Haematological and CAR-T Tumours: Cellular Signals That Predict the Future in the Nanoworld

Sixty minutes. Just one hour after CAR-T infusion is enough to understand if the patient is at risk of developing neurotoxicity in the following days. The credit for this breakthrough goes to biological structures only 100 nanometres in size—extracellular vesicles.

This is what emerged from a study led by researchers from the IRCCS Sant’Orsola Polyclinic and the University of Bologna, published in the “Journal of Clinical Investigation”. The researchers have discovered a method to predict the likely onset of ICANS—the neurotoxicity syndrome associated with immunoeffector cell therapy—several days in advance.

This syndrome is a side effect that affects approximately one-third of oncohaematological patients treated with CAR-T, an advanced cell therapy that uses the patient’s own T-lymphocytes (immune system cells) to fight haematological tumours, such as lymphomas and myelomas.

ICANS manifests 5-7 days after infusion, presenting with confusion, speech impairment, motor disorder, and seizures. In severe cases, it can progress to coma or death, making it one of the most serious complications of cell therapy.

The new study showed that a high concentration of extracellular vesicles in the blood, measured one hour after cell therapy infusion, is strongly correlated with the development of ICANS within the following week.

Predicting this complication in advance not only enables timely modulation of the therapeutic response but also helps shorten the duration of hospital stay. Currently, patients are hospitalised for about two weeks as a precautionary measure. Thanks to this breakthrough, those deemed not at risk can be safely discharged.

“This is an outstanding result, a significant step forward for a therapy that represents one of the most innovative and promising frontiers in the fight against myelomas and lymphomas”, explains Francesca Bonifazi, director of the Immunobiology of Transplantation and Cell Therapies Platform and the Transplantation and Cell Therapies Unit in Haematology of the IRCCS. “This study holds great value not only from a clinical point of view but also in the research field. It is a great step forward in understanding the pathogenesis of this complication”.

Extracellular vesicles are biological structures produced by all the cells of the human body and, in recent years, have been recognised as universal agents of intercellular and inter-organ communication. Essentially, they can be described as a sort of nano-shuttles that cells use to exchange information. Each vesicle contains a protein from its cell of origin and moves to its destination through extracellular fluids such as blood plasma.

Vesicles can move inside the human body, even covering long distances from their cell of origin. This makes them ideal candidates to study what happens within tissues that are otherwise not accessible unless through invasive techniques.

“During our research, we discovered that most of the extracellular vesicles of a CAR-T cell are produced when the cell encounters its target, the cancer cell”, explains Massimiliano Bonafè, Professor of General Pathology at the Department of Medical and Surgical Sciences of the University of Bologna and scientific advisor of the laboratory where the experiments were conducted. ‘At that point we asked ourselves: “Does the quantity of vesicles have a role in the development of ICANS?” In other words: "Is the value we detect predictive of a complication that occurs in the following days?”’

In both cases, the answer turned out to be yes. The study was conducted on a cohort of 100 patients who underwent CAR-T therapy for B-cell lymphoma and were followed by the department’s programme of diagnosis and therapies of lymphomas and chronic lymphoproliferative syndromes of the IRCCS Sant’Orsola Polyclinic, led by Pier Luigi Zinzani, Full Professor of Haematology at the University of Bologna and Director of the Haematology Unit of the Polyclinic. The results show that, in high levels, these vesicles are correlated with an increased likelihood of developing neurotoxicity.

Moreover, with the collaboration of Spartaco Santi, a researcher at the IGM-CNR Institute of Molecular Genetics of Bologna, the research reproduced an in vitro neuronal model to understand how increased vesicle production determines the development of the syndrome.

“We discovered that when vesicles interact with neurones of the central nervous system, they do not kill them (and are therefore not toxic) but rather stress them”, adds Massimiliano Bonafè. “This stress reaction can then be measured through additional vesicles produced by neurons”.

The study represents a great result for the Immunobiology of Transplantation and Cell Therapies Platform, established in 2022 to network the resources and skills of researchers from the IRCCS Sant’Orsola Polyclinic and the University of Bologna. It soon became a model to follow.

“We are a team of about fifteen biologists and haematologists” says Francesca Bonifazi. “Affiliated with either the IRCCS Sant'Orsola Polyclinic or the University of Bologna. Teamwork is required to achieve great results, and this study is proof of that. The first two signatures belong to Gianluca Storci and Francesco De Felice, an IRCCS medical researcher and a UNIBO PhD student”.