[jfarlow]

Cancer = you, but misregulated. Code for various tissues are turned on at 'incorrect' times, including code for profliferateNow(), ignoreAutoDestruct(), and can start running contradictory code like beNeuronLike() and beMuscleLike() simultaneously.

T-Cells generally sense 'rogue' cells, and command them to auto-destruct. Many cancers are rendered invisible to your immune system because their presentation to the immune system is indistinguishable from a healthy cell in that it doesn't present any feature that is not found elsewhere in the body.

In an engineered Car-T cell, an immune cell is reprogrammed by providing the cell with a DNA blueprint for a synthetically engineered protein called a 'Chimeric Antigen Receptor (CAR)'[1]. That engineered protein has two major functions - sense a particular cell type, and activate the T-cell to kill whatever triggers its sensor. The sensing mechanism is relatively arbitrary from an engineering perspective, so we engineer the sensor to sense a particular cell type which has become cancerous. And the attack trigger is a shortcut of the entire immunological activation pathway - skipping straight to sense->attack, bypassing the natural defenses to prevent autoimmune problems.

Because the sensing mechanism of the synthetic protein is modular, these engineered proteins can swap out various 'sensors' to create new therapies relatively easily. Sense any cell that looks like a [lymphocyte/B-cell] and [kill it]. More sophistocated versions of these synthetic proteins can actually start to incorporate and-gates and other formal logic into their sensing capabilities:

if(sense(neuron && muscle)){ killTarget(); }

(where no neuron-like markers should ever show up with muscle-like markers except in a genetically scrambled cell, i.e. cancer).

[1] https://serotiny.bio/notes/proteins/car19/