Metastasis, the dissemination of cancer cells from the primary tumor to distant organs, accounts for the majority of cancer-related mortalities. Despite rigorous treatments including surgery and chemotherapy, residual microscopic cancerous cells evade eradication and seed secondary tumors, complicating patient outcomes and posing a significant therapeutic challenge. Conventional strategies have struggled to selectively inhibit this metastatic cascade without causing systemic toxicity. The newly developed CO prodrug, designated CO-116, offers a promising avenue by releasing precisely controlled, low concentrations of carbon monoxide directly within the body, circumventing the risks associated with inhaled CO and metal-containing CO-releasing molecules.

Dr. Nancy Du, the senior author and associate professor of pathology and laboratory medicine at Weill Cornell Medicine, emphasizes the paradigm-shifting nature of this approach. Carbon monoxide, though infamous for its toxicity at high levels, is endogenously synthesized in mammalian systems as a critical signaling molecule. Harnessing this physiological production, CO-116 has been meticulously designed to deliver CO in a controlled manner, thereby leveraging its anti-metastatic properties while mitigating potential adverse effects. This balance is pivotal for transforming CO from a hazardous gas to a therapeutic agent.

The initial inspiration for this study stems from Dr. Du’s team’s prior work published in 2022, which demonstrated that low-dose carbon monoxide impedes metastatic dissemination in preclinical models. However, the translation of these findings into clinical practice was hindered by the difficulty in safely and effectively administering CO. Inhalation therapies present challenges in achieving precise dosing and bear inherent safety hazards. Past research explored metal-based carbon monoxide-releasing molecules (CORMs), but these approaches often left behind toxic metal residues, limiting their clinical viability.

To circumvent these obstacles, the team collaborated with Dr. Binghe Wang from Georgia State University, an expert in synthetic chemistry, to develop a metal-free prodrug capable of releasing carbon monoxide upon intravenous administration. This prodrug remains inert until metabolized in the body, ensuring targeted CO delivery. The molecular design of CO-116 optimizes pharmacokinetics and bioavailability while eliminating the risks associated with metal toxicity. Such chemical innovation marks a significant leap in the field of CO-based therapeutics.

Subsequent preclinical trials employing various murine models afflicted with pancreatic and triple-negative breast cancer revealed that CO-116 effectively curtailed the progression of metastatic tumors, particularly within intricately vascularized organs like the liver and lungs. Notably, these therapeutic benefits manifested without detectable systemic toxicity, weight loss, or behavioral alterations in treated animals, underscoring the safety profile of the prodrug. These findings underscore the clinical promise of CO-116 as a non-invasive metastasis inhibitor.

More intriguing was the discovery that the frequency and timing of CO-116 administration considerably influenced therapeutic outcomes. Administering smaller doses more frequently proved superior to an equivalent weekly bolus dose, indicating that dynamic CO delivery kinetics optimize anti-metastatic efficacy. This insight could reshape dosing paradigms for future clinical trials and influence the development of personalized CO-based therapeutic regimens tailored to tumor biology and patient physiology.

The researchers delved deeper into the mechanistic underpinnings driving CO-116’s anti-metastatic potency. Their investigations spotlighted the heme-responsive gene 1 (HRG1) protein, a pivotal transporter responsible for heme uptake in cancer cells. Heme, an iron-containing porphyrin complex, is indispensable for myriad cellular processes including oxygen transport and mitochondrial respiration. By attenuating HRG1 expression, CO-116 disrupts heme acquisition, thereby impairing cancer cell metabolic networks and metastatic capabilities.

Functional studies employing genetic manipulation of cancer cells elaborated on the relationship between HRG1 levels and CO sensitivity. Overexpression of HRG1 conferred increased metastatic aggressiveness and resistance to carbon monoxide therapy, whereas silencing HRG1 significantly impeded metastatic growth and enhanced responsiveness to the prodrug. These data suggest HRG1 not only functions as a therapeutic target but may also serve as a predictive biomarker, identifying patients who stand to benefit the most from CO-based treatments.

While the preclinical data are compelling, substantial research remains to translate these findings into human clinical practice. Future investigations must rigorously evaluate the long-term safety profile of CO-116, exploring potential cumulative effects and ensuring no latent toxicities arise over extended treatment durations. Additionally, optimizing dosing schedules through pharmacodynamic and pharmacokinetic studies will be essential to maximize efficacy while minimizing adverse events.

