Chemotherapy Biotherapy Certification ONS Practice Testq

At which cell cycle phases do alkylating agents demonstrate maximal activity?

1. G0 and G1 phases

2. G2-M phase and near the G1-S phase

3. S and G1 phases

4. Only during mitosis

The correct answer is: G2-M phase and near the G1-S phase

Alkylating agents demonstrate maximal activity primarily during the G2-M phase and near the G1-S phase of the cell cycle. These agents work by forming covalent bonds with DNA, leading to cross-linking and disruption of the DNA structure, which ultimately interferes with the cell's ability to divide and propagate. The G2-M phase is critical for the normal preparation and execution of mitosis, where DNA damage can result in cell cycle arrest and apoptosis. Additionally, as the cell transitions from G1 to S phase, the DNA is being prepared for replication. Alkylating agents can effectively target cells at these junctures, significantly impacting their viability and reproductive capacity. The activity of alkylating agents is not as pronounced in the G0 phase, where cells are in a quiescent state and not actively dividing, nor is it limited to the mitotic phase alone. Understanding the timing of the cell cycle phases where these agents are most effective can aid in optimizing treatment regimens for various malignancies.