Phalanxifor

''"The drug was Phalanxifor, this molecule designed to attach itself to cancer cells and slow their growth." - ''Hazel Grace

''"There is no such thing as Phalanxifor. I made it up because I would like for it to exist." - ''John Green

Phalanxifor, as mentioned in the book, is a drug as a short term remedy of cancer that slows the growth of cancer, but does not eradicate what is already there. It is an infamous drug for not working, in about 70% of people.

As mentioned at the end of the book, John Green states it is not a real drug.

Appearances
In The Fault in Our Stars, the drug phalanxifor was taken by Hazel Grace to sustain her fairly normal level of cancer for a substantial period of time instead of letting it grow to higher and more dangerous stages.