What is cancer ?
- Cancer is an uncontrolled growth and multiplication of cells in a given organ (for example, the lung or stomach), which are damaged due to inborn (genetic) or external triggers (such as smoking or high doses of radiation).
How do cancer cells differ from normal ones ?
- While normal cells are programmed to multiply and grow to a certain size and stay so, cancer cells, whose DNA is mutated due to such damage, go on a rampant growth leading to tumours, weakening the body and ultimately even death.
Cancer treatment until now :
- Surgical removal of the tumour has been one option, but it does not guarantee total removal (even a few leftover cells might grow again), nor its recurrence if the original cause is not addressed.
- Radiation therapy using high power gamma rays has also been tried, again with limited success.
- Combining drugs along with shining the tumour using radiation such as gammarays for short periods of time has also been tried. But the trouble is that they need to be used for sustained periods.
Immunological approach to treat cancer :
- This uses the inbuilt defense mechanism in the body. The white blood cells play a main role here.
- The B-Cells therein recognize the shape of the surface protrusion (call it the biometric ID) on the invading cell (be it a microbe or a cancer cell), synthesises proteins called immunoglobulins which fit into the surface of the invading cells and remove them.
- Importantly, this shape of the intruder’s surface is “remembered” so that when a fresh attack by the same invader occurs, B cells are prepared. This too is the basis of childhood vaccines.
- The surface geographic “tag” is termed the antigen and the proteins made by B-cells are called antibodies.
- Cancer cells also have biometric IDs, and these are termed neoantigens. Anticancer vaccines are based on the principle of antibodies made against such neoantigens.
- A recent approach in the field is to for the oncologist to isolate a piece of cancer tissue from the patient, and collaborate with a group of molecular bioanalysts to identify the neoantigen on the cancer cells.
- Next, the oncologist asks an immunologist collaborator to prepare the specific antibody molecule, which can be injected to the patient so as to stop recurrence of the tumour.
- This is thus a therapeutic vaccine (not a preventive vaccine such as the one against hepatitis or mumps).
- Some such cancer vaccines are already in the market, for example, HER2 against breast cancer, Revenge against cancer and TVEC against melanoma.
The latest developments in cancer treatment : Nobelists 2018
- This year’s Nobelists have taken a different approach to treat cancer.
- They concentrated not on the B-lymphocytes but their partners, the T cells.
- T cells release chemicals that push the invading cells to commit suicide (what is called apoptosis).
- Each T cell has clawlike receptors on its surface that locks into antigens foreign or abnormal. But the T cell needs to be activated by certain proteins (called Tcell accelerators) before it triggers such a response.
- Additionally, there are also other proteins that help check the T cell from going on a rampage. These proteins are called ‘brakes’ or “check point proteins”.
Nobel Prize in Medicine 2018 : James Allison and Tasuku Honjo
- Dr James Allison of the MD Anderson Cancer Centre at the University of Texas, Houston, TX, USA, has been working since the early 1990s on one such “brake” or “checkpoint “protein called CTLA4, which downregulates the immune response of Tcells.
- He wondered whether one could find a mechanism (or a protein) which can release this brake on CTLA4. By 199495, his group produced a molecule called “antiCTLA4”, which, when injected on mice with cancer, unlocked the antitumour activity and cured the mouse of cancer.
- Promising results from emerged, and in 2010, an important clinical study showed striking effects in patients with advanced melanomas, a type of skin cancer. In several patients, signs of remaining cancer disappeared. Such remarkable results have never been seen before in this patient group”.
- Tasuku Honjo, currently at Kyoto University, Japan discovered, even before Allison, in 1992, that a protein called PD1 is expressed on the surface of T cells.
- His continuing work on it showed that it too is a checkpoint protein; if it were released, T cells can exhibit antitumour activity.
- Towards this, he developed the antibody AntiPD1, which when introduced for the treatment of patients with different types of cancer, the results were dramatic.
- The trick in both instances, Allison’s or Honjo’s, is to find molecules that will release the brake or the checkpoint, and let the anticancer activity occur.
- With the advances made by the Allison’s and Honjo’s groups, it does appear that the cancer's reign may indeed come to an end sooner than later.