By Lina carolina 
A groundbreaking study spearheaded by researchers at Keck Medicine of USC has unveiled a potent new combination therapy that demonstrates remarkable potential in extending survival for patients diagnosed with glioblastoma, an aggressive and notoriously difficult-to-treat brain tumor. This innovative approach integrates Tumor Treating Fields therapy (TTFields) with immunotherapy and chemotherapy, offering a beacon of hope for individuals facing a diagnosis with a historically grim prognosis. According to the National Brain Tumor Society, the average survival rate for glioblastoma patients hovers around a mere eight months, underscoring the urgent need for more effective treatment modalities.
Unlocking Immunotherapy’s Potential in Glioblastoma Treatment
The core of this groundbreaking research lies in the synergistic effect of combining TTFields with existing treatments. Tumor Treating Fields therapy, a non-invasive treatment that utilizes targeted low-intensity electric fields, has shown promise in disrupting tumor cell growth by interfering with their ability to divide. This therapy works by delivering alternating electric fields that oscillate key cellular structures within cancer cells, effectively making it challenging for them to multiply. When applied to glioblastoma, TTFields are delivered via a specially designed cap with mesh electrodes placed on the scalp, generating electric fields precisely tuned to the tumor’s location and characteristics. Patients typically wear this device for approximately 18 hours a day, a commitment that appears to yield significant benefits when integrated with other therapies.
The study’s findings suggest that TTFields play a crucial role in "priming" the tumor microenvironment, making it more receptive to the body’s own immune system and to immunotherapy. Researchers observed a significant increase in tumor-fighting T cells, a vital component of the immune system responsible for identifying and neutralizing cancer cells, within and around the glioblastoma tumors of patients receiving TTFields. Crucially, when this T cell infiltration is followed by immunotherapy, these T cells appear to remain active for longer durations and are replenished by even more robust and effective tumor-fighting T cells.
Dr. David Tran, MD, PhD, chief of neuro-oncology at Keck Medicine, co-director of the USC Brain Tumor Center, and the study’s corresponding author, eloquently described this phenomenon. "By using TTFields with immunotherapy, we prime the body to mount an attack on the cancer, which enables the immunotherapy to have a meaningful effect in ways that it could not before," he stated. "Our findings suggest that TTFields may be the key to unlocking the value of immunotherapy in treating glioblastoma." This statement highlights the transformative potential of TTFields in overcoming the inherent challenges of treating this aggressive brain cancer.
While TTFields are often used in conjunction with chemotherapy, the prognosis for glioblastoma has remained poor even with these aggressive standard treatments. Similarly, immunotherapy, a powerful tool in treating many other cancers, has historically shown limited efficacy when used as a standalone treatment for glioblastoma. This new research, however, points towards a paradigm shift by demonstrating that the addition of immunotherapy to the TTFields and chemotherapy regimen can significantly enhance survival outcomes.
A Significant Leap in Survival Rates
The most compelling outcome of this study is the reported 70% increase in overall survival among patients who received the triple combination therapy compared to historical data or control groups. This represents a substantial improvement in a disease where incremental gains are hard-won. Furthermore, the study revealed particularly encouraging results for patients with larger, unresected (meaning not surgically removed) glioblastoma tumors. These patients exhibited an even stronger immune response to the TTFields and consequently lived even longer. This observation suggests that a larger tumor burden might, paradoxically, provide more targets for the therapy to engage the immune system, thereby amplifying its effectiveness.
The Science Behind the Synergy: Overcoming the Blood-Brain Barrier
The immunotherapy agent used in this study, pembrolizumab, is an immune checkpoint inhibitor (ICI). ICIs work by releasing the brakes on the immune system, allowing T cells to more effectively recognize and attack cancer cells. However, a significant hurdle in treating brain tumors like glioblastoma is the presence of the blood-brain barrier (BBB). This highly selective physiological barrier protects the brain by tightly controlling the passage of substances from the bloodstream into brain tissue. While essential for neurological health, the BBB can also impede the entry of T cells and therapeutic agents into the brain, creating an immunosuppressive environment that shields glioblastomas from the body’s natural immune defenses.
This inherent immunosuppression within and around glioblastomas significantly diminishes the effectiveness of treatments like pembrolizumab and chemotherapy when used alone. Dr. Tran’s hypothesis, which has now been substantially supported by this research, was that the most effective strategy to overcome this challenge would be to initiate an immune reaction directly within the tumor itself. This approach, known as in situ immunization, is precisely what TTFields appear to achieve. By activating the immune system at the tumor site, TTFields create an environment where immunotherapy can then amplify this response, bolstering the body’s own defense mechanisms against the cancer.