Furthermore, elucidating whether the anti-metastatic effects of CO-116 persist after cessation of therapy will determine its practicality as an adjuvant treatment. The ultimate goal is to integrate CO prodrugs as adjunctive interventions in cancer management, administered post-surgery or chemotherapy to thwart recurrence and improve survival outcomes for patients suffering from aggressive malignancies historically resistant to conventional therapies.

Dr. Du reflects on the broader implications of their discovery, highlighting the transformative impact of deploying a non-inhaled, metal-free carbon monoxide prodrug with demonstrable efficacy across multiple cancer models. This study not only validates CO’s therapeutic potential but also ignites a new frontier in cancer metastasis research, charting a course toward therapies that strike at the heart of cancer’s lethality—the spread and colonization of distant organs.

Supported in part by a Manhasset Women’s Coalition Against Breast Cancer Research Grant and bolstered through NIH funding for the prodrug synthesis in Dr. Wang’s laboratory, this research exemplifies cross-disciplinary collaboration and innovative chemistry driving precision medicine. The strides made herein herald a promising era wherein carbon monoxide’s dual nature is harnessed judiciously to save lives rather than threaten them.

In conclusion, the development of CO-116 represents a pioneering advancement in anti-metastatic treatment strategies, merging chemical ingenuity with biological insight to combat cancer’s deadliest trait. As research progresses and clinical trials emerge, this metal-free carbon monoxide prodrug could become an indispensable weapon in the arsenal against metastatic pancreatic and triple-negative breast cancers, offering renewed hope to patients worldwide confronting these formidable diseases.

Subject of Research: Development of a metal-free carbon monoxide prodrug to inhibit metastasis in pancreatic and triple-negative breast cancer.

Article Title: A Metal-Free Carbon Monoxide Prodrug Suppresses Metastatic Progression in Preclinical Models of Pancreatic and Triple-Negative Breast Cancer.

News Publication Date: March 20, 2026.

Web References:

• Original Study: https://advanced.onlinelibrary.wiley.com/doi/10.1002/advs.202519898
• Prior Research: https://www.sciencedirect.com/science/article/abs/pii/S0304383522003159

Keywords: Carbon monoxide, CO prodrug, metastasis inhibition, pancreatic cancer, triple-negative breast cancer, HRG1, heme transporter, metal-free therapeutics, anti-cancer therapy, controlled drug delivery, preclinical cancer models, cancer metastasis

Bladder cancer is a significant health concern, characterized by its high recurrence rate and potential for invasion into surrounding tissues and distant organs. Understanding the molecular underpinnings that drive bladder cancer progression is critical for developing effective treatment strategies. In their study, the authors aim to demystify the role of circRNAs in the pathology of bladder cancer, highlighting how ACVR2A specifically interacts with microRNAs to influence cellular behaviors.

CircRNA ACVR2A appears to function as a tumor suppressor in bladder cancer. Unlike linear RNAs, the unique structure of circRNAs, formed by backsplicing, confers stability and allows them to act as scaffolds for protein interactions or as sponges for microRNAs. By sequestering certain microRNAs, circRNAs can modulate the downstream effects of these regulatory RNAs, effectively altering gene expression profiles within cancer cells. The study posits that ACVR2A’s interaction with miR-626 is pivotal to its role in tumor suppression.

The authors provide compelling data illustrating that overexpression of ACVR2A significantly inhibits the proliferation and migration of bladder cancer cells in vitro. This finding is coupled with in vivo studies showing that forced expression of ACVR2A reduces tumor growth and metastatic potential in murine models. Through these comprehensive analyses, the study delineates a crucial pathway wherein ACVR2A exerts its effects via miR-626, which in turn targets the EYA4 gene involved in oncogenic signaling pathways.

One of the striking aspects of this research is the focus on the miR-626/EYA4 axis in the context of bladder cancer. MiR-626 is recognized as a crucial regulator, influencing various cellular processes, including apoptosis and cell cycle progression. By understanding how ACVR2A modulates the availability of miR-626, researchers can begin to piece together a broader picture of the regulatory networks at play in bladder cancer biology. The implications extend beyond mere tumor biology; they challenge existing paradigms regarding RNA functions and open the door to novel diagnostic and therapeutic strategies.

The study also underscores the importance of circRNAs in cancer pathology, suggesting that their role extends beyond mere transcriptional noise. The authors emphasize that circRNAs, such as ACVR2A, are dynamically expressed and can adapt to changes in the tumor microenvironment, potentially influencing therapeutic responses. This adaptive capability raises interesting questions about the potential for targeting circRNAs as a means of enhancing cancer treatment efficacy while mitigating resistance.

