In a trial of a new treatment for aggressive lymphoma, known as CAR T cell treatment, 4 out of 10 patients were cancer-free 15 months after treatment[i]. The patients participating in the study had previously had chemotherapy, to which they did not respond. Though the follow-up period of this study is fairly short, the results have been described as a ‘significant step forward’ for lymphoma treatment[ii].
How It Works
The blood contains several types of white blood cells, including cells known as B cells and T cells. These cells are an important part of the immune system. CAR T cell treatment involves genetically modifying T cells so that they can both recognize and attack cancerous cells. Normal T cells are able to attack infected cells, but cannot tell the difference between cancerous cells and normal cells. Normal B cells are able to generate antibodies that can stick to the cancer cells, but cannot attack them. The engineered T cells have both the cancer-detecting properties of B cells and the killing ability of T cells. To create the modified cells, healthy T cells are taken from the patient’s blood and given genetic instructions to make cancer-seeking antibodies. They are then injected back into the patient[iii].
Most of the research into this technique has so far focused on blood cancers that develop from B-cells, including non-Hodgkin lymphoma, chronic lymphocytic leukaemia and lymphoblastic leukaemia. A protein known as CD19 is found on B-cells, and this is the target sought by the modified T cells. However, all B cells, whether healthy or cancerous, have this protein, and thus the modified T cells destroy healthy B cells as well as cancerous B cells[iv].
Results So Far
In the new study, 101 patients with large B cell lymphoma who did not respond to chemotherapy were treated with CAR T cells. After a median follow-up of 15.4 months, 40 % were cancer free, and after 18 months, 52 % were alive. The rates of response for this treatment are much higher than those for existing therapies for these diseases. There are hopes that other studies will achieve even higher response rates. The treatment is aggressive; every patient experienced some side effects. In an earlier study, 6 of 14 patients with large B cell lymphoma and 10 of 14 patients with follicular lymphoma (both are types of non-Hodgkin lymphoma) were cancer-free after 6 months. All patients in complete remission remained in remission at 7.7 to 37.9 months (median 29.3 months) after treatment. One patient died as a result of side effects[v].
Approval in the USA
In August, this treatment was approved by the FDA in the USA for the treatment of patients up to 25 years of age with a particular type of leukaemia, whose cancer has not responded or has returned after initial treatment[vi].
Blood Cancers in the UK
In the UK, in 2014 there were: 13,605 cases and 4,801 deaths from non-Hodgkin lymphoma[vii]; 9,534 cases and 4,584 deaths from leukaemia[viii]; 5,501 cases and 2,928 deaths from myeloma[ix]; and 2,106 cases and 355 deaths from Hodgkin lymphoma[x]. According to Cancer Research UK, 1 % of non-Hodgkin lymphoma cases are due to occupational exposures[xi]. All of the blood cancer types have been linked with various occupational exposures, including pesticides, though the results from studies are often unclear or conflicting at this stage. In the future, this treatment or similar treatment may become more widely used in blood cancer patients, and may appear on claims if the scientific evidence of links with occupational exposures become better known and understood.
[i] Neelapu, S. S. et al. Axicabtagene Ciloleucel CAR T-Cell Therapy in Refractory Large B-Cell Lymphoma. N. Engl. J. Med. (2017). doi:10.1056/NEJMoa1707447 http://www.nejm.org/doi/full/10.1056/NEJMoa1707447#t=article (Accessed 27 December 2017)
[ii] Immune cell therapy results are ‘landmark moment’ in lymphoma treatment. Cancer Research UK. 12 December 2017. http://www.cancerresearchuk.org/about-us/cancer-news/news-report/2017-12-12-immune-cell-therapy-results-are-landmark-moment-in-lymphoma-treatment (Accessed 27 December 2017)
[iii] CAR T cells: Engineering a cancer-fighting immune super soldier. Cancer Research UK: Science Blog. 19 January 2016 http://scienceblog.cancerresearchuk.org/2016/01/19/engineering-a-cancer-fighting-immune-super-soldier/?_ga=2.59157677.1420617261.1514331038-1957833694.1488527976 (Accessed 27 December 2017)
[v] Schuster, S. J. et al. Chimeric Antigen Receptor T Cells in Refractory B-Cell Lymphomas. N. Engl. J. Med. (2017). doi:10.1056/NEJMoa1708566 http://www.nejm.org/doi/full/10.1056/NEJMoa1708566#t=article
[vi] FDA approval bring first gene therapy to the United States. FDA News Release 30 August 2017. https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm574058.htm (Accessed 27 November 2017)
[vii] Non-Hodgkin lymphoma statistics Cancer Research UK http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/non-hodgkin-lymphoma (Accessed 27 December 2017)
[viii] Leukaemia (all subtypes combined) statistics Cancer Research UK http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/leukaemia (Accessed 27 December 2017)
[ix] Myeloma statistics Cancer Research UK http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/myeloma (Accessed 27 December 2017)
[x] Hodgkin lymphoma statistics Cancer Research UK http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/hodgkin-lymphoma (Accessed 27 December 2017)
[xi] Non-Hodgkin lymphoma risk factors Cancer Research UK http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/non-hodgkin-lymphoma/risk-factors (Accessed 27 December 2017)