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Preclinical evidence demonstrates that senescent cells accumulate with aging and that senolytics delay multiple age-related morbidities, including bone loss. Thus, we conducted a phase 2 randomized controlled trial of intermittent administration of the senolytic combination dasatinib plus quercetin (D + Q) in postmenopausal women ( n  = 60 participants). The primary endpoint, percentage changes at 20 weeks in the bone resorption marker C-terminal telopeptide of type 1 collagen (CTx), did not differ between groups (median (interquartile range), D + Q −4.1% (−13.2, 2.6), control −7.7% (−20.1, 14.3); P  = 0.611). The secondary endpoint, percentage changes in the bone formation marker procollagen type 1 N-terminal propeptide (P1NP), increased significantly (relative to control) in the D + Q group at both 2 weeks (+16%, P  = 0.020) and 4 weeks (+16%, P  = 0.024), but was not different from control at 20 weeks (−9%, P  = 0.149). No serious adverse events were observed. In exploratory analyses, the skeletal response to D + Q was driven principally by women with a high senescent cell burden (highest tertile for T cell p16 (also known as CDKN2A ) mRNA levels) in which D + Q concomitantly increased P1NP (+34%, P  = 0.035) and reduced CTx (−11%, P  = 0.049) at 2 weeks, and increased radius bone mineral density (+2.7%, P  = 0.004) at 20 weeks. Thus, intermittent D + Q treatment did not reduce bone resorption in the overall group of postmenopausal women. However, our exploratory analyses indicate that further studies are needed testing the hypothesis that the underlying senescent cell burden may dictate the clinical response to senolytics. ClinicalTrials.gov identifier: NCT04313634 . In a phase 2 randomized control trial, intermittent senolytic therapy administered to postmenopausal women did not result in a reduction in the bone resorption marker, serum CTx, compared to control at 20 weeks.

Cellular senescence is a stress response that restrains the growth of aged, damaged or abnormal cells. Thus, senescence has a crucial role in development, tissue maintenance and cancer prevention. However, lingering senescent cells fuel chronic inflammation through the acquisition of a senescence-associated secretory phenotype (SASP), which contributes to cancer and age-related tissue dysfunction. Recent progress in understanding senescence has spurred interest in the development of approaches to target senescent cells, known as senotherapies. In this Review, we evaluate the status of various types of senotherapies, including senolytics that eliminate senescent cells, senomorphics that suppress the SASP, interventions that mitigate senescence and strategies that harness the immune system to clear senescent cells. We also summarize how these approaches can be combined with cancer therapies, and we discuss the challenges and opportunities in moving senotherapies into clinical practice. Such therapies have the potential to address root causes of age-related diseases and thus open new avenues for preventive therapies and treating multimorbidities. Recent progress in understanding senescence has spurred interest in the development of approaches that target senescent cells. This Review assesses the current status of senotherapies, such as senolytics and senomorphics, how these approaches can be combined with cancer therapies, and the challenges and opportunities in moving senotherapies to clinical practice.

A wide range of diseases have been shown to be influenced by the accumulation of senescent cells, from fibrosis to diabetes, cancer, Alzheimer’s and other age-related pathologies. Consistent with this, clearance of senescent cells can prolong healthspan and lifespan in in vivo models. This provided a rationale for developing a new class of drugs, called senolytics, designed to selectively eliminate senescent cells in human tissues. The senolytics tested so far lack specificity and have significant off-target effects, suggesting that a targeted approach could be more clinically relevant. Here, we propose to use an extracellular epitope of B2M, a recently identified membrane marker of senescence, as a target for the specific delivery of toxic drugs into senescent cells. We show that an antibody–drug conjugate (ADC) against B2M clears senescent cells by releasing duocarmycin into them, while an isotype control ADC was not toxic for these cells. This effect was dependent on p53 expression and therefore more evident in stress-induced senescence. Non-senescent cells were not affected by either antibody, confirming the specificity of the treatment. Our results provide a proof-of-principle assessment of a novel approach for the specific elimination of senescent cells using a second generation targeted senolytic against proteins of their surfaceome, which could have clinical applications in pathological ageing and associated diseases.