Moreover, the authors addressed the need for further investigation into the mechanisms through which ACVR2A exerts its effects on bladder cancer cells. They advocate for more extensive studies that explore the broader implications of circRNA interactions with various microRNAs and their downstream targets. Such investigations could unveil new therapeutic targets and establish detailed cellular networks that are pivotal in cancer progression.

The significance of this research cannot be overstated, especially in light of the growing burden of bladder cancer globally. The findings encourage a paradigm shift in our approach to understanding cancer biology, highlighting the necessity of integrating circRNA investigation into mainstream oncological research. This shift could lead to the identification of novel biomarkers for early diagnosis and provide a basis for therapeutic advancements directed at circRNA modulation.

As we venture into an era characterized by personalized medicine, the insights derived from such studies hold promise for tailored treatment strategies that leverage the unique molecular profiles of individual tumors. The potential for circRNA-based therapies, which could either restore the function of tumor suppressive circRNAs like ACVR2A or inhibit oncogenic circRNAs, represents a frontier that warrants further exploration.

The study conducted by Dong, W., Bi, J., Liu, H., and their colleagues serves as a compelling illustration of how circRNAs can intersect with critical microRNA pathways to influence cancer cell behavior. It exemplifies a growing field of research that seeks to unravel the complexities of non-coding RNAs in human health and disease. The enthusiasm surrounding these findings is palpable, and they offer a glimpse of the future of cancer treatments that may emerge from a deeper understanding of the RNA landscape in tumors.

In conclusion, the research delineating the role of circular RNA ACVR2A in bladder cancer presents a beacon of hope for innovative therapies. With its ability to engage with key regulatory microRNAs and suppress aggressive tumor traits, ACVR2A stands as a potential target for future pharmacological interventions. As researchers continue to decipher the intricate dance of circRNAs and their interactions within the cellular milieu, there is optimism for breakthroughs that could redefine our strategies in combating cancer.

Subject of Research: The role of circular RNA ACVR2A in suppressing bladder cancer proliferation and metastasis.

Article Title: Correction: Circular RNA ACVR2A suppresses bladder cancer cells proliferation and metastasis through miR-626/EYA4 axis.

Article References: Dong, W., Bi, J., Liu, H. et al. Correction: Circular RNA ACVR2A suppresses bladder cancer cells proliferation and metastasis through miR-626/EYA4 axis. Mol Cancer 24, 309 (2025). https://doi.org/10.1186/s12943-025-02528-y

Image Credits: AI Generated

DOI: 10.1186/s12943-025-02528-y

Keywords: Circular RNA, ACVR2A, Bladder cancer, miR-626, EYA4, Tumor suppression, Cancer therapeutics, Non-coding RNA, Oncology, Gene regulation.

Gastric cancer remains a formidable clinical challenge worldwide, attributed largely to its aggressive nature and resistance to conventional therapies. Scientists have long sought to identify molecules capable of curbing tumor growth and metastasis without incurring debilitating side effects. This study centers on quercetin, a compound richly found in fruits and vegetables, that has demonstrated promising anti-cancer properties in various malignancies but whose exact mechanisms in gastric cancer were previously unclear.

The investigative team employed two human gastric cancer cell lines—AGS and MKN-45—to model the disease environment in vitro. These cells were treated with quercetin alongside well-established chemotherapeutic agents paclitaxel and cisplatin to provide a comparative framework for efficacy. The post-treatment analyses were comprehensive, assessing cellular viability, apoptosis, cell cycle disruption, migration, and invasive potential.

Quantitative techniques revealed that quercetin significantly diminished cell viability across both GC cell lines, paralleling the effects observed with paclitaxel and cisplatin. Flow cytometric assays substantiated these findings by demonstrating an increase in programmed cell death and notable cell cycle arrest. Additionally, the flavonoid impaired the cells’ intrinsic capabilities to invade and migrate, two hallmarks of metastatic potential. These functional bioassays provided compelling evidence of quercetin’s multi-modal anti-tumor activity.

At the molecular level, the researchers zoomed in on a metabolic cascade associated with immune evasion and tumor progression—tryptophan catabolism via the indoleamine 2,3-dioxygenase 1 enzyme (IDO1). Dysregulation of this enzymatic pathway leads to the accumulation of kynurenine, a metabolite known to activate the aryl hydrocarbon receptor (AhR), fostering an immunosuppressive microenvironment conducive to cancer growth.

