Unleashing the Power of Listeria: A Revolutionary Approach to Cancer Immunity
For nearly four decades, scientists have been studying the cunning ways Listeria bacteria manipulate our bodies, leading to the potentially deadly disease listeriosis. However, a groundbreaking discovery by Daniel Portnoy and his team has turned this bacterial villain into a potential hero in the fight against cancer.
Three years ago, Portnoy co-founded Laguna Biotherapeutics, a startup with a mission to harness the unique properties of Listeria. They aimed to create a therapy that could boost the immune system's natural defenses against cancer, and their efforts have led to an exciting development.
Laguna Bio is set to approach the FDA with a therapy designed for children with leukemia who have undergone bone marrow transplants. The goal? To enhance the production of gamma delta T cells, the body's general-purpose cancer cell killers, and provide a powerful defense mechanism for these young patients.
But here's where it gets controversial... Portnoy and his colleagues believe this Listeria-based therapy has the potential to go beyond cancer. It could be a game-changer for various diseases, including multiple myeloma, lymphomas, and even infectious diseases like malaria and tuberculosis. The therapy stimulates the body's innate immune system, targeting any compromised cell, which sets it apart from traditional cancer immunotherapies that focus on the adaptive immune system.
"The immune system is often suppressed in tumor environments," Portnoy explains. "Listeria, seen as a foreign invader, induces an innate immune response, helping the body overcome this suppression."
Last year, Portnoy and his team published their successful trials in mice, showcasing the potential of this attenuated Listeria therapy. They also reported on another exciting development: Listeria can be engineered to boost mucosal-associated invariant T cells (MAIT), further enhancing the body's defense mechanisms.
Jonathan Kotula, CEO of Laguna Bio, emphasizes the decades of research behind this approach, particularly Portnoy's work, which has led to a comprehensive understanding of Listeria's unique immune response. "Attenuated Listeria seems to carefully orchestrate the entire immune system, generating a robust response," he adds.
The key to this therapy lies in Listeria's ability to escape the phagosome, a digestive organelle within scavenger cells called phagocytes. Portnoy's early research showed that Listeria can evade digestion and set up camp inside cells, hiding from the immune system until it's ready to reproduce and spread. This unique behavior forms the basis of their innovative therapy.
Portnoy's journey with Listeria began with a collaboration with Aduro Biotech in the 2000s. They engineered Listeria to express cancer antigens, aiming to induce the adaptive immune system to target specific tumors. While this therapy, known as LADD, showed promise in mice, it didn't translate as effectively in human trials. However, an observation during these trials sparked a new idea: Listeria's ability to induce T cells of the innate immune system, not just cytotoxic T cells.
The Laguna Bio therapy, an improved version of LADD, takes this concept further. By deleting two additional genes, they've created a strain called QUAIL (Quadruple Attenuated Intracellular Listeria), making it even safer for human use. QUAIL lacks enzymes required to synthesize essential nutrient cofactors derived from riboflavin (vitamin B2), which are readily available inside cells but not outside. This modification restricts QUAIL's growth to the intracellular environment, making it a safer and more controlled therapy.
"QUAIL fits the criteria we were looking for - a mutant Listeria that can grow inside cells but not outside," Portnoy says. "It's a safer strain, and we're excited about its potential."
The newly published study confirms QUAIL's safety and potency in mice, and its inability to grow outside cells sets it apart from LADD. This means QUAIL cannot grow on ports and implants often used in cancer treatment, adding an extra layer of safety.
Human trials with LADD revealed its ability to induce gamma delta T cells of the innate immune system, even if it didn't boost cytotoxic T cells as effectively. Since then, research has shown that gamma delta T cells can directly attack and kill cancer cells and produce cytokines that activate other immune cells. QUAIL has the potential to enhance these gamma delta T cells, providing a powerful immune response.
Kotula believes the data from previous human trials with LADD provides a robust foundation for their new approach. "It's a unique plan, informed by human data, and we're confident in its potential," he says.
In initial trials with pediatric leukemia patients, Laguna Bio plans to use QUAIL directly to stimulate a gamma delta T cell response. The goal is to provide a robust defense against infection, rejection, and cancer recurrence, especially in patients where the adaptive immune system has been suppressed to prevent transplant rejection.
If QUAIL proves successful in Stanford's trials, Kotula envisions a broader application, treating various cancers and even using it prophylactically as a vaccine against infectious diseases. "Let's reinvigorate the immune system, focusing on cancers where gamma delta T cells have shown promise. Once we have that reinvigoration, we can direct it to specific targets."
This innovative therapy has the potential to revolutionize cancer treatment and offer new hope for patients. It's an exciting development that showcases the power of scientific research and the potential for bacterial pathogens to become powerful allies in the fight against disease.
What do you think about this unique approach to cancer immunity? Could Listeria be the key to unlocking a new era of immunotherapy? Share your thoughts in the comments!
