It’s the Holy Grail of medical science – a cure for cancer. And if the results published in Nature this month are anything to go by, we’re one step closer. In fact, for some types of cancer, we may already be there.
Dr J. Joseph Melenhorst and more than 30 other authors have written an article titled, “Decade-long leukaemia remissions with persistence of CD4⁺ CAR T-cells”. In that technical article is a revelation – cancer patients given a new type of therapy 10 years ago still have cancer-killing cells and are cancer free.
That sounds extremely encouraging, but it should be pointed out that article focuses on only two patients. The pair suffered from chronic lymphocytic leukaemia (CLL), and were infused with ‘CTL019’ cells in 2010 as part of a phase one trial. Both had complete remissions and a persistence of the infused CAR T-cells.
More than a decade later, both patients remain in remission. One, David Olson, took up running half-marathons in the years after his treatment. Now aged 75, Mr Olson said he retired from running half-marathons only in 2018. Describing his recovery, the Californian resident said: “This is a cure. And they don’t use the word lightly.”
What are CAR T-cells?
A T-cell, also known as T lymphocyte, is a white blood cell that is an essential part of our immune system. They originate in bone marrow, and institutes such as the Peter McCallum Cancer Centre in Melbourne collect and re-engineer them to carry special structures called chimeric antigen receptors (CARs) on their surface.
When these CAR T-cells are reinjected into a patient, they multiply rapidly and the engineered receptors may help the T-cells identify and attack cancer cells.
Are CAR T-cells the future of cancer treatment?
The signs are certainly good for those who may be diagnosed with leukaemia or lymphoma, and perhaps further down the track for those with ‘solid cancers’. A solid cancer is defined as an abnormal cellular growth in a solid organ such as the breast or prostate, as opposed to leukemia, a cancer affecting the blood, which is liquid.
The hurdle in treating solid cancers is a type of sugar that coats many solid cancers. A group of Italian scientists has found that sugar-based structures called N-glycans, which are expressed on the surface of pancreatic tumour cells, could protect the cancer from CAR T-cells.
The scientists, from IRCCS San Raffaele Scientific Institute, observed that disruption of the coating with a sugar analog dubbed 2DG enhanced CAR-T killing in different mouse models of pancreatic tumours and showed promise against other cancers in lab dishes.
So, do we have a ‘cure’ for cancer?
With increasing cancer survival rates, the word ‘cure’ is gaining agency, and one Mr Olson happily uses to describe his condition. But it is one that is still the subject of debate.
A paper published by the US National Center for Biotechnology Information several years ago, proposes that the appropriateness of using the word ‘cured’ relates to scientific evidence, and perception by cancer patients of terms such as ‘chronic’, ‘survivor’ and ‘cured’. Some oncologists prefer to use the term ‘long-term survivor’ instead of ‘cured’. Some practitioners believe a ‘cure’ is impossible in some settings.
The debate will continue for some time yet, but regardless of the preferred word the advances in cancer treatment continue apace, and there is good reason for optimism.
Have you experienced T-cell cancer therapy? Or have you had other forms of cancer treatment? Why not share your experience in the comments section below?
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