The first gene therapy with CAR T cells capable of treating – with a good probability of success – the most serious forms of neuroblastoma, the most frequent solid tumor in childhood, has been designed at the Bambino Gesù Children’s Hospital. The new treatment, developed by the team of clinicians and researchers led by prof. Franco Locatelli, was tested on 27 children with relapsed neuroblastoma and/or resistant to conventional therapies.

The response to treatment has exceeded 60% and the probability of surviving without disease is significantly increased compared to the unfortunately short life expectancy in the absence of other treatments. The results of the study, also carried out thanks to funding received from AIRC, the Ministry of Health, AIFA and the Italian Foundation for the Fight against Neuroblastoma, have just been published in the prestigious New England Journal of Medicine.

Neuroblastoma is the most frequent extra cranial solid tumor in childhood and accounts for about 7-10% of tumors in children aged 0-5 years. In Italy, about 120-130 new diagnoses are made each year. This tumor originates from neuroblasts, cells present in the sympathetic nervous system, and can arise in different parts of the body, the most frequent of which is the adrenal gland.

Even today, neuroblastoma has a significantly less good prognosis than other childhood neoplasms, being responsible for 11% of childhood cancer deaths: in metastatic forms or with a high risk of recurrence, the probability of definitive healing is 45-50%; in case of relapse or disease refractory to conventional treatments (chemo and radiotherapy), the possibility of surviving 2 years does not exceed 5-10%. 

The experimentation of gene therapy with CAR T cells directed against neuroblastoma was entirely designed and conducted by doctors and researchers of the Bambino Gesù Children’s Hospital coordinated by prof. Franco Locatelli. The study involved the Pharmaceutical Workshop, the areas of Oncohematology, Cell Therapy, Gene Therapies and Hematopoietic Transplantation and Diagnostic Imaging. 

Between 2018 and 2021, 27 patients from all over Italy, aged between 1 and 25 years, affected by relapsed and/or resistant neuroblastoma and already subjected to numerous treatment attempts, were enrolled in the trial, with the aim of “verifying if CAR T cell therapy was able to change the natural history of their disease” explains prof. Franco Locatelli, head of the research area and clinical area of Oncohematology, Cell Therapy, Gene Therapies and Hematopoietic Transplantation of Bambino Gesù, as well as Full Professor of Pediatrics at the Catholic University of the Sacred Heart.

The patients involved in the study were treated with the infusion of CAR T cells modified with a third generation construct, called GD2-CART01, produced in the laboratory by researchers of the Holy See Hospital starting from the collection of autologous T lymphocytes (i.e. coming from the patient himself).

These cells of the immune system were then genetically modified to express CAR (Chimeric Antigen Receptor) on their surface, a synthetic molecule capable of recognizing the tumor target (in neuroblastoma it is the GD2 molecule) and directing T lymphocytes against the diseased cells.

Unlike the second generation CAR T products approved today for clinical use in leukaemia, lymphoma and myeloma, the drug designed by the Bambino Gesù researchers was added, on the basis of the results of an accurate and meticulous pre-clinical experimental work, a second costimulatory domain, i.e. a combination of molecules that increases the efficacy and persistence of engineered T lymphocytes.

Finally, as a further safety measure of the therapy, the suicide gene (Inducible Caspase 9 or iC9) was inserted, which blocks the action of the modified T lymphocytes in the event of undesirable effects that cannot be controlled with conventional pharmacological measures.

The experimentation on the 27 patients enrolled in the study was conducted in two phases: in phase 1 the safety and tolerability of the drug were evaluated according to a model of increasing doses (in the absence of toxicity) or decreasing doses (in the event of toxicity).

CAR T infusions started from the intermediate dose (the third of 5) up to the maximum dose as no relevant side effects were found. In phase 2, the efficacy of the therapy and the residence times in the body of genetically modified cells were evaluated.

The new CAR T cell therapy for relapsed and/or refractory neuroblastoma has been shown to be safe and effective: at the end of the study, the Bambino Gesù research team observed a response to the treatment in 63% of the patients, half of whom were in complete remission of the disease.

The probability of survival up to 3 years (60% of cases) and of surviving without evidence of disease (36%) increases. The longevity of CAR T cells has also been documented: they persist in the patient’s body up to 2-3 years after the infusion, supporting the therapeutic efficacy over time. 

