like tamoxifen and raloxifene, and estrogen (±progestogen) treatments prevent bone loss in postmenopausal women. They exert their effects on bone via the estrogen receptor (ER) and the increase in bone mass is due to resorption inhibition. The effect of SERMs on bone mineral density is less than that with the other treatments, but the SERM raloxifene still has a positive effect on vertebral fractures. In contrast to tibolone and estrogens (±progestogen), SERMs do not treat climacteric complaints, whilst estrogen plus progestogen treatments cause a high incidence of bleeding. Estrogen plus progestogen combinations have compromising effects on the breast. Tibolone and SERMs do not stimulate the breast or endometrium. Unlike SERMs, tibolone does not posses antagonistic biological effects via the ER in these tissues. Estrogenic stimulation in these tissues is prevented by local metabolism and inhibition of steroid metabolizing enzymes by tibolone and its metabolites. SERMs and estrogen (±progestogen) treatments increase the risk of venous thromboembolism (VTE), whilst estrogen (±progestogen) combinations have unwanted effects on cardiovascular events. So far, no detrimental effects of tibolone have been observed with respect to VTE or cardiovascular events. The clinical profile of tibolone therefore has advantages over those of other treatment modalities. It is also clear that tibolone is a unique compound with a specific mode of action and that it belongs to a separate class of compounds that can best be described as selective, tissue estrogenic activity regulators (STEARs).     

乳腺癌双膦酸盐辅助治疗临床研究进展

乳腺癌是女性发病率和死亡率最高的恶性肿瘤,复发和远处转移仍是导致患者死亡的首位原因,而双膦酸盐作为一种骨质吸收抑制剂,能够抑制破骨细胞介导的骨质吸收,在多种实体肿瘤骨转移及多发性骨髓瘤等恶性疾病所致的骨相关事件治疗中起重要作用。近年来大量体外、体内实验表明双膦酸盐还具有抑制肿瘤细胞生长、粘附、播散和侵润,降低肿瘤细胞膜稳定性、促进肿瘤细胞凋亡等直接抗肿瘤作用以及抑制肿瘤血管生成、激活免疫细胞对肿瘤细胞的杀伤等间接抗肿瘤作用,基于这些基础研究结果已经开展了一系列针对双膦酸盐辅助治疗乳腺癌的临床试验研究,本文就近年相关临床试验研究进展做简要综述。     

Emerging trends in COVID-19 treatment: learning from inflammatory conditions associated with cellular therapies

Coronavirus disease 2019 (SARS-CoV2) is an active global health threat for which treatments are desperately being sought. Even though most people infected experience mild to moderate respiratory symptoms and recover with supportive care, certain vulnerable hosts develop severe clinical deterioration. While several drugs are currently being investigated in clinical trials, there are currently no approved treatments or vaccines for COVID-19 and hence there is an unmet need to explore additional therapeutic options. At least three inflammatory disorders or syndromes associated with immune dysfunction have been described in the context of cellular therapy. Specifically, Cytokine Release Syndrome (CRS), Immune Reconstitution Inflammatory Syndrome (IRIS), and Secondary Hemophagocytic Lymphohistiocytosis (sHLH) all have clinical and laboratory characteristics in common with COVID19 and associated therapies that could be worth testing in the context of clinical trials. Here we discuss these diseases, their management, and potential applications of these treatment in the context of COVID-19. We also discuss current cellular therapies that are being evaluated for the treatment of COVID-19 and/or its associated symptoms.     

Clinical usefulness of bisphosphonates in oncology: treatment of bone metastases, antitumoral activity and effect on bone resorption markers

The present article overviews the role of bisphosphonates for the treatment and prevention of bone metastases and their antiangiogenic effects and antitumoral activity. The skeleton is a frequent and clinically relevant site of metastasis in cancer patients. The major events related to bone metastases include bone pain, bone loss, hypercalcemia, spinal cord compression, and fractures. On the basis of their radiographic features, bone metastases are classified as osteoblastic, osteoclastic, or mixed. The primary goals of treatment of bone metastases are reduction of the risk of pathological fractures and other skeletal-related events, and pain control. Bisphosphonates are used to prevent pathological fractures by inhibition of osteoclasts. Recent studies suggest that bisphosphonates have some direct antitumoral activity, mainly mediated through the blockade of angiogenic pathways. Further clinical studies are needed to determine the optimal treatment duration, timing and schedule of bisphosphonates, assess their role as adjuvant therapy for the prevention of bone metastases, and establish their antiangiogenic activity in association with standard cytotoxic and hormonal drugs for treatment of patients with advanced disease.     

