The initial clinical phase of a treatment that trains human defense cells to better combat hematological cancer — more specifically, B acute lymphocytic leukemia and B non-Hodgkin lymphoma — was authorized by Anvisa (National Health Surveillance Agency).
The research developed by Fundherp (Fundação Hemocentro de Ribeirão Preto) in partnership with the Butantan Institute will use so-called CAR-T cells to seek remission of the hematological cancers mentioned above in “relapsed and refractory” patients (that is, in cases of reappearance of the disease or resistance to standard treatment)”, says Anvisa in a note.
The acronym CAR-T corresponds to the expression “chimeric T cell antigen receptors”. T cells are already naturally responsible for attacking and killing cancer cells, as well as attracting other cells to go on the offensive.
For training, the patient’s defense cells are collected and, after genetic modifications to them, they are reintroduced into the person. The training in question involves a virus that, functioning as a kind of Trojan horse, takes genes of interest to the patient’s T lymphocytes — thus making the aforementioned genetic modification.
According to Anvisa, the approval is part of a collaboration project to promote advanced therapies available in the SUS (Unified Health System). Fundherp and Butantan were selected from a public notice earlier this year.
Anvisa claims to have a follow-up plan until 2024 to monitor the development of the treatment. “If the results are good, the objective is to register the product quickly so that people have access to a safe, effective and high-quality treatment option available in the SUS”, says the regulatory agency in a note.
The agency also says that, since 2020, three CAR-T therapy products have been registered in the country, aimed at treating leukemias, lymphomas and myelomas. There were also two registrations for the treatment of rare genetic diseases.
Anvisa states that, at the moment, there are more than 40 clinical trials related to advanced therapies, such as CAR-T, in progress.
How was the first test in Brazil
The first national test took place at USP in Ribeirão Preto, in 2019. The treatment was carried out on retired Minas Gerais native Vamberto Luiz de Castro, 62, resident of Belo Horizonte, diagnosed with B-cell non-Hodgkin lymphoma.
The miner had been considered a terminal patient and suffered from severe pain and weight loss.
It is worth noting that, in this case, it was not a traditional clinical trial, with numerous volunteers and aimed at testing the safety of a therapy. The test fell under the so-called compassionate use.
In any case, the results in Castro attracted attention, with symptoms disappearing and blood tests returning to normal.
However, a few months after using the therapy, Castro died in a domestic accident, a fall that caused severe head trauma.
How does CAR-T cell therapy work?
CAR-T cells are immune system cells (known as T lymphocytes) extracted from the patient. They are genetically modified to recognize and attack tumor cells and then reintroduced into the patient. Thus, they become more effective in identifying the cancer focus and attacking it.
The technique derives from studies on cell therapy, which began in the 1950s with bone marrow transplantation. Similarly, CAR-T therapy consists of “transplanting” the patient’s modified immune system in order to help with the immune response. Additionally, CAR-T cells carry information about the target to be attacked, in this case tumor cells.
Experimental CAR-T therapy uses the patient’s own cells, but there is research with modified cells from donors (called “allo-CAR-T”, derived from “other”). At the moment, there is no authorization for the use of donor cells in Brazil.
In general, patients with very aggressive cancer, or who have some weakening of the immune system, have greater difficulty generating their own immune response, which is why CAR-T therapy can be an important ally.
Because the therapy is only used for so-called compassionate use, when no other treatment is available, responses are often varied.
For which types of cancer is it recommended?
Currently, CAR-T therapy has been successful in treating some types of cancer of the blood system, such as lymphomas, leukemias and myelomas, but there is no proof of effectiveness against solid tumors. In these cases, chemotherapy, radiotherapy or treatments such as immunotherapy tend to have more effect.