Telomerase can overcome replicative senescence by elongation of telomeres but is also a specific element in most cancer cells. It is expressed more vastly than any other tumor marker. Telomerase as a tumor target inducing replicative immortality can be overcome by only one other mechanism: alternative lengthening of telomeres (ALT). This limits the probability to develop resistance to treatments. Moreover, telomerase inhibition offers some degree of specificity with a low risk of toxicity in normal cells. Nevertheless, only one telomerase antagonist reached late preclinical studies. The underlying causes, the pitfalls of telomerase-based therapies, and future chances based on recent technical advancements are summarized in this review. Based on new findings and approaches, we propose a concept how long-term survival in telomerase-based cancer therapies can be significantly improved: the TICCA (Transient Immediate Complete and Combinatory Attack) strategy.

Telomere is a protective structure located at the end of chromosomes of eukaryotes, involved in maintaining the integrity and stability of the genome. Telomeres play an essential role in cancer progression; accordingly, targeting telomere dynamics emerges as an effective approach for the development of cancer therapeutics. Targeting telomere dynamics may work through multifaceted molecular mechanisms; those include the activation of anti-telomerase immune responses, shortening of telomere lengths, induction of telomere dysfunction and constitution of telomerase-responsive drug release systems. In this review, we summarize a wide variety of telomere dynamics-targeted agents in preclinical studies and clinical trials, and reveal their promising therapeutic potential in cancer therapy. As shown, telomere dynamics-active agents are effective as anti-cancer chemotherapeutics and immunotherapeutics. Notably, these agents may display efficacy against cancer stem cells, reducing cancer stem levels. Furthermore, these agents can be integrated with the capability of tumor-specific drug delivery by the constitution of related nanoparticles, antibody drug conjugates and HSA-based drugs.

Telomeres are dynamic complexes at the ends of chromosomes that are made up of protective proteins and tandem repeating DNA sequences. In the large majority of cancer cells, telomere length is maintained by telomerase, an enzyme that elongates telomeres. Telomerase activation is seen in the majority of cancer, which permits uncontrol cell proliferation. About 90% of human malignancies show telomere dysfunction and telomerase reactivation; as a result, telomerase activation plays a special role as a practically universal stage on the way to malignancy. This review understands the structural and functional of telomere and telomerase, mechanisms of telomerase activation in oncogenesis, biomarkers and therapeutic targets. Therapeutic strategies targeting telomerase, including antisense oligonucleotides, G-quadruplex stabilizers, immunotherapy, small-molecule inhibitors, gene therapy, Telomerase-Responsive Drug Release System, have shown promise in preclinical and clinical settings. Advances in telomere biology not only illuminate the complex interplay between telomeres, telomerase, and cancer progression but also open avenues for innovative, targeted cancer therapies.

Telomeres play a crucial role in maintaining genomic stability in healthy cells. However, they gradually shorten during the cell cycle, leading to chromosomal instability. Telomere length and telomerase activity are vital factors that counteract cellular degradation in cancer development and tumor persistence. Telomerase, which is activated in most cancer cells due to telomerase catalytic subunit (hTERT) overexpression, serves as a universal biomarker that is essential for cancer cell growth and survival. The upregulation of hTERT, often associated with G > A mutations in its promoter region, is frequently implicated in cancer progression. Consequently, anti-telomerase therapy has been proposed as a potentially more efficacious alternative to conventional treatment. Small-molecule inhibitors have garnered significant attention owing to their selectivity or ability to modulate multiple proteins. However, challenges, such as low response rates, brief response durations, toxicity, and resistance persist. Several strategies have been proposed to target telomerase activity and the telomere structure. These include the utilization of G-quadruplex-stabilizing compounds and telomere-specific oligonucleotide inhibitors of telomerase such as GRN163L and T-oligos. Another therapeutic approach involves the use of biological antisense oligonucleotides that specifically inhibit hTERT and human telomerase RNA component genes, potentially reducing telomerase activity and generating robust DNA signals in cancer cells. Immunotherapy targeting hTERT represents a recent advancement in cancer treatments. This approach leverages the immune system to target cancer cells with high hTERT expression, thereby offering a potentially more reliable treatment strategy. This review provides an overview of current research on telomerase-targeting small-molecule inhibitors, antisense oligonucleotides, and immunotherapy, discussing their mechanisms, clinical applications, and prospects in cancer treatment.