“It is the first time at an international level that a study on the use of CAR T cells against solid tumors has achieved such encouraging results and on such a large case series” emphasizes prof. Franco Locatelli, coordinator of the experimentation. “We finally have one more therapeutic weapon that can be used to treat children diagnosed with neuroblastoma”.

The results of the Bambino Gesù experimentation open up the possibility, in perspective, of the anticipated use of CAR T cells in the therapeutic strategy of children with neuroblastoma: a cure intended, therefore, not only for patients who have already failed several treatment attempts, but also for those newly diagnosed with high-risk characteristics or for those who have failed only one line of therapy. Furthermore, this study constitutes clear evidence of the efficacy of CAR T cells also in solid tumors, opening up possible treatment scenarios also for other solid tumors.

Furthermore, to further enhance the effectiveness of CAR T immunotherapy against neuroblastoma, prof. Concetta Quintarelli and dr. Francesca Del Bufalo claimed, “we will try to simultaneously attack a population of cells of the immune system called MDSCs (myeloid derived suppressor cells) which inhibit the anti-tumor action mediated by T lymphocytes. In fact, we have evidence that the higher the number of MDSCs, the lower the effectiveness of CAR T cells. It is therefore reasonable to hypothesize that there is a benefit to simultaneously infusing CAR cells and using drugs that eliminate MDSCs”.

The launch of an experimentation extended to other European centers is currently being studied to replicate the results of the Bambino Gesù trial on neuroblastoma on an ever larger scale. The same type of CAR T cells directed against the GD2 target molecule will also be used in pediatric and young adult patients suffering from various types of brain tumors in a trial that will begin shortly.

“The results of this study – comments prof. Franco Locatelli – represent the culmination of a project, started many years ago, aimed at offering a therapeutic response to those children with neuroblastoma who have limited prospects for recovery and document how treatment with CAR T cells can significantly change the treatment scenario even in solid tumors”.

“Today we are giving back to the community a concrete example of the impact that scientific research of excellence has on the care of small cancer patients – declares prof. Federico Caligaris Cappio, scientific director of the AIRC Foundation – We are proud to have contributed to this important milestone achieved at the Bambino Gesù Children’s Hospital by the group of professor Franco Locatelli, owner of a project included in the AIRC 5 per thousand special programs, created with the aim of bringing tangible benefits to patients as quickly as possible through the creation of a network of centers of excellence from laboratories to treatment centers.

An ambitious goal that the AIRC Foundation can achieve thanks to the trust of millions of citizens who choose to give continuity to cancer research with the signatures of 5 per thousand”.

Sara Costa, president of the Italian Association for the Fight against Neuroblastoma: “A bet that began 9 years ago, in 2014, due to the still too high number of children suffering from Neuroblastoma and refractory to treatment and the burning desire of us parents to have effective answers in a short time.

At the time, the path of gene therapy in the pediatric field, for such aggressive tumors, seemed far away. Yet the project of arriving at an innovative clinical experimentation widened my heart, allowing us to glimpse a light on the horizon. Today, 9 years later, the emotion of this day is indescribable. The results are extraordinary, but we still have to continue until all children with Neuroblastoma can recover”.

“CAR T cells – comments prof. Ruggero De Maria, president of the Alliance Against Cancer – are revolutionizing the therapies of hematological neoplasms; this extraordinary study coordinated by prof. Locatelli demonstrates that CAR T cells could effectively treat solid tumors as well. It is an important success to which the Alliance Against Cancer program has also contributed, which has produced excellent results and which I hope will continue to be funded as in the past”. 

“These extraordinary results – claims prof. Tiziano Onesti, president of Bambino Gesù – once again confirm how important research is for the Hospital and above all for the families who come to us”. As the Holy Father reiterated in the audience for our 150th anniversary: “There is no cure without research. And there is no future in medicine without research”.

“Yet we know that research costs money, – adds prof. Onesti – and requires huge investments, especially research into advanced therapies, which represent a challenge, also in terms of sustainability, for the national health system and for the same health structures like ours. But it is a challenge that we absolutely must overcome, for the good of the patients, and we must all overcome it together”.