Systemic deletion of senescent cells leads to robust improvements in cognitive, cardiovascular, and whole‐body metabolism, but their role in tissue reparative processes is incompletely understood. We hypothesized that senolytic drugs would enhance regeneration in aged skeletal muscle. Young (3 months) and old (20 months) male C57Bl/6J mice were administered the senolytics dasatinib (5 mg/kg) and quercetin (50 mg/kg) or vehicle bi‐weekly for 4 months. Tibialis anterior (TA) was then injected with 1.2% BaCl2 or PBS 7‐ or 28 days prior to euthanization. Senescence‐associated β‐Galactosidase positive (SA β‐Gal+) cell abundance was low in muscle from both young and old mice and increased similarly 7 days following injury in both age groups, with no effect of D+Q. Most SA β‐Gal+ cells were also CD11b+ in young and old mice 7‐ and 14 days following injury, suggesting they are infiltrating immune cells. By 14 days, SA β‐Gal+/CD11b+ cells from old mice expressed senescence genes, whereas those from young mice expressed higher levels of genes characteristic of anti‐inflammatory macrophages. SA β‐Gal+ cells remained elevated in old compared to young mice 28 days following injury, which were reduced by D+Q only in the old mice. In D+Q‐treated old mice, muscle regenerated following injury to a greater extent compared to vehicle‐treated old mice, having larger fiber cross‐sectional area after 28 days. Conversely, D+Q blunted regeneration in young mice. In vitro experiments suggested D+Q directly improve myogenic progenitor cell proliferation. Enhanced physical function and improved muscle regeneration demonstrate that senolytics have beneficial effects only in old mice. Senolytics improve muscle regeneration in old mice, while providing no benefit in young mice. Old mice display more satellite cells, reduced inflammation, a lower senescent cell burden, and increased gene expression of bioenergetic pathways relative to untreated old mice.

Background The role of senescence in disease contexts is complex, however there is considerable evidence that depletion of senescent cells improves outcomes in a variety of contexts particularly related to aging, cognition, and neurodegeneration. Much research has shown previously that inflammation can promote cellular senescence. Microglia are a central nervous system innate immune cell that undergo senescence with aging and during neurodegeneration. The contribution of senescent microglia to multiple sclerosis, an inflammatory neurodegenerative disease, is not clear, but microglia are strongly implicated in chronic active lesion pathology, tissue injury, and disease progression. Drugs that could specifically eliminate dysregulated microglia in multiple sclerosis are therefore of great interest to the field. Results A single-cell analysis of brain tissue from mice subjected to experimental autoimmune encephalomyelitis (EAE), a mouse model of CNS inflammation that models aspects of multiple sclerosis (MS), identified microglia with a strong transcriptional signature of senescence including the presence of BCL2-family gene transcripts. Microglia expressing Bcl2l1 had higher expression of pro-inflammatory and senescence associated genes than their Bcl2l1 negative counterparts in EAE, suggesting they may exacerbate inflammation. Notably, in human single-nucleus sequencing from MS, BCL2L1 positive microglia were enriched in lesions with active inflammatory pathology, and likewise demonstrated increased expression of immune genes suggesting they may be proinflammatory and contribute to disease processes in chronic active lesions. Employing a small molecule BCL2-family inhibitor, Navitoclax (ABT-263), significantly reduced the presence of microglia and macrophages in the EAE spinal cord, suggesting that these cells can be targeted by senolytic treatment. ABT-263 treatment had a profound effect on EAE mice: decreasing motor symptom severity, improving visual acuity, promoting neuronal survival, and decreasing white matter inflammation. Conclusion These results support the hypothesis that microglia and macrophages exhibit transcriptional features of cellular senescence in EAE and MS, and that microglia expressing Bcl2l1 demonstrate a proinflammatory signature that may exacerbate inflammation resulting in negative outcomes in neuroinflammatory disease. Depleting microglia and macrophages using a senolytic results in robust improvement in EAE disease severity, including across measures of neurodegeneration, inflammation, and demyelination, and may therefore represent a novel strategy to address disease progression in multiple sclerosis.

Cellular senescence, a state of stable cell cycle arrest accompanied by a complex senescence-associated secretory phenotype (SASP), is a fundamental biological process implicated as a key driver of lung aging and lung age-related diseases (LARDs). This review provides a comprehensive overview of the rapidly evolving field of senotyping based on cellular heterogeneity in lung development and aging in health and disease. It also delves into the molecular mechanisms driving senescence and SASP production, highlighting pathways such as p53/p21, p16INK4a/RB, mTOR, and p38 MAPK as therapeutic targets. The involvement of various novel SASP proteins, such as GDP15, cytokines/chemokines, growth factors, and DNA damage response proteins. We further highlight the effectiveness of senotherapeutics in mitigating the detrimental effects of senescent cell (SnC) accumulation within the lungs. It also outlines two main therapeutic approaches: senolytics, which selectively trigger apoptosis in SnCs, and senomorphics (also known as senostatics), which mitigate the detrimental effects of the SASP without necessarily removing the senescent cells. Various classes of senolytic and senomorphic drugs are currently in clinical trials including natural products (e.g., quercetin, fisetin, resveratrol) and repurposed drugs (e.g., dasatinib, navitoclax, metformin, rapamycin) that has demonstrated therapeutic promise in improving tissue function, alleviating LARDs, and extending health span. We discuss the future of these strategies in lung research and further elaborate upon the usability of novel approaches including HSP90 inhibitors, senolytic CAR-T cells, Antibody drug conjugate and galactose-modified prodrugs in influencing the field of personalized medicine in future. Overall, this comprehensive review highlights the progress made so far and the challenges faced in the field of cellular senescence including SnC heterogeneity, states of senescence, senotyping, immunosenescence, drug delivery, target specificity, long-term safety, and the need for robust cell-based biomarkers. Future perspectives, such as advanced delivery systems, and combination therapies, are considered critical for translating the potential of senotherapeutics into effective clinical applications for age-related pulmonary diseases/conditions.

