Scientists have made significant strides in harnessing the body's immune cells to treat liquid tumors, but solid tumors have proven more challenging. A recent study from Stanford Medicine researchers and collaborators introduces a novel cell therapy approach that could revolutionize the treatment of solid tumors. The focus is on supercharging natural killer cells, a type of immune cell, to create tissue-resident natural killer cells that can effectively infiltrate and kill solid tumor cells.
The study's lead authors, John Sunwoo, Nina Horowitz, Imran Mohammad, and June Ho Shin, discovered a method to transform natural killer cells into a specialized form that can reside within tissues and exhibit enhanced tumor-killing capabilities. These tissue-resident natural killer cells demonstrated superior performance compared to conventional natural killer cells in infiltrating solid tumors, a finding that was both reproducible and striking.
The researchers tested this therapy in mice and observed that the specialized natural killer cells significantly slowed the growth of various solid tumors. When combined with an antibody treatment, cetuximab, the therapy further reduced tumor growth. Importantly, natural killer cells do not elicit an immune reaction when transferred between individuals, making this therapy potentially scalable and accessible to a wide range of patients.
The study also delves into the contradictory evidence surrounding tissue-resident natural killer cells. Some studies suggest they are sluggish killers and even immunosuppressive, while others highlight their efficiency. The researchers identified two distinct types of tissue-resident natural killer cells, each with unique functions and development requirements. They found that TGF-b, a signaling protein, plays a crucial role in their differentiation, but the amount and manner of TGF-b presentation are critical for their effectiveness.
The team's breakthrough recipe for supercharging natural killer cells involves exposing them to short-lived human epithelial tumor cells, which present a fleeting amount of active TGF-b. This approach results in highly efficient killers, as direct contact with the epithelial tumor cells is essential for activation. The researchers also identified specific surface proteins and tools used by these cells, such as CD39 and perforin, which contribute to their tumor-killing capabilities.
The study's findings have significant implications for tumor treatment. The combination of supercharged natural killer cells and cetuximab showed promising results in suppressing tumors in mice. The researchers are now planning a Phase I clinical trial to test this combination therapy in patients with advanced squamous cell carcinoma. Additionally, the recipe for transforming natural killer cells has been patented, allowing for the production of a scalable and accessible cell therapy.
In conclusion, this study represents a significant advancement in the field of cancer immunotherapy. The development of tissue-resident natural killer cells that can effectively infiltrate and kill solid tumors offers a promising approach to treating this challenging type of cancer. The potential for an off-the-shelf, scalable therapy is particularly exciting, as it could revolutionize the accessibility and effectiveness of cell therapy in cancer treatment.
