By Billy Candra 
London, UK – In a significant scientific advancement, research led by Professor Sophia Karagiannis at King’s College London has illuminated the precise mechanisms by which a novel class of antibody treatment reactivates patients’ own immune cells to combat ovarian cancer. This groundbreaking study, published today in the esteemed journal Nature Communications, offers a deeper understanding of patient responses to this pioneering therapy and holds immense promise for individuals facing this challenging disease. The findings suggest a potential paradigm shift in immunotherapy, particularly for solid tumours where conventional treatments often fall short.
The Ovarian Cancer Conundrum: An Unmet Need
Ovarian cancer remains one of the most lethal gynaecological malignancies globally, often diagnosed at advanced stages due to its subtle and non-specific symptoms. According to Cancer Research UK, around 7,500 women are diagnosed with ovarian cancer each year in the UK, with survival rates significantly lower than many other cancers, particularly when diagnosed late. Globally, the World Health Organization estimates that ovarian cancer is the eighth most common cancer in women, and the 18th most common cancer overall, with a grim prognosis for many. Standard treatments typically involve surgery, often followed by chemotherapy. While these approaches can achieve initial remission, recurrence is common, and many patients eventually develop resistance to existing therapies, highlighting a critical unmet need for innovative treatment strategies.
Immunotherapy, a revolutionary approach that harnesses the body’s immune system to fight cancer, has transformed the landscape for several cancer types. However, its success in ovarian cancer and other solid tumours has been limited. The vast majority of antibody treatments currently approved for cancer are based on Immunoglobulin G (IgG) antibodies. While effective in some cancers, IgG antibodies have largely proven ineffective against ovarian cancer, underscoring the necessity for alternative approaches.
Pioneering a New Frontier: The Power of IgE
King’s College London researchers have emerged as global pioneers in developing a cancer treatment derived from a different type of antibody: Immunoglobulin E (IgE). Unlike the ubiquitous IgG, IgE is best known for its crucial role in allergic reactions and its capacity to stimulate immune cells to fight parasitic infections. A key distinction lies in its binding properties: while IgG antibodies primarily activate immune cells circulating in the blood, IgE antibodies exhibit an exceptionally strong and stable binding affinity to immune cells found directly within tissues, including the tumour microenvironment. This unique characteristic has positioned IgE as a compelling candidate for targeting solid tumours, where immune suppression within the tumour itself is a major hurdle.
Professor Karagiannis’s team has dedicated years to exploring how to harness these potent immune-boosting activities of IgE specifically against solid cancers. Their research culminated in the development of an IgE antibody named MOv18. The initial focus of their investigation was to understand MOv18’s ability to activate immune cells from ovarian cancer patients and its broader influence on the intricate tumour environment.
From Preclinical Promise to Clinical Trials: The MOv18 IgE Journey
The journey of MOv18 IgE from a laboratory concept to a promising clinical candidate is a testament to years of rigorous scientific inquiry and collaborative effort. Early preclinical studies, which were instrumental in guiding MOv18 IgE toward clinical testing, demonstrated the critical role of activating and migrating tumour-associated macrophages into cancer lesions for this antibody treatment to be effective. This foundational work laid the groundwork for the subsequent clinical evaluation.
MOv18 IgE treatment has already demonstrated encouraging early results in a Phase Ia clinical trial. This initial trial, meticulously designed and executed by King’s researchers in collaboration with the National Institute for Health and Care Research (NIHR) Guy’s and St Thomas’ Clinical Research Facility and Cancer Research UK’s Centre for Drug Development, focused primarily on assessing the safety and tolerability of MOv18 IgE, as well as establishing initial efficacy signals in a small group of patients.
During this Phase Ia trial, a remarkable outcome was observed: at low doses, MOv18 IgE led to the shrinkage of the tumour in a patient with ovarian cancer who had previously failed to respond to conventional therapies. This singular event, while from a small cohort, provided crucial early validation of the therapeutic potential of IgE and spurred the team to delve deeper into the precise biological mechanisms underlying the antibody’s action within the complex immune environment of ovarian cancer. The publication in Nature Communications marks a significant milestone, detailing this mechanistic understanding.
Deciphering the Mechanism: Reversing Immunosuppression
The multidisciplinary study, conducted at King’s in close collaboration with colleagues at Guy’s and St Thomas’ NHS Foundation Trust, the Medical University of Vienna, Fondazione IRCCS Instituto Nazionale dei Tumori, Milan, and SeromYx Systems, Inc, meticulously investigated how MOv18 IgE interacts with various immune cell populations in ovarian cancer patients. The primary focus was on macrophages, a type of immune cell typically responsible for fighting infections and eliminating microorganisms. However, in the context of cancer, these macrophages can be corrupted, reprogrammed by the tumour to suppress immune responses and even actively support tumour growth. This phenomenon creates an "immunosuppressive web" within the tumour microenvironment, shielding cancer cells from immune attack.
Previous research in animal models had hinted that MOv18 IgE could reactivate these corrupted macrophages, redirecting them to fight the cancer. To validate this crucial hypothesis in a human context, the research team undertook a series of sophisticated experiments. They first collected macrophages from healthy donors and then exposed these cells to cancerous fluid samples obtained from the peritoneal cavity—the primary site of ovarian cancer spread—of patients with ovarian cancer. Additionally, they isolated macrophages directly from these patient-derived cancerous fluid samples. All patient samples were ethically collected from Guy’s and St Thomas’ NHS Foundation Trust, ensuring direct clinical relevance.
