Colorectal cancer, commonly known as bowel cancer, remains one of the leading causes of cancer-related mortality worldwide. Despite notable advances in treating cancers such as melanoma and lung cancer through immunotherapy, progress in bowel cancer has been hampered by the tumor’s ability to “turn off” immune responses. Professor Aideen Ryan, an esteemed figure in tumor immunology at University of Galway’s College of Medicine, Nursing and Health Sciences, highlights that limitations in current immunotherapy interventions have left many patients battling advanced disease with scant options and poor prognoses.

The fundamental breakthrough from this research centers on the tumor microenvironment—specifically, the role of structural stromal cells that surround and support cancerous growth. These stromal cells were previously considered passive scaffolding but are now revealed as active participants in immune evasion. They deploy a sophisticated biochemical mechanism to suppress two critical players in tumor immunity: natural killer (NK) cells and macrophages. This suppression effectively disarms the body’s innate ability to combat the tumor.

Delving deeper into biochemical pathways, the study elucidates the role of sialoglycans—complex sugar molecules that coat the stromal cells. These sialoglycans interact with Siglec receptors on immune cells, creating an inhibitory signal that dampens immune activation. This glycan-receptor interaction emerges as a novel immune checkpoint distinct from the well-characterized PD-1/PD-L1 axis, and is responsible for inducing an “immune brake” within the tumor milieu.

The researchers identified a critical enzyme responsible for synthesizing these Siglec-binding sialoglycans on stromal cells, effectively orchestrating the immune suppression. By introducing sialidase drugs—enzymes that cleave sialoglycans—the team was able to disrupt this inhibitory signaling, reactivating NK cells and macrophages. This reactivation led not only to tumor shrinkage but also inhibited metastasis, the often-lethal spread of cancer cells beyond the colon.

Such findings underscore the potential of targeting the sialoglycan-Siglec axis as a completely new therapeutic avenue. It offers hope to overcome the long-standing resistance of colorectal cancers to immunotherapeutic approaches. The study’s interdisciplinary approach, combining immunology, oncology, biochemistry, and pharmaceutical innovation through collaboration with Palleon Pharmaceuticals, emphasizes translational medicine’s capacity to transform laboratory discoveries into clinical realities.

Professor Ryan emphasizes that the complexity of tumor-immune interactions had masked this crucial immune checkpoint until now. Her team’s work reveals how cancer, far from being a static entity, actively reprograms the nearby stromal cells to sabotage immune defenses. This shift in understanding could revolutionize how clinicians approach bowel cancer treatment, moving away from solely attacking tumor cells to also modulating their surrounding environment.

The implications extend beyond colorectal cancer, as the sialoglycan-Siglec pathway represents a fundamental immune regulatory mechanism that might be exploited by other tumor types. Dr. Michael O’Dwyer, Scientific Director of the University of Galway Cancer Centre, calls this research exemplary for illustrating how cellular cross-talk within tumors facilitates cancer progression and immune evasion, highlighting the promise of innovations emerging from collaborative cancer research hubs.

Industry leaders also recognize the significance of these findings. Jim Broderick, CEO of Palleon Pharmaceuticals, notes that the role of sialoglycans in cancer-associated immunosuppression has been underappreciated until recently. By developing drugs that disrupt sialoglycan-mediated immune checkpoints, the pharmaceutical industry is poised to open new frontiers in immuno-oncology, potentially benefiting patients with colorectal and other refractory cancers.

This pioneering research gains further visibility through public engagement, featuring in the Breakthrough Cancer Research exhibition “Cancer Revolution: Science, Innovation and Hope” held at Stephen’s Green Shopping Centre. The exhibition showcases captivating microscopy imagery and 3D tumor models that visually narrate how stromal cells suppress immune activity in bowel cancer, ultimately illustrating the science behind a potential new class of immunotherapy treatments.

While the pathway from discovery to clinical application is complex, the significance of these findings offers renewed optimism. By targeting an entirely new immune checkpoint within the tumor microenvironment, there is tremendous potential to enhance the efficacy of immunotherapies for colorectal cancer patients globally, who have long awaited breakthroughs beyond conventional chemotherapy and radiation.

This study marks a monumental stride in tumor immunology, reshaping dogma around the tumor microenvironment’s role in immune modulation. It invites the scientific community and clinicians alike to reexamine therapeutic strategies, and opens the door to tailored immunotherapies that can better harness the innate power of the immune system against one of the world’s most deadly cancers.

Subject of Research: People
Article Title: Stromal cells modulate innate immune cell phenotype and function in colorectal cancer via the Sialic acid/Siglec axis
News Publication Date: 20-Oct-2025
Web References: Journal for ImmunoTherapy of Cancer
Image Credits: Andrew Downes, Xposure
Keywords: colorectal cancer, bowel cancer, immunotherapy, tumor immunology, stromal cells, sialoglycans, Siglec receptors, immune checkpoint, natural killer cells, macrophages, metastasis, sialidase drugs, tumor microenvironment

Lung cancer remains a leading cause of cancer-related mortality worldwide, with many patients typically diagnosed at an advanced stage when treatment options are limited. Over the past decade, immunotherapy, particularly PD-1 and PD-L1 inhibitors, has emerged as a beacon of hope, fundamentally altering the therapeutic landscape. However, patient responses remain highly variable, prompting scientists to search for biomarkers that can reliably forecast treatment outcomes.

