USMLE PRACTICE QUESTION #68
TOPIC: Immunopharmacology.
Today’s question will test your understanding of immune system pharmacology.
I’m Paul Ciurysek, MD, and this is The USMLE Times: An independent, subscriber-supported newsletter designed to help you survive medical school, pass your USMLE exams, and match into your dream residency program. This question and all others are free for 48 hours; after that, it’s available to Premium subscribers only.
A 63-year-old woman with metastatic renal cell carcinoma is being considered for treatment with aldesleukin. Before initiating therapy, her oncologist explains the mechanism of action of aldesleukin. Which of the following best describes the mechanism of action of aldesleukin?
A. Inhibition of mTOR signaling to block cell growth and proliferation
B. Activation of G-protein-coupled receptors to promote apoptosis in cancer cells
C. Recombinant form of interleukin-2 (IL-2) that stimulates the immune system
D. Inhibition of tyrosine kinase activity to block cell signaling pathways
E. Induction of programmed cell death by blocking anti-apoptotic proteins
Detailed Breakdown of Answers + Correct Answer Below ⏬
ANSWER + QUESTION BREAKDOWN
The mental model used to answer this question comes from our detailed test-taking skills masterclass. Here’s how to think through this question:
Step 1. Read the last line to determine the actual question: “Which of the following best describes the mechanism of action of aldesleukin?”
Step 2: Is this a first-, second-, or third-order question?
Answer: 1st order. Everything you need to know to answer this question is found in the last line. Thus, there is no need to read the entire vignette, and there is no need to think beyond the actual question being posed.
Step 3: Ask yourself: “What’s the MOA of aldesleukin?”
Step 4. Look at the answer choices and select the option most closely resembling your thoughts from “Step 3” above.
GENERAL ANALYSIS
The question is about the mechanism of action of aldesleukin, which can be used in treating metastatic renal cell carcinoma. Based on the provided search results, let's analyze each answer choice:
ANSWER CHOICES:
CHOICE A: Inhibition of mTOR signaling to block cell growth and proliferation
Explanation: This mechanism is associated with drugs like everolimus and temsirolimus, which are mTOR inhibitors. Aldesleukin doesn’t work through this mechanism.
CHOICE B: Activation of G-protein-coupled receptors to promote apoptosis in cancer cells
Explanation: Aldesleukin doesn’t work through a G-protein-coupled receptor.
CHOICE C: Recombinant form of interleukin-2 (IL-2) that stimulates the immune system
Explanation: Aldesleukin is a recombinant form of interleukin-2 (IL-2), which stimulates the proliferation and activation of T cells and natural killer (NK) cells, enhancing the immune response against tumors.
CHOICE D: Inhibition of tyrosine kinase activity to block cell signaling pathways
Explanation: This mechanism is associated with tyrosine kinase inhibitors such as imatinib and is not a mechanism used by aldesleukin.
CHOICE E: Induction of programmed cell death by blocking anti-apoptotic proteins
Explanation: This mechanism is related to drugs that induce apoptosis by targeting anti-apoptotic proteins like BCL-2. Aldesleukin does not target these proteins.
FINAL VERDICT…
Aldesleukin is a recombinant form of interleukin-2, a cytokine that plays a critical role in the immune system by promoting the proliferation and activation of T cells and natural killer cells. By enhancing these immune responses, aldesleukin helps the body target and destroy cancer cells, making it effective in treating certain types of cancer, such as metastatic renal cell carcinoma.
CORRECT ANSWER: C) Recombinant form of interleukin-2 (IL-2) that stimulates the immune system
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