Antineoplast:

A drug that prevents, kills, or blocks the growth and spread of cancer cells.
Affects immune system and reactivity due to its ability to prevent the development, growth, or proliferation of malignant cells.

Any of several drugs that control or kill neoplastic cells; used in chemotherapy to kill cancer cells; all have unpleasant side effects that may include nausea and vomiting and hair loss and suppression of bone marrow function.