Alkylating agents are : a) Vincristine b) Actinomycin–D c) Chlorambucil d) 5–Fluorouracil e) Cyclophosphamide

## **Core Concept**
Alkylating agents are a type of chemotherapy drug that work by adding an alkyl group to the DNA of cancer cells, interfering with their replication and ultimately leading to cell death. They are commonly used in the treatment of various types of cancer, including leukemias, lymphomas, and solid tumors.

## **Why the Correct Answer is Right**
The correct answer includes options c) Chlorambucil and e) Cyclophosphamide, both of which are indeed alkylating agents. Chlorambucil works by cross-linking DNA strands, thereby inhibiting DNA replication and transcription. Cyclophosphamide, a widely used alkylating agent, requires metabolic activation to form its active form, which then cross-links DNA.

## **Why Each Wrong Option is Incorrect**
- **Option A: Vincristine** - Vincristine is a vinca alkaloid that works by inhibiting microtubule formation in the mitotic spindle, resulting in cell cycle arrest at metaphase. It is not an alkylating agent.
- **Option B: Actinomycin–D** - Actinomycin D, also known as dactinomycin, is an antibiotic that intercalates into DNA and inhibits RNA synthesis. It is not classified as an alkylating agent.
- **Option D: 5–Fluorouracil** - 5-Fluorouracil (5-FU) is an antimetabolite that inhibits thymidylate synthase, disrupting DNA synthesis. It is not an alkylating agent.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that alkylating agents are most effective against rapidly proliferating cells but can also affect slow-growing or resting cells, making them useful in a variety of cancers. However, they can also lead to secondary malignancies due to their mutagenic effects.

## **Correct Answer: C. Chlorambucil, Cyclophosphamide**