Saturday, 31 May 2014

Fighting fire with fire - Part 2 (Cancer with HIV)

The second instalment in this three-part series will focus on the use of HIV as treatment for cancer. The cure for cancer has been sought after for many years, and new developments every day take us closer to the elusive goal! One of the most prominent recent studies is the work of Professor Carl H. June (MD, of the University of Pennsylvania) and his team.

In order to appreciate this potential treatment, let’s first look at how both cancer and HIV work.

Cancer is a condition in which cells in a specific part of the body grow and reproduce uncontrollably. These cancerous cells can begin in one area and spread to other areas of the body (also known as metastasis), and destroy healthy tissue along the way. The most prevalent types of cancer include breast, bowel, prostate, lung, bladder and uterine. Cancer itself is not uncommon, and statistically more than 1 in 3 people will develop some form of it during their lifetime. However, research into cancer receives a lot of funding (perhaps partially due to the vast numbers of people it affects) and so exciting new developments are rife. It is important to realise that although the elusive “magic pill” cure for cancer has not been found, other aspects of the condition such as treatment methods and palliative care have improved dramatically. This is demonstrated by the fact that survival rates of those with cancer have doubled in the UK over the last 40 years.

Cancer cells are fundamentally different from the cells that make up our bodies, but they begin life as normal cells. Usually, throughout the cycle of a cell's “life”, the cell will grow and can reproduce, and when it becomes old or damaged it will die (by a process known as apoptosis) and is replaced with new ones. However, in the case of cancerous cells, some of the genetic information (DNA) may be mutated or damaged, and result in the cell reproducing continuously and not dying. The cell is essentially immortal, and these cells can then clump together and form a mass of tissue, also known as a tumour.

Currently, the route to treating cancer involves use of chemotherapy and radiotherapy. These involve cancer-killing medication and use of x-rays respectively, but as both methods are extremely powerful they can also have detrimental side effects, such as hair loss, fatigue, nausea and increased risk of infection. Occasionally, surgery is also an option.

Professor June at work
Source: Jessica Kourkounis for The New York Times
HIV (Human Immunodeficiency Virus) is a virus that causes AIDS, a condition that leads to failure of the immune system and leaves a person extremely susceptible to opportunistic infections. HIV infects cells within the immune system. One of the more common types of cell infected is helper T cells (also known as CD4+ T cells). Helper T cells, as the name suggests, assist the immune system. They help activity of other immune cells through a series of activities, including the activation of cytotoxic T cells (also known as killer T cells, which kill cancerous and infected cells). HIV, however, kills helper T cells, and so results in the inability of cytotoxic T cells to destroy infected cells. This is obviously problematic, and therefore as levels of helper T cells decline, the risk of contracting an opportunistic infection increases. 

However, the mechanism by which HIV works has therapeutic potential - can we harness HIV's ability to reprogramme one type of the body's own cells to debilitate another type of cells? Can we apply this to instead kill harmful cells?

A treatment being developed by Professor June and his team involves taking the clever mechanisms of HIV and turning them on their head. The type of cancer that this focuses on is leukaemia – a form of cancer caused by white blood cells (specifically B cells) growing out of control. Professor June’s technique involves collecting T cells from a cancer patient, and transforming these in a laboratory with a modified (and harmless) form of the HIV virus. The researchers then add genes with information that tells the T cells to make a new protein (chimeric antigen receptor), which allows the T cells to stick to molecules on cancer cell membranes and kill them. The modified T cells then can be injected back into the patient, where they multiply and can begin to fight the cancer.

Manipulation of T cells
Source: The New York Times
“It’s a procedure where we collect their T-cells and they’re infected with a virus that will genetically change them so that they will now see and react against their leukaemia cells,” says Dr David Porter (MD, of the University of Pennsylvania). “And we actually use the HIV virus to do that,” adds Professor June.

This method is extremely difficult to carry out, let alone see positive results from. Professor June’s team have carried out this prospective treatment multiple times in the lab and on animals, and have begun clinical trials with human patients. The results of these preliminary trials is positive. One study involved three patients receiving the treatment, and as a result, two of these patients went into complete remission - this means the cancer completely went away. A further trial involving ten adult patients and two children showed that nine out of the twelve were successfully treated. One of the children in the second study was Emma Whitehead, then 6 years old. Before the study her cancer had relapsed (come back) twice, and she was running out of options. She was put forward for the study and was chosen to be a patient volunteer. At first the treatment made her extremely unwell, but she emerged cancer free, and is now in complete remission.

These results are extremely encouraging and impressive, but unfortunately for one patient in the first study and three in the second the results were not as hoped. However, this does demonstrate a huge potential for development into this treatment, to hone and refine before it is suitable for distribution to the masses. Currently, there are several similar therapies being tested in both the lab and in clinical trials across the globe, and with the huge amount of funding that cancer research recieves (with recent campaigns such as the #nomakeupselfie) hopefully this treatment will one day be available to all.

A video depicting this idea, which heavily features Emma Whitehead's story, is shown here.

1 comment:

  1. This is really interesting, you are incredibly smart :)