tumors [ 81 – 83 ]. While conventional therapies may not target these cancer stem cells, progressive telomere shortening induced by combination or maintenance treatment with telomerase inhibitors would potentially impair their self-renewal properties. Recent studies have shown that telomerase inhibitors target cancer stem cell populations in multiple myeloma, prostate, brain, breast and pancreatic cancer [ 77 , 78 , 84 – 86 ]. Cancer stem cell populations were reduced in size [ 78 , 85 , 86 ], had reduced proliferation [ 84 ], shortened telomeres [ 78 , 86 ], and impaired ability to form characteristic free-floating spherical colonies [ 77 , 85 ] after treatment with the GRN163L telomerase inhibitor. These studies indicate that telomerase inhibition does disrupt cancer stem cell self renewal, and supports the hypothesis that telomerase inhibition will be a viable maintenance treatment to decrease disease recurrence following other therapies. 4. Telomerase-targeted immunotherapy Several telomerase-based immunotherapy strategies have been developed and many are in advanced clinical trials, making this a rapidly-progressing field of anti-telomerase cancer therapy [ 87 – 101 ]. Telomerase is an attractive target antigen for cancer immunotherapy because it is expressed almost universally in human cancers and is functionally required to sustain malignant tumor long-term growth [ 87 ]. In brief, anti-telomerase immunotherapy sensitizes immune cells to tumor cells expressing hTERT peptides as surface antigens via the human leukocyte antigen (HLA) class I pathway [ 102 ]. This causes an expansion of telomerase-specific CD8+ cytotoxic T lymphocytes (CTLs), directing the patient’s own immune system to target and kill telomerase positive tumor cells [ 101 , 103 ]. The immune response can be induced by exposure to antigen presenting cells that either overexpress immunogenic hTERT fragments [ 92 ] or have been pulsed with immunogenic hTERT peptides. To date, 26 different hTERT pe

<b>Background</b>: Melanoma outcomes have improved in recent years as a result of modern systemic therapies. A major molecular feature of melanoma is abnormal telomerase activation; this is most often caused by telomerase reverse transcriptase (TERT) promoter mutations, which occur in 50-82% of cases and are the most common noncoding alteration in this cancer. Telomerase maintains telomere length, allowing melanoma cells to avoid senescence and continue dividing. However, how telomerase activity influences melanoma cell doubling time remains unclear, and the pathways linking TERT expression to faster cell-cycle progression require further study. Although telomerase inhibitors show promise in preclinical models, their clinical use is limited by delayed cytotoxicity and resistance. <b>Materials and Methods</b>: A scoping review was conducted using Scopus, ScienceDirect, MEDLINE/PubMed, and CINAHL (Cumulative Index to Nursing and Allied Health Literature). Keywords included "telomerase," "melanoma," "cancer," "cell proliferation," and "doubling time," using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. <b>Results</b>: Telomerase-related biomarkers were found to correlate with disease stage and survival. Suggested therapeutic strategies include enzyme inhibitors, cytotoxic nucleotide incorporation, telomere destabilization, and immunotherapies such as peptide or dendritic cell vaccines, etc. <b>Conclusions</b>: Understanding both telomere-dependent and -independent TERT functions is essential for developing effective biomarkers and therapies that overcome resistance and slow melanoma progression.

Background: Plasma cells constitute the majority of tumor cells in multiple myeloma (MM) but lack the potential for sustained clonogenic growth. In contrast, clonotypic B cells can engraft and recapitulate disease in immunodeficient mice suggesting they serve as the MM cancer stem cell (CSC). These tumor initiating B cells also share functional features with normal stem cells such as drug resistance and self-renewal potential. Therefore, the cellular processes that regulate normal stem cells may serve as therapeutic targets in MM. Telomerase activity is required for the maintenance of normal a

Homologous recombination (HR), a mechanism to accurately repair DNA in normal cells, is deregulated in cancer. Elevated/deregulated HR is implicated in genomic instability and telomere maintenance, which are critical lifelines of cancer cells. We have previously shown that HR activity is elevated and significantly contributes to genomic instability in BAC. The purpose of this study was to evaluate therapeutic potential of HR inhibition, alone and in combination with telomerase inhibition, in BAC. We demonstrate that telomerase inhibition in BAC cells increases HR activity, RAD51 expression, an