Advanced gene and protein expression analyses demonstrated a coordinated downregulation of IDO1, its paralog IDO2, tryptophan 2,3-dioxygenase (TDO), kynurenine 3-monooxygenase (KMO), and AhR following treatment with quercetin. This concerted suppression disrupted the metabolic axis, potentially reinstating immune surveillance mechanisms and inhibiting oncogenic signaling pathways modulated by AhR activation.

The study’s findings hold significant translational implications. By attenuating the IDO1-Kynurenine-AhR axis, quercetin not only hampers the intrinsic proliferative and migratory capacities of gastric cancer cells but may also reprogram the tumor microenvironment towards a less permissive state. This dual action underscores the flavonoid’s potential as a complementary or alternative therapeutic agent, especially for patients who experience adverse effects from standard chemotherapy.

Comparative analysis showed that quercetin’s efficacy paralleled traditional chemotherapeutic drugs in several key aspects, yet it is presumed to carry a more favorable toxicity profile, given its dietary origin and established safety in humans. The study advocates further preclinical and clinical assessments to verify dosing regimens, bioavailability, and combinational strategies that include quercetin for optimal patient outcomes.

Moreover, the research invites a broader reconsideration of targeted metabolic pathways in oncology. Tryptophan metabolism and AhR signaling have emerged as critical nodes in cancer biology, interfacing metabolism, immunity, and cell behavior. Interventions like quercetin that can modulate these axes hold promise for undermining tumor resilience and enhancing immune-mediated clearance.

The methodology employed in this research exemplifies rigorous cellular and molecular interrogation. CCK-8 assays quantified cell viability changes, while flow cytometry enabled precise measurement of apoptosis rates and cell cycle alterations, providing mechanistic insights at the cellular level. The wound healing and Transwell assays served to quantify migration and invasion respectively, critical functional parameters linked to metastatic competence.

Molecular interrogation was conducted using quantitative PCR and Western blotting, tools that quantified gene transcription and protein translation of targeted enzymes and receptors within the tryptophan metabolism pathway. This multi-layered approach ensured robustness of conclusions, revealing quercetin’s capacity to suppress mRNA and protein levels synchronously.

The novelty of this study lies in identifying quercetin as a modulator of the IDO1-Kynurenine-AhR axis specifically in gastric cancer—a pathway previously implicated predominantly in immune regulation but now underscored as a direct influencer of aggressive tumor phenotypes. By delineating this link, the authors pave the way for a novel class of therapeutics aimed at metabolic reprogramming.

Further exploration into the pharmacodynamics and pharmacokinetics of quercetin will be vital to translate these promising in vitro findings into clinically effective interventions. The modulation of the tryptophan metabolism axis by flavonoids may extend beyond gastric cancer, opening vistas for cross-cancer therapeutic strategies exploiting metabolic vulnerabilities.

The potential integration of quercetin into combinatorial treatment regimens, possibly enhancing the efficacy of existing chemotherapeutic agents while mitigating their side effects, could revolutionize the management pipeline. Precision targeting of metabolic enzymes may overcome treatment resistance, a frequent barrier to successful cancer control.

In summation, this research heralds a promising horizon in oncological therapeutics where naturally derived compounds like quercetin can exert profound anti-cancer effects by targeting intricate metabolic and signaling networks. The suppression of the IDO1-Kynurenine-AhR axis emerges as a pivotal mechanism through which gastric cancer proliferation and migration can be restrained, offering hope for improved prognoses.

The implications extend beyond biological curiosity, touching on the clinical promise of integrating dietary phytochemicals into the armamentarium against one of the deadliest cancers globally. As the scientific community intensifies its focus on tumor metabolism, studies such as this underscore the necessity of holistic approaches marrying natural compounds with precision oncology.

Subject of Research: Gastric cancer cell proliferation and migration inhibition via modulation of IDO1-mediated tryptophan metabolism.

Article Title: Quercetin inhibits gastric cancer cell proliferation and migration and is associated with the suppression of the IDO1-Kynurenine-AhR axis.

Article References: Zhu, M., Hu, Q., Lu, Y. et al. Quercetin inhibits gastric cancer cell proliferation and migration and is associated with the suppression of the IDO1-Kynurenine-AhR axis. BMC Cancer (2025). https://doi.org/10.1186/s12885-025-15308-0

Image Credits: Scienmag.com

DOI: https://doi.org/10.1186/s12885-025-15308-0

Merkel cell carcinoma is a neuroendocrine malignancy arising from the outermost layer of the skin, frequently appearing on sun-exposed areas such as the face, arms, and legs. Characterized by its rarity—affecting fewer than three individuals per million—and rapid invasiveness, MCC presents major therapeutic challenges. Historically, the disease’s prognosis has been grim, with fewer than 50% of patients surviving five years post diagnosis. This trial, therefore, represents an important stride toward improving survival outcomes by establishing pembrolizumab’s role in the adjuvant setting.