Selective Estrogen Receptor Modulators Suppress Hif1α Protein Accumulation in Mouse Osteoclasts

Anti-bone resorptive drugs such as bisphosphonates, the anti-RANKL antibody (denosumab), or selective estrogen receptor modulators (SERMs) have been developed to treat osteoporosis. Mechanisms underlying activity of bisphosphonates or denosumab in this context are understood, while it is less clear how SERMs like tamoxifen, raloxifene, or bazedoxifene inhibit bone resorption. Recently, accumulation of hypoxia inducible factor 1 alpha (Hif1α) in osteoclasts was shown to be suppressed by estrogen in normal cells. In addition, osteoclast activation and decreased bone mass seen in estrogen-deficient conditions was found to require Hif1α. Here, we used western blot analysis of cultured osteoclast precursor cells to show that tamoxifen, raloxifene, or bazedoxifene all suppress Hif1α protein accumulation. The effects of each SERM on osteoclast differentiation differed in vitro. Our results suggest that interventions such as the SERMs evaluated here could be useful to inhibit Hif1α and osteoclast activity under estrogen-deficient conditions.     

Recommendations on the management of fragility fracture risk in women younger than 70 years

The risk for fragility fracture represents a problem of enormous magnitude. It is estimated that only a small fraction of women with this risk take the benefit of preventive measures. The relationship between estrogen and bone mass is well known as they are the other factors related to the risk for fracture. There are precise diagnostic methods, including a tool to diagnose the risk for fracture. Yet there continues to be an under-diagnosis, with the unrecoverable delay in instituting preventive measures. Women under the age of 70 years, being much more numerous than those older, and having risk factors, are a group in which it is essential to avoid that first fragility fracture. Today it is usual not to differentiate between the treatment and the prevention of osteoporosis since the common aim is to prevent fragility fractures. Included in this are women with osteoporosis or with low bone mass and increased risk for fracture, for whom risk factors play a primary role. There is clearly controversy over the type of treatment and its duration, especially given the possible adverse effects of long-term use. This justifies the concept of sequential treatment, even more so in women under the age of 70, since they presumably will need treatment for many years. Bone metabolism is age-dependent. In postmenopausal women under 70 years of age, the increase in bone resorption is clearly predominant, related to a sharp drop in estrogens. Thus a logical treatment is the prevention of fragility fractures by hormone replacement therapy (HRT) and, in asymptomatic women, selective estradiol receptor modulators (SERMs). Afterwards, there is a period of greater resorption, albeit less intense but continuous, when one could utilise anti-resorptive treatments such as bisphosphonates or denosumab or a dual agent like strontium ranelate. Bone formation treatment, such as parathyroid hormone (PTH), in women under 70 years will be uncommon. That is because it should be used in cases where the formation is greatly diminished and there is a high risk for fracture, something found in much older women.     

The role of parathyroid hormone in the management of osteoporosis

It has been over 2 years since parathyroid hormone (PTH 1-34) was approved in the US and Europe for the treatment of osteoporosis in postmenopausal women and men. Clinical experience with this peptide has enhanced confidence in its use and its application in specific clinical scenarios. There is no doubt that PTH 1-34 is safe and effective in reducing spine and non-vertebral fractures in men and women. However, the lack of several randomized placebo-controlled trials and their relatively short duration raise several questions that still need to be answered. This paper reviews three major areas of uncertainty: (1) Is there significant heterogeneity in the bone density response of individuals to PTH? If so, what factors are important predictors? (2) What other regimens are available for PTH use? (3) What, if anything, should the clinician do after PTH is discontinued? Answers to these questions will undoubtedly lead to even greater utilization of this drug and some of its future derivatives.     

