Q.16 Which one of the following drugs is NOT an immune checkpoint inhibitor?
(A) Ipilimumab
(B) Pembrolizumab
(C) Nivolumab
(D) Trastuzumab
Trastuzumab is not an immune checkpoint inhibitor. Ipilimumab, Pembrolizumab, and Nivolumab target immune checkpoints like CTLA-4 or PD-1 to unleash T-cell activity against cancer, while Trastuzumab is a monoclonal antibody specific to HER2 receptors in breast cancer.
Option Analysis
Ipilimumab (A): This drug blocks CTLA-4, a key checkpoint protein on T cells that downregulates immune responses. Approved for melanoma, it enhances T-cell activation against tumors.
Pembrolizumab (B): Targets PD-1 on T cells, preventing its interaction with PD-L1 on cancer cells. Widely used for various cancers including lung and melanoma, it restores antitumor immunity.
Nivolumab (C): Another PD-1 inhibitor, similar to Pembrolizumab, approved for melanoma, lung cancer, and more. It blocks PD-1 signaling to boost T-cell killing of cancer cells.
Trastuzumab (D): Binds to HER2 protein overexpressed in certain breast cancers, inhibiting growth signals. It functions as a targeted therapy, not by modulating immune checkpoints.
Immune checkpoint inhibitors have transformed cancer treatment by blocking proteins like CTLA-4 and PD-1 that cancer cells exploit to evade immunity. In exams testing which one of the following drugs is NOT an immune checkpoint inhibitor, options like Ipilimumab, Pembrolizumab, Nivolumab, and Trastuzumab demand precise differentiation. This immune checkpoint inhibitor guide clarifies mechanisms for competitive exams.
Understanding Immune Checkpoint Inhibitors
These drugs release the “brakes” on T cells. CTLA-4 inhibitors like Ipilimumab act early in T-cell activation, while PD-1 inhibitors (Pembrolizumab, Nivolumab) block late-stage suppression by PD-L1 on tumors.
Detailed Drug Breakdown
| Drug | Target | Mechanism | Cancer Types | Checkpoint Inhibitor? |
|---|---|---|---|---|
| Ipilimumab | CTLA-4 | Blocks T-cell inhibition | Melanoma | Yes |
| Pembrolizumab | PD-1 | Prevents PD-L1 binding | Lung, Melanoma | Yes |
| Nivolumab | PD-1 | Enhances T-cell attack | Melanoma, NSCLC | Yes |
| Trastuzumab | HER2 | Inhibits growth signals | Breast | No |
Why Trastuzumab Stands Out
Unlike immune checkpoint inhibitors, Trastuzumab targets HER2-overexpressing cells directly via antibody-dependent cytotoxicity, without involving CTLA-4 or PD-1 pathways. This makes it the correct answer for “NOT an immune checkpoint inhibitor”.
For IIT JAM aspirants, memorize: Checkpoint drugs boost systemic immunity; Trastuzumab is tumor-specific targeted therapy.