Senescent cells accumulate throughout the body with advanced age, diseases and chronic conditions. They negatively impact health and function of multiple systems, including the central nervous system (CNS). Therapies that target senescent cells, broadly referred to as senotherapeutics, recently emerged as potentially important treatment strategies for the CNS. Promising therapeutic approaches involve clearing senescent cells by disarming their pro-survival pathways with ‘senolytics’; or dampening their toxic senescence-associated secretory phenotype (SASP) using ‘senomorphics’. Following the pioneering discovery of first-generation senolytics dasatinib and quercetin, dozens of additional therapies have been identified, and several promising targets are under investigation. Although potentially transformative, senotherapies are still in early stages and require thorough testing to ensure reliable target engagement, specificity, safety and efficacy. The limited brain penetrance and potential toxic side effects of CNS-acting senotherapeutics pose challenges for drug development and translation to the clinic. This Review assesses the potential impact of senotherapeutics for neurological conditions by summarizing preclinical evidence, innovative methods for target and biomarker identification, academic and industry drug development pipelines and progress in clinical trials.With ageing global populations, cellular senescence is gaining increasing attention as a therapeutic target. In their Review, Orr and colleagues discuss ongoing research into senescence in the central nervous system, including promising targets and drugs in development that aim to clear senescent cells or modulate their senescence-associated secretory phenotype.

Aging is a complex physiological process that profoundly affects the functionality of the musculoskeletal system, contributing to an increase in the incidence of diseases such as osteoporosis, osteoarthritis, and sarcopenia. Cellular senescence plays a crucial role in these degenerative processes, promoting chronic inflammation and tissue dysfunction through the senescence-associated secretory phenotype (SASP). Recently, senotherapeutics have shown promising results in improving musculoskeletal health. Natural compounds such as resveratrol, rapamycin, quercetin, curcumin, vitamin E, genistein, fisetin, and epicatechin act on key signaling pathways, offering protective effects against musculoskeletal decline. On the other hand, molecules such as dasatinib, navitoclax, UBX0101, panobinostat, and metformin have been shown to be effective in eliminating or modulating senescent cells. However, understanding the mechanisms of action, long-term safety, and bioavailability remain areas for further investigation. In this context, physical exercise emerges as an effective non-pharmacological countermeasure, capable of directly modulating cellular senescence and promoting tissue regeneration, representing an integrated strategy to combat age-related diseases. Therefore, we have provided an overview of the main anti-aging compounds and examined the potential of physical exercise as a strategy in the management of age-related musculoskeletal disorders. Further studies should focus on identifying synergistic combinations of pharmacological and non-pharmacological interventions to optimize the effectiveness of anti-aging strategies and promoting healthier musculoskeletal aging.

Ageing-associated functional decline of organs and increased risk for age-related chronic pathologies is driven in part by the accumulation of senescent cells, which develop the senescence-associated secretory phenotype (SASP). Here we show that procyanidin C1 (PCC1), a polyphenolic component of grape seed extract (GSE), increases the healthspan and lifespan of mice through its action on senescent cells. By screening a library of natural products, we find that GSE, and PCC1 as one of its active components, have specific effects on senescent cells. At low concentrations, PCC1 appears to inhibit SASP formation, whereas it selectively kills senescent cells at higher concentrations, possibly by promoting production of reactive oxygen species and mitochondrial dysfunction. In rodent models, PCC1 depletes senescent cells in a treatment-damaged tumour microenvironment and enhances therapeutic efficacy when co-administered with chemotherapy. Intermittent administration of PCC1 to either irradiated, senescent cell-implanted or naturally aged old mice alleviates physical dysfunction and prolongs survival. We identify PCC1 as a natural senotherapeutic agent with in vivo activity and high potential for further development as a clinical intervention to delay, alleviate or prevent age-related pathologies. The polyphenol procyanidin C1, a compound found in grape seeds, possesses senomorphic or senolytic activity and is shown to extend the healthspan and survival of old mice and in various models of senescence-associated disability.

Interlinked and fundamental aging processes appear to be a root-cause contributor to many disorders and diseases. One such process is cellular senescence, which entails a state of cell cycle arrest in response to damaging stimuli. Senescent cells can arise throughout the lifespan and, if persistent, can have deleterious effects on tissue function due to the many proteins they secrete. In preclinical models, interventions targeting those senescent cells that are persistent and cause tissue damage have been shown to delay, prevent or alleviate multiple disorders. In line with this, the discovery of small-molecule senolytic drugs that selectively clear senescent cells has led to promising strategies for preventing or treating multiple diseases and age-related conditions in humans. In this Review, we outline the rationale for senescent cells as a therapeutic target for disorders across the lifespan and discuss the most promising strategies—including recent and ongoing clinical trials—for translating small-molecule senolytics and other senescence-targeting interventions into clinical use. Cellular senescence has emerged as a promising therapeutic target for disorders across the lifespan; this Review highlights the most promising strategies for translating senescence-targeting interventions into clinical use in the near future.