Until recently, it was believed that the innate immune system, the body's first line of defense, lacked the ability to remember pathogens like the adaptive immune system. A ground-breaking study introduces a 'nanobiologic' immunotherapy that can train the innate immune system and help it to eliminate tumorous cells. The new approach has been successfully demonstrated in a mouse melanoma model.

Immunotherapy has received plenty of attention in cancer therapy in recent years. The treatment involves activating lymphocytes - immune cells produced by the body - to fight tumorous cells.

Our immune system consists of two parts; the innate immune system and the adaptive immune system. The former provides an initial rapid response to an infection and mobilizes the latter through antigens associated with a detected pathogen. Our adaptive immune system can acquire immunological memory against pathogens naturally or via vaccination. As a result, it can produce the necessary immunity response to eliminate previously encountered pathogens.

It was long believed that the innate immune system lacked memory. However, the pioneering work has demonstrated that the innate immune system can be "trained", for example by vaccinating individuals with the BCG vaccine against tuberculosis. They showed that innate immune cells can acquire a primitive memory through metabolic and epigenetic rewiring, which elevates cell responsiveness.

Essentially, production of innate immune cells with a trained immunity phenotype is regulated by progenitor cells in bone marrow, which are the cells that can differentiate into suitably programmed immune cells.

For cancer therapy, therapeutic targeting of trained immunity could be hugely beneficial. The results of an extensive collaborative effort has been published in the prestigious journal Cell.

"The work involves the development and preclinical evaluation of a novel immunotherapy based on highly biocompatible nanomaterials called nanobiologics. Our study is a significant advancement for both trained immunity and cancer treatment, with real translational potential," says the author.

The researchers created a library and after extensive screening, they identified a nanobiologic lead candidate that effectively induced trained immunity and displayed high bone marrow propensity. Next, the researchers administered the nanobiologic therapeutic intravenously to a mouse melanoma model. The induction of trained immunity response led to myelopoiesis, the production of trained myeloid cells in the bone marrow.

Importantly, the trained myeloid cells changed the tumor microenvironment allowing immune cells to effectively combat the cancerous cells. Findings from the research demonstrate that this approach could be used as a stand-alone anti-cancer therapy or in conjunction with checkpoint inhibitor drugs, a clinical cancer immunotherapy. Importantly, nanobiologic immunotherapy displayed similar characteristics in non-human primates and was found to exhibit a favorable safety profile.

The biotech startup Trained Therapeutix Discovery (TTxD) is working on the further development of the nanobiologic treatment to address some of the most recalcitrant and debilitating diseases including cancer and serious infection. TTxD aims to transition the treatment to Phase I clinical human trials within two to four years.

https://www.cell.com/cell/fulltext/S0092-8674(20)31300-3