Dr. Tran further elaborated on this concept using a sports analogy: "Think of it like a team sport — immunotherapy sends players in to attack the tumor (the offense), while TTFields weaken the tumor’s ability to fight back (the defense). And just like in team sports, the best defense is a good offense." This analogy effectively conveys how TTFields and immunotherapy work in concert to create a more formidable assault on the glioblastoma.
Study Design and Key Findings
The research analyzed data from the 2-THE-TOP Phase 2 clinical trial, which enrolled 31 patients newly diagnosed with glioblastoma who had already completed chemoradiation therapy. Out of these participants, 26 were treated with TTFields in combination with both chemotherapy and immunotherapy. A particularly vulnerable subgroup within this cohort consisted of seven patients whose tumors were deemed inoperable due to their location. These individuals, representing a high-risk group with a particularly poor prognosis and limited treatment options, were also included in the study.
Patients in the trial received between six and 12 monthly cycles of chemotherapy, administered concurrently with TTFields for a duration of up to 24 months. The number and duration of these treatments were tailored based on each patient’s individual response. Immunotherapy was administered every three weeks, commencing with the second dose of chemotherapy, and continued for a maximum of 24 months.
The results from this trial were striking. Patients who utilized the TTFields device alongside chemotherapy and immunotherapy experienced an approximate 10-month increase in survival compared to historical control groups who had received the device with chemotherapy alone. This improvement is significant in itself, but the data for patients with large, inoperable tumors was even more profound. These individuals lived approximately 13 months longer and demonstrated markedly stronger immune activation in comparison to patients who had undergone surgical removal of their tumors.
"Further studies are needed to determine the optimal role of surgery in this setting, but these findings may offer hope, particularly for glioblastoma patients who do not have surgery as an option," Dr. Tran emphasized. This statement acknowledges the ongoing debate about the role of surgery in glioblastoma treatment and highlights the potential of this new combination therapy for patients who are not candidates for surgical intervention.
The Path Forward: Advancing Research to Clinical Practice
Building on these promising results, Keck Medicine is actively participating in a multicenter Phase 3 clinical trial. This larger-scale study aims to definitively validate the efficacy of the TTFields, immunotherapy, and chemotherapy combination in a broader patient population. Dr. Tran, who has dedicated over a decade to researching TTFields, is serving as the chair of the steering committee for this pivotal trial. Dr. Frances Chow, a neuro-oncologist at USC Norris, is the principal investigator for the Keck Medicine site.
This Phase 3 trial is a substantial undertaking, currently enrolling patients at 28 sites across the United States, Europe, and Israel. The trial is designed to recruit over 740 patients by April 2029. A key aspect of this study is its inclusion of patients with varying degrees of tumor resection – including gross total resection, partial resection, or biopsy-only tumors. This will allow researchers to meticulously assess how the extent of surgical tumor removal influences the immune response to the novel combination therapy.
The research team responsible for this significant advancement includes Dongjiang Chen, PhD, assistant professor of research neurological surgery; Son Le, PhD, assistant professor of research neurological surgery; Harshit Manektalia, research programmer; Ming Li, PhD, professor of research population and public health sciences; and Adam O’Dell, research lab specialist, all from the Keck School of Medicine of USC. Contributions were also made by Ashley Ghiaseddin, MD, and Maryam Rahman, MD, MS, colleagues from the University of Florida.
The funding for this crucial study was provided by a grant from Novocure, the manufacturer of the Optune device, which delivers the TTFields therapy. Dr. Tran has also received honoraria from Novocure for his consultant work, and both he and Dr. Chen are listed as inventors on patent applications related to the work presented in this study.
Broader Implications and Future Directions
The implications of this research are profound. Glioblastoma has long been a formidable challenge in oncology, characterized by its rapid growth, invasive nature, and resistance to conventional treatments. The limited success of immunotherapy as a standalone therapy for this cancer has been a significant area of investigation. This study offers a potential breakthrough by demonstrating how TTFields can act as a catalyst, essentially "awakening" the immune system and making it receptive to immunotherapy.
The success of this combination therapy, particularly in patients with unresectable tumors, could dramatically alter the treatment landscape for a significant portion of glioblastoma patients who currently have very few viable options. The ability to harness the body’s own immune system in a more effective manner, facilitated by TTFields, represents a major step forward in precision oncology.
The ongoing Phase 3 trial is critical in confirming these findings on a larger scale and establishing this combination therapy as a new standard of care. The detailed analysis of how tumor resection influences immune response will also provide valuable insights into optimizing treatment strategies for individual patients. As research continues, the hope is that this innovative approach will not only extend survival but also improve the quality of life for glioblastoma patients, offering a much-needed ray of optimism in the fight against this devastating disease.