In both experimental settings, the researchers consistently observed that ovarian cancer fluid profoundly suppressed the immune activity of macrophages. Critically, they discovered that MOv18 IgE possessed the unique ability to bind to and activate these suppressed macrophages, effectively empowering them to kill ovarian cancer cells. Furthermore, this IgE-mediated activation had a cascading effect: it reversed the suppressive influence of ovarian cancer macrophages on other vital immune cells known as T cells. T cells are paramount for orchestrating and maintaining long-term anti-cancer immune responses in patients, making their reactivation a pivotal step towards durable therapeutic benefits.
Dr. Gabriel Osborn, who conducted this pivotal research during his PhD studies at King’s College London, articulated the significance of these findings: "We found that in patients, ovarian cancer effectively reprogrammed macrophages away from their normal immune activation function. Instead, they formed an immunosuppressive web in association with T cells, which could severely restrict anti-cancer immunity. However, MOv18 IgE was able to induce patient macrophages to kill cancer cells and undergo a highly inflammatory activation, which crucially reversed their suppressive effects on T cells. This study adds vital patient-level information, validating what we had previously observed for MOv18 IgE in laboratory settings, and, for the first time, reveals that IgE-driven macrophage stimulation can activate the wider tumour immune system."
To further corroborate these laboratory findings, the team analyzed tumour biopsies from two patients who participated in the Phase Ia clinical trial. They compared biopsies taken before treatment with MOv18 IgE to those collected after treatment. The post-treatment samples revealed a noticeable increase in the numbers of both macrophages and T cells present within the tumour environment, providing compelling in vivo evidence that these two immune cell populations are indeed key players in the anti-tumour activity of MOv18 IgE. This direct observation from patient tissue strongly supports the proposed mechanism of action.
Expert Perspectives and the Road Ahead
The implications of this research resonate deeply within the oncology community. Professor Sophia Karagiannis, Professor of Translational Cancer Immunology and Immunotherapy at King’s College London and the senior author of the study, emphasized the foundational importance of understanding the underlying biology. "Understanding the biology of how a treatment works is essential for bringing treatments closer to patients," she stated. "We found that immune cells which are otherwise inhibited in the ‘microenvironment’ of the tumour, are directed by IgE to target the cancer cells. While we are still progressing with clinical testing in patients, it is imperative that we continue in our quest towards understanding how MOv18 IgE, and a wider panel of IgE-based antibodies we are studying, harness the immune system in different groups of patients and cancer types." This highlights the potential for a broader application of IgE-based therapies across various solid tumours.
Dr. Debra Josephs, a consultant medical oncologist at Guy’s and St Thomas’ NHS Foundation Trust and a co-author of the study, whose preclinical research studies guided MOv18 IgE to clinical testing, added, "Our focus is to deepen our understanding of the immune system and its interaction with cancer, with the goal of discovering better treatments for patients. During the preclinical development of MOv18 IgE we demonstrated the important role of activation and migration of tumour-associated macrophages into cancer lesions for this antibody treatment to be effective. This research marks an important next step in the development of MOv18 IgE by advancing our understanding of macrophage-mediated mechanisms, thus supporting the therapeutic potential of this novel antibody." Her perspective underscores the seamless translation from basic science to clinical application.
Professor James Spicer, Professor of Experimental Cancer Medicine at King’s College London, a consultant in medical oncology at Guy’s and St Thomas’ NHS Foundation Trust, and Chief Clinical Investigator of the MOv18 IgE Phase Ia trial, also a co-author of the study, articulated the urgent need for innovation. "We need to achieve better outcomes for our patients. Clear progress is being made by studying the immune system and the environment in which the cancer grows. In our ongoing research we are striving to understand how we can capitalize on the power of IgE to develop novel effective treatments, which will complement established IgG antibody drugs used in the clinic." His statement points towards a future where IgE therapies could work synergistically with existing treatments, offering more comprehensive and durable responses.
Funding and Collaboration: The Pillars of Discovery
This extensive and impactful research was made possible through the generous support of leading medical research organizations, including Cancer Research UK, the Medical Research Council, and Breast Cancer Now. These funding bodies play a crucial role in enabling innovative science that addresses critical health challenges. The authors also gratefully acknowledge additional support from the Cancer Research UK City of London Centre and the King’s Health Partners Centre for Translational Medicine, highlighting the collaborative ecosystem that fosters such significant breakthroughs.
Broader Implications and Future Horizons
The successful elucidation of MOv18 IgE’s mechanism of action represents a pivotal moment in oncology research. It not only provides a strong rationale for advancing MOv18 IgE through further clinical development but also opens new avenues for exploring other IgE-based antibodies. The unique ability of IgE to activate tissue-resident immune cells, particularly macrophages, holds immense potential for other solid tumours that are notoriously difficult to treat with current immunotherapies, such as pancreatic cancer, glioblastoma, and certain types of breast cancer – a prospect hinted at by the support from Breast Cancer Now.
The next crucial steps will involve Phase Ib and Phase II clinical trials. These trials will enroll larger patient cohorts, further evaluate the efficacy and safety of MOv18 IgE, optimize dosing regimens, and explore potential combination therapies with existing standard-of-care treatments or other immunotherapies. The ultimate goal is to translate these exciting findings into tangible improvements in patient outcomes, offering a new lease on life for those battling advanced ovarian cancer and potentially other challenging malignancies. The research from King’s College London stands as a beacon of hope, illustrating the power of innovative immunology to redefine the fight against cancer.