Pembrolizumab, a monoclonal antibody that inhibits the programmed death-1 (PD-1) receptor, works by disrupting a critical immune checkpoint exploited by cancer cells to evade destruction. By blocking PD-1, pembrolizumab reinvigorates the immune system’s T cells, allowing them to recognize and eradicate malignant cells much like they would viral pathogens. This mechanism has already transformed treatment landscapes across several tumor types, including melanoma and non-small cell lung cancer.

The trial, designated ECOG-ACRIN EA6174, enrolled 293 patients between 2018 and 2023 across multiple leading cancer centers throughout the United States. All subjects underwent surgical excision of their Merkel cell tumors and were randomized equally to receive either postoperative pembrolizumab infusions or observation without immunotherapy. Additionally, some patients received radiotherapy based on physician discretion. The study’s primary endpoints were recurrence-free survival and distant metastasis-free survival, key indicators of treatment efficacy.

Data analysis revealed a numerical advantage favoring pembrolizumab in terms of five-year survival without cancer recurrence, with 73% of treated patients remaining disease-free at two years, compared to 66% in the control group. While this difference did not reach statistical significance, the trend hints at pembrolizumab’s potential benefit. More compellingly, the immunotherapy group exhibited a substantial 42% reduction in the risk of distant metastases, indicating a pronounced protection against the cancer’s spread to critical organs such as bones, liver, and lungs.

Dr. Janice Mehnert, lead investigator and director of the melanoma medical oncology program at Perlmutter Cancer Center, emphasized that this study constitutes the first robust evidence supporting postoperative immunotherapy’s ability to prevent systemic relapse in MCC. The results underscore pembrolizumab’s transformative potential to extend the period patients remain free from disease progression, which is crucial for a malignancy notorious for its aggressive dissemination.

One of the notable challenges addressed by this study involved the rarity of Merkel cell carcinoma. As NCI-designated rare tumors demand extensive collaboration across institutions to accrue meaningful patient numbers, this multicenter trial stands as a model for orchestrated, large-scale investigations. The comprehensive recruitment enabled statistically meaningful insights, fueling optimism about expanding immunotherapy indications for rare cancers.

Technically, the study’s design as a randomized controlled trial ensures that the clinical findings are both scientifically rigorous and clinically applicable. The inclusion of a sizeable cohort and standardized follow-up procedures strengthens the reliability of the data. Importantly, the mechanism by which PD-1 inhibition counteracts immune evasion aligns with fundamental immunologic principles, validating pembrolizumab’s therapeutic rationale in this context.

From a translational research perspective, these findings might pave the way for future explorations into combining pembrolizumab with other modalities such as radiation or targeted agents to augment antitumor immunity further. Moreover, the study highlights the critical role of immune checkpoints in MCC pathobiology, suggesting novel biomarker-driven strategies could enhance patient selection and response prediction.

Despite the promising outcomes, Dr. Mehnert and her colleagues caution that further research is warranted, especially to elucidate long-term survival benefits and to optimize patient management protocols. Future trials might also investigate resistance mechanisms that allow certain MCC tumors to evade immunotherapy, enabling the refinement of combinatorial approaches.

The trial was supported by significant funding from the National Institutes of Health, including the National Cancer Institute’s National Clinical Trials Network and specific grant R50CA282100. Collaborative efforts involved prominent oncologists and researchers from institutions such as Dana-Farber Cancer Institute, Cleveland Clinic, Stanford University, and Weill Cornell Medicine among others, reflecting the multidisciplinary nature of the endeavor.

In conclusion, the ECOG-ACRIN EA6174 trial offers a critical advance in the adjuvant treatment of Merkel cell carcinoma. Pembrolizumab has demonstrated compelling potential to reduce the risk of distant metastases post-surgery, marking a shift toward more effective immunotherapeutic interventions in rare skin cancers. This study’s results, soon to be presented at the European Society for Medical Oncology meeting, provide hope for improved survival and quality of life for patients confronting this formidable malignancy.

Subject of Research: People

Article Title: (Not provided)

News Publication Date: (Not provided)

Web References: (Not provided)

References: (Not provided)

Image Credits: (Not provided)

Keywords: Skin cancer, Cancer immunotherapy