Which agent in the induction regimen is a microtubule inhibitor?

Which agent in the induction regimen is a microtubule inhibitor?

• A. Asparaginase
• B. Vincristine
• C. Daunorubicin
• D. Prednisone

Answer: (B)

The essential idea is how microtubule dynamics are targeted by chemotherapy. Vincristine binds tubulin and prevents microtubule polymerization, so the mitotic spindle cannot form properly. This blocks cells in metaphase and drives them to die, which is exactly how microtubule inhibitors work. Vincristine is a vinca alkaloid and is a standard part of many induction regimens for ALL because of this mechanism. Asparaginase works by depleting circulating asparagine, starving leukemia cells that depend on it for protein synthesis. Daunorubicin intercalates into DNA and inhibits topoisomerase II, generating DNA damage. Prednisone is a glucocorticoid that promotes apoptosis in lymphoid cells. None of these disrupt microtubule assembly, so they’re not microtubule inhibitors.

The essential idea is how microtubule dynamics are targeted by chemotherapy. Vincristine binds tubulin and prevents microtubule polymerization, so the mitotic spindle cannot form properly. This blocks cells in metaphase and drives them to die, which is exactly how microtubule inhibitors work. Vincristine is a vinca alkaloid and is a standard part of many induction regimens for ALL because of this mechanism.

Asparaginase works by depleting circulating asparagine, starving leukemia cells that depend on it for protein synthesis. Daunorubicin intercalates into DNA and inhibits topoisomerase II, generating DNA damage. Prednisone is a glucocorticoid that promotes apoptosis in lymphoid cells. None of these disrupt microtubule assembly, so they’re not microtubule inhibitors.