In this retrospective cohort study, researchers compiled an extensive dataset from 120 patients treated for advanced lung cancer between January 2019 and August 2024. These patients were carefully categorized into two groups based on whether they developed thyroid dysfunction during treatment. This stratification enabled an in-depth analysis of the relationship between TD occurrence and progression-free survival (PFS), as well as examination of baseline TSH levels as a predictive factor.

The results were striking. Patients who developed thyroid dysfunction exhibited significantly higher baseline TSH levels compared to their counterparts who did not experience any thyroid irregularities. Notably, the median baseline TSH in the TD group was 2.33 mIU/L, compared to 1.58 mIU/L in the non-TD group, indicating a substantial physiological difference prior to immunotherapy. This finding suggests that subclinical variations in thyroid function could foreshadow treatment-induced immune-related responses.

Equally noteworthy was the dramatic extension in progression-free survival among the TD subgroup. The median PFS measured 7.90 months in patients with thyroid dysfunction, markedly longer than the 4.87 months observed in those without TD. This differential was statistically significant, with a hazard ratio (HR) for disease progression of 0.499, reinforcing the protective association between TD and therapeutic success under PD-1/PD-L1 blockade.

When isolating patients exclusively treated with PD-1/PD-L1 inhibitors, these trends persisted robustly. Baseline TSH levels remained significantly elevated in those who developed thyroid dysfunction (median 2.16 mIU/L versus 1.52 mIU/L), and a similar PFS benefit was maintained (8.83 months versus 6.50 months). This correlation underscores the likelihood of thyroid dysfunction serving as a favorable prognostic biomarker within immunotherapy paradigms.

The mechanistic underpinnings of this association remain a subject of ongoing inquiry. One prevailing hypothesis involves the immune system’s heightened reactivity leading to collateral thyroid gland inflammation, a manifestation of immune-related adverse events. Such immune activation could simultaneously amplify anti-tumor responses, generating an intertwined therapeutic and autoimmune effect. Further research into this delicate immunologic balance could unveil novel strategies to optimize treatment while mitigating toxicity.

Clinicians may soon consider baseline TSH screening as a non-invasive, cost-effective tool to identify patients more likely to benefit from PD-1/PD-L1 inhibitors. Not only could this advance allow for tailored immunotherapy regimens, but it might also propel earlier detection and management of thyroid dysfunction, thereby improving overall patient quality of life.

This study adds to a growing body of evidence supporting the prognostic relevance of endocrine-related immune adverse events in cancer therapy. Beyond lung cancer, similar patterns have been reported in melanoma and renal cell carcinoma, highlighting a potential universal principle whereby immune-related endocrinopathies herald enhanced immunotherapy efficacy.

Yet, the retrospective nature of the study predicates a cautious interpretation. Prospective clinical trials are urgently needed to validate these findings and to understand the longitudinal impact of thyroid dysfunction on survival, treatment adherence, and broader clinical outcomes. Integration of comprehensive immune profiles, genomic data, and thyroid antibody status could add further granularity to predictive models.

Moreover, these insights reinforce the critical importance of multidisciplinary care in oncology. Endocrinologists, oncologists, and immunologists must collaborate closely to monitor thyroid function vigilantly throughout immunotherapy cycles. Early intervention to correct thyroid imbalances could prevent severe complications without compromising anti-cancer efficacy.

The implications of this research extend beyond immediate clinical management, inviting exploration into the biology of immune checkpoint inhibitors and their systemic effects. It raises essential questions about the crossroads of autoimmunity and antitumor immunity, potentially inspiring novel biomarkers and therapeutic targets that capitalize on immune modulation.

As immunotherapy continues to mature as a cornerstone of cancer treatment, personalized approaches informed by biomarkers such as TSH levels promise to enhance precision medicine. Harnessing the predictive power of thyroid dysfunction not only illuminates the path forward for lung cancer care but may also unlock benefits for myriad malignancies responsive to immune checkpoint blockade.

In summary, this seminal study compellingly associates baseline thyroid function with the efficacy of PD-1/PD-L1 inhibitors in advanced lung cancer. Patients who develop thyroid dysfunction demonstrate superior progression-free survival, with baseline TSH emerging as a predictive indicator for TD occurrence. These findings herald a transformative leap towards integrating endocrine parameters into oncologic decision-making and improving immunotherapy outcomes on a global scale.

The landscape of advanced lung cancer treatment is evolving rapidly, and the spotlight on thyroid dysfunction exemplifies the intricate interplay between systemic physiology and cancer biology. As research continues to unravel these complex connections, clinicians and patients alike may reap the benefits of more effective, individualized, and safer cancer therapies.

Subject of Research: The correlation between thyroid dysfunction and the efficacy of PD-1/PD-L1 inhibitors in advanced lung cancer patients, with emphasis on baseline TSH levels as a predictive biomarker.

Article Title: Thyroid dysfunction as a predictor of PD-1/PD-L1 inhibitor efficacy in advanced lung cancer.

Article References:
Wang, Y., Ma, X., Ma, J. et al. Thyroid dysfunction as a predictor of PD-1/PD-L1 inhibitor efficacy in advanced lung cancer. BMC Cancer 25, 791 (2025). https://doi.org/10.1186/s12885-025-14097-w

Image Credits: Scienmag.com

DOI: https://doi.org/10.1186/s12885-025-14097-w