Cell Cycle Specificity

CELL CYCLE SPECIFICITY
Cell cycle was presented by Dr. Holy in Foundations.

Cancer drugs can be divided into two general classes: CELL CYCLE SPECIFIC DRUGS (CCS; esp. plant alkaloids and antimetabolites), and CELL CYCLE NON-SPECIFIC DRUGS (CCNS; esp. alkylating agents and some natural products). Antineoplastic agents can also be organized according to their chemical class, mechanism of action, therapeutic use or their toxicities.

all cells (normal and neoplastic) progress through the cell cycle
cells spend a different percentage of time in each portion of the cell cycle
- the percentages indicated in the figure are typical for a neoplastic cell

in particular, the duration of both G₀ and G₁ can vary dramatically

drugs that act only during a specific portion of the cell cycle (CCS drugs) will be least effective at treating cancers who have low growth fractions (i.e., most of the cells are in G₀)

it is common to follow treatment with a CCNS drug with a CCS drug, so that cancer cells are recruited into the cell cycle, where CCS drugs can be more effective

CELL CYCLE SPECIFIC DRUGS (CCS)	CELL CYCLE NON-SPECIFIC DRUGS (CCNS)
primary action only during specific phase of the cell cycle plant alkaloids: G₂-M DNA synthesis inhibitors: S	any phase, including G₀, although final toxicity may be manifested during a specific phase crosslinking agents anthracycline antibiotics
only proliferating cells killed (high growth factor tumors preferentially eliminated)	both proliferating and non-proliferating cells killed (attack both high and low growth factor tumours)
schedule dependent (duration and timing matter in addition to dose)	dose dependent (total dose matters more than schedule)

2015 Antineoplastics

CELL CYCLE SPECIFICITY Cell cycle was presented by Dr. Holy in Foundations.

CELL CYCLE SPECIFICITY
Cell cycle was presented by Dr. Holy in Foundations.