Overview of adjuvant trials of aromatase inhibitors in early breast cancer

The third-generation aromatase inhibitors are an important class of drugs for use in adjuvant therapy for postmenopausal women with resected estrogen receptor positive breast cancer. Multiple large prospective randomized trials have established their value in this setting and provided guidance for their use in clinical management. This review will outline the trials that have provided evidence on the value of the aromatase inhibitors in the adjuvant setting as well as the ongoing trials that will expand our knowledge of how to use them most effectively.     

乳腺癌双膦酸盐辅助治疗临床研究进展

乳腺癌是女性发病率和死亡率最高的恶性肿瘤,复发和远处转移仍是导致患者死亡的首位原因,而双膦酸盐作为一种骨质吸收抑制剂,能够抑制破骨细胞介导的骨质吸收,在多种实体肿瘤骨转移及多发性骨髓瘤等恶性疾病所致的骨相关事件治疗中起重要作用。近年来大量体外、体内实验表明双膦酸盐还具有抑制肿瘤细胞生长、粘附、播散和侵润,降低肿瘤细胞膜稳定性、促进肿瘤细胞凋亡等直接抗肿瘤作用以及抑制肿瘤血管生成、激活免疫细胞对肿瘤细胞的杀伤等间接抗肿瘤作用,基于这些基础研究结果已经开展了一系列针对双膦酸盐辅助治疗乳腺癌的,陆床试验研究,本文就近年相关临床试验研究进展做简要综述。     

Bisphosphonates and risk of atrial fibrillation: a meta-analysis

Introduction  

Bisphosphonates are the most commonly used drugs for the prevention and treatment of osteoporosis. Although a recent FDA review of the results of clinical trials reported no clear link between bisphosphonates and serious or non-serious atrial fibrillation (AF), some epidemiologic studies have suggested an association between AF and bisphosphonates.     

Aromatase inhibitors and arthralgia

In several large adjuvant clinical trials it has been demonstrated that substitution (eventually addition) of aromatase inhibitors (AIs) provides an improved outcome of endocrine-sensitive breast cancer over tamoxifen alone. Nevertheless, arthralgia induced by the AIs is one of the most frequent side effects in hormonal therapy. It is characterized by tenosynovial changes and is more frequent in patients in clinical practice than previously appreciated in adjuvant clinical trials. AI-related arthralgia may be related to estrogen deprivation, but estrogen replacement is not an option for these women. Therefore standard painkillers, NSAIDs (COX2 inhibitors), week opioids and other interventions (vitamin D, calcium, bisphosphonates, exercise, acupuncture, complementary and alternative approaches, eventually switch to another endocrine drug) are used for managing this treatment-related side effect, and improve adherence and quality of life among breast cancer survivors.     

Estrogens and women's health: interrelation of coronary heart disease, breast cancer and osteoporosis

The determinants of blood levels of estrogen, estrogen metabolites, and relation to receptors and post-transitional effects are the likely primary cause of breast cancer. Very high risk women for breast cancer can now be identified by measuring bone mineral density and hormone levels. These high risk women have rates of breast cancer similar to risk of myocardial infarction. They are candidates for SERM therapies to reduce risk of breast cancer. The completion of the Women's Health Initiative and other such trials will likely provide a definite association of risk and benefit of both estrogen alone and estrogen-progesterone therapy, coronary heart disease, osteoporotic fracture, and breast cancer. The potential intervention of hormone replacement therapy, obesity, or weight gain and increased atherogenic lipoproteinemia may be of concern and confound the results of clinical trials. Estrogens, clearly, are important in the risk of bone loss and osteoporotic fracture. Obesity is the primary determinant of postmenopausal estrogen levels and reduced risk of fracture. Weight reduction may increase rates of bone loss and fracture. Clinical trials that evaluate weight loss should monitor effects on bone. The beneficial addition of increased physical activity, higher dose of calcium or vitamin D, or use of bone reabsorption drugs in coordination with weight loss should be evaluated. Any therapy that raises blood estrogen or metabolite activity and decreases bone loss may increase risk of breast cancer. Future clinical trials must evaluate multiple endpoints such as CHD, osteoporosis, and breast cancer within the study. The use of surrogate markers such as bone mineral density, coronary calcium, carotid intimal medial thickness and plaque, endothelial function, breast density, hormone levels and metabolites could enhance the evaluation of risk factors, genetic-environmental intervention, and new therapies.