Aging is the most significant risk factor for chronic diseases. This is largely due to the accumulation of senescent cells, damaged cells that stop dividing but persist in tissues. While cellular senescence is a natural mechanism to prevent the spread of damaged or cancerous cells, its prolonged presence contributes to chronic inflammation, tissue dysfunction, and degenerative diseases. Over time, these "zombie" cells accumulate as the immune system's ability to clear them declines, promoting conditions such as arthritis, cardiovascular disease, diabetes, and neurodegeneration.
The senescence-associated secretory phenotype (SASP), a mix of inflammatory molecules released by senescent cells, disrupts normal tissue function and accelerates aging. Researchers have identified senolytics, a class of drugs that selectively eliminate these dysfunctional cells, as a potential strategy to delay or prevent multiple age-related disorders simultaneously, rather than tackling each disease individually.
Preclinical studies have demonstrated that senolytic drugs can effectively eliminate senescent cells in animal models, leading to improvements in various age-related conditions. For instance, research has shown that removing these cells in mice results in delayed progression of diseases such as osteoporosis, muscle loss, and cardiac dysfunction.¹
Mechanism of Action
Senescent cells stop dividing and resist apoptosis by activating survival pathways while releasing inflammatory molecules (SASP) that cause tissue damage. Senolytics counter this by blocking these survival mechanisms, forcing senescent cells to undergo apoptosis while sparing healthy cells. Eliminating these harmful cells reduces inflammation, restores tissue function, and slows aging.
For example, BCL-2 inhibitors such as Navitoclax block anti-apoptotic proteins, while tyrosine kinase inhibitors like Dasatinib interfere with the survival pathways that senescent cells depend on. Natural flavonoids, including Quercetin and Fisetin, can suppress SASP and induce apoptosis in certain senescent cells.²
Importantly, senolytic therapy is administered in a "hit-and-run" manner, meaning the drugs are given intermittently to minimize side effects and allow tissues to regenerate healthy cells.
Key Senolytic Compounds
Different senolytic agents have been identified, each targeting specific types of senescent cells.
1. Dasatinib (D) – An FDA-approved cancer drug that eliminates senescent fat progenitor and endothelial cells. In animal models, a single dose improved cardiovascular function within days.
2. Quercetin (Q) – A natural flavonoid that targets endothelial and bone-marrow-derived senescent cells, often combined with Dasatinib for broader senolytic action.
3. Fisetin – A plant-derived senolytic that extends lifespan in mice and reduces systemic inflammation. It is considered one of the safest senolytic candidates and is currently in human clinical trials for frailty reduction.
4. Navitoclax (ABT-263) – A potent BCL-2 inhibitor that eliminates senescent cells in bone marrow and blood vessels but carries a risk of thrombocytopenia (low platelet count).³
5. UBX1325 (Foselutoclax) – A newer senolytic targeting senescent cells in the retina, currently being tested for age-related macular degeneration and diabetic macular edema.⁴
UBX1325 (foselutoclax) is an investigational senolytic developed by UNITY Biotechnology for retinal diseases like diabetic macular edema (DME) and wet age-related macular degeneration (AMD). It inhibits BCL-xL, a protein that helps senescent cells survive, promoting their selective elimination in the retina. In clinical trials, UBX1325 has shown promise.
A Phase 1 study confirmed its safety and potential benefits for retinal endothelial cells in DME patients. In the Phase 2 BEHOLD trial, a single injection led to significant improvements in Best Corrected Visual Acuity (BCVA) over 48 weeks.The Phase 2 ENVISION study in wet AMD did not meet its primary endpoint but suggested greater efficacy...
(All Rights Reserved)