Remove the tumor's mask
Cancer cells hide within normal structures like blood vessels. In order to conceal themselves, cancer cells rely on proteins from nearby healthy cells to hide their malignant proteins. New agents such as engineered peptide antibodies are increasingly able to strip away these disguises, exposing the tumors.

Make the tumor less productive
Cancer cells actively pump out factors called immune system suppressors that wave off immune sentries and mislead them into thinking that the tumors are normal, healthy cells. New compounds currently being tested can suppress the suppressors. Cancers are also rich in suppressor T cells that direct the natural killer cells not to attack the cancer cells resulting in immune tolerance. Certain drugs and radiation can wipe out these suppressor T cells and break the immune tolerance.

Stack the immune system's deck
The body's T cells, which target invaders, may not be able to recognize the cancer cells.  However, it is now possible to take from a patient some mononuclear cells and induce them to differentiate into immature dendritic cells (or antigen presenting cells).  When mixed with cancer cells, the dendritic cells will identify the cancer cell proteins and pass the information to cytotoxic T lymphocytes (natural killer T cells), thereby training the infantry T cells to spot the bad guys. The killer T cell population can also be enhanced in the lab and then injected back into the body.

Build the right immune cells
Another way to sensitize T cells to detect cancer cells is to redesign them for the job. Scientist does this by extracting the cells, genetically modifying them to recognize telltale cancer proteins and then using these supercells to treat the patient.

Firstly, the intra-tumoral injection of immature dendritic cells  followed by infusion of cytokine activated memory T cells results in induction of millions of cytotoxic T cells which have been trained to zero in on the cancer cells.

This is followed by radiotherapy a week later which causes DNA damage, protein damage and apoptosis of the cancer cells resulting in debulking of the tumour and release of tumour antigens. Radiotherapy also wipes out the regulatory T cells, thereby helping to break up the cancer's immune tolerance.

A second intra-tumoral injection of immature dendritic cells followed by activated memory T cells infusion allows the immune system to boost the induction of more cytotoxic T lymphocytes which will mop up all remaining cancer cells including those which could have undergone transformation or mutation. This patient specific induced therapeutic cancer vaccine is believed to be effective in killing off microscopic and tiny nests of cancer cells, thereby preventing any future cancer recurrence.

Figures A to C

Computed tomography ( CT ) radiographs showing metastatic cancer sites ( solid arrows ) before and after treatment in two breast cancer and one gastric cancer patient, respectively.

Figure D

PET-CT showing resolution of treated ( circled ) and un-treated metastatic sites ( open arrows ) in a patient with cervical cancer.

Circled sites were injected with immature dendritic cells ( iDC ) followed by intensity modulated radiotherapy ( IMRT ) as per protocol and resolved as were untreated metastatic lesions ( open arrows ).